Recanalization and flow regulate venous thrombus resolution and matrix metalloproteinase expression in vivo.

PubMed

Chabasse, Christine; Siefert, Suzanne A; Chaudry, Mohammed; Hoofnagle, Mark H; Lal, Brajesh K; Sarkar, Rajabrata

2015-01-01

We examined the role of thrombus recanalization and ongoing blood flow in the process of thrombus resolution by comparing two murine in vivo models of deep venous thrombosis. In CD1 mice, we performed surgical inferior vena cava ligation (stasis thrombosis), stenosis (thrombosis with recanalization), or sham procedure. We analyzed thrombus weight over time as a measure of thrombus resolution and quantified the messenger RNA and protein levels of membrane-type matrix metalloproteinases (MT-MMPs) as well as effectors of the plasmin complex at days 4, 8, and 12 after surgery. Despite similar initial thrombus size, the presence of ongoing blood flow (stenosis model) was associated with a 45.91% subsequent improvement in thrombus resolution at day 8 and 12.57% at day 12 compared with stasis thrombosis (ligation model). Immunoblot and real-time polymerase chain reaction analysis demonstrated a difference in MMP-2 and MMP-9 activity at day 8 between the two models (P = .03 and P = .006, respectively) as well as a difference in MT2-MMP gene expression at day 8 (P = .044) and day 12 (P = .03) and MT1-MMP protein expression at day 4 (P = .021). Histologic analyses revealed distinct areas of recanalization in the thrombi of the stenosis model compared with the ligation model as well as the recruitment of inflammatory cells, especially macrophages, and a focal pattern of localized expression of MT1-MMP and MT3-MMP proteins surrounding the areas of recanalization in the stenosis model. Recanalization and ongoing blood flow accelerate deep venous thrombus resolution in vivo and are associated with distinct patterns of MT1-MMP and MT3-MMP expression and macrophage localization in areas of intrathrombus recanalization. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Effect of Vacuum on Venous Drainage: an Experimental Evaluation on Pediatric Venous Cannulas and Tubing Systems.

PubMed

Vida, V L; Bhattarai, A; Speggiorin, S; Zanella, F; Stellin, G

2014-01-01

To observe how vacuum assisted venous drainage (VAVD) may influence the flow in a cardiopulmonary bypass circuit with different size of venous lines and cannulas. The experimental circuit was assembled to represent the cardiopulmonary bypass circuit routinely used during cardiac surgery. Wall suction was applied directly, modulated and measured into the venous reservoir. The blood flow was measured with a flow-meter positioned on the venous line. The circuit prime volume was replaced with group O date expired re-suspended red cells and Plasmalyte 148 to a hematocrit of 28% to 30%. In an open circuit with gravity siphon venous drain, angled cannulae drain more than straight ones regardless the amount of suction applied to the venous line (16 Fr straight cannula (S) drains 90 ml/min less than a 16 Fr angled (A) with a siphon gravity). The same flow can be obtained with lower cannula size and higher suction (i.e. 12 A with and -30 mmHg). Tables have been created to list how the flow varies according to the size of the cannulas, the size of the venous tubes, and the amount of suction applied to the system. Vacuum assisted venous drainage allows the use of smaller cannulae and venous lines to maintain a good venous return, which is very useful during minimally invasive approaches. The present study should be considered as a preliminary attempt to create a scientific-based starting point for a uniform the use of VAVD.

Manual lymphatic drainage in chronic venous disease: a duplex ultrasound study.

PubMed

Dos Santos Crisóstomo, Rute Sofia; Candeias, Miguel Sandu; Ribeiro, Ana Margarida Martins; da Luz Belo Martins, Catarina; Armada-da-Silva, Paulo As

2014-12-01

To compare the effect of call-up and reabsorption maneuvers of manual lymphatic drainage on blood flow in femoral vein and great saphenous vein in patients with chronic venous disease and healthy controls. Forty-one subjects participated in this study (mean age: 42.68(15.23)), 23 with chronic venous disease (chronic venous disease group) with clinical classification C1-5 of clinical-etiological-anatomical-pathological (CEAP) and 18 healthy subjects (control group). Call-up and reabsorption maneuvers were randomly applied in the medial aspect of the thigh. The cross-sectional areas, as well as the peak and the mean blood flow velocity at femoral vein and great saphenous vein, were assessed by Duplex ultrasound at the baseline and during maneuvers. The venous flow volume changes were calculated. The venous flow volume in femoral vein and great saphenous vein increased during both manual lymphatic drainage maneuvers and in both groups (P < 0.05). The two maneuvers had a similar effect on femoral vein and great saphenous vein hemodynamics, and in both the chronic venous disease and control groups. As a result of the call-up maneuver, the flow volume augmentations, as a result of call-up maneuver, decreased with the severity of chronic venous disease in those patients measured by the clinical classification of CEAP (r = -0.64; P = 0.03). Manual lymphatic drainage increases the venous blood flow in the lower extremity with a magnitude that is independent from the specific maneuver employed or the presence of chronic venous disease. Therefore, manual lymphatic drainage may be an alternative strategy for the treatment and prevention of venous stasis complications in chronic venous disease. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Measurement of Venous Blood Flow in the Lower Limbs: Prevention of Deep Vein Thrombosis during Prolonged Sitting

DTIC Science & Technology

2004-06-01

Abstract. The venous blood flow during stretching and deep breathing in the sitting posture was examined in the present study. First, an...increase in the venous return. Therefore, we suggest that stretching and deep breathing can be used sometimes as preventive measures for deep vein...thrombosis during prolonged sitting. Keywords. Venous blood flow, Near infrared spectroscopy, Deep vein thrombosis. 1. Introduction It has been

Ultrasound SIV measurement of helical valvular flow behind the great saphenous vein

NASA Astrophysics Data System (ADS)

Park, Jun Hong; Kim, Jeong Ju; Lee, Sang Joon; Yeom, Eunseop; Experimental Fluid Mechanics Laboratory Team; LaboratoryMicrothermal; Microfluidic Measurements Collaboration

2017-11-01

Dysfunction of venous valve and induced secondary abnormal flow are closely associated with venous diseases. Thus, detailed analysis of venous valvular flow is invaluable from biological and medical perspectives. However, most previous studies on venous perivalvular flows were based on qualitative analyses. On the contrary, quantitative analysis on the perivalvular flows has not been fully understood yet. In this study, 3D valvular flows under in vitro and in vivo conditions were experimentally investigated using ultrasound speckle image velocimetry (SIV) for analyzing their flow characteristics. The results for in vitro model obtained by the SIV technique were compared with those derived by numerical simulation and color Doppler method to validate its measurement accuracy. Then blood flow in the human great saphenous vein was measured using the SIV with respect to the dimensionless index, helical intensity. The results obtained by the SIV method are well matched well with those obtained by the numerical simulation and color Doppler method. The hemodynamic characteristics of 3D valvular flows measured by the validated SIV method would be helpful in diagnosis of valve-related venous diseases. None.

Temperature and blood flow distribution in the human leg during passive heat stress.

PubMed

Chiesa, Scott T; Trangmar, Steven J; González-Alonso, José

2016-05-01

The influence of temperature on the hemodynamic adjustments to direct passive heat stress within the leg's major arterial and venous vessels and compartments remains unclear. Fifteen healthy young males were tested during exposure to either passive whole body heat stress to levels approaching thermal tolerance [core temperature (Tc) + 2°C; study 1; n = 8] or single leg heat stress (Tc + 0°C; study 2; n = 7). Whole body heat stress increased perfusion and decreased oscillatory shear index in relation to the rise in leg temperature (Tleg) in all three major arteries supplying the leg, plateauing in the common and superficial femoral arteries before reaching severe heat stress levels. Isolated leg heat stress increased arterial blood flows and shear patterns to a level similar to that obtained during moderate core hyperthermia (Tc + 1°C). Despite modest increases in great saphenous venous (GSV) blood flow (0.2 l/min), the deep venous system accounted for the majority of returning flow (common femoral vein 0.7 l/min) during intense to severe levels of heat stress. Rapid cooling of a single leg during severe whole body heat stress resulted in an equivalent blood flow reduction in the major artery supplying the thigh deep tissues only, suggesting central temperature-sensitive mechanisms contribute to skin blood flow alone. These findings further our knowledge of leg hemodynamic responses during direct heat stress and provide evidence of potentially beneficial vascular alterations during isolated limb heat stress that are equivalent to those experienced during exposure to moderate levels of whole body hyperthermia. Copyright © 2016 the American Physiological Society.

Temperature and blood flow distribution in the human leg during passive heat stress

PubMed Central

Chiesa, Scott T.; Trangmar, Steven J.

2016-01-01

The influence of temperature on the hemodynamic adjustments to direct passive heat stress within the leg's major arterial and venous vessels and compartments remains unclear. Fifteen healthy young males were tested during exposure to either passive whole body heat stress to levels approaching thermal tolerance [core temperature (Tc) + 2°C; study 1; n = 8] or single leg heat stress (Tc + 0°C; study 2; n = 7). Whole body heat stress increased perfusion and decreased oscillatory shear index in relation to the rise in leg temperature (Tleg) in all three major arteries supplying the leg, plateauing in the common and superficial femoral arteries before reaching severe heat stress levels. Isolated leg heat stress increased arterial blood flows and shear patterns to a level similar to that obtained during moderate core hyperthermia (Tc + 1°C). Despite modest increases in great saphenous venous (GSV) blood flow (0.2 l/min), the deep venous system accounted for the majority of returning flow (common femoral vein 0.7 l/min) during intense to severe levels of heat stress. Rapid cooling of a single leg during severe whole body heat stress resulted in an equivalent blood flow reduction in the major artery supplying the thigh deep tissues only, suggesting central temperature-sensitive mechanisms contribute to skin blood flow alone. These findings further our knowledge of leg hemodynamic responses during direct heat stress and provide evidence of potentially beneficial vascular alterations during isolated limb heat stress that are equivalent to those experienced during exposure to moderate levels of whole body hyperthermia. PMID:26823344

A postscript to Circulation of the blood: men and ideas.

PubMed

Riley, R L

1982-10-01

Since 1964, when Fishman and Richards published Circulation of the Blood: Men and Ideas, Guyton's model of the circulation, in which mean circulatory pressure serves as the upstream pressure for venous return, has been extended, and the concept of vascular smooth muscle tone acting like the pressure surrounding a Starling resistor has been postulated. According to this scheme, the positive zero flow intercepts of rapidly determined arterial pressure-flow curves are the effective downstream pressures for arterial flow to different tissues. The arterioles, like Starling resistors, determine the downstream pressures and are followed by abrupt pressure drops, or "waterfalls." Capillary pressures are closely linked to those of the venules into which they flow. Capillary-venular pressures are the upstream pressures for venous return. In exercising muscles, reduced arteriolar tone lowers arteriolar pressure and increases arterial flow. This, in turn, raises capillary-venular pressure and increases venous flow. The arteriolar-capillary waterfall is decreased or eliminated. Total blood flow is increased by diversion of blood from tissues with slow venous drainage to muscles with fast venous drainage (low resistance X compliance). The heart pumps away the increased venous return by shifting to a new ventricular function curve.

To what extent might deep venous thrombosis and chronic venous insufficiency share a common etiology?

PubMed

Malone, P Colm; Agutter, P S

2009-08-01

According to the valve cusp hypoxia hypothesis (VCHH), deep venous thrombosis is caused by sustained non-pulsatile (streamline) venous blood flow. This leads to hypoxemia in the valve pockets; hypoxic injury to the inner (parietalis) endothelium of the cusp leaflets activates the elk-1/egr-1 pathway, leading to leukocyte and platelet swarming at the site of injury and, potentially, blood coagulation. Here, we propose an extension of the VCHH to account for chronic venous insufficiency. First, should the foregoing events not proceed to frank thrombogenesis, the valves may nevertheless be chronically injured and become incompetent. Serial incompetence in lower limb valves may then generate ''passive'' venous hypertension. Second, should ostial valve thrombosis obstruct venous return from muscles via tributaries draining into the femoral vein, as Virchow illustrated, ''active'' venous hypertension may supervene: muscle contraction would force the blood in the vessels behind the blocked ostial valves to re-route. Passive or active venous hypertension opposes return flow, leading to luminal hypoxemia and vein wall distension, which in turn may impair vasa venarum perfusion; the resulting mural endothelial hypoxia would lead to leukocyte invasion of the wall and remodelling of the media. We propose that varicose veins result if gross active hypertension stretches the valve ''rings'', rendering attached valves incompetent caudad to obstructed sites, replacing normal centripetal flow in perforating veins with centrifugal flow and over-distending those vessels. We also discuss how hypoxemia-related venous/capillary wall lesions may lead to accumulation of leukocytes, progressive blockage of capillary blood flow, lipodermosclerosis and skin ulceration.

Personal Computer System for Automatic Coronary Venous Flow Measurement

PubMed Central

Dew, Robert B.

1985-01-01

We developed an automated system based on an IBM PC/XT Personal computer to measure coronary venous blood flow during cardiac catheterization. Flow is determined by a thermodilution technique in which a cold saline solution is infused through a catheter into the coronary venous system. Regional temperature fluctuations sensed by the catheter are used to determine great cardiac vein and coronary sinus blood flow. The computer system replaces manual methods of acquiring and analyzing temperature data related to flow measurement, thereby increasing the speed and accuracy with which repetitive flow determinations can be made.

Duration and Adverse Events of Non-cuffed Catheter in Patients With Hemodialysis

ClinicalTrials.gov

2014-10-09

Renal Failure Chronic Requiring Hemodialysis; Central Venous Catheterization; Inadequate Hemodialysis Blood Flow; Venous Stenosis; Venous Thrombosis; Infection Due to Central Venous Catheter; Central Venous Catheter Thrombosis

In Vitro MRV-based Hemodynamic Study of Complex Helical Flow in a Patient-specific Jugular Model

NASA Astrophysics Data System (ADS)

Kefayati, Sarah; Acevedo-Bolton, Gabriel; Haraldsson, Henrik; Saloner, David

2014-11-01

Neurointerventional Radiologists are frequently requested to evaluate the venous side of the intracranial circulation for a variety of conditions including: Chronic Cerebrospinal Venous Insufficiency thought to play a role in the development of multiple sclerosis; sigmoid sinus diverticulum which has been linked to the presence of pulsatile tinnitus; and jugular vein distension which is related to cardiac dysfunction. Most approaches to evaluating these conditions rely on structural assessment or two dimensional flow analyses. This study was designed to investigate the highly complex jugular flow conditions using magnetic resonance velocimetry (MRV). A jugular phantom was fabricated based on the geometry of the dominant jugular in a tinnitus patient. Volumetric three-component time-resolved velocity fields were obtained using 4D PC-MRI -with the protocol enabling turbulence acquisition- and the patient-specific pulsatile waveform. Flow was highly complex exhibiting regions of jet, high swirling strength, and strong helical pattern with the core originating from the focal point of the jugular bulb. Specifically, flow was analyzed for helicity and the level of turbulence kinetic energy elevated in the core of helix and distally, in the post-narrowing region.

Segmental Blood Flow and Hemodynamic State of Lymphedematous and Nonlymphedematous Arms

PubMed Central

Montgomery, Leslie D.; Dietrich, Mary S.; Armer, Jane M.; Stewart, B. R.

2011-01-01

Abstract Background Findings regarding the influence hemodynamic factors, such as increased arterial blood flow or venous abnormalities, on breast cancer treatment-related lymphedema are mixed. The purpose of this study was to compare segmental arterial blood flow, venous blood return, and blood volumes between breast cancer survivors with treatment-related lymphedema and healthy normal individuals without lymphedema. Methods and Results A Tetrapolar High Resolution Impedance Monitor and Cardiotachometer were used to compare segmental arterial blood flow, venous blood return, and blood volumes between breast cancer survivors with treatment-related lymphedema and healthy normal volunteers. Average arterial blood flow in lymphedema-affected arms was higher than that in arms of healthy normal volunteers or in contralateral nonlymphedema affected arms. Time of venous outflow period of blood flow pulse was lower in lymphedema-affected arms than in healthy normal or lymphedema nonaffected arms. Amplitude of the venous component of blood flow pulse signal was lower in lymphedema-affected arms than in healthy or lymphedema nonaffected arms. Index of venular tone was also lower in lymphedema-affected arms than healthy or lymphedema nonaffected arms. Conclusions Both arterial and venous components may be altered in the lymphedema-affected arms when compared to healthy normal arms and contralateral arms in the breast cancer survivors. PMID:21417765

Mock Circulatory System of the Fontan Circulation to Study Respiration Effects on Venous Flow Behavior

PubMed Central

Vukicevic, M.; Chiulli, J.A.; Conover, T.; Pennati, G.; Hsia, T.Y.; Figliola, R.S.

2013-01-01

We describe an in vitro model of the Fontan circulation with respiration to study subdiaphragmatic venous flow behavior. The venous and arterial connections of a total cavopulmonary connection (TCPC) test section were coupled with a physical lumped parameter (LP) model of the circulation. Intrathoracic and subdiaphragmatic pressure changes associated with normal breathing were applied. This system was tuned for two patients (5 years, 0.67 m2; 10 years, 1.2 m2) to physiological values. System function was verified by comparison to the analytical model on which it was based and by consistency with published clinical measurements. Overall, subdiaphragmatic venous flow was influenced by respiration. Flow within the arteries and veins increased during inspiration but decreased during expiration with retrograde flow in the inferior venous territories. System pressures and flows showed close agreement with the analytical LP model (p < 0.05). The ratio of the flow rates occurring during inspiration to expiration were within the clinical range of values reported elsewhere. The approach used to setup and control the model was effective and provided reasonable comparisons with clinical data. PMID:23644612

Computed tomographic characteristics of collateral venous pathways in dogs with caudal vena cava obstruction.

PubMed

Specchi, Swan; d'Anjou, Marc-André; Carmel, Eric Norman; Bertolini, Giovanna

2014-01-01

Collateral venous pathways develop in dogs with obstruction or increased blood flow resistance at any level of the caudal vena cava in order to maintain venous drainage to the right atrium. The purpose of this retrospective study was to describe the sites, causes of obstruction, and configurations of venous collateral pathways for a group of dogs with caudal vena cava obstruction. Computed tomography databases from two veterinary hospitals were searched for dogs with a diagnosis of caudal vena cava obstruction and multidetector row computed tomographic angiographic (CTA) scans that included the entire caudal vena cava. Images for each included dog were retrieved and collateral venous pathways were characterized using image postprocessing and a classification system previously reported for humans. A total of nine dogs met inclusion criteria and four major collateral venous pathways were identified: deep (n = 2), portal (n = 2), intermediate (n = 7), and superficial (n = 5). More than one collateral venous pathway was present in 5 dogs. An alternative pathway consisting of renal subcapsular collateral veins, arising mainly from the caudal pole of both kidneys, was found in three dogs. In conclusion, findings indicated that collateral venous pathway patterns similar to those described in humans are also present in dogs with caudal vena cava obstruction. These collateral pathways need to be distinguished from other vascular anomalies in dogs. Postprocessing of multidetector-row CTA images allowed delineation of the course of these complicated venous pathways and may be a helpful adjunct for treatment planning in future cases. © 2014 American College of Veterinary Radiology.

Gravitational effects on global hemodynamics in different postures: A closed-loop multiscale mathematical analysis

NASA Astrophysics Data System (ADS)

Zhang, Xiancheng; Noda, Shigeho; Himeno, Ryutaro; Liu, Hao

2017-06-01

We present a novel methodology and strategy to predict pressures and flow rates in the global cardiovascular network in different postures varying from supine to upright. A closed-loop, multiscale mathematical model of the entire cardiovascular system (CVS) is developed through an integration of one-dimensional (1D) modeling of the large systemic arteries and veins, and zero-dimensional (0D) lumped-parameter modeling of the heart, the cardiac-pulmonary circulation, the cardiac and venous valves, as well as the microcirculation. A versatile junction model is proposed and incorporated into the 1D model to cope with splitting and/or merging flows across a multibranched junction, which is validated to be capable of estimating both subcritical and supercritical flows while ensuring the mass conservation and total pressure continuity. To model gravitational effects on global hemodynamics during postural change, a robust venous valve model is further established for the 1D venous flows and distributed throughout the entire venous network with consideration of its anatomically realistic numbers and locations. The present integrated model is proven to enable reasonable prediction of pressure and flow rate waveforms associated with cardiopulmonary circulation, systemic circulation in arteries and veins, as well as microcirculation within normal physiological ranges, particularly in mean venous pressures, which well match the in vivo measurements. Applications of the cardiovascular model at different postures demonstrate that gravity exerts remarkable influence on arterial and venous pressures, venous returns and cardiac outputs whereas venous pressures below the heart level show a specific correlation between central venous and hydrostatic pressures in right atrium and veins.

Blood flow velocity in the popliteal vein using transverse oscillation ultrasound

NASA Astrophysics Data System (ADS)

Bechsgaard, Thor; Hansen, Kristoffer Lindskov; Brandt, Andreas Hjelm; Holbek, Simon; Lönn, Lars; Strandberg, Charlotte; Bækgaard, Niels; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

2016-04-01

Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease. Transverse Oscillation US (TOUS), a non-invasive angle independent method, has been implemented on a commercial scanner. TOUS's advantage compared to SDUS is a more elaborate visualization of complex flow. The aim of this study was to evaluate, whether TOUS perform equal to SDUS for recording velocities in the veins of the lower limbs. Four volunteers were recruited for the study. A standardized flow was provoked with a cuff compression-decompression system placed around the lower leg. The average peak velocity in the popliteal vein of the four volunteers was 151.5 cm/s for SDUS and 105.9 cm/s for TOUS (p <0.001). The average of the peak velocity standard deviations (SD) were 17.0 cm/s for SDUS and 13.1 cm/s for TOUS (p <0.005). The study indicates that TOUS estimates lower peak velocity with improved SD when compared to SDUS. TOUS may be a tool for evaluation of venous disease providing quantitative measures for the evaluation of venous blood flow.

Venous flow during manual lymphatic drainage applied to different regions of the lower extremity in people with and without chronic venous insufficiency: a cross-sectional study.

PubMed

Crisóstomo, R S S; Candeias, M S; Armada-da-Silva, P A S

2017-03-01

To evaluate the effect of manual lymphatic drainage (MLD) on venous flow when applied to the medial and lateral aspects of the thigh and leg in patients with chronic venous insufficiency (CVI) and healthy subjects. Cross-sectional study. Participants were assessed in a school-based health community attendant service. Fifty-seven subjects participated in this study {mean age: 43 [standard deviation (SD) 14] years, 38 women and 19 men}. Of these, 28 subjects had CVI [mean age 47 (SD 12) years] and 29 subjects did not have CVI [mean age 39 (14) years]. MLD was applied by a certificated physical therapist to the medial and lateral aspects of the thigh and leg. Cross-sectional area; blood flow velocities in the femoral vein, great saphenous vein, popliteal vein and small saphenous vein at baseline and during MLD, measured by duplex ultrasound. Flow volume in the femoral vein increased from baseline [5.19 (SD 3.25)cm 3 /second] when MLD was applied to the medial [7.03 (SD 3.65)cm 3 /second; P≤0.001; mean difference -1.69; 95% confidence interval (CI) -2.42 to -0.97] and lateral [6.16 (SD 3.35)cm 3 /second; P≤0.001; mean difference -1.04; 95% CI -1.70 to -0.39] aspects of the thigh. Venous flow augmentation in the femoral vein and great saphenous vein was higher when MLD was applied to the medial aspect of the thigh (P<0.001), while MLD had a similar effect on venous blood flow regardless of whether it was applied to the medial or the lateral aspect of the leg (P=0.731). MLD increases blood flow in deep and superficial veins. MLD should be applied along the route of the venous vessels for improved venous return. Copyright © 2016 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Computational Study of Thrombus Formation and Clotting Factor Effects under Venous Flow Conditions

DTIC Science & Technology

2016-04-26

Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Fort Detrick, MarylandABSTRACT A comprehensive... experimental study. The model allowed us to identify the distinct patterns character- izing the spatial distributions of thrombin, platelets, and fibrin...time, elevated fibrinogen levels may contribute to the development of thrombosis (4,6,12). Quantitative knowledge about the interactions between fibrin

A Case of Left Renal Vein Ligation in a Patient with Solitary Left Kidney Undergoing Liver Transplantation to Control Splenorenal Shunt and Improve Portal Venous Flow.

PubMed

Martino, Rodrigo B; Júnior, Eserval Rocha; Manuel, Valdano; Rocha-Santos, Vinicius; D'Albuquerque, Luis Augusto C; Andraus, Wellington

2017-10-11

BACKGROUND Adequate portal venous flow is required for successful liver transplantation. Reduced venous flow and blood flow 'steal' by collateral vessels are a concern, and when there is a prominent splenorenal shunt present, ligation of the left renal vein has been recommended to improve portal venous blood flow. CASE REPORT A 51-year-old man who had undergone right nephrectomy in childhood required liver transplantation for liver cirrhosis and hepatocellular carcinoma due to hepatitis C virus (HCV) infection. The patient had no other comorbidity and no history of hepatorenal syndrome. At transplantation surgery, portal venous flow was poor and did not improve with ligation of shunt veins, but ligation of the left renal vein improved portal venous flow. On the first and fifth postoperative days, the patient was treated with basiliximab, a chimeric monoclonal antibody to the IL-2 receptor, and methylprednisolone. The calcineurin inhibitor, tacrolimus, was introduced on the fifth postoperative day. On the sixteenth postoperative day, renal color Doppler ultrasound showed normal left renal parenchyma; hepatic Doppler ultrasound showed good portal vein flow and preserved hepatic parenchyma in the liver transplant. CONCLUSIONS This case report has shown that in a patient with a single left kidney, left renal vein ligation is feasible and safe in a patient with no other risk factors for renal impairment following liver transplantation. Modification of postoperative immunosuppression to avoid calcineurin inhibitors in the very early postoperative phase may be important in promoting good recovery of renal function and to avoid the need for postoperative renal dialysis.

Dural arteriovenous fistulas as a cause of intracranial hypertension due to impairment of cranial venous outflow

PubMed Central

Cognard, C.; Casasco, A.; Toevi, M.; Houdart, E.; Chiras, J.; Merland, J.

1998-01-01

OBJECTIVES—A retrospective study was carried out on 13 patients with intracranial dural arteriovenous fistulas (DAVFs) who presented with isolated or associated signs of intracranial hypertension.
METHODS—Nine patients presented with symptoms of intracranial hypertension at the time of diagnosis. Ocular fundoscopy available in 12 patients showed bilateral papilloedema in eight and optic disk atrophy in four. Clinical evolution was particularly noticeable in five patients because of chronic (two patients) or acute (after lumbar shunting or puncture: three patients, one death) tonsillar herniation.
RESULTS—Two patients had a type I fistula (drainage into a sinus, with a normal antegrade flow direction). The remaining 11 had type II fistulas (drainage into a sinus, with abnormal retrograde venous drainage into sinuses or cortical veins). Stenosis or thrombosis of the sinus(es) distal to the fistula was present in five patients. The cerebral venous drainage was abnormal in all patients.
CONCLUSION—Type II (and some type I) DAVFs may present as isolated intracranial hypertension mimicking benign intracranial hypertension. Normal cerebral angiography should be added as a fifth criterion of benign intracranial hypertension. The cerebral venous drainage pattern must be carefully studied by contralateral carotid and vertebral artery injections to correctly evaluate the impairment of the cerebral venous outflow. Lumbar CSF diversion (puncture or shunting) may induce acute tonsillar herniation and should be avoided absolutely. DAVF may induce intracranial hypertension, which has a poor long term prognosis and may lead to an important loss of visual acuity and chronic tonsillar herniation. Consequently, patients with intracranial hypertension must be treated, even agressively, to obliterate the fistula or at least to reduce the arterial flow and to restore a normal cerebral venous drainage. The endovascular treatment may associate arterial or transvenous embolisation and /or surgery. Patients in whom the fistula is not obliterated after an endovascular therapeutic procedure, need continous clinical and angiographical follow up.

 PMID:9728941

MDCT Venography Evaluation of a Rare Collateral Vein Draining from the Left Subclavian Vein to the Great Cardiac Vein

PubMed Central

Abchee, Antoine; Saade, Charbel; Al-Mohiy, Hussain; El-Merhi, Fadi

2014-01-01

Congenital vascular anomalies of the venous drainage in the chest affect both cardiac and non-cardiac structures. Collateral venous drainage from the left subclavian vein to the great cardiac vein is a rare venous drainage pattern. These anomalies present a diagnostic challenge. Multi-detector computed tomography (MDCT) is useful in the diagnosis and treatment planning of these clinically complex disorders. We present a case report of an 18-year-old Caucasian male who came to our institute for evaluation of venous drainage patterns to the heart. We describe the contrast technique of bilateral dual injection MDCT venography and the imaging features of the venous drainage patterns to the heart. PMID:25379351

MDCT Venography Evaluation of a Rare Collateral Vein Draining from the Left Subclavian Vein to the Great Cardiac Vein.

PubMed

Abchee, Antoine; Saade, Charbel; Al-Mohiy, Hussain; El-Merhi, Fadi

2014-01-01

Congenital vascular anomalies of the venous drainage in the chest affect both cardiac and non-cardiac structures. Collateral venous drainage from the left subclavian vein to the great cardiac vein is a rare venous drainage pattern. These anomalies present a diagnostic challenge. Multi-detector computed tomography (MDCT) is useful in the diagnosis and treatment planning of these clinically complex disorders. We present a case report of an 18-year-old Caucasian male who came to our institute for evaluation of venous drainage patterns to the heart. We describe the contrast technique of bilateral dual injection MDCT venography and the imaging features of the venous drainage patterns to the heart.

Vasopressin-induced changes in splanchnic blood flow and hepatic and portal venous pressures in liver resection.

PubMed

Bown, L Sand; Ricksten, S-E; Houltz, E; Einarsson, H; Söndergaard, S; Rizell, M; Lundin, S

2016-05-01

To minimize blood loss during hepatic surgery, various methods are used to reduce pressure and flow within the hepato-splanchnic circulation. In this study, the effect of low- to moderate doses of vasopressin, a potent splanchnic vasoconstrictor, on changes in portal and hepatic venous pressures and splanchnic and hepato-splanchnic blood flows were assessed in elective liver resection surgery. Twelve patients were studied. Cardiac output (CO), stroke volume (SV), mean arterial (MAP), central venous (CVP), portal venous (PVP) and hepatic venous pressures (HVP) were measured, intraoperatively, at baseline and during vasopressin infusion at two infusion rates (2.4 and 4.8 U/h). From arterial and venous blood gases, the portal (splanchnic) and hepato-splanchnic blood flow changes were calculated, using Fick's equation. CO, SV, MAP and CVP increased slightly, but significantly, while systemic vascular resistance and heart rate remained unchanged at the highest infusion rate of vasopressin. PVP was not affected by vasopressin, while HVP increased slightly. Vasopressin infusion at 2.4 and 4.8 U/h reduced portal blood flow (-26% and -37%, respectively) and to a lesser extent hepato-splanchnic blood flow (-9% and -14%, respectively). The arterial-portal vein lactate gradient was not significantly affected by vasopressin. Postoperative serum creatinine was not affected by vasopressin. Short-term low to moderate infusion rates of vasopressin induced a splanchnic vasoconstriction without metabolic signs of splanchnic hypoperfusion or subsequent renal impairment. Vasopressin caused a centralization of blood volume and increased cardiac output. Vasopressin does not lower portal or hepatic venous pressures in this clinical setting. © 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Efficacy and safety of strategies to preserve stable extracorporeal life support flow during simulated hypovolemia.

PubMed

Simons, A P; Lindelauf, A A M A; Ganushchak, Y M; Maessen, J G; Weerwind, P W

2014-01-01

Without volume-buffering capacity in extracorporeal life support (ELS) systems, hypovolemia can acutely reduce support flow. This study aims at evaluating efficacy and safety of strategies for preserving stable ELS during hypovolemia. Flow and/or pressure-guided servo pump control, a reserve-driven control strategy and a volume buffer capacity (VBC) device were evaluated with respect to pump flow, venous line pressure and arterial gaseous microemboli (GME) during simulated normovolemia and hypovolemia. Normovolemia resulted in a GME-free pump flow of 3.1 ± 0.0 L/min and a venous line pressure of -10 ± 1 mmHg. Hypovolemia without servo pump control resulted in a GME-loaded flow of 2.3 ± 0.4 L/min with a venous line pressure of -114 ± 52 mmHg. Servo control resulted in an unstable and GME-loaded flow of 1.5 ± 1.2 L/min. With and without servo pump control, the VBC device stabilised flow (SD = 0.2 and 0.0 L/min, respectively) and venous line pressure (SD=51 and 4 mmHg, respectively) with near-absent GME activity. Reserve-driven pump control combined with a VBC device restored a near GME-free flow of 2.7 ± 0.0 L/min with a venous line pressure of -9 ± 0 mmHg. In contrast to a reserve-driven pump control strategy combined with a VBC device, flow and pressure servo control for ELS show evident deficits in preserving stable and safe ELS flow during hypovolemia.

[Self-active physical thrombosis prophylaxis in the patients' bed with the Phlebostep: acceptance and measurement of venous blood flow in immobilized patients].

PubMed

Olivier, L C; Ostovan, D; Heywinkel, W; Kendoff, D; Wolfhard, U

2007-11-01

Despite the broad use of low molecular weight heparin, deep vein thrombosis is still a relevant risk for immobilized patients in orthopedic surgery. Patients can reduce this risk by active training exercises with a muscle pump. The aim of this study was to test the acceptance and effect of a self-developed training device to accelerate venous return as well as a technical optimization. The device was installed for in-patients in orthopedic and traumatology departments. A simple pillow-like device was developed, which can be positioned against the foot end of the patient's bed (Phlebostep). The device gives a sound-based feedback to the patient while pushing actively against it with complete ankle flexion. A digital integrated counter device allows direct feedback to the physician and nursing staff at any time. Initial testing including duplex sonography for venous flow measurements were done on 10 orthopedic in-patients. Prior testing on 7 healthy volunteers was carried out to define the effect of various amounts of pressure on the Phlebostep on the venous blood flow. Additionally, a questionnaire on the general acceptance and user-friendliness was filled out by 84 patients who had used the Phlebostep. The optimal pressure force was defined as 35 mmHg for further measurements. The venous flow measurements in the 10 postoperative patients revealed an increased venous blood flow in the affected leg by an average of 99.9%. Analysis of the questionnaire from the 84 patients showed a high degree of acceptance. In addition to the technical feasibility, this study showed that use of the Phlebostep resulted on average in a doubling of venous return. The increase of venous flow offers an additional effective device for thrombosis prophylaxis through patient's own active movements and is clearly superior to the use of devices such as antithrombosis stockings alone. The Phlebostep found a high degree of acceptance with the patients.

Two zero-flow pressure intercepts exist in autoregulating isolated skeletal muscle.

PubMed

Braakman, R; Sipkema, P; Westerhof, N

1990-06-01

The autoregulating vascular bed of the isolated canine extensor digitorum longus muscle was investigated for the possible existence of two positive zero-flow pressure axis intercepts, a tone-dependent one and a tone-independent one. An isolated preparation, perfused with autologous blood, was used to exclude effects of collateral flow and nervous and humoral regulation while autoregulation was left intact [mean autoregulatory gain 0.50 +/- 0.24 (SD)]. In a first series of experiments, the steady-state (zero flow) pressure axis intercept [mean 8.9 +/- 2.6 (SD) mmHg, tone independent] and the instantaneous (zero flow) pressure axis intercept [mean 28.5 +/- 9.9 (SD) mmHg, tone dependent] were determined as a function of venous pressure (range: 0-45 mmHg) and were independent of venous pressure until the venous pressure exceeded their respective values. Beyond this point the relations between the venous pressure and the steady-state and instantaneous pressure axis intercept followed the line of identity. The findings agree with the predictions of the vascular waterfall model. In a second series it was shown by means of administration of vasoactive drugs that the instantaneous pressure axis intercept is tone dependent, whereas the steady-state pressure axis intercept is not. It is concluded that there is a (proximal) tone-dependent zero-flow pressure at the arteriolar level and a (distal) tone-independent zero-flow pressure at the venous level.

Time-resolved magnetic resonance angiography (MRA) at 3.0 Tesla for evaluation of hemodynamic characteristics of vascular malformations: description of distinct subgroups.

PubMed

Hammer, Simone; Uller, Wibke; Manger, Florentine; Fellner, Claudia; Zeman, Florian; Wohlgemuth, Walter A

2017-01-01

Quantitative evaluation of hemodynamic characteristics of arteriovenous and venous malformations using time-resolved magnetic resonance angiography (MRA) at 3.0 Tesla. Time-resolved MRA with interleaved stochastic trajectories (TWIST) at 3.0 Tesla was studied in 83 consecutive patients with venous malformations (VM) and arteriovenous malformations (AVM). Enhancement characteristics were calculated as percentage increase of signal intensity above baseline over time. Maximum percentage signal intensity increase (signal max ), time intervals between onset of arterial enhancement and lesion enhancement (t onset ), and time intervals between beginning of lesion enhancement and maximum percentage of lesion enhancement (t max ) were analyzed. All AVMs showed a high-flow hemodynamic pattern. Two significantly different (p < 0.001) types of venous malformations emerged: VMs with arteriovenous fistulas (AVF) (median signal max 737 %, IQR [interquartile range] = 511 - 1182 %; median t onset 5 s, IQR = 5 - 10 s; median t max 35 s, IQR = 26 - 40 s) and without AVFs (median signal max 284 %, IQR = 177-432 %; median t onset 23 s, IQR = 15 - 30 s; median t max 60 s, IQR = 55 - 75 s). Quantitative evaluation of time-resolved MRA at 3.0 Tesla provides hemodynamic characterization of vascular malformations. VMs can be subclassified into two hemodynamic subgroups due to presence or absence of AVFs. • Time-resolved MRA at 3.0 Tesla provides quantitative hemodynamic characterization of vascular malformations. • Malformations significantly differ in time courses of enhancement and signal intensity increase. • AVMs show a distinctive high-flow hemodynamic pattern. • Two significantly different types of VMs emerged: VMs with and without AVFs.

Vasopressin and nitroglycerin decrease portal and hepatic venous pressure and hepato-splanchnic blood flow.

PubMed

Wisén, E; Svennerholm, K; Bown, L S; Houltz, E; Rizell, M; Lundin, S; Ricksten, S-E

2018-03-26

Various methods are used to reduce venous blood pressure in the hepato-splanchnic circulation, and hence minimise blood loss during liver surgery. Previous studies show that combination of vasopressin and nitroglycerin reduces portal pressure and flow in patients with portal hypertension, and in this study we investigated this combination in patients with normal portal pressure. In all, 13 patients were studied. Measurements were made twice to confirm baseline (C1 and BL), during vasopressin infusion 4.8 U/h (V), and during vasopressin infusion combined with nitroglycerin infusion (V + N). Portal venous pressure (PVP), hepatic venous pressure (HVP), central haemodynamics and arterial and venous blood gases were obtained at each measuring point, and portal (splanchnic) and hepato-splanchnic blood flow changes were calculated. Vasopressin alone did not affect PVP, whereas HVP increased slightly. In combination with nitroglycerin, PVP decreased from 10.1 ± 1.6 to 8.9 ± 1.3 mmHg (P < 0.0001), and HVP decreased from 7.9 ± 1.9 to 6.2 ± 1.3 mmHg (P = 0.001). Vasopressin reduced portal blood flow by 47 ± 19% and hepatic venous flow by 11 ± 18%, respectively. Addition of nitroglycerin further reduced portal- and hepatic flow by 55 ± 13% and 30 ± 13%, respectively. Vasopressin alone had minor effects on central haemodynamics, whereas addition of nitroglycerin reduced cardiac index (3.2 ± 0.7 to 2.7 ± 0.5; P < 0.0001). The arterial-portal vein lactate gradient was unaffected. The combination of vasopressin and nitroglycerin decreases portal pressure and hepato-splanchnic blood flow, and could be a potential treatment to reduce bleeding in liver resection surgery. © 2018 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Arterial supply, venous drainage and collateral circulation in the nose of the anaesthetized dog.

PubMed Central

Lung, M A; Wang, J C

1987-01-01

1. In pentobarbitone-anaesthetized dogs, nasal blood flows were measured with electromagnetic flow sensors. 2. The terminal internal maxillary artery was found to supply 22 +/- 2.2 ml min-1 (one side) to the nasal mucosa via the sphenopalatine and major palatine branches; the artery was found to receive multiple supply routes from common carotid, vertebral and subclavian arteries. 3. Nasal mucosa was found to receive collateral flow from contralateral terminal internal maxillary artery (about 5 to 10% of normal flow) and branches of subclavian arteries (about 36% of normal flow). 4. Nasal mucosa was found to have two venous systems: the low-flow (12 +/- 1.0 ml min-1; both sides) and low-pressure (7 +/- 0.6 mmHg) sphenopalatine veins draining the posterior nasal cavity and the high-flow (30 +/- 1.4 ml min-1; both sides) and high-pressure (17 +/- 1.0 mmHg) dorsal nasal veins draining the anterior nasal cavity. 5. PO2 of nasal venous blood was found to range from 62 +/- 2.9 mmHg to 65 +/- 3.4 mmHg. During nitrogen challenge to the nose, the sphenopalatine venous PO2 dropped to 35 +/- 3.0 mmHg while the dorsal nasal venous PO2 remained unchanged, suggesting that the sphenopalatine veins were responsible for draining capillary flow and dorsal nasal veins arteriovenous anastomotic flow as well. 6. Microscopic examination of the vascular casts confirmed that arteriovenous anastomoses were located only in the anterior nasal cavity. Images Fig. 5 Plate 1 Plate 2 PMID:3443958

Neuromuscular electrical stimulation and an ottoman-type seat effectively improve popliteal venous flow in a sitting position.

PubMed

Morita, Hironobu; Abe, Chikara; Tanaka, Kunihiko; Shiratori, Mitsuo; Oguri, Masato; Shiga, Toshikazu

2006-04-01

The aim of this study was to examine the effects of the sitting posture on the lower limb venous flow and to explore the beneficial effects of neuromuscular electrical stimulation (NMES) and an ottoman-type seat on the venous flow. Healthy adult volunteers without a history of lower limb surgery or thromboembolism were recruited, and the flow velocity, cross-sectional area, and flow volume of the popliteal vein were measured using Doppler ultrasound. A posture change from the prone position to the sitting position on the ottoman-type seat decreased the flow velocity and increased the cross-sectional area of the popliteal vein, and the flow volume was not altered over 120 min. The flow velocity was further decreased, and the cross-sectional area was further increased by subjects sitting on a regular driving seat when compared with the values obtained with an ottoman-type seat. The popliteal flow velocity in the NMES leg was significantly higher than in the non-NMES leg throughout the 120-min testing in the sitting position, but no difference in the cross-sectional area was found between the NMES and the non-NMES legs. Thus lower limb venous stasis elicited by the sitting posture was improved by the ottoman-type seat and NMES.

High-Flow Arterio-Hepatic Venous Shunt in Hepatocellular Carcinoma: Use of Multi-Electrode Radiofrequency for Shunt Obliteration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pua, Uei, E-mail: druei@yahoo.com

2015-10-15

Intra-tumoral arterio-hepatic venous shunting (AHVS) poses an impediment to transarterial chemoembolization of liver tumors. Not only does it present a potential hazard for systemic shunting and embolization, but also the altered flow dynamics may also result in poor delivery of drug/embolics to the target tumor bed. Current available techniques to overcome AVHS include arterial embolization (particles, coils, glue, etc.) or temporary venous occlusion using balloons. We hereby illustrate the use of radiofrequency ablation to obliterate a complex AHVS consisting of a varix-like venous aneurysm.

What determines blood vessel structure? Genetic prespecification vs. hemodynamics.

PubMed

Jones, Elizabeth A V; le Noble, Ferdinand; Eichmann, Anne

2006-12-01

Vascular network remodeling, angiogenesis, and arteriogenesis play an important role in the pathophysiology of ischemic cardiovascular diseases and cancer. Based on recent studies of vascular network development in the embryo, several novel aspects to angiogenesis have been identified as crucial to generate a functional vascular network. These aspects include specification of arterial and venous identity in vessels and network patterning. In early embryogenesis, vessel identity and positioning are genetically hardwired and involve neural guidance genes expressed in the vascular system. We demonstrated that, during later stages of embryogenesis, blood flow plays a crucial role in regulating vessel identity and network remodeling. The flow-evoked remodeling process is dynamic and involves a high degree of vessel plasticity. The open question in the field is how genetically predetermined processes in vessel identity and patterning balance with the contribution of blood flow in shaping a functional vascular architecture. Although blood flow is essential, it remains unclear to what extent flow is able to act on the developing cardiovascular system. There is significant evidence that mechanical forces created by flowing blood are biologically active within the embryo and that the level of mechanical forces and the type of flow patterns present in the embryo are able to affect gene expression. Here, we highlight the pivotal role for blood flow and physical forces in shaping the cardiovascular system.

The unsuitability of implantable Doppler probes for the early detection of renal vascular complications – a porcine model for prevention of renal transplant loss

PubMed Central

Jespersen, Bente; Møldrup, Ulla; Keller, Anna K.

2017-01-01

Background Vascular occlusion is a rare, but serious complication after kidney transplantation often resulting in graft loss. We therefore aimed to develop an experimental porcine model for stepwise reduction of the renal venous blood flow and to compare an implantable Doppler probe and microdialysis for fast detection of vascular occlusion. Methods In 20 pigs, implantable Doppler probes were placed on the renal artery and vein and a microdialysis catheter was placed in the renal cortex. An arterial flowprobe served as gold standard. Following two-hour baseline measurements, the pigs were randomised to stepwise venous occlusion, complete venous occlusion, complete arterial occlusion or controls. Results All parameters were stable through baseline measurements. Glutamate and lactate measured by microdialysis increased significantly (p = 0.02 and p = 0.03 respectively) 30 minutes after a 2/3 (66%) reduction in renal blood flow. The implantable Doppler probe was not able to detect flow changes until there was total venous occlusion. Microdialysis detected changes in local metabolism after both arterial and venous occlusion; the implantable Doppler probe could only detect vascular occlusions on the vessel it was placed. Conclusions We developed a new model for stepwise renal venous blood flow occlusion. Furthermore, the first comparison of the implantable Doppler probe and microdialysis for detection of renal vascular occlusions was made. The implantable Doppler probe could only detect flow changes after a complete occlusion, whereas microdialysis detected changes earlier, and could detect both arterial and venous occlusion. Based on these results, the implantable Doppler probe for early detection of vascular occlusions cannot be recommended. PMID:28542429

Blunted postprandial reaction of portal venous flow in chronic liver disease, assessed with duplex Doppler: significance for prognosis.

PubMed

de Vries, P J; de Hooge, P; Hoekstra, J B; van Hattum, J

1994-12-01

To establish the effects of a meal on portal venous flow and the prognostic value of this parameter, 46 patients with chronic liver disease and 28 healthy subjects were examined with duplex Doppler before and after a meal. The measurements were completed in 40 patients and 21 healthy subjects. Postprandial portal venous diameter, blood velocity and quantitative flow were measured for 60 min. Mean baseline values were: 11.4 mm versus 10.2 mm (p = 0.019), 10.8 cm.s-1 versus 13.4 cm.s-1 (p = 0.015) and 668 ml.min-1 versus 646 ml.min-1 (p = 0.7) respectively. Spleen size was 15.0 cm versus 10.6 cm (p = 0.0001) respectively. Postprandial diameter, velocity and flow increased significantly in patients and controls (p = 0.0001 for all). Mean postprandial flow could best be described by a polynomial equation with a parabolic curve. Patients' curves were more blunted than controls', with significantly different regression constants (p = 0.025 and p = 0.029). All subjects were followed up for survival and variceal haemorrhage. The mean follow-up time was 47 months. Early maximum postprandial velocity (p = 0.041) and large spleen size (p = 0.002) were significantly related to an unfavourable prognosis for survival. Early maximum velocity was also related to increased variceal haemorrhage. This study shows that postprandial portal venous flow is blunted in patients with chronic liver disease. Postprandial portal venous flow may have prognostic significance.

Systemic venous drainage: can we help Newton?

PubMed

Corno, Antonio F

2007-06-01

In recent years substantial progress occurred in the techniques of cardiopulmonary bypass, but the factor potentially limiting the flexibility of cardiopulmonary bypass remains the drainage of the systemic venous return. In the daily clinical practice of cardiac surgery, the amount of systemic venous return on cardiopulmonary bypass is directly correlated with the amount of the pump flow. As a consequence, the pump flow is limited by the amount of venous return that the pump is receiving. On cardiopulmonary bypass the amount of venous drainage depends upon the central venous pressure, the height differential between patient and inlet of the venous line into the venous reservoir, and the resistance in the venous cannula(s) and circuit. The factors determining the venous return to be taken into consideration in cardiac surgery are the following: (a) characteristics of the individual patient; (b) type of planned surgical procedure; (c) type of venous cannula(s); (d) type of circuit for cardiopulmonary bypass; (e) strategy of cardiopulmonary bypass; (f) use of accessory mechanical systems to increased the systemic venous return. The careful pre-operative evaluation of all the elements affecting the systemic venous drainage, including the characteristics of the individual patient and the type of required surgical procedure, the choice of the best strategy of cardiopulmonary bypass, and the use of the most advanced materials and tools, can provide a systemic venous drainage substantially better than what it would be allowed by the simple "Law of universal gravitation" by Isaac Newton.

Recurrent High-Flow Arterio-Venous Malformation of the Thyroid Gland.

PubMed

Borchert, D H; Massmann, A; Kim, Y J; Bader, C A; Wolf, G; Eisele, R; Minko, P; Bücker, A; Glanemann, M

2015-09-01

Vascular malformations and hemangiomas of the thyroid gland are rare disorders. The first case of a patient with recurrent high-flow arterio-venous malformation of the right thyroid gland involving the right endolarynx is presented. In June 2013, a 42-year-old female patient presented to the surgical department with recurrent hoarseness and a soft, vibrating mass on the right side of her neck. In 1993, she underwent right subtotal hemithyroidectomy with embolization on the day before surgery for a high-flow arterio-venous malformation of the thyroid gland. Diagnostic work-up in 2013 demonstrated a complex recurrent high-flow arterio-venous malformation on the right side of her neck involving the endolarynx. Full function of the right vocal fold could not be ascertained. The lesion was embolized again and excised the following day. Intraoperative gross bleeding and scar tissue prevented visualization and monitoring of the recurrent laryngeal nerve. Gross bleeding was also noted on hemithyroidectomy after embolization in 1993. No therapy was needed for the endolaryngeal part of the lesion. Histology showed large arterio-venous malformations with thyroid tissue. She remains well without signs of recurrence 18 month later but with a definitive voice handicap. This is the first report of a recurrent high-flow arterio-venous malformation originally developing from the right thyroid gland involving the right endolarynx. Counseling, diagnostic, and therapeutic work-up of the patient was possible only with an interdisciplinary team. The endolaryngeal part of the hemangioma dried out after embolization and completion hemithyroidectomy. Her hoarseness has greatly improved but a definitive voice handicap remains. High-flow arterio-venous malformations of the thyroid gland are a rare disease, and recurrent lesions have not been reported. Interdisciplinary management of these patients is mandatory due to the complex nature of the underlying pathology. Recurrence might develop after long free intervals.

The use of micro-/milli-fluidics to better understand the mechanisms behind deep venous thrombosis

NASA Astrophysics Data System (ADS)

Schofield, Zoe; Alexiadis, Alessio; Brill, Alexander; Nash, Gerard; Vigolo, Daniele

2016-11-01

Deep venous thrombosis (DVT) is a dangerous and painful condition in which blood clots form in deep veins (e.g., femoral vein). If these clots become unstable and detach from the thrombus they can be delivered to the lungs resulting in a life threatening complication called pulmonary embolism (PE). Mechanisms of clot development in veins remain unclear but researchers suspect that the specific flow patterns in veins, especially around the valve flaps, play a fundamental role. Here we show how it is now possible to mimic the current murine model by developing micro-/milli-fluidic experiments. We exploited a novel detection technique, ghost particle velocimetry (GPV), to analyse the velocity profiles for various geometries. These vary from regular microfluidics with a rectangular cross section with a range of geometries (mimicking the presence of side and back branches in veins, closed side branch and flexible valves) to a more accurate venous representation with a 3D cylindrical geometry obtained by 3D printing. In addition to the GPV experiments, we analysed the flow field developing in these geometries by using computational fluid dynamic simulations to develop a better understanding of the mechanisms behind DVT. ZS gratefully acknowledges financial support from the EPSRC through a studentship from the Sci-Phy-4-Health Centre for Doctoral Training (EP/L016346/1).

Spatial interaction between tissue pressure and skeletal muscle perfusion during contraction.

PubMed

van Donkelaar, C C; Huyghe, J M; Vankan, W J; Drost, M R

2001-05-01

The vascular waterfall theory attributes decreased muscle perfusion during contraction to increased intramuscular pressure (P(IM)) and concomitant increase in venous resistance. Although P(IM) is distributed during contractions, this theory does not account for heterogeneity. This study hypothesises that pressure heterogeneity could affect the interaction between P(IM) rise and perfusion. Regional tissue perfusion during submaximum (100kPa) tetanic contraction is studied, using a finite element model of perfused contracting skeletal muscle. Capillary flow in muscles with one proximal artery and vein (SIM(1)) and with an additional distal artery and vein (SIM(2)) is compared. Blood flow and pressures at rest and P(IM) during contraction ( approximately 25kPa maximally) are similar between simulations, but capillary flow and venous pressure differ. In SIM(2), venous pressure and capillary flow correspond to P(IM) distribution, whereas capillary flow in SIM(1) is less than 10% of flow in SIM(2), in the muscle half without draining vein. This difference is caused by a high central P(IM), followed by central venous pressure rise, in agreement with the waterfall theory. The high central pressure (SIM(1)), obstructs outflow from the distal veins. Distal venous pressure rises until central blood pressure is reached, although local P(IM) is low. Adding a distal vein (SIM(2)) restores the perfusion. It is concluded that regional effects contribute to the interaction between P(IM) and perfusion during contraction. Unlike stated by the vascular waterfall theory, venous pressure may locally exceed P(IM). Although this can be explained by the principles of this theory, the theory does not include this phenomenon as such.

Forearm vasodilatation following release of venous congestion

PubMed Central

Caro, C. G.; Foley, T. H.; Sudlow, M. F.

1970-01-01

1. The volume rate of forearm blood flow was measured with a mercury-in-rubber strain gauge, or with a water-filled plethysmograph, from 1 sec after termination of a 2-3 min period of venous congestion. 2. When congesting pressure had been less than 18 mm Hg, average post-congestion flow (five subjects) was constant during approx. 10 sec and not significantly different from resting flow. 3. When congesting pressure had been 30 mm Hg, average post-congestion flow (eight subjects) was 26% higher than resting, during 3-4 sec after release of congestion, but rose to 273% of resting during 4-6 sec after release of congestion. 4. In other studies forearm vascular resistance had been found normal or increased during such venous congestion, and theoretical studies here indicated that passive mechanical factors could not account for the delayed occurrence of high post-congestion flow. 5. It appears, therefore, that the forearm vascular bed dilates actively shortly after release of substantial venous congestion. It would seem more likely that a myogenic mechanism, rather than a metabolic one, is responsible. PMID:5532541

PARACENTRAL ACUTE MIDDLE MACULOPATHY IN A PERIVENULAR FERN-LIKE DISTRIBUTION WITH EN FACE OPTICAL COHERENCE TOMOGRAPHY.

PubMed

Garrity, Sean T; Tseng, Victoria L; Sarraf, David

2017-11-22

To report a case of central retinal vein occlusion resulting in a perivenular pattern of paracentral acute middle maculopathy lesions best identified with en face optical coherence tomography (OCT). Retrospective case report. Optos ultra-widefield fluorescein angiography, spectral domain OCT, en face OCT, and OCT angiography were performed. A 41-year-old man presented with decreased vision in the right eye for 2 weeks. Funduscopic examination of the affected right eye was notable for subtle retinal whitening in the macula, mild retinal venous dilation and tortuosity, and few scattered retinal dot and blot hemorrhages consistent with an acute central retinal vein occlusion. Widefield fluorescein angiography demonstrated delayed arterial and venous filling but no evidence of significant peripheral retinal vascular ischemia. En face OCT segmented at the inner nuclear layer illustrated a remarkable and precise perivenular distribution of fern-like paracentral acute middle maculopathy with periarterial sparing, whereas en face OCT segmented at the outer nuclear layer demonstrated florid cystoid macular edema. At 6-week follow-up, OCT demonstrated patchy areas of atrophic inner nuclear layer and spontaneous resolution of the cystoid macular edema. Optical coherence tomography angiography at the level of the deep capillary plexus illustrated remarkable flow reduction of the deep capillary plexus in mainly a perivenular distribution. The authors report a case of a central retinal vein occlusion with mild retinal findings associated with a remarkable perivenular pattern of paracentral acute middle maculopathy with en face OCT. Follow-up OCT angiography demonstrated significant flow reduction of the deep capillary plexus in a perivenular pattern. The perivenular pattern of paracentral acute middle maculopathy lesions with en face OCT can be an important finding suggestive of a central retinal vein occlusion.

Computational modeling of venous sinus stenosis in idiopathic intracranial hypertension

PubMed Central

Levitt, Michael R; McGah, Patrick M; Moon, Karam; Albuquerque, Felipe C; McDougall, Cameron G; Kalani, M Yashar S; Kim, Louis J; Aliseda, Alberto

2016-01-01

Background and Purpose Idiopathic intracranial hypertension has been associated with dural venous sinus stenosis in some patients, but the hemodynamic environment of the dural venous sinuses has not been quantitatively described. Here, we present the first such computational fluid dynamics model using patient-specific blood pressure measurements. Materials and Methods Six patients with idiopathic intracranial hypertension and at least one stenosis or atresia at the transverse-sigmoid sinus junction underwent MRV followed by cerebral venography and manometry throughout the dural venous sinuses. Patient-specific computational fluid dynamics models were created using MRV anatomy, with venous pressure measurements as boundary conditions. Blood flow and wall shear stress were calculated for each patient. Results Computational models of dural venous sinuses were successfully reconstructed in all six patients with patient-specific boundary conditions. Three patients demonstrated a pathologic pressure gradient (≥ 8 mm Hg) across four dural venous sinus stenoses. Small sample size precludes statistical comparisons, but average overall flow throughout the dural venous sinuses of patients with pathologic pressure gradients was higher than in those without (1041.00 ± 506.52 vs. 358.00 ± 190.95 mL/min). Wall shear stress was also higher across stenoses in patients with pathologic pressure gradients (37.66 ± 48.39 vs 7.02 ± 13.60 Pa). Conclusion The hemodynamic environment of the dural venous sinuses can be computationally modeled using patient-specific anatomy and physiological measurements in patients with idiopathic intracranial hypertension. There was substantially higher blood flow and wall shear stress in patients with pathological pressure gradients. PMID:27197986

A Study to Determine the Evolution of Advances in Medical Technology Expected in the Next 25 Years and Possible Impacts on Coast Guard Operations and Support Programs.

DTIC Science & Technology

1980-05-01

abnormalities in pressure tracings of the systemic, the central venous or pulmonary arterial circulation. At some sites (especially the Latter-Day Saints...accurate measurement of central venous pressure has been by direct venous cannulation. However, a group of Swiss doctors has extended the principle of... venous stop flow pressure to develop a noninvasive method of measuring central venous pressure. The method consists of venous auscultation at the thoracic

Non-contact hemodynamic imaging reveals the jugular venous pulse waveform

NASA Astrophysics Data System (ADS)

Amelard, Robert; Hughson, Richard L.; Greaves, Danielle K.; Pfisterer, Kaylen J.; Leung, Jason; Clausi, David A.; Wong, Alexander

2017-01-01

Cardiovascular monitoring is important to prevent diseases from progressing. The jugular venous pulse (JVP) waveform offers important clinical information about cardiac health, but is not routinely examined due to its invasive catheterisation procedure. Here, we demonstrate for the first time that the JVP can be consistently observed in a non-contact manner using a photoplethysmographic imaging system. The observed jugular waveform was strongly negatively correlated to the arterial waveform (r = -0.73 ± 0.17), consistent with ultrasound findings. Pulsatile venous flow was observed over a spatially cohesive region of the neck. Critical inflection points (c, x, v, y waves) of the JVP were observed across all participants. The anatomical locations of the strongest pulsatile venous flow were consistent with major venous pathways identified through ultrasound.

Non-contact hemodynamic imaging reveals the jugular venous pulse waveform

PubMed Central

Amelard, Robert; Hughson, Richard L.; Greaves, Danielle K.; Pfisterer, Kaylen J.; Leung, Jason; Clausi, David A.; Wong, Alexander

2017-01-01

Cardiovascular monitoring is important to prevent diseases from progressing. The jugular venous pulse (JVP) waveform offers important clinical information about cardiac health, but is not routinely examined due to its invasive catheterisation procedure. Here, we demonstrate for the first time that the JVP can be consistently observed in a non-contact manner using a photoplethysmographic imaging system. The observed jugular waveform was strongly negatively correlated to the arterial waveform (r = −0.73 ± 0.17), consistent with ultrasound findings. Pulsatile venous flow was observed over a spatially cohesive region of the neck. Critical inflection points (c, x, v, y waves) of the JVP were observed across all participants. The anatomical locations of the strongest pulsatile venous flow were consistent with major venous pathways identified through ultrasound. PMID:28065933

To shunt or not to shunt? An experimental study comparing temporary vascular shunts and venous ligation as damage control techniques for vascular trauma.

PubMed

Marinho de Oliveira Góes Junior, Adenauer; de Campos Vieira Abib, Simone; de Seixas Alves, Maria Teresa; Venerando da Silva Ferreira, Paulo Sérgio; Carvalho de Andrade, Mariseth

2014-04-01

To evaluate vascular flow through temporary vascular shunts inserted into peripheral arteries and veins and the repercussion, on the arterial perfusion, of venous ligation and venous shunt insertion in an experimental model for damage control. Experimental study in pigs. Animals were distributed in 5 groups: group 1, right external iliac artery (EIA) shunting and right external iliac vein (EIV) ligation; group 2, right EIA shunting and right EIV shunting; group 3, right EIV ligation; group 4, right EIV shunting; group 5, no vascular shunting and no venous ligation. Flowmeters were used to measure vascular flow on right and left external iliac vessels, and blood samples were collected from the EIVs for biochemical analysis. A right anterior limb biopsy was performed before shock. Hemorrhagic shock was induced through the external right jugular vein, until the vascular flow through right iliac external artery shunt or right iliac external vein shunt (group 4) ceased or until the animal's death. After the end of the experiments, biopsies of bilateral hind limb were obtained for histologic analysis. For statistical analysis, Microsoft Office Excel 2007 and BioEstat 5.0 (2007) were used. In the absence of hemorrhagic shock, venous ligation (group 1) was associated with a 38.8% reduction (P < 0.05) and venous shunting with a 28.4% reduction on the vascular flow through the arterial shunt. When associated with hemorrhagic shock, the mean vascular flow on the right EIA was 13 mL/min and on the left EIA was 41.2 mL/min; on group 2, the right EIA flow was 8.5 mL/min and the left EIA flow was 8.1 mL/min. When associated with hemorrhagic shock, the pO2 was 25.8 mm Hg on right EIV and 33.8 mm Hg on the left EIV for group 1 (P < 0.05), whereas for group 2, the pO2 was 22.6 mm Hg on right EIV and 22.8 mm Hg on the left EIV. On group 1, serum potassium was 3.84 mEq/L on the right EIV and 3.96 mEq/L on the left EIV, whereas on group 2, it was 7.1 mEq/L on the right EIV and 5.88 mEq/L on the left EIV (P < 0.05). In the developed experimental model, venous shunting, when compared with venous ligation, offered less resistance to vascular flow through the arterial shunt and allowed a more efficient limb venous drainage than simple vein ligature. Copyright © 2014 Elsevier Inc. All rights reserved.

The effect of in-plane arterial curvature on blood flow and oxygen transport in arterio-venous fistulae

NASA Astrophysics Data System (ADS)

Iori, F.; Grechy, L.; Corbett, R. W.; Gedroyc, W.; Duncan, N.; Caro, C. G.; Vincent, P. E.

2015-03-01

Arterio-Venous Fistulae (AVF) are the preferred method of vascular access for patients with end stage renal disease who need hemodialysis. In this study, simulations of blood flow and oxygen transport were undertaken in various idealized AVF configurations. The objective of the study was to understand how arterial curvature affects blood flow and oxygen transport patterns within AVF, with a focus on how curvature alters metrics known to correlate with vascular pathology such as Intimal Hyperplasia (IH). If one subscribes to the hypothesis that unsteady flow causes IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto the outer-curvature of a curved artery. However, if one subscribes to the hypothesis that low wall shear stress and/or low lumen-to-wall oxygen flux (leading to wall hypoxia) cause IH within AVF, then the results suggest that in order to avoid IH, AVF should be formed via a vein graft onto a straight artery, or the inner-curvature of a curved artery. We note that the recommendations are incompatible—highlighting the importance of ascertaining the exact mechanisms underlying development of IH in AVF. Nonetheless, the results clearly illustrate the important role played by arterial curvature in determining AVF hemodynamics, which to our knowledge has been overlooked in all previous studies.

Experimental investigation of the effects of inserting a bovine venous valve in the inferior vena cava of Fontan circulation

NASA Astrophysics Data System (ADS)

Santhanakrishnan, Arvind; Johnson, Jacob; Kotz, Monica; Tang, Elaine; Khiabani, Reza; Yoganathan, Ajit; Maher, Kevin

2012-11-01

The Fontan procedure is a palliative surgery performed on patients with single ventricle (SV) congenital heart defects. The SV is used for systemic circulation and the venous return from the inferior vena cava (IVC) and superior vena cava (SVC) is routed to the pulmonary arteries (PA), resulting in a total cavopulmonary connection (TCPC). Hepatic venous hypertension is commonly manifested in the Fontan circulation, leading to long-term complications including liver congestion and cirrhosis. Respiratory intrathoracic pressure changes affect the venous return from the IVC to the PA. Using a physical model of an idealized TCPC, we examine placement of a unidirectional bovine venous valve within the IVC as a method of alleviating hepatic venous hypertension. A piston pump is used to provide pulsatility in the internal flow through the TCPC, while intrathoracic pressure fluctuations are imposed on the external walls of the model using a pair of linear actuators. When implanted in the extrathoracic position, the hepatic venous pressure is lowered from baseline condition. The effects of changing caval flow distribution and intrathoracic pressure on TCPC hemodynamics will be examined.

Acute Hemodynamic Effects of the Braslet-M Device on the International Space Station

NASA Technical Reports Server (NTRS)

Hamilton, Douglas R.; Barratt, Michael R.; Sargsyan, Ashot E.; Garcia, Kathleen M.; Ebert, Douglas; Martin, David; Dulchavsky, Scott A.; Duncan, J. Michael

2009-01-01

The Braslet-M occlusion device is prescribed for cosmonauts as a countermeasure for early phases of spaceflight to temporarily alleviate symptoms associated with the cephalad fluid shift. Using a multipurpose ultrasound (US) device onboard, we assessed the acute hemodynamic effects of the Bracelet-M device on a long duration International Space Station (ISS) crewmember. Methods A combination of just-in-time training and real-time remote expert assistance was used to conduct the imaging procedures. An HDI-5000 imager (Philips, Bothell, WA) was used, provided by the ISS Human Research Facility. Superficial femoral artery (SFA), femoral vein (FV) flow spectra were obtained at mid-thigh level. Left ventricle was imaged through the apical 4-chamber view, with Color M-Mode to measure propagation velocity (V (p)). After 10 minutes of Bracelet-M use, data collection was repeated. All data were transmitted in DICOM format to ground for analysis. Results With Braslet-M, cardiac V(p) slope decreased (56ms to 42ms). A stagnation signature in the FV was seen suggesting impeded flow (rouleaux formation, too-low-to-measure velocity, and increase in diameter). Quadri-phasic flow in SFA was seen both before and after Braslet-M application. Velocities in the SFA decreased with Braslet-M (65cm/sec to 52cm/sec) and so did the time velocity integrals (16.97 to 12.4); the flow pattern spoke of resistivity increase in the vascular bed. Conclusion In the long duration ISS crewmember we observed effects of lower extremity venous occlusion through both central and peripheral indicators. A part of circulating volume transferred to peripheral potential vascular space. Impediment to venous outflow was demonstrated objectively, with a commensurate change in the flow pattern of the main feeding artery. Central volume reduction caused lower V(p). Additional studies are warranted to determine the time course of the changes and the dynamics in interstitial fluid sequestration, as well as the safe levels and duration of the compression forces.

Determinants of systemic zero-flow arterial pressure.

PubMed

Brunner, M J; Greene, A S; Sagawa, K; Shoukas, A A

1983-09-01

Thirteen pentobarbital-anesthetized dogs whose carotid sinuses were isolated and perfused at a constant pressure were placed on total cardiac bypass. With systemic venous pressure held at 0 mmHg (condition 1), arterial inflow was stopped for 20 s at intrasinus pressures of 50, 125, and 200 mmHg. Zero-flow arterial pressures under condition 1 were 16.2 +/- 1.3 (SE), 13.8 +/- 1.1, and 12.5 +/- 0.8 mmHg, respectively. In condition 2, the venous outflow tube was clamped at the instant of stopping the inflow, causing venous pressure to rise. The zero-flow arterial pressures were 19.7 +/- 1.3, 18.5 +/- 1.4, and 16.4 +/- 1.2 mmHg for intrasinus pressures of 50, 125, and 200 mmHg, respectively. At all levels of intrasinus pressure, the zero-flow arterial pressure in condition 2 was higher (P less than 0.005) than in condition 1. In seven dogs, at an intrasinus pressure of 125 mmHg, epinephrine increased the zero-flow arterial pressure by 3.0 mmHg, whereas hexamethonium and papaverine decreased the zero-flow arterial pressure by 2 mmHg. Reductions in the hematocrit from 52 to 11% resulted in statistically significant changes (P less than 0.01) in zero-flow arterial pressures. Thus zero-flow arterial pressure was found to be affected by changes in venous pressure, hematocrit, and vasomotor tone. The evidence does not support the literally interpreted concept of the vascular waterfall as the model for the finite arteriovenous pressure difference at zero flow.

Interest of HYPR flow dynamic MRA for characterization of cerebral arteriovenous malformations: comparison with TRICKS MRA and catheter DSA.

PubMed

Dautry, Raphaël; Edjlali, Myriam; Roca, Pauline; Rabrait, Cécile; Wu, Yijing; Johnson, Kevin; Wieben, Olivier; Trystram, Denis; Rodriguez-Régent, Christine; Alshareef, Fawaz; Turski, Patrick; Meder, Jean-François; Naggara, Olivier; Oppenheim, Catherine

2015-11-01

HYPR flow is a 3D dynamic contrast-enhanced MRA technique providing isotropic sub-millimetre resolution with half-second temporal resolution. We compared HYPR flow and time-resolved imaging of contrast kinetics (TRICKS) MRA for the characterization of cerebral arteriovenous malformations (cAVMs), using catheter DSA as reference. Twenty-two patients underwent HYPR flow and TRICKS MRA within 15 days of DSA. HYPR flow and TRICKS datasets were reviewed separately by two readers for image quality, Spetzler-Martin grade, venous ectasia, and deep venous drainage. Image quality was better for HYPR flow than for TRICKS (narrower full width at half maximum; larger arterial diagnostic window; greater number of arterial frames, P ≤ 0.05). Using HYPR flow, inter-reader agreement was excellent for all cAVM characteristics. The agreement with DSA for the overall Spetzler-Martin grade was excellent for HYPR flow (ICC = 0.96 and 0.98, depending on the reader) and TRICKS (ICC = 0.82 and 0.95). In comparison to TRICKS, HYPR flow showed higher concordance with DSA for the identification of venous ectasia and deep venous drainage. Owing to an excellent agreement with DSA with respect to depiction of the vascular architecture of cAVMs, HYPR flow could be useful for the non-invasive characterization of cAVMs. • Dynamic MRA is used for cerebral AVM depiction and follow-up • HYPR flow is a new, highly-resolved dynamic MRA sequence • HYPR flow provides whole brain coverage • HYPR flow provides excellent agreement with the Spetzler-Martin grade • Compared to TRICKS MRA, HYPR flow improves cerebral AVM characterization.

Physiologic Pressure and Flow Changes During Parabolic Flight (Pilot Study)

NASA Technical Reports Server (NTRS)

Pantalos, George; Sharp, M. Keith; Mathias, John R.; Hargens, Alan R.; Watenpaugh, Donald E.; Buckey, Jay C.

1999-01-01

The objective of this study was to obtain measurement of cutaneous tissue perfusion central and peripheral venous pressure, and esophageal and abdominal pressure in human test subjects during parabolic flight. Hemodynamic data recorded during SLS-I and SLS-2 missions have resulted in the paradoxical finding of increased cardiac stroke volume in the presence of a decreased central venous pressure (CVP) following entry in weightlessness. The investigators have proposed that in the absence of gravity, acceleration-induced peripheral vascular compression is relieved, increasing peripheral vascular capacity and flow while reducing central and peripheral venous pressure, This pilot study seeks to measure blood pressure and flow in human test subjects during parabolic flight for different postures.

[Venous Doppler color echography: importance and inconveniences].

PubMed

Laroche, J P; Dauzat, M; Muller, G; Janbon, C

1993-01-01

Color Doppler is a technique which performs a real-time opacification of the vascular system with blue indicating reverse flow and red indicating forward flow (directional color coding). In venous pathology, the use of color Doppler improves significantly the anatomical evaluation of the inferior vena cava, the iliac vein, the deep femoral vein, and the sural system. Color Doppler facilitates the study of deep venous thrombosis (providing useful information to differentiate ancient from most recent thrombus) and also the study of post-thrombotic conditions (assessment of reverse flow, repermeation phenomena). Finally, color Doppler produces a better insight for the study of varicose veins, especially with regard to mapping, identification of communicante veins, and study of the external saphenous vein.

Experimental and numeric investigation of Impella pumps as cavopulmonary assistance for a failing Fontan.

PubMed

Haggerty, Christopher M; Fynn-Thompson, Francis; McElhinney, Doff B; Valente, Anne Marie; Saikrishnan, Neelakantan; Del Nido, Pedro J; Yoganathan, Ajit P

2012-09-01

This study sought to evaluate the performance of microaxial ventricular assist devices for the purposes of supporting failing Fontan physiology by decreasing central venous pressure. Three Abiomed Impella pumps (Abiomed, Inc, Danvers, Mass) were evaluated in a mock circulatory system of the Fontan circuit. The local response of pressures and flows to pump function was assessed as a function of pump speed and pulmonary vascular resistance at a high baseline central venous pressure. For one device, subsequent modeling studies were conducted using a lumped parameter model of the single ventricle circuit. The left ventricular devices (Impella 2.5, 5.0) were shown to be suboptimal as single device solutions for cavopulmonary support. The small area of these devices relative to vessel diameter led to significant flow recirculation without an obstructive separator in place. Furthermore, downstream pressure augmentation adversely affected the pressure in the superior vena cava. The use of 2 devices would be mandatory for successful support. The right-sided device (Impella RP), whose outflow was positioned in the left pulmonary artery, demonstrated decreased flow recirculation and did not impede superior caval venous flow. Although static pressure is still required to drive flow through the opposite lung, numeric modeling demonstrated the potential for modest but significant improvements in lowering the central venous pressure (2-8 mm Hg). Left-sided microaxial pumps are not well suited for cavopulmonary support because of severe flow recirculation and the need for multiple devices. The right-ventricular Impella device provides improved performance by directing flow into the pulmonary artery, resulting in modest decreases in central venous pressure. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

MR Elastography Can Be Used to Measure Brain Stiffness Changes as a Result of Altered Cranial Venous Drainage During Jugular Compression.

PubMed

Hatt, A; Cheng, S; Tan, K; Sinkus, R; Bilston, L E

2015-10-01

Compressing the internal jugular veins can reverse ventriculomegaly in the syndrome of inappropriately low pressure acute hydrocephalus, and it has been suggested that this works by "stiffening" the brain tissue. Jugular compression may also alter blood and CSF flow in other conditions. We aimed to understand the effect of jugular compression on brain tissue stiffness and CSF flow. The head and neck of 9 healthy volunteers were studied with and without jugular compression. Brain stiffness (shear modulus) was measured by using MR elastography. Phase-contrast MR imaging was used to measure CSF flow in the cerebral aqueduct and blood flow in the neck. The shear moduli of the brain tissue increased with the percentage of blood draining through the internal jugular veins during venous compression. Peak velocity of caudally directed CSF in the aqueduct increased significantly with jugular compression (P < .001). The mean jugular venous flow rate, amplitude, and vessel area were significantly reduced with jugular compression, while cranial arterial flow parameters were unaffected. Jugular compression influences cerebral CSF hydrodynamics in healthy subjects and can increase brain tissue stiffness, but the magnitude of the stiffening depends on the percentage of cranial blood draining through the internal jugular veins during compression—that is, subjects who maintain venous drainage through the internal jugular veins during jugular compression have stiffer brains than those who divert venous blood through alternative pathways. These methods may be useful for studying this phenomenon in patients with the syndrome of inappropriately low-pressure acute hydrocephalus and other conditions. © 2015 by American Journal of Neuroradiology.

Hepatic venous connection to a persistent inferior caval vein in left isomerism.

PubMed

Guenthard, J; Carvalho, J S; Anderson, R H; Rigby, M L

1990-09-01

In 22 cases of left atrial isomerism studied at the Brompton Hospital, four cases were found to have an unusual arrangement of the abdominal vessels. There was persistence of an inferior caval vein, partially anomalous hepatic venous connection and additional continuation of part of the venous return from the lower body through the azygos venous system. This venous pattern had surgical implications in our index case, since redirection of the inferior caval venous return was necessary.

Identification of the Upward Movement of Human CSF In Vivo and its Relation to the Brain Venous System.

PubMed

Dreha-Kulaczewski, Steffi; Joseph, Arun A; Merboldt, Klaus-Dietmar; Ludwig, Hans-Christoph; Gärtner, Jutta; Frahm, Jens

2017-03-01

CSF flux is involved in the pathophysiology of neurodegenerative diseases and cognitive impairment after traumatic brain injury, all hallmarked by the accumulation of cellular metabolic waste. Its effective disposal via various CSF routes has been demonstrated in animal models. In contrast, the CSF dynamics in humans are still poorly understood. Using novel real-time MRI, forced inspiration has been identified recently as a main driving force of CSF flow in the human brain. Exploiting technical advances toward real-time phase-contrast MRI, the current work analyzed directions, velocities, and volumes of human CSF flow within the brain aqueduct as part of the internal ventricular system and in the spinal canal during respiratory cycles. A consistent upward CSF movement toward the brain in response to forced inspiration was seen in all subjects at the aqueduct, in 11/12 subjects at thoracic level 2, and in 4/12 subjects at thoracic level 5. Concomitant analyses of CSF dynamics and cerebral venous blood flow, that is, in epidural veins at cervical level 3, uniquely demonstrated CSF and venous flow to be closely communicating cerebral fluid systems in which inspiration-induced downward flow of venous blood due to reduced intrathoracic pressure is counterbalanced by an upward movement of CSF. The results extend our understanding of human CSF flux and open important clinical implications, including concepts for drug delivery and new classifications and therapeutic options for various forms of hydrocephalus and idiopathic intracranial hypertension. SIGNIFICANCE STATEMENT Effective disposal of brain cellular waste products via CSF has been demonstrated repeatedly in animal models. However, CSF dynamics in humans are still poorly understood. A novel quantitative real-time MRI technique yielded in vivo CSF flow directions, velocities, and volumes in the human brain and upper spinal canal. CSF moved upward toward the head in response to forced inspiration. Concomitant analysis of brain venous blood flow indicated that CSF and venous flux act as closely communicating systems. The finding of a human CSF-venous network with upward CSF net movement opens new clinical concepts for drug delivery and new classifications and therapeutic options for various forms of hydrocephalus and ideopathic intracranial hypertension. Copyright © 2017 the authors 0270-6474/17/372395-08$15.00/0.

Automated measurement and classification of pulmonary blood-flow velocity patterns using phase-contrast MRI and correlation analysis.

PubMed

van Amerom, Joshua F P; Kellenberger, Christian J; Yoo, Shi-Joon; Macgowan, Christopher K

2009-01-01

An automated method was evaluated to detect blood flow in small pulmonary arteries and classify each as artery or vein, based on a temporal correlation analysis of their blood-flow velocity patterns. The method was evaluated using velocity-sensitive phase-contrast magnetic resonance data collected in vitro with a pulsatile flow phantom and in vivo in 11 human volunteers. The accuracy of the method was validated in vitro, which showed relative velocity errors of 12% at low spatial resolution (four voxels per diameter), but was reduced to 5% at increased spatial resolution (16 voxels per diameter). The performance of the method was evaluated in vivo according to its reproducibility and agreement with manual velocity measurements by an experienced radiologist. In all volunteers, the correlation analysis was able to detect and segment peripheral pulmonary vessels and distinguish arterial from venous velocity patterns. The intrasubject variability of repeated measurements was approximately 10% of peak velocity, or 2.8 cm/s root-mean-variance, demonstrating the high reproducibility of the method. Excellent agreement was obtained between the correlation analysis and radiologist measurements of pulmonary velocities, with a correlation of R2=0.98 (P<.001) and a slope of 0.99+/-0.01.

Regional Blood Volume and Peripheral Blood Flow in the Postural Tachycardia Syndrome

PubMed Central

Stewart, Julian M.; Montgomery, Leslie D.

2015-01-01

Variants of postural tachycardia syndrome (POTS) are associated with increased (“high flow” POTS, HFP), decreased (“low flow POTS”, LFP) and normal (“normal flow POTS”, NFP) blood flow measured in the lower extremities while supine. We propose that postural tachycardia is related to thoracic hypovolemia during orthostasis but that the patterns of peripheral blood flow relate to different mechanisms for thoracic hypovolemia. We studied 37 POTS patients aged 14-21 years: 14 LFP, 15 NFP and 8 HFP patients and 12 healthy control subjects. Peripheral blood flow was measured supine by venous occlusion strain gauge plethysmography of the forearm and calf in order to subgroup patients. Using indocyanine green techniques we showed decreased cardiac index (CI) and increased total peripheral resistance (TPR) in LFP, increased CI and decreased TPR in HFP, and unchanged CI and TPR in NFP while supine compared to control subjects. Blood volume tended to be decreased in LFP compared to control subjects. We used impedance plethysmography to assess regional blood volume redistribution during upright tilt. Thoracic blood volume decreased while splanchnic, pelvic and leg blood volumes increased for all subjects during orthostasis, but were markedly lower than control for all POTS groups. Splanchnic volume was increased in NFP and LFP. Pelvic blood volume was increased in HFP only. Calf volume was increased above control in HFP and LFP. The results support the hypothesis of [at least] three pathophysiologic variants of POTS distinguished by peripheral blood flow related to characteristic changes in regional circulations. The data demonstrate enhanced thoracic hypovolemia during upright tilt and confirm that POTS is related to inadequate cardiac venous return during orthostasis. PMID:15117717

The Need of Slanted Side Holes for Venous Cannulae

PubMed Central

Park, Joong Yull

2012-01-01

Well-designed cannulae must allow good flow rate and minimize nonphysiologic load. Venous cannulae generally have side holes to prevent the rupture of blood vessel during perfusion. Optimizing side hole angle will yield more efficient and safe venous cannulae. A numerical modeling was used to study the effect of the angle (0°–45°) and number (0–12) of side holes on the performance of cannulae. By only slanting the side holes, it increases the flow rate up to 6% (in our models). In addition, it was found that increasing the number of side holes reduces the shear rate up to 12% (in our models). A new parameter called “penetration depth” was introduced to describe the interfering effect of stream jets from side holes, and the result showed that the 45°-slanted side holes caused minimum interfering for the flow in cannula. Our quantitative hemodynamic analysis study provides important guidelines for venous cannulae design. PMID:22291856

Pattern of venous collateral development after splenic vein occlusion in an extended Whipple procedure : comparison with collateral vein pattern in cases of sinistral portal hypertension.

PubMed

Strasberg, Steven M; Bhalla, Sanjeev; Sanchez, Luis A; Linehan, David C

2011-11-01

The risks of developing sinistral portal hypertension as a result of occlusion of the splenic vein close to its termination during a Whipple procedure are unclear. Our purpose was to compare the pattern of venous collateral development after splenic vein ligation in an extended Whipple procedure with the pattern of collateral development in cases of sinistral portal hypertension. Five patients underwent an extended Whipple procedure in which the splenic vein was divided and not reconstructed. Six to eight months later detailed mapping of venous return from the spleen was determined by contrast-enhanced multidetector computed tomography or in one case by 3D contrast-enhanced MRI. Spleen size and length of residual patent splenic vein were also measured. The literature on sinistral portal hypertension was evaluated to ascertain whether the venous collateral pattern in cases of left-sided portal hypertension was similar to the pattern that developed when the splenic vein was ligated at its termination in the Whipple procedure. A length of splenic vein remained patent in all five patients, measuring 4.5 to 11.5 cm from the spleen. Splenomegaly did not develop. Blood returned from the spleen by multiple collaterals including collaterals in the omentum and mesocolon. These types of collaterals do not develop in sinistral portal hypertension, nor is residual patent splenic vein seen. Ligation of the splenic vein close to its termination in five patients resulted in a pattern of venous return different from patients that have developed left-sided portal hypertension.

Calf pump activity influencing venous hemodynamics in the lower extremity.

PubMed

Recek, Cestmir

2013-03-01

Calf muscle pump is the motive force enhancing return of venous blood from the lower extremity to the heart. It causes displacement of venous blood in both vertical and horizontal directions, generates ambulatory pressure gradient between thigh and lower leg veins, and bidirectional streaming within calf perforators. Ambulatory pressure gradient triggers venous reflux in incompetent veins, which induces ambulatory venous hypertension in the lower leg and foot. Bidirectional flow in calf perforators enables quick pressure equalization between deep and superficial veins of the lower leg; the outward (into the superficial veins) oriented component of the bidirectional flow taking place during calf muscle contraction is no pathological reflux but a physiological centripetal flow streaming via great saphenous vein into the femoral vein. Calf perforators are communicating channels between both systems making them conjoined vessels; they are not involved in the generation of pathological hemodynamic situations, nor do they cause ambulatory venous hypertension. The real cause why recurrences develop has not as yet been cleared. Pressure gradient arising during calf pump activity between the femoral vein and the saphenous remnant after abolition of saphenous reflux triggers biophysical and biochemical events, which might induce recurrence. Thus, abolition of saphenous reflux removes the hemodynamic disturbance, but at the same time it generates precondition for reflux recurrence and for the comeback of the previous pathological situation; this chain of events has been called hemodynamic paradox.

[Functional status of musculo-venous pump of shin in various types of of operations for varicose disease].

PubMed

Boítsov, N I; Evtikhov, R M; Potapov, N A

1997-01-01

Functional conditions of the muscular-venous pump of the shin were studied in 280 patients with varicose veins before surgery, in 164 patients in remote terms after various operations and in 54 healthy subjects on the base of guantitative plethysmographic estimation of hemodynamic parameters. At the stage of compensation all volume indices of the bloodflow were close to normal values; in the stage of decompensation the substantial increase of volume effectiveness and volume flow velocity was observed at carrying out the test for direct deep blood flow when walking. It was determined that in natural condition for venous hemodynamics the adaptation mechanisms of musculo-venous pump were not realized. The operation of Linton upsets the function of musculo-venous pump of the shin. The Kocket operation does not eliminate the pathologic overload when working due to insufficient radicalism in liquidation of perforation escape (steal phenomena). The subfascial ligation of perforating veins of the shin through the minor approach, used in clinical practice, proved to be sufficiently radical and does not impair the function of the musculo-venous pump of the shin.

The effects of catecholamines and adrenoceptor blocking drugs on the canine peripheral lymph flow.

PubMed Central

De Micheli, P; Glässer, A H

1975-01-01

Blood flow through the femoral artery, lymph flow in a lymphatic vessel in the femoral triangle and metatarsal distal venous pressure were measured simultaneously in a canine moving hind limb. 2. Low intra-arterial doses of adrenaline and noradrenaline increased lymph flow even in the presence of marked arterial vasoconstriction. In contrast, isoprenaline increased arterial blood flow without affecting lymph flow rate. 3. Phenoxybenzamine, dihydroergotoxine, and nicergoline did not inhibit the lymphatic flow increase induced by adrenaline at doses active on arterial or venous vascular alpha-adrenoceptors. 4. Propranolol given intra-arterially into animals pretreated with alpha-adrenoceptor blocking agents restored the vasoconstrictor effect of adrenaline (reversal of adrenaline reversal). PMID:238702

MRI Evidence for Altered Venous Drainage and Intracranial Compliance in Mild Traumatic Brain Injury

PubMed Central

Pomschar, Andreas; Koerte, Inga; Lee, Sang; Laubender, Ruediger P.; Straube, Andreas; Heinen, Florian; Ertl-Wagner, Birgit; Alperin, Noam

2013-01-01

Purpose To compare venous drainage patterns and associated intracranial hydrodynamics between subjects who experienced mild traumatic brain injury (mTBI) and age- and gender-matched controls. Methods Thirty adult subjects (15 with mTBI and 15 age- and gender-matched controls) were investigated using a 3T MR scanner. Time since trauma was 0.5 to 29 years (mean 11.4 years). A 2D-time-of-flight MR-venography of the upper neck was performed to visualize the cervical venous vasculature. Cerebral venous drainage through primary and secondary channels, and intracranial compliance index and pressure were derived using cine-phase contrast imaging of the cerebral arterial inflow, venous outflow, and the craniospinal CSF flow. The intracranial compliance index is the defined as the ratio of maximal intracranial volume and pressure changes during the cardiac cycle. MR estimated ICP was then obtained through the inverse relationship between compliance and ICP. Results Compared to the controls, subjects with mTBI demonstrated a significantly smaller percentage of venous outflow through internal jugular veins (60.9±21% vs. controls: 76.8±10%; p = 0.01) compensated by an increased drainage through secondary veins (12.3±10.9% vs. 5.5±3.3%; p<0.03). Mean intracranial compliance index was significantly lower in the mTBI cohort (5.8±1.4 vs. controls 8.4±1.9; p<0.0007). Consequently, MR estimate of intracranial pressure was significantly higher in the mTBI cohort (12.5±2.9 mmHg vs. 8.8±2.0 mmHg; p<0.0007). Conclusions mTBI is associated with increased venous drainage through secondary pathways. This reflects higher outflow impedance, which may explain the finding of reduced intracranial compliance. These results suggest that hemodynamic and hydrodynamic changes following mTBI persist even in the absence of clinical symptoms and abnormal findings in conventional MR imaging. PMID:23405151

Contrast-enhanced ultrasound in portal venous system aneurysms: a multi-center study.

PubMed

Tana, Claudio; Dietrich, Christoph F; Badea, Radu; Chiorean, Liliana; Carrieri, Vincenzo; Schiavone, Cosima

2014-12-28

To investigate contrast-enhanced ultrasound (CEUS) findings in portal venous system aneurysms (PVSAs). In this multi-center, retrospective, case series study, we evaluated CEUS features of seven cases of PVSAs that were found incidentally on conventional ultrasound in the period 2007-2013. Three Ultrasound Centers were involved (Chieti, Italy, Bad Mergentheim, Germany, and Cluj-Napoca, Romania). All patients underwent CEUS with Sonovue(®) (Bracco, Milan, Italy) at a standard dose of 2.4 mL, followed by 10 mL of 0.9% saline solution. The examinations were performed using multifrequency transducers and low mechanical index. We considered aneurysmal a focal dilatation of the portal venous system with a size that was significantly greater than the remaining segments of the same vein, and that was equal or larger than 21 mm for the extrahepatic segments of portal venous system, main portal vein and bifurcation, and 9 mm for the intrahepatic branches. After contrast agent injection, all PVSAs were not enhanced in the arterial phase (starting 8-22 s). All PVSAs were then rapidly enhanced in the early portal venous phase (starting three to five seconds after the arterial phase, 11-30 s), with persistence and slow washout of the contrast agent in the late phase (starting 120 s). In all patients, CEUS confirmed the presence of a "to-and-fro" flow by showing a swirling pattern within the dilatation in the early portal venous phase. CEUS also improved the delineation of the lumen, and was reliable in showing its patency degree and integrity of walls. In one patient, CEUS showed a partial enhancement of the lumen with a uniformly nonenhancing area in the portal venous and late phases, suggesting thrombosis. In our case series, we found that CEUS could be useful in the assessment and follow-up of a PVSA. Further studies are needed to validate its diagnostic accuracy.

Patterning mechanisms of the sub-intestinal venous plexus in zebrafish

PubMed Central

Goi, Michela; Childs, Sarah J.

2017-01-01

Despite considerable interest in angiogenesis, organ-specific angiogenesis remains less well characterized. The vessels that absorb nutrients from the yolk and later provide blood supply to the developing digestive system are primarily venous in origin. In zebrafish, these are the vessels of the Sub-intestinal venous plexus (SIVP) and they represent a new candidate model to gain an insight into the mechanisms of venous angiogenesis. Unlike other vessel beds in zebrafish, the SIVP is not stereotypically patterned and lacks obvious sources of patterning information. However, by examining the area of vessel coverage, number of compartments, proliferation and migration speed we have identified common developmental steps in SIVP formation. We applied our analysis of SIVP development to obd mutants that have a mutation in the guidance receptor PlexinD1. obd mutants show dysregulation of nearly all parameters of SIVP formation. We show that the SIVP responds to a unique combination of pathways that control both arterial and venous growth in other systems. Blocking Shh, Notch and Pdgf signaling has no effect on SIVP growth. However Vegf promotes sprouting of the predominantly venous plexus and Bmp promotes outgrowth of the structure. We propose that the SIVP is a unique model to understand novel mechanisms utilized in organ-specific angiogenesis. PMID:26477558

Comparison of Two Devices for Intraoperative Portal Venous Flow Measurement in Living-Donor Liver Transplantation: Transit Time Ultrasound and Conventional Doppler Ultrasound.

PubMed

Wang, H-K; Chen, C-Y; Lin, N-C; Liu, C-S; Loong, C-C; Lin, Y-H; Lai, Y-C; Chiou, H-J

2018-05-01

Intraoperative portal venous flow measurement provides surgeons with instant guidance for portal flow modulation during living-donor liver transplantation (LDLT). In this study, we compared the agreement of portal flow measurement obtained by 2 devices: transit time ultrasound (TTU) and conventional Doppler ultrasound (CDU). Fifty-four recipients of LDLT underwent intraoperative measurement of portal flow after completion of vascular anastomosis of the implanted partial liver graft. Both TTU and CDU were used concurrently. Agreement of TTU and CDU was assessed by intraclass correlation coefficient using a model of 2-way random effects, absolute agreement, and single measurement. A Bland-Altman plot was applied to assess the variability between the 2 devices. The mean, median, and range of portal venous flow was 1456, 1418, and 117 to 2776 mL/min according to TTU; and 1564, 1566, and 119 to 3216 mL/min according to CDU. The intraclass correlation coefficient of portal venous flow between TTU and CDU was 0.68 (95% confidence interval, 0.51-0.80). The Bland-Altman plots revealed an average variation of 4.8% between TTU and CDU but with a rather wide 95% confidence interval of variation ranging from -57.7% to 67.4%. Intraoperative TTU and CDU showed moderate agreement in portal flow measurement. However, a relatively wide range of variation exists between TTU and CDU, indicating that data obtained from the 2 devices may not be interchangeable. Copyright © 2018 Elsevier Inc. All rights reserved.

Cannulation for veno-venous extracorporeal membrane oxygenation

PubMed Central

2018-01-01

Extracorporeal membrane oxygenation (ECMO) is described as a modified, smaller cardiopulmonary bypass circuit. The veno-venous (VV) ECMO circuit drains venous blood, oxygenate the blood, and pump the blood back into the same venous compartment. Draining and reinfusing in the same compartment means there are a risk of recirculation. The draining position within the venous system, ECMO pump flow, return flow position within the venous system and the patients cardiac output (CO) all have an impact on recirculation. Using two single lumen cannulas or one dual lumen cannula, but also the design of the venous cannula, can have an impact on where within the venous system the cannula is draining blood and will affect the efficiency of the ECMO circuit. VV ECMO can be performed with different cannulation strategies. The use of two single lumen cannulas draining in inferior vena cava (IVC) and reinfusing in superior vena cava (SVC) or draining in SVC and reinfusing in IVC, or one dual lumen cannula inserted in right jugular vein is all possible cannulation strategies. Independent of cannulation strategy there will be a risk of recirculation. Efficiency can be reasonable in either strategy if the cannulas are carefully positioned and monitored during the dynamic procedure of pulmonary disease. The disadvantage draining from IVC only occurs when there is a need for converting from VV to veno-arterial (VA) ECMO, reinfusing in the femoral artery. Then draining from SVC is the most efficient strategy, draining low saturated venous blood, and also means low risk of dual circulation. PMID:29732177

Impact of Tissue Factor Localization on Blood Clot Structure and Resistance under Venous Shear.

PubMed

Govindarajan, Vijay; Zhu, Shu; Li, Ruizhi; Lu, Yichen; Diamond, Scott L; Reifman, Jaques; Mitrophanov, Alexander Y

2018-02-27

The structure and growth of a blood clot depend on the localization of tissue factor (TF), which can trigger clotting during the hemostatic process or promote thrombosis when exposed to blood under pathological conditions. We sought to understand how the growth, structure, and mechanical properties of clots under flow are shaped by the simultaneously varying TF surface density and its exposure area. We used an eight-channel microfluidic device equipped with a 20- or 100-μm-long collagen surface patterned with lipidated TF of surface densities ∼0.1 and ∼2 molecules/μm 2 . Human whole blood was perfused at venous shear, and clot growth was continually measured. Using our recently developed computational model of clot formation, we performed simulations to gain insights into the clot's structure and its resistance to blood flow. An increase in TF exposure area resulted not only in accelerated bulk platelet, thrombin, and fibrin accumulation, but also in increased height of the platelet mass and increased clot resistance to flow. Moreover, increasing the TF surface density or exposure area enhanced platelet deposition by approximately twofold, and thrombin and fibrin generation by greater than threefold, thereby increasing both clot size and its viscous resistance. Finally, TF effects on blood flow occlusion were more pronounced for the longer thrombogenic surface than for the shorter one. Our results suggest that TF surface density and its exposure area can independently enhance both the clot's occlusivity and its resistance to blood flow. These findings provide, to our knowledge, new insights into how TF affects thrombus growth in time and space under flow. Copyright © 2018 Biophysical Society. All rights reserved.

The possibility for use of venous flaps in plastic surgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baytinger, V. F., E-mail: baitinger@mail.tomsknet.ru; Kurochkina, O. S., E-mail: kurochkinaos@yandex.ru; Selianinov, K. V.

2015-11-17

The use of venous flaps is controversial. The mechanism of perfusion of venous flaps is still not fully understood. The research was conducted on 56 white rats. In our experimental work we studied two different models of venous flaps: pedicled venous flap (PVF) and pedicled arterialized venous flap (PAVF). Our results showed that postoperative congestion was present in all flaps. However 66.7% of all pedicled venous flaps and 100% of all pedicled arterialized venous flaps eventually survived. Histological examination revealed that postoperatively the blood flow in the skin of the pedicled arterialized venous flap became «re-reversed» again; there were nomore » differences between mechanism of survival of venous flaps and other flaps. On the 7-14th day in the skin of all flaps were processes of neoangiogenesis and proliferation. Hence the best scenario for the clinical use of venous flaps unfolds when both revascularization and skin coverage are required.« less

Doppler echo evaluation of pulmonary venous-left atrial pressure gradients: human and numerical model studies

NASA Technical Reports Server (NTRS)

Firstenberg, M. S.; Greenberg, N. L.; Smedira, N. G.; Prior, D. L.; Scalia, G. M.; Thomas, J. D.; Garcia, M. J.

2000-01-01

The simplified Bernoulli equation relates fluid convective energy derived from flow velocities to a pressure gradient and is commonly used in clinical echocardiography to determine pressure differences across stenotic orifices. Its application to pulmonary venous flow has not been described in humans. Twelve patients undergoing cardiac surgery had simultaneous high-fidelity pulmonary venous and left atrial pressure measurements and pulmonary venous pulsed Doppler echocardiography performed. Convective gradients for the systolic (S), diastolic (D), and atrial reversal (AR) phases of pulmonary venous flow were determined using the simplified Bernoulli equation and correlated with measured actual pressure differences. A linear relationship was observed between the convective (y) and actual (x) pressure differences for the S (y = 0.23x + 0.0074, r = 0.82) and D (y = 0.22x + 0.092, r = 0.81) waves, but not for the AR wave (y = 0. 030x + 0.13, r = 0.10). Numerical modeling resulted in similar slopes for the S (y = 0.200x - 0.127, r = 0.97), D (y = 0.247x - 0. 354, r = 0.99), and AR (y = 0.087x - 0.083, r = 0.96) waves. Consistent with numerical modeling, the convective term strongly correlates with but significantly underestimates actual gradient because of large inertial forces.

Doppler echo evaluation of pulmonary venous-left atrial pressure gradients: human and numerical model studies.

PubMed

Firstenberg, M S; Greenberg, N L; Smedira, N G; Prior, D L; Scalia, G M; Thomas, J D; Garcia, M J

2000-08-01

The simplified Bernoulli equation relates fluid convective energy derived from flow velocities to a pressure gradient and is commonly used in clinical echocardiography to determine pressure differences across stenotic orifices. Its application to pulmonary venous flow has not been described in humans. Twelve patients undergoing cardiac surgery had simultaneous high-fidelity pulmonary venous and left atrial pressure measurements and pulmonary venous pulsed Doppler echocardiography performed. Convective gradients for the systolic (S), diastolic (D), and atrial reversal (AR) phases of pulmonary venous flow were determined using the simplified Bernoulli equation and correlated with measured actual pressure differences. A linear relationship was observed between the convective (y) and actual (x) pressure differences for the S (y = 0.23x + 0.0074, r = 0.82) and D (y = 0.22x + 0.092, r = 0.81) waves, but not for the AR wave (y = 0. 030x + 0.13, r = 0.10). Numerical modeling resulted in similar slopes for the S (y = 0.200x - 0.127, r = 0.97), D (y = 0.247x - 0. 354, r = 0.99), and AR (y = 0.087x - 0.083, r = 0.96) waves. Consistent with numerical modeling, the convective term strongly correlates with but significantly underestimates actual gradient because of large inertial forces.

The effect of a cryotherapy gel wrap on the microcirculation of skin affected by chronic venous disorders.

PubMed

Kelechi, Teresa J; Mueller, Martina; Zapka, Jane G; King, Dana E

2011-11-01

The aim of this randomized clinical trial was to investigate a cryotherapy (cooling) gel wrap applied to lower leg skin affected by chronic venous disorders to determine whether therapeutic cooling improves skin microcirculation. Chronic venous disorders are under-recognized vascular health problems that result in severe skin damage and ulcerations of the lower legs. Impaired skin microcirculation contributes to venous leg ulcer development, thus new prevention therapies should address the microcirculation to prevent venous leg ulcers. Sixty participants (n = 30 per group) were randomized to receive one of two daily 30-minute interventions for four weeks. The treatment group applied the cryotherapy gel wrap around the affected lower leg skin, or compression and elevated the legs on a special pillow each evening at bedtime. The standard care group wore compression and elevated the legs only. Laboratory pre- and post-measures included microcirculation measures of skin temperature with a thermistor, blood flow with a laser Doppler flowmeter, and venous refill time with a photoplethysmograph. Data were collected between 2008 2009 and analysed using descriptive statistics, paired t-tests or Wilcoxon signed ranks tests, logistic regression analyses, and mixed model analyses. Fifty-seven participants (treatment = 28; standard care = 29) completed the study. The mean age was 62 years, 70% female, 50% African American. In the final adjusted model, there was a statistically significant decrease in blood flow between the two groups (-6.2[-11.8; -0.6], P = 0.03). No statistically significant differences were noted in temperature or venous refill time. Study findings suggest that cryotherapy improves blood flow by slowing movement within the microcirculation and thus might potentially provide a therapeutic benefit to prevent leg ulcers. © 2011 Blackwell Publishing Ltd.

Human cerebral venous outflow pathway depends on posture and central venous pressure

PubMed Central

Gisolf, J; van Lieshout, J J; van Heusden, K; Pott, F; Stok, W J; Karemaker, J M

2004-01-01

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R2 = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins. PMID:15284348

Cardiovascular reflexes during rest and exercise modified by gravitational stresses

NASA Astrophysics Data System (ADS)

Bonde-petersen, Flemming

The hypotheses tested were whether variations in central venous pressure via the low pressure baroreceptors would take over or modify the arterial baroreceptor function, and further to which extent local and "whole body" hydrostatic stresses influence blood flow distribution. We investigated total forearm and skin blood flow (venous occlusion plethysmography and 133-Xe clearance) and cardiac output (rebreathing method) among other parameters. Hypo-and hypergravitational stresses were simulated by LBNP, LBPP, water immersion and lowering of the arm. The changes in flow distribution in the arm were ascribed to arterial baroreceptor function and not to low pressure baroreceptor activity. The enhancement of venous return during water immersion increased exercise tolerance during heat stress presumably due both to increased stroke volume and decreased venous pooling. The response to sustained handgrip exercise during LBNP and LBPP was not different from control measurements and the effects explained by arterial baroreceptor function. Application of exercise and local hydrostatic stresses in combination with gravitational stresses represent an interesting model for further study of the mechanisms behind the distribution of cardiac output to the peripheral organs.

Compression Therapy: Clinical and Experimental Evidence

PubMed Central

2012-01-01

Aim: A review is given on the different tools of compression therapy and their mode of action. Methods: Interface pressure and stiffness of compression devices, alone or in combination can be measured in vivo. Hemodynamic effects have been demonstrated by measuring venous volume and flow velocity using MRI, Duplex and radioisotopes, venous reflux and venous pumping function using plethysmography and phlebodynamometry. Oedema reduction can be measured by limb volumetry. Results: Compression stockings exerting a pressure of ~20 mmHg on the distal leg are able to increase venous blood flow velocity in the supine position and to prevent leg swelling after prolonged sitting and standing. In the upright position, an interface pressure of more than 50 mmHg is needed for intermittent occlusion of incompetent veins and for a reduction of ambulatory venous hypertension during walking. Such high intermittent interface pressure peaks exerting a “massaging effect” may rather be achieved by short stretch multilayer bandages than by elastic stockings. Conclusion: Compression is a cornerstone in the management of venous and lymphatic insufficiency. However, this treatment modality is still underestimated and deserves better understanding and improved educational programs, both for patients and medical staff. PMID:23641263

A randomized controlled trial of a mixed Kinesio taping-compression technique on venous symptoms, pain, peripheral venous flow, clinical severity and overall health status in postmenopausal women with chronic venous insufficiency.

PubMed

Aguilar-Ferrándiz, M Encarnación; Castro-Sánchez, Adelaida María; Matarán-Peñarrocha, Guillermo A; Guisado-Barrilao, Rafael; García-Ríos, M Carmen; Moreno-Lorenzo, Carmen

2014-01-01

To investigate the effect of a mixed Kinesio taping treatment in women with chronic venous insufficiency. A double-blinded randomized clinical trial. Clinical setting. One hundred and twenty postmenopausal women with mild-moderate chronic venous insufficiency were randomly assigned to an experimental group receiving standardized Kinesio taping treatment for gastrocnemius muscle enhancement and ankle functional correction, or to a placebo control group for simulated Kinesio taping. MAIN OUTCOMES VARIABLES: Venous symptoms, pain, photoplethysmographic measurements, bioelectrical impedance, temperature, severity and overall health were recorded at baseline and after four weeks of treatment. The 2 × 2 mixed model ANCOVA with repeated measurements showed statistically significant group * time interaction for heaviness (F = 22.99, p = 0.002), claudication (F = 8.57, p = 0.004), swelling (F = 22.58, p = 0.001), muscle cramps (F = 7.14, p = 0.008), venous refill time (right: F = 9.45, p = 0.023; left: F = 14.86, p = 0.001), venous pump function (right: F = 35.55, p = 0.004; left: F = 17.39 p = 0.001), extracellular water (right: F = 35.55, p = 0.004; left: F = 23.84, p = 0.001), severity (F = 18.47, p = 0.001), physical function (F = 9.15, p = 0.003) and body pain (F = 3.36, p = 0.043). Both groups reported significant reduction in pain. Mixed Kinesio taping-compression therapy improves symptoms, peripheral venous flow and severity and slightly increases overall health status in females with mild chronic venous insufficiency. Kinesio taping may have a placebo effect on pain.

A study to evaluate patterns of superficial venous reflux in patients with primary chronic venous disease.

PubMed

Qureshi, Mahim I; Gohel, Manj; Wing, Louise; MacDonald, Andrew; Lim, Chung S; Ellis, Mary; Franklin, Ian J; Davies, Alun H

2015-08-01

This study assessed patterns of superficial reflux in patients with primary chronic venous disease. Retrospective review of all patient venous duplex ultrasonography reports at one institution between 2000 and 2009. Legs with secondary, deep or no superficial reflux were excluded. In total, 8654 limbs were scanned; 2559 legs from 2053 patients (mean age 52.3 years) were included for analysis. Great saphenous vein reflux predominated (68%), followed by combined great saphenous vein/small saphenous vein reflux (20%) and small saphenous vein reflux (7%). The majority of legs with competent saphenofemoral junction had below-knee great saphenous vein reflux (53%); incompetent saphenofemoral junction was associated with combined above and below-knee great saphenous vein reflux (72%). Isolated small saphenous vein reflux was associated with saphenopopliteal junction incompetence (61%), although the majority of all small saphenous vein reflux limbs had a competent saphenopopliteal junction (57%). Superficial venous reflux does not necessarily originate from a saphenous junction. Large prospective studies with interval duplex ultrasonography are required to unravel the natural history of primary chronic venous disease. © The Author(s) 2014.

Selective inhibition by a synthetic hirudin peptide of fibrin-dependent thrombosis in baboons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadroy, Y.; Hanson, S.R.; Harker, L.A.

1991-02-15

To determine the importance of the thrombin substrate recognition exosite for fibrinogen binding in the formation of both arterial and venous thrombi the authors evaluated the antithrombotic effects of the tyrosine-sulfated dodecapeptide from residues 53-64 of hirudin (H peptide) in a nonhuman primate model. This peptide was studied because it inhibits thrombin cleavages of fibrinogen by simple competition without blocking enzyme catalytic-site function. When an exteriorized arteriovenous access shunt model was used in baboons (Papio anubis), thrombus formation was induced by placing a thrombogenic device made of (i) a segment of tubing coated covalently with type I collagen, which generatedmore » platelet-rich thrombi under arterial flow conditions, and (ii) two subsequent annular regions of flow expansion that produced fibrin-rich thrombi typically associated with venous valves and veins. Thrombus formation was quantified by measurements of {sup 111}In-labeled platelet and {sup 125}I-labeled fibrinogen deposition in both arterial-flow and venous-flow portions of the device. These finding suggest that, by competitive inhibition of fibrinogen binding to thrombin, fibrin-rich venous-type thrombus formation may be selectively prevented. This strategy may be therapeutically attractive for preserving normal platelet function when conventional anticoagulant therapy is contraindicated.« less

Venous Shunt Versus Venous Ligation for Vascular Damage Control: The Immunohistochemical Evidence.

PubMed

Góes Junior, Adenauer Marinho de Oliveira; Abib, Simone de Campos Vieira; Alves, Maria Teresa de Seixas; Ferreira, Paulo Sérgio Venerando da Silva; Andrade, Mariseth Carvalho de

2017-05-01

To evaluate the expression of immunohistochemical markers of tissue ischemia (iNOS, eNOS, and HSP70) in a vascular damage control experimental model to determine if a venous temporary vascular shunt insertion leads to a better limb perfusion when compared with the ligature of the injured vein. Experimental study in male Sus Scrofa weighting 40 Kg. Animals were distributed into 5 groups: group 1 animals were submitted to right external iliac artery (EIA) shunting and right external iliac vein (EIV) ligation; group 2 animals were submitted to right EIA shunting and right EIV shunting; group 3 animals were submitted to right EIV ligation; group 4 animals were submitted to right EIV shunting; group 5 animals were not submitted to vascular shunting or venous ligation. Transonic Systems flowmeters were used to measure vascular flow on right and left external iliac vessels, and i-STAT (Abbot) portable blood analyzer was used for EIVs blood biochemical analysis. An initial baseline register of invasive arterial pressure, iliac vessels flow, and venous blood analysis was performed. Arterial pressure and iliac vessels flow were taken immediately after right iliac vessels shunting or ligation. Then, hemorrhagic shock was induced by continuous 20 mL/min blood withdraw from the external right jugular vein whereas arterial blood pressure and iliac vessels flow registers were taken every 10 min, and blood samples from EIVs were obtained every 30 min until the vascular flow through right EIA (or through the shunt inserted into the right EIV for group 4 animals) became inexistent or until the animal's death. After the end of the experiments, bilateral hind limb's biopsies were obtained for immunohistochemical analysis. Using image editing and analysis software, the expression of iNOS, eNOS, and HSP70 (3 well-known ischemic associated immunohistochemical markers) was assessed. The mean expression of each marker in the right hind limb was compared between groups. For statistical analysis, Microsoft Office Excel 2007 and BioEstat 5.0 (2007) were used. Immunohistochemical analysis showed no difference regarding the iNOS expression; nevertheless, both eNOS and HSP70 expression were statistically more intense (P < 0.05) on group 1 (eNOS = 1.32; HSP70 = 15.05) than on group 2 (eNOS = 0.018; HSP70 = 8.56). The higher expression of eNOS and HSP70 in the right hind limbs of group 1 animals (arterial shunt and venous ligature) than group 2 animals (arterial shunt and venous shunt) suggests that venous ligation is associated with more intense ischemic histological findings than venous shunting. Copyright © 2017 Elsevier Inc. All rights reserved.

Management of Chronic Deep Vein Thrombosis in Women.

PubMed

Hardman, Rulon L

2018-03-01

Chronic deep vein thrombosis (DVT) affects hundreds of thousands of women in the United States. Chronic DVT can lead to pain, edema, venous ulcers, and varicosities. While there are limited data regarding the management of chronic DVT, several interventional radiology groups aggressively treat chronic DVT to aid patient symptom resolution. Recanalization of occluded veins and venous stenting re-establishes deep vein flow and decreases venous hypertension.

Cerebral ischemia and reperfusion increases the heterogeneity of local oxygen supply/consumption balance.

PubMed

Weiss, Harvey R; Grayson, Jeremy; Liu, Xia; Barsoum, Sylviana; Shah, Harsh; Chi, Oak Z

2013-09-01

After cerebral vessel blockage, local blood flow and O2 consumption becomes lower and oxygen extraction increases. With reperfusion, blood flow is partially restored. We examined the effects of ischemia-reperfusion on the heterogeneity of local venous oxygen saturation in rats in order to determine the pattern of microregional O2 supply/consumption balance in reperfusion. The middle cerebral artery was blocked for 1 hour using the internal carotid approach in 1 group (n=9) and was then reperfused for 2 hours in another group (n=9) of isoflurane-anesthetized rats. Regional cerebral blood flow was determined using a C(14)-iodoantipyrine autoradiographic technique. Regional small vessel arterial and venous oxygen saturations were determined microspectrophotometrically. After 1 hour of ischemia, local cerebral blood flow (92±10 versus 50±10 mL/min per 100 g) and O2 consumption (4.5±0.6 versus 2.7±0.5 mL O2/min per 100 g) decreased compared with the contralateral cortex. Oxygen extraction increased (4.7±0.2 versus 5.4±0.3 mL O2/100 mL) and the variation in small vein (20-60 μm) O2 saturation as determined by its coefficient of variation (=100×SD/mean) increased (5.5 versus 10.5). With 2 hours of reperfusion, the blood flow decrement was reduced and O2 consumption returned to the value in the contralateral cortex. Oxygen extraction remained elevated in the ischemic-reperfused area and the coefficient of variation of small vein O2 saturation increased further (17.3). These data indicated continued reduction of O2 supply/consumption balance with reperfusion. They also demonstrated many small regions of low oxygenation within the reperfused cortical region.

Effect of nordic walking and water aerobics training on body composition and the blood flow in lower extremities in elderly women.

PubMed

Jasiński, Ryszard; Socha, Małgorzata; Sitko, Ludmiła; Kubicka, Katarzyna; Woźniewski, Marek; Sobiech, Krzysztof A

2015-03-29

Nordic walking and water aerobics are very popular forms of physical activity in the elderly population. The aim of the study was to evaluate the influence of regular health training on the venous blood flow in lower extremities and body composition in women over 50 years old. Twenty-four women of mean age 57.9 (± 3.43) years, randomly divided into three groups (Nordic walking, water aerobics, and non-training), participated in the study. The training lasted 8 weeks, with one-hour sessions twice a week. Dietary habits were not changed. Before and after training vein refilling time and the function of the venous pump of the lower extremities were measured by photoplethysmography. Body composition was determined by bioelectrical impedance. Eight weeks of Nordic walking training improved the venous blood flow in lower extremities and normalized body composition in the direction of reducing chronic venous disorder risk factors. The average values of the refilling time variable (p = 0.04, p = 0.02, respectively) decreased in both the right and the left leg. After training a statistically significant increase in the venous pump function index was found only in the right leg (p = 0.04). A significant increase in fat-free mass, body cell mass and total body water was observed (p = 0.01), whereas body mass, the body mass index, and body fat decreased (p < 0.03). With regard to water aerobic training, no similar changes in the functions of the venous system or body composition were observed.

A novel approach to the management of critically ill neonatal Ebstein's anomaly: Veno-venous extracorporeal membrane oxygenation to promote right ventricular recovery.

PubMed

Bauser-Heaton, Holly; Nguyen, Charles; Tacy, Theresa; Axelrod, David

2015-01-01

This is the first report of the use of veno-venous extracorporeal membrane oxygenation in a neonate with severe Ebstein's anomaly. The report suggests the use of veno-venous extracorporeal membrane oxygenation in the immediate neonatal period may be a useful therapy in severe Ebstein's anomaly. By providing adequate oxygenation independent of the patient's native pulmonary blood flow, veno-venous extracorporeal membrane oxygenation allows the pulmonary vascular resistance to decrease and may promote right ventricular recovery.

Endothelial Notch signalling limits angiogenesis via control of artery formation

PubMed Central

Hasan, Sana S.; Tsaryk, Roman; Lange, Martin; Wisniewski, Laura; Moore, John C.; Lawson, Nathan D.; Wojciechowska, Karolina; Schnittler, Hans; Siekmann, Arndt F.

2017-01-01

Angiogenic sprouting needs to be tightly controlled. It has been suggested that the Notch ligand dll4 expressed in leading tip cells restricts angiogenesis by activating Notch signalling in trailing stalk cells. Here, we show using live imaging in zebrafish that activation of Notch signalling is rather required in tip cells. Notch activation initially triggers expression of the chemokine receptor cxcr4a. This allows for proper tip cell migration and connection to the pre-existing arterial circulation, ultimately establishing functional arterial-venous blood flow patterns. Subsequently, Notch signalling reduces cxcr4a expression, thereby preventing excessive blood vessel growth. Finally, we find that Notch signalling is dispensable for limiting blood vessel growth during venous plexus formation that does not generate arteries. Together, these findings link the role of Notch signalling in limiting angiogenesis to its role during artery formation and provide a framework for our understanding of the mechanisms underlying blood vessel network expansion and maturation. PMID:28714969

Appraising the plasticity of the circle of Willis: a model of hemodynamic modulation in cerebral arteriovenous malformations.

PubMed

Chuang, Yu-Ming; Guo, Wanyuo; Lin, Ching-Po

2010-01-01

Cerebral arteriovenous malformations (AVMs) harbor a network of abnormal vasculatures, namely the nidus between arterial and venous components. The pressure gradient between these two components results in abnormal high-velocity arteriovenous shunts flowing through the nidus and alternate intracranial hemodynamics. This study hypothesizes that the flow patterns of the circle of Willis (CoW) are modulated by the alternation of intracranial hemodynamics occurring in cerebral AVMs. The flow patterns of the CoW before and after AVMs had been corrected and the arteriovenous shunts closed by radiosurgery were assessed to validate the hypothesis. Fifty patients (32 men and 18 women; mean age 35.8 +/- 4.2, range 23-52 years) with cerebral AVMs previously treated by radiosurgery were retrospectively investigated. This investigation used magnetic resonance angiography, performed prior to and after AVM surgery, to assess the CoW flow patterns. The CoW flow patterns in nearly half of the subjects (20/50, 40%) altered after the AVMs had been corrected. The alterations included: (1) decreased size or ceased flow patterns in the CoW vascular segment: ipsilateral A1 (n = 1) of the anterior cerebral artery (ACA), ipsilateral posterior communicating artery (PCoA) segment (n = 7), contralateral PCoA collateral (n = 4), bilateral PCoA (n = 2); (2) increased size or opening of the previous 'hypoplastic' segment of CoW: ipsilateral A1 of ACA (n = 1), contralateral PCoA (n = 2), bilateral PCoA (n = 1), and (3) biphasic alteration of the CoW: ceased ipsilateral PCoA segment and opening ipsilateral A1 of the ACA (n = 1), ceased ipsilateral PCoA and opening contralateral P1 of the posterior cerebral artery (n = 1). The plasticity of the flow patterns in the CoW are modulated by intracranial hemodynamics as shown by the AVM model. The calibers of CoW arterial segments are not a static feature. Willisian collateralization with recruitment of the CoW segment may cease, or hypoplastic segments may reopen after closing arteriovenous shunts of the AVM. (c) 2010 S. Karger AG, Basel.

In vitro validation of a self-driving aortic-turbine venous-assist device for Fontan patients.

PubMed

Pekkan, Kerem; Aka, Ibrahim Basar; Tutsak, Ece; Ermek, Erhan; Balim, Haldun; Lazoglu, Ismail; Turkoz, Riza

2018-03-11

Palliative repair of single ventricle defects involve a series of open-heart surgeries where a single-ventricle (Fontan) circulation is established. As the patient ages, this paradoxical circulation gradually fails, because of its high venous pressure levels. Reversal of the Fontan paradox requires an extra subpulmonic energy that can be provided through mechanical assist devices. The objective of this study was to evaluate the hemodynamic performance of a totally implantable integrated aortic-turbine venous-assist (iATVA) system, which does not need an external drive power and maintains low venous pressure chronically, for the Fontan circulation. Blade designs of the co-rotating turbine and pump impellers were developed and 3 prototypes were manufactured. After verifying the single-ventricle physiology at a pulsatile in vitro circuit, the hemodynamic performance of the iATVA system was measured for pediatric and adult physiology, varying the aortic steal percentage and circuit configurations. The iATVA system was also tested at clinical off-design scenarios. The prototype iATVA devices operate at approximately 800 revolutions per minute and extract up to 10% systemic blood from the aorta to use this hydrodynamic energy to drive a blood turbine, which in turn drives a mixed-flow venous pump passively. By transferring part of the available energy from the single-ventricle outlet to the venous side, the iATVA system is able to generate up to approximately 5 mm Hg venous recovery while supplying the entire caval flow. Our experiments show that a totally implantable iATVA system is feasible, which will eliminate the need for external power for Fontan mechanical venous assist and combat gradual postoperative venous remodeling and Fontan failure. Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Clinical Investigation Program (Tripler Army Medical Center)

DTIC Science & Technology

1991-10-01

temperatures - arterial and central venous blood pressure, relevant blood and urinary hormones, and urine flows will be measured via indwelling catheters...Analysis of central venous pressure recordings are not yet complete, but all experimentation is complete. 21 Detail Summary Sheet Prot No: llA91 Status... catheterized newborn rats are performed. Rats are instrumented with arterial, venous , and stomach catheters and a bladder cannula 3 to 7 days before

Daily nursing care on patients undergoing venous-venous extracorporeal membrane oxygenation: a challenging procedure!

PubMed

Redaelli, Sara; Zanella, Alberto; Milan, Manuela; Isgrò, Stefano; Lucchini, Alberto; Pesenti, Antonio; Patroniti, Nicolò

2016-12-01

Daily nursing in critical care patients may alter vital parameters, especially in the most critically ill patients. The aim of our study was to evaluate feasibility and safety of daily nursing on patients undergoing venous-venous extracorporeal membrane oxygenation (vv-ECMO) for severe respiratory failure. Daily nursing was performed following defined phases (sponge bath, elevation with scooping stretcher, change position of endotracheal tube, dressing replacement). We recorded physiological and ECMO parameters before and during daily nursing in 5 patients for several days (total: 25 daily nursing) and adverse events: desaturation, hypertension, reduction of mixed venous oxygen saturation, arterial oxygen saturation or ECMO blood flow and elevation in minute ventilation. Sedative drug dosage and additional bolus were recorded. Daily nursing was performed in 92 % of cases (23/25), with a minimum of two adverse events per daily nursing. Hypertension and tachycardia were mostly recorded at the beginning, while desaturation, reduction in mixed venous oxygen saturation and blood flow were recorded during elevation with scooping stretcher. Increase in minute ventilation was frequent in spontaneous breathing patients. Additional bolus of sedation was required before and/or during nursing. Daily nursing significantly alters physiologic parameters; thus, it should be performed only when physicians are readily available to treat adverse events.

Age differences in arterial and venous extra-cerebral blood flow in healthy adults: contributions of vascular risk factors and genetic variants.

PubMed

Raz, Naftali; Daugherty, Ana M; Sethi, Sean K; Arshad, Muzamil; Haacke, E Mark

2017-08-01

Sufficient cerebral blood flow (CBF) and venous drainage are critical for normal brain function, and their alterations can affect brain aging. However, to date, most studies focused on arterial CBF (inflow) with little attention paid to the age differences in venous outflow. We measured extra-cerebral arterial and venous blood flow rates with phase-contrast MRI and assessed the influence of vascular risk factors and genetic polymorphisms (ACE insertion/deletion, COMT val158met, and APOEε4) in 73 adults (age 18-74 years). Advanced age, elevated vascular risk, ACE Deletion, and COMT met alleles were linked to lower in- and outflow, with no effects of APOE ε4 noted. Lower age-related CBF rate was unrelated to brain volume and was observed only in val homozygotes of COMTval158met. Thus, in a disease-free population, age differences in CBF may be notable only in persons with high vascular risk and carriers of genetic variants associated with vasoconstriction and lower dopamine availability. It remains to be established if treatments targeting alleviation of the mutable factors can improve the course of cerebrovascular aging in spite of the immutable genetic influence.

Measurements Of Coronary Mean Transit Time And Myocardial Tissue Blood Flow By Deconvolution Of Intravasal Tracer Dilution Curves

NASA Astrophysics Data System (ADS)

Korb, H.; Hoeft, A.; Hellige, G.

1984-10-01

Previous studies have shown that intramyocardial blood volume does not vary to a major extent even during extreme variation of hemodynamics and coronary vascular tone. Based on a constant intramyocardial blood volume it is therefore possible to calculate tissue blood flow from the mean transit time of an intravascular tracer. The purpose of this study was to develop a clinically applicable method for measurement of coronary blood flow. The new method was based on indocyanine green, a dye which is bound to albumin and intravasally detectable by means of a fiberoptic catheter device. One fiberoptic catheter was placed in the aortic root and another in the coronary sinus. After central venous dye injection the resulting arterial and coronary venous dye dilution curves were processed on-line by a micro-computer. The mean transit time as well as myocardial blood flow were calculated from the step response function of the deconvoluted arterial and coronary venous signals. Reference flow was determined with an extracorporeal electromagnetic flowprobe within a coronary sinus bypass system. 38 steady states with coronary blood flow ranging from 49 - 333 ml/min*100g were analysed in 5 dogs. Mean transit times varied from 2.9 to 16.6 sec. An average intracoronary blood volume of 13.9 -7 1.8 m1/100g was calculated. The correlation between flow determined by the dye dilution technique and flow measured with the reference method was 0.98. According to these results determination of coronary blood flow with a double fiberoptic system and indocyanine green should be possible even under clinical conditions. Furthermore, the arterial and coronary venous oxygen saturation can be monitored continuously by the fiberoptic catheters. Therefore, additional information about the performance of the heart such as myocardial oxygen consumption and myocardial efficiency is available with the same equipment.

Mathematical modelling of a human external respiratory system

NASA Technical Reports Server (NTRS)

1977-01-01

A closed system of algebraic and common differential equations solved by computer is investigated. It includes equations which describe the activity pattern of the respiratory center, the phrenic nerve, the thrust produced by the diaphragm as a function of the lung volume and discharge frequency of the phrenic nerve, as well as certain relations of the lung stretch receptors and chemoreceptors on various lung and blood characteristics, equations for lung biomechanics, pulmonary blood flow, alveolar gas exchange and capillary blood composition equations to determine various air and blood flow and gas exchange parameters, and various gas mixing and arterial and venous blood composition equations, to determine other blood, air and gas mixing characteristics. Data are presented by means of graphs and tables, and some advantages of this model over others are demonstrated by test results.

Is there a link between the structural impact of thoracic outlet and the development of central venous stenosis?

PubMed

Kotoda, Atsushi; Akimoto, Tetsu; Sugase, Taro; Yamamoto, Hisashi; Kusano, Eiji

2013-01-01

Central venous stenosis (CVS) is a serious complication for chronic hemodialysis (HD) patients. Previous reports of CVS have focused on prior central venous catheterization, because of the higher prevalence and potential for prevention of such an event. However, recent studies have demonstrated that CVS may also develop without a history of central venous catheterization. Although information about the etiological backgrounds regarding the development of CVS without previous central venous catheterization have gradually accumulated, the clinical impact of the chronic compression of the central venous system by the surrounding structures, which may likely determine the central venous susceptibility to CVS, remains poorly understood. This study proposes the hypothesis that the combination of chronic venous compression at the level of thoracic outlet characterized by the natural physique and elevated venous flow induced by the creation of vascular access should be evaluated as a potential factor for the development of CVS, since they may accelerate the development of venous stenosis, presumably through the stimulation of intimal hyperplasia, and thereby the subclavian venous susceptibility to CVS should be determined. Copyright © 2012 Elsevier Ltd. All rights reserved.

Acute vascular effects of waterpipe smoking: Importance of physical activity and fitness status.

PubMed

Alomari, Mahmoud A; Khabour, Omar F; Alzoubi, Karem H; Shqair, Dana M; Stoner, Lee

2015-06-01

While new forms of tobacco, including waterpipe (WP) smoking, continue to gain popularity, limited literature has examined the vascular health consequences. The purpose of the current study was to examine: (i) the acute WP-induced changes in vascular function; (ii) whether acute changes in vascular function are modified by lifestyle behaviors (habitual physical activity, physical fitness). Fifty three (22.7 y, 36% F, 23.4 kg/m(2)) otherwise healthy WP smokers were recruited. Strain-gauge plethysmography was used to measure forearm blood flow, vascular resistance, venous capacitance, and venous outflow at rest and following occlusion. Habitual physical activity was determined using the Arabic version of short-form international physical activity questionnaire, while physical fitness was assessed using the 6 min walk test and handgrip strength. Partial correlations were used to examine the relationships between post-smoking vascular function and lifestyle behaviors, controlling for pre-smoking vascular measures. (i) WP had a small effect on forearm post-occlusion blood flow (d = -0.19), a moderate effect on venous outflow (d = 0.30), and a moderate effect on post-occlusion vascular resistance (d = 0.32). (ii) Total habitual physical activity strongly correlated with resting blood flow (r = 0.50) and moderately with vascular resistance (r = -0.40). Handgrip strength moderately correlated with venous capacitance (r = 0.30) and post-occlusion blood flow (r = 0.30), while 6 min walked distance moderately correlated with resting venous capacitance (r = 0.30). Waterpipe smoking is associated with immediate changes in vascular function, which are exacerbated in individuals with low habitual physical activity and physical fitness levels in young otherwise healthy individuals. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The echocardiographic diagnosis of totally anomalous pulmonary venous connection in the fetus.

PubMed

Allan, L D; Sharland, G K

2001-04-01

Infants with isolated totally anomalous pulmonary venous return often present severely decompensated, such that they are at high risk for surgical repair. On the other hand, if surgical repair can be safely accomplished, the outlook is usually good. Thus prenatal diagnosis would be expected to improve the prognosis for the affected child. To describe the features of isolated totally anomalous pulmonary venous drainage in the fetus. Four fetuses with isolated totally anomalous pulmonary venous connection were identified and the echocardiographic images reviewed. Measurements of the atrial and ventricular chambers and both great arteries were made and compared with normal values. Referral centre for fetal echocardiography. There were two cases of drainage to the coronary sinus, one to the right superior vena cava, and one to the inferior vena cava. Right heart dilatation relative to left heart structures was a feature of two cases early on, and became evident in some ratios late in pregnancy in the remaining two. Ventricular and great arterial disproportion in the fetus can indicate a diagnosis of totally anomalous pulmonary venous connection above the diaphragm. However, in the presence of an atrial septal defect or with infradiaphragmatic drainage, right heart dilatation may not occur until late in pregnancy. The diagnosis of totally anomalous pulmonary venous drainage in fetal life can only be reliably excluded by direct examination of pulmonary venous blood flow entering the left atrium on colour or pulsed flow mapping.

Plasmapheresis affects responses of slowly and rapidly adapting airway receptors to pulmonary venous congestion in dogs.

PubMed Central

Kappagoda, C T; Ravi, K

1989-01-01

1. The effects of plasmapheresis on the responses of rapidly adapting receptors (RARs) and slowly adapting receptors (SARs) of the airways to pulmonary venous congestion were examined in dogs anaesthetized with alpha-chloralose. Pulmonary venous congestion was produced in a graded manner by partial obstruction of the mitral valve sufficient to raise the mean left atrial pressure by 5, 10 and 15 mmHg. Plasmapheresis was performed by withdrawing 10% of blood volume twice. 2. Both RARs (n = 11) and SARs (n = 5) responded to pulmonary venous congestion by increasing their activities. The responses of the former were proportionately greater. 3. After plasmapheresis which reduced the concentration of plasma proteins by 12.3 +/- 1.0%, the responses of the RARs to pulmonary venous congestion were enhanced significantly. There was no significant change in the responses of SARs. 4. In another set of six RARs, the effects of graded pulmonary venous congestion were investigated twice with an interval of 45 min between the two observations. No significant differences were noted between the two responses. 5. Collection of lymph from the tracheobronchial lymph duct (n = 6) showed that after plasmapheresis, there was an increase in the control lymph flow. In addition, the lymph flow was enhanced during pulmonary venous congestion (mean left atrial pressure increased by 10 mmHg). 6. It is suggested that a natural stimulus for the excitation of the RAR is a function of the fluid fluxes in the pulmonary extravascular space. PMID:2607464

The effect of a cryotherapy gel wrap on the microcirculation of skin affected by Chronic Venous Disorders

PubMed Central

Mueller, Martina; Zapka, Jane G.; King, Dana E.

2011-01-01

Aim This randomized clinical trial was conducted 2008 – 2009 to investigate a cryotherapy (cooling) gel wrap applied to lower leg skin affected by chronic venous disorders to determine whether therapeutic cooling improves skin microcirculation. Impaired skin microcirculation contributes to venous leg ulcer development, thus new prevention therapies should address the microcirculation to prevent venous leg ulcers. Data Sources Sixty participants (n = 30 per group) were randomized to receive one of two daily 30-minute interventions for four weeks. The treatment group applied the cryotherapy gel wrap around the affected lower leg skin, or compression and elevated the legs on a special pillow each evening at bedtime. The standard care group wore compression and elevated the legs only. Laboratory pre- and post-measures included microcirculation measures of skin temperature with a thermistor, blood flow with a laser Doppler flowmeter, and venous refill time with a photoplethysmograph. Review methods Data were analysed using descriptive statistics, paired t-tests or Wilcoxon signed ranks tests, logistic regression analyses, and mixed model analyses. Results Fifty-seven participants (treatment = 28; standard care = 29) completed the study. The mean age was 62 years, 70% female, 50% African American. In the final adjusted model, there was a statistically significant decrease in blood flow between the two groups (−6.2[−11.8; −0.6], P = 0.03). No statistically significant differences were noted in temperature or venous refill time. Conclusion Study findings suggest that cryotherapy improves blood flow by slowing movement within the microcirculation and thus might potentially provide a therapeutic benefit to prevent leg ulcers. PMID:21592186

Combined Recirculatory-compartmental Population Pharmacokinetic Modeling of Arterial and Venous Plasma S(+) and R(-) Ketamine Concentrations.

PubMed

Henthorn, Thomas K; Avram, Michael J; Dahan, Albert; Gustafsson, Lars L; Persson, Jan; Krejcie, Tom C; Olofsen, Erik

2018-05-16

The pharmacokinetics of infused drugs have been modeled without regard for recirculatory or mixing kinetics. We used a unique ketamine dataset with simultaneous arterial and venous blood sampling, during and after separate S(+) and R(-) ketamine infusions, to develop a simplified recirculatory model of arterial and venous plasma drug concentrations. S(+) or R(-) ketamine was infused over 30 min on two occasions to 10 healthy male volunteers. Frequent, simultaneous arterial and forearm venous blood samples were obtained for up to 11 h. A multicompartmental pharmacokinetic model with front-end arterial mixing and venous blood components was developed using nonlinear mixed effects analyses. A three-compartment base pharmacokinetic model with additional arterial mixing and arm venous compartments and with shared S(+)/R(-) distribution kinetics proved superior to standard compartmental modeling approaches. Total pharmacokinetic flow was estimated to be 7.59 ± 0.36 l/min (mean ± standard error of the estimate), and S(+) and R(-) elimination clearances were 1.23 ± 0.04 and 1.06 ± 0.03 l/min, respectively. The arm-tissue link rate constant was 0.18 ± 0.01 min and the fraction of arm blood flow estimated to exchange with arm tissue was 0.04 ± 0.01. Arterial drug concentrations measured during drug infusion have two kinetically distinct components: partially or lung-mixed drug and fully mixed-recirculated drug. Front-end kinetics suggest the partially mixed concentration is proportional to the ratio of infusion rate and total pharmacokinetic flow. This simplified modeling approach could lead to more generalizable models for target-controlled infusions and improved methods for analyzing pharmacokinetic-pharmacodynamic data.

48-hours administration of fenoterol in spontaneous preterm labor - Doppler blood flow assessment of placental and fetal circulation.

PubMed

Grzesiak, Mariusz; Hincz, Piotr; Forys, Sebastian; Ahmed, Rehana B; Wilczynski, Jan

2013-01-01

The aims were to investigate whether any changes in placental and fetal circulation were observed during fenoterol tocolysis within the first 48 hours of therapy. Doppler evaluation of placental and fetal circulation was performed prior to fenoterol administration and then after 24 and 48 hours. Maternal heart rate and pulsatility index (PI) in uterine arteries were assessed. FHR, RI and PI of umbilical artery and middle cerebral artery were measured. E/A ratio for A-V valves, the myocardial performance index (MPI) and shortening fraction (SF) were calculated for both ventricles independently. The blood flow pattern in DV was assessed using PI, S/a ratio and peak velocity index for the vein. To determine changes over time in all study variable analysis of variance (ANOVA) for repeated measurements followed by Tukey-Kramer's multiple comparison test was used. The effects of additional clinical covariates were checked. Uterine and fetal arterial blood flow patterns were not altered significantly during 48 hours of tocolysis. No significant changes were observed in fetal cardiac function parameters as well. The evaluation of Doppler parameters in the DV revealed a significant increase in PVIV after 48 hours. Additionally after 48 hours of successful tocolysis S/a ratio values were significantly lower. Short term intravenous administration of fenoterol seems not to alter uterine and fetal arterial blood flow pattern. Direct fetal cardiac function remained unaffected. However significant changes of selected Doppler parameters in DV may suggest further studies should be performed to assess more precisely fetal venous blood flow.

Effective use of flow-spoiled FBI and time-SLIP methods in the diagnostic study of an aberrant vessel of the head and neck: "left jugular venous steal by the right jugular vein".

PubMed

Kogure, Taroh; Kogure, Kyuya; Iizuka, Mitsumasa; Ino, Azusa; Ishii, Masako

2010-08-01

Three-dimensional (3D) time-of-flight (TOF) is now commonly used in routine magnetic resonance angiography (MRA) studies of the head and neck. However, there are limits to its diagnostic abilities in the clinical field and, in some instances, a more invasive supplementary examination may be required. We incidentally discovered a patient with an aberrant vessel of the head and neck that ran alongside the left carotid artery and contained a constant, slowly pulsating efferent blood flow. 3D-TOF and carotid ultrasonography could not determine the nature and origin of this vessel. Additional studies using flow-spoiled fresh blood imaging (flow-spoiled FBI) and time spatial labeling inversion pulse (time-SLIP) methods were effective in determining that the vessel was the left jugular vein, and that the continuous venous reflux was a result of a venous steal by the right jugular vein. We show that by combining different MRA techniques we can effectively achieve diagnosis without resorting to more invasive examinations. 2010 Wiley-Liss, Inc.

Temporal gradients in shear stimulate osteoblastic proliferation via ERK1/2 and retinoblastoma protein

NASA Technical Reports Server (NTRS)

Jiang, Guang-Liang; White, Charles R.; Stevens, Hazel Y.; Frangos, John A.

2002-01-01

Bone cells are subject to interstitial fluid flow (IFF) driven by venous pressure and mechanical loading. Rapid dynamic changes in mechanical loading cause transient gradients in IFF. The effects of pulsatile flow (temporal gradients in fluid shear) on rat UMR106 cells and rat primary osteoblastic cells were studied. Pulsatile flow induced a 95% increase in S-phase UMR106 cells compared with static controls. In contrast, ramped steady flow stimulated only a 3% increase. Similar patterns of S-phase induction were also observed in rat primary osteoblastic cells. Pulsatile flow significantly increased relative UMR106 cell number by 37 and 62% at 1.5 and 24 h, respectively. Pulsatile flow also significantly increased extracellular signal-regulated kinase (ERK1/2) phosphorylation by 418%, whereas ramped steady flow reduced ERK1/2 activation to 17% of control. Correspondingly, retinoblastoma protein was significantly phosphorylated by pulsatile fluid flow. Inhibition of mitogen-activated protein (MAP)/ERK kinase (MEK)1/2 by U0126 (a specific MEK1/2 inhibitor) reduced shear-induced ERK1/2 phosphorylation and cell proliferation. These findings suggest that temporal gradients in fluid shear stress are potent stimuli of bone cell proliferation.

A NATO Guide for Assessing Deployability for Military Personnel with Medical Conditions (Guide OTAN d’evaluation de l’aptitude medicale a la projection du personnel militaire)

DTIC Science & Technology

2014-06-01

Pulmonary Embolism (PE) / Deep Venous Thrombosis (DVT) 3-9 3.2.16.3 Venous Insufficiency 3-9 3.2.17 Vision/Ophthalmology 3-9 3.2.17.1 Refractive Surgery...Thoracic Aortic Aneurysms 3-63 3.3.16.2 History of Pulmonary Embolism (PE) or Deep Venous Thrombosis 3-65 (DVT) 3.3.16.3 Venous Insufficiency 3-67...Drugs OCD Obsessive-Compulsive Disorder PASI Psoriasis Area and Severity Index PE Pulmonary Embolism PEF Peak Expiratory Flow PHA Periodic

Venous saturation and blood flow behavior during laser-induced photodissociation of oxyhemoglobin

NASA Astrophysics Data System (ADS)

Mamilov, S. A.; Yesman, S. S.; Asimov, M. M.; Gisbrecht, A. I.

2013-03-01

The value of relative oxyhemoglobin concentration (saturation) in arterial (SаO2) and venous blood (SvO2) plays a significant role in the oxygen exchange in tissue and is used as criterion of delivery of oxygen adequate to the needs of tissue cells. Reduction of the volume of blood flows as well as reduction of oxygen concentration in arterial blood causes hypoxia - deficit of oxygen in tissue. One of the main mechanisms of elimination of hypoxia is based on compensation of the oxygen deficit by increasing the oxygen extraction from arterial blood, which leads to reduction of oxygen in the venous blood 1. In this report two optical techniques for measurement of venous blood saturation are presented. The first one is based on the pulseoximetry with artificial mechanical modulation of the tissue volume and the second one on the spectrophotometry of human respiratory rhythm. Good correlation between the results obtained with both techniques is observed.

Transvenous Embolization of a Spontaneous Femoral AVF 5 Years After an Incomplete Treatment with Arterial Stent-Grafts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peynircioglu, Bora; Ozkan, Murat; Dogan, Omer Faruk

2008-03-15

A 66-year-old man with complex left femoral arterio-venous fistula (AVF) was first diagnosed after a deep venous thrombosis incident approximately 5 years ago. Partial treatment was performed by means of endografts along the superficial femoral artery, which remained patent for 5 years. The patient had been doing well until a couple of months ago when he developed severe venous stasis and ulcers of the left cruris, due to a high-flow nonhealing complex AVF with additional iliac vein occlusion. Therefore; the definitive treatment was performed by a unique endovascular technique combined with surgical venous bypass (femoro-femoral crossover saphenous bypass, the Palmamore » operation). A novel percutaneous transvenous technique for occlusion of a complex high-flow AVF is reported with a review of the literature. The case is unique with spontaneous AVF, transvenous embolization with detachable coils and ONYX, and the hybrid treatment technique as well as the long-term patency of superficial femoral artery stent-grafts.« less

[Venous access in oncology].

PubMed

Lesimple, T; Béguec, J F; Levêque, J M

1998-10-31

Many treatments administered to cancer patients require venous access either via a peripheral vein or a larger central vein at the risk of local or systemic infection, thrombus formation or venous occlusion and dysfunction. Insertion of a central catheter is an invasive procedure which must be conducted under conditions of rigorous asepsia. Strict rules based on well-defined protocols must be applied throughout its use. Local or systemic infectious complications account for 18 to 25% of all nosocomial infections and are often related to colonisation of the puncture site by a Gram positive germ. In case of infection, ablation of the central catheter is not mandatory for diagnosis or antibiotic treatment. Reported at varying frequencies in the literature from 4 to 42%, thrombus formation is unpredictable and often difficult to diagnose. Anticoagulants or fibrolytic agents are indicated but it may also be necessary to withdraw the catheter. Displacement, rupture, obstruction and extravasation are frequent complications. Back flow must be checked in all venous accesses and free flow carefully verified. The access must remain patent throughout the period of use, guaranteed by a standard heparinization and rinsing protocol. This complications must not mask the important progress achieved with the use of central venous access for specific and symptomatic treatment in cancer patients.

[Effects of lidocaine on arterial and venous circulation of limbs in man].

PubMed

Edouard, A; Probst, D; Duranteau, J; Tarot, J P; Pussard, E

1991-01-01

The effects of intravenous lidocaine on limb arteries and veins were investigated in a placebo-controlled study. Seven young healthy volunteers, 23 to 28-years-old, were included. Electrocardiogram, arterial pressure and arm and leg blood flows were recorded continuously. Systolic and diastolic blood pressures were measured in the left arm by finger photoplethysmography. Limb blood flow and the limb venous system were studied by venous occlusive plethysmography. The venous parameters studied were venous tone, lowest closing pressure, venous volume at 30 mmHg, and venous distensibility. After an initial bolus of 1.5 mg.kg-1 lidocaine had been given, 30, and then 60, micrograms.kg-1.min-1 were given for one hour each. Plasma noradrenaline and serum lidocaine titres were measured before giving the lidocaine, and at the end of each one hour period. Placebo consisted in a two hour infusion of 0.25 ml.min-1 normal saline. Lidocaine titres were 1.64 +/- 0.40 microgram.ml-1 after one hour, and 2.55 +/- 0.69 microgram.ml-1 after two hours. Lidocaine increased vascular resistances in both the forearm (+81% to +93%) and the calf (+38% to +57%). There was a concomitant increase in mean arterial blood pressure (+21% to +28%) without any change in heart rate. There was a significant dose-dependent increase in plasma noradrenaline levels during the second period of the lidocaine infusion with respect to the preinfusion period and the same period during the placebo infusion. Venous capacitance measured before any infusion had been started was greater in the leg than in the arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Penile blood flow by xenon-133 washout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haden, H.T.; Katz, P.G.; Mulligan, T.

1989-06-01

Penile erectile failure is often attributed to abnormalities of vascular supply or drainage, but few direct measurements of penile blood flow have been made. We describe the xenon washout method for measurement of penile blood flow, and present the results obtained in a group of normal and impotent subjects. The procedure was performed with standard nuclear imaging equipment. Flaccid-state penile blood flow in the impotent patients studied was not significantly different from the normal group, suggesting that flaccid-state measurements may not be helpful in evaluation of erectile failure. However, this method can be used to measure penile venous outflow withmore » stimulated or induced erection, and may provide a method for detecting abnormal venous leakage.« less

[Venous and arteriovenous malformations in the head and neck region. Therapeutic options and challenges].

PubMed

Eivazi, B; Werner, J A

2014-01-01

Venous malformations are the prototype low-flow malformations in the head and neck region. Arteriovenous malformations (AVM) represent the main high-flow malformations. In recent years it has been possible to significantly optimize the therapeutic options for venous malformations. In addition to conventional surgery, laser treatment and sclerotherapy have become established techniques and the importance of embolization with new alcohol-based materials is increasing. AVM are progressive and destructive diseases. Therapy of choice is usually a combined treatment comprising embolization and surgical removal of the arteriovenous nidus. This curative approach is usually possible if diagnosis is made at an early stage. Incomplete embolization or sole ligation of the arterial supply causes progression. There is a clear need for improved therapeutic methods and pharmacotherapeutic approaches.

Electrical stimulation of acupoint combinations against deep venous thrombosis in elderly bedridden patients after major surgery.

PubMed

Hou, Lili; Chen, Cuiping; Xu, Lei; Yin, Peihao; Peng, Wen

2013-04-01

To compare the effects of electrical stimulation of different acupoint combinations among postoperative bedridden elderly patients on hemorheology and deep venous blood flow velocity and investigate the.role of electrical stimulation against deep vein thrombosis (DVT). From November 2010 to October 2011, a total of 160 elderly bedridden patients after major surgery were divided into the conventional care group, invigorating and promoting Qi group, blood-activating and damp-eliminating group, and acupoint-combination stimulation group. Whole blood viscosity, plasma viscosity, D-dimer levels, lower limb skin temperature, lower limb circumference, and flow velocities of the external iliac vein, femoral vein, popliteal vein, and deep calf veins in all patients were documented and compared among the four groups. Whole blood viscosity, plasma viscosity, D-dimer levels, and lower limb circumference were significantly reduced in the blood-activating and damp-eliminating group compared with the conventional care group (P < 0.05) and were almost equal to those in the acupoint-combination stimulation group (P > 0.05). Lower limb venous flow velocities were accelerated in the invigorating and promoting Qi group compared with the other groups, excluding the acupoint-combination stimulation group (P < 0.05). Hemorheological indices in postoperative bedridden elderly patients were improved after combined electrical stimulation at Yinlingquan (SP 9) and Sanyinjiao (SP 6). Combined electrical stimulation at Zusanli (ST 36) and Taichong (LR 3), on the other hand, accelerated lower limb venous flow.

Stasis Dermatitis: Pathophysiology, Evaluation, and Management.

PubMed

Sundaresan, Swaminathan; Migden, Michael R; Silapunt, Sirunya

2017-06-01

Stasis dermatitis commonly occurs in older age. It is caused by venous hypertension resulting from retrograde flow due to incompetent venous valves, valve destruction, or obstruction of the venous system. Further tissue changes arise from an inflammatory process mediated by metalloproteinases, which are up-regulated by ferric ion from extravasated red blood cells. Stasis dermatitis presents initially as poorly demarcated erythematous plaques of the lower legs bilaterally, classically involving the medial malleolus. It is one of the spectrum of cutaneous findings that may result from chronic venous insufficiency. Its mimics include cellulitis, contact dermatitis, and pigmented purpuric dermatoses. Duplex ultrasound is useful in demonstrating venous reflux when the clinical diagnosis of stasis dermatitis is inadequate. Conservative treatment involves the use of compression therapy directed at improving ambulatory venous pressure. Interventional therapy currently includes minimally invasive techniques such as endovenous thermal ablation and ultrasound-guided foam sclerotherapy, which have supplanted the use of open surgical techniques.

Gas6 Promotes Inflammatory (CCR2hiCX3CR1lo) Monocyte Recruitment in Venous Thrombosis.

PubMed

Laurance, Sandrine; Bertin, François-René; Ebrahimian, Talin; Kassim, Yusra; Rys, Ryan N; Lehoux, Stéphanie; Lemarié, Catherine A; Blostein, Mark D

2017-07-01

Coagulation and inflammation are inter-related. Gas6 (growth arrest-specific 6) promotes venous thrombosis and participates to inflammation through endothelial-innate immune cell interactions. Innate immune cells can provide the initiating stimulus for venous thrombus development. We hypothesize that Gas6 promotes monocyte recruitment during venous thrombosis. Deep venous thrombosis was induced in wild-type and Gas6-deficient (-/-) mice using 5% FeCl 3 and flow reduction in the inferior vena cava. Total monocyte depletion was achieved by injection of clodronate before deep venous thrombosis. Inflammatory monocytes were depleted using an anti-C-C chemokine receptor type 2 (CCR2) antibody. Similarly, injection of an anti-chemokine ligand 2 (CCL2) antibody induced CCL2 depletion. Flow cytometry and immunofluorescence were used to characterize the monocytes recruited to the thrombus. In vivo, absence of Gas6 was associated with a reduction of monocyte recruitment in both deep venous thrombosis models. Global monocyte depletion by clodronate leads to smaller thrombi in wild-type mice. Compared with wild type, the thrombi from Gas6 -/- mice contain less inflammatory (CCR2 hi CX 3 CR1 lo ) monocytes, consistent with a Gas6-dependent recruitment of this monocyte subset. Correspondingly, selective depletion of CCR2 hi CX 3 CR1 lo monocytes reduced the formation of venous thrombi in wild-type mice demonstrating a predominant role of the inflammatory monocytes in thrombosis. In vitro, the expression of both CCR2 and CCL2 were Gas6 dependent in monocytes and endothelial cells, respectively, impacting monocyte migration. Moreover, Gas6-dependent CCL2 expression and monocyte migration were mediated via JNK (c-Jun N-terminal kinase). This study demonstrates that Gas6 specifically promotes the recruitment of inflammatory CCR2 hi CX 3 CR1 lo monocytes through the regulation of both CCR2 and CCL2 during deep venous thrombosis. © 2017 American Heart Association, Inc.

Successful transcatheter closure of a congenital high-flow portosystemic venous shunt with the Amplatzer vascular plug II.

PubMed

Guneyli, Serkan; Cinar, Celal; Bozkaya, Halil; Parildar, Mustafa; Oran, Ismail; Akin, Yigit

2012-12-01

Congenital portosystemic venous shunt is extremely rare and should be treated. Advances in treatment techniques allow for patients to be treated safely. We present a 9-year-old boy with a large congenital portosystemic venous shunt. The shunt was occluded interventionally with the Amplatzer vascular plug II. Our case was unique with its clinical manifestation, the use of a 22-mm Amplatzer vascular plug II, and the presence of the patient's 1-year follow-up.

Vascular Patterns in Iguanas and Other Squamates: Blood Vessels and Sites of Thermal Exchange

PubMed Central

Porter, William Ruger; Witmer, Lawrence M.

2015-01-01

Squamates use the circulatory system to regulate body and head temperatures during both heating and cooling. The flexibility of this system, which possibly exceeds that of endotherms, offers a number of physiological mechanisms to gain or retain heat (e.g., increase peripheral blood flow and heart rate, cooling the head to prolong basking time for the body) as well as to shed heat (modulate peripheral blood flow, expose sites of thermal exchange). Squamates also have the ability to establish and maintain the same head-to-body temperature differential that birds, crocodilians, and mammals demonstrate, but without a discrete rete or other vascular physiological device. Squamates offer important anatomical and phylogenetic evidence for the inference of the blood vessels of dinosaurs and other extinct archosaurs in that they shed light on the basal diapsid condition. Given this basal positioning, squamates likewise inform and constrain the range of physiological thermoregulatory mechanisms that may have been found in Dinosauria. Unfortunately, the literature on squamate vascular anatomy is limited. Cephalic vascular anatomy of green iguanas (Iguana iguana) was investigated using a differential-contrast, dual-vascular injection (DCDVI) technique and high-resolution X-ray microcomputed tomography (μCT). Blood vessels were digitally segmented to create a surface representation of vascular pathways. Known sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in brain and cephalic thermoregulation. Blood vessels to and from sites of thermal exchange were investigated to detect conserved vascular patterns and to assess their ability to deliver cooled blood to the dural venous sinuses. Arteries within sites of thermal exchange were found to deliver blood directly and through collateral pathways. The venous drainage was found to have multiple pathways that could influence neurosensory tissue temperature, as well as pathways that would bypass neurosensory tissues. The orbital region houses a large venous sinus that receives cooled blood from the nasal region. Blood vessels from the nasal region and orbital sinus show anastomotic connections to the dural sinus system, allowing for the direct modulation of brain temperatures. The generality of the vascular patterns discovered in iguanas were assessed by firsthand comparison with other squamates taxa (e.g., via dissection and osteological study) as well as the literature. Similar to extant archosaurs, iguanas and other squamates have highly vascularized sites of thermal exchange that likely support physiological thermoregulation that “fine tunes” temperatures attained through behavioral thermoregulation. PMID:26466378

Vascular Patterns in Iguanas and Other Squamates: Blood Vessels and Sites of Thermal Exchange.

PubMed

Porter, William Ruger; Witmer, Lawrence M

2015-01-01

Squamates use the circulatory system to regulate body and head temperatures during both heating and cooling. The flexibility of this system, which possibly exceeds that of endotherms, offers a number of physiological mechanisms to gain or retain heat (e.g., increase peripheral blood flow and heart rate, cooling the head to prolong basking time for the body) as well as to shed heat (modulate peripheral blood flow, expose sites of thermal exchange). Squamates also have the ability to establish and maintain the same head-to-body temperature differential that birds, crocodilians, and mammals demonstrate, but without a discrete rete or other vascular physiological device. Squamates offer important anatomical and phylogenetic evidence for the inference of the blood vessels of dinosaurs and other extinct archosaurs in that they shed light on the basal diapsid condition. Given this basal positioning, squamates likewise inform and constrain the range of physiological thermoregulatory mechanisms that may have been found in Dinosauria. Unfortunately, the literature on squamate vascular anatomy is limited. Cephalic vascular anatomy of green iguanas (Iguana iguana) was investigated using a differential-contrast, dual-vascular injection (DCDVI) technique and high-resolution X-ray microcomputed tomography (μCT). Blood vessels were digitally segmented to create a surface representation of vascular pathways. Known sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in brain and cephalic thermoregulation. Blood vessels to and from sites of thermal exchange were investigated to detect conserved vascular patterns and to assess their ability to deliver cooled blood to the dural venous sinuses. Arteries within sites of thermal exchange were found to deliver blood directly and through collateral pathways. The venous drainage was found to have multiple pathways that could influence neurosensory tissue temperature, as well as pathways that would bypass neurosensory tissues. The orbital region houses a large venous sinus that receives cooled blood from the nasal region. Blood vessels from the nasal region and orbital sinus show anastomotic connections to the dural sinus system, allowing for the direct modulation of brain temperatures. The generality of the vascular patterns discovered in iguanas were assessed by firsthand comparison with other squamates taxa (e.g., via dissection and osteological study) as well as the literature. Similar to extant archosaurs, iguanas and other squamates have highly vascularized sites of thermal exchange that likely support physiological thermoregulation that "fine tunes" temperatures attained through behavioral thermoregulation.

Quantum dot interactions and flow effects in angiogenic zebrafish (Danio rerio) vessels and human endothelial cells.

PubMed

Jiang, Xiao-Yu; Sarsons, Christopher D; Gomez-Garcia, M Juliana; Cramb, David T; Rinker, Kristina D; Childs, Sarah J

2017-04-01

Nanoparticle (NP) interactions with biological tissues are affected by the size, shape and surface chemistry of the NPs. Here we use in vivo (zebrafish) and in vitro (HUVEC) models to investigate association of quantum dots (QDs) with endothelial cells and the effect of fluid flow. After injection into the developing zebrafish, circulating QDs associate with endothelium and penetrate surrounding tissue parenchyma over time. Amino-functionalized QDs cluster, interact with cells, and clear more rapidly than carboxy-functionalized QDs in vivo, highlighting charge influences. QDs show stronger accumulation in slow-flowing, small caliber venous vessels than in fast-flowing high caliber arterial vessels. Parallel-plate flow experiments with HUVEC support these findings, showing reduced QD-EC association with increasing flow. In vivo, flow arrest after nanoparticle injection still results in venous accumulation at 18 h. Overall our results suggest that both QD charge and blood flow modulate particle-endothelial cell interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

Renal and femoral venous blood flows are regulated by different mechanisms dependent on α-adrenergic receptor subtypes and nitric oxide in anesthetized rats.

PubMed

Fioretti, Alexandre C; Ogihara, Cristiana A; Cafarchio, Eduardo M; Venancio, Daniel P; de Almeida, Roberto Lopes; Antonio, Bruno B; Sato, Monica A

2017-12-01

Venous and arterial walls are responsive to sympathetic system and circulating substances, nevertheless, very few is known about the venous blood flow regulation simultaneously to arterial vascular beds. In this study, we compared the venous and arterial blood flow regulation in visceral and muscular beds upon injection of different doses of vasoactive drugs which act in arterial vascular beds. Anesthetized adult male Wistar rats underwent to right femoral artery and vein cannulation for hemodynamic recordings and infusion of drugs. Doppler flow probes were placed around the left renal artery and vein, and left femoral artery and vein to evaluate the changes in flood flow. Phenylephrine (PHE) injection (α 1 -adrenergic receptor agonist) elicited vasoconstriction in all arteries and veins. Intravenous prazosin (PZS) (1mg/kg, α 1 -adrenergic receptor blocker) caused renal artery vasodilation, but not in the other beds. Vasoconstrictor effect of PHE was abolished by PZS in all vascular beds, except in femoral vein. Phentolamine (PTL) injection (1mg/kg, α 1 /α 2 -adrenergic receptor blocker) produced renal artery vasodilation with no change in other beds. After PTL, the vasoconstriction evoked by PHE was abolished in all vascular beds. Sodium Nitroprusside (SNP), a nitric oxide donor, elicited vasodilation in all beds, and after PTL but not post PZS injection, SNP enhanced the vasodilatory effect in femoral vein. Our findings suggest that the vasoconstriction in renal and femoral veins is mediated by different subtypes of α-adrenoceptors. The nitric oxide-dependent vasodilation in femoral vein enhances when α 2 -adrenoceptors are not under stimulation, but not in the other vascular beds investigated. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrical foot stimulation and implications for the prevention of venous thromboembolic disease.

PubMed

Kaplan, Robert E; Czyrny, James J; Fung, Tat S; Unsworth, John D; Hirsh, Jack

2002-08-01

Venous stasis caused by immobility is an important risk factor for deep vein thrombosis following surgery and lower limb trauma, in bed-ridden medical patients, and in high-risk long distance air travelers. A safe and convenient method for reducing venous stasis would be useful in patients while in hospital and after discharge during their rehabilitation. 49 healthy subjects aged 51-76 were seated for 4 hours during which they received mild electrical stimulation of the calf, or sole of the foot (plantar muscles). Popliteal and femoral venous blood flow velocities were measured via doppler ultrasound. The non-stimulated lower extremity served as the simultaneous control. Subjects completed a questionnaire regarding their acceptance and tolerance of the electrical stimulation. There was a significant increase in venous femoral and popliteal blood flow for both calf (p < 0.035, p < 0.003), and plantar muscles (p < 0.0001, p < 0.009) on the stimulated side compared to the unstimulated side. The magnitude of the effect was similar for calf and plantar muscle stimulation. Subjects did not find the experience uncomfortable, and would use an electrical stimulator if told by their physician that they were at risk for developing blood clots. Mild electrical stimulation of the feet, as well as the calf, is a safe effective and convenient method for counteracting venous stasis and therefore has the potential to reduce the risk of deep vein thrombosis and pulmonary embolism for subjects who are immobilized.

N-acetylcysteine induces shedding of selectins from liver and intestine during orthotopic liver transplantation

PubMed Central

Taut, F J H; Schmidt, H; Zapletal, C M; Thies, J C; Grube, C; Motsch, J; Klar, E; Martin, E

2001-01-01

In orthotopic liver transplantation (OLT), N-acetylcysteine (NAC) reduces ischaemia/reperfusion (I/R) injury, improves liver synthesis function and prevents primary nonfunction of the graft. To further elucidate the mechanisms of these beneficial effects of NAC, we investigated influence of high-dose NAC therapy on the pattern of adhesion molecule release from liver and intestine during OLT. Nine patients receiving allograft OLT were treated with 150 mg NAC/kg during the first hour after reperfusion; 10 patients received the carrier only. One hour after reperfusion, samples of arterial, portal venous and hepatic venous plasma were taken and blood flow in the hepatic artery and the portal vein was measured. Absolute concentrations of sICAM-1, sVCAM-1, sP-selectin and sE-selectin were not markedly different. However, balance calculations showed release of selectins from NAC-treated livers as opposed to net uptake in controls (P ≤ 0·02 for sP-selectin). This shedding of selectins might be a contributing factor to the decrease in leucocyte adherence and improved haemodynamics found experimentally with NAC-treatment. PMID:11422213

Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow.

PubMed

Nakatani, S; Garcia, M J; Firstenberg, M S; Rodriguez, L; Grimm, R A; Greenberg, N L; McCarthy, P M; Vandervoort, P M; Thomas, J D

1999-09-01

The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography. Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)). Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results. In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94. A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.

Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow

NASA Technical Reports Server (NTRS)

Nakatani, S.; Garcia, M. J.; Firstenberg, M. S.; Rodriguez, L.; Grimm, R. A.; Greenberg, N. L.; McCarthy, P. M.; Vandervoort, P. M.; Thomas, J. D.

1999-01-01

OBJECTIVES: The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography. BACKGROUND: Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)). METHODS: Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results. RESULTS: In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94. CONCLUSIONS: A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.

Effect of PEEP, blood volume, and inspiratory hold maneuvers on venous return.

PubMed

Berger, David; Moller, Per W; Weber, Alberto; Bloch, Andreas; Bloechlinger, Stefan; Haenggi, Matthias; Sondergaard, Soren; Jakob, Stephan M; Magder, Sheldon; Takala, Jukka

2016-09-01

According to Guyton's model of circulation, mean systemic filling pressure (MSFP), right atrial pressure (RAP), and resistance to venous return (RVR) determine venous return. MSFP has been estimated from inspiratory hold-induced changes in RAP and blood flow. We studied the effect of positive end-expiratory pressure (PEEP) and blood volume on venous return and MSFP in pigs. MSFP was measured by balloon occlusion of the right atrium (MSFPRAO), and the MSFP obtained via extrapolation of pressure-flow relationships with airway occlusion (MSFPinsp_hold) was extrapolated from RAP/pulmonary artery flow (QPA) relationships during inspiratory holds at PEEP 5 and 10 cmH2O, after bleeding, and in hypervolemia. MSFPRAO increased with PEEP [PEEP 5, 12.9 (SD 2.5) mmHg; PEEP 10, 14.0 (SD 2.6) mmHg, P = 0.002] without change in QPA [2.75 (SD 0.43) vs. 2.56 (SD 0.45) l/min, P = 0.094]. MSFPRAO decreased after bleeding and increased in hypervolemia [10.8 (SD 2.2) and 16.4 (SD 3.0) mmHg, respectively, P < 0.001], with parallel changes in QPA Neither PEEP nor volume state altered RVR (P = 0.489). MSFPinsp_hold overestimated MSFPRAO [16.5 (SD 5.8) vs. 13.6 (SD 3.2) mmHg, P = 0.001; mean difference 3.0 (SD 5.1) mmHg]. Inspiratory holds shifted the RAP/QPA relationship rightward in euvolemia because inferior vena cava flow (QIVC) recovered early after an inspiratory hold nadir. The QIVC nadir was lowest after bleeding [36% (SD 24%) of preinspiratory hold at 15 cmH2O inspiratory pressure], and the QIVC recovery was most complete at the lowest inspiratory pressures independent of volume state [range from 80% (SD 7%) after bleeding to 103% (SD 8%) at PEEP 10 cmH2O of QIVC before inspiratory hold]. The QIVC recovery thus defends venous return, possibly via hepatosplanchnic vascular waterfall. Copyright © 2016 the American Physiological Society.

The Influence of a Pfannenstiel Scar on Venous Anatomy of the Lower Abdominal Wall and Implications for Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction.

PubMed

Kim, So Young; Lee, Kyeong-Tae; Mun, Goo-Hyun

2017-03-01

A Pfannenstiel incision involves the obstruction of superficial venous pathways and functional diversion of flow through alternative pathways and adjacent vessels. This study investigated the effect of a prior Pfannenstiel incision on venous anatomy of the lower abdominal wall; specifically, the superficial inferior epigastric vein (SIEV), using computed tomographic angiography. A case-control study was performed of 50 patients with Pfannenstiel scars and 50 age-matched, body mass index-matched control patients without Pfannenstiel scars. The authors compared the number of direct/indirect and total communications between the SIEV and deep inferior epigastric artery perforator (DIEP) venae comitantes, midline crossover, and other SIEV-related anatomical changes by using computed tomographic angiography. Flap-related clinical outcomes and donor-site-related complications were also assessed. The median number of direct and total communications between the SIEV and DIEP venae comitantes in the study group was greater than in the control group. The percentage of SIEVs having more than two branching patterns per hemiabdomen was significantly higher in the study group than in the control group. The study group also showed a significantly lower rate of fat necrosis compared with the control group (p = 0.03). The rate of donor-site seroma was significantly higher in the study group. This study suggests that the presence of a Pfannenstiel scar may promote the development of direct and total communications between the SIEV and DIEP venae comitantes and branching within the SIEV in the lower abdominal wall, which may facilitate venous drainage of adipose tissue in DIEP flap breast reconstruction. Risk, II.

The side-to-side fashion for individual distal coronary anastomosis using venous conduit.

PubMed

Kato, Takayoshi; Tsunekawa, Tomohiro; Motoji, Yusuke; Hirakawa, Akihiro; Okawa, Yasuhide; Tomita, Shinji

2017-04-01

Regarding to coronary artery bypass grafting (CABG), the end-to-side anastomosis (ESA) has been performed as a gold standard. Recently, the effectiveness of the distal side-to-side anastomosis (SSA) in CABG using internal mammary artery has been reported. The benefit of SSA comparing to ESA also has been disclosed by computing simulation. However, use of SSA by venous conduit for individual CABG has not been reported. In this study, we investigated feasibility of SSA. From January 2013 to October 2014, we conducted 114 CABGs. There were 92 venous distal anastomoses without sequential anastomotic site (61 SSA and 31 ESA). The anastomosis was evaluated before discharge and at 1 year after the procedure by angiography or multi-detector row computed tomographic coronary angiography. The median values for time to anastomosis were 13 min in the two group (p = 0.89). There was no revision of anastomosis in both groups. Additional stitches for hemostasis were required significantly less in SSA than ESA (18.0 vs 45.2 %, respectively, p < 0.05). Early angiographic patency; 96.6 % for SSA vs 93.5 % for ESA (p = 0.50), and percentage of good anastomotic figure; 91.2 % for SSA vs 87.1 % for ESA (p = 0.54) were similar in both groups. The angiographic patency at 1 year were 92.9 % for SSA and 81.0 % for ESA (p = 0.16). There was no predictive factor for early and late graft failure. Our study showed feasibility of SSA using venous conduit in individual CABG based on early and mid-term angiographic results. This anastomotic fashion is easy to perform and maybe beneficial in blood flow pattern.

Intimal Hyperplasia, Stenosis, and Arteriovenous Fistula Maturation Failure in the Hemodialysis Fistula Maturation Study.

PubMed

Cheung, Alfred K; Imrey, Peter B; Alpers, Charles E; Robbin, Michelle L; Radeva, Milena; Larive, Brett; Shiu, Yan-Ting; Allon, Michael; Dember, Laura M; Greene, Tom; Himmelfarb, Jonathan; Roy-Chaudhury, Prabir; Terry, Christi M; Vazquez, Miguel A; Kusek, John W; Feldman, Harold I

2017-10-01

Intimal hyperplasia and stenosis are often cited as causes of arteriovenous fistula maturation failure, but definitive evidence is lacking. We examined the associations among preexisting venous intimal hyperplasia, fistula venous stenosis after creation, and clinical maturation failure. The Hemodialysis Fistula Maturation Study prospectively observed 602 men and women through arteriovenous fistula creation surgery and their postoperative course. A segment of the vein used to create the fistula was collected intraoperatively for histomorphometric examination. On ultrasounds performed 1 day and 2 and 6 weeks after fistula creation, we assessed fistula venous stenosis using pre-specified criteria on the basis of ratios of luminal diameters and peak blood flow velocities at certain locations along the vessel. We determined fistula clinical maturation using criteria for usability during dialysis. Preexisting venous intimal hyperplasia, expressed per 10% increase in a hyperplasia index (range of 0%-100%), modestly associated with lower fistula blood flow rate (relative change, -2.5%; 95% confidence interval [95% CI], -4.6% to -0.4%; P =0.02) at 6 weeks but did not significantly associate with stenosis (odds ratio [OR], 1.07; 95% CI, 1.00 to 1.16; P =0.07) at 6 weeks or failure to mature clinically without procedural assistance (OR, 1.07; 95% CI, 0.99 to 1.15; P =0.07). Fistula venous stenosis at 6 weeks associated with maturation failure (OR, 1.98; 95% CI, 1.25 to 3.12; P =0.004) after controlling for case mix factors, dialysis status, and fistula location. These findings suggest that postoperative fistula venous stenosis associates with fistula maturation failure. Preoperative venous hyperplasia may associate with maturation failure but if so, only modestly. Copyright © 2017 by the American Society of Nephrology.

Effect of sequential pneumatic compression therapy on venous blood velocity, refilling time, pain and quality of life in women with varicose veins: a randomized control study

PubMed Central

Yamany, Abeer; Hamdy, Bassant

2016-01-01

[Purpose] The aim of this study was to investigate the effects of sequential pneumatic compression therapy on venous blood flow, refilling time, pain level, and quality of life in women with varicose veins. [Subjects and Methods] Twenty-eight females with varicose veins were selected and randomly allocated to a control group, and experimental group. Maximum and mean venous blood velocities, the refilling time, pain by visual analog scale and quality of life by Aberdeen Varicose Veins Questionnaire were measured in all patients before and after six weeks of treatment. Both groups received lower extremity exercises; in addition, patients in the experimental group received sequential pneumatic compression therapy for 30 minutes daily, five days a week for six weeks. [Results] All measured parameters improved significantly in both groups, comparison of post treatment measurements between groups showed that the maximum and mean blood flow velocity, the pain level, and quality of life were significantly higher in the experimental group compared with the control group. On the other hand there was no significant difference between groups for refilling time. [Conclusion] Sequential pneumatic compression therapy with the applied parameters was an effective modality for increasing venous blood flow, reducing pain, and improving quality of women life with varicose veins. PMID:27512247

Hemodynamic effects of spiral ePTFE prosthesis compared with standard arteriovenous graft in a carotid to jugular vein porcine model.

PubMed

Jahrome, Ommid K; Hoefer, Imo; Houston, Graeme J; Stonebridge, Peter A; Blankestijn, Peter J; Moll, Frans L; de Borst, Gert J

2011-01-01

The primary patency rate of arteriovenous (AV) grafts is limited by distal venous anastomosis stenosis or occlusion due to intimal hyperplasia associated with distal graft turbulence. The normal blood flow in native arteries is spiral laminar flow. Standard vascular grafts do not produce spiral laminar flow at the distal anastomosis. Vascular grafts which induce a spiral laminar flow distally result in lower turbulence, particularly near the vessel wall. This initial study compares the hemodynamic effects of a spiral flow-inducing graft and a standard graft in a new AV carotid to jugular vein crossover graft porcine model. Four spiral flow grafts and 4 control grafts were implanted from the carotid artery to the contralateral jugular vein in 4 pigs. Two animals were terminated after 48 hours and 2 at 14 days. Graft patency was assessed by selective catheter digital angiography, and the flow pattern was assessed by intraoperative flow probe and color Doppler ultrasound (CDU) measurements. The spiral grafts were also assessed at enhanced flow rates using an external roller pump to simulate increased flow rates that may occur during dialysis using a standard dialysis needle cannulation. The method increased the flow rate through the graft by 660 ml/min. The graft distal anastomotic appearances were evaluated by explant histopathology. All grafts were patent at explantation with no complications. All anastomoses were found to be wide open and showed no significant angiographic stenosis at the distal anastomosis in both spiral and control grafts. CDU examinations showed a spiral flow pattern in the spiral graft and double helix pattern in the control graft. No gross histopathological effects were seen in either spiral or control grafts. This porcine model is robust and allows hemodynamic flow assessment up to 14 days postimplantation. The spiral flow-inducing grafts produced and maintained spiral flow at baseline and enhanced flow rates during dialysis needle cannulation, whereas control grafts did not produce spiral flow through the distal anastomosis. There was no deleterious effect of the spiral flow-inducing graft on macroscopic and histological examination. The reducing effect of spiral flow on intima hyperplasia formation will be the subject of further study using the same AV graft model at a longer period of implantation.

Contribution of Circulatory Disturbances in Subchondral Bone to the Pathophysiology of Osteoarthritis.

PubMed

Aaron, Roy K; Racine, Jennifer; Dyke, Jonathan P

2017-08-01

This review describes the contributions of abnormal bone circulation to the pathophysiology of osteoarthritis. Combining dynamic imaging with MRI and PET with previous observations reveals that venous stasis and a venous outlet syndrome is most likely the key circulatory pathology associated with the initiation or progression of osteoarthritis. MRI and PET have revealed that venous outflow obstruction results in physicochemical changes in subchondral bone to which osteoblasts are responsive. The osteoblasts express an altered pattern of cytokines, many of which can serve as structural or signaling molecules contributing to both bone remodeling and cartilage degeneration. The patterns of circulatory changes are associated with alterations in the physicochemical environment of subchondral bone, including hypoxia. Osteoblast cytokines can transit the subchondral bone plate and calcified cartilage and communicate with chondrocytes.

Prediction of venous wound healing with laser speckle imaging.

PubMed

van Vuuren, Timme Maj; Van Zandvoort, Carina; Doganci, Suat; Zwiers, Ineke; tenCate-Hoek, Arina J; Kurstjens, Ralph Lm; Wittens, Cees Ha

2017-12-01

Introduction Laser speckle imaging is used for noninvasive assessment of blood flow of cutaneous wounds. The aim of this study was to assess if laser speckle imaging can be used as a predictor of venous ulcer healing. Methods After generating the flux speckle images, three regions of interest (ROI) were identified to measure the flow. Sensitivity, specificity, negative predictive value, and positive predictive value for ulcer healing were calculated. Results In total, 17 limbs were included. A sensitivity of 92.3%, specificity of 75.0%, PPV of 80.0%, and NPV 75.0% were found in predicting wound healing based on laser speckle images. Mean flux values were lowest in the center (ROI I) and showed an increase at the wound edge (ROI II, p = 0.03). Conclusion Laser speckle imaging shows acceptable sensitivity and specificity rates in predicting venous ulcer healing. The wound edge proved to be the best probability for the prediction of wound healing.

Potential involvement of the extracranial venous system in central nervous system disorders and aging

PubMed Central

2013-01-01

Background The role of the extracranial venous system in the pathology of central nervous system (CNS) disorders and aging is largely unknown. It is acknowledged that the development of the venous system is subject to many variations and that these variations do not necessarily represent pathological findings. The idea has been changing with regards to the extracranial venous system. Discussion A range of extracranial venous abnormalities have recently been reported, which could be classified as structural/morphological, hemodynamic/functional and those determined only by the composite criteria and use of multimodal imaging. The presence of these abnormalities usually disrupts normal blood flow and is associated with the development of prominent collateral circulation. The etiology of these abnormalities may be related to embryologic developmental arrest, aging or other comorbidities. Several CNS disorders have been linked to the presence and severity of jugular venous reflux. Another composite criteria-based vascular condition named chronic cerebrospinal venous insufficiency (CCSVI) was recently introduced. CCSVI is characterized by abnormalities of the main extracranial cerebrospinal venous outflow routes that may interfere with normal venous outflow. Summary Additional research is needed to better define the role of the extracranial venous system in relation to CNS disorders and aging. The use of endovascular treatment for the correction of these extracranial venous abnormalities should be discouraged, until potential benefit is demonstrated in properly-designed, blinded, randomized and controlled clinical trials. Please see related editorial: http://www.biomedcentral.com/1741-7015/11/259. PMID:24344742

Partial anomalous pulmonary venous drainage. A novel approach to repair.

PubMed

Hanhan, U A; Moodie, D S; Gill, C C; Sterba, R; Currie, P; Stewart, R

1989-01-01

Isolated partial anomalous pulmonary venous drainage with an intact atrial septum is a rare finding. The authors describe their experience with three patients (ages 9, 37, and 54 years), with partial anomalous pulmonary venous connection to the superior vena cava, right atrium, and inferior vena cava, who underwent extracardiac conduit repair of this anomaly. In all three patients, a synthetic Gortex graft was used for reconstruction of the venous pathways to the left atrium. The follow-up period ranged from 10 to 82 months (mean, 42 months). All three patients were evaluated with intravenous digital angiography, transesophageal echocardiography, or both at 10, 33, and 82 months postoperatively. Patency of the grafts with no evidence of obstruction and excellent pulmonary venous flow was shown. This surgical technique is an excellent option for correction of this anomaly, and intravenous digital subtraction angiography is a useful diagnostic tool during the postoperative period to evaluate patency of the repair.

Analysis of the dynamics of venous blood flow in the context of lower limb temperature distribution and tissue composition in the elderly.

PubMed

Skomudek, Aleksandra; Gilowska, Iwona; Jasiński, Ryszard; Rożek-Piechura, Krystyna

2017-01-01

The elderly are particularly vulnerable to degenerative diseases, such as circulatory and respiratory system and vascular system diseases. The objective of this study was therefore to evaluate the distribution of temperature and the dynamics of venous blood flow in the lower limbs (LLs) and to assess the interdependence of these parameters in terms of the somatic components in males and females participating in activities at the University of the Third Age. The study included 60 females (mean age 67.4 years) and 40 males (mean age 67.5 years). A body composition assessment was performed using the bioimpedance technique - Tanita BC-418MA. The following parameters were examined: fat%, fat mass, fat-free mass, and total body water. The minimal, maximal, and mean temperature values and their distributions were examined using infrared thermographic camera VarioCAM Head. Measurements of the venous refilling time and the work of the LL venous pump were examined using a Rheo Dopplex II PPG. In males, the mean value of the right LL temperature was 30.58 and the mean value of the left LL was 30.28; the P -value was 0.805769. In females, the mean value of the right LL temperature was 29.58 and the mean value of the left limb was 29.52; the P -value was 0.864773. In males, the right limb blood flow was 34.17 and the left limb blood flow was 34.67; the P -value was 0.359137. In females, the right limb blood flow was 26.89 and the left limb blood flow was 26.09; the P -value was 0.796348. Research results showed that the temperature distribution and the dynamics of blood flow are not significantly different between the right and left extremities in both males and females. However, significant temperature differences were found between the gender groups. Significantly higher temperature values in both the right and left extremities were recorded in males than in females.

Cost-effectiveness of wound management in France: pressure ulcers and venous leg ulcers.

PubMed

Meaume, S; Gemmen, E

2002-06-01

This study set out to define realistic protocols of care for the treatment of chronic venous leg ulcers and pressure ulcers in France and, by developing cost-effectiveness models, to compare the different protocols of care for the two ulcer groups, enabling a calculation of direct medical costs per ulcer healed in a typical French health insurance plan. Clinical outcomes and some treatment patterns were obtained from published literature. Validations of different treatment patterns were developed using an expert consensus panel similar to the Delphi approach. Costs were calculated based on national averages and estimates from the UK and Germany. The models were used to measure costs per healed ulcer over a 12-week period. For both the pressure ulcer and venous leg ulcer models, three protocols of care were identified. For pressure ulcers and venous leg ulcers, the hydrocolloid DuoDERM (ConvaTec, also known as Granuflex in the UK and Varihesive in Germany) was most cost-effective in France. The combination of published data and expert consensus opinion is a valid technique, and in this case suggests that treating pressure ulcers and venous leg ulcers with hydrocolloid dressings is more cost-effective than treating them with saline gauze, in spite of the lower unit cost of the latter.

Effect of External Pressure and Catheter Gauge on Flow Rate, Kinetic Energy, and Endothelial Injury During Intravenous Fluid Administration in a Rabbit Model.

PubMed

Hu, Mei-Hua; Chan, Wei-Hung; Chen, Yao-Chang; Cherng, Chen-Hwan; Lin, Chih-Kung; Tsai, Chien-Sung; Chou, Yu-Ching; Huang, Go-Shine

2016-01-01

The effects of intravenous (IV) catheter gauge and pressurization of IV fluid (IVF) bags on fluid flow rate have been studied. However, the pressure needed to achieve a flow rate equivalent to that of a 16 gauge (G) catheter through smaller G catheters and the potential for endothelial damage from the increased kinetic energy produced by higher pressurization are unclear. Constant pressure on an IVF bag was maintained by an automatic adjustable pneumatic pressure regulator of our own design. Fluids running through 16 G, 18 G, 20 G, and 22 G catheters were assessed while using IV bag pressurization to achieve the flow rate equivalent to that of a 16 G catheter. We assessed flow rates, kinetic energy, and flow injury to rabbit inferior vena cava endothelium. By applying sufficient external constant pressure to an IVF bag, all fluids could be run through smaller (G) catheters at the flow rate in a 16 G catheter. However, the kinetic energy increased significantly as the catheter G increased. Damage to the venous endothelium was negligible or minimal/patchy cell loss. We designed a new rapid infusion system, which provides a constant pressure that compresses the fluid volume until it is free from visible residual fluid. When large-bore venous access cannot be obtained, multiple smaller catheters, external pressure, or both should be considered. However, caution should be exercised when fluid pressurized to reach a flow rate equivalent to that in a 16 G catheter is run through a smaller G catheter because of the profound increase in kinetic energy that can lead to venous endothelium injury.

Outcomes and reliability of the flow coupler in postoperative monitoring of head and neck free flaps.

PubMed

Fujiwara, Rance J T; Dibble, Jacqueline M; Larson, Scott V; Pierce, Matthew L; Mehra, Saral

2018-04-01

To assess the accuracy and reliability of the flow coupler relative to the implantable arterial Doppler probe in postoperative monitoring of head and neck free flaps. Retrospective single-institution study, April 2015 to March 2017. Both the venous flow coupler and arterial Doppler were employed in 120 consecutive head and neck free flap cases. When Doppler signal loss occurred, flaps were evaluated by physical exam to determine whether signal loss was a true positive necessitating operating room takeback. Sensitivity, specificity, and false positive rate (FPR) were recorded for each device. Logistic regression was conducted to identify user trends over time. Eleven of 120 patients (9.2%) required takeback, 10 from venous thrombosis and one from arterial thrombosis. Permanent signal loss (PSL) occurred in the flow coupler in all takebacks; PSL occurred in the arterial Doppler only in the case of arterial thrombosis. Salvage rate was 9/11 (81.8%). For the flow coupler, sensitivity was 100%, specificity 86.4%, and FPR 13.6%. For the arterial probe, sensitivity was 9.1%, specificity 97.1%, and FPR 2.9%. A 4.1% decrease in false positives with each additional flow coupler use was observed. Monitoring the vein via flow coupler has high sensitivity in identifying vascular compromise compared to the arterial probe, especially for venous thrombosis. There is moderate FPR; this decreases with increased usage and, when supplemented with physical examination, does not result in unnecessary takebacks. The flow coupler can be a valuable tool in postoperative monitoring of head and neck free flaps. 4. Laryngoscope, 128:812-817, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Beta-Blockers: An Abstracted Bibliography.

DTIC Science & Technology

1989-04-04

on subjects in the supine position. Blood flow was measured by venous occlusion plethys- mography. Prugs were administered via indwelling catheter (one...PROCEDURES: Noninvasive measuremert of maximum oxygen intake, invasive measurement of systemic and pulmonary arterial pressures, arterial and mixed venous ...ratio was approximately 0.1:1. Central nervous system-related effects associated with propranolol and metoprolol appear to be the result of high brain

Role of Color Flow Ultrasound in Detection of Deep Venous Thrombosis

ERIC Educational Resources Information Center

Mohammed, Shelan Hakeem; AL-Najjar, Salwa A.

2016-01-01

Background: Deep vein thrombosis (DVT) of lower limbs is one of the most causes for the majority of death caused by pulmonary embolism. Many medical and surgical disorders are complicated by DVT. Most venous thrombi are clinically silent. B-mode and color Doppler imaging is needed for early diagnosis of DVT to prevent complications and squeal of…

Venous malformations of the head and neck: current concepts in management.

PubMed

Fowell, C; Verea Linares, C; Jones, R; Nishikawa, H; Monaghan, A

2017-01-01

Low-flow venous malformations are congenital lesions and they are the third most common vascular anomaly in the head and neck. In this paper, the third in a series of three educational reviews, we discuss current trends in their management, and include a summary of common sclerosant agents used in their control. Copyright © 2016. Published by Elsevier Ltd.

Platelets Drive Thrombus Propagation in a Hematocrit and Glycoprotein VI-Dependent Manner in an In Vitro Venous Thrombosis Model.

PubMed

Lehmann, Marcus; Schoeman, Rogier M; Krohl, Patrick J; Wallbank, Alison M; Samaniuk, Joseph R; Jandrot-Perrus, Martine; Neeves, Keith B

2018-05-01

The objective of this study was to measure the role of platelets and red blood cells on thrombus propagation in an in vitro model of venous valvular stasis. A microfluidic model with dimensional similarity to human venous valves consists of a sinus distal to a sudden expansion, where for sufficiently high Reynolds numbers, 2 countercurrent vortices arise because of flow separation. The primary vortex is defined by the points of flow separation and reattachment. A secondary vortex forms in the deepest recess of the valve pocket characterized by low shear rates. An initial fibrin gel formed within the secondary vortex of a tissue factor-coated valve sinus. Platelets accumulated at the interface of the fibrin gel and the primary vortex. Red blood cells at physiological hematocrits were necessary to provide an adequate flux of platelets to support thrombus growth out of the valve sinus. A subpopulation of platelets that adhered to fibrin expose phosphatidylserine. Platelet-dependent thrombus growth was attenuated by inhibition of glycoprotein VI with a blocking Fab fragment or D-dimer. A 3-step process regulated by hemodynamics was necessary for robust thrombus propagation: First, immobilized tissue factor initiates coagulation and fibrin deposition within a low flow niche defined by a secondary vortex in the pocket of a model venous valve. Second, a primary vortex delivers platelets to the fibrin interface in a red blood cell-dependent manner. Third, platelets adhere to fibrin, activate through glycoprotein VI, express phosphatidylserine, and subsequently promote thrombus growth beyond the valve sinus and into the bulk flow. © 2018 American Heart Association, Inc.

Central venous stenosis in haemodialysis patients without a previous history of catheter placement.

PubMed

Oguzkurt, Levent; Tercan, Fahri; Yildirim, Sedat; Torun, Dilek

2005-08-01

To evaluate dialysis history, imaging findings and outcome of endovascular treatment in six patients with central venous stenosis without a history of previous catheter placement. Between April 2000 and June 2004, six (10%) of 57 haemodialysis patients had stenosis of a central vein without a previous central catheter placement. Venography findings and outcome of endovascular treatment in these six patients were retrospectively evaluated. Patients were three women (50%) and three men aged 32-60 years (mean age: 45 years) and all had massive arm swelling as the main complaint. The vascular accesses were located at the elbow in five patients and at the wrist in one patient. Three patients had stenosis of the left subclavian vein and three patients had stenosis of the left brachiocephalic vein. The mean duration of the vascular accesses from the time of creation was 25.1 months. Flow volumes of the vascular access were very high in four patients who had flow volume measurement. The mean flow volume was 2347 ml/min. One of three patients with brachiocephalic vein stenosis had compression of the vein by the brachiocephalic artery. All the lesions were first treated with balloon angioplasty and two patients required stent placement on long term. Number of interventions ranged from 1 to 4 (mean: 2.1). Symptoms resolved in five patients and improved in one patient who had a stent placed in the left BCV. Central venous stenosis in haemodialysis patients without a history of central venous catheterization tends to occur or be manifested in patients with a proximal permanent vascular access with high flow rates. Balloon angioplasty with or without stent placement offers good secondary patency rates in mid-term.

Pulmonary venous flow determinants of left atrial pressure under different loading conditions in a chronic animal model with mitral regurgitation

NASA Technical Reports Server (NTRS)

Yang, Hua; Jones, Michael; Shiota, Takahiro; Qin, Jian Xin; Kim, Yong Jin; Popovic, Zoran B.; Pu, Min; Greenberg, Neil L.; Cardon, Lisa A.; Eto, Yoko;

4D flow mri post-processing strategies for neuropathologies

NASA Astrophysics Data System (ADS)

Schrauben, Eric Mathew

4D flow MRI allows for the measurement of a dynamic 3D velocity vector field. Blood flow velocities in large vascular territories can be qualitatively visualized with the added benefit of quantitative probing. Within cranial pathologies theorized to have vascular-based contributions or effects, 4D flow MRI provides a unique platform for comprehensive assessment of hemodynamic parameters. Targeted blood flow derived measurements, such as flow rate, pulsatility, retrograde flow, or wall shear stress may provide insight into the onset or characterization of more complex neuropathologies. Therefore, the thorough assessment of each parameter within the context of a given disease has important medical implications. Not surprisingly, the last decade has seen rapid growth in the use of 4D flow MRI. Data acquisition sequences are available to researchers on all major scanner platforms. However, the use has been limited mostly to small research trials. One major reason that has hindered the more widespread use and application in larger clinical trials is the complexity of the post-processing tasks and the lack of adequate tools for these tasks. Post-processing of 4D flow MRI must be semi-automated, fast, user-independent, robust, and reliably consistent for use in a clinical setting, within large patient studies, or across a multicenter trial. Development of proper post-processing methods coupled with systematic investigation in normal and patient populations pushes 4D flow MRI closer to clinical realization while elucidating potential underlying neuropathological origins. Within this framework, the work in this thesis assesses venous flow reproducibility and internal consistency in a healthy population. A preliminary analysis of venous flow parameters in healthy controls and multiple sclerosis patients is performed in a large study employing 4D flow MRI. These studies are performed in the context of the chronic cerebrospinal venous insufficiency hypothesis. Additionally, a double-gated flow acquisition and reconstruction scheme demonstrates respiratory-induced changes in internal jugular vein flow. Finally, a semi-automated intracranial vessel segmentation and flow parameter measurement software tool for fast and consistent 4D flow post-processing analysis is developed, validated, and exhibited an in-vivo.

Chronic leg ulceration in homozygous sickle cell disease: the role of venous incompetence.

PubMed

Clare, Andrea; FitzHenley, Michael; Harris, June; Hambleton, Ian; Serjeant, Graham R

2002-11-01

Chronic leg ulceration is a common cause of morbidity in Jamaican patients with homozygous sickle cell (SS) disease. Ulcers heal more rapidly on bed rest and deteriorate on prolonged standing, suggesting a role of venous hypertension in their persistence. This hypothesis has been tested by Doppler detection of venous competence in SS patients and in matched controls with a normal haemoglobin (AA) genotype in the Jamaican Cohort Study. Venous incompetence was significantly more frequent in SS disease [137/183 (75%)] than in non-pregnant AA controls [53/137 (39%)]. Past or present ulceration occurred in 78 (43%) SS patients, with a highly significant association between leg ulceration and venous incompetence in the same leg (P < 0.001). Prominence and/or varicosities of the veins and spontaneous leg ulcers were more common among patients with multiple sites of incompetence. The association of venous incompetence with chronic leg ulceration identifies a further pathological mechanism contributing to the morbidity of SS disease. The cause of venous incompetence is unknown but the sluggish circulation associated with dependency, turbidity and impaired linear flow at venous valves, hypoxia-induced sickling, the rheological effects of high white cell counts, and activation of components of the coagulation system may all contribute. Venous hypertension in SS patients with leg ulceration suggests that firm elastic supportive dressings might promote healing of chronic leg ulcers.

A 1D pulse wave propagation model of the hemodynamics of calf muscle pump function.

PubMed

Keijsers, J M T; Leguy, C A D; Huberts, W; Narracott, A J; Rittweger, J; van de Vosse, F N

2015-07-01

The calf muscle pump is a mechanism which increases venous return and thereby compensates for the fluid shift towards the lower body during standing. During a muscle contraction, the embedded deep veins collapse and venous return increases. In the subsequent relaxation phase, muscle perfusion increases due to increased perfusion pressure, as the proximal venous valves temporarily reduce the distal venous pressure (shielding). The superficial and deep veins are connected via perforators, which contain valves allowing flow in the superficial-to-deep direction. The aim of this study is to investigate and quantify the physiological mechanisms of the calf muscle pump, including the effect of venous valves, hydrostatic pressure, and the superficial venous system. Using a one-dimensional pulse wave propagation model, a muscle contraction is simulated by increasing the extravascular pressure in the deep venous segments. The hemodynamics are studied in three different configurations: a single artery-vein configuration with and without valves and a more detailed configuration including a superficial vein. Proximal venous valves increase effective venous return by 53% by preventing reflux. Furthermore, the proximal valves shielding function increases perfusion following contraction. Finally, the superficial system aids in maintaining the perfusion during the contraction phase and reduces the refilling time by 37%. © 2015 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.

Central venous catheter integrity during mechanical power injection of iodinated contrast medium.

PubMed

Macha, Douglas B; Nelson, Rendon C; Howle, Laurens E; Hollingsworth, John W; Schindera, Sebastian T

2009-12-01

To evaluate a widely used nontunneled triple-lumen central venous catheter in order to determine whether the largest of the three lumina (16 gauge) can tolerate high flow rates, such as those required for computed tomographic angiography. Forty-two catheters were tested in vitro, including 10 new and 32 used catheters (median indwelling time, 5 days). Injection pressures were continuously monitored at the site of the 16-gauge central venous catheter hub. Catheters were injected with 300 and 370 mg of iodine per milliliter of iopamidol by using a mechanical injector at increasing flow rates until the catheter failed. The infusion rate, hub pressure, and location were documented for each failure event. The catheter pressures generated during hand injection by five operators were also analyzed. Mean flow rates and pressures at failure were compared by means of two-tailed Student t test, with differences considered significant at P < .05. Injections of iopamidol with 370 mg of iodine per milliliter generate more pressure than injections of iopamidol with 300 mg of iodine per milliliter at the same injection rate. All catheters failed in the tubing external to the patient. The lowest flow rate at which catheter failure occurred was 9 mL/sec. The lowest hub pressure at failure was 262 pounds per square inch gauge (psig) for new and 213 psig for used catheters. Hand injection of iopamidol with 300 mg of iodine per milliliter generated peak hub pressures ranging from 35 to 72 psig, corresponding to flow rates ranging from 2.5 to 5.0 mL/sec. Indwelling use has an effect on catheter material property, but even for used catheters there is a substantial safety margin for power injection with the particular triple-lumen central venous catheter tested in this study, as the manufacturer's recommendation for maximum pressure is 15 psig.

[Sequelae of unilateral deep venous thrombosis in plethysmography of the calf].

PubMed

Zicot, M; Depairon, M

1982-01-01

Twenty four patients suffering from unilateral venous disturbances revealed by Doppler and secondary to a deep venous thrombosis were examined. The calf venous haemodynamics was analyzed by use of a strain-jauge plethysmograph. We determined the increase in venous volume due to the inflation of a thigh pneumatic cuff (pressure at 20, 40 and 60 mm Hg; delta V20, delta V40, delta V60). The maximal venous output (Vout) was measured after a quick release of the 60 mm Hg pressure. The maximal venous drainage (VMM) was assessed during a rhythmic exercise (tiptoeing) while standing; delta V20, delta V40 and delta V60 were nearly constantly reduced on the abnormal side (t of Student respectively 3.49; 6.09 and 5.07). Vout dropped proportionaly to delta V60. Some abnormalities due to valvular insufficiency were frequently present in the beginning of the inflation curve at the level of the abnormal limbs. VMM was nearly always largely decreased on the affected side (t = 5.43). The unilateral flow disturbances displayed by the Doppler were regularly going with abnormalities of the capacitive system, well demonstrated by comparison with the non-affected limbs.

Venous compression syndrome of internal jugular veins prevalence in patients with multiple sclerosis and chronic cerebro-spinal venous insufficiency.

PubMed

Mandolesi, Sandro; Niglio, Tarcisio; Orsini, Augusto; De Sio, Simone; d'Alessandro, Alessandro; Mandolesi, Dimitri; Fedele, Francesco; d'Alessandro, Aldo

2016-01-01

Analysis of the incidence of Venous Compression Syndrome (VCS) with full block of the flow of the internal jugular veins (IJVs) in patients with Multiple Sclerosis and Chronic cerebro-spinal venous insufficiency. We included 769 patients with MS and CCSVI (299 males, 470 females) and 210 controls without ms and ccsvi (92 males, 118 females). each subject was investigated by echo-color-doppler (ecd). morphological and hemodynamic ecd data were recorded by a computerized mem-net maps of epidemiological national observatory on ccsvi and they were analyzed by mem-net clinical analysis programs. VCS of IJVs occurs in 240 subjects affected by CCSVI and MS (31% of total) and in 12 controls (6% of total). The differences between the two groups are statistical significant (X² = 36.64, p<0.0001). Up to day there are no longitudinal studies that allow us to identify the WC of jugular and/or vertebral veins as etiology of a chronic neurodegenerative disease, but we note that Venous Compression Syndrome of IJVs is strongly associated with MS and CCSVI. Chronic Cerebro-Spinal Venous Insufficiency, Multiple Sclerosis, Venous Compression Syndrome.

Determination of fractional flow reserve (FFR) based on scaling laws: a simulation study

NASA Astrophysics Data System (ADS)

Wong, Jerry T.; Molloi, Sabee

2008-07-01

Fractional flow reserve (FFR) provides an objective physiological evaluation of stenosis severity. A technique that can measure FFR using only angiographic images would be a valuable tool in the cardiac catheterization laboratory. To perform this, the diseased blood flow can be measured with a first pass distribution analysis and the theoretical normal blood flow can be estimated from the total coronary arterial volume based on scaling laws. A computer simulation of the coronary arterial network was used to gain a better understanding of how hemodynamic conditions and coronary artery disease can affect blood flow, arterial volume and FFR estimation. Changes in coronary arterial flow and volume due to coronary stenosis, aortic pressure and venous pressure were examined to evaluate the potential use of flow and volume for FFR determination. This study showed that FFR can be estimated using arterial volume and a scaling coefficient corrected for aortic pressure. However, variations in venous pressure were found to introduce some error in FFR estimation. A relative form of FFR was introduced and was found to cancel out the influence of pressure on coronary flow, arterial volume and FFR estimation. The use of coronary flow and arterial volume for FFR determination appears promising.

Successful embolization using interlocking detachable coils for a congenital extrahepatic portosystemic venous shunt in a child.

PubMed

Yamagami, Takuji; Yoshimatsu, Rika; Matsumoto, Tomohiro; Terayama, Koshi; Nishiumra, Akira; Maeda, Yousuke; Nishimura, Tsunehiko

2007-11-01

The authors report the case of a 6-year-old boy with a congenital extrahepatic portosystemic venous shunt. He had hyperammonemia. The shunt was 18 mm in diameter and located between the inferior mesenteric vein and the left internal iliac vein. The flow in the shunt was very rapid. After decreasing blood flow by inflating a balloon catheter inserted into the left internal iliac vein from the femoral vein, a microcatheter was coaxially advanced to the shunt to embolize the shunt. Embolization was successfully performed with interlocking detachable coils and microcoils without any complication. This patient's hyperammonemia resolved soon after the procedure.

Mixing problems in using indicators for measuring regional blood flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ushioda, E.; Nuwayhid, B.; Tabsh, K.

A basic requirement for using indicators for measuring blood flow is adequate mixing of the indicator with blood prior to sampling the site. This requirement has been met by depositing the indicator in the heart and sampling from an artery. Recently, authors have injected microspheres into veins and sampled from venous sites. The present studies were designed to investigate the mixing problems in sheep and rabbits by means of Cardio-Green and labeled microspheres. The indicators were injected at different points in the circulatory system, and blood was sampled at different levels of the venous and arterial systems. Results show themore » following: (a) When an indicator of small molecular size (Cardio-Green) is allowed to pass through the heart chambers, adequate mixing is achieved, yielding accurate and reproducible results. (b) When any indicator (Cardio-Green or microspheres) is injected into veins, and sampling is done at any point in the venous system, mixing is inadequate, yielding flow results which are inconsistent and erratic. (c) For an indicator or large molecular size (microspheres), injecting into the left side of the heart and sampling from arterial sites yield accurate and reproducible results regardless of whether blood is sampled continuously or intermittently.« less

Noninvasive measurement of central venous pressure

NASA Technical Reports Server (NTRS)

Webster, J. G.; Mastenbrook, S. M., Jr.

1972-01-01

A technique for the noninvasive measurement of CVP in man was developed. The method involves monitoring venous velocity at a point in the periphery with a transcutaneous Doppler ultrasonic velocity meter while the patient performs a forced expiratory maneuver. The idea is the CVP is related to the value of pressure measured at the mouth which just stops the flow in the vein. Two improvements were made over the original procedure. First, the site of venous velocity measurement was shifted from a vein at the antecubital fossa (elbow) to the right external jugular vein in the neck. This allows for sensing more readily events occurring in the central veins. Secondly, and perhaps most significantly, a procedure for obtaining a curve of relative mean venous velocity vs mouth pressure was developed.

Orbital venous malformation: percutaneous treatment using an electrolytically detachable fibred coil.

PubMed

Diolaiuti, Sara; Iizuka, Tateyuki; Schroth, Gerhard; Remonda, Luca; Laedrach, Kurt; El-Koussy, Marwan; Frueh, Beatrice E; Goldblum, David

2009-03-01

To report the efficacy of percutaneous treatment of an orbital venous malformation with an electrolytically detachable fibred coil. We report an instance of radiography-guided percutaneous treatment with an electrolytically detachable fibred coil in a 16-year-old boy with acute, spontaneous, painless proptosis on the left side, which progressed with time. Magnetic resonance imaging, angiography and orbitophlebography revealed a low-flow, intraorbital venous malformation. Percutaneous puncture and drainage were followed by a short remission. Following an acute recurrence, a single detachable fibred coil was deployed via a percutaneous approach under angiographic guidance. No radiological or clinical recurrences were observed over 4 years. Embolization of a deep orbital venous malformation with detachable fibred coils via a percutaneous approach can be highly effective, and may be considered before proceeding with open surgery.

Modeling of heat transfer in a vascular tissue-like medium during an interstitial hyperthermia process.

PubMed

Hassanpour, Saeid; Saboonchi, Ahmad

2016-12-01

This paper aims to evaluate the role of small vessels in heat transfer mechanisms of a tissue-like medium during local intensive heating processes, for example, an interstitial hyperthermia treatment. To this purpose, a cylindrical tissue with two co- and counter-current vascular networks and a central heat source is introduced. Next, the energy equations of tissue, supply fluid (arterial blood), and return fluid (venous blood) are derived using porous media approach. Then, a 2D computer code is developed to predict the temperature of blood (fluid phase) and tissue (solid phase) by conventional volume averaging method and a more realistic solution method. In latter method, despite the volume averaging the blood of interconnect capillaries is separated from the arterial and venous blood phases. It is found that in addition to blood perfusion rate, the arrangement of vascular network has considerable effects on the pattern and amount of the achieved temperature. In contrast to counter-current network, the co-current network of vessels leads to considerable asymmetric pattern of temperature contours and relocation of heat affected zone along the blood flow direction. However this relocation can be prevented by changing the site of hyperthermia heat source. The results show that the cooling effect of co-current blood vessels during of interstitial heating is more efficient. Despite much anatomical dissimilarities, these findings can be useful in designing of protocols for hyperthermia cancer treatment of living tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of giant-sized flow-through venous flap for simultaneous reconstruction of dual or multiple major arteries in salvage therapy for complex upper limb traumatic injury.

PubMed

Zheng, Da-Wei; Li, Zhang-Can; Shi, Rong-Jian; Sun, Feng; Xu, Li; Shou, Kui-Shui

2016-02-01

Salvage repair after complex upper limb traumatic injury is surgically challenging due to underlying major arterial impairment with complicating a large-sized soft tissue defect. The purpose of this study was to evaluate the effectiveness and safety of using a giant-sized (≥100 cm(2)) flow-through venous flap for reconstruction of dual or multiple forearm, metacarpal, or digital arteries after complex upper limb traumatic injury. Seven patients were consecutively hospitalized for emergency salvage repair after complex upper limb traumatic injury between March 2012 and May 2014. The forearm and palmar artery defects were repaired using the calf great saphenous vein flap and the volar forearm venous flap, respectively. The flow-through venous flap ranged from 9.5 cm × 12.0 cm to 12.0 cm × 20.0 cm (mean, 158.4 cm(2)) in size. The flaps and affected limbs survived uneventfully in five patients, with one patient experiencing distal flap marginal necrosis and a second patient requiring amputation of the affected limb. Computed tomography angiography showed patent vessels in all patients. The mean total active motion of the repaired fingers was 199.5° versus 258.8° for the contralateral counterpart (77.1%). The sensory return was determined to be S2 in 2 patients, S3 in 3 patients and S3+ in 1 patient. The disability scores for the arm, shoulder, and hand ranged from 4.6-18.2 (mean, 11.3), and the mean Michigan hand outcomes questionnaire score was 7.8 ± 0.9. The flow-through venous flap is an effective and safe treatment alternative for salvage therapy of a ≥100-cm(2) complex upper limb traumatic injury with dual or multiple major arterial impairment. This technique allows simultaneous reconstruction of dual or multiple artery injuries and an extensive soft tissue defect. Serious surgical site infection remains a major safety concern and necessitates radical debridement in complicating cases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitrite and S-Nitrosohemoglobin Exchange Across the Human Cerebral and Femoral Circulation: Relationship to Basal and Exercise Blood Flow Responses to Hypoxia.

PubMed

Bailey, Damian M; Rasmussen, Peter; Overgaard, Morten; Evans, Kevin A; Bohm, Aske M; Seifert, Thomas; Brassard, Patrice; Zaar, Morten; Nielsen, Henning B; Raven, Peter B; Secher, Niels H

2017-01-10

The mechanisms underlying red blood cell (RBC)-mediated hypoxic vasodilation remain controversial, with separate roles for nitrite () and S-nitrosohemoglobin (SNO-Hb) widely contested given their ability to transduce nitric oxide bioactivity within the microcirculation. To establish their relative contribution in vivo, we quantified arterial-venous concentration gradients across the human cerebral and femoral circulation at rest and during exercise, an ideal model system characterized by physiological extremes of O 2 tension and blood flow. Ten healthy participants (5 men, 5 women) aged 24±4 (mean±SD) years old were randomly assigned to a normoxic (21% O 2 ) and hypoxic (10% O 2 ) trial with measurements performed at rest and after 30 minutes of cycling at 70% of maximal power output in hypoxia and equivalent relative and absolute intensities in normoxia. Blood was sampled simultaneously from the brachial artery and internal jugular and femoral veins with plasma and RBC nitric oxide metabolites measured by tri-iodide reductive chemiluminescence. Blood flow was determined by transcranial Doppler ultrasound (cerebral blood flow) and constant infusion thermodilution (femoral blood flow) with net exchange calculated via the Fick principle. Hypoxia was associated with a mild increase in both cerebral blood flow and femoral blood flow (P<0.05 versus normoxia) with further, more pronounced increases observed in femoral blood flow during exercise (P<0.05 versus rest) in proportion to the reduction in RBC oxygenation (r=0.680-0.769, P<0.001). Plasma gradients reflecting consumption (arterial>venous; P<0.05) were accompanied by RBC iron nitrosylhemoglobin formation (venous>arterial; P<0.05) at rest in normoxia, during hypoxia (P<0.05 versus normoxia), and especially during exercise (P<0.05 versus rest), with the most pronounced gradients observed across the bioenergetically more active, hypoxemic, and acidotic femoral circulation (P<0.05 versus cerebral). In contrast, we failed to observe any gradients consistent with RBC SNO-Hb consumption and corresponding delivery of plasma S-nitrosothiols (P>0.05). These findings suggest that hypoxia and, to a far greater extent, exercise independently promote arterial-venous delivery gradients of intravascular nitric oxide, with deoxyhemoglobin-mediated reduction identified as the dominant mechanism underlying hypoxic vasodilation. © 2016 American Heart Association, Inc.

An estimation of intracranial blood flow in the new-born infant.

PubMed Central

Cross, K W; Dear, P R; Hathorn, M K; Hyams, A; Kerslake, D M; Milligan, D W; Rahilly, P M; Stothers, J K

1979-01-01

1. A non-invasive method for the estimation of the intracranial blood flow of the new-born infant is described, and results obtained with it are presented. 2. The technique is a novel application of the principle of blood flow measurement by venous occlusion plethysmography. It is possible to apply a plethysmographic technique to the neonatal cranium because the presence of open sutures between the component bones permits small, but readily measurable, changes in intracranial volume to occur. 3. Skull volume changes are calculated from changes in the occipito-frontal circumference of the cranium as recorded and measured with a mercury-in-Silastic strain gauge. 4. The jugular veins in the baby's neck are occluded by finger pressure and there follows an increase in skull volume, which is rapid at first, but which decreases exponentially as venous drainage diverts to non-occluded channels such as the vertebral venous plexus. At the instant of jugular occlusion the rate of skull volume increase is representative of the rate of flow in the jugular vessels prior to occlusion, and so provides an index of the relative magnitude of the intracranial blood flow. The method thus allows changes in intracranial blood flow to be followed. When occlusion is released cranial volume decreases, initially rapidly, but slowing exponentially as resting volume is regained. 5. A theoretical model of the events occurring during the inflow and outflow phases has been developed, and a formula derived which allows an estimation to be made of the flow of blood through uncompressed channels. The measured value of jugular blood flow can then be augmented to an estimate of total intracranial flow. 6. The mean cerebral blood flow of sixteen normal babies was estimated to be 40 ml. 100 g-1.min-1 (S.D. = +/- 11.63). Images Fig. 2 Fig. 6 PMID:458665

Idiopathic sudden sensorineural hearing loss and ménière syndrome: The role of cerebral venous drainage.

PubMed

Ciccone, M M; Scicchitano, P; Gesualdo, M; Cortese, F; Zito, A; Manca, F; Boninfante, B; Recchia, P; Leogrande, D; Viola, D; Damiani, M; Gambacorta, V; Piccolo, A; De Ceglie, V; Quaranta, N

2018-02-01

To evaluate the influence of cerebral venous drainage on the pathogenesis of idiopathic sudden sensorineural hearing loss (ISSHL) and Ménière syndrome (MD). Observational, prospective, cohort study. ENT and Cardiology Departments (University of Bari, Policlinico Hospital, Bari, Italy). We enrolled 59 consecutive patients (32 males, mean age 53.05 + 15.37 years): 40 ISSHL and 19 MD. All patients underwent physical examination, biochemical evaluation (glycemic and lipid profile, viral serology, C reactive protein, etc), audiometric (tonal, vocal, vestibular evoked myogenic potentials and auditory brainstem response test) and impedentiometric examination. The pure tone average (PTA) was calculated for the following frequencies: 250, 500, 1000, 2000, 3000, 4000, 8000. An echo-color Doppler evaluation of the venous cerebral veins, internal jugular (IJV) and vertebral veins (VV) at supine and 90° position was performed. No morphological alterations were found both in patients and controls. There were no signs of stenosis, blocked flow, membranes, etc. We found lower minimum, mean and maximum velocities in distal IJVs (P = .019; P = .013; P = .022; respectively) and left VVs (P = .027; P = .008; P = .001; respectively) in supine (0°) position in both MD and ISSHL patients as compared to controls. The same was for orthostatic position (90°). We found negative correlations between the velocities in extracranial veins and PTA values: therefore, the worst the audiometric performance of the subjects, the lower the velocities in the venous cerebral drainage. Idiopathic sudden sensorineural hearing loss and Ménière syndrome patients showed altered venous flow in IJVs and VVs as compared to controls, independently from posture. This different behavior of venous tone control can influence the ear performance and may have a role in the pathogenesis of both diseases. © 2017 John Wiley & Sons Ltd.

Endovascular Stent Treatment for Symptomatic Benign Iliofemoral Venous Occlusive Disease: Long-Term Results 1987-2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutzeit, A., E-mail: andreas.gutzeit@ksw.ch; Zollikofer, Ch. L., E-mail: Christoph.Zollikofer@ksb.ch; Dettling-Pizzolato, M., E-mail: Mira.Dettling@ksw.ch

Venous stenting has been shown to effectively treat iliofemoral venous obstruction with good short- and mid-term results. The aim of this study was to investigate long-term clinical outcome and stent patency. Twenty patients were treated with venous stenting for benign disease at our institution between 1987 and 2005. Fifteen of 20 patients (15 female, mean age at time of stent implantation 38 years [range 18-66]) returned for a clinical visit, a plain X-ray of the stent, and a Duplex ultrasound. Four patients were lost to follow-up, and one patient died 277 months after stent placement although a good clinical resultmore » was documented 267 months after stent placement. Mean follow-up after stent placement was 167.8 months (13.9 years) (range 71 (6 years) to 267 months [22 years]). No patient needed an additional venous intervention after stent implantation. No significant difference between the circumference of the thigh on the stented side (mean 55.1 cm [range 47.0-70.0]) compared with the contralateral thigh (mean 54.9 cm [range 47.0-70.0]) (p = 0.684) was seen. There was a nonsignificant trend toward higher flow velocities within the stent (mean 30.8 cm/s [range 10.0-48.0]) and the corresponding vein segment on the contralateral side (mean 25.2 cm/s [range 12.0-47.0]) (p = 0.065). Stent integrity was confirmed in 14 of 15 cases. Only one stent showed a fracture, as documented on x-ray, without any impairment of flow. Venous stenting using Wallstents showed excellent long-term clinical outcome and primary patency rate.« less

Effects of head down tilt on episcleral venous pressure in a rabbit model.

PubMed

Lavery, W J; Kiel, J W

2013-06-01

In humans, changing from upright to supine elicits an approximately 10 mmHg increase in cephalic venous pressure caused by the hydrostatic column effect, but episcleral venous pressure (EVP) and intraocular pressure (IOP) rise by only a few mmHg. The dissociation of the small increases in IOP and EVP compared to the larger increase in cephalic venous pressure suggests a regulatory mechanism controlling EVP. The aim of the present study was to determine if the rabbit model is suitable to study the effects of postural changes on EVP despite its short hydrostatic column. In anesthetized rabbits (n = 43), we measured arterial pressure (AP), IOP, and orbital venous pressure (OVP) by direct cannulation; carotid blood flow (BFcar) by transit time ultrasound, heart rate (HR) by digital cardiotachometer, and EVP with a servonull micropressure system. The goal of the protocol was to obtain measurement of supine EVP for ≈10 min, followed by ≈10 min of EVP measurement with the rabbit in a head down tilt. The data were analyzed by paired t-tests and the results reported as the mean ± standard error of the mean. In a separate group of animals (n = 35), aqueous flow was measured by fluorophotometry. This protocol entailed measurement of aqueous flow in the supine position for ≈60 min, followed by ≈60 min of aqueous flow measurement with the rabbit in a head down tilt. From supine to head down tilt, AP and BFcar were unchanged, IOP increased by 2.3 ± 0.4 mmHg (p < 0.001), EVP increased by 2.4 ± 0.4 mmHg (p < 0.001), OVP increased by 2.5 ± 0.2 mmHg (p < 0.001) and HR decreased by 9 ± 3 bpm (p = 0.002). Head down tilt caused no significant change in aqueous flow. Although the hydrostatic column in the rabbit is shorter than humans, the rabbit model permits sufficiently sensitive measurements of the pressures and systemic parameters likely involved in the EVP responses to posture change. The present results indicate directionally similar EVP and IOP responses to tilt as occur in humans and, as in humans, the responses are smaller than would be expected from the change in the hydrostatic column height. Also, as in humans, the model reveals no change in aqueous flow during head down tilt. We conclude the rabbit model is appropriate for studying the mechanisms responsible for the relative immunity of EVP and IOP to posture change. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of Gravity on Blood Volume and Flow Distribution

NASA Technical Reports Server (NTRS)

Pendergast, D.; Olszowka, A.; Bednarczyk, E.; Shykoff, B.; Farhi, L.

1999-01-01

In our previous experiments during NASA Shuttle flights SLS 1 and 2 (9-15 days) and EUROMIR flights (30-90 days) we observed that pulmonary blood flow (cardiac output) was elevated initially, and surprisingly remained elevated for the duration of the flights. Stroke volume increased initially and then decreased, but was still above 1 Gz values. As venous return was constant, the changes in SV were secondary to modulation of heart rate. Mean blood pressure was at or slightly below 1 Gz levels in space, indicating a decrease in total peripheral resistance. It has been suggested that plasma volume is reduced in space, however cardiac output/venous return do not return to 1 Gz levels over the duration of flight. In spite of the increased cardiac output, central venous pressure was not elevated in space. These data suggest that there is a change in the basic relationship between cardiac output and central venous pressure, a persistent "hyperperfusion" and a re-distribution of blood flow and volume during space flight. Increased pulmonary blood flow has been reported to increase diffusing capacity in space, presumably due to the improved homogeneity of ventilation and perfusion. Other studies have suggested that ventilation may be independent of gravity, and perfusion may not be gravity- dependent. No data for the distribution of pulmonary blood volume were available for flight or simulated microgravity. Recent studies have suggested that the pulmonary vascular tree is influenced by sympathetic tone in a manner similar to that of the systemic system. This implies that the pulmonary circulation is dilated during microgravity and that the distribution of blood flow and volume may be influenced more by vascular control than by gravity. The cerebral circulation is influenced by sympathetic tone similarly to that of the systemic and pulmonary circulations; however its effects are modulated by cerebral autoregulation. Thus it is difficult to predict if cerebral perfusion is increased and if there is edema in space. Anecdotal evidence suggests there may be cerebral edema early in flight. Cerebral artery velocity has been shown to be elevated in simulated microgravity. The elevated cerebral artery velocity during simulated microgravity may reflect vasoconstriction of the arteries and not increased cerebral blood flow. The purpose of our investigations was to evaluate the effects of alterations in simulated gravity (+/-), resulting in changes in cardiac output (+/-), and on the blood flow and volume distribution in the lung and brain of human subjects. The first hypothesis of these studies was that blood flow and volume would be affected by gravity, but their distribution in the lung would be independent of gravity and due to vasoactivity changing vascular resistance in lung vessels. The vasodilitation of the lung vasculature (lower resistance) along with increased "compliance" of the heart could account for the absence of increased central venous pressure in microgravity. Secondly, we postulate that cerebral blood velocity is increased in microgravity due to large artery vasoconstriction, but that cerebral blood flow would be reduced due to autoregulation.

New, Virtually Wall-less Cannulas Designed for Augmented Venous Drainage in Minimally Invasive Cardiac Surgery.

PubMed

von Segesser, Ludwig Karl; Berdajs, Denis; Abdel-Sayed, Saad; Tozzi, Piergiorgio; Ferrari, Enrico; Maisano, Francesco

2016-01-01

Inadequate venous drainage during minimally invasive cardiac surgery becomes most evident when the blood trapped in the pulmonary circulation floods the surgical field. The present study was designed to assess the in vivo performance of new, thinner, virtually wall-less, venous cannulas designed for augmented venous drainage in comparison to traditional thin-wall cannulas. Remote cannulation was realized in 5 bovine experiments (74.0 ± 2.4 kg) with percutaneous venous access over the wire, serial dilation up to 18 F and insertion of either traditional 19 F thin wall, wire-wound cannulas, or through the same access channel, new, thinner, virtually wall-less, braided cannulas designed for augmented venous drainage. A standard minimal extracorporeal circuit set with a centrifugal pump and a hollow fiber membrane oxygenator, but no in-line reservoir was used. One hundred fifty pairs of pump-flow and required pump inlet pressure values were recorded with calibrated pressure transducers and a flowmeter calibrated by a volumetric tank and timer at increasing pump speed from 1500 RPM to 3500 RPM (500-RPM increments). Pump flow accounted for 1.73 ± 0.85 l/min for wall-less versus 1.17 ± 0.45 l/min for thin wall at 1500 RPM, 3.91 ± 0.86 versus 3.23 ± 0.66 at 2500 RPM, 5.82 ± 1.05 versus 4.96 ± 0.81 at 3500 RPM. Pump inlet pressure accounted for 9.6 ± 9.7 mm Hg versus 4.2 ± 18.8 mm Hg for 1500 RPM, -42.4 ± 26.7 versus -123 ± 51.1 at 2500 RPM, and -126.7 ± 55.3 versus -313 ± 116.7 for 3500 RPM. At the well-accepted pump inlet pressure of -80 mm Hg, the new, thinner, virtually wall-less, braided cannulas provide unmatched venous drainage in vivo. Early clinical analyses have confirmed these findings.

Thrombin generation and fibrin formation under flow on biomimetic tissue factor-rich surfaces.

PubMed

Onasoga-Jarvis, A A; Puls, T J; O'Brien, S K; Kuang, L; Liang, H J; Neeves, K B

2014-01-01

Blood flow regulates coagulation and fibrin assembly by controlling the rate of transport of zymogens, enzymes and plasma proteins to and from the site of an injury. The objective of this work was to define the hemodynamic conditions under which fibrin can form under flow on tissue factor (TF)-rich substrates. TF-coated silica beads (~ 800 nm) were patterned into 18-85-μm spots. Normal pooled plasma and factors VIII, IX and XI deficient plasmas were perfused over the beads coated with 0.08, 0.8 and 8 molecules-TF μm(-2) at shear rates of 50-1000 s(-1) . Fibrin deposition and thrombin generation were measured by fluorescence microscopy in a hydrodynamic focusing microfluidic device. Fibrin deposition was supported on patterned bead spots, but not planar TF substrates at the same surface TF concentration. There was a threshold spot size and a shear rate dependent TF concentration that was necessary to support fibrin polymerization. FVIII and FIX had minor effects on fibrin dynamics at 8 molecules-TF μm(-2) , but were essential at 0.8 molecules-TF μm(-2) . The absence of FXI influenced thrombin generation and fibrin deposition at both 0.8 and 8 molecules-TF μm(-2) . These results show that fibrin deposition requires perturbations in the flow field that protect reactions from dilution by flow under venous and arterial conditions. FVIII and FIX have a modest effect on fibrin deposition at high TF concentrations, but are necessary for fibrin deposition at low TF concentrations. FXI amplifies thrombin generation under flow at both low and high TF concentrations. © 2013 International Society on Thrombosis and Haemostasis.

Rescue N-butyl-2 cyanoacrylate embolectomy using a Solitaire FR device after venous glue migration during arteriovenous malformation embolization: technical note.

PubMed

Fahed, Robert; Clarençon, Frédéric; Sourour, Nader-Antoine; Chauvet, Dorian; Le Jean, Lise; Chiras, Jacques; Di Maria, Federico

2016-07-01

One of the procedural risks in arteriovenous malformation (AVM) embolization is possible migration of the embolic agent into the venous drainage with an incomplete nidus occlusion, which may lead to severe hemorrhagic complications. This report presents the case of a 29-year-old man who presented with a deep intraparenchymal hematoma on the left side secondary to the spontaneous rupture of a claustral AVM. Upon resorption of the hematoma, the patient underwent an initial therapeutic session of N-butyl-2 cyanoacrylate endovascular embolization, with the purpose of reducing the AVM volume and flow before performing Gamma Knife radiosurgery. After glue injection into one of the arterial feeders, the control angiography showed a partial migration of the glue cast into the straight sinus, with most of the nidus still visible. Because of the bleeding risk due to possible venous hypertension, it was decided to try to retrieve the glue from the vein by using a stent retriever via jugular access. This maneuver allowed a nearly complete removal of the glue cast, thereby restoring normal venous flow drainage. The patient showed no clinical worsening after the procedure. To the authors' knowledge, this is the first report of the use of the Solitaire FR device as a rescue glue retriever. This method should be considered by physicians in cases of unintended glue migration into the venous circulation during AVM embolization.

Development and origins of zebrafish ocular vasculature.

PubMed

Kaufman, Rivka; Weiss, Omri; Sebbagh, Meyrav; Ravid, Revital; Gibbs-Bar, Liron; Yaniv, Karina; Inbal, Adi

2015-03-27

The developing eye receives blood supply from two vascular systems, the intraocular hyaloid system and the superficial choroidal vessels. In zebrafish, a highly stereotypic and simple set of vessels develops on the surface of the eye prior to development of choroidal vessels. The origins and formation of this so-called superficial system have not been described. We have analyzed the development of superficial vessels by time-lapse imaging and identified their origins by photoconversion experiments in kdrl:Kaede transgenic embryos. We show that the entire superficial system is derived from a venous origin, and surprisingly, we find that the hyaloid system has, in addition to its previously described arterial origin, a venous origin for specific vessels. Despite arising solely from a vein, one of the vessels in the superficial system, the nasal radial vessel (NRV), appears to acquire an arterial identity while growing over the nasal aspect of the eye and this happens in a blood flow-independent manner. Our results provide a thorough analysis of the early development and origins of zebrafish ocular vessels and establish the superficial vasculature as a model for studying vascular patterning in the context of the developing eye.

Pressure-flow relationships in in vitro model of compartment syndrome.

PubMed

Shrier, I; Magder, S

1995-07-01

Compartment syndrome is a condition in which an increase in intramuscular pressure decreases blood flow to skeletal muscle. According to the Starling resistor (i.e., vascular waterfall) model of blood flow, the decrease in flow could occur through an increase in arterial resistance (Rart) or an increase in the critical closing pressure (Pcrit). To determine which explains the decrease in flow, we pump perfused a canine gastrocnemius muscle placed within an airtight box, controlled box pressures (Pbox) so that flow ranged from 100 to 50%, and measured Pcrit, Rart, arterial compliance, small venular pressure (measured by the double-occlusion technique), and venous pressure. An increase in Pbox limited flow mainly through an increase in Pcrit (75-85%), with only small changes in Rart (15-25%) and no change in arterial compliance. Increases in Pbox also produced a vascular waterfall in the venous circulation, but small venular transmural pressure always remained less than control levels. We conclude that increases in Pbox mostly limit blood flow through increases in Pcrit and that Rart plays a minor role. Transmural pressure across the small venules decreases with increases in intramuscular pressure, which contradicts the currently held belief that compartment syndrome is due to a cycle of swelling-ischemia-swelling.

Regulation of the pulmonary circulation

PubMed Central

Lee, G. de J.

1971-01-01

Factors regulating pressure and flow in the lungs are reviewed with particular emphasis on their role in regulating blood flow velocity and distribution within the lung capillaries. The behaviour of the pulmonary arterial, system, alveolar capillaries, and pulmonary venous system are considered individually. The effect of heart disease on lung capillary blood flow is examined. PMID:4929437

Control of respiration-driven retrograde flow in the subdiaphragmatic venous return of the Fontan circulation

PubMed Central

Vukicevic, M; Conover, T; Jaeggli, M; Zhou, J; Pennati, G; Hsia, TY; Figliola, RS

2014-01-01

Respiration influences the subdiaphragmatic venous return in the total cavopulmonary connection (TCPC) of the Fontan circulation whereby both the inferior vena cava (IVC) and hepatic vein flows can experience retrograde motion. Controlling retrograde flows could improve patient outcomes. Using a patient-specific model within a Fontan mock circulatory system with respiration, we inserted a valve into the IVC to examine its effects on local hemodynamics while varying retrograde volumes by changing vascular impedances. A bovine valved conduit reduced IVC retrograde flow to within 3% of antegrade flow in all cases. The valve closed only under conditions supporting retrograde flow and its effects on local hemodynamics increased with larger retrograde volume. Liver and TCPC pressures improved only while the valve leaflets were closed while cycle-averaged pressures improved only slightly (italic>1 mm Hg). Increased pulmonary vascular resistance raised mean circulation pressures but the valve functioned and cardiac output improved and stabilized. Power loss across the TCPC improved by 12–15% (pbold>0.05) with a valve. The effectiveness of valve therapy is dependent on patient vascular impedance. PMID:24814833

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paulson, O.B.; Jarden, J.O.; Godtfredsen, J.

The effect of captopril on cerebral blood flow was studied in five patients with severe congestive heart failure and in five control subjects. Cerebral blood flow was measured by inhalation of /sup 133/xenon and registration of its uptake and washout from the brain by single photon emission computer tomography. In addition, cerebral (internal jugular) venous oxygen tension was determined in the controls. The measurements were made before and 15, 60, and 180 minutes after a single oral dose of captopril (6.25 mg in patients with congestive heart failure and 25 mg in controls). Despite a marked decrease in blood pressure,more » cerebral blood flow increased slightly in the patients with severe congestive heart failure. When a correction was applied to take account of a change in arterial carbon dioxide tension, however, cerebral blood flow was unchanged after captopril administration even in patients with the greatest decrease in blood pressure, in whom a decrease in cerebral blood flow might have been expected. In the controls, blood pressure was little affected by captopril, whereas a slight, but not statistically significant, decrease in cerebral blood flow was observed. The cerebral venous oxygen tension decreased concomitantly.« less

[Hemodynamic changes in portal system after transjugular intrahepatic portosystemic shunts (TIPS)].

PubMed

Li, W; Xiao, Y; Xu, H

1995-08-01

In this study portal venous flow (PVF), splenic venous flow (SPVF), hepatic artery volume (HAV), and portal pressure were measured before and after TIPS in 11 patients with portal hypertension. The results were compared with those of normal controls. In the normal controls PVF averaged 947.2 +/- 133.4ml/min, SPVF 239.6 +/- 116.3ml/min, and HAV 241.6 +/- 78.8ml/min. In the TIPS group before and after TIPS, PVF was 883.2 +/- 233.4ml/min vs. 958.7 +/- 185.2ml/min; SPVF was 448.9 +/- 111.6ml/min vs. 333.1 +/- 101.5ml/min; HVP was 225.3 +/- 122.7ml/min vs. 249.3 +/- 103.8ml/min. Portal pressure dropped from 3.94kPa +/- 0.46 to 2.52 +/- 0.60kPa after TIPS. We conclude that in patients after TIPS portal pressure drops blood flow in the truck of the portal vein increases, flow of hepatic tissue decreases, and blood flow in splenic vein decreases. Blood flow in hepatic aftery was not significantly changed.

Computer Simulations of the Tumor Vasculature: Applications to Interstitial Fluid Flow, Drug Delivery, and Oxygen Supply.

PubMed

Welter, Michael; Rieger, Heiko

2016-01-01

Tumor vasculature, the blood vessel network supplying a growing tumor with nutrients such as oxygen or glucose, is in many respects different from the hierarchically organized arterio-venous blood vessel network in normal tissues. Angiogenesis (the formation of new blood vessels), vessel cooption (the integration of existing blood vessels into the tumor vasculature), and vessel regression remodel the healthy vascular network into a tumor-specific vasculature. Integrative models, based on detailed experimental data and physical laws, implement, in silico, the complex interplay of molecular pathways, cell proliferation, migration, and death, tissue microenvironment, mechanical and hydrodynamic forces, and the fine structure of the host tissue vasculature. With the help of computer simulations high-precision information about blood flow patterns, interstitial fluid flow, drug distribution, oxygen and nutrient distribution can be obtained and a plethora of therapeutic protocols can be tested before clinical trials. This chapter provides an overview over the current status of computer simulations of vascular remodeling during tumor growth including interstitial fluid flow, drug delivery, and oxygen supply within the tumor. The model predictions are compared with experimental and clinical data and a number of longstanding physiological paradigms about tumor vasculature and intratumoral solute transport are critically scrutinized.

Cerebral venous thrombosis in a gentleman presenting with fever, convulsion and frontotemporal haemorrhages.

PubMed

Chan, K H; Cheung, R T F; Liu, W M; Mak, W; Ho, S L

2005-02-01

Cerebral venous thrombosis (CVT) is an uncommon but serious type of stroke. Thrombosis may involve the cortical or deep veins or the venous sinuses. The presenting clinical features are non-specific. We report a 48-year-old man with CVT who presented with fever, bitemporal throbbing headache, and generalised convulsion. Computed tomography (CT) of the brain revealed acute haemorrhages over right anterior frontal and posterior temporal regions with surrounding oedema and right anterior temporal subcortical oedema. The initial diagnosis was herpes simplex encephalitis. Absence of venous flow over the right transverse and sigmoid sinuses during the venous phase of digital subtraction angiography (DSA) revealed CVT. He was anti-coagulated for 6 months. An underlying cause of CVT was not detected. A high index of suspicion is required when risk factors of CVT are present. CT brain may be normal or showing non-specific findings. Magnetic resonance imaging plus venography, CT venography, or DSA is diagnostic.

Percutaneous bioprosthetic venous valve: a long-term study in sheep.

PubMed

Pavcnik, Dusan; Uchida, Barry T; Timmermans, Hans A; Corless, Christopher L; O'Hara, Michael; Toyota, Naoyuki; Moneta, Gregory L; Keller, Frederick S; Rösch, Josef

2002-03-01

A long-term evaluation of a new percutaneously placed bioprosthetic, bicuspid venous valve (BVV) consisting of a square stent and small intestinal submucosa (SIS) covering was performed in 12 sheep. Of 26 BVVs placed into the jugular veins, 25 exhibited good valve function on immediate venography and 22 on venograms obtained before the sheep were killed. Gross and histologic examination results demonstrated incorporation of remodeled and endothelialized SIS BVVs into the vein wall. Slight to moderate leaflet thickening was found mostly at their bases. Percutaneously placed SIS BVV is a promising one-way, competent valve that resists venous back-pressure while allowing forward flow.

Primary Sutureless Repair Using Biatrial Incision: Suture-And-Open Technique.

PubMed

Kim, Hyungtae; Sung, Si Chan; Choi, Kwang Ho; Lee, Hyoung Doo; Kim, Geena; Ko, Hoon

2018-06-08

We used a suture-and-open technique with a biatrial incision for primary sutureless repair of total anomalous pulmonary venous connection (TAPVC). With this technique, the common pulmonary venous sinus and its branching pulmonary veins are opened after completion of suturing of the left atrial incision to the pericardium around the common pulmonary venous sinus and its branching veins. The technique allows the primary sutureless repair of TAPVC to be done in a less bloody field under full-flow cardiopulmonary bypass. We have performed this technique in our recent 5 consecutive TAPVC patients without significant complications. Copyright © 2018. Published by Elsevier Inc.

Cortical venous disease severity in MELAS syndrome correlates with brain lesion development.

PubMed

Whitehead, M T; Wien, M; Lee, B; Bass, N; Gropman, A

2017-08-01

MELAS syndrome is a mitochondrial disorder typified by recurrent stroke-like episodes, seizures, and progressive brain injury. Abnormal mitochondria have been found in arterial walls implicating a vasculogenic etiology. We have observed abnormal cortical vein T2/FLAIR signal in MELAS patients, potentially representing wall thickening and sluggish flow. We sought to examine the relationship of hyperintense veins and brain lesions in MELAS. Imaging databases at two children's hospitals were searched for brain MRIs from MELAS patients. Artifact, sedated exams, and lack of 2D-T2/FLAIR sequences were exclusion criteria. Each exam was assigned a venous score based on number of T2/FLAIR hyperintense veins: 1 = <10, 2 = 10 to 20, 3 = >20. Cumulative brain lesions and venous score in MELAS and aged-matched normal exams were compared by Mann-Whitney test. A total of 106 exams from 14 unique MELAS patients (mean 16 ± 3 years) and 30 exams from normal aged-matched patients (mean 15 ± 3 years) were evaluated. Median venous score between MELAS and control patients significantly differed (3 versus 1; p < 0.001). In the MELAS group, venous score correlated with presence (median = 3) or absence (median = 1) of cumulative brain lesions. In all 8 MELAS patients who developed lesions, venous hyperintensity was present prior to, during, and after lesion onset. Venous score did not correlate with brain lesion acuity. Abnormal venous signal correlates with cumulative brain lesion severity in MELAS syndrome. Cortical venous stenosis, congestion, and venous ischemia may be mechanisms of brain injury. Identification of cortical venous pathology may aid in diagnosis and could be predictive of lesion development.

Modification of hemi-Fontan operation for patients with functional single ventricle and anomalous pulmonary venous connection to the superior vena cava: mid-term results†

PubMed Central

Ito, Hiroki; Murata, Masaya; Ide, Yujiro; Sugano, Mikio; Kanno, Kazuyoshi; Imai, Kenta; Ishido, Motonori; Fukuba, Ryohei; Sakamoto, Kisaburo

2016-01-01

OBJECTIVES Fontan candidates with mixed totally anomalous pulmonary venous connection often have postoperative pulmonary venous obstruction after cavopulmonary anastomosis. Because some pulmonary venous obstructions have no intimal hypertrophy at reoperation, we considered such pulmonary venous obstructions to be caused by 3D deformities arising from dissection or mobilization of the vessels, and hypothesized that keeping the pulmonary venous branches in a natural position could avoid such obstruction. Here, we evaluated a modified hemi-Fontan strategy consisting of minimal dissection with no division of vessels and patch separation between systemic and pulmonary venous flow. METHODS We retrospectively reviewed clinical records of infants with a functional single ventricle and supracardiac anomalous pulmonary venous connection who had undergone this procedure between 2002 and 2012. RESULTS Nine infants underwent this procedure (median age, 5.6 months; range 3.2–30), all with right atrial isomerism and several pulmonary venous branches directly and separately connecting to the superior vena cava. In 5 patients, all pulmonary veins drained into the superior vena cava; in 1, the right pulmonary veins drained into the superior vena cava and in 3, a pulmonary venous branch drained into the superior vena cava. The median follow-up was 6.9 years (0.8–13 years). Three patients underwent reoperation for postoperative pulmonary venous obstruction caused by intimal hypertrophy; however, we confirmed no pulmonary venous obstruction caused by 3D deformities on the pulmonary venous branches connecting separately to the superior vena cava. Although 2 patients were effectively relieved from pulmonary venous obstruction, 1 died due to recurrent pulmonary venous obstruction. There was no late death and no sinus-node dysfunction. Eight patients underwent successful Fontan operation and catheterization. The median interval from the Fontan operation to the latest catheterization was 3.7 years (0.9–3.7 years). The median arterial oxygen saturation was 94% (91–97%) and the central venous pressure was 12 mmHg (8–14 mmHg); no deficiency of pulmonary arteries and veins was noted. CONCLUSIONS For patients with functional single ventricle and anomalous pulmonary venous connections to the superior vena cava, our novel strategy of second-stage palliation could avoid postoperative pulmonary venous obstruction caused by 3D deformities, but may not eliminate pulmonary venous obstruction caused by intimal hypertrophy. PMID:26860898

Cardiovascular Pressures with Venous Gas Embolism and Decompression

NASA Technical Reports Server (NTRS)

Butler, B. D.; Robinson, R.; Sutton, T.; Kemper, G. B.

1995-01-01

Venous gas embolism (VGE) is reported with decompression to a decreased ambient pressure. With severe decompression, or in cases where an intracardiac septal defect (patent foramen ovale) exists, the venous bubbles can become arterialized and cause neurological decompression illness. Incidence rates of patent foramen ovale in the general population range from 25-34% and yet aviators, astronauts, and deepsea divers who have decompression-induced venous bubbles do not demonstrate neurological symptoms at these high rates. This apparent disparity may be attributable to the normal pressure gradient across the atria of the heart that must be reversed for there to be flow potency. We evaluated the effects of: venous gas embolism (0.025, 0.05 and 0.15 ml/ kg min for 180 min.) hyperbaric decompression; and hypobaric decompression on the pressure gradient across the left and right atria in anesthetized dogs with intact atrial septa. Left ventricular end-diastolic pressure was used as a measure of left atrial pressure. In a total of 92 experimental evaluations in 22 dogs, there were no reported reversals in the mean pressure gradient across the atria; a total of 3 transient reversals occurred during the peak pressure gradient changes. The reasons that decompression-induced venous bubbles do not consistently cause serious symptoms of decompression illness may be that the amount of venous gas does not always cause sufficient pressure reversal across a patent foramen ovale to cause arterialization of the venous bubbles.

Treatment of Post-SCI Hypotension

ClinicalTrials.gov

2018-02-15

Spinal Cord Injury; Autonomic Dysreflexia; Orthostatic Hypotension; Baroreceptor Integrity; Sympathetic Integrity; Vagal Integrity; Hypotension; Cerebral Blood Flow; Blood Pressure; Venous Occlusion Plethysmography

Journal of Special Operations Medicine. Volume 9, Edition 2, Spring 2009

DTIC Science & Technology

2009-01-01

patient. The most accessible veins for intra- venous catheterization include the cephalic vein on the thoracic limb (Figure 10), the saphenous vein on...threatening hypotension by restoring central blood vol- ume through enhancement of venous blood flow back to the heart with each inspiratory effort. HOW...examination of the latest advancements in medicine and the history of unconventional warfare medicine. Content: Content of this publication is not

Second diastolic pulmonary venous flow and isolated late diastolic mitral valve regurgitation in first-degree atrioventricular block.

PubMed

Leibundgut, Gregor; Bernheim, Alain M

2010-04-01

The authors report the case of a 77-year-old male patient with sinus rhythm and a first-degree atrioventricular (AV) block who was referred for echocardiographic follow-up 18 years after aortic valve replacement. Left ventricular systolic function as well as the function of the aortic prosthesis was normal. Systolic mitral regurgitation (MR) was virtually absent, but isolated late diastolic MR was detected by colour Doppler imaging. Coincidental to the occurrence of diastolic MR, a second late diastolic forward flow in the pulmonary veins was observed. Therefore, during the prolonged left atrial relaxation caused by first-degree AV block, the left atrial pressure drops below the pressure in both adjacent chambers in late diastole, resulting in both late diastolic MR and a second diastolic pulmonary venous forward flow.

Cerebral blood flow in patients with congestive heart failure treated with captopril.

PubMed

Paulson, O B; Jarden, J O; Godtfredsen, J; Vorstrup, S

1984-05-31

The effect of captopril on cerebral blood flow was studied in five patients with severe congestive heart failure and in five control subjects. Cerebral blood flow was measured by inhalation of 133xenon and registration of its uptake and washout from the brain by single photon emission computer tomography. In addition, cerebral (internal jugular) venous oxygen tension was determined in the controls. The measurements were made before and 15, 60, and 180 minutes after a single oral dose of captopril (6.25 mg in patients with congestive heart failure and 25 mg in controls). Despite a marked decrease in blood pressure, cerebral blood flow increased slightly in the patients with severe congestive heart failure. When a correction was applied to take account of a change in arterial carbon dioxide tension, however, cerebral blood flow was unchanged after captopril administration even in patients with the greatest decrease in blood pressure, in whom a decrease in cerebral blood flow might have been expected. In the controls, blood pressure was little affected by captopril, whereas a slight, but not statistically significant, decrease in cerebral blood flow was observed. The cerebral venous oxygen tension decreased concomitantly.

Reliability of muscle blood flow and oxygen consumption response from exercise using near-infrared spectroscopy.

PubMed

Lucero, Adam A; Addae, Gifty; Lawrence, Wayne; Neway, Beemnet; Credeur, Daniel P; Faulkner, James; Rowlands, David; Stoner, Lee

2018-01-01

What is the central question of this study? Continuous-wave near-infrared spectroscopy, coupled with venous and arterial occlusions, offers an economical, non-invasive alternative to measuring skeletal muscle blood flow and oxygen consumption, but its reliability during exercise has not been established. What is the main finding and its importance? Continuous-wave near-infrared spectroscopy devices can reliably assess local skeletal muscle blood flow and oxygen consumption from the vastus lateralis in healthy, physically active adults. The patterns of response exhibited during exercise of varying intensity agree with other published results using similar methodologies, meriting potential applications in clinical diagnosis and therapeutic assessment. Near-infrared spectroscopy (NIRS), coupled with rapid venous and arterial occlusions, can be used for the non-invasive estimation of resting local skeletal muscle blood flow (mBF) and oxygen consumption (mV̇O2), respectively. However, the day-to-day reliability of mBF and mV̇O2 responses to stressors such as incremental dynamic exercise has not been established. The aim of this study was to determine the reliability of NIRS-derived mBF and mV̇O2 responses from incremental dynamic exercise. Measurements of mBF and mV̇O2 were collected in the vastus lateralis of 12 healthy, physically active adults [seven men and five women; 25 (SD 6) years old] during three non-consecutive visits within 10 days. After 10 min rest, participants performed 3 min of rhythmic isotonic knee extension (one extension every 4 s) at 5, 10, 15, 20, 25 and 30% of maximal voluntary contraction (MVC), before four venous occlusions and then two arterial occlusions. The mBF and mV̇O2 increased proportionally with intensity [from 0.55 to 7.68 ml min -1  (100 ml) -1 and from 0.05 to 1.86 ml O 2  min -1  (100 g) -1 , respectively] up to 25% MVC, where they began to plateau at 30% MVC. Moreover, an mBF/mV̇O2 muscle oxygen consumption ratio of ∼5 was consistent for all exercise stages. The intraclass correlation coefficient for mBF indicated high to very high reliability for 10-30% MVC (0.82-0.9). There was very high reliability for mV̇O2 across all exercise stages (intraclass correlation coefficient 0.91-0.96). In conclusion, NIRS can reliably assess muscle blood flow and oxygen consumption responses to low- to moderate-intensity exercise, meriting potential applications in clinical diagnosis and therapeutic assessment. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Current concepts in repair of extremity venous injury.

PubMed

Williams, Timothy K; Clouse, W Darrin

2016-04-01

Extremity venous injury management remains controversial. The purpose of this communication is to offer perspective as well as experiential and technical insight into extremity venous injury repair. Available literature is reviewed and discussed. Historical context is provided. Indication, the decision process for repair, including technical conduct, is delineated. In particular, the authors' experiences in both civilian and wartime injury are used for perspective. Extremity venous injury repair was championed within data from the Vietnam Vascular Registry. However, patterns of extremity venous injury differ between combat and civilian settings. Since Vietnam, civilian descriptive series opine the benefits and potential complications associated with both venous injury repair and ligation. These surround extremity edema, chronic venous insufficiency, thromboembolism, and limb loss. Whereas no clear superiority in either approach has been identified to date, there appears to be no increased risk of pulmonary embolism or chronic venous changes with repair. Newer data from the wars in Iraq and Afghanistan and meta-analysis have reinforced this and also have suggested limb salvage benefit for extremity venous repair in combined arterial and venous injuries in modern settings. The patient's physiologic state and associated injury drive five triage categories suggesting vein injury management. Vein repair thrombosis occurs in a significant proportion, yet many recanalize and possibly have a positive impact on limb venous return. Further, early decompression favors reduced blood loss, acute edema, and inflammation, supporting collateral development. Large soft tissue injury minimizing collateral capacity increases the importance of repair. Constructs of repair are varied with modest differences in patency. Venous shunting is feasible, but specific roles remain nebulous. An aggressive posture toward extremity venous injury repair seems justified today because of the likely role in reducing venous hypertensive sequelae as well as a potential role in limb salvage. Appropriate triage selection for extremity vein repair is essential. Copyright © 2016 Society for Vascular Surgery. All rights reserved.

Cranial dural arteriovenous shunts. Part 4. Clinical presentation of the shunts with leptomeningeal venous drainage.

PubMed

Baltsavias, Gerasimos; Spiessberger, Alex; Hothorn, Torsten; Valavanis, Anton

2015-04-01

Cranial dural arteriovenous fistulae have been classified into high- and low-risk lesions mainly based on the pattern of venous drainage. Those with leptomeningeal venous drainage carry a higher risk of an aggressive clinical presentation. Recently, it has been proposed that the clinical presentation should be considered as an additional independent factor determining the clinical course of these lesions. However, dural shunts with leptomeningeal venous drainage include a very wide spectrum of inhomogeneous lesions. In the current study, we correlated the clinical presentation of 107 consecutive patients harboring cranial dural arteriovenous shunts with leptomeningeal venous drainage, with their distinct anatomic and angiographic features categorized into eight groups based on the "DES" (Directness and Exclusivity of leptomeningeal venous drainage and features of venous Strain) concept. We found that among these groups, there are significant angioarchitectural differences, which are reflected by considerable differences in clinical presentation. Leptomeningeal venous drainage of dural sinus shunts that is neither direct nor exclusive and without venous strain manifested only benign symptoms (aggressive presentation 0%). On the other end of the spectrum, the bridging vein shunts with direct and exclusive leptomeningeal venous drainage and venous strain are expected to present aggressive symptoms almost always and most likely with bleeding (aggressive presentation 91.5%). Important aspects of the above correlations are discussed. Therefore, the consideration of leptomeningeal venous drainage alone, for prediction of the clinical presentation of these shunts appears insufficient. Angiographic analysis based on the above concept, offers the possibility to distinguish the higher- from the lower-risk types of leptomeningeal venous drainage. In this context, consideration of the clinical presentation as an additional independent factor for the prediction of their clinical course seems superfluous and possibly misleading. Topography is connected to the clinical presentation of the dural shunts inasmuch as the former determines the venous anatomy and the angioarchitectural features of the lesions.

Umbilical venous catheters placement evaluation on frontal radiogram: application of a simplified flow-chart for radiology residents.

PubMed

Salerno, Sergio; Tudisca, Chiara; Murmura, Elena; Matranga, Domenica; La Tona, Giuseppe; Lo Re, Giuseppe; Lo Casto, Antonio

2017-05-01

Umbilical Venous Catheter (UVC) are commonly used in neonatal period; they can be not correctly positioned and could be associated with complications. The purpose of this article is to suggest a flow-chart to evaluate the placement of UVC, testing it in young radiologists-in-training. We developed a simple flow-chart to asses, steps by step, UVC placement considering its course and tip location (ideally placed in the atriocaval junction). We tested the flow-chart impact asking to 20 residents to evaluate the placement of 10 UVC before and after they familiarized with the flow-chart and the anatomical findings of a newborn. The agreement among the 20 students was evaluated too. The number of correct characterizations was different due to the administration of the flow-chart. One hundred and six correct UVC assessments at the beginning switched to 196 after the administration of the flow-chart (p = 0.0001). The observed agreement among the twenty radiology residents was statistically significant, both before (kappa = 0.41, p < 0.001) and after (kappa = 0.37, p < 0.001) the flow-chart administration. The developed flow-chart demonstrated to be useful in increasing residents performance in UVC placement assessment.

Characterisation of human induced pluripotent stem cell-derived endothelial cells under shear stress using an easy-to-use microfluidic cell culture system.

PubMed

Ohtani-Kaneko, Rsituko; Sato, Kenjiro; Tsutiya, Atsuhiro; Nakagawa, Yuka; Hashizume, Kazutoshi; Tazawa, Hidekatsu

2017-10-09

Induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) can contribute to elucidating the pathogenesis of heart and vascular diseases and developing their treatments. Their precise characteristics in fluid flow however remain unclear. Therefore, the aim of the present study is to characterise these features. We cultured three types of ECs in a microfluidic culture system: commercially available human iPS-ECs, human umbilical vein endothelial cells (HUVECs) and human umbilical artery endothelial cells (HUAECs). We then examined the mRNA expression levels of endothelial marker gene cluster of differentiation 31 (CD31), fit-related receptor tyrosine kinase (Flk-1), and the smooth muscle marker gene smooth muscle alpha-actin, and investigated changes in plasminogen activator inhibitor-1 (PAI-1) secretion and intracellular F-actin arrangement following heat stress. We also compared expressions of the arterial and venous marker genes ephrinB2 and EphB4, and the endothelial gap junction genes connexin (Cx) 37, 40, and 43 under fluidic shear stress to determine their arterial or venous characteristics. We found that iPS-ECs had similar endothelial marker gene expressions and exhibited similar increases in PAI-1 secretion under heat stress as HUVECs and HUAECs. In addition, F-actin arrangement in iPSC-ECs also responded to heat stress, as previously reported. However, they had different expression patterns of arterial and venous marker genes and Cx genes under different fluidic shear stress levels, showing that iPSC-ECs exhibit different characteristics from arterial and venous ECs. This microfluidic culture system equipped with variable shear stress control will provide an easy-to-use assay tool to examine characteristics of iPS-ECs generated by different protocols in various laboratories and contribute to basic and applied biomedical researches on iPS-ECs.

Proposal for Prevention or Alleviation of Protein/Lymph-Losing Enteropathy (PLE/LLE) After Fontan Circulation Treatment of Univentricular Hearts: Restoration of Lymph Balance With a "Lymphatic Right-to-Left Shunt."

PubMed

James, H; Witte, M H; Bernas, M; Barber, B

2016-09-01

In Fontan circulations created for univentricular hearts, systemic venous return is diverted to the lungs before returning to the heart. The Total Cavopulmonary Connection (TCPC) is often the preferred surgical procedure whereby a 4-way anastomosis is created with inflow from the superior vena cava (SVC) and inferior vena cava (IVC) and outflow to the right and left branches of the pulmonary artery. In this arrangement, the systemic venous pressure must be elevated sufficiently to perfuse the lungs passively without the normal boost of the right ventricle. Hence, unlike surgical corrections for other congenital heart conditions, the systemic venous pressures in a Fontan circuit must be elevated to make the circulation work. It is proposed here that the incidence of PLE/LLE is directly related to elevated venous and lymphatic pressures, which cause leakage of proteins/lymph into the gastrointestinal tract (GIT) and expulsion from the body. It is commonly held that elevated venous pressures are relatively better tolerated in the upper body, but much less so in the heptatosplanchnic circulation and the lower body. It is also well established that elevated venous pressure increases lymph formation, most of which is produced in the hepatosplanchnic region (liver and intestine). It is further argued here that the increase in lymph filling pressure arising from the higher lymph flow, in association with the backpressure exerted by elevated venous pressure at the main drainage point into the venous system, results in a substantial increase in pressure in the thoracic duct. This pressure is transmitted back to the intestinal lymphatics, causing dilatation with lacteal rupture and protein or bulk lymph leakage into the intestine. We propose in this paper a new approach, based on experimental evidence, to prevent and/or alleviate this condition by draining or redirecting the thoracic duct (or, alternatively, a more localized intestinal lymphatic vessel) into one of the pulmonary veins or the left atrium, which are typically at near-normal pressure in a Fontan circulation. This “lymphatic-venous right-to-left” shunt maneuver would significantly reduce the venous backpressure on the lymphatics as well as improve lymph circulation, resulting in a decrease in the intestinal lymphatic pressure and thereby prevent or alleviate protein/lymph loss, i.e. lymph balance would be restored. Moreover, the greatly facilitated lymphatic flow would encourage further capillary filtration to relieve excessive venous pressure in the hepatosplanchnic region and protect the liver and kidneys. This paper is intended as a discussion document for elicitation of comments on the soundness and viability of this proposal as well as on technical challenges and steps to explore and advance it.

Hematocrit Measurement with R2* and Quantitative Susceptibility Mapping in Postmortem Brain.

PubMed

Walsh, A J; Sun, H; Emery, D J; Wilman, A H

2018-05-24

Noninvasive venous oxygenation quantification with MR imaging will improve the neurophysiologic investigation and the understanding of the pathophysiology in neurologic diseases. Available MR imaging methods are limited by sensitivity to flow and often require assumptions of the hematocrit level. In situ postmortem imaging enables evaluation of methods in a fully deoxygenated environment without flow artifacts, allowing direct calculation of hematocrit. This study compares 2 venous oxygenation quantification methods in in situ postmortem subjects. Transverse relaxation (R2*) mapping and quantitative susceptibility mapping were performed on a whole-body 4.7T MR imaging system. Intravenous measurements in major draining intracranial veins were compared between the 2 methods in 3 postmortem subjects. The quantitative susceptibility mapping technique was also applied in 10 healthy control subjects and compared with reference venous oxygenation values. In 2 early postmortem subjects, R2* mapping and quantitative susceptibility mapping measurements within intracranial veins had a significant and strong correlation ( R 2 = 0.805, P = .004 and R 2 = 0.836, P = .02). Higher R2* and susceptibility values were consistently demonstrated within gravitationally dependent venous segments during the early postmortem period. Hematocrit ranged from 0.102 to 0.580 in postmortem subjects, with R2* and susceptibility as large as 291 seconds -1 and 1.75 ppm, respectively. Measurements of R2* and quantitative susceptibility mapping within large intracranial draining veins have a high correlation in early postmortem subjects. This study supports the use of quantitative susceptibility mapping for evaluation of in vivo venous oxygenation and postmortem hematocrit concentrations. © 2018 by American Journal of Neuroradiology.

Extrahepatic portosystemic shunt in congenital absence of the portal vein depicted by time-resolved contrast-enhanced MR angiography.

PubMed

Goo, Hyun Woo

2007-07-01

Congenital absence of the portal vein is a rare malformation in which mesenteric and splenic venous flow bypasses the liver and drains into various sites in the systemic venous system via an extrahepatic portosystemic shunt. In an 11-year-old girl with congenital absence of the portal vein, the detailed anatomy of the extrahepatic portosystemic shunt is demonstrated by time-resolved contrast-enhanced MR angiography.

Venous sinus occlusive disease: MR findings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuh, W.T.C.; Simonson, T.M.; Tali, E.T.

1994-02-01

To study MR patterns of venous sinus occlusive disease and to relate them to the underlying pathophysiology by comparing the appearance and pathophysiologic features of venous sinus occlusive disease with those of arterial ischemic disease. The clinical data and MR examinations of 26 patients with venous sinus occlusive disease were retrospectively reviewed with special attention to mass effect, hemorrhage, and T2-weighted image abnormalities as well as to abnormal parenchymal, venous, or arterial enhancement after intravenous gadopentetate dimeglumine administration. Follow-up studies when available were evaluated for atrophy, infraction, chronic mass effect, and hemorrhage. Mass effect was present in 25 of 26more » patients. Eleven of the 26 had mass effect without abnormal signal on T2-weighted images. Fifteen patients had abnormal signal on T2-weighted images, but this was much less extensive than the degree of brain swelling in all cases. No patient showed abnormal parenchymal or arterial enhancement. Abnormal venous enhancement was seen in 10 of 13 patients who had contrast-enhanced studies. Intraparenchymal hemorrhage was seen in nine patients with high signal on T2-weighted images predominantly peripheral to the hematoma in eight. Three overall MR patterns were observed in acute sinus thrombosis: (1) mass effect without associated abnormal signal on T2-weighted images, (2) mass effect with associated abnormal signal on T2-weighted images and/or ventricular dilatation that may be reversible, and (3) intraparenchymal hematoma with surrounding edema. MR findings of venus sinus occlusive disease are different from those of arterial ischemia and may reflect different underlying pathophysiology. In venous sinus occlusive disease, the breakdown of the blood-brain barrier (vasogenic edema and abnormal parenchymal enhancement) does not always occur, and brain swelling can persist up to 2 years with or without abnormal signal on T2-weighted images. 34 refs., 5 figs.« less

Patterns of anomalous pulmonary venous drainage.

PubMed

Snellen, H A; van Ingen, H C; Hoefsmit, E C

1968-07-01

All of our cases of abnormal pulmonary venous connections collected to the middle of 1965 and verified at surgery or autopsy have been reviewed by means of diagrams and tabulations, using a specially devised code to facilitate the survey. The material consisted of 52 autopsy cases (half of them obtained after surgery) and the cases of 72 patients who survived operation. The postmortem group was much younger than the surgical group and differed also from the latter by showing male preponderance as well as relatively many instances of total abnormal pulmonary venous connection and frequently associated cardiac anomalies. Partial anomalous connection of right pulmonary veins was 10 times more frequent than that of the left pulmonary veins. This was caused by (1) the frequent drainage of some of the right pulmonary veins into the junctional area between right atrium and superior vena cava in the presence of normal left pulmonary veins, and (2) the complete absence of isolated left pulmonary venous connection to the right atrium. Abnormal connection of solitary pulmonary veins was always effected to the most proximal venous structure among the four possible ones which are derived from the main embryonic channels (superior vena cava and inferior vena cava on the right side, and left superior vena cava and coronary sinus on the left side). Common pulmonary veins from one lung also drained in accordance with this proximity rule, if this may be taken to apply also to the drainage of right pulmonary veins into the right atrium. The one exception in our material was the drainage of all right pulmonary veins into the portal venous system. Total abnormal pulmonary venous connection may be found with all structures mentioned, but most frequently with the left superior vena cava, or coronary sinus, or both, usually by way of a common pulmonary vein. In a few cases however, drainage into different sites, all of them abnormal, did occur. Then again the proximity rule seemed to apply. A tentative embryological explanation is given for the patterns described.

Venous and Arterial Thromboses: Two Sides of the Same Coin?

PubMed

Lippi, Giuseppe; Favaloro, Emmanuel J

2018-04-01

Arterial and venous thromboses are sustained by development of intraluminal thrombi, respectively, within the venous and arterial systems. The composition and structure of arterial and venous thrombi have been historically considered as being very different. Arterial thrombi (conventionally defined as "white") have been traditionally proposed to be composed mainly of fibrin and platelet aggregates, whilst venous thrombi (conventionally defined as "red") have been proposed as mostly being enriched in fibrin and erythrocytes. This archaic dichotomy seems ever more questionable, since it barely reflects the pathophysiology of thrombus formation in vivo. Both types of thrombi are actually composed of a complex fibrin network but, importantly, also contain essentially the same blood-borne cells (i.e., red blood cells, leukocytes, and platelets), and it is only the relative content of these individual elements that differ between venous and arterial clots or, otherwise, between thrombi generated under different conditions of blood flow and shear stress. Convincing evidence now suggests that either white or red intracoronary thrombi may be present in patients with myocardial infarction and, even more importantly, red thrombi may be more prone to distal embolization during percutaneous coronary intervention than those with lower content of erythrocytes. Conversely, it is now accepted that components traditionally considered to be involved "only" in arterial thrombosis are also represented in venous thrombosis. Thus, platelets comprise important components of venous clots, although they may be present in lower amounts here than in arterial thrombi, and von Willebrand factor is also represented in both arterial and venous thrombi. Of importance, such evidence thus supports the concept that adjunctive treatment normally associated to prevention of arterial thrombosis (e.g., aspirin) may have a role also in prevention and treatment of venous thrombosis. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Clinical and Ultrasonographic Evaluation of Lower-extremity Vein Thrombosis in Behcet Syndrome: An Observational Study.

PubMed

Seyahi, Emire; Cakmak, Osman Serdal; Tutar, Burcin; Arslan, Caner; Dikici, Atilla Suleyman; Sut, Necdet; Kantarci, Fatih; Tuzun, Hasan; Melikoglu, Melike; Yazici, Hasan

2015-11-01

Vascular involvement can be seen in up to 40% of patients with Behcet syndrome (BS), the lower-extremity vein thrombosis (LEVT) being the most common type. The aim of the current study was to compare venous Doppler findings and clinical features between BS patients with LEVT and control patients diagnosed as having LEVT due to other causes.All consecutive 78 patients (71 men, 7 women; mean age 38.6 ± 10.3 years) with LEVT due to BS and 50 control patients (29 men, 21 women; mean age 42.0 ± 12.5 years) who had LEVT due to other causes, or idiopathic, were studied with the help of a Doppler ultrasonography after a detailed clinical examination. Patterns of venous disease were identified by cluster analyses. Clinical features of chronic venous disease were assessed using 2 classification systems. Venous claudication was also assessed.Patients with BS were more likely to be men, had significantly earlier age of onset of thrombosis, and were treated mainly with immunosuppressives and less frequently with anticoagulants. Furthermore, they had significantly more bilateral involvement, less complete recanalization, and more frequent collateral formation. While control patients had a disorganized pattern of venous involvement, BS patients had a contiguous and symmetric pattern, involving all deep and superficial veins of the lower extremities, with less affinity for crural veins. Clinical assessment, as measured by the 2 classification systems, also indicated a more severe disease among the BS patients. In line, 51% of the BS patients suffered from severe post-thrombotic syndrome (PTS) and 32% from venous claudication, whereas these were present in 8% and 12%, respectively, among the controls. Among BS patients, a longer duration of thrombosis, bilateral femoral vein involvement, and using no anticoagulation along with immunosuppressive treatment when first diagnosed were found to be associated independently with severe PTS.Lower-extremity vein thrombosis associated with BS, when compared to LEVT due to other causes, had distinctive demographic and ultrasonographic characteristics, and had clinically a more severe disease course.

Clinical and Ultrasonographic Evaluation of Lower-extremity Vein Thrombosis in Behcet Syndrome

PubMed Central

Seyahi, Emire; Cakmak, Osman Serdal; Tutar, Burcin; Arslan, Caner; Dikici, Atilla Suleyman; Sut, Necdet; Kantarci, Fatih; Tuzun, Hasan; Melikoglu, Melike; Yazici, Hasan

2015-01-01

Abstract Vascular involvement can be seen in up to 40% of patients with Behcet syndrome (BS), the lower-extremity vein thrombosis (LEVT) being the most common type. The aim of the current study was to compare venous Doppler findings and clinical features between BS patients with LEVT and control patients diagnosed as having LEVT due to other causes. All consecutive 78 patients (71 men, 7 women; mean age 38.6 ± 10.3 years) with LEVT due to BS and 50 control patients (29 men, 21 women; mean age 42.0 ± 12.5 years) who had LEVT due to other causes, or idiopathic, were studied with the help of a Doppler ultrasonography after a detailed clinical examination. Patterns of venous disease were identified by cluster analyses. Clinical features of chronic venous disease were assessed using 2 classification systems. Venous claudication was also assessed. Patients with BS were more likely to be men, had significantly earlier age of onset of thrombosis, and were treated mainly with immunosuppressives and less frequently with anticoagulants. Furthermore, they had significantly more bilateral involvement, less complete recanalization, and more frequent collateral formation. While control patients had a disorganized pattern of venous involvement, BS patients had a contiguous and symmetric pattern, involving all deep and superficial veins of the lower extremities, with less affinity for crural veins. Clinical assessment, as measured by the 2 classification systems, also indicated a more severe disease among the BS patients. In line, 51% of the BS patients suffered from severe post-thrombotic syndrome (PTS) and 32% from venous claudication, whereas these were present in 8% and 12%, respectively, among the controls. Among BS patients, a longer duration of thrombosis, bilateral femoral vein involvement, and using no anticoagulation along with immunosuppressive treatment when first diagnosed were found to be associated independently with severe PTS. Lower-extremity vein thrombosis associated with BS, when compared to LEVT due to other causes, had distinctive demographic and ultrasonographic characteristics, and had clinically a more severe disease course. PMID:26554787

Improving patency of coronary conduits "valveless" veins and/or arterial grafts.

PubMed

Lajos, Thomas Z; Robicsek, Francis; Thubrikar, Mano; Urschel, Harold

2007-01-01

Veins used for coronary artery bypass operation have a well-documented limited long-term patency. Internal thoracic artery (ITA) grafts have shown exceptional "durability." Assumptions were made that other arterial conduits have similar characteristics. The purpose of this article is to compare different conduits long-term patency including saphenous veins to other available arterial conduits: inferior epigastric artery (IE), right gastroepiploic artery (RGEA), and radial artery (RA). Recent studies have shown that radial artery bypasses have lower patency rate than saphenous veins. Flow patterns, physiological flow characteristics are reviewed including native vessel disease and area of myocardium supplied. In the case of venous bypasses, the primary culprit of failure seemed to be the quality of the vein itself and the reverse venous valves in the conduit resulting in: (a) trapping-hypertension, (b) thrombosis, (c) turbulence, (d) intimal damage, (e) mismatching in size. Clinical follow-up of our patients up to 8 to 11 years (average 8.9 years) have proved the superior characteristics of the so-called "good veins." In a retrospective study of 436 patients sequential, valveless veins patency was 88.6% versus 72% of reversed valvular segments (p < 0.01). Patients' survival seemed to be significantly improved if these veins were combined with ITA grafts. Patients' survival with one valveless limb HS + ITA was 78% versus HS + SV 52% (p < or = 0.0017) and HS + ITA versus HS + ITA + SV (p < 0.0057). Selective decision-making of the surgeon at the time of the operation is required to choose the best conduit to be able to perform the best operation with the best long-term result.

Effects of cell salvage on erythrocyte 2,3-disphosphoglycerate and G-6-PD levels and phosphatidylserine expression.

PubMed

Che, J; Tian, M; Ding, G; Huai, Q; Dong, P; Li, Y; Li, S

2013-08-01

The aim of this study was to investigate the contribution of the perioperative cell salvage process to the changes in erythrocyte 2,3-disphosphoglycerate (2,3-DPG) and glucose-6-phosphate dehydrogenase (G-6-PD) levels and phosphatidylserine (PS) expression using a self-control study comparing washed blood with venous blood. Thirty patients undergoing elective heart and blood vessel surgery were enrolled. Blood was collected and processed using a Fresenius continuous autotransfusion system device. 2,3-DPG and G-6-PD activities, as well as PS expression, from both venous and washed red blood cells (RBC) were measured. We also compared these indicators among washed RBC at 6 h, washed RBC at 0 h, and venous RBC. 2,3-DPG and G-6-PD activities in washed blood at 0 h were significantly higher than in venous RBC (2,3-DPG, venous vs. washed blood P < 0.05; G-6-PD, venous vs. washed blood P < 0.05). Flow cytometry results showed no differences between venous blood and washed RBC at 0 h (n = 23, P > 0.05). 2,3-DPG activity in washed RBC that were allowed to stand for 6 h decreased compared with that in venous blood (venous vs. washed blood at 6 h P < 0.01), whereas no significant difference was observed in G-6-PD activity (venous. vs. washed blood at 6 h P > 0.05). Compared with venous RBC, washed RBC from intraoperative cell salvage exhibited good oxygen-carrying and antioxidant capacities. However, the oxygen-carrying capacity of washed RBC that were allowed to stand for 6 h was not as good as that of venous RBC. Thus, we suggest that washed RBC that were left to stand for more than 6 h should not be reinfused. © 2012 John Wiley & Sons Ltd.

Intermittent KoldBlue cryotherapy of 3x10 min changes mid-portion Achilles tendon microcirculation.

PubMed

Knobloch, Karsten; Grasemann, Ruth; Spies, Marcus; Vogt, Peter M

2007-06-01

Neovascularisation and microcirculatory changes have been reported in Achilles tendinopathy. Cryotherapy and compression, as part of a rest, ice, compression and elevation regimen, are shown to decrease pain and improve function. However, the microcirculatory changes following a given dosage of cryotherapy on mid-portion Achilles tendon remain unclear. Prospective clinical cohort study, level of evidence 2. 30 people (12 males, 33 (SD 12) years, body mass index 25.6 (5.3) kg/m2) were included in the cohort. 3x10 min KoldBlue ankle-cooling bandages were applied and microcirculation of Achilles tendon mid-portion was real-time and continuously assessed using a laser-Doppler-spectrophotometry system (O2C, Germany). Superficial capillary blood flow was reduced from 42 to 6, 5 and 3 relative units (rU) in the first, second and third cryotherapy periods, respectively (-65%, p = 0.001), with no significant capillary hyperaemia. Deep capillary tendon blood flow was reduced from 180 to 82, 53 and 52 rU (-71%, p = 0.001) within 6-9 min of application without hyperaemia. Superficial tendon oxygen saturation dropped significantly from 43% to 26%, 18% and 11% (p = 0.001) after repetitive cryotherapy, with persisting increase of tendon oxygenation during rewarming (51%, 49% and 54%, p = 0.077) up to 27% of the baseline level. At 8 mm tendon depth, cryotherapy preserved local oxygenation. Relative postcapillary venous tendon filling pressures were favourably reduced from 41 (11) to 31, 28 and 26 rU (-36%, p = 0.001) superficially and from 56 (11) to 45, 46 and 48 rU (-18%, p = 0.001) in deep capillary blood flow during cryotherapy, facilitating capillary venous clearance. Intermittent cryotherapy of 3x10 min significantly decreases local Achilles tendon mid-portion capillary blood flow by 71%. Within 2 min of rewarming, tendon oxygen saturation is re-established following cryotherapy. Postcapillary venous filling pressures are reduced during cryotherapy, favouring capillary venous outflow of the healthy Achilles tendon.

Venous haemodynamics of Jet Impulse Technology within a lower limb fibreglass cast: a randomized controlled trial.

PubMed

Braithwaite, Irene; Mackintosh, Stephen; Buchanan, Samantha; Schwarzenlander, Kerstin; De Ruyter, Bernadette

2017-02-01

We investigated popliteal venous haemodynamics of the VenaJet Jet Impulse Technology system within a below-knee fibreglass cast. Randomized controlled trial. Twenty-four healthy participants aged 18-54 had both feet placed within the Jet Impulse Technology system and were randomised for one or other leg to be within a below-knee fibreglass cast. Pacific Radiology, Lower Hutt, Wellington. The primary outcome variable was peak systolic velocity (cm/s) compared between legs with and without the cast at 60 min (after 10 min Jet Impulse Technology activation), using a mixed linear model and a non-inferiority bound of 4.8 cm/s. Secondary outcome variables were the difference in peak systolic velocity between the casted limb and the non-casted limb at baseline and 40 min after casting, and the difference in mean flow velocity (cm/s), vein diameter (mm), and total volume flow (L/min) between the casted limb and the non-casted limb at baseline, 40 and 60 min. The mean (standard deviation) peak systolic velocity was 4.6(1.5), 4.8(1.1), 28.8(16.1), and 4.3(1.2), 4.8(1.4) and 29.3(19.0) cm/s at baseline, 40 and 60 min in the casted and non-casted leg, respectively. The difference (95% confidence interval) between cast and no-cast at 60 min was -0.8 (-6.5 to 4.9) cm/s, P  = 0.78. The peak systolic velocity, flow velocity and total volume flow at 40 min were not statistically significantly different from baseline for both casted and non-casted limb. In healthy volunteers, the popliteal venous haemodynamics of the Jet Impulse Technology system was similar between the legs with and without a below-knee fibreglass cast. In-cast Jet Impulse Technology may provide a non-pharmacological option for venous thromboembolism prophylaxis for lower-limb cast-immobility.

Anatomical considerations of percutaneous transvenous mitral annuloplasty: a novel procedure for treatment of functional mitral regurgitation.

PubMed

Mehra, Lalit; Raheja, Shashi; Agarwal, Sneh; Rani, Yashoda; Kaur, Kulwinder; Tuli, Anita

2016-03-01

Percutaneous transvenous mitral annuloplasty (PTMA) has evolved as a latest procedure for the treatment of functional mitral regurgitation. It reduces mitral valve annulus (MVA) size and increases valve leaflet coaptation via compression of coronary sinus (CS). Anatomical considerations for this procedure were elucidated in the present study. In 40 formalin fixed adult cadaveric human hearts, relation of the venous channel formed by CS and great cardiac vein (GCV) to MVA and the adjacent arteries was described, at 6 points by making longitudinal sections perpendicular to the plane of MVA, numbered 1-6 starting from CS ostium. CS/GCV formed a semicircular venous channel on the atrial side of MVA. Based on the distance of CS/GCV from MVA, two patterns were identified. In 37 hearts, the venous channel at point 2 was widely separated from the MVA compared to the two ends and in three hearts a nonconsistent pattern was observed. GCV crossed circumflex artery superficially. GCV or CS crossed the left marginal artery and ventricular branches of circumflex artery superficially in 17 and 23 hearts, respectively. As the venous channel was related more to the left atrial wall, PTMA devices probably exert an indirect traction on MVA. The arteries crossing deep to the venous channel may be compressed by PTMA device leading to myocardial ischemia. Knowledge of the spatial relations of MVA and a preoperative and postoperative angiogram may help to reduce such complications during PTMA.

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

PubMed Central

Javid Mahmoudzadeh Akherat, S. M.; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-01-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain. PMID:28249082

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

PubMed

Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-04-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain.

CCSVI and MS: no meaning, no fact.

PubMed

Baracchini, Claudio; Atzori, Matteo; Gallo, Paolo

2013-03-01

A condition called "chronic cerebrospinal venous insufficiency" (CCSVI) has been postulated to play a role in the pathogenesis of multiple sclerosis (MS). This hypothesis implies that a complex pattern of extracranial venous stenosis determines a venous reflux into the brain of MS patients, followed by increased intravenous pressure, blood-brain barrier breakdown and iron deposition into the brain parenchyma, thus triggering a local inflammatory response. In this review, we critically analyze the scientific basis of CCSVI, the current literature on the relationship between CCSVI and MS, as well as the ultrasound methodology that has been claimed to provide evidence of impaired cerebral venous drainage. We show that no piece of the CCSVI theory has a solid supportive scientific evidence. The CCSVI appears to be a rather alien condition and its existence should be definitely questioned. Finally, no proven (i.e., based on strict scientific methodology and on the rules of evidence-based medicine) therapeutic effect of the "liberation" procedure (unblocking the extracranial venous obstruction using angioplasty) has been shown up to date.

Surgical resection of large encephalocele: a report of two cases and consideration of resectability based on developmental morphology.

PubMed

Ohba, Hideo; Yamaguchi, Satoshi; Sadatomo, Takashi; Takeda, Masaaki; Kolakshyapati, Manish; Kurisu, Kaoru

2017-03-01

The first-line treatment of encephalocele is reduction of herniated structures. Large irreducible encephalocele entails resection of the lesion. In such case, it is essential to ascertain preoperatively if the herniated structure encloses critical venous drainage. Two cases of encephalocele presenting with large occipital mass underwent magnetic resonance (MR) imaging. In first case, the skin mass enclosed the broad space containing cerebrospinal fluid and a part of occipital lobe and cerebellum. The second case had occipital mass harboring a large portion of cerebrum enclosing dilated ventricular space. Both cases had common venous anomalies such as split superior sagittal sinus and high-positioned torcular herophili. They underwent resection of encephalocele without subsequent venous congestion. We could explain the pattern of venous anomalies in encephalocele based on normal developmental theory. Developmental theory connotes that major dural sinuses cannot herniate into the sac of encephalocele. Irrespective to its size, encephalocele can be resected safely at the neck without subsequent venous congestion.

Surgical implications of portal venous system malformation

PubMed Central

Marks, Charles

1974-01-01

The significance of congenital abnormalities in predisposing to portal hypertension and variceal haemorrhage needs to be remembered when these effects manifest in childhood, as portal venography will permit elucidation of the complicated congenital developmental abnormalities underlying the pathological condition and permit rational surgical amelioration. In the presence of portal hypertension the development of a collateral venous circulation may be represented by a hepatopetal or hepatofugal circulatory pattern and will closely parallel the developmental areas where portal and systemic venous circulations meet, being representative of the embryological anastomosis between the vitelloumbilical system and the posterior cardinal system of veins. ImagesFig. 3Fig. 5Fig. 6 PMID:4614690

Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project

NASA Technical Reports Server (NTRS)

Oliva-Buisson, Yvette J.

2014-01-01

Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.

Effects of acute hypoxia on cardiopulmonary responses to head-down tilt

NASA Technical Reports Server (NTRS)

Loeppky, J. A.; Luft, U. C.; Scotto, P.; Chick, T. W.

1990-01-01

Six male subjects were exposed on two separate occasions to simulated microgravity with 28 deg head-down tilt (HD) for 1 h with baseline followed by recovery at + 17 deg head-up. Pulmonary ventilation, gas exchange, spirometry, and central and cerebral blood flow characteristics were compared while breathing ambient air and reduced F(I)O2 equivalent to 14,828 ft. With hypoxia (HY), the increased tidal volume served to attenuate the drop in arterial saturation by reducing deadspace ventilation. Arterial and mixed venous PO2, values, estimated from peripheral venous samples and cardiac output (CO), were both maintained during HD in HY. Mixed venous PO2 was elevated by an increase in CO associated with a reduction in systemic resistance. Changes in spirometric indices during HD were not accentuated by HY, making the presence of interstitial edema unlikely. Cerebral flow and resistance showed minor reductions with HD. Tissue oxygenation and cardiopulmonary function were not notably effected by HD during HY, but a combination of these two stressors may predispose subjects to subsequent orthostatic intolerance during initial recovery.

Living donor liver transplantation for congenital absence of the portal vein.

PubMed

Sanada, Y; Mizuta, K; Kawano, Y; Egami, S; Hayashida, M; Wakiya, T; Mori, M; Hishikawa, S; Morishima, K; Fujiwara, T; Sakuma, Y; Hyodo, M; Yasuda, Y; Kobayashi, E; Kawarasaki, H

2009-12-01

The congenital absence of the portal vein (CAPV) is a rare venous malformation in which mesenteric venous blood drains directly into the systemic circulation. Liver transplantation (OLT) may be indicated for patients with symptomatic CAPV refractory to medical treatment, especially due to hyperammonemia, portosystemic encephalopathy, hepatopulmonary syndrome, or hepatic tumors. Because portal hypertension and collateral circulation do not occur with CAPV, significant splanchnic congestion may occur when the portocaval shunt is totally clamped during portal vein (PV) reconstruction in OLT. This phenomenon results in severe bowel edema and hemodynamic instability, which negatively impact the patient's condition and postoperative recovery. We have successfully reconstructed the PV in living donor liver transplantation (LDLT) using a venous interposition graft, which was anastomosed end-to-side to the portocaval shunt by a partial side-clamp, using a patent round ligament of the liver, which was anastomosed end-to-end to the graft PV with preservation of both the portal and caval blood flows. Owing to the differences in anatomy among patients, at LDLT for CAPV liver transplant surgeons should seek to preserve both portal and caval blood flows.

Systemic Venous Inflow to the Liver Allograft to Overcome Diffuse Splanchnic Venous Thrombosis

PubMed Central

Darius, Tom; Goffette, Pierre; Lerut, Jan

2015-01-01

Diffuse splanchnic venous thrombosis (DSVT), formerly defined as contraindication for liver transplantation (LT), is a serious challenge to the liver transplant surgeon. Portal vein arterialisation, cavoportal hemitransposition and renoportal anastomosis, and finally combined liver and small bowel transplantation are all possible alternatives to deal with this condition. Five patients with preoperatively confirmed extensive splanchnic venous thrombosis were transplanted using cavoportal hemitransposition (4x) and renoportal anastomosis (1x). Median follow-up was 58 months (range: 0,5 to 130 months). Two patients with previous radiation-induced peritoneal injury died, respectively, 18 days and 2 months after transplantation. The three other patients had excellent long-term survival, despite the fact that two of them needed a surgical reintervention for severe gastrointestinal bleeding. Extensive splanchnic venous thrombosis is no longer an absolute contraindication to liver transplantation. Although cavoportal hemitransposition and renoportal anastomosis undoubtedly are life-saving procedures allowing for ensuring adequate allograft portal flow, careful follow-up of these patients remains necessary as both methods are unable to completely eliminate the complications of (segmental) portal hypertension. PMID:26539214

Two cases of esophageal cancer with portal hypertension: esophagectomy with venous shunt procedure.

PubMed

Kato, T; Motohara, T; Kaneko, Y; Shikishima, H; Okushiba, S; Kondo, S; Kato, H

2001-01-01

We performed venous shunt procedure in the reconstruction of the esophagus after esophagectomy using the gastric tube in two cases of esophageal cancer with portal hypertension due to liver cirrhosis. In both cases, the short-term postoperative course was uneventful, without congestion in the gastric tube. In Case 1 where the short gastric vein had been used as the shunt vein, the long-term postoperative course was also uneventful, without hepatic encephalopathy or hemorrhage from deterioration of the varices of the gastric tube. However, in Case 2 where the left gastroepiploic vein had been used, hepatic encephalopathy developed due to excessive shunt flow. These results suggested that appropriate shunt flow could be expected by using short gastric vein.

Mycobacterium phocaicum bacteremia: an emerging infection in pediatric hematology-oncology patients.

PubMed

Shachor-Meyouhas, Yael; Geffen, Yuval; Arad-Cohen, Nira; Zaidman, Irina; Ben-Barak, Ayelet; Davidson, Sima; Kassis, Imad

2014-12-01

Nontuberculous mycobacteria may cause central venous catheter-associated bacteremia. Between March 2011 and October 2013, 6 cases of Mycobacterium phocaicum bacteremia were found in the pediatric hematology-oncology department. All patients recovered. No positive blood culture was documented after removal of the central venous catheter. All 4 patients with pulsed field gel electrophoresis had the same pattern, different from the water sample, suggesting a common water source.

Pulmonary venous flow index as a predictor of pulmonary vascular resistance variability in congenital heart disease with increased pulmonary flow: a comparative study before and after oxygen inhalation.

PubMed

Rivera, Ivan Romero; Mendonça, Maria Alayde; Andrade, José Lázaro; Moises, Valdir; Campos, Orlando; Silva, Célia Camelo; Carvalho, Antonio Carlos

2013-09-01

There is no definitive and reliable echocardiographic method for estimating the pulmonary vascular resistance (PVR) to differentiate persistent vascular disease from dynamic pulmonary hypertension. The aim of this study was to analyze the relationship between the pulmonary venous blood flow velocity-time integral (VTIpv) and PVR. Eighteen patients (10 females; 4 months to 22 years of age) with congenital heart disease and left to right shunt were studied. They underwent complete cardiac catheterization, including measurements of the PVR and Qp:Qs ratio, before and after 100% oxygen inhalation. Simultaneous left inferior pulmonary venous flow VTIpv was obtained by Doppler echocardiography. The PVR decreased significantly from 5.0 ± 2.6 W to 2.8 ± 2.2 W (P = 0.0001) with a significant increase in the Qp:Qs ratio, from 3.2 ± 1.4 to 4.9 ± 2.4 (P = 0.0008), and the VTIpv increased significantly from 22.6 ± 4.7 cm to 28.1 ± 6.2 cm (P = 0.0002) after 100% oxygen inhalation. VTIpv correlated well with the PVR and Qp:Qs ratio (r = -0.74 and 0.72, respectively). Diagnostic indexes indicated a sensitivity of 86%, specificity of 75%, accuracy of 83%, a positive predictive value of 92% and a negative predictive value of 60%. The VTIpv correlated well with the PVR. The measurement of this index before and after oxygen inhalation may become a useful noninvasive test for differentiating persistent vascular disease from dynamic and flow-related pulmonary hypertension. © 2013, Wiley Periodicals, Inc.

Thrombogenesis with continuous blood flow in the inferior vena cava. A novel mouse model.

PubMed

Diaz, José A; Hawley, Angela E; Alvarado, Christine M; Berguer, Alexandra M; Baker, Nichole K; Wrobleski, Shirley K; Wakefield, Thomas W; Lucchesi, Benedict R; Myers, Daniel D

2010-08-01

Several rodent models have been used to study deep venous thrombosis (DVT). However, a model that generates consistent venous thrombi in the presence of continuous blood flow, to evaluate therapeutic agents for DVT, is not available. Mice used in the present study were wild-type C57BL/6 (WT), plasminogen activator inhibitor-1 (PAI-1) knock out (KO) and Delta Cytoplasmic Tail (DCT). An electrolytic inferior vena cava (IVC) model (EIM) was used. A 25G stainless-steel needle, attached to a silver coated copper wire electrode (anode), was inserted into the exposed caudal IVC. Another electrode (cathode) was placed subcutaneously. A current of 250 muAmps over 15 minutes was applied. Ultrasound imaging was used to demonstrate the presence of IVC blood flow. Analyses included measurement of plasma soluble P-selectin (sP-Sel), thrombus weight (TW), vein wall morphometrics, P-selectin and Von Willebrand factor (vWF) staining, transmission electron microscopy (TEM), scanning electron microscopy (SEM); and the effect of enoxaparin on TW was evaluated. A current of 250 muAmps over 15 minutes consistently promoted thrombus formation in the IVC. Plasma sP-Sel was decreased in PAI-1 KO and increased in DCT vs. WT (WT/PAI-1: p=0.003, WT/DCT: p=0.0002). Endothelial activation was demonstrated by SEM, TEM, P-selectin and vWF immunohistochemistry and confirmed by inflammatory cell counts. Ultrasound imaging demonstrated thrombus formation in the presence of blood flow. Enoxaparin significantly reduced the thrombus size by 61% in this model. This EIM closely mimics clinical venous disease and can be used to study endothelial cell activation, leukocyte migration, thrombogenesis and therapeutic applications in the presence of blood flow.

Calibration of diffuse correlation spectroscopy blood flow index with venous-occlusion diffuse optical spectroscopy in skeletal muscle

PubMed Central

Li, Zhe; Baker, Wesley B.; Parthasarathy, Ashwin B.; Ko, Tiffany S.; Wang, Detian; Schenkel, Steven; Durduran, Turgut; Li, Gang; Yodh, Arjun G.

2015-01-01

Abstract. We investigate and assess the utility of a simple scheme for continuous absolute blood flow monitoring based on diffuse correlation spectroscopy (DCS). The scheme calibrates DCS using venous-occlusion diffuse optical spectroscopy (VO-DOS) measurements of arm muscle tissue at a single time-point. A calibration coefficient (γ) for the arm is determined, permitting conversion of DCS blood flow indices to absolute blood flow units, and a study of healthy adults (N=10) is carried out to ascertain the variability of γ. The average DCS calibration coefficient for the right (i.e., dominant) arm was γ=(1.24±0.15)×108 (mL·100  mL−1·min−1)/(cm2/s). However, variability can be significant and is apparent in our site-to-site and day-to-day repeated measurements. The peak hyperemic blood flow overshoot relative to baseline resting flow was also studied following arm-cuff ischemia; excellent agreement between VO-DOS and DCS was found (R2=0.95, slope=0.94±0.07, mean difference=−0.10±0.45). Finally, we show that incorporation of subject-specific absolute optical properties significantly improves blood flow calibration accuracy. PMID:26720870

Preoperative computer simulation for planning of vascular access surgery in hemodialysis patients.

PubMed

Zonnebeld, Niek; Huberts, Wouter; van Loon, Magda M; Delhaas, Tammo; Tordoir, Jan H M

2017-03-06

The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients. Unfortunately, 20-40% of all constructed AVFs fail to mature (FTM), and are therefore not usable for hemodialysis. AVF maturation importantly depends on postoperative blood volume flow. Predicting patient-specific immediate postoperative flow could therefore support surgical planning. A computational model predicting blood volume flow is available, but the effect of blood flow predictions on the clinical endpoint of maturation (at least 500 mL/min blood volume flow, diameter of the venous cannulation segment ≥4 mm) remains undetermined. A multicenter randomized clinical trial will be conducted in which 372 patients will be randomized (1:1 allocation ratio) between conventional healthcare and computational model-aided decision making. All patients are extensively examined using duplex ultrasonography (DUS) during preoperative assessment (12 venous and 11 arterial diameter measurements; 3 arterial volume flow measurements). The computational model will predict patient-specific immediate postoperative blood volume flows based on this DUS examination. Using these predictions, the preferred AVF configuration is recommended for the individual patient (radiocephalic, brachiocephalic, or brachiobasilic). The primary endpoint is FTM rate at six weeks in both groups, secondary endpoints include AVF functionality and patency rates at 6 and 12 months postoperatively. ClinicalTrials.gov (NCT02453412), and ToetsingOnline.nl (NL51610.068.14).

The Retrograde Transvenous Push-Through Method: A Novel Treatment of Peripheral Arteriovenous Malformations with Dominant Venous Outflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wohlgemuth, Walter A., E-mail: walter.wohlgemuth@ukr.de; Müller-Wille, René, E-mail: Rene.Mueller-Wille@ukr.de; Teusch, Veronika I., E-mail: Veronika.Teusch@gmx.de

2015-06-15

PurposeTo evaluate the efficacy and safety of a novel retrograde transvenous embolization technique of peripheral arteriovenous malformations (AVMs) using Onyx.Materials and MethodsWe conducted a retrospective analysis of all patients who underwent transvenous retrograde Onyx embolization of peripheral AVMs with dominant venous outflow over a 29-month period. The embolization is aimed at retrograde filling of the nidus after building a solid plug in the dominant venous outflow (push-through). Classification, clinical signs, technical aspects, clinical and technical success rates, and complications were recorded. Short-term outcome was assessed.Results11 Symptomatic patients (8 female; mean age 31.4 years) were treated at our Vascular Anomalies Center withmore » this method between January 2012 and May 2014. The AVMs were located on the upper extremity (n = 3), pelvis (n = 2), buttock (n = 2), and lower extremity (n = 4). Retrograde embolization was successfully carried out after preparatory transarterial-flow reduction in eight cases (73 %) and venous-flow reduction with Amplatzer Vascular Plugs in four cases (36 %). Complete devascularization (n = 10; 91 %) or 95 % devascularization (n = 1; 9 %) led to complete resolution (n = 8; 73 %) or improvement of clinical symptoms (n = 3; 27 %). One minor complication occurred (pain and swelling). During a mean follow-up time of 8 months, one clinically asymptomatic recurrence of AVM was detected.ConclusionInitial results suggest that retrograde transvenous Onyx embolization of peripheral AVMs with dominant venous outflow is a safe and effective novel technique with a low complication rate.« less

Blood flow vs. venous pressure effects on filtration coefficient in oleic acid-injured lung.

PubMed

Anglade, D; Corboz, M; Menaouar, A; Parker, J C; Sanou, S; Bayat, S; Benchetrit, G; Grimbert, F A

1998-03-01

On the basis of changes in capillary filtration coefficient (Kfc) in 24 rabbit lungs, we determined whether elevations in pulmonary venous pressure (Ppv) or blood flow (BF) produced differences in filtration surface area in oleic acid-injured (OA) or control (Con) lungs. Lungs were cyclically ventilated and perfused under zone 3 conditions by using blood and 5% albumin with no pharmacological modulation of vascular tone. Pulmonary arterial, venous, and capillary pressures were measured by using arterial, venous, and double occlusion. Before and during each Kfc-measurement maneuver, microvascular/total vascular compliance was measured by using venous occlusion. Kfc was measured before and 30 min after injury, by using a Ppv elevation of 7 cmH2O or a BF elevation from 1 to 2 l . min-1 . 100 g-1 to obtain a similar double occlusion pressure. Pulmonary arterial pressure increased more with BF than with Ppv in both Con and OA lungs [29 +/- 2 vs. 19 +/- 0.7 (means +/- SE) cmH2O; P < 0. 001]. In OA lungs compared with Con lungs, values of Kfc (200 +/- 40 vs. 83 +/- 14%, respectively; P < 0.01) and microvascular/total vascular compliance ratio (86 +/- 4 vs. 68 +/- 5%, respectively; P < 0.01) increased more with BF than with Ppv. In conclusion, for a given OA-induced increase in hydraulic conductivity, BF elevation increased filtration surface area more than did Ppv elevation. The steep pulmonary pressure profile induced by increased BF could result in the recruitment of injured capillaries and could also shift downstream the compression point of blind (zone 1) and open injured vessels (zone 2).

Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

PubMed

Karagiannidis, Christian; Kampe, Kristin Aufm; Sipmann, Fernando Suarez; Larsson, Anders; Hedenstierna, Goran; Windisch, Wolfram; Mueller, Thomas

2014-06-17

While non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH <7.20) still need intubation. Extracorporeal veno-venous CO2 removal (ECCO2R) could prove to be an alternative. The present animal study tested in a systematic fashion technical requirements for successful ECCO2R in terms of cannula size, blood and sweep gas flow. ECCO2R with a 0.98 m(2) surface oxygenator was performed in six acidotic (pH <7.20) pigs using either a 14.5 French (Fr) or a 19Fr catheter, with sweep gas flow rates of 8 and 16 L/minute, respectively. During each experiment the blood flow was incrementally increased to a maximum of 400 mL/minute (14.5Fr catheter) and 1000 mL/minute (19Fr catheter). Amelioration of severe respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH. Veno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

Integrative models of vascular remodeling during tumor growth

PubMed Central

Rieger, Heiko; Welter, Michael

2015-01-01

Malignant solid tumors recruit the blood vessel network of the host tissue for nutrient supply, continuous growth, and gain of metastatic potential. Angiogenesis (the formation of new blood vessels), vessel cooption (the integration of existing blood vessels into the tumor vasculature), and vessel regression remodel the healthy vascular network into a tumor-specific vasculature that is in many respects different from the hierarchically organized arterio-venous blood vessel network of the host tissues. Integrative models based on detailed experimental data and physical laws implement in silico the complex interplay of molecular pathways, cell proliferation, migration, and death, tissue microenvironment, mechanical and hydrodynamic forces, and the fine structure of the host tissue vasculature. With the help of computer simulations high-precision information about blood flow patterns, interstitial fluid flow, drug distribution, oxygen and nutrient distribution can be obtained and a plethora of therapeutic protocols can be tested before clinical trials. In this review, we give an overview over the current status of integrative models describing tumor growth, vascular remodeling, blood and interstitial fluid flow, drug delivery, and concomitant transformations of the microenvironment. © 2015 The Authors. WIREs Systems Biology and Medicine published by Wiley Periodicals, Inc. PMID:25808551

Measurement of gastrointestinal transmural electric potential difference in man.

PubMed

Geall, M G; Code, C F; McIlrath, D C; Summerskill, W H

1970-01-01

Measurement, in man, of the electric potential difference between venous blood and the mucosal surface of the gastrointestinal tract gave identical values to the potential difference between mucosa and serosa. Various parts of the peritoneum were equipotential with venous blood. By contrast, skin-enteric potential difference varied with time and among different subjects because of a potential difference between skin and blood that is unpredictably reduced by skin injury. The results with electrolyte bridges of KCl in agar or of flowing KCl were identical.

Measurement of gastrointestinal transmural electric potential difference in man

PubMed Central

Geall, Michael G.; Code, Charles F.; McIlrath, Donald C.; Summerskill, W. H. J.

1970-01-01

Measurement, in man, of the electric potential difference between venous blood and the mucosal surface of the gastrointestinal tract gave identical values to the potential difference between mucosa and serosa. Various parts of the peritoneum were equipotential with venous blood. By contrast, skin-enteric potential difference varied with time and among different subjects because of a potential difference between skin and blood that is unpredictably reduced by skin injury. The results with electrolyte bridges of KCl in agar or of flowing KCl were identical. PMID:5435266

Technical considerations in continuous jugular venous oxygen saturation measurement.

PubMed

Dearden, N M; Midgley, S

1993-01-01

Fibreoptic reflection oximetry allows continuous in-vivo estimation of jugular venous oxygen saturation. In combination with pulse oximetry the oxygen extraction ratio SaO2-SjO2/SaO2 can be derived enabling identification of states of global luxury perfusion, normal coupling of global cerebral blood flow with global cerebral metabolism, global cerebral hypoperfusion and global cerebral ischemia. Several technical difficulties may arise affecting the accuracy of SjO2 recordings which must be recognised by the clinician before medical intervention is contemplated.

Clinical features of venous insufficiency and the risk of venous thrombosis in older people.

PubMed

Engbers, Marissa J; Karasu, Alev; Blom, Jeanet W; Cushman, Mary; Rosendaal, Frits R; van Hylckama Vlieg, Astrid

2015-11-01

Venous thrombosis is common in older age, with an incidence of 0·5-1% per year in those aged >70 years. Stasis of blood flow is an important contributor to the development of thrombosis and may be due to venous insufficiency in the legs. The risk of thrombosis associated with clinical features of venous insufficiency, i.e., varicose veins, leg ulcers and leg oedema, obtained with a standardized interview was assessed in the Age and Thrombosis Acquired and Genetic risk factors in the Elderly (AT-AGE) study. The AT-AGE study is a case-control study in individuals aged 70 years and older (401 cases with a first-time venous thrombosis and 431 control subjects). We calculated odds ratios (ORs) and corresponding 95% confidence intervals (CI) adjusted for age, sex and study centre. Varicose veins and leg ulcer were associated with a 1·6-fold (95% CI 1·2-2·3) and 3·3-fold increased risk of thrombosis (95% CI 1·6-6·7), respectively, while the risk was increased 3·0-fold (95% CI 2·1-4·5) in the presence of leg oedema. The risk of thrombosis was highest when all three risk factors occurred simultaneously (OR: 10·5; 95% CI 1·3-86·1). In conclusion, clinical features of venous insufficiency, i.e., varicose veins, leg ulcers and leg oedema, are risk factors for venous thrombosis in older people. © 2015 John Wiley & Sons Ltd.

Role of nitric oxide and adenosine in control of coronary blood flow in exercising dogs.

PubMed

Tune, J D; Richmond, K N; Gorman, M W; Feigl, E O

2000-06-27

Inhibition of nitric oxide (NO) synthesis results in very little change in coronary blood flow, but this is thought to be because cardiac adenosine concentration increases to compensate for the loss of NO vasodilation. Accordingly, in the present study, adenosine measurements were made before and during NO synthesis inhibition during exercise. Experiments were performed in chronically instrumented dogs at rest and during graded treadmill exercise before and during inhibition of NO synthesis with N(omega)-nitro-L-arginine (L-NNA, 35 mg/kg IV). Before inhibition of NO synthesis, myocardial oxygen consumption increased approximately 3.7-fold, and coronary blood flow increased approximately 3.2-fold from rest to the highest level of exercise, and this was not changed by NO synthesis inhibition. Coronary venous oxygen tension was modestly reduced by L-NNA at all levels of myocardial oxygen consumption. However, the slope of the relationship between myocardial oxygen consumption and coronary venous oxygen tension was not altered by L-NNA. Inhibition of NO synthesis did not increase coronary venous plasma or estimated interstitial adenosine concentration. During exercise, estimated interstitial adenosine remained well below the threshold concentration necessary for coronary vasodilation before or after L-NNA. NO causes a modest coronary vasodilation at rest and during exercise but does not act as a local metabolic vasodilator. Adenosine does not mediate a compensatory local metabolic coronary vasodilation when NO synthesis is inhibited.

High Intracranial Pressure Induced Injury in the Healthy Rat Brain.

PubMed

Dai, Xingping; Bragina, Olga; Zhang, Tongsheng; Yang, Yirong; Rao, Gutti R; Bragin, Denis E; Statom, Gloria; Nemoto, Edwin M

2016-08-01

We recently showed that increased intracranial pressure to 50 mm Hg in the healthy rat brain results in microvascular shunt flow characterized by tissue hypoxia, edema, and increased blood-brain barrier permeability. We now determined whether increased intracranial pressure results in neuronal injury by Fluoro-Jade stain and whether changes in cerebral blood flow and cerebral metabolic rate for oxygen suggest nonnutritive microvascular shunt flow. Intracranial pressure was elevated by a reservoir of artificial cerebrospinal fluid connected to the cisterna magna. Arterial blood gases, cerebral arterial-venous oxygen content difference, and cerebral blood flow by MRI were measured. Fluoro-Jade stain neurons were counted in histologic sections of the right and left dorsal and lateral cortices and hippocampus. University laboratory. Male Sprague Dawley rats. Arterial pressure support if needed by IV dopamine infusion and base deficit corrected by sodium bicarbonate. Fluoro-Jade stain neurons increased 2.5- and 5.5-fold at intracranial pressures of 30 and 50 mm Hg and cerebral perfusion pressures of 57 ± 4 (mean ± SEM) and 47 ± 6 mm Hg, respectively (p < 0.001) (highest in the right and left cortices). Voxel frequency histograms of cerebral blood flow showed a pattern consistent with microvascular shunt flow by dispersion to higher cerebral blood flow at high intracranial pressure and decreased cerebral metabolic rate for oxygen. High intracranial pressure likely caused neuronal injury because of a transition from normal capillary flow to nonnutritive microvascular shunt flow resulting in tissue hypoxia and edema, and it is manifest by a reduction in the cerebral metabolic rate for oxygen.

Lifelike Vascular Reperfusion of a Thiel-Embalmed Pig Model and Evaluation as a Surgical Training Tool.

PubMed

Willaert, Wouter; Tozzi, Francesca; Van Hoof, Tom; Ceelen, Wim; Pattyn, Piet; D''Herde, Katharina

2016-01-01

Vascular reperfusion of Thiel cadavers can aid surgical and anatomical instruction. This study investigated whether ideal embalming circumstances provide lifelike vascular flow, enabling surgical practice and enhancing anatomical reality. Pressure-controlled pump-driven administration of blue embalming solution was assessed directly postmortem in a pig model (n = 4). Investigation of subsequent pump-driven vascular injection of red paraffinum perliquidum (PP) included assessment of flow parameters, intracorporeal distribution, anatomical alterations, and feasibility for surgical training. The microscopic distribution of PP was analyzed in pump-embalmed pig and gravity-embalmed human small intestines. Embalming lasted 50-105 min, and maximum arterial pressure was 65 mm Hg. During embalming, the following consecutive alterations were observed: arterial filling, organ coloration, venous perfusion, and further tissue coloration during the next weeks. Most organs were adequately preserved. PP generated low arterial pressures (<30 mm Hg) and drained through the venous cannula. Generally, realistic reperfusion and preservation of original anatomy were observed, but leakage in the pleural, abdominal, and retroperitoneal cavities occurred, and computed tomography showed edematous spleen and liver. Reduction of arterial flow rates after venous drainage is a prerequisite to prevent anatomical deformation, allowing simulation of various surgeries. In pump-embalmed pig small intestines, PP flowed from artery to vein through the capillaries without extravasation. In contrast, arterioles were blocked in gravity-embalmed human tissues. In a pig model, immediate postmortem pressure-controlled pump embalming generates ideal circumstances for (micro)vascular reperfusion with PP, permitting lifelike anatomy instruction and surgical training. © 2016 S. Karger AG, Basel.

Influence of protein ingestion on human splanchnic and whole-body oxygen consumption, blood flow, and blood temperature.

PubMed

Brundin, T; Wahren, J

1994-05-01

Splanchnic and whole-body oxygen uptake, blood flow, and blood temperature were studied in 10 healthy subjects before and during 2 hours after oral ingestion of 900 kJ of fish protein. Indirect calorimetry and catheter techniques were used, including blood thermometry in arterial, pulmonary arterial, and hepatic venous blood. After the meal, pulmonary oxygen uptake increased from a basal value of 272 +/- 11 to 332 +/- 23 mL/min. During the first postprandial hour, splanchnic oxygen uptake increased from 62 +/- 5 to 93 +/- 9 mL/min (+50%, P < .05), thereby accounting for 62% +/- 17% of the simultaneous increase in whole-body oxygen consumption. During the second postprandial hour, splanchnic oxygen uptake increased no further, whereas in the extrasplanchnic tissues the oxygen consumption increased, now accounting for the entire simultaneous increase in pulmonary oxygen uptake. Cardiac output increased from basal 6.4 +/- 0.4 to 7.5 +/- 0.5 L/min. Splanchnic blood flow changed little while the arteriohepatic venous oxygen difference increased from 46 +/- 3 to 54 +/- 4 mL/L. Arterial and hepatic venous blood temperatures increased by almost 0.3 degrees C, reflecting a considerable accumulation of heat, indicating a conversion into a positive thermal balance. It is concluded that after protein ingestion, (1) oxygen uptake increases mainly in the splanchnic organs during the first hour, and thereafter exclusively in the extrasplanchnic tissues; (2) the blood flow increases mainly in extrasplanchnic tissues; and (3) the blood temperature increases almost linearly, indicating an upward adjustment of the temperature setpoint in the central thermosensors.

Experiments of draining and filling processes in a collapsible tube at high external pressure

NASA Astrophysics Data System (ADS)

Flaud, P.; Guesdon, P.; Fullana, J.-M.

2012-02-01

The venous circulation in the lower limb is mainly controlled by the muscular action of the calf. To study the mechanisms governing the venous draining and filling process in such a situation, an experimental setup, composed by a collapsible tube under external pressure, has been built. A valve preventing back flows is inserted at the bottom of the tube and allows to model two different configurations: physiological when the fluid flow is uni-directional and pathological when the fluid flows in both directions. Pressure and flow rate measurements are carried out at the inlet and outlet of the tube and an original optical device with three cameras is proposed to measure the instantaneous cross-sectional area. The experimental results (draining and filling with physiological or pathological valves) are confronted to a simple one-dimensional numerical model which completes the physical interpretation. One major observation is that the muscular contraction induces a fast emptying phase followed by a slow one controlled by viscous effects, and that a defect of the valve decreases, as expected, the ejected volume.

Investigating the relationship between persistent reflux flow on the first postoperative day and recurrent varicocele in varicocelectomy patients.

PubMed

Cil, Ahmet Said; Bozkurt, Murat; Kara Bozkurt, Duygu; Gok, Mustafa

2015-01-01

The aim of this study was to investigate the presence of persistent reflux flow on the first postoperative day using color Doppler sonography (CDS) in patients who had undergone sub-inguinal varicocelectomy, and to research the relationship between persistent reflux flow and recurrent varicocele. A total of 54 patients were included in the study. Ages of the patients were between 21 and 38 years (mean 27.3 ± 7.6). All patients were evaluated four times with CDS: preoperatively, first postoperative day, 3 months postoperative, and finally 6 months after the operation. Preoperative venous diameters were measured between 3 and 5.5 mm; mean vein diameters were 3.8 ± 0.7 mm for the left side and 3.4 ± 0.4 mm for the right side. Mean duration of reflux was 3.5 ± 0.3 seconds on the left side and 2.9 ± 0.7 seconds on the right side. First postoperative day persistent Valsalva-induced reflux flow was seen in 10 patients (18%). Mean venous diameter was measured 1.8 ± 0.9 mm. Three months after the operation, Valsalva-induced reflux flow was seen in two patients (3%) in whom reflux was not seen on the first postoperative day. After 6 months, venous diameters larger than 2 mm at rest and the occurrence of reflux during the Valsalva maneuver were considered to be a recurrence. Six months after the operation, 12 patients had recurrent varicocele. Detecting persistent reflux with CDS on the first postoperative day was found to be 85% sensitive and 100% specific for showing recurrence. Valsalva-induced persistent reflux flow investigated with CDS on the first postoperative day can be used to show success of the surgery and is also an indicator of recurrence in varicocelectomy patients.

Management of venous leg ulcers in general practice - a practical guideline.

PubMed

Sinha, Sankar; Sreedharan, Sadhishaan

2014-09-01

Chronic venous leg ulcers are the most common wounds seen in general practice. Their management can be both challenging and time-consuming. To produce a short practical guideline incorporating the TIME concept and A2BC2D approach to help general practitioners and their practice nurses in delivering evidence-based initial care to patients with chronic venous leg ulcers. Most chronic venous leg ulcers can be managed effectively in the general practice setting by following the simple, evidence-based approach described in this article. Figure 1 provides a flow chart to aid in this process. Figure 2 illustrates the principles of management in general practice. Effective management of chronic ulcers involves the assessment of both the ulcer and the patient. The essential requirements of management are to debride the ulcer with appropriate precautions, choose dressings that maintain adequate moisture balance, apply graduated compression bandage after evaluation of the arterial circulation and address the patient's concerns, such as pain and offensive wound discharge.

Venous drainage of the face.

PubMed

Onishi, S; Imanishi, N; Yoshimura, Y; Inoue, Y; Sakamoto, Y; Chang, H; Okumoto, T

2017-04-01

The venous anatomy of the face was examined in 12 fresh cadavers. Venograms and arteriovenograms were obtained after the injection of contrast medium. In 8 of the 12 cadavers, a large loop was formed by the facial vein, the supratrochlear vein, and the superficial temporal vein, which became the main trunk vein of the face. In 4 of the 12 cadavers, the superior lateral limb of the loop vein was less well developed. The loop vein generally did not accompany the arteries of the face. Cutaneous branches of the loop vein formed a polygonal venous network in the skin, while communicating branches ran toward deep veins. These findings suggest that blood from the dermis of the face is collected by the polygonal venous network and enters the loop vein through the cutaneous branches, after which blood flows away from the face through the superficial temporal vein, the facial vein, and the communicating branches and enters the deep veins. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

[Digital blood flow measurement by venous occlusion plethysmography in Raynaud's phenomenon. Value of the rewarming test].

PubMed

Cristol, R; Debray, J

1986-01-01

The fingertip blood flow measured by mercury strain gauge plethysmography with venous occlusion, at 22 degrees C room temperature, had significantly lower mean values in 190 patients with Raynaud's phenomenon (55 men aged 49 yrs +/- 16, 135 women aged 48 yrs +/- 16) than in 40 age and sex matched controls: 18 ml/100 ml/minute +/- 14.6 versus 35 ml/100 ml/minute +/- 15 at level p less than 0.01. The mean fingertip blood flow was significantly lower (p less than 0.01) in 31 cases of scleroderma and 32 cases of pulpar necrosis (respectively 13 ml +/- 13 and 11 ml +/- 8) than in 55 cases of primary Raynaud's disease (no detectable etiology and normal capillaroscopy 5 years after onset) or in 34 cases of mild Raynaud's phenomenon (respectively 21.6 +/- 16 and 24.4 +/- 18). A warming test (both hands in water at 45 degrees C during 3 minutes) was performed in 50 cases with low basal fingertip blood flow. It induced a "normalized" flow in 22 cases (mostly primary or mild Raynaud), a partly improved flow in 20 cases (mostly secondary Raynaud) and no improvement in 8 cases (scleroderma). The warming test appears to be clinically useful to assess the vasospasm and the vasodilating capabilities.

Determining the appropriate number and duration of leech therapy in congested tissues using tissue spectrophotometry and laser Doppler flowmetry.

PubMed

Rothenberger, Jens; Petersen, Wiebke; Schaller, Hans-Eberhard; Held, Manuel

2016-11-01

A universal protocol determining the number of leeches and their application time does not exist. The aim of this study, therefore, is to quantify perfusion dynamics in venous congested tissues after leech application to get more detailed information about changes due to leech-induced skin microcirculation and to evaluate the usability of the Oxygen to See (O2C) device in terms of determining the appropriate number of leeches and the duration of therapy. Twelve patients with the need for leech therapy participated in the study. Perfusion dynamics of the congested tissue was assessed using the O2C device, which determines blood flow (BF), the relative amount of hemoglobin (rHB), and the oxygen saturation (SO2). Measurements were carried out before leech application and on various intervals like 10 minutes, one hour, and three hours after leech application. The leech application effectuated after 10 minutes a nonsignificant perfusion improvement, which further increased after one hour with a significant reduction of the relative amount of hemoglobin and a significant increase of blood flow and oxygen saturation (BF= +56.7%; rHB= -25.5%; SO2= +53.7%). After three hours, the values returned to the levels before leech administration. In two cases, in which further administration of leeches within the measurement period was necessary, no substantial perfusion changes were obtained. The results of this study forms a more precise pattern of microcirculatory changes of leech therapy in congested tissues. According to our measurements a venous drainage improvement can be expected in congested tissue one hour after leech administration. The O2C seems to be a useful method to determine the appropriate number and duration of leech therapy. © 2016 by the Wound Healing Society.

Optoacoustic monitoring of central and peripheral venous oxygenation during simulated hemorrhage

NASA Astrophysics Data System (ADS)

Petrov, Andrey; Kinsky, Michael; Prough, Donald S.; Petrov, Yuriy; Petrov, Irene Y.; Henkel, S. Nan; Seeton, Roger; Salter, Michael G.; Khan, Muzna N.; Esenaliev, Rinat O.

2014-03-01

Circulatory shock may be fatal unless promptly recognized and treated. The most commonly used indicators of shock (hypotension and tachycardia) lack sensitivity and specificity. In the initial stages of shock, the body compensates by reducing blood flow to the peripheral (skin, muscle, etc.) circulation in order to preserve vital organ (brain, heart, liver) perfusion. Characteristically, this can be observed by a greater reduction in peripheral venous oxygenation (for instance, the axillary vein) compared to central venous oxygenation (the internal jugular vein). While invasive measurements of oxygenation are accurate, they lack practicality and are not without complications. We have developed a novel optoacoustic system that noninvasively determines oxygenation in specific veins. In order to test this application, we used lower body negative pressure (LBNP) system, which simulates hemorrhage by exerting a variable amount of suction on the lower body, thereby reducing the volume of blood available for central circulation. Restoration of normal blood flow occurs promptly upon cessation of LBNP. Using two optoacoustic probes, guided by ultrasound imaging, we simultaneously monitored oxygenation in the axillary and internal jugular veins (IJV). LBNP began at -20 mmHg, thereafter was reduced in a step-wise fashion (up to 30 min). The optoacoustically measured axillary oxygenation decreased with LBNP, whereas IJV oxygenation remained relatively constant. These results indicate that our optoacoustic system may provide safe and rapid measurement of peripheral and central venous oxygenation and diagnosis of shock with high specificity and sensitivity.

Evaluation of anterior third of superior sagittal sinus in normal population: Identifying the subgroup with dominant drainage.

PubMed

Sahoo, Sushanta K; Ghuman, Mandeep S; Salunke, Pravin; Vyas, Sameer; Bhar, Rahat; Khandelwal, N K

2016-01-01

The ligation and transection of anterior third of superior sagittal sinus (AT-SSS) is an important step to approach anterior skull base lesions. Some clinical studies have shown frontal lobe venous infarct following such surgical procedures questioning the safety of its ligation. We have studied the variations in venous drainage patterns to AT-SSS in the normal population using postcontrast magnetic resonance venogram (MRV). A novel scoring system to recognize the subgroup with dominant venous drainage from frontal lobes has been described. In this study, 60 three-dimensional contrast-enhanced (CE) MRVs were obtained from those cases being evaluated for a headache not harboring any intracranial mass lesion. The AT-SSS with all its draining veins was studied in detail. Morphology of individual veins such as length, caliber, tributaries, and angulation with AT-SSS was studied, and a numerical value of 0 or 1 was assigned for each of the above parameters. Summing up these scores derived from the individual cortical veins quantified the drainage of AT-SSS. There are 3-4 veins on either side draining to AT-SSS. Barely, 3% of the veins had > 3 tributaries. Only 6.6% of veins had a caliber >3 mm, and 16.5% drained at acute angles to AT-SSS. About 26% of the veins did cross at least half of the lateral frontal lobe. We found in 26 individuals the AT-SSS score was 0-2, in 22 it was 3-5 and, in only in 12 (20%) the score was 6 or more (dominant drainage). There are anatomical variations in venous drainage of frontal lobes into AT-SSS. Those with dominant drainage are likely to develop venous congestion and complications if sacrificed. It is possible to identify these individuals on the basis of venous drainage pattern as shown in CE-MRV.

Presacral venous bleeding during mobilization in rectal cancer

PubMed Central

Casal Núñez, Jose Enrique; Vigorita, Vincenzo; Ruano Poblador, Alejandro; Gay Fernández, Ana María; Toscano Novella, Maria Ángeles; Cáceres Alvarado, Nieves; Pérez Dominguez, Lucinda

2017-01-01

AIM To analyze the anatomy of sacral venous plexus flow, the causes of injuries and the methods for controlling presacral hemorrhage during surgery for rectal cancer. METHODS A review of the databases MEDLINE® and Embase™ was conducted, and relevant scientific articles published between January 1960 and June 2016 were examined. The anatomy of the sacrum and its venous plexus, as well as the factors that influence bleeding, the causes of this complication, and its surgical management were defined. RESULTS This is a review of 58 published articles on presacral venous plexus injury during the mobilization of the rectum and on techniques used to treat presacral venous bleeding. Due to the lack of cases published in the literature, there is no consensus on which is the best technique to use if there is presacral bleeding during mobilization in surgery for rectal cancer. This review may provide a tool to help surgeons make decisions regarding how to resolve this serious complication. CONCLUSION A series of alternative treatments are described; however, a conventional systematic review in which optimal treatment is identified could not be performed because few cases were analyzed in most publications. PMID:28321171

Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins.

PubMed

Baltsavias, Gerasimos; Parthasarathi, Venkatraman; Aydin, Emre; Al Schameri, Rahman A; Roth, Peter; Valavanis, Anton

2015-04-01

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

The anatomy and physiology of the terminal thoracic duct and ostial valve in health and disease: potential implications for intervention.

PubMed

Ratnayake, Chathura Bathiya Bandara; Escott, Alistair Brian James; Phillips, Anthony Ronald John; Windsor, John Albert

2018-07-01

The thoracic duct (TD) transports lymph drained from the body to the venous system in the neck via the lymphovenous junction. There has been increased interest in the TD lymph (including gut lymph) because of its putative role in the promotion of systemic inflammation and organ dysfunction during acute and critical illness. Minimally invasive TD cannulation has recently been described as a potential method to access TD lymph for investigation. However, marked anatomical variability exists in the terminal segment and the physiology regarding the ostial valve and terminal TD is poorly understood. A systematic review was conducted using three databases from 1909 until May 2017. Human and animal studies were included and data from surgical, radiological and cadaveric studies were retrieved. Sixty-three articles from the last 108 years were included in the analysis. The terminal TD exists as a single duct in its terminal course in 72% of cases and 13% have multiple terminations: double (8.5%), triple (1.8%) and quadruple (2.2%). The ostial valve functions to regulate flow in relation to the respiratory cycle. The patency of this valve found at the lymphovenous junction opening, is determined by venous wall tension. During inspiration, central venous pressure (CVP) falls and the valve cusps collapse to allow antegrade flow of lymph into the vein. During early expiration when CVP and venous wall tension rises, the ostial valve leaflets cover the opening of the lymphovenous junction preventing antegrade lymph flow. During chronic disease states associated with an elevated mean CVP (e.g. in heart failure or cirrhosis), there is a limitation of flow across the lymphovenous junction. Although lymph production is increased in both heart failure and cirrhosis, TD lymph outflow across the lymphovenous junction is unable to compensate for this increase. In conclusion the terminal TD shows marked anatomical variability and TD lymph flow is controlled at the ostial valve, which responds to changes in CVP. This information is relevant to techniques for cannulating the TD, with the aid of minimally invasive methods and high resolution ultrasonography, to enable longitudinal physiology and lymph composition studies in awake patients with both acute and chronic disease. © 2018 Anatomical Society.

Venous haemodynamics of Jet Impulse Technology within a lower limb fibreglass cast: a randomized controlled trial

PubMed Central

Mackintosh, Stephen; Buchanan, Samantha; Schwarzenlander, Kerstin; De Ruyter, Bernadette

2017-01-01

Objectives We investigated popliteal venous haemodynamics of the VenaJet Jet Impulse Technology system within a below-knee fibreglass cast. Design Randomized controlled trial. Participants Twenty-four healthy participants aged 18–54 had both feet placed within the Jet Impulse Technology system and were randomised for one or other leg to be within a below-knee fibreglass cast. Setting Pacific Radiology, Lower Hutt, Wellington Main outcome measures The primary outcome variable was peak systolic velocity (cm/s) compared between legs with and without the cast at 60 min (after 10 min Jet Impulse Technology activation), using a mixed linear model and a non-inferiority bound of 4.8 cm/s. Secondary outcome variables were the difference in peak systolic velocity between the casted limb and the non-casted limb at baseline and 40 min after casting, and the difference in mean flow velocity (cm/s), vein diameter (mm), and total volume flow (L/min) between the casted limb and the non-casted limb at baseline, 40 and 60 min. Results The mean (standard deviation) peak systolic velocity was 4.6(1.5), 4.8(1.1), 28.8(16.1), and 4.3(1.2), 4.8(1.4) and 29.3(19.0) cm/s at baseline, 40 and 60 min in the casted and non-casted leg, respectively. The difference (95% confidence interval) between cast and no-cast at 60 min was −0.8 (−6.5 to 4.9) cm/s, P = 0.78. The peak systolic velocity, flow velocity and total volume flow at 40 min were not statistically significantly different from baseline for both casted and non-casted limb. Conclusion In healthy volunteers, the popliteal venous haemodynamics of the Jet Impulse Technology system was similar between the legs with and without a below-knee fibreglass cast. In-cast Jet Impulse Technology may provide a non-pharmacological option for venous thromboembolism prophylaxis for lower-limb cast-immobility. PMID:28203384

Intermittent KoldBlue cryotherapy of 3×10 min changes mid‐portion Achilles tendon microcirculation

PubMed Central

Knobloch, Karsten; Grasemann, Ruth; Spies, Marcus; Vogt, Peter M

2007-01-01

Background Neovascularisation and microcirculatory changes have been reported in Achilles tendinopathy. Cryotherapy and compression, as part of a rest, ice, compression and elevation regimen, are shown to decrease pain and improve function. However, the microcirculatory changes following a given dosage of cryotherapy on mid‐portion Achilles tendon remain unclear. Study design Prospective clinical cohort study, level of evidence 2. Methods 30 people (12 males, 33 (SD 12) years, body mass index 25.6 (5.3) kg/m2) were included in the cohort. 3×10 min KoldBlue ankle‐cooling bandages were applied and microcirculation of Achilles tendon mid‐portion was real‐time and continuously assessed using a laser‐Doppler‐spectrophotometry system (O2C, Germany). Results Superficial capillary blood flow was reduced from 42 to 6, 5 and 3 relative units (rU) in the first, second and third cryotherapy periods, respectively (−65%, p = 0.001), with no significant capillary hyperaemia. Deep capillary tendon blood flow was reduced from 180 to 82, 53 and 52 rU (−71%, p = 0.001) within 6–9 min of application without hyperaemia. Superficial tendon oxygen saturation dropped significantly from 43% to 26%, 18% and 11% (p = 0.001) after repetitive cryotherapy, with persisting increase of tendon oxygenation during rewarming (51%, 49% and 54%, p = 0.077) up to 27% of the baseline level. At 8 mm tendon depth, cryotherapy preserved local oxygenation. Relative postcapillary venous tendon filling pressures were favourably reduced from 41 (11) to 31, 28 and 26 rU (−36%, p = 0.001) superficially and from 56 (11) to 45, 46 and 48 rU (−18%, p = 0.001) in deep capillary blood flow during cryotherapy, facilitating capillary venous clearance. Conclusion Intermittent cryotherapy of 3×10 min significantly decreases local Achilles tendon mid‐portion capillary blood flow by 71%. Within 2 min of rewarming, tendon oxygen saturation is re‐established following cryotherapy. Postcapillary venous filling pressures are reduced during cryotherapy, favouring capillary venous outflow of the healthy Achilles tendon. PMID:17138636

Cardiovascular Deconditioning and Venous Air Embolism in Simulated Microgravity in the Rat

NASA Technical Reports Server (NTRS)

Robinson, R. R.; Doursout, M.-F.; Chelly, J. E.; Powell, M. R.; Little, T. M.; Butler,B. D.

1996-01-01

Astronauts conducting extravehicular activities undergo decompression to a lower ambient pressure, potentially resulting in gas bubble formation within the tissues and venous circulation. Additionally, exposure to microgravity produces fluid shifts within the body leading to cardiovascular deconditioning. A lower incidence of decompression illness in actual spaceflight compared with that in ground-based altitude chamber flights suggests that there is a possible interaction between microgravity exposure and decompression illness. The purpose of this study was to evaluate the cardiovascular and pulmonary effects of simulated hypobaric decompression stress using a tail suspension (head-down tilt) model of microgravity to produce the fluid shifts associated with weightlessness in conscious, chronically instrumented rats. Venous bubble formation resulting from altitude decompression illness was simulated by a 3-h intravenous air infusion. Cardiovascular deconditioning was simulated by 96 h of head-down tilt. Heart rate, mean arterial blood pressure, central venous pressure, left ventricular wall thickening and cardiac output were continuously recorded. Lung studies were performed to evaluate edema formation and compliance measurement. Blood and pleural fluid were examined for changes in white cell counts and protein concentration. Our data demonstrated that in tail-suspended rats subjected to venous air infusions, there was a reduction in pulmonary edema formation and less of a decrease in cardiac output than occurred following venous air infusion alone. Mean arterial blood pressure and myocardial wall thickening fractions were unchanged with either tail-suspension or venous air infusion. Heart rate decreased in both conditions while systemic vascular resistance increased. These differences may be due in part to a change or redistribution of pulmonary blood flow or to a diminished cellular response to the microvascular insult of the venous air embolization.

Simultaneous Iliac Vein Bovine Pericardial Patch Venoplasty and Creation of PTFE Lower Limb Arteriovenous Fistula Graft for Rescue Vascular Access.

PubMed

Meecham, Lewis; Fisher, Owain; Kirby, George; Evans, Richard; Buxton, Pauline; Legge, Jocelyn; Rajagopalan, Sriram; Asquith, John; Pherwani, Arun

2016-10-01

We present a case of external iliac vein patch venoplasty to accommodate rescue vascular access via a polytetrafluoroethylene loop arteriovenous fistula graft (AVG) for a patient with multiple central venous stenoses. A 35-year-old female with anti-glomerular basement membrane antibody disease required rescue vascular access for hemodialysis. Repeated occlusion and/or thrombosis of long-term central venous access cannulae, to facilitate dialysis, had caused stenosis of brachiocephalic veins: right external iliac vein and occlusion of the left common iliac vein. A previous right brachiobasilic fistula had occluded within 1 year. No other upper limb options for arteriovenous fistula (AVF) were available. A right external iliac vein bovine patch angioplasty concurrently with a polytetrafluoroethylene AV graft between common femoral artery and common femoral vein was performed to restore venous patency and allow rescue dialysis access. At 3-year follow-up, the fistula remains widely patent with 2 L/min flow rates and no recurrent stenosis to the treated iliac vein. She has not required any further surgical or interventional radiological procedures to maintain fistula or central venous patency. Central venous stenosis or occlusion is common for patients requiring dialysis, especially those with multiple previous long-term central venous cannulations. If restriction of outflow is present, AVF may fail. Venous patch angioplasty in these cases is a successful technique, allowing AVF formation and long-term patency. Central venous stenosis can be treated successfully with patch venoplasty to accommodate AVF/AVG formation for rescue vascular access; this is a potentially lifesaving intervention for patients requiring dialysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Use of ultraportable vacuum therapy systems in the treatment of venous leg ulcer.

PubMed

Cuomo, Roberto; Nisi, Giuseppe; Grimaldi, Luca; Brandi, Cesare; D'Aniello, Carlo

2017-10-23

The high incidence of venous leg ulcers and the difficult to give a complete healing involves in an increase of costs for National Health System. Main therapies to obtain a fast healing are compressive bandages, treatment of abnormal venous flow and in-situ-strategies of wound care. Negative pressure therapy does not conventionally used, because these systems not allow the use of compression bandages. Recently the development of ultraportable devices has improved the compliance and the results. Ten patients with venous chronic ulcer on the lower extremities were recruited for this study: all patients had venous leg ulcers from at least one year. We treated the patients with autologous partial thickness skin graft and subsequently we applied NANOVA device included in compressive bandage. We used NANOVA for fourteen days and after we made traditional medications. We submitted a questionnaire to evaluate the impact of dressing and NANOVA device in the quality of life of patients. The device contributed to the formation of granulation tissue and increased the success rate of autologous skin graft without limiting mobility of patient. In addition to this, we have been able to perform compression bandages thanks to small size of this device. Eight ulcers healed within 90 days of medication. We believe that ultraportable negative pressure systems are useful devices for treatment of venous leg ulcers because them allows to realize a compressive bandage without mobility limitations.

A global multiscale mathematical model for the human circulation with emphasis on the venous system.

PubMed

Müller, Lucas O; Toro, Eleuterio F

2014-07-01

We present a global, closed-loop, multiscale mathematical model for the human circulation including the arterial system, the venous system, the heart, the pulmonary circulation and the microcirculation. A distinctive feature of our model is the detailed description of the venous system, particularly for intracranial and extracranial veins. Medium to large vessels are described by one-dimensional hyperbolic systems while the rest of the components are described by zero-dimensional models represented by differential-algebraic equations. Robust, high-order accurate numerical methodology is implemented for solving the hyperbolic equations, which are adopted from a recent reformulation that includes variable material properties. Because of the large intersubject variability of the venous system, we perform a patient-specific characterization of major veins of the head and neck using MRI data. Computational results are carefully validated using published data for the arterial system and most regions of the venous system. For head and neck veins, validation is carried out through a detailed comparison of simulation results against patient-specific phase-contrast MRI flow quantification data. A merit of our model is its global, closed-loop character; the imposition of highly artificial boundary conditions is avoided. Applications in mind include a vast range of medical conditions. Of particular interest is the study of some neurodegenerative diseases, whose venous haemodynamic connection has recently been identified by medical researchers. Copyright © 2014 John Wiley & Sons, Ltd.

Changes in duration of action of rocuronium following decrease in hepatic blood flow during pneumoperitoneum for laparoscopic gynaecological surgery.

PubMed

Liu, Yang; Cao, Wen; Liu, Yu; Wang, Yun; Lang, Ren; Yue, Yun; Wu, An-Shi

2017-03-20

A moderate insufflation pressure and deep neuromuscular blockade (NMB) have been recommended in laparoscopic surgery in consideration of the possible reduction in splanchnic perfusion due to the CO 2 -pneumoperitoneum. Since the liver is the major organ for rocuronium metabolism, the question of whether NMB of rocuronium would change with the variation of liver perfusion during pneumoperitoneum during laparoscopic surgery merits investigation. In this prospective study, a total of sixty female patients scheduled for either selective laparoscopic gynaecological surgery (group laparoscopy) or laparotomy for gynaecological surgery (group control) were analyzed. Rocuronium was administered with closed-loop feedback infusion system, which was also applied to monitor NMB complied with good clinical research practice (GCRP). The onset time, clinical duration, and recovery index were measured. Hepatic blood flow was assessed by laparoscopic intraoperative ultrasonography before insufflation/after entering the abdominal cavity (T1), 5 min after insufflation in the Trendelenburg position/5 min after skin incision (T2), 15 min after insufflation in the Trendelenburg position/15 min after skin incision (T3), 30 min after insufflation in the Trendelenburg position/30 min after skin incision (T4), and 5 min after deflation/before closing the abdomen (T5) in group laparoscopy/group control respectively. The relationship between the clinical duration of rocuronium and portal venous blood flow was analyzed using linear or quadratic regression. The clinical duration and RI of rocuronium were both prolonged significantly in group laparoscopy (36.8 ± 8.3 min; 12.8 ± 5.5 min) compared to group control (29.0 ± 5.8 min; 9.8 ± 4.0 min) (P < 0.0001; P = 0.018). A significant decrease was found in portal venous blood flow during the entire pneumoperitoneum period in group laparoscopy compared with group control (P < 0.0001). There was a significant correlation between the clinical duration of rocuronium and portal venous blood flow (Y = 51.800-0.043X + (1.86E-005) X 2 ; r 2  = 0.491; P < 0.0001). Rocuronium-induced NMB during laparoscopic gynaecological surgery might be prolonged due to the decrease in portal venous blood flow induced by CO 2 -pneumoperitoneum. Less rocuronium could be required to achieve a desirable NMB in laparoscopic gynaecological surgery. ChiCTR. Registry number: ChiCTR-OPN-15007524 . Date of registration: December 4, 2015.

New Doppler echocardiographic applications for the study of diastolic function

NASA Technical Reports Server (NTRS)

Garcia, M. J.; Thomas, J. D.; Klein, A. L.

1998-01-01

Doppler echocardiography is one of the most useful clinical tools for the assessment of left ventricular (LV) diastolic function. Doppler indices of LV filling and pulmonary venous (PV) flow are used not only for diagnostic purposes but also for establishing prognosis and evaluating the effect of therapeutic interventions. The utility of these indices is limited, however, by the confounding effects of different physiologic variables such as LV relaxation, compliance and filling pressure. Since alterations in these variables result in changes in Doppler indices of opposite direction, it is often difficult to determine the status of a given variable when a specific Doppler filling pattern is observed. Recently, color M-mode and tissue Doppler have provided useful insights in the study of diastolic function. These new Doppler applications have been shown to provide an accurate estimate of LV relaxation and appear to be relatively insensitive to the effects of preload compensation. This review will focus on the complementary role of color M-mode and tissue Doppler echocardiography and traditional Doppler indices of LV filling and PV flow in the assessment of diastolic function.

Infrahepatic terminolateral cavocavostomy: a case report.

PubMed

Lima, C X; Garcia, S M; Lima, M B

2009-06-01

Infrahepatic vena cavocavostomy has been reported to be a rescue therapy when venous outflow from a liver allograft is obstructed due to stenosis of a piggyback anastomosis. The authors have described herein two consecutive adult liver transplantations using this technique as the primary venous anastomosis. Using a caval clamp positioned above the retrohepatic portion, partial hemodynamic obstruction of caval flow was well tolerated, avoiding use of a venovenous bypass. Although additional studies regarding this technique are needed, we believe that an infrahepatic vena cavocavostomy should be considered to be an alternative technique in carefully selected cases.

fMRI and EEG responses to periodic visual stimulation.

PubMed

Guy, C N; ffytche, D H; Brovelli, A; Chumillas, J

1999-08-01

EEG/VEP and fMRI responses to periodic visual stimulation are reported. The purpose of these experiments was to look for similar patterns in the time series produced by each method to help understand the relationship between the two. The stimulation protocol was the same for both sets of experiments and consisted of five complete cycles of checkerboard pattern reversal at 1.87 Hz for 30 s followed by 30 s of a stationary checkerboard. The fMRI data was analyzed using standard methods, while the EEG was analyzed with a new measurement of activation-the VEPEG. Both VEPEG and fMRI time series contain the fundamental frequency of the stimulus and quasi harmonic components-an unexplained double frequency commonly found in fMRI data. These results have prompted a reappraisal of the methods for analyzing fMRI data and have suggested a connection between our findings and much older published invasive electrophysiological measurements of blood flow and the partial pressures of oxygen and carbon dioxide. Overall our new analysis suggests that fMRI signals are strongly dependant on hydraulic blood flow effects. We distinguish three categories of fMRI signal corresponding to: focal activated regions of brain tissue; diffuse nonspecific regions of steal; and major cerebral vessels of arterial supply or venous drainage. Each category of signal has its own finger print in frequency, amplitude, and phase. Finally, we put forward the hypothesis that modulations in blood flow are not only the consequence but are also the cause of modulations in functional activity. Copyright 1999 Academic Press.

Hepatectomy for cholangiocarcinoma complicated with right umbilical portion: anomalous configuration of the intrahepatic biliary tree.

PubMed

Kaneoka, Y; Yamaguchi, A; Isogai, M; Harada, T

2000-01-01

The right umbilical portion (right-sided round ligament) has been discussed as an intrahepatic portal venous anomaly associated with "left-sided gallbladder" in several reports. We treated two patients with right umbilical portion (RUP) associated with cholangiocarcinoma. Left hepatectomies were performed, preserving the residual hepatic blood flow and biliary continuity. From our experience in these patients we propose the presence of anomalous configuration of the intrahepatic biliary tree in RUP, because both patients showed medial segmental bile ducts ramified from the right and left hepatic ducts. In general, although the medial segmental bile duct ramified from the left, we surmised that this abnormal bilateral drainage pattern may not be a rare phenomenon in RUP. Special attention may be required to focus on the anatomy of the portal tributaries and biliary ramifications in RUP.

Does cryotherapy improve skin circulation compared with compression and elevation in preventing venous leg ulcers?

PubMed

Kelechi, Teresa J; Mueller, Martina; Madisetti, Mohan; Prentice, Margie A; Dooley, Mary J

2017-08-01

This trial compared skin blood flow, temperature and incidence of venous leg ulcers in patients with chronic venous disease using compression wraps and elevation pillows. Patients with CEAP C4 skin damage and C5 history of ulcers were randomly assigned to a cryotherapy intervention (n = 138) or placebo cuff control (n = 138) applied to the lower legs over 9 months. The time the ulcers healed prior to enrollment in the study for the cryotherapy group ranged from 1 to 2218 days (n = 8, median = 32 days); for the control group, the range was 24 to 489 days (n = 6, median = 390 days). There were no statistically significant blood flow changes measured in perfusion units with a laser Doppler flowmetre within or between the groups; mean difference between the groups was 0·62, P = 0·619. No differences were noted in skin temperature measured with an infrared thermometer within and between the groups; mean difference between the groups was -0·17°C, P = 0·540. Cryotherapy did not improve skin blood flow or temperature and did not show efficacy in preventing ulcers. However, at least 30% of intervention and 50% of control participants were anticipated to develop an ulcer during the study; only ∼7% occurred. These findings suggest that strict adherence to standard of care decreases the incidence of leg ulcers and remains a best practice for leg ulcer prevention. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Endovascular treatment of iliofemoral deep vein thrombosis in pregnancy using US-guided percutaneous aspiration thrombectomy.

PubMed

Gedikoglu, Murat; Oguzkurt, Levent

2017-01-01

We aimed to describe ultrasonography (US)-guided percutaneous aspiration thrombectomy in pregnant women with iliofemoral deep vein thrombosis. This study included nine pregnant women with acute and subacute iliofemoral deep vein thrombosis, who were severe symptomatic cases with massive swelling and pain of the leg. Patients were excluded from the study if they had only femoropopliteal deep vein thrombosis or mild symptoms of deep vein thrombosis. US-guided percutaneous aspiration thrombectomy was applied to achieve thrombus removal and uninterrupted venous flow. The treatment was considered successful if there was adequate venous patency and symptomatic relief. Complete or significant thrombus removal and uninterrupted venous flow from the puncture site up to the iliac veins were achieved in all patients at first intervention. Complete relief of leg pain was achieved immediately in seven patients (77.8%). Two patients (22.2%) had a recurrence of thrombosis in the first week postintervention. One of them underwent a second intervention, where percutaneous aspiration thrombectomy was performed again with successful removal of thrombus and establishment of in line flow. Two patients were lost to follow-up after birth. None of the remaining seven patients had rethrombosis throughout the postpartum period. Symptomatic relief was detected clinically in these patients. Endovascular treatment with US-guided percutaneous aspiration thrombectomy can be considered as a safe and effective way to remove thrombus from the deep veins in pregnant women with acute and subacute iliofemoral deep vein thrombosis.

Endovascular treatment of iliofemoral deep vein thrombosis in pregnancy using US-guided percutaneous aspiration thrombectomy

PubMed Central

Gedikoglu, Murat; Oguzkurt, Levent

2017-01-01

PURPOSE We aimed to describe ultrasonography (US)-guided percutaneous aspiration thrombectomy in pregnant women with iliofemoral deep vein thrombosis. METHODS This study included nine pregnant women with acute and subacute iliofemoral deep vein thrombosis, who were severe symptomatic cases with massive swelling and pain of the leg. Patients were excluded from the study if they had only femoropopliteal deep vein thrombosis or mild symptoms of deep vein thrombosis. US-guided percutaneous aspiration thrombectomy was applied to achieve thrombus removal and uninterrupted venous flow. The treatment was considered successful if there was adequate venous patency and symptomatic relief. RESULTS Complete or significant thrombus removal and uninterrupted venous flow from the puncture site up to the iliac veins were achieved in all patients at first intervention. Complete relief of leg pain was achieved immediately in seven patients (77.8%). Two patients (22.2%) had a recurrence of thrombosis in the first week postintervention. One of them underwent a second intervention, where percutaneous aspiration thrombectomy was performed again with successful removal of thrombus and establishment of in line flow. Two patients were lost to follow-up after birth. None of the remaining seven patients had rethrombosis throughout the postpartum period. Symptomatic relief was detected clinically in these patients. CONCLUSION Endovascular treatment with US-guided percutaneous aspiration thrombectomy can be considered as a safe and effective way to remove thrombus from the deep veins in pregnant women with acute and subacute iliofemoral deep vein thrombosis. PMID:27801353

Brain oxygen saturation assessment in neonates using T2-prepared blood imaging of oxygen saturation and near-infrared spectroscopy.

PubMed

Alderliesten, Thomas; De Vis, Jill B; Lemmers, Petra Ma; Hendrikse, Jeroen; Groenendaal, Floris; van Bel, Frank; Benders, Manon Jnl; Petersen, Esben T

2017-03-01

Although near-infrared spectroscopy is increasingly being used to monitor cerebral oxygenation in neonates, it has a limited penetration depth. The T 2 -prepared Blood Imaging of Oxygen Saturation (T 2 -BIOS) magnetic resonance sequence provides an oxygen saturation estimate on a voxel-by-voxel basis, without needing a respiratory calibration experiment. In 15 neonates, oxygen saturation measured by T 2 -prepared blood imaging of oxygen saturation and near-infrared spectroscopy were compared. In addition, these measures were compared to cerebral blood flow and venous oxygen saturation in the sagittal sinus. A strong linear relation was found between the oxygen saturation measured by magnetic resonance imaging and the oxygen saturation measured by near-infrared spectroscopy ( R 2  = 0.64, p < 0.001). Strong linear correlations were found between near-infrared spectroscopy oxygen saturation, and magnetic resonance imaging measures of frontal cerebral blood flow, whole brain cerebral blood flow and venous oxygen saturation in the sagittal sinus ( R 2  = 0.71, 0.50, 0.65; p < 0.01). The oxygen saturation obtained by T 2 -prepared blood imaging of oxygen saturation correlated with venous oxygen saturation in the sagittal sinus ( R 2  = 0.49, p = 0.023), but no significant correlations could be demonstrated with frontal and whole brain cerebral blood flow. These results suggest that measuring oxygen saturation by T 2 -prepared blood imaging of oxygen saturation is feasible, even in neonates. Strong correlations between the various methods work as a cross validation for near-infrared spectroscopy and T 2 -prepared blood imaging of oxygen saturation, confirming the validity of using of these techniques for determining cerebral oxygenation.

The expression dynamics of mechanosensitive genes in extra-embryonic vasculature after heart starts to beat in chick embryo.

PubMed

Rajendran, Saranya; Sundaresan, Lakshmikirupa; Rajendran, Krithika; Selvaraj, Monica; Gupta, Ravi; Chatterjee, Suvro

2016-02-11

Fluid flow plays an important role in vascular development. However, the detailed mechanisms, particularly the link between flow and modulation of gene expression during vascular development, remain unexplored. In chick embryo, the key events of vascular development from initiation of heart beat to establishment of effective blood flow occur between the stages HH10 and HH13. Therefore, we propose a novel in vivo model to study the flow experienced by developing endothelium. Using this model, we aimed to capture the transcriptome dynamics of the pre- and post-flow conditions. RNA was isolated from extra embryonic area vasculosa (EE-AV) pooled from three chick embryos between HH10-HH13 and RNA sequencing was performed. The whole transcriptome sequencing of chick identified up-regulation of some of the previously well-known mechanosensitive genes including NFR2, HAND1, CTGF and KDR. GO analyses of the up-regulated genes revealed enrichment of several biological processes including heart development, extracellular matrix organization, cell-matrix adhesion, cell migration, blood vessel development, patterning of blood vessels, collagen fibril organization. Genes encoding for gap junctions proteins which are involved in vascular remodeling and arterial-venous differentiation, and genes involved in cell-cell adhesion, and ECM interactions were significantly up-regulated. Validation of selected genes through semi quantitative PCR was performed. The study indicates that shear stress plays a major role in development. Through appropriate validation, this platform can serve as an in vivo model to study conditions of disturbed flow in pathology as well as normal flow during development.

Differential Responses of Post-Exercise Recovery of Leg Blood Flow and Oxygen Uptake Kinetics in HFpEF versus HFrEF.

PubMed

Thompson, Richard B; Pagano, Joseph J; Mathewson, Kory W; Paterson, Ian; Dyck, Jason R; Kitzman, Dalane W; Haykowsky, Mark J

2016-01-01

The goals of the current study were to compare leg blood flow, oxygen extraction and oxygen uptake (VO2) after constant load sub-maximal unilateral knee extension (ULKE) exercise in patients with heart failure with reduced ejection fraction (HFrEF) compared to those with preserved ejection fraction (HFpEF). Previously, it has been shown that prolonged whole body VO2 recovery kinetics are directly related to disease severity and all-cause mortality in HFrEF patients. To date, no study has simultaneously measured muscle-specific blood flow and oxygen extraction post exercise recovery kinetics in HFrEF or HFpEF patients; therefore it is unknown if muscle VO2 recovery kinetics, and more specifically, the recovery kinetics of blood flow and oxygen extraction at the level of the muscle, differ between HF phenotypes. Ten older (68±10yrs) HFrEF (n = 5) and HFpEF (n = 5) patients performed sub-maximal (85% of maximal weight lifted during an incremental test) ULKE exercise for 4 minutes. Femoral venous blood flow and venous O2 saturation were measured continuously from the onset of end-exercise, using a novel MRI method, to determine off-kinetics (mean response times, MRT) for leg VO2 and its determinants. HFpEF and HFrEF patients had similar end-exercise leg blood flow (1.1±0.6 vs. 1.2±0.6 L/min, p>0.05), venous saturation (42±12 vs. 41±11%, p>0.05) and VO2 (0.13±0.08 vs. 0.11±0.05 L/min, p>0.05); however HFrEF had significantly delayed recovery MRT for flow (292±135sec. vs 105±63sec., p = 0.004) and VO2 (95±37sec. vs. 47±15sec., p = 0.005) compared to HFpEF. Impaired muscle VO2 recovery kinetics following ULKE exercise differentiated HFrEF from HFpEF patients and suggests distinct underlying pathology and potential therapeutic approaches in these populations.

In Vitro Evaluation of an Alternative Neonatal Extracorporeal Life Support Circuit on Hemodynamic Performance and Bubble Trap.

PubMed

Spencer, Shannon B; Wang, Shigang; Woitas, Karl; Glass, Kristen; Kunselman, Allen R; Ündar, Akif

2017-01-01

The objective of this study was to evaluate an alternative neonatal extracorporeal life support (ECLS) circuit with a RotaFlow centrifugal pump and Better-Bladder (BB) for hemodynamic performance and gaseous microemboli (GME) capture in a simulated neonatal ECLS system. The circuit consisted of a Maquet RotaFlow centrifugal pump, a Quadrox-iD Pediatric diffusion membrane oxygenator, 8 Fr arterial cannula, and 10 Fr venous cannula. A "Y" connector was inserted into the venous line to allow for comparison between BB and no BB. The circuit and pseudopatient were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 35%). All hemodynamic trials were conducted at flow rates ranging from 100 to 600 mL/min at 36°C. Real-time pressure and flow data were recorded using a data acquisition system. For GME testing, 0.5 cc of air was injected via syringe into the venous line. GME were detected and characterized with or without the BB using the Emboli Detection and Classification Quantifier (EDAC) System. Trials were conducted at flow rates ranging from 200 to 500 mL/min. The hemodynamic energy data showed that up to 75.2% of the total hemodynamic energy was lost from the circuit. The greatest pressure drops occurred across the arterial cannula and increased with increasing flow rate from 10.1 mm Hg at 100 mL/min to 114.3 mm Hg at 600 mL/min. The EDAC results showed that the BB trapped a significant amount of the GME in the circuit. When the bladder was removed, GME passed through the pump head and the oxygenator to the arterial line. This study showed that a RotaFlow centrifugal pump combined with a BB can help to significantly decrease the number of GME in a neonatal ECLS circuit. Even with this optimized alternative circuit, a large percentage of the total hemodynamic energy was lost. The arterial cannula was the main source of resistance in the circuit. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung.

PubMed

Park, M; Costa, E L V; Maciel, A T; Barbosa, E V S; Hirota, A S; Schettino, G de P; Azevedo, L C P

2014-11-01

Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes. Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows. Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow) and a negative association of pressure drop with temperature (-4.828 mmHg/(°Celsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined. During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0-5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature. © The Author(s) 2014.

Maternal diabetes alters the development of ductus venosus shunting in the fetus.

PubMed

Lund, Agnethe; Ebbing, Cathrine; Rasmussen, Svein; Kiserud, Torvid W; Kessler, Jörg

2018-05-11

Despite adequate glycemic control, the risks of fetal macrosomia and perinatal complications are increased in diabetic pregnancies. Adjustments of the umbilical venous (UV) distribution, including increased ductus venosus (DV) shunting, can be important fetal compensatory mechanisms, but the impact of pregestational diabetes on UV and DV flow is not known. In this prospective study, 49 women with pregestational diabetes mellitus underwent monthly ultrasound examinations from gestational week 20 to 36. The blood velocity and the mean diameters of the UV and DV were used for calculating blood flow volumes. The development of the UV flow, DV flow and DV shunt fraction (% of UV blood shunted through the DV) was compared with a reference population, and the effect of HbA 1c on the DV flow was assessed. The UV flow was larger in pregnancies with pregestational diabetes mellitus than in low-risk pregnancies (p<0.001), but smaller when normalized for fetal weight (p=0.036). The distributional pattern of the DV flow developed differently in diabetic pregnancies, particularly during the third trimester, being smaller (p=0.007), also when normalized for fetal weight (p<0.001). Correspondingly the DV shunt fraction was reduced (p<0.0001), most prominently at 36 weeks. There were negative relations between the maternal HbA 1c and the DV flow velocity, flow volume and shunt fraction. In pregnancies with pregestational diabetes mellitus, prioritized UV distribution to the fetal liver, and lower DV shunt capacity, both reduce the compensatory capability of the fetus and may represent an augmented risk during hypoxic challenges during late pregnancy and birth. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Classification of the venous architecture of the pineal gland by 7T MRI.

PubMed

Cho, Zang-Hee; Choi, Sang-Han; Chi, Je-Gun; Kim, Young-Bo

2011-10-01

Magnetic resonance imaging (MRI) at 7.0 Tesla (7T) can show many details of anatomical structures with unprecedented resolution and contrast. In this report, we describe for the first time the unexpected wide variation in pineal gland structure, as visualized by MR images obtained with 7T in a group of healthy young volunteers. A total of 34 volunteers (22 men and 12 women) were enrolled in the study. Their 7T MR images revealed such wide variations in pineal gland shape that it led us to attempt to classify the patterns seen in these pineal glands. Indeed, they were successfully correlated with a previous human cadaver study of venous structures by Tamaki et al., who classified the venous structures of the pineal gland into three categories. This is the first human in vivo pineal vein imaging study using 7T MRI. Pineal venous imaging may permit the early diagnosis of a pineal tumor. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Effects of forearm bier block with bretylium on the hemodynamic and metabolic responses to handgrip

NASA Technical Reports Server (NTRS)

Lee, F.; Shoemaker, J. K.; McQuillan, P. M.; Kunselman, A. R.; Smith, M. B.; Yang, Q. X.; Smith, H.; Gray, K.; Sinoway, L. I.

2000-01-01

We tested the hypothesis that a reduction in sympathetic tone to exercising forearm muscle would increase blood flow, reduce muscle acidosis, and attenuate reflex responses. Subjects performed a progressive, four-stage rhythmic handgrip protocol before and after forearm bier block with bretylium as forearm blood flow (Doppler) and metabolic (venous effluent metabolite concentration and (31)P-NMR indexes) and autonomic reflex responses (heart rate, blood pressure, and sympathetic nerve traffic) were measured. Bretylium inhibits the release of norepinephrine at the neurovascular junction. Bier block increased blood flow as well as oxygen consumption in the exercising forearm (P < 0.03 and P < 0.02, respectively). However, despite this increase in flow, venous K(+) release and H(+) release were both increased during exercise (P < 0.002 for both indexes). Additionally, minimal muscle pH measured during the first minute of recovery with NMR was lower after bier block (6.41 +/- 0.08 vs. 6.20 +/- 0.06; P < 0.036, simple effects). Meanwhile, reflex effects were unaffected by the bretylium bier block. The results support the conclusion that sympathetic stimulation to muscle during exercise not only limits muscle blood flow but also appears to limit anaerobiosis and H(+) release, presumably through a preferential recruitment of oxidative fibers.

Numerical analysis of Venous External Scaffolding Technology for Saphenous Vein Grafts.

PubMed

Meirson, T; Orion, E; Avrahami, I

2015-07-16

This paper presents a method for analyzing and comparing numerically Saphenous Vein Grafts (SVGs) following Coronary Artery Bypass Graft surgery (CABG). The method analyses the flow dynamics inside vein grafts with and without supporting using Venous External Scaffolding Technology (VEST). The numerical method uses patients׳ specific computational fluid dynamics (CFD) methods to characterize the relevant hemodynamic parameters of patients׳ SVGs. The method was used to compare the hemodynamics of six patient׳s specific model and flow conditions of stented and non-stented SVGs, 12 months post-transplantation. The flow parameters used to characterize the grafts׳ hemodynamics include Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI) and Relative Residence Time (RRT). The effect of stenting was clearly demonstrated by the chosen parameters. SVGs under constriction of VEST were associated with similar spatial average of TAWSS (10.73 vs 10.29 dyn/cm(2)), yet had fewer lesions with low TAWSS, lower OSI (0.041 vs 0.08) and RRT (0.12 vs 0.24), and more uniform flow with less flow discrepancies. In conclusion, the suggested method and parameters well demonstrated the advantage of VEST support. Stenting vein grafts with VEST improved hemodynamic factors which are correlated to graft failure following CABG procedure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Real-time magnetic resonance imaging of deep venous flow during muscular exercise-preliminary experience.

PubMed

Joseph, Arun Antony; Merboldt, Klaus-Dietmar; Voit, Dirk; Dahm, Johannes; Frahm, Jens

2016-12-01

The accurate assessment of peripheral venous flow is important for the early diagnosis and treatment of disorders such as deep-vein thrombosis (DVT) which is a major cause of post-thrombotic syndrome or even death due to pulmonary embolism. The aim of this work is to quantitatively determine blood flow in deep veins during rest and muscular exercise using a novel real-time magnetic resonance imaging (MRI) method for velocity-encoded phase-contrast (PC) MRI at high spatiotemporal resolution. Real-time PC MRI of eight healthy volunteers and one patient was performed at 3 Tesla (Prisma fit, Siemens, Erlangen, Germany) using a flexible 16-channel receive coil (Variety, NORAS, Hoechberg, Germany). Acquisitions were based on a highly undersampled radial FLASH sequence with image reconstruction by regularized nonlinear inversion at 0.5×0.5×6 mm 3 spatial resolution and 100 ms temporal resolution. Flow was assessed in two cross-sections of the lower leg at the level of the calf muscle and knee using a protocol of 10 s rest, 20 s flexion and extension of the foot, and 10 s rest. Quantitative analyses included through-plane flow in the right posterior tibial, right peroneal and popliteal vein (PC maps) as well as signal intensity changes due to flow and muscle movements (corresponding magnitude images). Real-time PC MRI successfully monitored the dynamics of venous flow at high spatiotemporal resolution and clearly demonstrated increased flow in deep veins in response to flexion and extension of the foot. In normal subjects, the maximum velocity (averaged across vessel lumen) during exercise was 9.4±5.7 cm·s -1 for the right peroneal vein, 8.5±4.6 cm·s -1 for the right posterior tibial vein and 17.8±5.8 cm·s -1 for the popliteal vein. The integrated flow volume per exercise (20 s) was 1.9, 1.6 and 50 mL (mean across subjects) for right peroneal, right posterior tibial and popliteal vein, respectively. A patient with DVT presented with peak flow velocities of only about 2 cm·s -1 during exercise and less than 1 cm·s -1 during rest. Real-time PC MRI emerges as a new tool for quantifying the dynamics of muscle-induced flow in deep veins. The method provides both signal intensity changes and velocity information for the assessment of blood flow and muscle movements. It now warrants extended clinical trials to patients with suspected thrombosis.

Compact dual-mode diffuse optical system for blood perfusion monitoring in a porcine model of microvascular tissue flaps

NASA Astrophysics Data System (ADS)

Lee, Seung Yup; Pakela, Julia M.; Helton, Michael C.; Vishwanath, Karthik; Chung, Yooree G.; Kolodziejski, Noah J.; Stapels, Christopher J.; McAdams, Daniel R.; Fernandez, Daniel E.; Christian, James F.; O'Reilly, Jameson; Farkas, Dana; Ward, Brent B.; Feinberg, Stephen E.; Mycek, Mary-Ann

2017-12-01

In reconstructive surgery, the ability to detect blood flow interruptions to grafted tissue represents a critical step in preventing postsurgical complications. We have developed and pilot tested a compact, fiber-based device that combines two complimentary modalities-diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy-to quantitatively monitor blood perfusion. We present a proof-of-concept study on an in vivo porcine model (n=8). With a controllable arterial blood flow supply, occlusion studies (n=4) were performed on surgically isolated free flaps while the device simultaneously monitored blood flow through the supplying artery as well as flap perfusion from three orientations: the distal side of the flap and two transdermal channels. Further studies featuring long-term monitoring, arterial failure simulations, and venous failure simulations were performed on flaps that had undergone an anastomosis procedure (n=4). Additionally, benchtop verification of the DCS system was performed on liquid flow phantoms. Data revealed relationships between diffuse optical measures and state of occlusion as well as the ability to detect arterial and venous compromise. The compact construction of the device, along with its noninvasive and quantitative nature, would make this technology suitable for clinical translation.

Evaluation of peripheral vasodilative indices in skin tissue of type 1 diabetic rats by use of RGB images

NASA Astrophysics Data System (ADS)

Tanaka, Noriyuki; Nishidate, Izumi; Nakano, Kazuya; Aizu, Yoshihisa; Niizeki, Kyuichi

2016-04-01

We investigated a method to evaluate the arterial inflow and the venous capacitance in the skin tissue of streptozotocin-induced type 1 diabetic rats from RGB digital color images. The arterial inflow and the venous capacitance in the dorsal reversed McFarlane skin flap are calculated based on the responses of change in the total blood concentration to occlusion of blood flow to and from the flap tissues at a pressure of 50 mmHg. The arterial inflow and the venous capacitance in the skin flap tissue were significantly reduced in type 1 diabetic rat group compared with the non-diabetic rat group. The results of the present study indicate the possibility of using the proposed method for evaluating the peripheral vascular dysfunctions in diabetes mellitus.

Venous Small Bowel Infarction: Intraoperative Laser Doppler Flowmetry Discriminates Critical Blood Supply and Spares Bowel Length

PubMed Central

Käser, S. A.; Glauser, P. M.; Maurer, C. A.

2012-01-01

Introduction. In mesenteric infarction due to arterial occlusion, laser Doppler flowmetry and spectrometry are known reliable noninvasive methods for measuring microvascular blood flow and oxygen utilisation. Case Presentation. As an innovation we used these methods in a patient with acute extensive mesenteric infarction due to venous occlusion, occurring after radical right hemicolectomy. Aiming to avoid short bowel syndrome, we spared additional 110 cm of small bowel, instead of leaving only 80 centimetres of clinically viable small bowel in situ. The pathological examination showed only 5 mm of vital mucosa to be left distal to the dissection margin. No further interventions were necessary. Conclusion. Laser doppler flowmetry and spectrometry are potentially powerful methods to assist the surgeon's decision-making in critical venous mesenteric perfusion, thus having an important impact on clinical outcome. PMID:23093968

Angio-Architectural Features of High-Grade Intracranial Dural Arteriovenous Fistulas: Correlation With Aggressive Clinical Presentation and Hemorrhagic Risk.

PubMed

Della Pepa, Giuseppe Maria; Parente, Paolo; D'Argento, Francesco; Pedicelli, Alessandro; Sturiale, Carmelo Lucio; Sabatino, Giovanni; Albanese, Alessio; Puca, Alfredo; Fernandez, Eduardo; Olivi, Alessando; Marchese, Enrico

2017-08-01

High-grade dural arteriovenous fistulas (dAVFs) can present shunts with very different angio-architectural characteristics. Specific hemodynamic factors may affect clinical history and determine very different clinical courses. To evaluate the relationship between some venous angio-architectural features in high-grade dAVFs and clinical presentation. Specific indicators of moderate or severe venous hypertension were analyzed, such as altered configurations of the dural sinuses (by a single or a dual thrombosis), or overload of cortical vessels (restrictions of outflow, pseudophlebitic cortical vessels, and venous aneurysms). The institutional series was retrospectively reviewed (49 cases), and the pattern of venous drainage was analyzed in relationship with clinical presentation (benign/aggressive/hemorrhage). Thirty-five of 49 cases displayed cortical reflux (high-grade dAVFs). This subgroup displayed a benign presentation in 31.42% of cases, an aggressive in 31.42%, and hemorrhage in 37.14%. Our data confirm that within high-grade dAVFs, 2 distinct subpopulations exist according to severity of clinical presentation. Some indicators we examined showed correlation with aggressive nonhemorrhagic manifestations (outflow restriction and pseudophlebitic cortical vessels), while other showed a correlation with hemorrhage (dual thrombosis and venous aneurysms). Current classifications appear insufficient to identify a wide range of conditions that ultimately determine the organization of the cortical venous drainage. Intermediate degrees of venous congestion correlate better with the clinical risk than the simple definition of cortical reflux. The angiographic aspects of venous drainage presented in this study may prove useful to assess dAVF hemodynamic characteristics and identify conditions at higher clinical risk. Copyright © 2017 by the Congress of Neurological Surgeons

Effects of postural changes and removal of vestibular inputs on blood flow to and from the hindlimb of conscious felines

PubMed Central

Yavorcik, K. J.; Reighard, D. A.; Misra, S. P.; Cotter, L. A.; Cass, S. P.; Wilson, T. D.

2009-01-01

Considerable data show that the vestibular system contributes to blood pressure regulation. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious cats during 20–60° head-up tilts from the prone position before and after removal of vestibular inputs. In vestibular-intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts and, at 5 s after the initiation of 60° rotations, was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 s, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals, venous return was facilitated, such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure. PMID:19793952

Perimesencephalic nonaneurysmal subarachnoid hemorrhage caused by transverse sinus thrombosis: A case report and review of literature.

PubMed

Fu, Fang-Wang; Rao, Jie; Zheng, Yuan-Yuan; Song, Liang; Chen, Wei; Zhou, Qi-Hui; Yang, Jian-Guang; Ke, Jiang-Qiong; Zheng, Guo-Qing

2017-08-01

Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is characterized by a pattern of extravasated blood restricted to the perimesencephalic cisterns, normal angiographic findings, and an excellent prognosis with an uneventful course and low risks of complication. The precise etiology of bleeding in patients with PNSAH has not yet been established. The most common hypothesis is that PNSAH is venous in origin. Intracranial venous hypertension has been considered as the pivotal factor in the pathogenesis of PNSAH. The underlying venous pathology such as straight sinus stenosis, jugular vein occlusion may contribute to PNSAH. We describe a patient in whom transverse sinus thrombosis preceded intracranial venous hypertension and PNSAH. These findings supported that the source of the subarachnoid hemorrhage is venous in origin. A 45-year-old right-handed man was admitted to the hospital with a sudden onset of severe headache associated with nausea, vomiting, and mild photophobia for 6 hours. The patient was fully conscious and totally alert. An emergency brain computed tomography (CT) revealed an acute subarachnoid hemorrhage restricted to the perimesencephalic cisterns. CT angiography revealed no evidence of an intracranial aneurysm or underlying vascular malformation. Digital subtraction angiography of arterial and capillary phases confirmed the CT angiographic findings. Assessment of the venous phase demonstrated right transverse sinus thrombosis. Magnetic resonance imaging confirmed the diagnosis of cerebral venous sinus thrombosis (CVST). Lumbar puncture revealed an opening pressure of 360 mmH2O, suggestive of intracranial venous hypertension. Grave disease was diagnosed by endocrinological investigation. Low-molecular-weight heparin, followed by oral warfarin, was initiated immediately as the treatment for cerebral venous sinus thrombosis and PNSAH. The patient discharged without any neurologic defect after 3 weeks of hospital stay. MR venography revealed recanalization of right transverse sinus at the 6-month follow-up. No clinical or neuroimaging evidence of relapse was detected at 12 months follow-up. Hyperthyroidism may contribute to the development of CVST. The presence of acute transverse sinus thrombosis, as a cause of PNSAH, provides further support for the hypothesis that the source of PNSAH is venous in origin and intracranial venous hypertension plays a critical role in the pathogenesis of PNSAH.

Portal hypertension in patients with cirrhosis: indirect assessment of hepatic venous pressure gradient by measuring azygos flow with 2D-cine phase-contrast magnetic resonance imaging.

PubMed

Gouya, Hervé; Grabar, Sophie; Vignaux, Olivier; Saade, Anastasia; Pol, Stanislas; Legmann, Paul; Sogni, Philippe

2016-07-01

To measure azygos, portal and aortic flow by two-dimensional cine phase-contrast magnetic resonance imaging (2D-cine PC MRI), and to compare the MRI values to hepatic venous pressure gradient (HVPG) measurements, in patients with cirrhosis. Sixty-nine patients with cirrhosis were prospectively included. All patients underwent HVPG measurements, upper gastrointestinal endoscopy and 2D-cine PC MRI measurements of azygos, portal and aortic blood flow. Univariate and multivariate regression analyses were used to evaluate the correlation between the blood flow and HVPG. The performance of 2D-cine PC MRI to diagnose severe portal hypertension (HVPG ≥ 16 mmHg) was determined by receiver operating characteristic curve (ROC) analysis, and area under the curves (AUC) were compared. Azygos and aortic flow values were associated with HVPG in univariate linear regression model. Azygos flow (p < 10(-3)), aortic flow (p = 0.001), age (p = 0.001) and presence of varices (p < 10(-3)) were independently associated with HVPG. Azygos flow (AUC = 0.96 (95 % CI [0.91-1.00]) had significantly higher AUC than aortic (AUC = 0.64 (95 % CI [0.51-0.77]) or portal blood flow (AUC = 0.40 (95 % CI [0.25-0.54]). 2D-cine PC MRI is a promising technique to evaluate significant portal hypertension in patients with cirrhosis. • Noninvasive HVPG assessment can be performed with MRI azygos flow. • Azygos MRI flow is an easy-to-measure marker to detect significant portal hypertension. • MRI flow is more specific that varice grade to detect portal hypertension.

Evaluation of Marrow Perfusion in the Femoral Head by Dynamic Magnetic Resonance Imaging

PubMed Central

Tsukamoto, Hiroshi; Kang, Young S.; Jones, Lynne C.; Cova, Maria; Herold, Christian J.; McVeigh, Elliot; Hungerford, David S.; Zerhouni, Elias A.

2007-01-01

Rationale and Objectives There is a continuing need for a greater sensitivity of magnetic resonance imaging (MRI) in the diagnosis of avascular necrosis (AVN). Previously, it was demonstrated that a dynamic MRI method, with gadolinium-DTPA (Gd-DTPA) enhancement, can detect acute changes not seen on spin-echo images after arterial occlusion in a dog model. Because venous congestion appears to be a more directly relevant hemodynamic abnormality in a majority of clinical AVN cases, the authors extended the dynamic MRI technique to study changes in venous occlusion. Methods Dynamic MRI of the proximal femur was performed in five adult dogs before and after unilateral ligation of common iliac and lateral circumflex veins. Sixteen sequential gradient-recalled pulse sequence (GRASS) images (time resolution = 45 mseconds, echo time = 9 mseconds, flip angle = 65°) were obtained immediately after a bolus intravenous injection of 0.2 mmol/kg of Gd-DTPA. Simultaneous measurements of regional blood flow were made using the radioactive microsphere method. Results After venous ligation, there was a 25% to 45% decrease in the degree of enhancement compared with preligation values on the ligated side. The decrease in cumulative enhancement (integrated over the entire time course) was statistically significant. The occlusion technique was verified by confirming a statistically significant decrease in blood flow determined by the microsphere method. Conclusions Dynamic Gd-DTPA-enhanced fast MRI technique can detect acute changes in bone marrow perfusion due to venous occlusion. This technique may have applications in the early detection of nontraumatic AVN. PMID:1601616

Monitoring Changes in Hepatic Venous Velocities Flow after a Fluid Challenge Can Identify Shock Patients Who Lack Fluid Responsiveness

PubMed Central

Du, Wei; Wang, Xiao-Ting; Long, Yun; Liu, Da-Wei

2017-01-01

Background: Evaluating the hemodynamic status and predicting fluid responsiveness are important in critical ultrasound assessment of shock patients. Transthoracic echocardiography with noninvasive diagnostic parameters allows the assessment of volume responsiveness. This study aimed to assess the hemodynamic changes in the liver and systemic hemodynamic changes during fluid challenge and during passive leg raising (PLR) by measuring hepatic venous flow (HVF) velocity. Methods: This is an open-label study in a tertiary teaching hospital. Shock patients with hypoperfusion who required fluid challenge were selected for the study. Patients <18 years old and those with contraindications to PLR were excluded from the study. Baseline values were measured, PLR tests were performed, and 500 ml of saline was infused over 30 min. Parameters associated with cardiac output (CO) in the left ventricular outflow tract were measured using the Doppler method. In addition, HVF velocity and right ventricular function parameters were determined. Results: Middle hepatic venous (MHV) S-wave velocity was positively correlated in all patients with CO at baseline (r = 0.706, P < 0.01) and after volume expansion (r = 0.524, P = 0.003). CO was also significantly correlated with MHV S-wave velocity in responders (r = 0.608, P < 0.01). During PLR, however, hepatic venous S-wave velocity did not correlate with CO. For the parameter ΔMHV D (increase in change in MHV D-wave velocity after volume expansion), defined as (MHV DafterVE − MHV DBaseline)/MHV DBaseline × 100%, >21% indicated no fluid responsiveness, with a sensitivity of 100%, a specificity of 71.2%, and an area under the receiver operating characteristic curve of 0.918. Conclusions: During fluid expansion, hepatic venous S-wave velocity can be used to monitor CO, whether or not it is increasing. ΔMHV D ≥21% indicated a lack of fluid responsiveness, thus helping to decide when to stop infusions. PMID:28485321

Time of flight MR angiography assessment casts doubt on the association between transient global amnesia and intracranial jugular venous reflux.

PubMed

Kang, Yeonah; Kim, Eunhee; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheolkyu; Bae, Yun Jung; Lee, Kyung Mi; Lee, Dong Hoon

2015-03-01

Evidence of intracranial venous reflux flow due to jugular venous reflux (JVR) on time of flight (TOF) MR angiography (MRA) is thought to be highly associated with transient global amnesia (TGA)-evidence that supports the venous congestion theory of TGA pathophysiology. However, recent studies indicate that intracranial JVR on TOF MRA is occasionally observed in normal elderly. Therefore, the purpose of this study was to compare the prevalence of intracranial JVR on TOF MRA in patients with TGA and two control groups. Three age- and sex-matched groups of subjects that received MRI and MRA were enrolled. The groups comprised 167 patients with TGA, 167 visitors to the emergency room (ER) and 167 visitors to a health promotion centre (HPC). Intracranial JVR was defined as abnormal venous signals in the inferior petrosal, sigmoid and/or transverse sinuses on TOF MRA. The prevalence of intracranial JVR was assessed across the three groups. Intracranial JVR was seen in seven (4.2 %) TGA patients, eight (4.8 %) ER visitors and three (1.8 %) HPC visitors, respectively. No statistically significant differences were observed among the three groups. TGA patients showed a low prevalence of intracranial JVR on TOF MRA, and no statistical differences were found in comparison with control groups.

Comparison of NIRS, laser Doppler flowmetry, photoplethysmography, and pulse oximetry during vascular occlusion challenges.

PubMed

Abay, T Y; Kyriacou, P A

2016-04-01

Monitoring changes in blood volume, blood flow, and oxygenation in tissues is of vital importance in fields such as reconstructive surgery and trauma medicine. Near infrared spectroscopy (NIRS), laser Doppler (LDF) flowmetry, photoplethysmography (PPG), and pulse oximetry (PO) contribute to such fields due to their safe and noninvasive nature. However, the techniques have been rarely investigated simultaneously or altogether. The aim of this study was to investigate all the techniques simultaneously on healthy subjects during vascular occlusion challenges. Sensors were attached on the forearm (NIRS and LDF) and fingers (PPG and PO) of 19 healthy volunteers. Different degrees of vascular occlusion were induced by inflating a pressure cuff on the upper arm. The responses of tissue oxygenation index (NIRS), tissue haemoglobin index (NIRS), flux (LDF), perfusion index (PPG), and arterial oxygen saturation (PO) have been recorded and analyzed. Moreover, the optical densities were calculated from slow varying dc PPG, in order to distinguish changes in venous blood volumes. The indexes showed significant changes (p  <  0.05) in almost all occlusions, either venous or over-systolic occlusions. However, differentiation between venous and arterial occlusion by LDF may be challenging and the perfusion index (PI) may not be adequate to indicate venous occlusions. Optical densities may be an additional tool to detect venous occlusions by PPG.

Central Venous Occlusion in the Hemodialysis Patient.

PubMed

Krishna, Vinay Narasimha; Eason, Joseph B; Allon, Michael

2016-11-01

Central venous stenosis (CVS) is encountered frequently among hemodialysis patients. Prior ipsilateral central venous catheterization and cardiac rhythm device insertions are common risk factors, but CVS can also occur in the absence of this history. Chronic CVS can cause thrombosis with partial or complete occlusion of the central vein at the site of stenosis. CVS is frequently asymptomatic and identified as an incidental finding during imaging studies. Symptomatic CVS presents most commonly as an upper- or lower-extremity edema ipsilateral to the CVS. Previously unsuspected CVS may become symptomatic after placement of an ipsilateral vascular access. The likelihood of symptomatic CVS may be affected by the central venous catheter (CVC) location; CVC side; duration of CVC dependence; type, location, and blood flow of the ipsilateral access; and extent of collateral veins. Venous angiography is the gold standard for diagnosis. Percutaneous transluminal angioplasty and stent placement can improve the stenosis and alleviate symptoms, but CVS typically recurs frequently, requiring repeated interventions. Refractory symptomatic CVS may require ligation of the ipsilateral vascular access. Because no available treatment option is curative, the goal should be to prevent CVS by minimizing catheters and central vein instrumentation in patients with chronic kidney disease and dialysis patients. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

The gaseous messenger carbon monoxide is released from the eye into the ophthalmic venous blood depending on the intensity of sunlight.

PubMed

Koziorowski, M; Stefańczyk-Krzymowska, S; Tabecka-Lonczyńska, A; Gilun, P; Kamiński, M

2012-01-01

Circadian and seasonal rhythms in daylight affect many physiological processes. In the eye, energy of intense visible light not only initiates a well-studied neural reaction in the retina that modulates the secretory function of the hypothalamus and pineal gland, but also activates the heme oxygenase (HO) to produce carbon monoxide (CO). This study was designed to determine whether the concentration of carbon monoxide (CO) in the ophthalmic venous blood changes depending on the phase of the day and differing extremely light intensity seasons: summer and winter. The concentration of CO in the venous blood flowing out from the nasal cavity, where heme oxygenase (HO) is expressed, but no photoreceptors, was used as a control. Sixteen mature males of a wild boar and pig crossbreed were used for this study. Samples of ophthalmic and nasal venous blood and systemic arterial and venous blood were collected repeatedly for two consecutive days during the longest days of the summer and the shortest days of the winter. The concentrations of CO in blood samples was measured using a standard addition method. During the longest days of the summer the concentration of CO in ophthalmic venous blood averaged 3.32 ± 0.71 and 3.43 ± 0.8 nmol/ml in the morning and afternoon, respectively, and was significantly higher than in the night averaging 0.89 ± 0.12 nmol/ml (p<0.001). During the shortest day of the winter CO concentration in ophthalmic venous blood was 1.11 ± 0.10 and 1.13 ± 0.14 nmol/ml during the light and nocturnal phase, respectively, and did not differ between phases, but was lower than in the light phase of the summer (p<0.01). The CO concentration in the control nasal venous blood did not differ between seasons and day phases and was lower than in ophthalmic venous blood during the summer (p<0.01) and winter (p<0.05). The results indicate that the gaseous messenger carbon monoxide is released from the eye into the ophthalmic venous blood depending on the intensity of sunlight.

Progression of Diabetic Capillary Occlusion: A Model

PubMed Central

Gens, John Scott; Glazier, James A.; Burns, Stephen A.; Gast, Thomas J.

2016-01-01

An explanatory computational model is developed of the contiguous areas of retinal capillary loss which play a large role in diabetic maculapathy and diabetic retinal neovascularization. Strictly random leukocyte mediated capillary occlusion cannot explain the occurrence of large contiguous areas of retinal ischemia. Therefore occlusion of an individual capillary must increase the probability of occlusion of surrounding capillaries. A retinal perifoveal vascular sector as well as a peripheral retinal capillary network and a deleted hexagonal capillary network are modelled using Compucell3D. The perifoveal modelling produces a pattern of spreading capillary loss with associated macular edema. In the peripheral network, spreading ischemia results from the progressive loss of the ladder capillaries which connect peripheral arterioles and venules. System blood flow was elevated in the macular model before a later reduction in flow in cases with progression of capillary occlusions. Simulations differing only in initial vascular network structures but with identical dynamics for oxygen, growth factors and vascular occlusions, replicate key clinical observations of ischemia and macular edema in the posterior pole and ischemia in the retinal periphery. The simulation results also seem consistent with quantitative data on macular blood flow and qualitative data on venous oxygenation. One computational model applied to distinct capillary networks in different retinal regions yielded results comparable to clinical observations in those regions. PMID:27300722

Triple-phase helical computed tomography in dogs with solid splenic masses

PubMed Central

KUTARA, Kenji; SEKI, Mamiko; ISHIGAKI, Kumiko; TESHIMA, Kenji; ISHIKAWA, Chieko; KAGAWA, Yumiko; EDAMURA, Kazuya; NAKAYAMA, Tomohiro; ASANO, Kazushi

2017-01-01

We investigated the utility of triple-phase helical computed tomography (CT) in differentiating between benign and malignant splenic masses in dogs. Forty-two dogs with primary splenic masses underwent triple-phase helical CT scanning (before administration of contrast, and in the arterial phase, portal venous phase, and delayed phase) prior to splenectomy. Tissue specimens were sent for pathological diagnosis; these included hematomas (n=14), nodular hyperplasias (n=12), hemangiosarcomas (n=11), and undifferentiated sarcomas (n=5). The CT findings were compared with the histological findings. Nodular hyperplasia significantly displayed a homogeneous normal enhancement pattern in all phases. Hemangiosarcoma displayed 2 significant contrast-enhancement patterns, including a homogeneous pattern of poor enhancement in all phases, and a heterogeneous remarkable enhancement pattern in the arterial and portal venous phases. Hematoma and undifferentiated sarcoma displayed a heterogeneous normal enhancement pattern in all phases. The contrast-enhanced volumetric ratios of hematoma tended to be greater than those of undifferentiated sarcoma. Our study demonstrated that the characteristic findings on triple-phase helical CT could be useful for the preoperative differentiation of hematoma, nodular hyperplasia, hemangiosarcoma, and undifferentiated sarcoma in dogs. Triple-phase helical CT may be a useful diagnostic tool in dogs with splenic masses. PMID:28993600

Sigmoid sinus cortical plate dehiscence induces pulsatile tinnitus through amplifying sigmoid sinus venous sound.

PubMed

Tian, Shan; Wang, Lizhen; Yang, Jiemeng; Mao, Rui; Liu, Zhaohui; Fan, Yubo

2017-02-08

Sigmoid sinus cortical plate dehiscence (SSCPD) is common in pulsatile tinnitus (PT) patients, and is treated through SSCPD resurfacing surgery in clinic, but the bio-mechanism is not clear as so far. This study aimed to clarify the bio-mechanism of PT sensation induced by SSCPD, and quantify the relationship of cortical plate (CP) thickness and PT sensation intensity. It was hypothesized that SSCPD would induce PT through significantly amplifying sigmoid sinus (SS) venous sound in this study. Finite element (FE) analysis based on radiology data of typical patient was used to verify this hypothesis, and was validated with clinical reports. In cases with different CP thickness, FE simulations of SS venous sound generation and propagation procedure were performed, involving SS venous flow field, vibration response of tissue overlying dehiscence area (including SS vessel wall and CP) and sound propagation in temporal bone air cells. It was shown in results that SS venous sound at tympanic membrane was 56.9dB in SSCPD case and -45.2dB in intact CP case, and was inaudible in all thin CP cases. It was concluded that SSCPD would directly induce PT through significantly amplifying SS venous sound, and thin CP would not be the only pathophysiology of PT. This conclusion would provide a theoretical basis for the design of SSCPD resurfacing surgery for PT patients with SSCPD or thin CP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Measurement of tafenoquine (WR 238605) in human plasma and venous and capillary blood by high-pressure liquid chromatography.

PubMed

Kocisko, D A; Walsh, D S; Eamsila, C; Edstein, M D

2000-04-01

A simple, rapid, and accurate high-pressure liquid chromatographic method with fluorescence detection is described for the measurement of tafenoquine (TQ) (also known as WR 238605) from human plasma and venous and capillary blood. Tafenoquine was measured in plasma and venous blood following protein precipitation. Chromatographic separation was achieved using a Waters S5P Spherisorb phenyl analytical cartridge (150 mm x 4.6 mm I.D., 5 microm particle size) (Waters, Milford, MA, USA) and a mobile phase of 22 mM ammonium acetate, pH 4:acetonitrile (45:55, vol/vol). The flow rate was 1.5 mL/min and the retention times were approximately 3.5 min for WR VIIIAc (internal standard) and approximately 7.8 min for TQ. The interday and intraday coefficients of variation of TQ over a concentration range of 20-1000 ng/mL in plasma were < or =8.4% and in venous blood were < or =9.6%. The mean percent difference between added concentration and obtained concentration was 7.3% in plasma and 8.5% in venous blood over the corresponding concentration range. The limit of quantitation for both fluids was 10 ng/mL. Tafenoquine concentrations were comparable between capillary and venous blood with no significant difference between measurement in both biological fluids. The clinical application of the method was demonstrated by measuring plasma and whole blood concentrations of TQ from participants in a chemosuppression trial of the drug against malaria infections in Thailand.

Neonatal deep white matter venous infarction and liquefaction: a pseudo-abscess lesion.

PubMed

Ruess, Lynne; Dent, Carly M; Tiarks, Hailey J; Yoshida, Michelle A; Rusin, Jerome A

2014-11-01

Deep white matter hemorrhagic venous infarction with subsequent cavitation due to necrosis and liquefaction has been described in neonates and may be associated with infection and meningitis. In our experience, the MRI pattern of these lesions is confused with the pattern seen with cerebral abscesses. The purpose of our study was to characterize the MRI findings of post infarction necrosis and liquefaction after hemorrhagic deep white matter venous infarction in infants and to distinguish these lesions from cerebral abscesses. An institutional review board approved a retrospective review of imaging records to identify all patients with cerebral venous infarction at a children's hospital during a 10-year period. Nine infants had deep white matter hemorrhagic venous infarction with white matter fluid signal cavitary lesions. A diagnosis of cerebral abscess was considered in all. The imaging and laboratory findings in these patients are reviewed and compared to descriptions of abscesses found in the literature. There were six female and three male infants. The mean age at presentation was 20 days (range: 0-90 days), while the corrected age at presentation was less than 30 days for all patients. Seven patients presented with seizures and signs of infection; one infant presented with lethargy and later proved to have protein C deficiency. MRI was performed 0-12 days from presentation in these eight patients. Another patient with known protein C deficiency underwent MRI at 30 days for follow-up of screening US abnormalities. There were a total of 38 deep cerebral white matter fluid signal cavitary lesions: 25 frontal, 9 parietal, 2 temporal, 2 occipital. Larger lesions had dependent debris. All lesions had associated hemorrhage and many lesions had evidence of adjacent small vessel venous thrombosis. Lesions imaged after gadolinium showed peripheral enhancement. Three lesions increased in size on follow-up imaging. Three patients, two with meningitis confirmed via microbiology and one with presumed meningitis by CSF counts, underwent surgical aspiration of a total of six lesions. All specimens were sent for pathology and culture and were negative for microorganisms. Recognizing the MR appearance of cavitary necrosis and liquefaction after deep white matter cerebral venous infarction in neonates can distinguish this entity from cerebral abscess and potentially avoid an unnecessary neurosurgical aspiration procedure.

Is real-time elastography helpful to differentiate acute from subacute deep venous thrombosis? A preliminary study.

PubMed

Aslan, Ahmet; Barutca, Hakan; Ayaz, Ercan; Aslan, Mine; Kocaaslan, Cemal; Inan, Ibrahim; Sahin, Sinan; Yıkılmaz, Ali

2018-02-01

To detect and characterize changes in stiffness of thrombus in patients with acute and subacute deep venous thrombosis (DVT) by using real-time elastography (RTE). Fifty-eight patients with acute or subacute DVT were prospectively evaluated by B-mode sonography (US), color Doppler US (CDUS), and RTE. Two radiologists evaluated the thrombus echogenicity, compressibility, and recanalization of the affected vein, and thrombus stiffness in consensus. The thrombi were classified into 3 groups as soft, intermediate, and hard on RTE images. The final study group consisted of 30 patients with acute DVT, among whom 10 were women (33%), and 19 patients with subacute DVT, among whom 6 were women (32%). The presence of hypoechoic thrombus, incompressible vein, and absence of recanalization on US and CDUS were significantly associated with acute DVT (P < .001 for all variables). The differences in elasticity pattern of the thrombi between acute and subacute DVT were not significant (P = .202). Venous thrombus hardens with age; however, elastography pattern on RTE, in its present form, may not be able to differentiate acute DVT from subacute DVT. © 2017 Wiley Periodicals, Inc.

Observing and understanding arterial and venous circulation differences in a physiology laboratory activity.

PubMed

Altermann, Caroline; Gonçalves, Rithiele; Lara, Marcus Vinícius S; Neves, Ben-Hur S; Mello-Carpes, Pâmela B

2015-12-01

The purpose of the present article is to describe three simple practical experiments that aim to observe and discuss the anatomic and physiological functions and differences between arteries and veins as well as the alterations observed in skin blood flow in different situations. For this activity, students were divided in small groups. In each group, a volunteer is recruited for each experiment. The experiments only require a sphygmomanometer, rubber bands, and a clock and allow students to develop a hypothesis to explain the different responses to the interruption of arterial and venous blood flow. At the end, students prepare a short report, and the results are discussed. This activity allows students to perceive the presence of physiology in their daily lives and helps them to understand the concepts related to the cardiovascular system and hemodynamics. Copyright © 2015 The American Physiological Society.

The effect of ranitidine on the plasma clearance and hepatic extraction of indocyanine green in patients with chronic liver disease.

PubMed Central

Dunk, A A; Jenkins, W J; Burroughs, A K; Walt, R P; Osuafor, T O; Sherlock, S; Mackie, S; Dick, R

1983-01-01

Since hepatic clearance of ICG is reduced by H2-receptor antagonists in normal subjects, it has been suggested that they reduce liver blood flow. We have studied the effect of intravenous ranitidine on ICG clearance in twelve patients with chronic liver disease. Wedged and free hepatic venous pressure were measured before and after intravenous ranitidine in nine of the patients, and the hepatic extraction of ICG was determined in six patients. ICG clearance fell by 22 +/- 11% (s.e. mean) 60 min after ranitidine. In patients in whom ICG clearance fell after intravenous ranitidine the hepatic extraction of ICG was also reduced. There was no significant change in the gradient between wedged and free hepatic venous pressure after ranitidine. It is therefore unlikely that ranitidine lowers liver blood flow. PMID:6137230

Effects of walking in deep venous thrombosis: a new integrated solid and fluid mechanics model.

PubMed

López, Josep M; Fortuny, Gerard; Puigjaner, Dolors; Herrero, Joan; Marimon, Francesc; Garcia-Bennett, Josep

2017-05-01

Deep venous thrombosis (DVT) is a common disease. Large thrombi in venous vessels cause bad blood circulation and pain; and when a blood clot detaches from a vein wall, it causes an embolism whose consequences range from mild to fatal. Walking is recommended to DVT patients as a therapeutical complement. In this study the mechanical effects of walking on a specific patient of DVT were simulated by means of an unprecedented integration of 3 elements: a real geometry, a biomechanical model of body tissues, and a computational fluid dynamics study. A set of computed tomography images of a patient's leg with a thrombus in the popliteal vein was employed to reconstruct a geometry model. Then a biomechanical model was used to compute the new deformed geometry of the vein as a function of the fiber stretch level of the semimembranosus muscle. Finally, a computational fluid dynamics study was performed to compute the blood flow and the wall shear stress (WSS) at the vein and thrombus walls. Calculations showed that either a lengthening or shortening of the semimembranosus muscle led to a decrease of WSS levels up to 10%. Notwithstanding, changes in blood viscosity properties or blood flow rate may easily have a greater impact in WSS. Copyright © 2016 John Wiley & Sons, Ltd.

Near-infrared indocyanine dye permits real-time characterization of both venous and lymphatic circulation

NASA Astrophysics Data System (ADS)

Kurahashi, Toshikazu; Iwatsuki, Katsuyuki; Onishi, Tetsuro; Arai, Tetsuya; Teranishi, Katsunori; Hirata, Hitoshi

2016-08-01

We investigated the optical properties of a near-infrared (NIR) fluorochrome, di-β-cyclodextrin-binding indocyanine derivative (TK-1), and its pharmacokinetic differences with indocyanine green (ICG). TK-1 was designed to have hydrophilic cyclodextrin molecules and, thus, for higher water solubility and smaller particle sizes than the plasma protein-bound ICG. We compared optical properties such as the absorption and fluorescence spectra, quantum yield, and photostability between both dyes in vitro. In addition, we subcutaneously injected a 1 mM solution of TK-1 or ICG into the hind footpad of rats and observed real-time NIR fluorescence intensities in their femoral veins and accompanying lymphatics at the exposed groin site to analyze the dye pharmacokinetics. These optical experiments demonstrated that TK-1 has high water solubility, a low self-aggregation tendency, and high optical and chemical stabilities. Our in vivo imaging showed that TK-1 was transported via peripheral venous flow and lymphatic flow, whereas ICG was drained only through lymphatics. The results of this study showed that lymphatic and venous transport can be differentially regulated and is most likely influenced primarily by particle size, and that TK-1 can enable real-time NIR fluorescence imaging of whole fluids and solute movement via both microvessels and lymphatics, which conventional ICG cannot achieve.

The influence of the position of the oxygen dissociation curve on oxygen-dependent functions of the isolated perfused rat liver. I. Studies at different levels of hypoxic hypoxia.

PubMed

Bakker, J C; Gortmaker, G C; Vrolijk, A C; Offerijns, F G

1976-03-11

Isolated rat livers were perfused with fresh and 2,3-DPG (2,3-diphosphoglycerate)-depleted human erythrocytes at different levels of hypoxia. The mean P50 values of the measured actual oxygen dissociation curves (O.D.C.) were 24.5 and 18 mm Hg. No changes in flow rate and perfusion pressure occurred under the different experimental conditons. It was shown that an advantage or disadvantage of a shift of the O.D.C. depends on the degree of hypoxia, as reflected in the venous PO2. Perfusions with fresh erythrocytes showed higher venous PO2 values during normoxia or moderate hypoxia and lower venous PO2 values at severe hypoxia. A cross-over point was found at a PO2 in the portal vein of 36 mm Hg. The disadvantage of perfusions with fresh erythrocytes at severre hypoxia was also reflected in higher cytoplasmatic and mitochondrial redox levels. Using bile flow rate as an indirect measure for the rate of hydroxylation-dependent O2 consumption a favourable effect of perfusion with fresh erythrocytes was found at a PO2 in the portal vein of 100 and 40 mm Hg.

Monro-Kellie 2.0: The dynamic vascular and venous pathophysiological components of intracranial pressure

PubMed Central

2016-01-01

For 200 years, the ‘closed box’ analogy of intracranial pressure (ICP) has underpinned neurosurgery and neuro-critical care. Cushing conceptualised the Monro-Kellie doctrine stating that a change in blood, brain or CSF volume resulted in reciprocal changes in one or both of the other two. When not possible, attempts to increase a volume further increase ICP. On this doctrine’s “truth or relative untruth” depends many of the critical procedures in the surgery of the central nervous system. However, each volume component may not deserve the equal weighting this static concept implies. The slow production of CSF (0.35 ml/min) is dwarfed by the dynamic blood in and outflow (∼700 ml/min). Neuro-critical care practice focusing on arterial and ICP regulation has been questioned. Failure of venous efferent flow to precisely match arterial afferent flow will yield immediate and dramatic changes in intracranial blood volume and pressure. Interpreting ICP without interrogating its core drivers may be misleading. Multiple clinical conditions and the cerebral effects of altitude and microgravity relate to imbalances in this dynamic rather than ICP per se. This article reviews the Monro-Kellie doctrine, categorises venous outflow limitation conditions, relates physiological mechanisms to clinical conditions and suggests specific management options. PMID:27174995

Monro-Kellie 2.0: The dynamic vascular and venous pathophysiological components of intracranial pressure.

PubMed

Wilson, Mark H

2016-08-01

For 200 years, the 'closed box' analogy of intracranial pressure (ICP) has underpinned neurosurgery and neuro-critical care. Cushing conceptualised the Monro-Kellie doctrine stating that a change in blood, brain or CSF volume resulted in reciprocal changes in one or both of the other two. When not possible, attempts to increase a volume further increase ICP. On this doctrine's "truth or relative untruth" depends many of the critical procedures in the surgery of the central nervous system. However, each volume component may not deserve the equal weighting this static concept implies. The slow production of CSF (0.35 ml/min) is dwarfed by the dynamic blood in and outflow (∼700 ml/min). Neuro-critical care practice focusing on arterial and ICP regulation has been questioned. Failure of venous efferent flow to precisely match arterial afferent flow will yield immediate and dramatic changes in intracranial blood volume and pressure. Interpreting ICP without interrogating its core drivers may be misleading. Multiple clinical conditions and the cerebral effects of altitude and microgravity relate to imbalances in this dynamic rather than ICP per se. This article reviews the Monro-Kellie doctrine, categorises venous outflow limitation conditions, relates physiological mechanisms to clinical conditions and suggests specific management options. © The Author(s) 2016.

Tissue perfusion during normovolemic hemodilution investigated by a hydraulic model of the cardiovascular system.

PubMed

Mirhashemi, S; Messmer, K; Intaglietta, M

1987-01-01

Normovolemic hemodilution on a whole body basis is studied by means of a steady flow, hydraulic analogue simulation of the cardiovascular system, based on the Casson's model and current hemodynamic and rheological data. The vasculature is divided into serially connected compartments whose hydraulic resistance is characterized by the average diameter, length, number of vessels, and the corresponding rheological properties of blood formulated by Dintenfass (1971) and Lipowsky et al. (1980). This model computes the pressure distributions in all compartments, where the calculated venous pressure modulates the cardiac function according to the Starling mechanism for cardiac performance. The alterations of flow induced by the action of the heart are added to the effects due to changes in peripheral vascular resistance as a result of hematocrit variation. This model shows that when the response of heart to the changes of venous pressure is impaired, the maximum oxygen carrying capacity occurs at 40% hematocrit (H) where it is 1% higher than normal hematocrit (H = 44%). The normal cardiac response to the changes of venous pressure, causes the maximum oxygen carrying capacity to occur at 32% H where it is 12% greater than that at normal hematocrit. Mean arteriolar pressure and capillary pressure increase while venular pressure is slightly reduced during normovolemic hemodilution.

The Oscillating Component of the Internal Jugular Vein Flow: The Overlooked Element of Cerebral Circulation

PubMed Central

Sisini, Francesco; Toro, Eleuterio; Gambaccini, Mauro; Zamboni, Paolo

2015-01-01

The jugular venous pulse (JVP) provides valuable information about cardiac haemodynamics and filling pressures and is an indirect estimate of the central venous pressure (CVP). Recently it has been proven that JVP can be obtained by measuring the cross-sectional area (CSA) of the IJV on each sonogram of an ultrasound B-mode sonogram sequence. It has also been proven that during its pulsation the IJV is distended and hence that the pressure gradient drives the IJV haemodynamics. If this is true, then it will imply the following: (i) the blood velocity in the IJV is a periodic function of the time with period equal to the cardiac period and (ii) the instantaneous blood velocity is given by a time function that can be derived from a flow-dynamics theory that uses the instantaneous pressure gradient as a parameter. The aim of the present study is to confirm the hypothesis that JVP regulates the IJV blood flow and that pressure waves are transmitted from the heart toward the brain through the IJV wall. PMID:26783380

Surgical management of venous malformations.

PubMed

Loose, D A

2007-01-01

Among vascular malformations, the predominantly venous malformations represent the majority of cases. They form a clinical entity and therefore need clear concepts concerning diagnosis and treatment. This paper presents an overview of contemporary classification as well as tactics and techniques of treatment. According to the Hamburg Classification, predominantly venous malformations are categorized into truncular and extratruncular forms, with truncular forms distinguished as obstructions and dilations, and extratruncular forms as limited or infiltrating. The tactics of treatment represent surgical and non-surgical methods or combined techniques. Surgical approaches utilize different tactics and techniques that are adopted based on the pathologic form and type of the malformation: (I) operation to reduce the haemodynamic activity of the malformation; (II) operation to eliminate the malformation; and (III) reconstructive operation. As for (I), a type of a tactic is the operation to derive the venous flow. In (II), the total or partial removal of the venous malformation is demonstrated subdivided into three different techniques. In this way, the infiltrating as well as the limited forms can be treated. An additional technique is dedicated to the treatment of a marginal vein. Approach (III) involves the treatment of venous aneurysms, where a variety of techniques have been successful. Long-term follow-up demonstrates positive results in 91% of the cases. Congenital predominantly venous malformations should be treated according to the principles developed during the past decades in vascular surgery, interventional treatment and multidisciplinary treatment. The days of predominantly conservative treatment should be relegated to the past. Special skills and experiences are necessary to carry out appropriate surgical strategy, and the required operative techniques should be dictated by the location and type of malformation and associated findings.

Vascular patterns in the heads of crocodilians: blood vessels and sites of thermal exchange.

PubMed

Porter, William Ruger; Sedlmayr, Jayc C; Witmer, Lawrence M

2016-12-01

Extant crocodilians are a highly apomorphic archosaur clade that is ectothermic, yet often achieve large body sizes that can be subject to higher heat loads. Therefore, the anatomical and physiological roles that blood vessels play in crocodilian thermoregulation need further investigation to better understand how crocodilians establish and maintain cephalic temperatures and regulate neurosensory tissue temperatures during basking and normal activities. The cephalic vascular anatomy of extant crocodilians, particularly American alligator (Alligator mississippiensis) was investigated using a differential-contrast, dual-vascular injection technique and high resolution X-ray micro-computed tomography (μCT). Blood vessels were digitally isolated to create representations of vascular pathways. The specimens were then dissected to confirm CT results. Sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in evaporative cooling and cephalic thermoregulation in other diapsids. Blood vessels to and from sites of thermal exchange were studied to detect conserved vascular patterns and to assess their ability to deliver cooled blood to neurosensory tissues. Within the orbital region, both the arteries and veins demonstrated consistent branching patterns, with the supraorbital, infraorbital, and ophthalmotemporal vessels supplying and draining the orbit. The venous drainage of the orbital region showed connections to the dural sinuses via the orbital veins and cavernous sinus. The palatal region demonstrated a vast plexus that comprised both arteries and veins. The most direct route of venous drainage of the palatal plexus was through the palatomaxillary veins, essentially bypassing neurosensory tissues. Anastomotic connections with the nasal region, however, may provide an alternative route for palatal venous blood to reach neurosensory tissues. The nasal region in crocodilians is probably the most prominent site of thermal exchange, as it offers a substantial surface area and is completely surrounded by blood vessels. The venous drainage routes from the nasal region offer routes directly to the dural venous sinuses and the orbit, offering evidence of the potential to directly affect neurosensory tissue temperatures. The evolutionary history of crocodilians is complex, with large-bodied, terrestrial, and possibly endothermic taxa that may have had to deal with thermal loads that likely provided the anatomical building-blocks for such an extensive vascularization of sites of thermal exchange. A clear understanding of the physiological abilities and the role of blood vessels in the thermoregulation of crocodilians neurosensory tissues is not available but vascular anatomical patterns of crocodilian sites of thermal exchange indicate possible physiological abilities that may be more sophisticated than in other extant diapsids. © 2016 Anatomical Society.

Extracorporeal gas exchange with the DeltaStream rotary blood pump in experimental lung injury.

PubMed

Dembinski, Rolf; Kopp, Rüdger; Henzler, Dietrich; Hochhausen, Nadine; Oslender, Nicole; Max, Martin; Rossaint, Rolf; Kuhlen, Ralf

2003-06-01

In most severe cases of the acute respiratory distress syndrome, veno-venous extracorporeal membrane oxygenation (ECMO) can be used to facilitate gas exchange. However, the clinical use is limited due to the size and the concomitant risk of severe adverse events of conventionally-used centrifugal blood pumps with high extracorporeal blood volumes. The DeltaStream blood pump is a small-sized rotary blood pump that may reduce extracorporeal blood volume, foreign surfaces, contact activation of the coagulation system, and blood trauma. The aim of the present study was to test the safety and efficacy of the DeltaStream pump for ECMO in animals with normal lung function and experimental acute lung injury (ALI). Therefore, veno-venous ECMO was performed for 6 hours in mechanically ventilated pigs with normal lung function (n=6) and with ALI induced by repeated lung lavage (n=6) with a blood flow of 30% of the cardiac output. Gas flow with a FiO2 of 1.0 was set to equal blood flow. With a mean activated clotting time of 121 +/- 22 s, no circulatory impairment or thrombus formation was revealed during ECMO. Furthermore, free plasma Hb did not increase. In controls, hemodynamics and gas exchange remained unchanged. In animals with ALI, hemodynamics remained stable and gas transfer across the extracorporeal oxygenators was optimal, but only in 2 animals was a marked increase in PaO2 observed. CO2 removal was efficacious in all animals. We concluded that the DeltaStream blood pump may be used for veno-venous ECMO without major blood damage or hemodynamic impairment.

Central retinal vein occlusion with cilioretinal infarction from branch flow exclusion and choroidal arterial steal.

PubMed

McLeod, David

2009-01-01

The first definitive study of retinal vein occlusion complicated by infarction within the territory of one or more cilioretinal arteries was published in 1976. Many individual cases and further case series have been reported in the interim, but the nature of the interrelationship is still under debate. A review was undertaken of the relevant clinical and fundus fluorescein angiographic characteristics of this combined retinal vascular disorder together with the pathophysiological mechanisms currently presented in the literature to explain their association. Scientific publications up to 2008 were evaluated by one of the authors of the original report. There are broad similarities between publications in their descriptions of the clinical features, but significant differences of detail and interpretation are also evident. Most of the mechanisms so far proposed to account for cilioretinal infarction after central or hemisphere retinal vein occlusion do not withstand critical scrutiny. Two related hypotheses are expounded that appear to satisfactorily elucidate this interrelationship -- branch flow exclusion and branch flow diversion (otherwise termed "choroidal arterial steal"). In eyes with a cilioretinal supply, the probability that cilioretinal infarction will complicate retinal vein occlusion increases with increasing severity of venous obstruction and the more distally the cilioretinal artery arises from the posterior ciliary arterial tree. A distal branch point also facilitates observation of dye front reciprocation within the artery. Indicators of the degree of venous obstruction that may be necessary to instigate cilioretinal infarction include very prolonged dye transit times in the central retinal circulation, exaggerated venous cyanosis and tortuosity, perivenous cotton-wool sentinels, and macular perivenular whitening.

Temporal patterns of blood volume, hemodynamics, and oxygen transport in pathogenesis and therapy of postoperative adult respiratory distress syndrome.

PubMed

Shoemaker, W C; Appel, P L; Bishop, M H

1993-11-01

Time relationships of physiologic patterns that are relevant to the pathogenesis of adult respiratory distress syndrome (ARDS) have not been well studied. The purpose of this review is to summarize the temporal relationship of blood volume, hemodynamics, and oxygen transport patterns occurring in postoperative patients before and after ARDS in order to develop a more complete mechanistic evaluation of its pathophysiology and to propose more rational therapeutic strategies. The data indicate that hypovolemia, reduced or uneven blood flow, inadequate delivery of oxygen, and insufficient consumption of oxygen precede the appearance of ARDS and are the primary precipitating physiologic events. This is contrary to conventional thinking which emphasizes capillary leak and fluid overload as the primary problems. The conventional approach also ignores events antecedent to ARDS that produce hypoxia of the lung tissue, result in pulmonary vasoconstriction, and increased pulmonary venous admixture (shunt). Therapy to prevent or rapidly treat these antecedent events has been shown to prevent or attenuate postoperative and posttraumatic ARDS. Various mediators such as interleukin (IL)-1, IL-6, and IL-8 and tumor necrosis factor as measured by plasma concentrations do not precede diagnostic criteria of ARDS, but may accelerate and augment the disorder as it is occurring.

Hepatic encephalopathy caused by congenital extrahepatic portosystemic venous shunt.

PubMed

Ishii, Y; Inagaki, Y; Hirai, K; Aoki, T

2000-01-01

Congenital portosystemic venous shunt is a relatively rare disease. Recently, a 60-year-old woman was admitted to our hospital for hepatic encephalopathy caused by congenital extrahepatic portocaval shunt. She had been in good health until the onset of this event, with no liver damage and no experience of abdominal surgery or history of abdominal trauma. In May 1993, hepatic encephalopathy manifested suddenly, with the chief complaint of orthostatic disturbance. Although conservative treatment was administered during the subsequent 5 years, on admission, liver damage and slight splenomegaly were shown, for which complete resection of the shunt vessel and splenectomy were performed. Postoperatively, the patient's symptoms have been alleviated. Hepatic encephalopathy caused by congenital portosystemic venous shunt requires long-term conservative treatment, and the patient's quality of life is reduced. For this reason, surgical intervention or embolization with interventional radiology should be considered, and the maintenance of hepatic blood flow should also be considered.

Combination therapy using PSE and TIO ameliorates hepatic encephalopathy due to intrahepatic portosystemic venous shunt in idiopathic portal hypertension

PubMed Central

Kojima, Seiichiro; Ito, Hiroyuki; Takashimizu, Shinji; Ichikawa, Hitoshi; Matsumoto, Tomohiro; Hasebe, Terumitsu

2016-01-01

A 64-year-old woman treated for anemia and ascites exhibited hepatic encephalopathy. Abdominal ultrasonography and computed tomography (CT) showed communication between the portal vein and the middle hepatic vein, indicating an intrahepatic portosystemic venous shunt (PSS). Since hepatic encephalopathy of the patient was resistant to medical treatment, interventional radiology was performed for the treatment of shunt obliteration. Hepatic venography showed anastomosis between the hepatic vein branches, supporting the diagnosis of idiopathic portal hypertension (IPH). To minimize the increase in portal vein pressure after shunt obliteration, partial splenic artery embolization (PSE) was first performed to reduce portal vein blood flow. Transileocolic venous obliteration (TIO) was then performed, and intrahepatic PSS was successfully obliterated using coils with n-butyl-2-cyanoacrylate (NBCA). In the present case, hepatic encephalopathy due to intrahepatic PSS in the patient with IPH was successfully treated by combination therapy using PSE and TIO. PMID:27651930

A new veno-venous bypass type for ex-vivo liver resection in dogs.

PubMed

Lei, Peng; Liu, Shi-Qi; Cui, Xiao-Hai; Lv, Yi; Zhao, Ge; Li, Jian-Hui

2013-08-01

Ex-vivo liver resection is a procedure in which the liver is completely removed, perfused and after bench surgery, the liver is autotransplanted to the original site. Ex-vivo liver resection is an important treatment for unresectable liver tumors. This surgical procedure requires long operation time, during which blood flow must be carefully maintained to avoid venous congestion. An effective veno-venous bypass (VVB) may meet this requirement. The present study was to test our new designed VVB device which comprised one heparinized polyvinylchloride tube and three magnetic rings. The efficacy of this device was tested in five dogs. A VVB was established in 6-10 minutes. There was no leakage during the procedure. Hemodynamics was stable at anhepatic phase, which indicated that the bypass was successful. This newly-developed VVB device maintained circulation stability during ex-vivo liver resection in our dog model and thus, this VVB device significantly shortened the operation time.

Wall Shear Stress Restoration in Dialysis Patient's Venous Stenosis: Elucidation via 3D CFD and Shape Optimization

NASA Astrophysics Data System (ADS)

Mahmoudzadeh Akherat, S. M. Javid; Cassel, Kevin; Hammes, Mary; Boghosian, Michael; Illinois Institute of Technology Team; University of Chicago Team

2016-11-01

Venous stenosis developed after the growth of excessive neointimal hyperplasia (NH) in chronic dialysis treatment is a major cause of mortality in renal failure patients. It has been hypothesized that the low wall shear stress (WSS) triggers an adaptive response in patients' venous system that through the growth of neointimal hyperplastic lesions restores WSS and transmural pressure, which also regulates the blood flow rate back to physiologically acceptable values which is violated by dialysis treatment. A strong coupling of three-dimensional CFD and shape optimization analyses were exploited to elucidate and forecast this adaptive response which correlates very well topographically with patient-specific clinical data. Based on the framework developed, a medical protocol is suggested to predict and prevent dialysis treatment failure in clinical practice. Supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (R01 DK90769).

Hemodynamic analysis and treatment of an enlarging extrahepatic portal aneurysm: report of a case.

PubMed

Iimuro, Yuji; Suzumura, Kazuhiro; Ohashi, Koichiro; Tanaka, Hironori; Iijima, Hiroko; Nishiguchi, Shuhei; Hao, Hiroyuki; Fujimoto, Jiro

2015-03-01

Aneurysms in the portal venous system are relatively rare. We report the case of an extrahepatic portal venous aneurysm, detected incidentally by ultrasonography. The patient, a 75-year-old woman, was initially observed over 18 months, during which time, the aneurysm grew from 36 mm × 32 mm to 51 mm × 37 mm in size, without symptoms. Hemodynamic analysis employing computational flow dynamics technique showed obvious turbulence in the aneurysm, and the wall shear stress (WSS) against that part of the aneurysmal wall was greater than in other sites. To prevent complications such as spontaneous rupture and portal vein thrombosis, the aneurysm was resected, with reconstruction of the portal trunk. While careful follow-up is sufficient for most portal venous aneurysms, its enlargement could indicate possible spontaneous rupture. The increased WSS against part of the aneurysmal wall most likely accounts for the aneurysm enlargement in this case.

Renal responses to central vascular expansion are suppressed at night in conscious primates

NASA Technical Reports Server (NTRS)

Kass, D. A.; Sulzman, F. M.; Fuller, C. A.; Moore-Ede, M. C.

1980-01-01

The renal and hemodynamic responses of squirrel monkeys to central vascular volume expansion induced by lower body positive pressure (LBPP) during the day and night are investigated. Twelve unanesthetized animals trained to sit in a metabolism chair in which they were restrained only at the waist by a partition separating upper and lower body chambers were subjected to 4 h of continuous LBPP during the day and night, and hemodynamic, urinary and drinking data were monitored. LBPP during day and night is found to induce similar increases in central venous pressure, rises in heart rate and elevations in mean arterial blood pressure. However, although daytime LBPP induced a significant increase in urine flow and sodium excretion, a marked nocturnal inhibition of the renal response to LBPP is observed. Analysis of the time course and circadian regulation patterns of the urinary responses suggests that several separate efferent control pathways are involved.

The anatomy of the cardiac veins in mice

PubMed Central

Ciszek, Bogdan; Skubiszewska, Daria; Ratajska, Anna

2007-01-01

Although the cardiac coronary system in mice has been the studied in detail by many research laboratories, knowledge of the cardiac veins remains poor. This is because of the difficulty in marking the venous system with a technique that would allow visualization of these large vessels with thin walls. Here we present the visualization of the coronary venous system by perfusion of latex dye through the right caudal vein. Latex injected intravenously does not penetrate into the capillary system. Murine cardiac veins consist of several principal branches (with large diameters), the distal parts of which are located in the subepicardium. We have described the major branches of the left atrial veins, the vein of the left ventricle, the caudal veins, the vein of the right ventricle and the conal veins forming the conal venous circle or the prepulmonary conal venous arch running around the conus of the right ventricle. The venous system of the heart drains the blood to the coronary sinus (the left cranial caval vein) to the right atrium or to the right cranial caval vein. Systemic veins such as the left cranial caval, the right cranial caval and the caudal vein open to the right atrium. Knowledge of cardiac vein location may help to elucidate abnormal vein patterns in certain genetic malformations. PMID:17553104

Maximal venous outflow velocity: an index for iliac vein obstruction.

PubMed

Jones, T Matthew; Cassada, David C; Heidel, R Eric; Grandas, Oscar G; Stevens, Scott L; Freeman, Michael B; Edmondson, James D; Goldman, Mitchell H

2012-11-01

Leg swelling is a common cause for vascular surgical evaluation, and iliocaval obstruction due to May-Thurner syndrome (MTS) can be difficult to diagnose. Physical examination and planar radiographic imaging give anatomic information but may miss the fundamental pathophysiology of MTS. Similarly, duplex ultrasonographic examination of the legs gives little information about central impedance of venous return above the inguinal ligament. We have modified the technique of duplex ultrasonography to evaluate the flow characteristics of the leg after tourniquet-induced venous engorgement, with the objective of revealing iliocaval obstruction characteristic of MTS. Twelve patients with signs and symptoms of MTS were compared with healthy control subjects for duplex-derived maximal venous outflow velocity (MVOV) after tourniquet-induced venous engorgement of the leg. The data for healthy control subjects were obtained from a previous study of asymptomatic volunteers using the same MVOV maneuvers. The tourniquet-induced venous engorgement mimics that caused during vigorous exercise. A right-to-left ratio of MVOV was generated for patient comparisons. Patients with clinical evidence of MTS had a mean right-to-left MVOV ratio of 2.0, asymptomatic control subjects had a mean ratio of 1.3, and MTS patients who had undergone endovascular treatment had a poststent mean ratio of 1.2 (P = 0.011). Interestingly, computed tomography and magnetic resonance imaging results, when available, were interpreted as positive in only 53% of the patients with MTS according to both our MVOV criteria and confirmatory venography. After intervention, the right-to-left MVOV ratio in the MTS patients was found to be reduced similar to asymptomatic control subjects, indicating a relief of central venous obstruction by stenting the compressive MTS anatomy. Duplex-derived MVOV measurements are helpful for detection of iliocaval venous obstruction, such as MTS. Right-to-left MVOV ratios and postengorgement spectral analysis are helpful adjuncts to duplex imaging for leg swelling. The MVOV maneuvers are well tolerated by patients and yields physiological data regarding central venous obstruction that computed tomography and magnetic resonance imaging fail to detect. Copyright © 2012 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.

A novel pump-driven veno-venous gas exchange system during extracorporeal CO2-removal.

PubMed

Hermann, Alexander; Riss, Katharina; Schellongowski, Peter; Bojic, Andja; Wohlfarth, Philipp; Robak, Oliver; Sperr, Wolfgang R; Staudinger, Thomas

2015-10-01

Pump-driven veno-venous extracorporeal CO2-removal (ECCO2-R) increasingly takes root in hypercapnic lung failure to minimize ventilation invasiveness or to avoid intubation. A recently developed device (iLA activve(®), Novalung, Germany) allows effective decarboxylation via a 22 French double lumen cannula. To assess determinants of gas exchange, we prospectively evaluated the performance of ECCO2-R in ten patients receiving iLA activve(®) due to hypercapnic respiratory failure. Sweep gas flow was increased in steps from 1 to 14 L/min at constant blood flow (phase 1). Similarly, blood flow was gradually increased at constant sweep gas flow (phase 2). At each step gas transfer via the membrane as well as arterial blood gas samples were analyzed. During phase 1, we observed a significant increase in CO2 transfer together with a decrease in PaCO2 levels from a median of 66 mmHg (range 46-85) to 49 (31-65) mmHg from 1 to 14 L/min sweep gas flow (p < 0.0001), while arterial oxygenation deteriorated with high sweep gas flow rates. During phase 2, oxygen transfer significantly increased leading to an increase in PaO2 from 67 (49-87) at 0.5 L/min to 117 (66-305) mmHg at 2.0 L/min (p < 0.0001). Higher blood flows also significantly enhanced decarboxylation (p < 0.0001). Increasing sweep gas flow results in effective CO2-removal, which can be further reinforced by raising blood flow. The clinically relevant oxygenation effect in this setting could broaden the range of indications of the system and help to set up an individually tailored configuration.

Use of an Intravascular Fluorescent Continuous Glucose Sensor in ICU Patients.

PubMed

Strasma, Paul J; Finfer, Simon; Flower, Oliver; Hipszer, Brian; Kosiborod, Mikhail; Macken, Lewis; Sechterberger, Marjolein; van der Voort, Peter H J; DeVries, J Hans; Joseph, Jeffrey I

2015-07-01

Hyperglycemia and hypoglycemia are associated with adverse clinical outcomes in intensive care patients. In product development studies at 4 ICUs, the safety and performance of an intravascular continuous glucose monitoring (IV-CGM) system was evaluated in 70 postsurgical patients. The GluCath System (GluMetrics, Inc) used a quenched chemical fluorescence mechanism to optically measure blood glucose when deployed via a radial artery catheter or directly into a peripheral vein. Periodic ultrasound assessed blood flow and thrombus formation. Patient glucose levels were managed according to the standard of care and existing protocols at each site. Reference blood samples were acquired hourly and compared against prospectively calibrated sensor results. In all, 63 arterial sensors and 9 venous sensors were deployed in 70 patients. Arterial sensors did not interfere with invasive blood pressure monitoring, sampling or other aspects of patient care. A majority of venous sensors (66%) exhibited thrombus on ultrasound. In all, 89.4% (1383/1547) of arterial and 72.2% (182/252) of venous measurements met ISO15197:2003 criteria (within 20%), and 72.7% (1124/1547) of arterial and 56.3% (142/252) of venous measurements met CLSI POCT 12-A3 criteria (within 12.5%). The aggregate mean absolute relative difference (MARD) between the sensors and the reference was 9.6% for arterial and 14.2% for venous sensors. The GluCath System exhibited acceptable accuracy when deployed in a radial artery for up to 48 hours in ICU patients after elective cardiac surgery. Accuracy of venous deployment was substantially lower with significant rates of intravascular thrombus observed using ultrasound. © 2015 Diabetes Technology Society.

Imaging the Effects of Oxygen Saturation Changes in Voluntary Apnea and Hyperventilation on Susceptibility-Weighted Imaging

PubMed Central

Chang, K.; Barnes, S.; Haacke, E.M.; Grossman, R.I.; Ge, Y.

2014-01-01

BACKGROUND AND PURPOSE Cerebrovascular oxygenation changes during respiratory challenges have clinically important implications for brain function, including cerebral autoregulation and the rate of brain metabolism. SWI is sensitive to venous oxygenation level by exploitation of the magnetic susceptibility of deoxygenated blood. We assessed cerebral venous blood oxygenation changes during simple voluntary breath-holding (apnea) and hyperventilation by use of SWI at 3T. MATERIALS AND METHODS We performed SWI scans (3T; acquisition time of 1 minute, 28 seconds; centered on the anterior commissure and the posterior commissure) on 10 healthy male volunteers during baseline breathing as well as during simple voluntary hyperventilation and apnea challenges. The hyperventilation and apnea tasks were separated by a 5-minute resting period. SWI venograms were generated, and the signal changes on SWI before and after the respiratory stress tasks were compared by means of a paired Student t test. RESULTS Changes in venous vasculature visibility caused by the respiratory challenges were directly visualized on the SWI venograms. The venogram segmentation results showed that voluntary apnea decreased the mean venous blood voxel number by 1.6% (P<.0001), and hyperventilation increased the mean venous blood voxel number by 2.7% (P<.0001). These results can be explained by blood CO2 changes secondary to the respiratory challenges, which can alter cerebrovascular tone and cerebral blood flow and ultimately affect venous oxygen levels. CONCLUSIONS These results highlight the sensitivity of SWI to simple and noninvasive respiratory challenges and its potential utility in assessing cerebral hemodynamics and vasomotor responses. PMID:24371029

Imaging the effects of oxygen saturation changes in voluntary apnea and hyperventilation on susceptibility-weighted imaging.

PubMed

Chang, K; Barnes, S; Haacke, E M; Grossman, R I; Ge, Y

2014-06-01

Cerebrovascular oxygenation changes during respiratory challenges have clinically important implications for brain function, including cerebral autoregulation and the rate of brain metabolism. SWI is sensitive to venous oxygenation level by exploitation of the magnetic susceptibility of deoxygenated blood. We assessed cerebral venous blood oxygenation changes during simple voluntary breath-holding (apnea) and hyperventilation by use of SWI at 3T. We performed SWI scans (3T; acquisition time of 1 minute, 28 seconds; centered on the anterior commissure and the posterior commissure) on 10 healthy male volunteers during baseline breathing as well as during simple voluntary hyperventilation and apnea challenges. The hyperventilation and apnea tasks were separated by a 5-minute resting period. SWI venograms were generated, and the signal changes on SWI before and after the respiratory stress tasks were compared by means of a paired Student t test. Changes in venous vasculature visibility caused by the respiratory challenges were directly visualized on the SWI venograms. The venogram segmentation results showed that voluntary apnea decreased the mean venous blood voxel number by 1.6% (P < .0001), and hyperventilation increased the mean venous blood voxel number by 2.7% (P < .0001). These results can be explained by blood CO2 changes secondary to the respiratory challenges, which can alter cerebrovascular tone and cerebral blood flow and ultimately affect venous oxygen levels. These results highlight the sensitivity of SWI to simple and noninvasive respiratory challenges and its potential utility in assessing cerebral hemodynamics and vasomotor responses. © 2014 by American Journal of Neuroradiology.

Long-term results of small-diameter proximal splenorenal venous shunt: A retrospective study

PubMed Central

Chen, Hao; Yang, Wei-Ping; Yan, Ji-Qi; Li, Qin-Yu; Ma, Di; Li, Hong-Wei

2011-01-01

AIM: To investigate recurrent variceal hemorrhage and long-term survival rates of patients treated with partial proximal splenorenal venous shunt. METHODS: Patients with variceal hemorrhage who were treated with small-diameter proximal splenorenal venous shunt in Ruijin Hospital between 1996 and 2009 were included in this study. Shunt diameter was determined before operation using Duplex Doppler ultrasonography. Peri-operative and long-term results in term of rehemorrhage, encephalopathy and mortality were followed up. RESULTS: Ninety-eight patients with Child A and B variceal hemorrhage received small-diameter proximal splenorenal venous shunt with a diameter of 7-10 mm. After operation, the patients’ mean free portal pressure (P < 0.01) and the flow rate of main portal vein (P < 0.01) decreased significantly compared with that before operation. The rates of rebleeding and mortality were 6.12% (6 cases) and 2.04% (2 cases), respectively. Ninety-one patients were followed up for 7 mo-14 years (median, 48.57 mo). Long-term rates of rehemorrhage and encephalopathy were 4.40% (4 cases) and 3.30% (3 cases), respectively. Thirteen patients (14.29%) died mainly due to progressive hepatic dysfunction. Five- and ten-year survival rates were 82.12% and 71.24%, respectively. CONCLUSION: Small-diameter proximal splenorenal venous shunt affords protection against variceal rehemorrhage with a low occurrence of encephalopathy in patients with normal liver function. PMID:21876638

Cardiac resynchronization therapy with special focus on patency of coronary sinus and its branches: conceptual viewpoint and semi-theoretical considerations on lead-induced obstruction.

PubMed

Stirbys, Petras

2006-01-01

Cardiac resynchronization therapy appears to be useful for patients with severe chronic congestive heart failure. However, many questions still arise concerning the effectiveness of this kind of therapy since hemodynamic improvement is not observed in all patients. Heterogeneity of conclusions reported by several multicenter clinical trials and prominent experts demonstrates that many uncertainties related to cardiac resynchronization therapy still exist. We tried to reveal some inadequacies in clinical results by focusing on cardiac venous blood return which is likely complicated by the presence of lead inside the coronary sinus and its branches. Downstream traversing lead may occlude (partially or completely) the ostia of minor tributaries and target vein of lead final positioning. Thrombosis may also be incited within the coronary sinus itself. Remaining lumen predetermined by the lead body and subsequent thrombosis may be insufficient to provide adequate blood flow. Resulting detrimental venous return presumably may slightly depress myocardial contractility which may be significant in very sensitive group of patients assigned to the New York Heart Association class III or IV. Cardiac venous blood pumping conditions (or venous drainage) are likely also complicated by abnormal activation of left ventricle. The contributory role of these two subtle causes unfavorably influencing venous drainage is still unknown. It may be treated as a hypothetical attempt to find the clue and needs future studies for verification.

Myeloid-related protein-14 regulates deep vein thrombosis

PubMed Central

Wang, Yunmei; Gao, Huiyun; Kessinger, Chase W.; Schmaier, Alvin; Jaffer, Farouc A.; Simon, Daniel I.

2017-01-01

Using transcriptional profiling of platelets from patients presenting with acute myocardial infarction, we identified myeloid-related protein-14 (MRP-14, also known as S100A9) as an acute myocardial infarction gene and reported that platelet MRP-14 binding to platelet CD36 regulates arterial thrombosis. However, whether MRP-14 plays a role in venous thrombosis is unknown. We subjected WT and Mrp-14–deficient (Mrp-14-/-) mice to experimental models of deep vein thrombosis (DVT) by stasis ligation or partial flow restriction (stenosis) of the inferior vena cava. Thrombus weight in response to stasis ligation or stenosis was reduced significantly in Mrp-14-/- mice compared with WT mice. The adoptive transfer of WT neutrophils or platelets, or the infusion of recombinant MRP-8/14, into Mrp-14-/- mice rescued the venous thrombosis defect in Mrp-14-/- mice, indicating that neutrophil- and platelet-derived MRP-14 directly regulate venous thrombogenesis. Stimulation of neutrophils with MRP-14 induced neutrophil extracellular trap (NET) formation, and NETs were reduced in venous thrombi harvested from Mrp-14-/- mice and in Mrp-14-/- neutrophils stimulated with ionomycin. Given prior evidence that MRP-14 also regulates arterial thrombosis, but not hemostasis (i.e., reduced bleeding risk), MRP-14 appears to be a particularly attractive molecular target for treating thrombotic cardiovascular diseases, including myocardial infarction, stroke, and venous thromboembolism. PMID:28570273

Prevalence of venous obstruction in permanent endovenous pacing in newborns and infants: follow-up study.

PubMed

Stojanov, Petar; Vranes, Mile; Velimirovic, Dusan; Zivkovic, Mirjana; Kocica, Mladen J; Davidovic, Lazar; Neskovic, Voislava; Stajevic, Mila

2005-05-01

We examined the prevalence of venous obstruction in 12 newborns and infants with permanent endovenous ventricular pacing, clinically, and by ultrasonographic assessment of hemodynamics (spontaneity, phasicity, velocity, and turbulence of flow) and morphologic parameters (compressibility, wall thickness, and thrombus presence). All implantations of single ventricular unipolar endovenous steroid leads, were performed via cephalic vein, and pacemakers were placed in subcutaneous pocket in right prepectoral region. After the vascular surgeon has carefully examined all children for presence of venous collaterals in the chest wall, morphologic and hemodynamic parameters of the subclavian, axillary, and internal jugular veins, were assessed by linear-array color Doppler. Lead capacity (LC) was calculated for each patient. Mean age of patients at implant was 6.2 months (range 1 day-12 months), mean weight 6.5 kg (range 2.25-10 kg), and mean height 60.9 cm (range 48-78 cm). Mean LC was 1.99 (range 1.14-3.07). Total follow-up was 1023 and mean follow-up 85.2 pacing months (range 3-156). No clinical signs of venous obstruction were observed. Mild stenosis (20%) of subclavian vein was found by color Doppler in 2/12 patients. Both had adequate lead diameter for body surface. Permanent endovenous pacing is a feasible procedure, even in children of body weight less than 10 kg, with quite acceptable impact on venous system patency.

Mechanism of autoregulation in the intact kidney.

DOT National Transportation Integrated Search

1963-12-01

The mechanism of renal autoregulation is unclear. The subject of the present investigation is the mechanism of autoregulation of blood flow in the intact kidney. The left kidney of the anesthetized dog was exposed via a flank approach. Renal venous o...

Intermittent hemodialysis is superior to continuous veno-venous hemodialysis/hemodiafiltration to eliminate methanol and formate during treatment for methanol poisoning

PubMed Central

Zakharov, Sergey; Pelclova, Daniela; Navratil, Tomas; Belacek, Jaromir; Kurcova, Ivana; Komzak, Ondrej; Salek, Tomas; Latta, Jiri; Turek, Radovan; Bocek, Robert; Kucera, Cyril; Hubacek, Jaroslav A; Fenclova, Zdenka; Petrik, Vit; Cermak, Martin; Hovda, Knut Erik

2014-01-01

During an outbreak of methanol poisonings in the Czech Republic in 2012, we were able to study methanol and formate elimination half-lives during intermittent hemodialysis (IHD) and continuous veno-venous hemodialysis/hemodiafiltration (CVVHD/HDF) and the relative impact of dialysate and blood flow rates on elimination. Data were obtained from 11 IHD and 13 CVVHD/HDF patients. Serum methanol and formate concentrations were measured by gas chromatography and an enzymatic method. The groups were relatively comparable, but the CVVHD/HDF group was significantly more acidotic (mean pH 6.9 vs. 7.1 IHD). The mean elimination half-life of methanol was 3.7 and formate 1.6 h with IHD, versus 8.1 and 3.6 h, respectively, with CVVHD/HDF (both significant). The 54% greater reduction in methanol and 56% reduction in formate elimination half-life during IHD resulted from the higher blood and dialysate flow rates. Increased blood and dialysate flow on the CVVHD/HDF also increased elimination significantly. Thus, IHD is superior to CVVHD/HDF for more rapid methanol and formate elimination, and if CVVHD/HDF is the only treatment available then elimination is greater with greater blood and dialysate flow rates. PMID:24621917

Use of a novel drainage flow servo-controlled CPB for mitral valve replacement in a Jehovah's Witness.

PubMed

Niimi, Yoshinari; Murata, Seiichiro; Mitou, Yumi; Ohno, Yusuke

2018-03-01

We developed a novel open cardiopulmonary bypass (CPB) system, a drainage flow servo-controlled CPB system (DS-CPB), in which rotational speed of the main roller pump is servo-controlled to generate the same amount of flow as the systemic venous drainage. It was designed to safely decrease the priming volume while maintaining a constant reservoir level, even during fluctuations of the drainage flow. We report a successful use of a novel DS-CPB system in an elderly Jehovah's Witness patient with dehydration who underwent mitral valve replacement.

In vitro evaluation of gaseous microemboli handling of cardiopulmonary bypass circuits with and without integrated arterial line filters.

PubMed

Liu, Saifei; Newland, Richard F; Tully, Phillip J; Tuble, Sigrid C; Baker, Robert A

2011-09-01

The delivery of gaseous microemboli (GME) by the cardiopulmonary bypass circuit should be minimized whenever possible. Innovations in components, such as the integration of arterial line filter (ALF) and ALFs with reduced priming volumes, have provided clinicians with circuit design options. However, before adopting these components clinically, their GME handling ability should be assessed. This study aims to compare the GME handling ability of different oxygenator/ALF combinations with our currently utilized combination. Five commercially available oxygenator/ALF combinations were evaluated in vitro: Terumo Capiox SX25RX and Dideco D734 (SX/D734),Terumo Capiox RX25R and AF125 (RX/AF125), Terumo FX25R (FX), Sorin Synthesis with 102 microm reservoir filter (SYN102), and Sorin Synthesis with 40 microm reservoir filter (SYN40). GME handling was studied by introducing air into the venous return at 100 mL/min for 60 seconds under two flow/ pressure combinations: 3.5 L/min, 150 mmHg and 5 L/min, 200 mmHg. Emboli were measured at three positions in the circuit using the Emboli Detection and Classification (EDAC) Quantifier and analyzed with the General Linear Model. All circuits significantly reduced GME. The SX/D734 and SYN40 circuits were most efficient in GME removal whilst the SYN102 handled embolic load (count and volume) least efficiently (p < .001). A greater number of emboli <70 microm were observed for the SYN102, FX and RX/AF125 circuits (p < .001). An increase in embolic load occurred with higher flow/pressure in all circuits (p < .001). The venous reservoir significantly influences embolic load delivered to the oxygenator (p < .001). The majority of introduced venous air was removed; however, significant variation existed in the ability of the different circuits to handle GME. Venous reservoir design influenced the overall GME handling ability. GME removal was less efficient at higher flow and pressure, and for smaller sized emboli. The clinical significance of reducing GME requires further investigation.

Comparison Between Retrograde and Antegrade Peripheral Venous Cannulation in Intensive Care Unit Patients: Assessment of Thrombus Formation.

PubMed

Abdelaal Ahmed Mahmoud, Ahmed; El-Shafei, Hassan Ismail; Yassin, Hany Mahmoud; Elramely, Mohamed Adly; Abdelhaq, Mohamed Mohamed; El Kady, Hany Wafiq; Awada, Wael Nabil Fahemy

2017-06-01

Antegrade cannulation of peripheral veins is the usual practice. Blood stasis between a catheter and the wall of the vein or at its tip in addition to catheter-induced phlebitis may initiate a thrombosis. The use of retrograde ventriculojugular shunts against the direction of the blood flow with resultant decrease in the incidence of venous thrombosis encouraged us to compare retrograde versus conventional antegrade peripheral venous cannulation. Monocentric, nonblinded, prospective observational cohort of 40 intensive care unit patients receiving 2 peripheral venous catheters in upper limbs, 1 inserted in the direction of blood flow (antegrade cannula) and the other inserted in an opposite direction to blood flow (retrograde cannula). Daily ultrasound assessment of the angle between the catheter and the vascular wall was done to detect onset and progression of thrombus formation. The study included 40 patients, aged 46.7 ± 10.132 years. The incidence of thrombus formation was 100% in both techniques. The onset time of thrombus formation between the catheter and the wall of a vein was significantly longer with the retrograde catheters than with the antegrade catheters with median time (interquartile range [range]) 6 days (5-6.75 [4-8]) with 95% confidence interval (CI), 5.58-6.42 vs 3 days (3-4 [2-5]) with 95% CI (2.76-3.24), respectively, with a P value <.001. The time needed by the recently detected thrombus to reach the catheter tip determined by ultrasound with or without catheter failure was significantly longer in the retrograde catheters than in the antegrade catheter with median time (interquartile range [range]) 9 days (8-9 [7-10]) with 95% CI, 8.76-9.24 vs 4 days (4-5 [3-6]) with 95% CI, 3.76-4.24, respectively, with a P value <.001. Retrograde cannulation did not decrease the incidence of thrombus formation, but significantly increased the onset time until thrombus formation and prolonged the time needed by the newly formed thrombus to reach the catheter tip compared with conventional antegrade cannulation.

A Predictive Framework to Elucidate Venous Stenosis: CFD & Shape Optimization.

PubMed

Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Hammes, Mary; Coe, Fredric

2017-07-01

The surgical creation of vascular accesses for renal failure patients provides an abnormally high flow rate conduit in the patient's upper arm vasculature that facilitates the hemodialysis treatment. These vascular accesses, however, are very often associated with complications that lead to access failure and thrombotic incidents, mainly due to excessive neointimal hyperplasia (NH) and subsequently stenosis. Development of a framework to monitor and predict the evolution of the venous system post access creation can greatly contribute to maintaining access patency. Computational fluid dynamics (CFD) has been exploited to inspect the non-homeostatic wall shear stress (WSS) distribution that is speculated to trigger NH in the patient cohort under investigation. Thereafter, CFD in liaison with a gradient-free shape optimization method has been employed to analyze the deformation modes of the venous system enduring non-physiological hemodynamics. It is observed that the optimally evolved shapes and their corresponding hemodynamics strive to restore the homeostatic state of the venous system to a normal, pre-surgery condition. It is concluded that a CFD-shape optimization coupling that seeks to regulate the WSS back to a well-defined physiological WSS target range can accurately predict the mode of patient-specific access failure.

A New Procedure for Wrapped-Negative Pressure Wound Therapy for Congestion After Arterialized Venous Flap Surgery

PubMed Central

Niimi, Yosuke; Mori, Satoko; Takeuchi, Masaki

2017-01-01

Negative pressure wound therapy (NPWT) is a method for treating wound. However, there are no case reports using NPWT for treating congestion after arterialized venous flap. Therefore, this study reported favorable outcomes after using a single-use NPWT system for managing congestion. A 39-year-old man had his index finger caught by a press machine. The finger had a soft tissue defect at the ventral part. An arterialized venous flap taken from the right forearm was transplanted. Perfusion of the flap was favorable, but on postoperative day 5, congestion and the edema of the flap were found. Then, NPWT was initiated. The congestion and edema in the flap were improved without complications such as flap necrosis and wound infection. At 4 months postoperatively, the morphology of the finger was favorable. In this study, NPWT was speculated to force the deeper blood vessels within the flap to dilate with inducing drainage and the simultaneous reduction in excess blood flow to the cortical layer, resulting in the improvement of congestion. Negative pressure wound therapy was used for treating congestion after the transplantation of arterialized venous flap, and the wound was favorably managed. PMID:29270041

Intraosseous haemangioma: semantic and medical confusion.

PubMed

Kadlub, N; Dainese, L; Coulomb-L'Hermine, A; Galmiche, L; Soupre, V; Lepointe, H Ducou; Vazquez, M-P; Picard, A

2015-06-01

The literature is rich in case reports of intraosseous haemangioma, although most of these are actually cases of venous or capillary malformations. To illustrate this confusion in terminology, we present three cases of slow-flow vascular malformations misnamed as intraosseous haemangioma. A retrospective study of children diagnosed with intraosseous haemangioma was conducted. Clinical and radiological data were evaluated. Histopathological examinations and immunohistochemical studies were redone by three independent pathologists to classify the lesions according to the International Society for the Study of Vascular Anomalies (ISSVA) and World Health Organization (WHO) classifications. Three children who had presented with jaw haemangiomas were identified. Computed tomography scan patterns were not specific. All tumours were GLUT-1-negative and D2-40-negative. The lesions were classified as central haemangiomas according to the WHO, and as slow-flow malformations according to the ISSVA. The classification of vascular anomalies is based on clinical, radiological, and histological differences between vascular tumours and malformations. Based on this classification, the evolution of the lesion can be predicted and adequate treatment applied. The binary ISSVA classification is widely accepted and should be applied for all vascular lesions. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Vascular anomalies and the growth of limbs: a review.

PubMed

Enjolras, Odile; Chapot, René; Merland, Jean Jacques

2004-11-01

Growth of the limb in a child can be impaired, with the coexistence of a vascular malformation. In these vascular bone syndromes, altered growth is manifest as overgrowth or hypotrophy. The vascular malformation is usually complex and gets progressively worse with time. The two types of vascular anomalies in limbs, fast-flow and slow-flow, can be associated with limb length discrepancies. The fast-flow vascular malformations together with arteriovenous fistulae are part of Parkes Weber syndrome, characterized by congenital red cutaneous staining, hypertrophy in girth and increasing of limb length, lymphedema, increasing skin alterations due to a distal vascular steal, and pain, all of which develop during childhood. Treatment is generally conservative. An affected lower extremity can be complicated by pelvic tilting and scoliosis because leg length discrepancy may reach 10 cm. To avoid such a course, stapling epiphysiodesis of the knee cartilages is often performed, but this orthopedic procedure may augment the worsening of the arterial venous malformation in the limb. Therefore, less aggressive orthopedic management is preferable. Slow-flow vascular anomalies associated with limb growth alteration include (1) a diffuse capillary malformation (port-wine stain) with congenital hypertrophy of the involved extremity which is non-progressive; (2) purely venous malformations invading skin, muscles and joints, with pain, functional impairment, a chronic localized intravascular coagulopathy requiring distinctive management, and usually a slight undergrowth of the affected extremity and progressing amyotrophy; (3) the triad of a port-wine stain, anomalous veins and overgrowth of the limb, often known as Klippel-Trenaunay syndrome, which requires orthopedic management to decide the optimal timing for epiphysiodesis (i.e. when leg length discrepancy is >2.5 cm). Varicose veins are sometimes surgically removed after ultrasonographic and Doppler evaluation has confirmed a normal deep venous system. Capillary malformations can be effectively treated with pulsed dye laser, but results are usually poor in distal extremities.

The Superior-Edge-of-the-Knee Incision Method in Lymphaticovenular Anastomosis for Lower Extremity Lymphedema.

PubMed

Seki, Yukio; Yamamoto, Takumi; Yoshimatsu, Hidehiko; Hayashi, Akitatsu; Kurazono, Arito; Mori, Masanori; Kato, Yoichi; Koshima, Isao

2015-11-01

Lymphatic vessel diameter and lymph flow are important for accurate anastomosis and effective lymph-to-venous flow in lymphaticovenular anastomosis. The authors developed a reliable method, the superioredge-of-the-knee incision method, for detecting and making the best use of high-flow lymphatic vessels in the distal medial thigh between the deep and superficial fascia, where movement of the knee, combined with compression between these fascial layers, theoretically results in upward propulsion of lymphatic fluid. Intraoperative detection of large lymphatic vessels and of venous reflux and postoperative lymphedematous volume reduction were compared between 15 patients in whom lymphaticovenular anastomoses with the superior-edge-of-the-knee incision method were undergone and 15 in whom conventional lymphaticovenular anastomoses were undergone. Lymphaticovenular anastomosis at the thigh yielded 30 anastomoses in the superior-edge-of-the-knee incision group and 32 anastomoses in the non-superior-edge-of-the-knee incision group. Large lymphatic vessels were more frequently found in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (60.0 percent versus 18.8 percent; p = 0.002). Venous reflux occurred less frequently in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (10.0 percent versus 65.6 percent; p < 0.001). Reduction of the lower extremity lymphedema index was significantly greater in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (24.427 ± 12.400 versus 0.032 ± 20.535; p < 0.001). The superior-edge-of-the-knee incision method facilitates detection and use of large, high-flow lymphatic vessels in the distal medial thigh, both of which are important for optimum therapeutic effects in patients with lower extremity lymphedema. Therapeutic, III.

Varicocele is the root cause of BPH: Destruction of the valves in the spermatic veins produces elevated pressure which diverts undiluted testosterone directly from the testes to the prostate.

PubMed

Goren, M; Gat, Y

2018-03-22

In varicocele, there is venous flow of free testosterone (FT) directly from the testes into the prostate. Intraprostatic FT accelerates prostate cell production and prolongs cell lifespan, leading to the development of BPH. We show that in a large group of patients presenting with BPH, bilateral varicocele is found in all patients. A total of 901 patients being treated for BPH were evaluated for varicocele. Three diagnostic methods were used as follows: physical examination, colour flow Doppler ultrasound and contact liquid crystal thermography. Bilateral varicocele was found in all 901 patients by at least one of three diagnostic methods. Of those subsequently treated by sclerotherapy, prostate volume was reduced in more than 80%, with prostate symptoms improved. A straightforward pathophysiologic connection exists between bilateral varicocele and BPH. The failure of the one-way valves in the internal spermatic veins leads to a cascade of phenomena that are unique to humans, a result of upright posture. The prostate is subjected to an anomalous venous supply of undiluted, bioactive free testosterone. FT, the obligate control hormone of prostate cells, reaches the prostate directly via the venous drainage system in high concentrations, accelerating the rate of cell production and lengthening cell lifespan, resulting in BPH. © 2018 Blackwell Verlag GmbH.

Measurement of Thrombus Flux Using Transesophageal Echocardiography

NASA Astrophysics Data System (ADS)

Yamaguchi, Tadashi; Hirai, Kazuki; Aoki, Masami; Miyagi, Jin; Suzuki, Masahiko; Moriya, Hideshige; Hachiya, Hiroyuki

2006-05-01

Deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE) are serious problem of total knee replacement (TKR). These diseases may be caused by a thrombus formed during the TKR operation. Therefore, understanding the flow volume of thrombus is important for curing and preventing PTE. In this paper, we tried to understanding the situation of the flow of thrombus by using transesophageal echocardiography movies. We applied the signal processing technique the FSET to extract the anomalous information from ultrasonic echo image. As a result of processing, the time change of the flow volume of thrombus was confirmed.

Preoperative ultrasound still valuable for radio-cephalic arteriovenous fistula creation?

PubMed

Pajek, Jernej; Malovrh, Marko

2017-03-06

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Evaluation of renal oxygen homeostasis in a preclinical animal model to elucidate difference in blood quality after transfusion.

PubMed

Baek, Jin Hyen; Yalamanoglu, Ayla; Moon, So-Eun; Gao, Yamei; Buehler, Paul W

2018-03-01

Red blood cell (RBC) oxygen (O 2 ) delivery may be impacted at the tissue, cellular, and molecular levels after storage duration, preservation strategies, and pathogen reduction. Collectively, the preclinical measurement of arterial and venous PO 2 , systemic blood flow, tissue hypoxia-inducible factors (HIFs), pimonidazole adduction, and erythropoietin (EPO) regulation can serve to elucidate differential RBC quality after storage and processing. Donor guinea pig blood was collected, leukoreduced, and stored at 4°C in AS-3 for 1 (fresh) or 14 (stored) days. RBC variables-2,3-diphosphoglycerate, adenosine triphosphate, hemoglobin, morphology, deformability, and in vivo recovery at 24 hours-were measured at each storage duration. Recipient guinea pigs were exchange transfused until 80% volume replacement was achieved. Arterial and venous blood gases, systemic blood flow, renal HIF-1α and HIF-2α, renal EPO mRNA, plasma EPO, and renal tissue pimonidazole adduction were measured after transfusion. RBC variables declined significantly with storage; however, hemolysis and in vivo recovery remained within the allowable limits for human blood storage. Posttransfusion arterial and venous PO 2 and systemic blood flow decreased, and renal HIFs, EPO mRNA, and pimonidazole adducts increased. Subsequently, EPO accumulated in plasma indicating decreased O 2 availability in the kidneys. Conversely, all variables remained at basal levels in the fresh blood group. The evaluation of renal O 2 homeostasis after transfusion represents an effective approach to defining RBC quality between predicate and novel processing. Methods are adapted from standardized techniques and ideal for preclinical evaluation. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Quantitative evaluation of hand cranking a roller pump in a crisis management drill.

PubMed

Tomizawa, Yasuko; Tokumine, Asako; Ninomiya, Shinji; Momose, Naoki; Matayoshi, Toru

2008-01-01

The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person's performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur.

Effect of herbal medicine daikenchuto on oral and enteral caloric intake after liver transplantation: A multicenter, randomized controlled trial.

PubMed

Kaido, Toshimi; Shinoda, Masahiro; Inomata, Yukihiro; Yagi, Takahito; Akamatsu, Nobuhisa; Takada, Yasutsugu; Ohdan, Hideki; Shimamura, Tsuyoshi; Ogura, Yasuhiro; Eguchi, Susumu; Eguchi, Hidetoshi; Ogata, Satoshi; Yoshizumi, Tomoharu; Ikegami, Toshihiko; Yamamoto, Michio; Morita, Satoshi; Uemoto, Shinji

2018-03-20

Postoperative early oral or enteral intake is a crucial element of the Enhanced Recovery After Surgery (ERAS) protocol. However, normal food intake or enteral feeding cannot be started early in the presence of coexisting bowel dysfunction in patients undergoing liver transplantation (LT). The aim of this multicenter, randomized, double-blinded, placebo-controlled trial was to determine the enhancement effects of the Japanese herbal medicine Daikenchuto (DKT) on oral/enteral caloric intake in patients undergoing LT. A total of 112 adult patients undergoing LT at 14 Japanese centers were enrolled. The patients were randomly assigned to receive either DKT or placebo from postoperative day (POD) 1 to 14. The primary endpoints were total oral/enteral caloric intake, abdominal distension, and pain on POD 7. The secondary endpoints included sequential changes in total oral/enteral caloric intake after LT, and portal venous flow volume and velocity in the graft. A total of 104 patients (DKT, n = 55; placebo, n = 49) were included in the analyses. There were no significant differences between the two groups in terms of primary endpoints. However, postoperative total oral/enteral caloric intake was significantly accelerated in the DKT group compared with the placebo group (P = 0.023). Moreover, portal venous flow volume (POD 10, 14) and velocity (POD 14) were significantly higher in the DKT group than in the placebo group (P = 0.047, P = 0.025, P = 0.014, respectively). Postoperative administration of DKT may enhance total oral/enteral caloric intake and portal venous flow volume and velocity after LT and favorably contribute to the performance of the ERAS protocol. Copyright © 2018 Elsevier Inc. All rights reserved.

The timing of umbilical cord clamping at birth: physiological considerations.

PubMed

Hooper, Stuart B; Binder-Heschl, Corinna; Polglase, Graeme R; Gill, Andrew W; Kluckow, Martin; Wallace, Euan M; Blank, Douglas; Te Pas, Arjan B

2016-01-01

While it is now recognized that umbilical cord clamping (UCC) at birth is not necessarily an innocuous act, there is still much confusion concerning the potential benefits and harms of this common procedure. It is most commonly assumed that delaying UCC will automatically result in a time-dependent net placental-to-infant blood transfusion, irrespective of the infant's physiological state. Whether or not this occurs, will likely depend on the infant's physiological state and not on the amount of time that has elapsed between birth and umbilical cord clamping (UCC). However, we believe that this is an overly simplistic view of what can occur during delayed UCC and ignores the benefits associated with maintaining the infant's venous return and cardiac output during transition. Recent experimental evidence and observations in humans have provided compelling evidence to demonstrate that time is not a major factor influencing placental-to-infant blood transfusion after birth. Indeed, there are many factors that influence blood flow in the umbilical vessels after birth, which depending on the dominating factors could potentially result in infant-to-placental blood transfusion. The most dominant factors that influence umbilical artery and venous blood flows after birth are lung aeration, spontaneous inspirations, crying and uterine contractions. It is still not entirely clear whether gravity differentially alters umbilical artery and venous flows, although the available data suggests that its influence, if present, is minimal. While there is much support for delaying UCC at birth, much of the debate has focused on a time-based approach, which we believe is misguided. While a time-based approach is much easier and convenient for the caregiver, ignoring the infant's physiology during delayed UCC can potentially be counter-productive for the infant.

Shear stress and flow dynamics of the femoral vein among obese patients who qualify for bariatric surgery.

PubMed

Wiewiora, Maciej; Piecuch, Jerzy; Glűck, Marek; Slowinska-Lozynska, Ludmila; Sosada, Krystyn

2013-01-01

The aim of this study was to evaluate the effects of obesity on wall shear stress and its relationship to erythrocyte aggregation. We studied 35 morbidly obese patients who were qualified for bariatric surgery. The control group consisted of 20 non-obese people. Blood rheological measurements were performed using the Laser-assisted Optical Rotational Cell Analyzer (Mechatronics, the Netherlands) and a cone-plate viscometer (Brookfield DV-II). The venous flow dynamics were assessed using a duplex ultrasound. The shear rate was estimated from the measured blood flow velocity and the diameter of the femoral vein. Venous wall shear stress was calculated from the whole blood viscosity and the shear rate. The shear rate (P < 0.005) and the venous wall shear stress (P < 0.05) were significantly lower in obese patients compared with the controls. The aggregation index (P < 0.001), syllectogram amplitude - AMP (P < 0.05) and Tslow (P < 0.001) were significantly higher in the obese patients; the aggregation half-time (P < 0.001) and Tfast (P < 0.001) were decreased compared with the control group. Multivariate regression analyses found waist circumference (β -0.31, P < 0.05), thigh circumference (β 0.33, P < 0.05) and Tslow (β -0.47, P < 0.005) to be variables that independently influenced the shear rate. Nevertheless, the AMP (β 0.34, P < 0.05) and Tslow (β -0.47, P < 0.01) were independent predictors that influenced the wall shear stress. This study indicates that there is a relationship between wall shear stress in the femoral vein and the rheological impairment of the RBC among obese patients, but further studies are necessary to confirm this suggestion.

An investigation of cerebral oxygen utilization, blood flow and cognition in healthy aging.

PubMed

Catchlove, Sarah J; Macpherson, Helen; Hughes, Matthew E; Chen, Yufen; Parrish, Todd B; Pipingas, Andrew

2018-01-01

Understanding how vascular and metabolic factors impact on cognitive function is essential to develop efficient therapies to prevent and treat cognitive losses in older age. Cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and venous oxygenation (Yv) comprise key physiologic processes that maintain optimum functioning of neural activity. Changes to these parameters across the lifespan may precede neurodegeneration and contribute to age-related cognitive decline. This study examined differences in blood flow and metabolism between 31 healthy younger (<50 years) and 29 healthy older (>50 years) adults; and investigated whether these parameters contribute to cognitive performance. Participants underwent a cognitive assessment and MRI scan. Grey matter CMRO2 was calculated from measures of CBF (phase contrast MRI), arterial and venous oxygenation (TRUST MRI) to assess group differences in physiological function and the contribution of these parameters to cognition. Performance on memory (p<0.001) and attention tasks (p<0.001) and total CBF were reduced (p<0.05), and Yv trended toward a decrease (p = .06) in the older group, while grey matter CBF and CMRO2 did not differ between the age groups. Attention was negatively associated with CBF when adjusted (p<0.05) in the older adults, but not in the younger group. There was no such relationship with memory. Neither cognitive measure was associated with oxygen metabolism or venous oxygenation in either age group. Findings indicated an age-related imbalance between oxygen delivery, consumption and demand, evidenced by a decreased supply of oxygen with unchanged metabolism resulting in increased oxygen extraction. CBF predicted attention when the age-effect was controlled, suggesting a task- specific CBF- cognition relationship.

Whole blood flow cytometry measurements of in vivo platelet activation in critically-Ill patients are influenced by variability in blood sampling techniques.

PubMed

Rondina, Matthew T; Grissom, Colin K; Men, Shaohua; Harris, Estelle S; Schwertz, Hansjorg; Zimmerman, Guy A; Weyrich, Andrew S

2012-06-01

Flow cytometry is often used to measure in vivo platelet activation in critically-ill patients. Variability in blood sampling techniques, which may confound these measurements, remains poorly characterized. Platelet activation was measured by flow cytometry performed on arterial and venous blood from 116 critically-ill patients. We determined how variability in vascular sampling site, processing times, and platelet counts influenced levels of platelet-monocyte aggregates (PMA), PAC-1 binding (for glycoprotein (GP) IIbIIIa), and P-selectin (P-SEL) expression. Levels of PMA, but not PAC-1 binding or P-SEL expression, were significantly affected by variability in vascular sampling site. Average PMA levels were approximately 60% higher in whole blood drawn from an arterial vessel compared to venous blood (16.2±1.8% vs. 10.7±1.2%, p<0.05). Levels of PMA in both arterial and venous blood increased significantly during ex vivo processing delays (1.7% increase for every 10 minute delay, p<0.05). In contrast, PAC-1 binding and P-SEL expression were unaffected by processing delays. Levels of PMA, but not PAC-1 binding or P-SEL expression, were correlated with platelet count quartiles (9.4±1.6% for the lowest quartile versus 15.4±1.6% for the highest quartile, p<0.05). In critically-ill patients, variability in vascular sampling site, processing times, and platelet counts influence levels of PMA, but not PAC-1 binding or P-SEL expression. These data demonstrate the need for rigorous adherence to blood sampling protocols, particularly when levels of PMA, which are most sensitive to variations in blood collection, are measured for detection of in vivo platelet activation. Copyright © 2011 Elsevier Ltd. All rights reserved.

CT perfusion imaging of the liver and the spleen in patients with cirrhosis: Is there a correlation between perfusion and portal venous hypertension?

PubMed

Talakić, Emina; Schaffellner, Silvia; Kniepeiss, Daniela; Mueller, Helmut; Stauber, Rudolf; Quehenberger, Franz; Schoellnast, Helmut

2017-10-01

To correlate hepatic and splenic CT perfusion parameters with hepatic venous pressure gradient (HVPG) measurements in patients with cirrhosis. Twenty-one patients with cirrhosis (males, 17; females, 4; mean ± SD age, 57 ± 7 years) underwent hepatic and splenic perfusion CT on a 320-detector row volume scanner as well as invasive measurement of HVPG. Different CT perfusion algorithms (maximum slope analysis and Patlak plot) were used to measure hepatic arterial flow (HAF), portal venous flow (PVF), hepatic perfusion index (HPI), splenic arterial flow (SAF), splenic blood volume (SBV) and splenic clearance (SCL). Hepatic and splenic perfusion parameters were correlated with HVPG, and sensitivity and specificity for detection of severe portal hypertension (≥12 mmHg) were calculated. The Spearman correlation coefficient was -0.53 (p < 0.05) between SAF and HVPG, and -0.68 (p < 0.01) between HVPG and SCL. Using a cut-off value of 125 ml/min/100 ml for SCL, sensitivity for detection of a HVPG of ≥12 mmHg was 94%, and specificity 100%. There was no significant correlation between hepatic perfusion parameters and HVPG. CT perfusion in patients with cirrhosis showed a strong correlation between SCL and HVPG and may be used for detection of severe portal hypertension. • SAF and SCL are statistically significantly correlated with HVPG • SCL showed stronger correlation with HVPG than SAF • 125 ml/min/100 ml SCL-cut-off yielded 94 % sensitivity, 100 % specificity for severe PH • HAF, PVF and HPI showed no statistically significant correlation with HVPG.

Experimental Cerebral Malaria Pathogenesis—Hemodynamics at the Blood Brain Barrier

PubMed Central

Nacer, Adéla; Movila, Alexandru; Sohet, Fabien; Girgis, Natasha M.; Gundra, Uma Mahesh; Loke, P'ng; Daneman, Richard; Frevert, Ute

2014-01-01

Cerebral malaria claims the lives of over 600,000 African children every year. To better understand the pathogenesis of this devastating disease, we compared the cellular dynamics in the cortical microvasculature between two infection models, Plasmodium berghei ANKA (PbA) infected CBA/CaJ mice, which develop experimental cerebral malaria (ECM), and P. yoelii 17XL (PyXL) infected mice, which succumb to malarial hyperparasitemia without neurological impairment. Using a combination of intravital imaging and flow cytometry, we show that significantly more CD8+ T cells, neutrophils, and macrophages are recruited to postcapillary venules during ECM compared to hyperparasitemia. ECM correlated with ICAM-1 upregulation on macrophages, while vascular endothelia upregulated ICAM-1 during ECM and hyperparasitemia. The arrest of large numbers of leukocytes in postcapillary and larger venules caused microrheological alterations that significantly restricted the venous blood flow. Treatment with FTY720, which inhibits vascular leakage, neurological signs, and death from ECM, prevented the recruitment of a subpopulation of CD45hi CD8+ T cells, ICAM-1+ macrophages, and neutrophils to postcapillary venules. FTY720 had no effect on the ECM-associated expression of the pattern recognition receptor CD14 in postcapillary venules suggesting that endothelial activation is insufficient to cause vascular pathology. Expression of the endothelial tight junction proteins claudin-5, occludin, and ZO-1 in the cerebral cortex and cerebellum of PbA-infected mice with ECM was unaltered compared to FTY720-treated PbA-infected mice or PyXL-infected mice with hyperparasitemia. Thus, blood brain barrier opening does not involve endothelial injury and is likely reversible, consistent with the rapid recovery of many patients with CM. We conclude that the ECM-associated recruitment of large numbers of activated leukocytes, in particular CD8+ T cells and ICAM+ macrophages, causes a severe restriction in the venous blood efflux from the brain, which exacerbates the vasogenic edema and increases the intracranial pressure. Thus, death from ECM could potentially occur as a consequence of intracranial hypertension. PMID:25474413

[Solar phase effect on elasticity of the brachial artery and blood flow in humans].

PubMed

Mel'nikov, V N; Komliagina, T G; Rechkina, S Iu; Krivoshchekov, S G

2010-01-01

Single and double examinations of normal males and females in the course of 11-year solar cycle with the use of oscillovasometry and occlusive plethysmography established a direct correlation between the effective diastolic radius of the brachial artery and solar activity characteristics on the day of examination, i.e. number of solar spots and intensity of radiation with the 10.7 cm wavelength. Other blood flow parameters demonstrated opposite correlations with the factors in males and females. As solar activity increased, females displayed linear decrements of arterial elasticity and regional peripheral resistance and growth of the volumetric blood flow velocity equally at rest and at the peak of post-occlusion reactive hyperemia. In males, the correlations had the reversed sign. Besides, males were noted to reduce venous reserve and venous outflow from antebrachial muscles proportionally to the increase of Wolf number. It is inferred that elevated solar activity may be responsible for impairment of the feeling of well-being of people with reduced cardiovascular reserve, particularly in space tight or at high altitudes in the absence of or under weak protection of the geomagnetic field and ozone layer.

Systems analysis of thrombus formation

PubMed Central

Diamond, Scott L.

2016-01-01

The systems analysis of thrombosis seeks to quantitatively predict blood function in a given vascular wall and hemodynamic context. Relevant to both venous and arterial thrombosis, a Blood Systems Biology approach should provide metrics for rate and molecular mechanisms of clot growth, thrombotic risk, pharmacological response, and utility of new therapeutic targets. As a rapidly created multicellular aggregate with a polymerized fibrin matrix, blood clots result from hundreds of unique reactions within and around platelets propagating in space and time under hemodynamic conditions. Coronary artery thrombosis is dominated by atherosclerotic plaque rupture, complex pulsatile flows through stenotic regions producing high wall shear stresses, and plaque-derived tissue factor driving thrombin production. In contrast, venous thrombosis is dominated by stasis or depressed flows, endothelial inflammation, white blood cell-derived tissue factor, and ample red blood cell incorporation. By imaging vessels, patient-specific assessment using computational fluid dynamics provides an estimate of local hemodynamics and fractional flow reserve. High dimensional ex vivo phenotyping of platelet and coagulation can now power multiscale computer simulations at the subcellular to cellular to whole vessel scale of heart attacks or strokes. Additionally, an integrated systems biology approach can rank safety and efficacy metrics of various pharmacological interventions or clinical trial designs. PMID:27126646

Independent effects of heart-head distance and caudal blood pooling on blood pressure regulation in aquatic and terrestrial snakes.

PubMed

Seymour, Roger S; Arndt, Joachim O

2004-03-01

Changes in orientation in a gravitational field markedly alter the patterns of blood pressure and flow in animals, especially tall or long ones such as giraffes or snakes. Vertical orientation tends to reduce blood flow and pressure in the head for two major reasons. First, the increased vertical blood column above the heart creates a gravitational hydrostatic pressure against which the heart must work. Second, expansion of dependent vessels in the lower extremities causes blood pooling and reduces return of venous blood to the heart, thereby lowering flow and pressure. For most animals, it is difficult to separate these two effects, but snakes offer the possibility of bending the animal in the region of the heart and manipulating the two ends of the body independently. We studied baroregulatory responses in terrestrial pythons (Liasis fuscus) and aquatic file snakes (Acrochordus arafurae) by tilting only the front or rear parts and then the whole animal. Changes in head blood pressure during partial tilts added up to the change during full tilt. The vertical distance to the head had twice as much influence on head blood pressure than did blood pooling in the pythons and four times as much in file snakes. This accounts for the cephalad location of the heart in terrestrial species compared with aquatic ones.

Oscillatory patterns in sympathetic neural discharge and cardiovascular variables during orthostatic stimulus

NASA Technical Reports Server (NTRS)

Furlan, R.; Porta, A.; Costa, F.; Tank, J.; Baker, L.; Schiavi, R.; Robertson, D.; Malliani, A.; Mosqueda-Garcia, R.

2000-01-01

BACKGROUND: We tested the hypothesis that a common oscillatory pattern might characterize the rhythmic discharge of muscle sympathetic nerve activity (MSNA) and the spontaneous variability of heart rate and systolic arterial pressure (SAP) during a physiological increase of sympathetic activity induced by the head-up tilt maneuver. METHODS AND RESULTS: Ten healthy subjects underwent continuous recordings of ECG, intra-arterial pressure, respiratory activity, central venous pressure, and MSNA, both in the recumbent position and during 75 degrees head-up tilt. Venous samplings for catecholamine assessment were obtained at rest and during the fifth minute of tilt. Spectrum and cross-spectrum analyses of R-R interval, SAP, and MSNA variabilities and of respiratory activity provided the low (LF, 0.1 Hz) and high frequency (HF, 0.27 Hz) rhythmic components of each signal and assessed their linear relationships. Compared with the recumbent position, tilt reduced central venous pressure, but blood pressure was unchanged. Heart rate, MSNA, and plasma epinephrine and norepinephrine levels increased, suggesting a marked enhancement of overall sympathetic activity. During tilt, LF(MSNA) increased compared with the level in the supine position; this mirrored similar changes observed in the LF components of R-R interval and SAP variabilities. The increase of LF(MSNA) was proportional to the amount of the sympathetic discharge. The coupling between LF components of MSNA and R-R interval and SAP variabilities was enhanced during tilt compared with rest. CONCLUSIONS: During the sympathetic activation induced by tilt, a similar oscillatory pattern based on an increased LF rhythmicity characterized the spontaneous variability of neural sympathetic discharge, R-R interval, and arterial pressure.

Surgical Anatomy of the Left Lateral Segment as Applied to Living-Donor and Split-Liver Transplantation

PubMed Central

Reichert, Paulo R.; Renz, John F.; D’Albuquerque, Luiz A. C.; Rosenthal, Philip; Lim, Robert C.; Roberts, John P.; Ascher, Nancy L.; Emond, Jean C.

2000-01-01

Objective To evaluate intrahepatic vascular and biliary anatomy of the left lateral segment (LLS) as applied to living-donor and split-liver transplantation. Summary Background Data Living-donor and split-liver transplantation are innovative surgical techniques that have expanded the donor pool. Fundamental to the application of these techniques is an understanding of intrahepatic vascular and biliary anatomy. Methods Pathologic data obtained from cadaveric liver corrosion casts and liver dissections were clinically correlated with the anatomical findings obtained during split-liver, living-donor, and reduced-liver transplants. Results The anatomical relation of the left bile duct system with respect to the left portal venous system was constant, with the left bile duct superior to the extrahepatic transverse portion of the left portal vein. Four specific patterns of left biliary anatomy and three patterns of left hepatic venous drainage were identified and described. Conclusions Although highly variable, the biliary and hepatic venous anatomy of the LLS can be broadly categorized into distinct patterns. The identification of the LLS duct origin lateral to the umbilical fissure in segment 4 in 50% of cast specimens is significant in the performance of split-liver and living-donor transplantation, because dissection of the graft pedicle at the level of the round ligament will result in separate ducts from segments 2 and 3 in most patients, with the further possibility of an anterior segment 4 duct. A connective tissue bile duct plate, which can be clinically identified, is described to guide dissection of the segment 2 and 3 biliary radicles. PMID:11066137

Management of traumatic popliteal vein injuries.

PubMed

Ekim, Hasan; Basel, Halil; Odabasi, Dolunay

2012-09-01

The aim of this study was to evaluate different repair methods of popliteal vein injuries, and to assess the relationship between early patency and surgical outcome. Thirty patients with popliteal vein injuries underwent surgical repair procedure at our hospital from March 2000 to April 2010. Patients who were haemodynamically unstable and those with massive bleeding from limb wounds were taken directly to the operating room. Stable patients underwent preoperative colour-flow duplex ultrasonography (CFDU). Our study group consisted of 26 males and 4 females, ranging in age from 17 to 60 years with a mean age of 25.3 ± 5.9 years. The mechanism of trauma was penetrating in 27 patients and blunt in the remaining 3 patients. Treatment included primary venous repair in 11 cases, end-to-end anastomosis in 8, interposition vein graft in 10, and interposition polytetrafluoroethylene (PTFE) graft in 1. There were 26 patients with associated arterial injury, of which 4 cases had primary repair, 9 had end-to-end anastomosis, 11 had saphenous vein graft interposition, and 2 had PTFE graft interposition. Associated bone fracture was seen in 6 patients. There were no deaths. One patient required a below-knee amputation. Postoperative CFDU revealed thrombosed venous repair in 7 cases without any sequelae. Popliteal venous injuries can be repaired with minimal downside and a good early patency rate. Additionally, transient venous patency allows for establishment of venous and lymphatic collateralisation. Alternatively, venous ligation should be considered only in unstable patients who refuse blood transfusion (Jehovah's witnesses). In these victims, adjuvant management may be required such as the use of fasciotomy and anticoagulation treatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Prevalence of Extracranial Venous Narrowing on Magnetic Resonance Venography Is Similar in People With Multiple Sclerosis, Their Siblings, and Unrelated Healthy Controls: A Blinded, Case-Control Study.

PubMed

Martin, Nancy; Traboulsee, Anthony L; Machan, Lindsay; Klass, Darren; Ellchuk, Tasha; Zhao, Yinshan; Knox, Katherine B; Kopriva, David; Lala, Shantilal; Nickel, Darren; Otani, Robert; Perera, Warren R; Rauscher, Alexander; Sadovnick, A Dessa; Szkup, Peter; Li, David K

2017-05-01

The study sought to assess and compare the prevalence of narrowing of the major extracranial veins in subjects with multiple sclerosis and controls, and to assess the sensitivity and specificity of magnetic resonance venography (MRV) for describing extracranial venous narrowing as it applies to the chronic cerebrospinal venous insufficiency theory, using catheter venography (CV) as the gold standard. The jugular and azygos veins were assessed with time-of-flight MRV in this assessor-blinded, case-control study of subjects with multiple sclerosis, their unaffected siblings, and unrelated controls. The veins were evaluated by diameter and area, and compared with CV. Collateral vessels were also analyzed for maximal diameter, as a potential indicator of compensatory flow. A high prevalence of extracranial venous narrowing was demonstrated in all study groups, collectively up to 84% by diameter criteria and 90% by area, with no significant difference between the groups when assessed independently (P = .34 and .63, respectively). There was high interobserver variability in the reporting of vessel narrowing (kappa = 0.32), and poor vessel per vessel correlation between narrowing on MRV and CV (kappa = 0.064). Collateral neck veins demonstrated no convincing difference in maximum size or correlation with jugular narrowing. There is a high prevalence of narrowing of the major extracranial veins on MRV in all 3 study groups, with no significant difference between them. These findings do not support the chronic cerebrospinal venous insufficiency theory. Although MRV has shown a high sensitivity for identifying venous narrowing, time-of-flight imaging demonstrates poor interobserver agreement and poor specificity when compared with the gold standard CV. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

Low-frequency high-definition power Doppler in visualizing and defining fetal pulmonary venous connections.

PubMed

Liu, Lin; He, Yihua; Li, Zhian; Gu, Xiaoyan; Zhang, Ye; Zhang, Lianzhong

2014-07-01

The use of low-frequency high-definition power Doppler in assessing and defining pulmonary venous connections was investigated. Study A included 260 fetuses at gestational ages ranging from 18 to 36 weeks. Pulmonary veins were assessed by performing two-dimensional B-mode imaging, color Doppler flow imaging (CDFI), and low-frequency high-definition power Doppler. A score of 1 was assigned if one pulmonary vein was visualized, 2 if two pulmonary veins were visualized, 3 if three pulmonary veins were visualized, and 4 if four pulmonary veins were visualized. The detection rate between Exam-1 and Exam-2 (intra-observer variability) and between Exam-1 and Exam-3 (inter-observer variability) was compared. In study B, five cases with abnormal pulmonary venous connection were diagnosed and compared to their anatomical examination. In study A, there was a significant difference between CDFI and low-frequency high-definition power Doppler for the four pulmonary veins observed (P < 0.05). The detection rate of each pulmonary vein when employing low-frequency high-definition power Doppler was higher than that when employing two-dimensional B-mode imaging or CDFI. There was no significant difference between the intra- and inter-observer variabilities using low-frequency high-definition power Doppler display of pulmonary veins (P > 0.05). The coefficient correlation between Exam-1 and Exam-2 was 0.844, and the coefficient correlation between Exam-1 and Exam-3 was 0.821. In study B, one case of total anomalous pulmonary venous return and four cases of partial anomalous pulmonary venous return were diagnosed by low-frequency high-definition power Doppler and confirmed by autopsy. The assessment of pulmonary venous connections by low-frequency high-definition power Doppler is advantageous. Pulmonary venous anatomy can and should be monitored during fetal heart examination.

Isolated Deep Venous Thrombosis: Implications for 2-Point Compression Ultrasonography of the Lower Extremity.

PubMed

Adhikari, Srikar; Zeger, Wes; Thom, Christopher; Fields, J Matthew

2015-09-01

Two-point compression ultrasonography focuses on the evaluation of common femoral and popliteal veins for complete compressibility. The presence of isolated thrombi in proximal veins other than the common femoral and popliteal veins should prompt modification of 2-point compression technique. The objective of this study is to determine the prevalence and distribution of deep venous thrombi isolated to lower-extremity veins other than the common femoral and popliteal veins in emergency department (ED) patients with clinically suspected deep venous thrombosis. This was a retrospective study of all adult ED patients who received a lower-extremity venous duplex ultrasonographic examination for evaluation of deep venous thrombosis during a 6-year period. The ultrasonographic protocol included B-mode, color-flow, and spectral Doppler scanning of the common femoral, femoral, deep femoral, popliteal, and calf veins. Deep venous thrombosis was detected in 362 of 2,451 patients (14.7%; 95% confidence interval [CI] 13.3% to 16.1%). Thrombus confined to the common femoral vein alone was found in 5 of 362 cases (1.4%; 95% CI 0.2% to 2.6%). Isolated femoral vein thrombus was identified in 20 of 362 patients (5.5%; 95% CI 3.2% to 7.9%). Isolated deep femoral vein thrombus was found in 3 of 362 cases (0.8%; 95% CI -0.1% to 1.8%). Thrombus in the popliteal vein alone was identified in 53 of 362 cases (14.6%; 95% CI 11% to 18.2%). In our study, 6.3% of ED patients with suspected deep venous thrombosis had isolated thrombi in proximal veins other than common femoral and popliteal veins. Our study results support the addition of femoral and deep femoral vein evaluation to standard compression ultrasonography of the common femoral and popliteal vein, assuming that this does not have a deleterious effect on specificity. Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

Quantifying the effects of external shear loads on arterial and venous blood flow: implications for pressure ulcer development.

PubMed

Manorama, Abinand; Meyer, Ronald; Wiseman, Robert; Bush, Tamara Reid

2013-06-01

Forces applied to the skin cause a decrease in regional blood flow. This decrease in blood flow can cause tissue necrosis and lead to the formation of deep, penetrating wounds called pressure ulcers. These wounds are detrimental to individuals with compromised health, such as the elderly and spinal-cord injured. Although surface pressure is known to be a primary risk factor for developing a pressure ulcer, a seated individual rarely experiences pressure alone but rather combined loading which includes pressure as well as shear force on the skin. However, little research has been conducted to quantify the effects of shear forces on blood flow. Fifteen men were tested in a magnetic resonance imaging scanner under no load, a normal load, and a combination of normal and shear loads. Changes in arterial and venous blood flow in the forearm were measured using magnetic resonance angiography phase-contrast imaging. The blood flow in the anterior interosseous artery and basilic vein of the forearm decreased with the application of normal loads, and decreased further with the addition of shear loads. Marginal to significant differences at a 90% confidence level (P=0.08, 0.10) were observed, and medium to high effect sizes (0.3 to 0.5) were obtained. Based on these results, shear force is an important factor to consider in relation to pressure ulcer propagation and prevention, and hence, future prevention approaches should also focus on mitigating shear loads. Copyright © 2013 Elsevier Ltd. All rights reserved.

One dimensional blood flow in a planetocentric orbit

NASA Astrophysics Data System (ADS)

Haranas, Ioannis; Gkigkitzis, Ioannis

2012-05-01

All life on earth is accustomed to the presence of gravity. When gravity is altered, biological processes can go awry. It is of great importance to ensure safety during a spaceflight. Long term exposure to microgravity can trigger detrimental physiological responses in the human body. Fluid redistribution coupled with fluid loss is one of the effects. In particular, in microgravity blood volume is shifted towards the thorax and head. Sympathetic nervous system-induced vasoconstriction is needed to maintain arterial pressure, while venoconstriction limits venous pooling of blood prevents further reductions in venous return of blood to the heart. In this paper, we modify an existing one dimensional blood flow model with the inclusion of the hydrostatic pressure gradient that further depends on the gravitational field modified by the oblateness and rotation of the Earth. We find that the velocity of the blood flow VB is inversely proportional to the blood specific volume d, also proportional to the oblateness harmonic coefficient J2, the angular velocity of the Earth ωE, and finally proportional to an arbitrary constant c. For c = -0.39073 and ξH = -0.5 mmHg, all orbits result to less blood flow velocities than that calculated on the surface of the Earth. From all considered orbits, elliptical polar orbit of eccentricity e = 0.2 exhibit the largest flow velocity VB = 1.031 m/s, followed by the orbits of inclination i = 45°and 0°. The Earth's oblateness and its rotation contribute a 0.7% difference to the blood flow velocity.

Intrahepatic portosystemic venous shunt: diagnosis by color Doppler imaging.

PubMed

Kudo, M; Tomita, S; Tochio, H; Minowa, K; Todo, A

1993-05-01

Intrahepatic portosystemic venous shunt is a rare clinical entity; only 33 such cases have been reported. It may be congenital, or secondary to portal hypertension. Five patients with this disorder are presented, each of whom was diagnosed by color Doppler imaging, including waveform spectral analysis. One patient with clinical evidence of cirrhosis and portal hypertension had episodes of hepatic encephalopathy and elevated blood levels of ammonia. This patient had a large tubular shunt between the posterior branch of the portal vein and the inferior vena cava. Shunts of this type are considered to be collateral pathways which develop in the hepatic parenchyma as a result of portal hypertension. The other four patients had no evidence of liver disease, and all four evidenced an aneurysmal portohepatic venous shunt within the liver parenchyma. Shunts of this type are considered congenital. The diagnosis of intrahepatic portosystemic venous shunts was established by color Doppler imaging, which demonstrated a direct communication of color flow signals between the portal vein and hepatic vein, in addition to the characterization of the Doppler spectrum at each sampling point from a continuous waveform signal (portal vein) to a turbulent signal (aneurysmal cavity), and finally, to a biphasic waveform signal (hepatic vein). As demonstrated by the five patients, color Doppler imaging is useful in the diagnosis of an intrahepatic portosystemic hepatic venous shunt, and the measurement of shunt ratio may be useful in the follow-up and determining the therapeutic option.

Development and testing of an artificial arterial and venous pulse oximeter.

PubMed

Cloete, G; Fourie, P R; Scheffer, C

2013-01-01

The monitoring of patients healthcare is of a prime importance to ensure their efficient and effective treatment. Monitoring blood oxygen saturation is a field which has grown significantly in recent times and more specifically in tissues affected by diseases or conditions that may negatively affect the function of the tissue. This study involved the development and testing of a highly sensitive non-invasive blood oxygen saturation monitoring device. A device that can be used to continuously monitor the condition of tissue affected by diseases which affect the blood flow through the tissue, and the oxygen usage in tissue. The device's system was designed to specifically monitor occluded tissue which has low oxygen saturations and low perfusion. Although with limitted validation the system was unable to accurately measure the venous oxygenation specifically, but it was able to measure the mixed oxygen saturation. With further research it would be possible to validate the system for measuring both the arterial and venous oxygen saturations.

Distended Bladder Presenting with Altered Mental Status and Venous Obstruction

PubMed Central

Washco, Vaughan; Engel, Lee; Smith, David L.; McCarron, Ross

2015-01-01

Background New onset or acute worsening of bilateral lower extremity swelling is commonly caused by venous congestion from decompensated heart failure, pulmonary disease, liver dysfunction, or kidney insufficiency. A thromboembolic event, lymphatic obstruction, or even external compression of venous flow can also be the culprit. Case Report We report the case of an 83-year-old male with a history of myelodysplastic syndrome that progressed to acute myeloid leukemia, bipolar disorder, and benign prostatic hypertrophy. He presented with altered mental status and new onset lower extremity edema caused by acute bladder outflow obstruction. Computed tomography of the abdomen and pelvis showed the patient's distended bladder compressing bilateral external iliac veins. Conclusion Insertion of a Foley catheter resulted in several liters of urine output and marked improvement in his lower extremity edema and mental status a few hours later. Our extensive workup failed to reveal a cause of the patient's acute change in mental status, and we attributed it to a concept known as cystocerebral syndrome. PMID:25829883

Intralesional sclerotherapy for subcutaneous venous malformations in children.

PubMed

Uehara, Shuichiro; Osuga, Keigo; Yoneda, Akihiro; Oue, Takaharu; Yamanaka, Hiroaki; Fukuzawa, Masahiro

2009-08-01

Venous malformations (VMs) involve multiple anatomical spaces and encase critical neuromuscular structures, making surgical treatment difficult. Recently sclerotherapy has been suggested as the primary treatment for VMs instead of surgical intervention. This report represents eight cases of children with VMs treated with direct percutaneous injections of sclerosing agents, such as ethanol, polidocanol or ethanolamine oleate. All eight patients had large lesions (>3 cm) located on the head, foot, neck and face. Sclerotherapy was performed in an angiographic suite under general anesthesia. Prior to sclerotherapy, percutaneous phlebography was performed in order to visualize the dynamic situation inside the lesion and the draining flow into the adjacent venous vascular system. A 2-15 ml of sclerosing agent was injected into VM lesions under fluoroscopy. An evaluation by MRI examination showed that 6 out of 8 patients had remission, and alleviation of their symptoms without major complications, furthermore one of the lesions apparently disappeared. Intralesional sclerotherapy provides a simple, safe and effective treatment for VMs in the subcutaneous lesions in children.

Restoration of hemodynamics in apnea struggle phase in association with involuntary breathing movements.

PubMed

Palada, Ivan; Bakovic, Darija; Valic, Zoran; Obad, Ante; Ivancev, Vladimir; Eterovic, Davor; Shoemaker, J Kevin; Dujic, Zeljko

2008-04-30

Involuntary breathing movements (IBM) that occur in the struggle phase of maximal apneas produce waves of negative intrathoracic pressure. This could augment the venous return, increasing thereby the cardiac output and gas exchange, and release the fresh blood from venous pools of spleen and liver. To test these hypotheses we used photoplethysmography and ultrasound for assessment of hemodynamics and spleen size before, during and after maximal dry apneas at large lung volume in 7 trained divers. During the easy-going phase cardiac output was reduced about 40%, due to reduction in stroke volume and in presence of reduced inferior vena cava venous return, while the spleen contracted for about 60 ml. Towards the end of the struggle phase, in presence of intense IBM, the spleen volume further decreased for about 70 ml, while cardiac output and caval flow almost renormalized. In conclusion, IBM coincide with splenic volume reduction and restoration of hemodynamics, likely facilitating the use of the last oxygen reserves before apnea cessation.

Inadvertent venous air embolism during cesarean section: collapsible intravenous fluid bags without self-sealing outlet have risks. Case report.

PubMed

Bakan, Mefkur; Topuz, Ufuk; Esen, Asim; Basaranoglu, Gokcen; Ozturk, Erdogan

2013-01-01

The anesthesiologist must be aware of the causes, diagnosis and treatment of venous air embolism and adopt the practice patterns to prevent its occurrence. Although venous air embolism is a known complication of cesarean section, we describe an unusual inattention that causes iatrogenic near fatal venous air embolism during a cesarean section under spinal anesthesia. One of the reasons for using self-collapsible intravenous (IV) infusion bags instead of conventional glass or plastic bottles is to take precaution against air embolism. We also demonstrated the risk of air embolism for two kinds of plastic collapsible intravenous fluid bags: polyvinyl chloride (PVC) and polypropylene-based. Fluid bags without self-sealing outlets pose a risk for air embolism if the closed system is broken down, while the flexibility of the bag limits the amount of air entry. PVC-based bags, which have more flexibility, have significantly less risk of air entry when IV administration set is disconnected from the outlet. Using a pressure bag for rapid infusion can be dangerous without checking and emptying all air from the IV bag. 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Inadvertent venous air embolism during cesarean section: Collapsible intravenous fluid bags without self-sealing outlet have risks. Case report.

PubMed

Bakan, Mefkur; Topuz, Ufuk; Esen, Asim; Basaranoglu, Gokcen; Ozturk, Erdogan

2013-01-01

The anesthesiologist must be aware of the causes, diagnosis and treatment of venous air embolism and adopt the practice patterns to prevent its occurrence. Although venous air embolism is a known complication of cesarean section, we describe an unusual inattention that causes iatrogenic near fatal venous air embolism during a cesarean section under spinal anesthesia. One of the reasons for using self-collapsible intravenous (IV) infusion bags instead of conventional glass or plastic bottles is to take precaution against air embolism. We also demonstrated the risk of air embolism for two kinds of plastic collapsible intravenous fluid bags: polyvinyl chloride (PVC) and polypropylene-based. Fluid bags without self-sealing outlets pose a risk for air embolism if the closed system is broken down, while the flexibility of the bag limits the amount of air entry. PVC-based bags, which have more flexibility, have significantly less risk of air entry when IV administration set is disconnected from the outlet. Using a pressure bag for rapid infusion can be dangerous without checking and emptying all air from the IV bag. Copyright © 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Predictability of the future development of aggressive behavior of cranial dural arteriovenous fistulas based on decision tree analysis.

PubMed

Satomi, Junichiro; Ghaibeh, A Ammar; Moriguchi, Hiroki; Nagahiro, Shinji

2015-07-01

The severity of clinical signs and symptoms of cranial dural arteriovenous fistulas (DAVFs) are well correlated with their pattern of venous drainage. Although the presence of cortical venous drainage can be considered a potential predictor of aggressive DAVF behaviors, such as intracranial hemorrhage or progressive neurological deficits due to venous congestion, accurate statistical analyses are currently not available. Using a decision tree data mining method, the authors aimed at clarifying the predictability of the future development of aggressive behaviors of DAVF and at identifying the main causative factors. Of 266 DAVF patients, 89 were eligible for analysis. Under observational management, 51 patients presented with intracranial hemorrhage/infarction during the follow-up period. The authors created a decision tree able to assess the risk for the development of aggressive DAVF behavior. Evaluated by 10-fold cross-validation, the decision tree's accuracy, sensitivity, and specificity were 85.28%, 88.33%, and 80.83%, respectively. The tree shows that the main factor in symptomatic patients was the presence of cortical venous drainage. In its absence, the lesion location determined the risk of a DAVF developing aggressive behavior. Decision tree analysis accurately predicts the future development of aggressive DAVF behavior.

Multimodal noninvasive and invasive imaging of extracranial venous abnormalities indicative of CCSVI: Results of the PREMiSe pilot study

PubMed Central

2013-01-01

Background There is no established noninvasive or invasive diagnostic imaging modality at present that can serve as a ‘gold standard’ or “benchmark” for the detection of the venous anomalies, indicative of chronic cerebrospinal venous insufficiency (CCSVI). We investigated the sensitivity and specificity of 2 invasive vs. 2 noninvasive imaging techniques for the detection of extracranial venous anomalies in the internal jugular veins (IJVs) and azygos vein/vertebral veins (VVs) in patients with multiple sclerosis (MS). Methods The data for this multimodal imaging comparison pilot study was collected in phase 2 of the “Prospective Randomized Endovascular therapy in Multiple Sclerosis” (PREMiSe) study using standardized imaging techniques. Thirty MS subjects were screened initially with Doppler sonography (DS), out of which 10 did not fulfill noninvasive screening procedure requirements on DS that consisted of ≥2 venous hemodynamic extracranial criteria. Accordingly, 20 MS patients with relapsing MS were enrolled into the multimodal diagnostic imaging study. For magnetic resonance venography (MRV), IJVs abnormal findings were considered absent or pinpoint flow, whereas abnormal VVs flow was classified as absent. Abnormalities of the VVs were determined only using non-invasive testing. Catheter venography (CV) was considered abnormal when ≥50% lumen restriction was detected, while intravascular ultrasound (IVUS) was considered abnormal when ≥50% restriction of the lumen or intra-luminal defects or reduced pulsatility was found. Non-invasive and invasive imaging modality comparisons between left, right and total IJVs and between the VVs and azygos vein were performed. Because there is no reliable way of non-invasively assessing the azygos vein, the VVs abnormalities detected by the non-invasive testing were compared to the azygos abnormalities detected by the invasive testing. All image modalities were analyzed in a blinded manner by more than one viewer, upon which consensus was reached. The sensitivity and specificity were calculated using contingency tables denoting the presence or absence of vein-specific abnormality findings between all imaging modalities used individually as the benchmark. Results The sensitivity of CV + IVUS was 68.4% for the right and 90% for the left IJV and 85.7% for the azygos vein/VVs, compared to venous anomalies detected on DS. Compared to the venous anomalies detected on MRV, the sensitivity of CV + IVUS was 71.4% in right and 100% in left IJVs and 100% in the azygos vein/VVs; however, the specificity was 38.5%, 38.9% and 11.8%, respectively. The sensitivity between the two invasive imaging techniques, used as benchmarks, ranged from 72.7% for the right IJV to 90% for the azygos vein but the IVUS showed a higher rate of venous anomalies than the CV. There was excellent correspondence between identifying collateral veins on MRV and CV. Conclusions Noninvasive DS screening for the detection of venous anomalies indicative of CCSVI may be a reliable approach for identifying patients eligible for further multimodal invasive imaging testing of the IJVs. However, the noninvasive screening methods were inadequate to depict the total amount of azygos vein/VVs anomalies identified with invasive testing. This pilot study, with limited sample size, shows that both a non-invasive and invasive multimodal imaging diagnostic approach should be recommended to depict a range of extracranial venous anomalies indicative of CCSVI. However, lack of invasive testing on the study subjects whose results were negative on the DS screening and of healthy controls, limits further generalizibility of our findings. In addition, the findings from the 2 invasive techniques confirmed the existence of severe extracranial venous anomalies that significantly impaired normal blood outflow from the brain in this group of MS patients. PMID:24139135

Control system for an artificial heart

NASA Technical Reports Server (NTRS)

Gebben, V. D.; Webb, J. A., Jr.

1970-01-01

Inexpensive industrial pneumatic components are combined to produce control system to drive sac-type heart-assistance blood pump with controlled pulsatile pressure that makes pump rate of flow sensitive to venous /atrial/ pressure, while stroke is centered about set operating point and pump is synchronized with natural heart.

Intramucosal–arterial PCO2 gap fails to reflect intestinal dysoxia in hypoxic hypoxia

PubMed Central

Dubin, Arnaldo; Murias, Gastón; Estenssoro, Elisa; Canales, Héctor; Badie, Julio; Pozo, Mario; Sottile, Juan P; Barán, Marcelo; Pálizas, Fernando; Laporte, Mercedes

2002-01-01

Introduction An elevation in intramucosal–arterial PCO2 gradient (ΔPCO2) could be determined either by tissue hypoxia or by reduced blood flow. Our hypothesis was that in hypoxic hypoxia with preserved blood flow, ΔPCO2 should not be altered. Methods In 17 anesthetized and mechanically ventilated sheep, oxygen delivery was reduced by decreasing flow (ischemic hypoxia, IH) or arterial oxygen saturation (hypoxic hypoxia, HH), or no intervention was made (sham). In the IH group (n = 6), blood flow was lowered by stepwise hemorrhage; in the HH group (n = 6), hydrochloric acid was instilled intratracheally. We measured cardiac output, superior mesenteric blood flow, gases, hemoglobin, and oxygen saturations in arterial blood, mixed venous blood, and mesenteric venous blood, and ileal intramucosal PCO2 by tonometry. Systemic and intestinal oxygen transport and consumption were calculated, as was ΔPCO2. After basal measurements, measurements were repeated at 30, 60, and 90 minutes. Results Both progressive bleeding and hydrochloric acid aspiration provoked critical reductions in systemic and intestinal oxygen delivery and consumption. No changes occurred in the sham group. ΔPCO2 increased in the IH group (12 ± 10 [mean ± SD] versus 40 ± 13 mmHg; P < 0.001), but remained unchanged in HH and in the sham group (13 ± 6 versus 10 ± 13 mmHg and 8 ± 5 versus 9 ± 6 mmHg; not significant). Discussion In this experimental model of hypoxic hypoxia with preserved blood flow, ΔPCO2 was not modified during dependence of oxygen uptake on oxygen transport. These results suggest that ΔPCO2 might be determined primarily by blood flow. PMID:12493073

Deep vein thrombus formation induced by flow reduction in mice is determined by venous side branches.

PubMed

Brandt, Moritz; Schönfelder, Tanja; Schwenk, Melanie; Becker, Christian; Jäckel, Sven; Reinhardt, Christoph; Stark, Konstantin; Massberg, Steffen; Münzel, Thomas; von Brühl, Marie-Luise; Wenzel, Philip

2014-01-01

Interaction between vascular wall abnormalities, inflammatory leukocytes, platelets, coagulation factors and hemorheology in the pathogenesis of deep vein thrombosis (DVT) is incompletely understood, requiring well defined animal models of human disease. We subjected male C57BL/6 mice to ligation of the inferior vena cava (IVC) as a flow reduction model to induce DVT. Thrombus size and weight were analyzed macroscopically and sonographically by B-mode, pulse wave (pw) Doppler and power Doppler imaging (PDI) using high frequency ultrasound. Thrombus size varied substantially between individual procedures and mice, irrespective of the flow reduction achieved by the ligature. Interestingly, PDI accurately predicted thrombus size in a very robust fashion (r2 = 0.9734, p < 0.0001). Distance of the insertion of side branches from the ligature significantly determines thrombus weight (r2 = 0.5597, p < 0.0001) and length (r2 = 0.5441, p < 0.0001) in the IVC, regardless of the flow measured by pw-Doppler with distances <1.5 mm drastically impairing thrombus formation. Occlusion of side branches prior to ligation of IVC did not increase thrombus size, probably due to patent side branches inaccessible to surgery. Venous side branches influence thrombus size in experimental DVT and might therefore prevent thrombus formation. This renders vessel anatomy and hemorheology important determinants in mouse models of DVT, which should be controlled for.

Successful transcatheter occlusion of an anomalous pulmonary vein with dual drainage to the left atrium.

PubMed

Wilson, W; Horlick, E; Benson, L

2015-06-01

We describe a case of a scimitar syndrome "variant" where dual drainage existed from the right upper and middle pulmonary veins to the inferior vena cava and left atrium. Device closure of the anomalous vein at the level of the connection to the IVC was successful in achieving diversion of pulmonary venous flow to the left atrium. Vigilance during work-up of anomalous pulmonary venous drainage (whether isolated or associated with other cardiac defects that may be amenable to device closure) is important to define the presence of dual connections to the left atrium, in which case a less-invasive transcatheter approach may be feasible. © 2015 Wiley Periodicals, Inc.

Postoperative complications after lower extremity arterial bypass increase the risk of new deep venous thrombosis.

PubMed

Aziz, Faisal; Lehman, Erik; Blebea, John; Lurie, Fedor

2017-01-01

Background Deep venous thrombosis after any surgical operations is considered a preventable complication. Lower extremity bypass surgery is a commonly performed operation to improve blood flow to lower extremities in patients with severe peripheral arterial disease. Despite advances in endovascular surgery, lower extremity arterial bypass remains the gold standard treatment for severe, symptomatic peripheral arterial disease. The purpose of this study is to identify the clinical risk factors associated with development of deep venous thrombosis after lower extremity bypass surgery. Methods The American College of Surgeons' NSQIP database was utilized and all lower extremity bypass procedures performed in 2013 were examined. Patient and procedural characteristics were evaluated. Univariate and multivariate logistic regression analysis was used to determine independent risk factors for the development of postoperative deep venous thrombosis. Results A total of 2646 patients (65% males and 35% females) underwent lower extremity open revascularization during the year 2013. The following factors were found to be significantly associated with postoperative deep venous thrombosis: transfusion >4 units of packed red blood cells (odds ratio (OR) = 5.21, confidence interval (CI) = 1.29-22.81, p = 0.03), postoperative urinary tract infection (OR = 12.59, CI = 4.12-38.48, p < 0.01), length of hospital stay >28 days (OR = 9.30, CI = 2.79-30.92, p < 0.01), bleeding (OR = 2.93, CI = 1.27-6.73, p = 0.01), deep wound infection (OR = 3.21, CI = 1.37-7.56, p < 0.01), and unplanned reoperation (OR = 4.57, CI = 2.03-10.26, p < 0.01). Of these, multivariable analysis identified the factors independently associated with development of deep venous thrombosis after lower extremity bypass surgery to be unplanned reoperation (OR = 3.57, CI = 1.54-8.30, p < 0.01), reintubation (OR = 8.93, CI = 2.66-29.97, p < 0.01), and urinary tract infection (OR = 7.64, CI = 2.27-25.73, p < 0.01). Presence of all three factors was associated with a 54% incidence of deep venous thrombosis. Conclusions Development of deep venous thrombosis after lower extremity bypass is a serious but infrequent complication. Patients who require unplanned return to the operating room, reintubation, or develop a postoperative urinary tract are at high risk for developing postoperative deep venous thrombosis. Increased monitoring of these patients and ensuring adequate deep venous thrombosis prophylaxis for such patients is suggested.

Endothelial cells (ECs) for vascular tissue engineering: venous ECs are less thrombogenic than arterial ECs.

PubMed

Geenen, I L A; Molin, D G M; van den Akker, N M S; Jeukens, F; Spronk, H M; Schurink, G W H; Post, M J

2015-05-01

Primary endothelial cells (ECs) are the preferred cellular source for luminal seeding of tissue-engineered (TE) vascular grafts. Research into the potential of ECs for vascular TE has focused particularly on venous rather than arterial ECs. In this study we evaluated the functional characteristics of arterial and venous ECs, relevant for vascular TE. Porcine ECs were isolated from femoral artery (PFAECs) and vein (PFVECs). The proliferation rate was comparable for both EC sources, whereas migration, determined through a wound-healing assay, was less profound for PFVECs. EC adhesion was lower for PFVECs on collagen I, measured after 10 min of arterial shear stress. Gene expression was analysed by qRT-PCR for ECs cultured under static conditions and after exposure to arterial shear stress and revealed differences in gene expression, with lower expression of EphrinB2 and VCAM-1 and higher levels of vWF and COUP-TFII in PFVECs than in PFAECs. PFVECs exhibited diminished platelet adhesion under flow and cell-based thrombin generation was delayed for PFVECs, indicating diminished tissue factor (TF) activity. After stimulation, prostacyclin secretion, but not nitric oxide (NO), was lower in PFVECs. Our data support the use of venous ECs for TE because of their beneficial antithrombogenic profile. Copyright © 2012 John Wiley & Sons, Ltd.

Postural effects on the noninvasive baselines of ventricular performance

NASA Technical Reports Server (NTRS)

Lance, V. Q.; Spodick, D. H.

1977-01-01

The effects of posture on time-based noninvasive measurements were determined utilizing the sequence supine-sitting-standing in a formal protocol in which observer biases were eliminated by blinding the measurement and calculation phases. Compared to the supine posture, the sitting and standing postures produced significant increases in heart rate, isovolumic contraction time, pre-ejection period and pre-ejection period/left-ventricular ejection time and significant decreases in ejection time and ejection time index. The response patterns are consistent with the hemodynamic correlates cited in the literature which show increased adrenergic activity and decreased venous return in the sitting and standing postures, the effect on venous return being dominant.

Nursing Theory, Terminology, and Big Data: Data-Driven Discovery of Novel Patterns in Archival Randomized Clinical Trial Data.

PubMed

Monsen, Karen A; Kelechi, Teresa J; McRae, Marion E; Mathiason, Michelle A; Martin, Karen S

The growth and diversification of nursing theory, nursing terminology, and nursing data enable a convergence of theory- and data-driven discovery in the era of big data research. Existing datasets can be viewed through theoretical and terminology perspectives using visualization techniques in order to reveal new patterns and generate hypotheses. The Omaha System is a standardized terminology and metamodel that makes explicit the theoretical perspective of the nursing discipline and enables terminology-theory testing research. The purpose of this paper is to illustrate the approach by exploring a large research dataset consisting of 95 variables (demographics, temperature measures, anthropometrics, and standardized instruments measuring quality of life and self-efficacy) from a theory-based perspective using the Omaha System. Aims were to (a) examine the Omaha System dataset to understand the sample at baseline relative to Omaha System problem terms and outcome measures, (b) examine relationships within the normalized Omaha System dataset at baseline in predicting adherence, and (c) examine relationships within the normalized Omaha System dataset at baseline in predicting incident venous ulcer. Variables from a randomized clinical trial of a cryotherapy intervention for the prevention of venous ulcers were mapped onto Omaha System terms and measures to derive a theoretical framework for the terminology-theory testing study. The original dataset was recoded using the mapping to create an Omaha System dataset, which was then examined using visualization to generate hypotheses. The hypotheses were tested using standard inferential statistics. Logistic regression was used to predict adherence and incident venous ulcer. Findings revealed novel patterns in the psychosocial characteristics of the sample that were discovered to be drivers of both adherence (Mental health Behavior: OR = 1.28, 95% CI [1.02, 1.60]; AUC = .56) and incident venous ulcer (Mental health Behavior: OR = 0.65, 95% CI [0.45, 0.93]; Neuro-musculo-skeletal function Status: OR = 0.69, 95% CI [0.47, 1.00]; male: OR = 3.08, 95% CI [1.15, 8.24]; not married: OR = 2.70, 95% CI [1.00, 7.26]; AUC = .76). The Omaha System was employed as ontology, nursing theory, and terminology to bridge data and theory and may be considered a data-driven theorizing methodology. Novel findings suggest a relationship between psychosocial factors and incident venous ulcer outcomes. There is potential to employ this method in further research, which is needed to generate and test hypotheses from other datasets to extend scientific investigations from existing data.

Facts about Total Anomalous Pulmonary Venous Return or TAPVR

MedlinePlus

... and the right atrium. The goal of the surgical repair of TAPVR is to restore normal blood flow through the heart. To repair this defect, doctors usually connect the pulmonary veins to the left atrium, close off any abnormal connections between blood vessels, and close the atrial septal ...

Sinus pericranii: diagnosis and management in 21 pediatric patients.

PubMed

Pavanello, Marco; Melloni, Ilaria; Antichi, Eleonora; Severino, Mariasavina; Ravegnani, Marcello; Piatelli, Gianluca; Cama, Armando; Rossi, Andrea; Gandolfo, Carlo

2015-01-01

Sinus pericranii (SP) is a rare venous anomaly abnormally connecting the intracranial dural sinuses with the epicranial veins. In the present study the authors aimed to clarify this clinicoradiological entity, define the role of angiography in its preoperative assessment, and suggest a diagnostic-therapeutic flow chart for management purposes. The authors retrospectively reviewed the clinical charts and neuroimages of 21 patients with SP. All patients underwent brain MRI, MR venography, and craniocerebral CT. Diagnostic digital subtraction angiography was performed in 19 of 21 patients, and the SPs were categorized as dominant (draining the majority of the intracranial venous outflow) or accessory (draining only a minority of the intracranial venous outflow). SP was median or paramedian in 20 patients and lateral in 1 patient. There were 5 dominant and 14 accessory SPs. The dominant SPs were not treated. Among the patients with accessory SP, 4 were not treated, 2 underwent surgical ligature, and 8 were treated endovascularly (with either transvenous or percutaneous embolization). No complications were observed, and symptoms disappeared after treatment in all cases. Accepted guidelines or recommendations concerning the management, diagnosis, and treatment of SP are still lacking. The authors define here a diagnostic-therapeutic flow chart, in which angiography plays a crucial role in the classification of SP and choice of the optimal treatment. Only accessory SP is amenable to treatment, whereas dominant SP must be preserved. The endovascular approach is becoming increasingly relevant and has proven to be safe and effective.

Use of an intravascular fluorescent continuous glucose sensor in subjects with type 1 diabetes mellitus.

PubMed

Romey, Matthew; Jovanovič, Lois; Bevier, Wendy; Markova, Kateryna; Strasma, Paul; Zisser, Howard

2012-11-01

Stress hyperglycemia in the critically ill is associated with increased morbidity and mortality. Continuous glucose monitoring offers a solution to the difficulties of dosing intravenous insulin properly to maintain glycemic control. The purpose of this study was to evaluate an intravascular continuous glucose monitoring (IV-CGM) system with a sensing element based on the concept of quenched fluorescence. A second-generation intravascular continuous glucose sensor was evaluated in 13 volunteer subjects with type 1 diabetes mellitus. There were 21 study sessions of up to 24 h in duration. Sensors were inserted into peripheral veins of the upper extremity, up to two sensors per subject per study session. Sensor output was compared with temporally correlated reference measurements obtained from venous samples on a laboratory glucose analyzer. Data were obtained from 23 sensors in 13 study sessions with 942 paired reference values. Fourteen out of 23 sensors (60.9%) had a mean absolute relative difference ≤ 10%. Eighty-nine percent of paired points were in the clinically accurate A zone of the Clarke error grid and met ISO 15197 performance criteria. Adequate venous blood flow was identified as a necessary condition for accuracy when local sensor readings are compared with venous blood glucose. The IV-CGM system was capable of achieving a high level of glucose measurement accuracy. However, superficial peripheral veins may not provide adequate blood flow for reliable indwelling blood glucose monitoring. © 2012 Diabetes Technology Society.

Use of an Intravascular Fluorescent Continuous Glucose Sensor in Subjects with Type 1 Diabetes Mellitus

PubMed Central

Romey, Matthew; Jovanovič, Lois; Bevier, Wendy; Markova, Kateryna; Strasma, Paul; Zisser, Howard

2012-01-01

Background Stress hyperglycemia in the critically ill is associated with increased morbidity and mortality. Continuous glucose monitoring offers a solution to the difficulties of dosing intravenous insulin properly to maintain glycemic control. The purpose of this study was to evaluate an intravascular continuous glucose monitoring (IV-CGM) system with a sensing element based on the concept of quenched fluorescence. Method A second-generation intravascular continuous glucose sensor was evaluated in 13 volunteer subjects with type 1 diabetes mellitus. There were 21 study sessions of up to 24 h in duration. Sensors were inserted into peripheral veins of the upper extremity, up to two sensors per subject per study session. Sensor output was compared with temporally correlated reference measurements obtained from venous samples on a laboratory glucose analyzer. Results Data were obtained from 23 sensors in 13 study sessions with 942 paired reference values. Fourteen out of 23 sensors (60.9%) had a mean absolute relative difference ≤ 10%. Eighty-nine percent of paired points were in the clinically accurate A zone of the Clarke error grid and met ISO 15197 performance criteria. Adequate venous blood flow was identified as a necessary condition for accuracy when local sensor readings are compared with venous blood glucose. Conclusions The IV-CGM system was capable of achieving a high level of glucose measurement accuracy. However, superficial peripheral veins may not provide adequate blood flow for reliable indwelling blood glucose monitoring. PMID:23294770

Cerebral hemodynamic changes of mild traumatic brain injury at the acute stage.

PubMed

Doshi, Hardik; Wiseman, Natalie; Liu, Jun; Wang, Wentao; Welch, Robert D; O'Neil, Brian J; Zuk, Conor; Wang, Xiao; Mika, Valerie; Szaflarski, Jerzy P; Haacke, E Mark; Kou, Zhifeng

2015-01-01

Mild traumatic brain injury (mTBI) is a significant public health care burden in the United States. However, we lack a detailed understanding of the pathophysiology following mTBI and its relation to symptoms and recovery. With advanced magnetic resonance imaging (MRI), we can investigate brain perfusion and oxygenation in regions known to be implicated in symptoms, including cortical gray matter and subcortical structures. In this study, we assessed 14 mTBI patients and 18 controls with susceptibility weighted imaging and mapping (SWIM) for blood oxygenation quantification. In addition to SWIM, 7 patients and 12 controls had cerebral perfusion measured with arterial spin labeling (ASL). We found increases in regional cerebral blood flow (CBF) in the left striatum, and in frontal and occipital lobes in patients as compared to controls (p = 0.01, 0.03, 0.03 respectively). We also found decreases in venous susceptibility, indicating increases in venous oxygenation, in the left thalamostriate vein and right basal vein of Rosenthal (p = 0.04 in both). mTBI patients had significantly lower delayed recall scores on the standardized assessment of concussion, but neither susceptibility nor CBF measures were found to correlate with symptoms as assessed by neuropsychological testing. The increased CBF combined with increased venous oxygenation suggests an increase in cerebral blood flow that exceeds the oxygen demand of the tissue, in contrast to the regional hypoxia seen in more severe TBI. This may represent a neuroprotective response following mTBI, which warrants further investigation.

Effect of body position and ventilation on umbilical artery and venous blood flows during delayed umbilical cord clamping in preterm lambs.

PubMed

Hooper, Stuart B; Crossley, Kelly J; Zahra, Valerie A; van Vonderen, Jeroen; Moxham, Alison; Gill, Andrew W; Kluckow, Martin; Te Pas, Arjan B; Wallace, Euan M; Polglase, Graeme R

2017-07-01

While delayed umbilical cord clamping (UCC) is thought to facilitate placental to infant blood transfusion, the physiological factors regulating flow in the umbilical arteries and veins during delayed UCC is unknown. We investigated the effects of gravity, by changing fetal height relative to the placenta, and ventilation on umbilical blood flows and the cardiovascular transition during delayed UCC at birth. Catheters and flow probes were implanted into preterm lambs (128 days) prior to delivery to measure pulmonary, carotid, umbilical artery (UaBF) and umbilical venous (UvBF) blood flows. Lambs were placed either 10 cm below or 10 cm above the ewe. Ventilation commenced 2-3 min before UCC and continued for 30 min after UCC. Gravity reduced umbilical and cerebral flows when lambs were placed below the midline, but the reduction in UaBF and UvBF was similar. Ventilation during delayed UCC reduced UvBF and UaBF by similar amounts, irrespective of the lamb's position, such that flows into and out of the placenta remained balanced. The effects of ventilation on umbilical flows were much greater than the effects of gravity, but no net placental to lamb blood transfusion could be detected under any condition. Cardiovascular parameters, cerebral oxygen kinetics and final blood volumes were similar in both groups 5 min after UCC. Gravity caused small transient effects on umbilical and cerebral flow, but given changes were similar in umbilical arteries and veins, no net placental transfusion was detected. Ventilation during delayed UCC has a markedly greater influence on cardiovascular function in the newborn. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Ultrasonography of Skin Changes in Legs with Chronic Venous Disease.

PubMed

Caggiati, A

2016-10-01

In daily practice, ultrasonography (US) is used only to designate the location and pattern of venous lesions. Skin US is not performed between routine venous investigations. Skin morphology is evaluated by the same probes used for routine Duplex evaluation of superficial veins. US findings from evident skin lesions are comparatively evaluated with those from the surrounding apparently normal skin and from the contralateral leg. Inflammation and dermal edema can be found in the apparently normal skin of C2 legs. Swollen legs show thickening of the subcutaneous layer as a result of diffuse soaking or anechoic cavities, with or without dermal edema. Chronic hypodermitis is characterized by inflammatory edema in initial phases, and by liposclerosis in advanced cases. Recrudescence of inflammation provokes focal rarefactions of the subcutaneous layer, possibly related to ulcer opening. In legs with venous disorders, sonography refines clinical evaluation of the skin and may reveal changes not highlighted by inspection. Some of these changes could require further investigation because they have not yet been explained or described. Skin sonography should improve knowledge of the natural history of skin changes, as well as contribute to a better grading of venous diseases severity In particular, US evidence of cutaneous and subcutaneous changes in C2 legs should be considered to stratify the treatment in C2 legs, by identifying those in which varicose veins are not simply a cosmetic problem. Copyright © 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Performance increase in venous drainage for mini-invasive heart surgery: superiority of self-expanding cannulas.

PubMed

Belkoniene, Mhedi; Abdel-Sayed, Saad; Favre, Julien; von Segesser, Ludwig-Karl

2014-01-01

Originally, the Smartcanula principle (collapsed insertion and expansion in situ) was developed for venous drainage by gravity. However, in minimally invasive surgery, augmentation with either constrained force vortex pumps or vacuum is often used. The current study was set up to assess whether smaller diameters of self-expanding venous cannulas are sufficient in conjunction with venous drainage augmentation resulting in smaller access orifices. To evaluate cannulas intended for cardiopulmonary bypass, an in vitro circuit was set up with silicone tubing between the test cannula encased in a lower reservoir, the centrifugal pump, and after an upper reservoir. Afterload was set arbitrarily at 60 mm Hg using a centrifugal pump. The pressure value was measured using Millar pressure transducers. Flow rate (Q) was measured using an ultrasonic flow meter calibrated with volume tank and timer. Revolutions per minute of the centrifugal pump were calibrated with a stroboscope. Data display and data recording were controlled using a Lab View application. Self-expanding (24F Smartcanula) and control (25F Biomedicus) cannulas were used. Sixty measurements were recorded. At pump speed of 1500, 1570, 2000, 2500, and 3000 rpm, the Q values were 3.6, 5.2, 6.6, 9.3, and 11.8 L/min for the 24F self-expanding cannula and 3, 4.3, 5.4, 7.5, and 9.3 L/min for the control cannula. The pressure values were 3.6, -5.4, -15.9, -45.3, and 80.6 mm Hg. Biomedicus 25F showed Q values from 16% to 19% less as compared with 24F Smartcanula. The pressure values were 6, 7, 4, 2, and 2 times more as compared with 24F Smartcanula. Our experimental evaluation demonstrated the superior performance of the Smartcanula with its self-expanding design in comparison with the reference commercially available standard cannulas. The Smartcanula with its small diameter is particularly welcome for minimally invasive surgery.

The Physiologic Effects of Pneumoperitoneum in the Morbidly Obese

PubMed Central

Nguyen, Ninh T.; Wolfe, Bruce M.

2005-01-01

Objective: To review the physiologic effects of carbon dioxide (CO2) pneumoperitoneum in the morbidly obese. Summary Background Data: The number of laparoscopic bariatric operations performed in the United States has increased dramatically over the past several years. Laparoscopic bariatric surgery requires abdominal insufflation with CO2 and an increase in the intraabdominal pressure up to 15 mm Hg. Many studies have demonstrated the adverse consequences of pneumoperitoneum; however, few studies have examined the physiologic effects of pneumoperitoneum in the morbidly obese. Methods: A MEDLINE search from 1994 to 2003 was performed using the key words morbid obesity, laparoscopy, bariatric surgery, pneumoperitoneum, and gastric bypass. The authors reviewed papers evaluating the physiologic effects of pneumoperitoneum in morbidly obese subjects undergoing laparoscopy. The topics examined included alteration in acid-base balance, hemodynamics, femoral venous flow, and hepatic, renal, and cardiorespiratory function. Results: Physiologically, morbidly obese patients have a higher intraabdominal pressure at 2 to 3 times that of nonobese patients. The adverse consequences of pneumoperitoneum in morbidly obese patients are similar to those observed in nonobese patients. Laparoscopy in the obese can lead to systemic absorption of CO2 and increased requirements for CO2 elimination. The increased intraabdominal pressure enhances venous stasis, reduces intraoperative portal venous blood flow, decreases intraoperative urinary output, lowers respiratory compliance, increases airway pressure, and impairs cardiac function. Intraoperative management to minimize the adverse changes include appropriate ventilatory adjustments to avoid hypercapnia and acidosis, the use of sequential compression devices to minimizes venous stasis, and optimize intravascular volume to minimize the effects of increased intraabdominal pressure on renal and cardiac function. Conclusions: Morbidly obese patients undergoing laparoscopic bariatric surgery are at risk for intraoperative complications relating to the use of CO2 pneumoperitoneum. Surgeons performing laparoscopic bariatric surgery should understand the physiologic effects of CO2 pneumoperitoneum in the morbidly obese and make appropriate intraoperative adjustments to minimize the adverse changes. PMID:15650630

The time-course of red blood cell intracellular pH recovery following short-circuiting in relation to venous transit times in rainbow trout, Oncorhynchus mykiss.

PubMed

Harter, Till Sebastian; May, Alexandra G; Federspiel, William J; Supuran, Claudiu T; Brauner, Colin J

2018-04-11

Accumulating evidence is highlighting the importance of a system of enhanced hemoglobin-oxygen (Hb-O 2 ) unloading for cardiovascular O 2 transport in teleosts. Adrenergically stimulated sodium-proton-exchangers (β-NHE) create H + gradients across the red blood cell (RBC) membrane that are short-circuited in the presence of plasma-accessible carbonic anhydrase (paCA) at the tissues; the result is a large arterial-venous pH shift that greatly enhances O 2 unloading from pH-sensitive Hb. However, RBC intracellular pH (pH i ) must recover during venous transit (31-90 s), to enable O 2 -loading at the gills. The halftimes (t 1/2 ) and magnitudes of RBC β-adrenergic stimulation, short-circuiting with paCA and recovery of RBC pH i , were assessed in vitro, on rainbow trout whole blood, and using changes in closed-system PO 2 as a sensitive indicator for changes in RBC pH i . In addition, the recovery rate of RBC pH i was assessed in a continuous-flow apparatus that more closely mimics RBC transit though the circulation. Results indicate that: i) the t 1/2 of CA short-circuiting is likely within the residence time of blood in the capillaries; ii) the t 1/2 of RBC pH i recovery is 17 s and within the time of RBC venous transit; and iii) after short-circuiting RBCs re-establish the initial H + gradient across the membrane and can potentially undergo repeated cycles of short-circuiting and recovery. Thus, teleosts have evolved a system that greatly enhances O 2 unloading from pH-sensitive Hb at the tissues, while protecting O 2 loading at the gills; the resulting increase in O 2 transport per unit of blood flow may enable the tremendous athletic ability of salmonids.

Non-invasive MRI measurements of venous oxygenation, oxygen extraction fraction and oxygen consumption in neonates.

PubMed

De Vis, J B; Petersen, E T; Alderliesten, T; Groenendaal, F; de Vries, L S; van Bel, F; Benders, M J N L; Hendrikse, J

2014-07-15

Brain oxygen consumption reflects neuronal activity and can therefore be used to investigate brain development or neuronal injury in neonates. In this paper we present the first results of a non-invasive MRI method to evaluate whole brain oxygen consumption in neonates. For this study 51 neonates were included. The T1 and T2 of blood in the sagittal sinus were fitted using the 'T2 prepared tissue relaxation inversion recovery' pulse sequence (T2-TRIR). From the T1 and the T2 of blood, the venous oxygenation and the oxygen extraction fraction (OEF) were calculated. The cerebral metabolic rate of oxygen (CMRO2) was the resultant of the venous oxygenation and arterial spin labeling whole brain cerebral blood flow (CBF) measurements. Venous oxygenation was 59±14% (mean±sd), OEF was 40±14%, CBF was 14±5ml/100g/min and CMRO2 was 30±12μmol/100g/min. The OEF in preterms at term-equivalent age was higher than in the preterms and in the infants with hypoxic-ischemic encephalopathy (p<0.01). The OEF, CBF and CMRO2 increased (p<0.01, <0.05 and <0.01, respectively) with postnatal age. We presented an MRI technique to evaluate whole-brain oxygen consumption in neonates non-invasively. The measured values are in line with reference values found by invasive measurement techniques. Preterms and infants with HIE demonstrated significant lower oxygen extraction fraction than the preterms at term-equivalent age. This could be due to decreased neuronal activity as a reflection of brain development or as a result of tissue damage, increased cerebral blood flow due to immature or impaired autoregulation, or could be caused by differences in postnatal age. Copyright © 2014 Elsevier Inc. All rights reserved.

Modeling Platform Dynamics and Physiological Response to Short Arm Centrifugation

DTIC Science & Technology

1994-03-01

the "venous pump." There is no provision for such a muscular pumping action in the current version of the model, thus this effect is not apparent in...VCt; Dick, DE. Difference-Differential Equations for Fluid Flow in Distensible Tubes. IEEE Trans. Bio-Med. Engr. 14(4): 171-177; 1967. 29. Snyder, MF...Flow in Distensible Tube. IEEE Transactions on efo-Nedical C... Engineering. Vol WNE-14, NO. 3, pp 1M1-177. Jut 1967. C... C... Re - 1*SmCPtl(Sepi

First results from experiments performed with the ESA Anthrorack during the D-2 Spacelab mission.

PubMed

Kuipers, A

1996-06-01

In 1993 four astronauts performed physiological experiments on the payload "Anthrorack" during the second German Spacelab mission D-2. The Anthrorack set-up is a Spacelab double rack developed under the management of the European Space Agency. It consists of an ECHO machine, a respiratory monitoring system (gas analyzer with flow meter), a blood centrifuge, an ergometer, a finger blood pressure device, ECG, body impedance measurement device and a respiratory inductance plethysmograph. Experiment-specific equipment was used as well. Nineteen investigators performed experiments in the cardiovascular, pulmonary, fluid-renal and nutritional physiology area. Results on central venous pressure, ocular pressure, vascular resistance, cardiac output, tissue thickness and orthostatic intolerance are presented in the cardiovascular area. In the pulmonary area first results are mentioned on O2 transport perfusion and ventilation distribution and breathing pattern. From the fluid-renal experiments, data from diuresis, sodium excretion and hormonal determinations are given. Finally results from glucose metabolism and nitrogen turnover experiments are presented.

First results from experiments performed with the ESA Anthrorack during the D-2 spacelab mission

NASA Astrophysics Data System (ADS)

Kuipers, A.

1996-06-01

In 1993 four astronauts performed physiological experiments on the payload "Anthrorack" during the second German Spacelab mission D-2. The Anthrorack set-up is a Spacelab double rack developed under the management of the European Space Agency. It consists of an ECHO machine, a respiratory monitoring system (gas analyzer with flow meter), a blood centrifuge, an ergometer, a finger blood pressure device, ECG, body impedance measurement device and a respiratory inductance plethysmograph. Experiment-specific equipment was used as well. Nineteen investigators performed experiments in the cardiovascular, pulmonary, fluid-renal and nutritional physiology area. Results on central venous pressure, ocular pressure, vascular resistance, cardiac output, tissue thickness and orthostatic intolerance are presented in the cardiovascular area. In the pulmonary area first results are mentioned on O 2 transport perfusion and ventilation distribution and breathing pattern. From the fluid-renal experiments, data from diuresis, sodium excretion and hormonal determinations are given. Finally results from glucose metabolism and nitrogen turnover experiments are presented.

Hybrid model of arm for analysis of regional blood oxygenation in non-invasive optical diagnostics

NASA Astrophysics Data System (ADS)

Nowocień, Sylwester; Mroczka, Janusz

2017-06-01

The paper presents a new comprehensive approach to modeling and analysis of processes occurring during the blood flow in the arm's small vessels as well as non-invasive measurement method of mixed venous oxygen saturation. During the work, a meta-analysis of available physiological data was performed and based on its result a hybrid model of forearm vascular tree was proposed. The model, in its structure, takes into account a classical nonlinear hydro-electric analogy in conjunction with light-tissue interaction. Several geometries of arm vascular tree obtained from magnetic resonance angiography (MRA) image were analyzed which allowed to proposed the structure of electrical analog network. Proposed model allows to simulate the behavior of forearm blood flow from the vascular tree mechanics point of view, as well as effects of the impact of cuff and vessel wall mechanics on the recorded photoplethysmographic signals. In particular, it allows to analyze the reaction and anatomical effects in small vessels and microcirculation caused by occlusive maneuver in selected techniques, what was of particular interest to authors and motivation to undertake research in this area. Preliminary studies using proposed model showed that inappropriate selection of occlusion maneuver parameters (e.g. occlusion time, cuff pressure etc.), cause dangerous turbulence of blood flow in the venous section of the vascular tree.

Effects of spaceflight on human calf hemodynamics

NASA Technical Reports Server (NTRS)

Watenpaugh, D. E.; Buckey, J. C.; Lane, L. D.; Gaffney, F. A.; Levine, B. D.; Moore, W. E.; Wright, S. J.; Blomqvist, C. G.

2001-01-01

Chronic microgravity may modify adaptations of the leg circulation to gravitational pressures. We measured resting calf compliance and blood flow with venous occlusion plethysmography, and arterial blood pressure with sphygmomanometry, in seven subjects before, during, and after spaceflight. Calf vascular resistance equaled mean arterial pressure divided by calf flow. Compliance equaled the slope of the calf volume change and venous occlusion pressure relationship for thigh cuff pressures of 20, 40, 60, and 80 mmHg held for 1, 2, 3, and 4 min, respectively, with 1-min breaks between occlusions. Calf blood flow decreased 41% in microgravity (to 1.15 +/- 0.16 ml x 100 ml(-1) x min(-1)) relative to 1-G supine conditions (1.94 +/- 0.19 ml x 100 ml(-1) x min(-1), P = 0.01), and arterial pressure tended to increase (P = 0.05), such that calf vascular resistance doubled in microgravity (preflight: 43 +/- 4 units; in-flight: 83 +/- 13 units; P < 0.001) yet returned to preflight levels after flight. Calf compliance remained unchanged in microgravity but tended to increase during the first week postflight (P > 0.2). Calf vasoconstriction in microgravity qualitatively agrees with the "upright set-point" hypothesis: the circulation seeks conditions approximating upright posture on Earth. No calf hemodynamic result exhibited obvious mechanistic implications for postflight orthostatic intolerance.

The place of Ruscus extract, hesperidin methyl chalcone, and vitamin C in the management of chronic venous disease.

PubMed

Jawien, Arkadiusz; Bouskela, Eliete; Allaert, François A; Nicolaïdes, Andrew N

2017-02-01

Despite continuous improvement in our knowledge and management of chronic venous disease (CVD), certain areas, such as the role of muscarinic receptors in the pathology and treatment of CVD, remain unexplored. The symposium "The place of Ruscus extract, hesperidin methyl chalcone, and vitamin C in the management of CVD", held at the Annual Meeting of the European Venous Forum on 7-9 July 2016 in London, presented an update on the pathophysiology of CVD and highlighted how the combination of Ruscus extract, hesperidin methyl chalcone, and vitamin C (Ruscus/HMC/VitC; Cyclo 3® Fort), may counteract the deleterious processes underlying CVD. The data presented during this symposium are reported here. The pathophysiology of CVD is driven by a complex process involving numerous factors, with the two key players being venous hypertension and the inflammatory response. The cascade of reactions induced by disturbed venous flow, inflammation, and tissue alterations results in the early appearance of symptoms and progressive development of clinical signs of disease. Previous studies have shown that Ruscus extract acts at three levels: on the veins, capillaries and lymphatics, and has anti-inflammatory properties. A series of recent experiments has shed new light on the mechanism of action of the combination of Ruscus/HMC/VitC. The efficacy of Ruscus/HMC/VitC in CVD is supported by clinical studies, while two meta-analyses have confirmed a significant decrease of several symptoms and ankle circumference in response to treatment with this agent, leading to the conclusion that Ruscus/HMC/VitC deserves a Grade A rating.

Experimental study of histological changes in vascular loops according to the duration of the postoperative period: Application in reconstructive microsurgery

PubMed Central

Paulos, Renata Gregorio; Rudelli, Bruno Alves; Filippe, Renee Zon; dos Santos, Gustavo Bispo; Herrera, Ana Abarca; Ribeiro, Andre Araujo; de Rezende, Marcelo Rosa; Hsiang-Wei, Teng; Mattar-Jr, Rames

2017-01-01

OBJECTIVES: To analyze the histological changes observed in venous grafts subjected to arterial blood flow as a function of the duration of the postoperative period to optimize their use in free flap reconstructions. METHOD: Twenty-five rats (7 females and 18 males) underwent surgery. Surgeries were performed on one animal per week. Five weeks after the first surgery, the same five animals were subjected to an additional surgery to assess the presence or absence of blood flow through the vascular loop, and samples were collected for histological analysis. This cycle was performed five times. RESULTS: Of the rats euthanized four to five weeks after the first surgery, no blood flow was observed through the graft in 80% of the cases. In the group euthanized three weeks after the first surgery, no blood flow was observed in 20% of the cases. In the groups euthanized one to two weeks after the first surgery, blood flow through the vascular loop was observed in all animals. Moreover, intimal proliferation tended to increase with the duration of the postoperative period. Two weeks after surgery, intimal proliferation increased slightly, whereas strong intimal proliferation was observed in all rats evaluated five weeks after surgery. CONCLUSION: Intimal proliferation was the most significant change noted in venous grafts as a function of the duration of the postoperative period and was directly correlated with graft occlusion. In cases in which vascular loops are required during free flap reconstruction, both procedures should preferably be performed during the same surgery. PMID:29069256

Contribution of voltage-dependent K+ channels to metabolic control of coronary blood flow

PubMed Central

Berwick, Zachary C.; Dick, Gregory M.; Moberly, Steven P.; Kohr, Meredith C.; Sturek, Michael; Tune, Johnathan D.

2011-01-01

The purpose of this investigation was to test the hypothesis that KV channels contribute to metabolic control of coronary blood flow and that decreases in KV channel function and/or expression significantly attenuate myocardial oxygen supply-demand balance in the metabolic syndrome (MetS). Experiments were conducted in conscious, chronically instrumented Ossabaw swine fed either a normal maintenance diet or an excess calorie atherogenic diet that produces the clinical phenotype of early MetS. Data were obtained under resting conditions and during graded treadmill exercise before and after inhibition of KV channels with 4-aminopyridine (4-AP, 0.3 mg/kg, i.v.). In lean-control swine, 4-AP reduced coronary blood flow ~15% at rest and ~20% during exercise. Inhibition of KV channels also increased aortic pressure (P < 0.01) while reducing coronary venous Po2 (P < 0.01) at a given level of myocardial oxygen consumption (MVo2). Administration of 4-AP had no effect on coronary blood flow, aortic pressure, or coronary venous Po2 in swine with MetS. The lack of response to 4-AP in MetS swine was associated with a ~20% reduction in coronary KV current (P < 0.01) and decreased expression of KV1.5 channels in coronary arteries (P < 0.01). Together, these data demonstrate that KV channels play an important role in balancing myocardial oxygen delivery with metabolism at rest and during exercise-induced increases in MVo2. Our findings also indicate that decreases in KV channel current and expression contribute to impaired control of coronary blood flow in the MetS. PMID:21771599

Experimental study of histological changes in vascular loops according to the duration of the postoperative period: Application in reconstructive microsurgery.

PubMed

Paulos, Renata Gregorio; Rudelli, Bruno Alves; Filippe, Renee Zon; Dos Santos, Gustavo Bispo; Herrera, Ana Abarca; Ribeiro, Andre Araujo; de Rezende, Marcelo Rosa; Hsiang-Wei, Teng; Mattar, Rames

2017-10-01

To analyze the histological changes observed in venous grafts subjected to arterial blood flow as a function of the duration of the postoperative period to optimize their use in free flap reconstructions. Twenty-five rats (7 females and 18 males) underwent surgery. Surgeries were performed on one animal per week. Five weeks after the first surgery, the same five animals were subjected to an additional surgery to assess the presence or absence of blood flow through the vascular loop, and samples were collected for histological analysis. This cycle was performed five times. Of the rats euthanized four to five weeks after the first surgery, no blood flow was observed through the graft in 80% of the cases. In the group euthanized three weeks after the first surgery, no blood flow was observed in 20% of the cases. In the groups euthanized one to two weeks after the first surgery, blood flow through the vascular loop was observed in all animals. Moreover, intimal proliferation tended to increase with the duration of the postoperative period. Two weeks after surgery, intimal proliferation increased slightly, whereas strong intimal proliferation was observed in all rats evaluated five weeks after surgery. Intimal proliferation was the most significant change noted in venous grafts as a function of the duration of the postoperative period and was directly correlated with graft occlusion. In cases in which vascular loops are required during free flap reconstruction, both procedures should preferably be performed during the same surgery.

Comparison of Venous Return Characteristics with Right Ventricular Mechanics During Cephalic Fluid Shift

NASA Technical Reports Server (NTRS)

Elliott, Morgan; Martin, David

2015-01-01

For my summer internship project, I organized a pilot study to analyze the effects of a cephalic fluid shift on venous return and right ventricular mechanics to increase right ventricular and venous knowledge. To accomplish this pilot study, I wrote a testing protocol, obtained Institutional Review Board (IRB) approval, completed subject payment forms, lead testing sessions, and analyzed the data. This experiment used -20deg head down tilt (20 HDT) as the ground based simulation for the fluid shift that occurs during spaceflight and compared it to data obtained from the seated and supine positions. Using echocardiography, data was collected for the right ventricle, hepatic vein, internal jugular vein, external jugular vein, and inferior vena cava. Additionally, non-invasive venous pressure measurements, similar to those soon to be done in-orbit, were collected. It was determined that the venous return from below the heard is increased during 20 HDT, which was supported by increased hepatic vein velocities, increased right ventricular inflow, and increased right ventricular strain at 20 HDT relative to seated values. Jugular veins in the neck undergo an increase in pressure and area, but no significant increase in flow, relative to seated values when a subject is tilted 20 HDT. Contrary to the initial expectations based on this jugular flow, there was no significant increase in central venous pressure, as evidenced by no change in Doppler indices for right arterial pressure or inferior vena cava diameter. It is suspected that these differences in pressure are due to the hydrostatic pressure indifference point shifting during tilt; there is a potential for a similar phenomenon with microgravity. This data will hopefully lead to a more in-depth understanding of the response of the body to microgravity and how those relate to the previously mentioned cardiovascular risk of fluid shift that is associated with spaceflight. These results were presented in greater detail to the Cardiovascular Laboratory and the Space Life Science Summer Institute, which helped me prepare for future graduate school research presentations. This internship allowed me to apply and expand the anatomy, physiology, and mechanics information I learned during my undergraduate degree in Biomedical Engineering to the cardiovascular system with the unique zero gravity perspective. Additionally, I was able to develop skills with data analysis techniques involving speckle tracking for ventricular strain and Doppler waveforms for blood velocities. Additionally, I was able to expand upon my previous work in the Cardiovascular Laboratory by writing a literature review on a data analysis project I completed last summer. Ultimately, this internship and venous relationship comparison project provided me with a significant learning experience and additional skill sets, which are applicable to my goals of attaining a Ph.D. in biomedical engineering with a focus on tissue engineering and the cardiovascular system.

Model of the transient neurovascular response based on prompt arterial dilation

PubMed Central

Kim, Jung Hwan; Khan, Reswanul; Thompson, Jeffrey K; Ress, David

2013-01-01

Brief neural stimulation results in a stereotypical pattern of vascular and metabolic response that is the basis for popular brain-imaging methods such as functional magnetic resonance imagine. However, the mechanisms of transient oxygen transport and its coupling to cerebral blood flow (CBF) and oxygen metabolism (CMRO2) are poorly understood. Recent experiments show that brief stimulation produces prompt arterial vasodilation rather than venous vasodilation. This work provides a neurovascular response model for brief stimulation based on transient arterial effects using one-dimensional convection–diffusion transport. Hemoglobin oxygen dissociation is included to enable predictions of absolute oxygen concentrations. Arterial CBF response is modeled using a lumped linear flow model, and CMRO2 response is modeled using a gamma function. Using six parameters, the model successfully fit 161/166 measured extravascular oxygen time courses obtained for brief visual stimulation in cat cerebral cortex. Results show how CBF and CMRO2 responses compete to produce the observed features of the hemodynamic response: initial dip, hyperoxic peak, undershoot, and ringing. Predicted CBF and CMRO2 response amplitudes are consistent with experimental measurements. This model provides a powerful framework to quantitatively interpret oxygen transport in the brain; in particular, its intravascular oxygen concentration predictions provide a new model for fMRI responses. PMID:23756690

The evolution of anterior sector venous drainage in right lobe living donor liver transplantation: does one technique fit all?

PubMed Central

Tokat, Yaman

2016-01-01

In living donor liver transplantation (LDLT), an adequate hepatic venous outflow constitutes one of the basic principles of a technically successful procedure. The issue of whether the anterior sector (AS) of the right lobe (RL) graft should or should not be routinely drained has been controversial. The aim of this 10-year, single-center, retrospective cohort study was to review the evolution of our hepatic venous outflow reconstruction technique in RL grafts and evaluate the impact of routine AS drainage strategy on the outcome. The study group consisted of 582 primary RL LDLT performed between July 2004 and December 2014. The cases were divided into 3 consecutive periods with different AS venous outflow reconstruction techniques, which included middle hepatic vein (MHV) drainage in Era 1 (n=119), a more selective AS drainage with cryopreserved homologous grafts in Era 2 (n=391), and routine segment 5 and/or 8 oriented AS drainage with synthetic grafts in Era 3 (n=72). Intraoperative portal flow measurement with routine splenic artery ligation (SAL) technique (in RL grafts with a portal flow of ≥ 250 mL/min/100 g liver tissue) was added later in Era 3. These 3 groups were compared in terms of recipient and donor demographics, surgical characteristics and short-term outcome. The rate of AS venous drainage varied from 58.8% in Era 1 and 35.0% in Era 2 to 73.6% in Era 3 (P<0.001). Perioperative mortality rate of recipients significantly decreased over the years (15.1% in Era 1 and 8.7% in Era 2 vs. 2.8% in Era 3, P=0.01). After the addition of SAL technique in the 45 cases, there was only 1 graft loss and no perioperative mortality. One-year recipient survival rate was also significantly higher in Era 3 (79.6% in Era 1 and 86.1% in Era 2 vs. 92.1% in Era 3, P=0.002). Routine AS drainage via segment 5 and/or 8 veins using synthetic grafts is a technique to fit all RL grafts in LDLT. Addition of SAL effectively prevents early graft dysfunction and significantly improves the outcome. PMID:27115010

[Hemopleuritis in closed thoracic injuries and multiple trauma].

PubMed

Kabanov, A N; Astafurov, V N; Blokh, E R

1991-09-01

In examination of 817 patients with closed chest injury and multiple trauma 57% of them were found to have obvious or latent hemopleuritis. According to the character of the primary damage and the developing pathophysiological changes, 3 forms of hemopleuritis were revealed: cardiac, pulmonary, and abdominal. A single complex of symptoms forms finally: pulmonary hypertension, venous stasis in the lungs, right-ventricular cardiac insufficiency. As a result, venous blood escapes through the lymph nodes, mainly those of the right lung, and together with the lymph flows in the dilated lymph vessels of the lungs into the pleural cavity. The differential-diagnostic signs of each form of hemopleuritis are pointed out, the prognostic criteria of their development are revealed, and the pathogenetically substantiated therapy is determined.

Neuroimaging patterns of cerebral hyperperfusion

NASA Astrophysics Data System (ADS)

Semenov, S.; Portnov, Yu; Semenov, A.; Korotkevich, A.; Kokov, A.

2017-08-01

Cerebral hyperperfusion syndrome (CHS) after revascularization is a rare phenomenon associated with post-ischemic (reactive) hyperemia and acute pathological hyperperfusion. First described on perfusion CT as a very often moderate CBF increase, MTT/TTP decrease within 30% like a temporary effect, according to a short-time deterioration of neurological symptoms (vestibular ataxia - 58%, vegetative dysfunction - 100%, asthenic syndrome - 100%) in early postoperative period in patients with cardiac ischemia who had undergone coronary artery bypass surgery. The acute pathological hyperperfusion carotid revascularization is a casuistic phenomenon with two- or three-fold CBV and MTT/TTP increase and high hemorrhage risk. Besides, we detected similar exchanges via perfusion CT called benign hyperemia, which marks extension of MTT/TTP and an increase of CBV from 27% to 48% (average 30%), but with normal CBF-parameters, indicating that venous stasis in acute venous ischemic stroke due cerebral venous sinus-trombosis (68%), only 6% in cardioembolic stroke and appears never in arterial stroke. Territorial coincidence registered for perifocal of necrosis zones of benign hyperemia and vasogenic edema accompanied on MRI (DWI, ADC). Secondary hemorrhagic transformation registered for primary non-hemorrhagic venous stroke in 27%, only in 9% for arterial stroke and in 60% for cardioembolic stroke. Probably, congestion is an increasingly predisposing factor secondary hemorrhaging than necrosis.

Comparative Evaluation of Two Venous Sampling Techniques for the Assessment of Pancreatic Insulin and Zinc Release upon Glucose Challenge.

PubMed

Pillai, Anil Kumar; Silvers, William; Christensen, Preston; Riegel, Matthew; Adams-Huet, Beverley; Lingvay, Ildiko; Sun, Xiankai; Öz, Orhan K

2015-01-01

Advances in noninvasive imaging modalities have provided opportunities to study β cell function through imaging zinc release from insulin secreting β cells. Understanding the temporal secretory pattern of insulin and zinc corelease after a glucose challenge is essential for proper timing of administration of zinc sensing probes. Portal venous sampling is an essential part of pharmacological and nutritional studies in animal models. The purpose of this study was to compare two different percutaneous image-guided techniques: transhepatic ultrasound guided portal vein access and transsplenic fluoroscopy guided splenic vein access for ease of access, safety, and evaluation of temporal kinetics of insulin and zinc release into the venous effluent from the pancreas. Both techniques were safe, reproducible, and easy to perform. The mean time required to obtain desired catheter position for venous sampling was 15 minutes shorter using the transsplenic technique. A clear biphasic insulin release profile was observed in both techniques. Statistically higher insulin concentration but similar zinc release after a glucose challenge was observed from splenic vein samples, as compared to the ones from the portal vein. To our knowledge, this is the first report of percutaneous methods to assess zinc release kinetics from the porcine pancreas.

Comparative Evaluation of Two Venous Sampling Techniques for the Assessment of Pancreatic Insulin and Zinc Release upon Glucose Challenge

PubMed Central

Pillai, Anil Kumar; Silvers, William; Christensen, Preston; Riegel, Matthew; Adams-Huet, Beverley; Lingvay, Ildiko; Sun, Xiankai; Öz, Orhan K.

2015-01-01

Advances in noninvasive imaging modalities have provided opportunities to study β cell function through imaging zinc release from insulin secreting β cells. Understanding the temporal secretory pattern of insulin and zinc corelease after a glucose challenge is essential for proper timing of administration of zinc sensing probes. Portal venous sampling is an essential part of pharmacological and nutritional studies in animal models. The purpose of this study was to compare two different percutaneous image-guided techniques: transhepatic ultrasound guided portal vein access and transsplenic fluoroscopy guided splenic vein access for ease of access, safety, and evaluation of temporal kinetics of insulin and zinc release into the venous effluent from the pancreas. Both techniques were safe, reproducible, and easy to perform. The mean time required to obtain desired catheter position for venous sampling was 15 minutes shorter using the transsplenic technique. A clear biphasic insulin release profile was observed in both techniques. Statistically higher insulin concentration but similar zinc release after a glucose challenge was observed from splenic vein samples, as compared to the ones from the portal vein. To our knowledge, this is the first report of percutaneous methods to assess zinc release kinetics from the porcine pancreas. PMID:26273676

Latest advances in edema

NASA Technical Reports Server (NTRS)

Villavicencio, J. L.; Hargens, A. R.; Pikoulicz, E.

1996-01-01

Basic concepts in the physiopathology of edema are reviewed. The mechanisms of fluid exchange across the capillary endothelium are explained. Interstitial flow and lymph formation are examined. Clinical disorders of tissue and lymphatic transport, microcirculatory derangements in venous disorders, protein disorders, and lymphatic system disorders are explored. Techniques for investigational imaging of the lymphatic system are explained.

Noncontrast magnetic resonance angiography of the hand: improved arterial conspicuity by multidirectional flow-sensitive dephasing magnetization preparation in 3D balanced steady-state free precession imaging.

PubMed

Fan, Zhaoyang; Hodnett, Philip A; Davarpanah, Amir H; Scanlon, Timothy G; Sheehan, John J; Varga, John; Carr, James C; Li, Debiao

2011-08-01

: To develop a flow-sensitive dephasing (FSD) preparative scheme to facilitate multidirectional flow-signal suppression in 3-dimensional balanced steady-state free precession imaging and to validate the feasibility of the refined sequence for noncontrast magnetic resonance angiography (NC-MRA) of the hand. : A new FSD preparative scheme was developed that combines 2 conventional FSD modules. Studies using a flow phantom (gadolinium-doped water 15 cm/s) and the hands of 11 healthy volunteers (6 males and 5 females) were performed to compare the proposed FSD scheme with its conventional counterpart with respect to the signal suppression of multidirectional flow. In 9 of the 11 healthy subjects and 2 patients with suspected vasculitis and documented Raynaud phenomenon, respectively, 3-dimensional balanced steady-state free precession imaging coupled with the new FSD scheme was compared with spatial-resolution-matched (0.94 × 0.94 × 0.94 mm) contrast-enhanced magnetic resonance angiography (0.15 mmol/kg gadopentetate dimeglumine) in terms of overall image quality, venous contamination, motion degradation, and arterial conspicuity. : The proposed FSD scheme was able to suppress 2-dimensional flow signal in the flow phantom and hands and yielded significantly higher arterial conspicuity scores than the conventional scheme did on NC-MRA at the regions of common digitals and proper digitals. Compared with contrast-enhanced magnetic resonance angiography, the refined NC-MRA technique yielded comparable overall image quality and motion degradation, significantly less venous contamination, and significantly higher arterial conspicuity score at digital arteries. : The FSD-based NC-MRA technique is improved in the depiction of multidirectional flow by applying a 2-module FSD preparation, which enhances its potential to serve as an alternative magnetic resonance angiography technique for the assessment of hand vascular abnormalities.

Variation in DVT prophylaxis for adolescent trauma patients: a survey of the Society of Trauma Nurses.

PubMed

O'Brien, Sarah H; Haley, Kathy; Kelleher, Kelly J; Wang, Wei; McKenna, Christine; Gaines, Barbara A

2008-01-01

We performed a survey of the Society of Trauma Nurses to explore current practice patterns for deep venous thrombosis prophylaxis in adolescent trauma patients and analyzed responses from 133 institutions. The majority of adult prophylaxis protocols include older adolescents. Only 41% of adult programs identified patient age as "very" important in prophylaxis decision making. Pelvic fracture, spinal cord injury, and expected immobilization were rated most important. Pharmacologic prophylaxis in 11- to 15-year-olds was infrequent, with 60% of centers using never or rarely. Use was much higher but variable among older adolescents. No consensus on deep venous thrombosis prophylaxis in adolescent trauma emerged from our survey.

Ectopic drainage from the inferior vena cava to the left atrium together with a partial anomalous pulmonary venous connection.

PubMed

Wu, Yuan; Xu, Shuangyue; Guo, Hongwei; Yan, Guoliang; Qi, Zhongquan; Shan, Zhonggui

2014-07-01

We report a case of a 44-year-old male patient with ectopic drainage from the inferior vena cava to the left atrium accompanied by partial anomalous pulmonary venous drainage. After the patient was hospitalized, his diagnosis was confirmed by Doppler echocardiography and angiography. A pericardial patch was used to divert the blood to the atrium. The surgical procedure was successful, and the patient began a rehabilitation program 8 days later. This type of ectopic drainage pattern is an unusual and infrequent clinical finding. The definitive diagnosis should be made by Doppler ultrasound combined with angiography. Copyright © 2014 Elsevier Inc. All rights reserved.

Anatomy and Classification of Gastrorenal and Gastrocaval Shunts

PubMed Central

Sabri, Saher S.; Saad, Wael E. A.

2011-01-01

The gastric varices communicate with gastrorenal and gastrocaval shunts and are classified according to the pattern of venous inflow into three types, which differ in the number and location of the inflow veins. The gastric varices are also classified according to their venous drainage into four different types, reflecting the size and number of collateral veins communicating with the gastric varices and the gastrorenal/gastrocaval shunt. Lastly, the gastric varices are classified according to their appearance on balloon-occluded retrograde venography into five grades representing the degree of opacification of the gastric varices and the collateral veins. Understanding these anatomic classifications is crucial in planning endovascular obliteration of gastric varices. PMID:22942547

The origin of mean arterial and jugular venous blood pressures in giraffes.

PubMed

Mitchell, Graham; Maloney, Shane K; Mitchell, Duncan; Keegan, D James

2006-07-01

Using a mechanical model of the giraffe neck and head circulation consisting of a rigid, ascending, 'carotid' limb, a 'cranial' circulation that could be rigid or collapsible, and a descending, 'jugular' limb that also could be rigid or collapsible, we have analyzed the origin of the high arterial and venous pressures in giraffe, and whether blood flow is assisted by a siphon. When the tubes were rigid and the 'jugular' limb exit was lower than the 'carotid' limb entrance a siphon operated, 'carotid' hydrostatic pressures became more negative, and flow was 3.3 l min(-1) but ceased when the 'cranial' and 'jugular' limbs were collapsible or when the 'jugular' limb was opened to the atmosphere. Pumping water through the model produced positive pressures in the 'carotid' limb similar to those found in giraffe. Applying an external 'tissue' pressure to the 'jugular' tube during pump flow produced the typical pressures found in the jugular vein in giraffe. Constriction of the lowest, 'jugular cuff', portion of the 'jugular' limb showed that the cuff may augment the orthostatic reflex during head raising. Except when all tubes were rigid, pressures were unaffected by a siphon. We conclude that mean arterial blood pressure in giraffes is a consequence of the hydrostatic pressure generated by the column of blood in the neck, that tissue pressure around the collapsible jugular vein produces the known jugular pressures, and that a siphon does not assist flow through the cranial circulation.

Pentoxifylline for treating venous leg ulcers.

PubMed

Jull, Andrew B; Arroll, Bruce; Parag, Varsha; Waters, Jill

2012-12-12

Healing of venous leg ulcers is improved by the use of compression bandaging but some venous ulcers remain unhealed, and some people are unsuitable for compression therapy. Pentoxifylline, a drug which helps blood flow, has been used to treat venous leg ulcers. To assess the effects of pentoxifylline (oxpentifylline or Trental 400) for treating venous leg ulcers, compared with a placebo or other therapies, in the presence or absence of compression therapy. For this fifth update we searched the Cochrane Wounds Group Specialised Register (searched 20 July 2012); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 7); Ovid MEDLINE (2010 to July Week 2 2012); Ovid MEDLINE (In-Process & Other Non-Indexed Citations, July 19, 2012); Ovid EMBASE (2010 to 2012 Week 28); and EBSCO CINAHL (2010 to July 13 2012). Randomised trials comparing pentoxifylline with placebo or other therapy in the presence or absence of compression, in people with venous leg ulcers. One review author extracted and summarised details from eligible trials using a coding sheet. One other review author independently verified data extraction. No new trials were identified for this update. We included twelve trials involving 864 participants. The quality of trials was variable. Eleven trials compared pentoxifylline with placebo or no treatment. Pentoxifylline is more effective than placebo in terms of complete ulcer healing or significant improvement (RR 1.70, 95% CI 1.30 to 2.24). Pentoxifylline plus compression is more effective than placebo plus compression (RR 1.56, 95% CI 1.14 to 2.13). Pentoxifylline in the absence of compression appears to be more effective than placebo or no treatment (RR 2.25, 95% CI 1.49 to 3.39).More adverse effects were reported in people receiving pentoxifylline (RR 1.56, 95% CI 1.10 to 2.22). Nearly three-quarters (72%) of the reported adverse effects were gastrointestinal. Pentoxifylline is an effective adjunct to compression bandaging for treating venous ulcers and may be effective in the absence of compression. The majority of adverse effects were gastrointestinal disturbances.

Congenital portosystemic venous shunt.

PubMed

Papamichail, M; Pizanias, M; Heaton, N

2018-03-01

Congenital portosystemic venous shunts are rare developmental anomalies resulting in diversion of portal flow to the systemic circulation and have been divided into extra- and intrahepatic shunts. They occur during liver and systemic venous vascular embryogenesis and are associated with other congenital abnormalities. They carry a higher risk of benign and malignant liver tumors and, if left untreated, can result in significant medical complications including systemic encephalopathy and pulmonary hypertension. This article reviews the various types of congenital portosystemic shunts and their anatomy, pathogenesis, symptomatology, and timing and options of treatment. What is Known: • The natural history and basic management of this rare congenital anomaly are presented. What is New: • This paper is a comprehensive review; highlights important topics in pathogenesis, clinical symptomatology, and treatment options; and proposes an algorithm in the management of congenital portosystemic shunt disease in order to provide a clear idea to a pediatrician. An effort has been made to emphasize the indications for treatment in the children population and link to the adult group by discussing the consequences of lack of treatment or delayed diagnosis.

Effects of Changes in Arterial Carbon Dioxide and Oxygen Partial Pressures on Cerebral Oximeter Performance.

PubMed

Schober, Andrew; Feiner, John R; Bickler, Philip E; Rollins, Mark D

2018-01-01

Cerebral oximetry (cerebral oxygen saturation; ScO2) is used to noninvasively monitor cerebral oxygenation. ScO2 readings are based on the fraction of reduced and oxidized hemoglobin as an indirect estimate of brain tissue oxygenation and assume a static ratio of arterial to venous intracranial blood. Conditions that alter cerebral blood flow, such as acute changes in PaCO2, may decrease accuracy. We assessed the performance of two commercial cerebral oximeters across a range of oxygen concentrations during normocapnia and hypocapnia. Casmed FORE-SIGHT Elite (CAS Medical Systems, Inc., USA) and Covidien INVOS 5100C (Covidien, USA) oximeter sensors were placed on 12 healthy volunteers. The fractional inspired oxygen tension was varied to achieve seven steady-state levels including hypoxic and hyperoxic PaO2 values. ScO2 and simultaneous arterial and jugular venous blood gas measurements were obtained with both normocapnia and hypocapnia. Oximeter bias was calculated as the difference between the ScO2 and reference saturation using manufacturer-specified weighting ratios from the arterial and venous samples. FORE-SIGHT Elite bias was greater during hypocapnia as compared with normocapnia (4 ± 9% vs. 0 ± 6%; P < 0.001). The INVOS 5100C bias was also lower during normocapnia (5 ± 15% vs. 3 ± 12%; P = 0.01). Hypocapnia resulted in a significant decrease in mixed venous oxygen saturation and mixed venous oxygen tension, as well as increased oxygen extraction across fractional inspired oxygen tension levels (P < 0.0001). Bias increased significantly with increasing oxygen extraction (P < 0.0001). Changes in PaCO2 affect cerebral oximeter accuracy, and increased bias occurs with hypocapnia. Decreased accuracy may represent an incorrect assumption of a static arterial-venous blood fraction. Understanding cerebral oximetry limitations is especially important in patients at risk for hypoxia-induced brain injury, where PaCO2 may be purposefully altered.

Time-dependent hardening of blood clots quantitatively measured in vivo with shear-wave ultrasound imaging in a rabbit model of venous thrombosis.

PubMed

Mfoumou, Etienne; Tripette, Julien; Blostein, Mark; Cloutier, Guy

2014-02-01

Provide in vivo blood clot hardening evolution with ultrasound using supersonic imaging of shear waves. We conducted a prospective study in flow stasis-induced venous thrombosis within jugular veins of white female New Zealand rabbits. Blood clot elasticity was noninvasively measured in vivo using the Young's modulus (in kilopascals), on a 2-hour and a 2-week periods after thrombus induction. Monitoring was followed by a necropsy and ex vivo mechanical characterization to validate the existence and elasticity of explanted thrombi. Stagnant blood in the region of interest underwent clotting and progressive hardening with thrombus aging. The mean Young's moduli varied from 1.0 ± 0.6 kPa (at 10 min) to 5.3 ± 1.6 kPa (at 2 hours), then to 25.0 ± 6.8 kPa (at 14 days) post-surgery. Mean ex vivo moduli of 6.2 ± 0.7 kPa at 2 hours and 29.0 ± 2.4 kPa at 2 weeks agreed with in vivo measures. Supersonic imaging of shear waves provides consistent quantitative non-invasive elasticity measurements not available with standard compression ultrasound imaging for diagnosing and following venous thromboembolism. This information translatable to humans could aid in determining whether continued anticoagulant treatment is necessary, especially in the setting of unprovoked venous thromboembolism. Copyright © 2013 Elsevier Ltd. All rights reserved.

Platelet endothelial cell adhesion molecule 1 deficiency misguides venous thrombus resolution.

PubMed

Kellermair, Joerg; Redwan, Bassam; Alias, Sherin; Jabkowski, Joerg; Panzenboeck, Adelheid; Kellermair, Lukas; Winter, Max P; Weltermann, Ansgar; Lang, Irene M

2013-11-07

Platelet endothelial cell adhesion molecule 1 (PECAM-1) is involved in leukocyte migration and angiogenesis, which are key components of venous thrombus resolution. This study investigated the effect of PECAM-1 deficiency on thrombus resolution in FVB/n mice and the extent to which levels of soluble PECAM-1 (sPECAM-1) correlate with delayed thrombus resolution in humans after acute symptomatic deep vein thrombosis (DVT). In a mouse stagnant flow venous thrombosis model Pecam-1(-/-) thrombi were larger, persisted for longer periods of time, and displayed attenuated macrophage invasion and decreased vessel formation in the presence of increased fibrosis. In humans, higher levels of truncated plasma sPECAM-1 possibly cleaved from cell surfaces, were found in patients with delayed thrombus resolution (assessed via duplex-based thrombus scoring) relative to those whose thrombi resolved (median, 25th/75th percentile): 92.5 (87.7/103.4) ng/mL vs 71.5 (51.1/81.0) ng/mL; P < .001. Furthermore, unresolved human deep vein thrombus specimens stained positively with antibodies specific for the extracellular, but not the cytoplasmic domain of PECAM-1, consistent with accumulation of cleaved PECAM-1. Our data suggest a regulatory role of PECAM-1 in venous thrombus resolution and suggest a predictive value of sPECAM-1 for postthrombotic syndrome (PTS) after acute DVT.

Crystalloids versus colloids for goal-directed fluid therapy in major surgery

PubMed Central

Hiltebrand, Luzius B; Kimberger, Oliver; Arnberger, Michael; Brandt, Sebastian; Kurz, Andrea; Sigurdsson, Gisli H

2009-01-01

Introduction Perioperative hypovolemia arises frequently and contributes to intestinal hypoperfusion and subsequent postoperative complications. Goal-directed fluid therapy might reduce these complications. The aim of this study was to compare the effects of goal-directed administration of crystalloids and colloids on the distribution of systemic, hepatosplanchnic, and microcirculatory (small intestine) blood flow after major abdominal surgery in a clinically relevant pig model. Methods Twenty-seven pigs were anesthetized and mechanically ventilated and underwent open laparotomy. They were randomly assigned to one of three treatment groups: the restricted Ringer lactate (R-RL) group (n = 9) received 3 mL/kg per hour of RL, the goal-directed RL (GD-RL) group (n = 9) received 3 mL/kg per hour of RL and intermittent boluses of 250 mL of RL, and the goal-directed colloid (GD-C) group (n = 9) received 3 mL/kg per hour of RL and boluses of 250 mL of 6% hydroxyethyl starch (130/0.4). The latter two groups received a bolus infusion when mixed venous oxygen saturation was below 60% ('lockout' time of 30 minutes). Regional blood flow was measured in the superior mesenteric artery and the celiac trunk. In the small bowel, microcirculatory blood flow was measured using laser Doppler flowmetry. Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes. Results After 4 hours of treatment, arterial blood pressure, cardiac output, mesenteric artery flow, and mixed oxygen saturation were significantly higher in the GD-C and GD-RL groups than in the R-RL group. Microcirculatory flow in the intestinal mucosa increased by 50% in the GD-C group but remained unchanged in the other two groups. Likewise, tissue oxygen tension in the intestine increased by 30% in the GD-C group but remained unchanged in the GD-RL group and decreased by 18% in the R-RL group. Mesenteric venous glucose concentrations were higher and lactate levels were lower in the GD-C group compared with the two crystalloid groups. Conclusions Goal-directed colloid administration markedly increased microcirculatory blood flow in the small intestine and intestinal tissue oxygen tension after abdominal surgery. In contrast, goal-directed crystalloid and restricted crystalloid administrations had no such effects. Additionally, mesenteric venous glucose and lactate concentrations suggest that intestinal cellular substrate levels were higher in the colloid-treated than in the crystalloid-treated animals. These results support the notion that perioperative goal-directed therapy with colloids might be beneficial during major abdominal surgery. PMID:19302713

Influence of dynamic flow conditions on adsorbed plasma protein corona and surface-induced thrombus generation on antifouling brushes.

PubMed

Yu, Kai; Andruschak, Paula; Yeh, Han Hung; Grecov, Dana; Kizhakkedathu, Jayachandran N

2018-06-01

The information regarding the nature of protein corona (and its changes) and cell binding on biomaterial surface under dynamic conditions is critical to dissect the mechanism of surface-induced thrombosis. In this manuscript, we investigated the nature of protein corona and blood cell binding in heparinized recalcified human plasma, platelet rich plasma and whole blood on three highly hydrophilic antifouling polymer brushes, (poly(N, N-dimethylacrylamide) (PDMA), poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly[N-(2-hydroxypropyl) methacrylamide] (PHPMA) using an in vitro blood loop model at comparable arterial and venous flow, and static conditions. A fluid dynamics model was used initially to better understand the resulting flow patterns in a vertical channel containing the substrates to arrive at the placement of the substrates within the blood loop. The protein binding on the brush modified substrates was determined using ellipsometry, fluorescence microscopy and the nature of the protein corona was investigated using mass spectrometry based proteomics. The flow elevated fouling on brush coated surface from blood. The extent of plasma protein adsorption and platelet adhesion onto PDMA brush was lower than other surfaces in both static and flow conditions. The profiles of adsorbed protein corona showed strong dependence on the test conditions (static vs. flow), and the chemistry of the polymer brushes. Specially, the PDMA brush under flow conditions was more enriched with coagulation proteins, complement proteins, vitronectin and fibronectin but was less enriched with serum albumin. Apolipoprotein B-100 and complement proteins were the most abundant proteins seen on PMPC and PHPMA surfaces under both flow and static conditions, respectively. Unlike PDMA brush, the flow conditions did not affect the composition of protein corona on PMPC and PHPMA brushes. The nature of the protein corona formed in flow conditions influenced the platelet and red blood cell binding. The dependence of shear stress on platelet adhesion from platelet rich plasma and whole blood highlights the contribution of red blood cells in enhancing platelet adhesion on the surface under high shear condition. Copyright © 2018 Elsevier Ltd. All rights reserved.

Some potential blood flow experiments for space

NASA Technical Reports Server (NTRS)

Cokelet, G. R.; Meiselman, H. J.; Goldsmith, H. L.

1979-01-01

Blood is a colloidal suspension of cells, predominantly erythrocytes, (red cells) in an aqueous solution called plasma. Because the red cells are more dense than the plasma, and because they tend to aggregate, erythrocyte sedimentation can be significant when the shear stresses in flowing blood are small. This behavior, coupled with equipment restrictions, has prevented certain definitive fluid mechanical studies from being performed with blood in ground-based experiments. Among such experiments, which could be satisfactorily performed in a microgravity environment, are the following: (1) studies of blood flow in small tubes, to obtain pressure-flow rate relationships, to determine if increased red cell aggregation can be an aid to blood circulation, and to determine vessel entrance lengths, and (2) studies of blood flow through vessel junctions (bifurcations), to obtain information on cell distribution in downstream vessels of (arterial) bifurcations, and to test flow models of stratified convergent blood flows downstream from (venous) bifurcations.

Jugular veins in transient global amnesia: innocent bystanders.

PubMed

Baracchini, Claudio; Tonello, Simone; Farina, Filippo; Viaro, Federica; Atzori, Matteo; Ballotta, Enzo; Manara, Renzo

2012-09-01

Transient global amnesia (TGA) has been associated with an increased prevalence of internal jugular valve insufficiency and many patients report Valsalva-associated maneuvers before TGA onset. These findings have led to the assumption of hemodynamic alterations in intracranial veins inducing focal hippocampal ischemia. We investigated this hypothesis in patients with TGA and control subjects. Seventy-five patients with TGA and 75 age- and sex-matched healthy subjects were enrolled into a cross-sectional study. Extracranial and transcranial high-resolution venous echo-color-Doppler sonography was performed blindly in all patients and control subjects. Blood flow direction and velocities were recorded at the internal jugular veins, basal veins of Rosenthal, and vein of Galen, both at rest and during Valsalva-associated maneuvers. Mean age of patients with TGA was 60.3±8.0 years (median, 60 years; range, 44-78 years); 44 (59%) were female (female/male ratio: 1.42). Internal jugular valve insufficiency (left, right, or bilateral) was found to be more frequent in patients with TGA than in control subjects: 53 (70.7%) versus 22 (29.3%; P<0.05). Blood flow velocities in the deep cerebral veins of patients with TGA did not differ from control subjects both at rest and during Valsalva-associated maneuvers. Intracranial venous reflux was neither observed in patients with TGA nor in control subjects despite unilateral or bilateral internal jugular valve insufficiency during prolonged and maximal Valsalva-associated maneuvers. This study, although confirming the association between TGA and internal jugular valve insufficiency, challenges the hypothesis that cerebral venous congestion plays a significant role in the pathogenesis of TGA.

Laser treatment of oral vascular malformations

NASA Astrophysics Data System (ADS)

Romeo, U.; Gaimari, G.; Mohsen, M.; Tenore, G.; Palaia, G.

2014-01-01

Oral Vascular Malformations (OVM) are congenital anomalies characterized by morph-structural and/or functional changes of nature in severity and extension. OVM can affect any type of vessels arterial, venous or lymphatic and any capillary or anatomical. They are divided into two categories: low and high flow. In this study were treated 40 patients with OVM with a range size from 2 mm to 44 mm; they were subjected to clinical examination supported by Colour-Doppler Ultrasound instrumental examination and only for doubt cases the Magnetic Resonance Imaging (MRI) was prescribed. Only low flow venous and capillary malformations were treated by GaAlAs laser (Wiser®, Lambda, Brindole,Italy, 980nm) and KTP laser (SmartLite®, DEKA, Florence, Italy, 532nm) with two different techniques: the Transmucosal Thermophotocoagulation (TMT) and the Intralesional Photocoagulation (ILP). These techniques permitted a good control of haemostasis, avoiding bleeding both during surgery and in the postoperative. It is obtained an excellent and good healing respectively in 10% and 60% of cases, a moderate and poor resolution respectively in 22.5% and 7.5% of cases. A clear diagnosis allowed the management of Venous malformations (VM) by laser devices with wavelengths highly absorbed in haemoglobin in safety and efficacy and according to the principles of minimal invasive surgery. The aim of this study was to verify if the laser is effective in the treatment of OVM for the purpose of the clinical findings and the postoperative course. The Authors concluded that the laser can be considered the "gold standard" for treating OVM.

High-Flow Vascular Malformation in the Sigmoid Mesentery Successfully Treated with a Combination of Transarterial and Transvenous Embolization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamo, Minobu, E-mail: kamomino@luke.ac.jp; Yagihashi, Kunihiro; Okamoto, Takeshi

Mesenteric high-flow vascular malformation can cause various clinical symptoms and demand specific therapeutic interventions owing to its peculiar hemodynamics. We report a case of high-flow vascular malformation in the sigmoid mesentery which presented with ischemic colitis. The main trunk of the inferior mesenteric vein was occluded. After partially effective transarterial embolization, transvenous embolization was performed using a microballoon catheter advanced to the venous component of the lesion via the marginal vein. Complete occlusion of the lesion was achieved. Combination of transarterial and transvenous embolization may allow us to apply endovascular treatment to a wider variety of high-flow lesions in themore » area and possibly avoid the bowel resection.« less

[Sequence of venous blood flow alterations in patients after recently endured acute thrombosis of lower-limb deep veins based on the findings of ultrasonographic duplex scanning].

PubMed

Tarkovskiĭ, A A; Zudin, A M; Aleksandrova, E S

2009-01-01

This study was undertaken to investigate the sequence of alterations in the venous blood flow to have occurred within the time frame of one year after sustained acute thrombosis of the lower-limb deep veins, which was carried out using the standard technique of ultrasonographic duplex scanning. A total of thirty-two 24-to-62-year-old patients presenting with newly onset acute phlebothrombosis were followed up. All the patients were sequentially examined at 2 days, 3 weeks, 3 months, 6 months and 12 months after the manifestation of the initial clinical signs of the disease. Amongst the parameters to determine were the patency of the deep veins and the condition of the valvular apparatus of the deep, superficial and communicant veins. According to the obtained findings, it was as early as at the first stage of the phlebohaemodynamic alterations after the endured thrombosis, i. e., during the acute period of the disease, that seven (21.9%) patients were found to have developed valvular insufficiency of the communicant veins of the cms, manifesting itself in the formation of a horizontal veno-venous reflux, and 6 months later, these events were observed to have occurred in all the patients examined (100%). Afterwards, the second stage of the phlebohaemodynamic alterations was, simultaneously with the process of recanalization of the thrombotic masses in the deep veins, specifically characterized by the formation of valvular insufficiency of the latter, manifesting itself in the form of the development of a deep vertical veno-venous reflux, which was revealed at month six after the onset of the disease in 56.3% of the examined subjects, to be then observed after 12 months in 93.8% of the patients involved. Recanalization of thrombotic masses was noted to commence 3 months after the onset of thrombosis in twelve (37.5%) patients, and after 12 months it was seen to ensue in all the patients (100%), eventually ending in complete restoration of the patency of the affected veins (to have occurred in 25% of the cases). Of special interest was the finding that insufficiency of the ostial valve of the great saphenous vein, manifesting itself by a superficial vertical veno-venous reflux, was revealed only in two (6.25%) patients examined 12 months after the onset of the disease, which may be regarded as the third stage of the phlebohaemodynamic alterations. That low prevalence and no evidence of varicose transformation of superficial veins appear to suggest an important part they play in compensation of the venous outflow from the extremity affected.

Observing and Understanding Arterial and Venous Circulation Differences in a Physiology Laboratory Activity

ERIC Educational Resources Information Center

Altermann, Caroline; Gonçalves, Rithiele; Lara, Marcus Vinícius S.; Neves, Ben-Hur S.; Mello-Carpes, Pâmela B.

2015-01-01

The purpose of the present article is to describe three simple practical experiments that aim to observe and discuss the anatomic and physiological functions and differences between arteries and veins as well as the alterations observed in skin blood flow in different situations. For this activity, students were divided in small groups. In each…

Measurement of retinal blood flow in normal Chinese-American subjects by Doppler Fourier-domain optical coherence tomography.

PubMed

Srinivas, Sowmya; Tan, Ou; Wu, Shuang; Nittala, Muneeswar Gupta; Huang, David; Varma, Rohit; Sadda, SriniVas R

2015-02-10

To measure total retinal blood flow (TRBF) in normal, healthy Chinese Americans by using semi-automated analysis of Doppler Fourier-domain optical coherence tomography (FD-OCT) scans. Two hundred sixty-six normal, healthy Chinese-American participants (266 eyes) were enrolled from The Chinese American Eye Study. All participants underwent complete ophthalmic examination, including best-corrected visual acuity, indirect ophthalmoscopy, and Doppler FD-OCT imaging, using the circumpapillary double circular scan protocol. Total retinal blood flow and other vascular parameters (e.g., venous and arterial cross-sectional area and their velocities) were calculated by using Doppler OCT of Retinal Circulation software. Associations between TRBF and other clinical parameters were assessed by using bivariate correlations and linear regression. The mean age of study participants was 57.40 ± 5.60 (range, 50-82) years. The mean TRBF was 49.34 ± 10.08 (range, 27.17-78.08, 95% confidence interval: 25.98-69.10) μL/min. The mean venous area was 0.0548 (±0.0084) mm(2). Superior retinal hemispheric blood flow (25.50 ± 6.62 μL/min) was slightly greater than inferior retinal hemispheric blood flow (23.84 ± 7.19 μL/min, P = 0.008). The mean flow velocity was 15.16 ± 3.12 mm/s. There was a weak but significant negative correlation between TRBF and age (r = -0.15, P = 0.012). No significant correlation was found between TRBF and axial length (r = 0.11, P = 0.08). Retinal blood flow was not significantly correlated with any other clinical parameters, including body mass index, systolic blood pressure, diastolic blood pressure, and intraocular pressure. Normal Doppler OCT-derived total retinal blood values in a Chinese-American population showed considerable variability, some of which was explained by age. These observations should help design future studies evaluating TRBF in populations with eye disease. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

In Vivo Evaluation of Active and Passive Physiological Control Systems for Rotary Left and Right Ventricular Assist Devices.

PubMed

Gregory, Shaun D; Stevens, Michael C; Pauls, Jo P; Schummy, Emma; Diab, Sara; Thomson, Bruce; Anderson, Ben; Tansley, Geoff; Salamonsen, Robert; Fraser, John F; Timms, Daniel

2016-09-01

Preventing ventricular suction and venous congestion through balancing flow rates and circulatory volumes with dual rotary ventricular assist devices (VADs) configured for biventricular support is clinically challenging due to their low preload and high afterload sensitivities relative to the natural heart. This study presents the in vivo evaluation of several physiological control systems, which aim to prevent ventricular suction and venous congestion. The control systems included a sensor-based, master/slave (MS) controller that altered left and right VAD speed based on pressure and flow; a sensor-less compliant inflow cannula (IC), which altered inlet resistance and, therefore, pump flow based on preload; a sensor-less compliant outflow cannula (OC) on the right VAD, which altered outlet resistance and thus pump flow based on afterload; and a combined controller, which incorporated the MS controller, compliant IC, and compliant OC. Each control system was evaluated in vivo under step increases in systemic (SVR ∼1400-2400 dyne/s/cm(5) ) and pulmonary (PVR ∼200-1000 dyne/s/cm(5) ) vascular resistances in four sheep supported by dual rotary VADs in a biventricular assist configuration. Constant speed support was also evaluated for comparison and resulted in suction events during all resistance increases and pulmonary congestion during SVR increases. The MS controller reduced suction events and prevented congestion through an initial sharp reduction in pump flow followed by a gradual return to baseline (5.0 L/min). The compliant IC prevented suction events; however, reduced pump flows and pulmonary congestion were noted during the SVR increase. The compliant OC maintained pump flow close to baseline (5.0 L/min) and prevented suction and congestion during PVR increases. The combined controller responded similarly to the MS controller to prevent suction and congestion events in all cases while providing a backup system in the event of single controller failure. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Regulation of human retinal blood flow by endothelin-1.

PubMed

Polak, Kaija; Luksch, Alexandra; Frank, Barbara; Jandrasits, Kerstin; Polska, Elzbieta; Schmetterer, Leopold

2003-05-01

There is evidence from in vitro and animal studies that endothelin is a major regulator of retinal blood flow. We set out to characterize the role of the endothelin-system in the blood flow control of the human retina. Two studies in healthy subjects were performed. The study design was randomized, placebo-controlled, double-masked, balanced, two-way crossover in protocol A and three way-way crossover in protocol B. In protocol A 18 healthy male subjects received intravenous endothelin-1 (ET-1) in a dose of 2.5 ng kg (-1)min(-1) for 30 min or placebo on two different study days and retinal vessel diameters were measured. In protocol B 12 healthy male subjects received ET-1 in stepwise increasing doses of 0, 1.25, 2.5 and 5 ng kg (-1)min(-1) (each infusion step over 20 min) in co-infusion with the specific ET(A)-receptor antagonist BQ123 (60 microg min (-1)) or placebo or BQ123 alone investigating retinal vessel diameters, retinal blood velocity and retinal blood flow. Measurements of retinal vessel size were done with the Zeiss retinal vessel analyzer. Measurements of blood velocities were done with bi-directional laser Doppler velocimetry. From these measurements retinal blood flow was calculated. In protocol A exogenous ET-1 tended to decrease retinal arterial diameter, but this effect was not significant versus placebo. No effect on retinal venous diameter was seen. In protocol B retinal venous blood velocity and retinal blood flow was significantly reduced after administration of exogenous ET-1. These effects were significantly blunted when BQ-123 was co-administered. By contrast, BQ-123 alone had no effect on retinal hemodynamic parameters. Concluding, BQ123 antagonizes the effects of exogenously administered ET-1 on retinal blood flow in healthy subjects. In addition, the results of the present study are compatible with the hypothesis that ET-1 exerts its vasoconstrictor effects in the retina mainly on the microvessels.

Evaluation of multiple modes of oximetry monitoring as an index of splanchnic blood flow in a newborn lamb model of hypoxic, ischemic, and hemorrhagic stress.

PubMed

Applegate, Richard L; Ramsingh, Davinder S; Dorotta, Ihab; Sanghvi, Chirag; Blood, Arlin B

2013-06-01

Early and aggressive treatment of circulatory failure is associated with increased survival, highlighting the need for monitoring methods capable of early detection. Vasoconstriction and decreased oxygenation of the splanchnic circulation are a sentinel response of the cardiovasculature during circulatory distress. Thus, we measured esophageal oxygenation as an index of decreased tissue oxygen delivery caused by three types of ischemic insult, occlusive decreases in mesenteric blood flow, and hemodynamic adaptations to systemic hypoxia and simulated hemorrhagic stress. Five anesthetized lambs were instrumented for monitoring of mean arterial pressure, mesenteric artery blood flow, central venous hemoglobin oxygen saturation, and esophageal and buccal microvascular hemoglobin oxygen saturation (StO2). The sensitivities of oximetry monitoring to detect cardiovascular insult were assessed by observing responses to graded occlusion of the descending aorta, systemic hypoxia due to decreased FIO2, and acute hemorrhage. Decreases in mesenteric artery flow during aortic occlusions were correlated with decreased esophageal StO2 (R = 0.41). During hypoxia, esophageal StO2 decreased significantly within 1 min of initiation, whereas buccal StO2 decreased within 3 min, and central venous saturation did not change significantly. All modes of oximetry monitoring and arterial blood pressure were correlated with mesenteric artery flow during acute hemorrhage. Esophageal StO2 demonstrated a greater decrease from baseline levels as well as a more rapid return to baseline levels during reinfusion of the withdrawn blood. These experiments suggest that monitoring esophageal StO2 may be useful in the detection of decreased mesenteric oxygen delivery as may occur in conditions associated with hypoperfusion or hypoxia.

Dehydration affects cerebral blood flow but not its metabolic rate for oxygen during maximal exercise in trained humans.

PubMed

Trangmar, Steven J; Chiesa, Scott T; Stock, Christopher G; Kalsi, Kameljit K; Secher, Niels H; González-Alonso, José

2014-07-15

Intense exercise is associated with a reduction in cerebral blood flow (CBF), but regulation of CBF during strenuous exercise in the heat with dehydration is unclear. We assessed internal (ICA) and common carotid artery (CCA) haemodynamics (indicative of CBF and extra-cranial blood flow), middle cerebral artery velocity (MCA Vmean), arterial-venous differences and blood temperature in 10 trained males during incremental cycling to exhaustion in the heat (35°C) in control, dehydrated and rehydrated states. Dehydration reduced body mass (75.8 ± 3 vs. 78.2 ± 3 kg), increased internal temperature (38.3 ± 0.1 vs. 36.8 ± 0.1°C), impaired exercise capacity (269 ± 11 vs. 336 ± 14 W), and lowered ICA and MCA Vmean by 12-23% without compromising CCA blood flow. During euhydrated incremental exercise on a separate day, however, exercise capacity and ICA, MCA Vmean and CCA dynamics were preserved. The fast decline in cerebral perfusion with dehydration was accompanied by increased O2 extraction (P < 0.05), resulting in a maintained cerebral metabolic rate for oxygen (CMRO2). In all conditions, reductions in ICA and MCA Vmean were associated with declining cerebral vascular conductance, increasing jugular venous noradrenaline, and falling arterial carbon dioxide tension (P aCO 2) (R(2) ≥ 0.41, P ≤ 0.01) whereas CCA flow and conductance were related to elevated blood temperature. In conclusion, dehydration accelerated the decline in CBF by decreasing P aCO 2 and enhancing vasoconstrictor activity. However, the circulatory strain on the human brain during maximal exercise does not compromise CMRO2 because of compensatory increases in O2 extraction. © 2014 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Dehydration affects cerebral blood flow but not its metabolic rate for oxygen during maximal exercise in trained humans

PubMed Central

Trangmar, Steven J; Chiesa, Scott T; Stock, Christopher G; Kalsi, Kameljit K; Secher, Niels H; González-Alonso, José

2014-01-01

Intense exercise is associated with a reduction in cerebral blood flow (CBF), but regulation of CBF during strenuous exercise in the heat with dehydration is unclear. We assessed internal (ICA) and common carotid artery (CCA) haemodynamics (indicative of CBF and extra-cranial blood flow), middle cerebral artery velocity (MCA Vmean), arterial–venous differences and blood temperature in 10 trained males during incremental cycling to exhaustion in the heat (35°C) in control, dehydrated and rehydrated states. Dehydration reduced body mass (75.8 ± 3 vs. 78.2 ± 3 kg), increased internal temperature (38.3 ± 0.1 vs. 36.8 ± 0.1°C), impaired exercise capacity (269 ± 11 vs. 336 ± 14 W), and lowered ICA and MCA Vmean by 12–23% without compromising CCA blood flow. During euhydrated incremental exercise on a separate day, however, exercise capacity and ICA, MCA Vmean and CCA dynamics were preserved. The fast decline in cerebral perfusion with dehydration was accompanied by increased O2 extraction (P < 0.05), resulting in a maintained cerebral metabolic rate for oxygen (CMRO2). In all conditions, reductions in ICA and MCA Vmean were associated with declining cerebral vascular conductance, increasing jugular venous noradrenaline, and falling arterial carbon dioxide tension () (R2 ≥ 0.41, P ≤ 0.01) whereas CCA flow and conductance were related to elevated blood temperature. In conclusion, dehydration accelerated the decline in CBF by decreasing and enhancing vasoconstrictor activity. However, the circulatory strain on the human brain during maximal exercise does not compromise CMRO2 because of compensatory increases in O2 extraction. PMID:24835170

Evaluation of cerebral oxygenation and perfusion with conversion from an arterial-to-systemic shunt circulation to the bidirectional Glenn circulation in patients with univentricular cardiac abnormalities.

PubMed

Bertolizio, Gianluca; DiNardo, James A; Laussen, Peter C; Polito, Angelo; Pigula, Frank A; Zurakowski, David; Kussman, Barry D

2015-02-01

Superior vena cava pressure after the bidirectional Glenn operation usually is higher than that associated with the preceding shunt-dependent circulation. The aim of the present study was to determine whether the acute elevation in central venous pressure was associated with changes in cerebral oxygenation and perfusion. Single-center prospective, observational cohort study. Academic children's hospital. Infants with single-ventricle lesions and surgically placed systemic-to-pulmonary artery shunts undergoing the bidirectional Glenn operation. Near-infrared spectroscopy and transcranial Doppler sonography were used to measure regional cerebral oxygen saturation and cerebral blood flow velocity. Mean differences in regional cerebral oxygen saturation and cerebral blood flow velocity before anesthetic induction and shortly before hospital discharge were compared using the F-test in repeated measures analysis of variance. In the 24 infants studied, mean cerebral oxygen saturation increased from 49%±2% to 57%±2% (p = 0.007), mean cerebral blood flow velocity decreased from 57±4 cm/s to 47±4 cm/s (p = 0.026), and peak systolic cerebral blood flow velocity decreased from 111±6 cm/s to 99±6 cm/s (p = 0.046) after the bidirectional Glenn operation. Mean central venous pressure was 8±2 mmHg postinduction of anesthesia and 14±4 mmHg on the first postoperative day and was not associated with a change in cerebral perfusion pressure (p = 0.35). The bidirectional Glenn operation in infants with a shunt-dependent circulation is associated with an improvement in cerebral oxygenation, and the lower cerebral blood flow velocity is likely a response of intact cerebral autoregulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model

PubMed Central

Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

2014-01-01

Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in ‘excess’ quantities which were treated as wave-related. Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)). Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e. pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave. PMID:25015922

Hepatic sinusoid is not well-stirred: estimation of the degree of axial mixing by analysis of lobular concentration gradients formed during uptake of thyroxine by the perfused rat liver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisiger, R.A.; Mendel, C.M.; Cavalieri, R.R.

1986-03-01

Two general models have been proposed for predicting the effects of metabolism, protein binding, and plasma flow on the removal of drugs by the liver. These models differ in the degree of plasma mixing assumed to exist within each hepatic sinusoid. The venous equilibrium model treats the sinusoid as a single well-stirred compartment, whereas the sinusoidal model effectively breaks up the sinusoid into a large number of sequentially perfused compartments which do not exchange their contents except through plasma flow. As a consequence, the sinusoidal model, but not the venous equilibrium model, predicts that the concentration of highly extracted drugsmore » will decline as the plasma flows through the hepatic lobule. To determine which of these alternative models best describes the hepatic uptake process, we looked for evidence that concentration gradients are formed during the uptake of (/sup 125/I)thyroxine by the perfused rat liver. Autoradiography of tissue slices after perfusion of the portal vein at physiologic flow rates with protein-free buffer containing (/sup 125/I)thyroxine demonstrated a rapid exponential fall in grain density with distance from the portal venule, declining by half for each 8% of the mean length of the sinusoid. Reversing the direction of perfusate flow reversed the direction of the autoradiographic gradients, indicating that they primarily reflect differences in the concentration of thyroxine within the hepatic sinusoids rather than differences in the uptake capacity of portal and central hepatocytes. Analysis of the data using models in which each sinusoid was represented by different numbers of sequentially perfused compartments (1-20) indicated that at least eight compartments were necessary to account for the magnitude of the gradients seen.« less

[Congenital intrahepatic venous shunt as a cause of hepatic encephalopathy].

PubMed

Cosme Jiménez, A; Bujanda Fernández de Piérola, L; Poch Zapiraín, M; Orcolaga Alba, R; Ojeda Pérez, E; Arenas Miravé, J I

1995-11-01

Macroscopic intrahepatic portosystemic shunts are extremely rare and may be due to liver injury, congenital vascular malformations or pathologic collaterals secondary to portal hypertension. Forty-eight cases have been reported in the literature up to 1994 with 50-60% presenting cerebral manifestations and 40% being associated with cirrhosis. The case of a patient without cirrhosis who was admitted for upper digestive hemorrhage secondary to gastroduodenal ulcer is described. At 48 hours the patient had an episode of hepatic encephalopathy coinciding with bleeding reactivation. Abdominal echography suggested communication between the right portal and suprahepatic veins and posterior angiography confirmed the diagnosis. Color Doppler echography determined shunt and portal vein blood flow. No case of intrahepatic portosystemic venous shunt as a cause of encephalopathy was found to have been reported in the Spanish literature.

Staged single-ventricle palliation in 2011: outcomes and expectations.

PubMed

Petit, Christopher J

2011-01-01

Outcomes for staged palliation for single-ventricle heart disease have improved over the past two decades. As outcomes improve, parental expectations for survival and quality of life have risen accordingly. Nevertheless, the number of interventions and complications these patients must endure remain high. The final surgical destination of the single-ventricle patient, the total cavopulmonary connection (or Fontan operation) successfully separates systemic venous and pulmonary venous blood flow but does so at great cost. Fontan patients remain at significant risk of complications despite what are perceived to be "favorable" hemodynamics. The outcomes in this population are discussed in this review, with particular attention to the history behind our current strategies as well as to recent salient studies. © 2011 Copyright the Author. Congenital Heart Disease © 2011 Wiley Periodicals, Inc.

Optical imaging of intracranial hemorrhages in newborns: modern strategies in diagnostics and direction for future research

NASA Astrophysics Data System (ADS)

Pavlov, A. N.; Semyachkina-Glushkovskaya, O. V.; Lychagov, V. V.; Bibikova, O. A.; Sindeev, S. S.; Pavlova, O. N.; Shuvalova, E. P.; Tuchin, V. V.

2014-05-01

Using Doppler optical coherence tomography (DOCT) we study stress-related intracranial hemorrhages (ICHs) in newborn rats. We investigate a masked stage of ICH development that corresponds to the first 4 h after the stress. We show that this period is characterized by significant changes in the diameter of the sagittal vein and the velocity of the cerebral venous blood flow (CVBF). We discuss diagnostic abilities of wavelet-based methods and consider an adaptive technique allowing us to reveal clearest distinctions in the dynamics of CVBF between normal and stressed newborn rats. Finally, we conclude that the venous insufficiency in newborns and a reduced response of the sagittal vein to adrenaline are related to important prognostic markers of the risk of ICH development.

The Cardiovascular Effects of Morphine THE PERIPHERAL CAPACITANCE AND RESISTANCE VESSELS IN HUMAN SUBJECTS

PubMed Central

Zelis, Robert; Mansour, Edward J.; Capone, Robert J.; Mason, Dean T.

1974-01-01

To evaluate the effects of morphine on the peripheral venous and arterial beds, 69 normal subjects were evaluated before and after the intravenous administration of 15 mg morphine. Venous tone was determined by three independent techniques in 22 subjects. The venous pressure measured in a hand vein during temporary circulatory arrest (isolated hand vein technique) fell from 20.2±1.4 to 13.4±0.9 mm Hg (P < 0.01) 10 min after morphine, indicating that a significant venodilation had occurred. With the acute occlusion technique, morphine induced a reduction in forearm venous tone from 12.8±1.1 to 7.9±2.3 mm Hg/ml/100 ml (P < 0.01). Although forearm venous volume at a pressure of 30 mm Hg (VV[30]) was increased from 2.26±0.17 to 2.55±0.26 ml/100 ml, measured by the equilibration technique, the change was not significant (P > 0.1). Of note is that the initial reaction to morphine was a pronounced venoconstriction, demonstrated during the first 1-2 min after the drug. (Isolated hand vein pressure increased to 37.2±5.4 mm Hg, P < 0.01). This rapidly subsided, and by 5 min a venodilation was evident. Morphine did not attenuate the venoconstrictor response to a single deep breath, mental arithmetic, or the application of ice to the forehead when measured by either the isolated hand vein technique or the equilibration technique. To evaluate the effects of morphine on the peripheral resistance vessels in 47 normal subjects, forearm blood flow was measured plethysmographically before and 10-15 min after the intravenous administration of 15 mg of morphine. Although mean systemic arterial pressure was unchanged, forearm blood flow increased from 2.92±0.28 to 3.96±0.46 ml/min/100 ml (P < 0.01), and calculated vascular resistance fell from 42.4±5.2 to 31.6±3.2 mm Hg/ml/min/100 ml (P < 0.01). When subjects were tilted to the 45° head-up position, morphine did not block the increase in total peripheral vascular resistance that occurs; however, it did significantly attenuate the forearm arteriolar constrictor response (before morphine, + 25.7±5.4; after morphine, + 13.7±5.3 mm Hg/ml/min/100 ml, P < 0.05). However, morphine did not block the post-Valsalva overshoot of blood pressure, nor did it block the increase in forearm vascular resistance produced by the application of ice to the forehead. Similarly, morphine did not block the arteriolar or venoconstrictor effects of intra-arterially administered norepinephrine. Morphine infused into the brachial artery in doses up to 200 μg/min produced no changes in ipsilateral forearm VV[30], forearm blood flow, or calculated forearm resistance. Intra-arterial promethazine, atropine, and propranolol did not block the forearm arteriolar dilator response to intravenous morphine; however, intra-arterial phentolamine abolished the response. These data suggest that in human subjects, morphine induces a peripheral venous and arteriolar dilation by a reflex reduction in sympathetic alpha adrenergic tone. Morphine does not appear to act as a peripheral alpha adrenergic blocking agent but seems to attenuate the sympathetic efferent discharge at a central nervous system level. Images PMID:4612057

A prospective randomised trial of four-layer versus short stretch compression bandages for the treatment of venous leg ulcers.

PubMed Central

Scriven, J. M.; Taylor, L. E.; Wood, A. J.; Bell, P. R.; Naylor, A. R.; London, N. J.

1998-01-01

This trial was undertaken to examine the safety and efficacy of four-layer compared with short stretch compression bandages for the treatment of venous leg ulcers within the confines of a prospective, randomised, ethically approved trial. Fifty-three patients were recruited from a dedicated venous ulcer assessment clinic and their individual ulcerated limbs were randomised to receive either a four-layer bandage (FLB)(n = 32) or a short stretch bandage (SSB)(n = 32). The endpoint was a completely healed ulcer. However, if after 12 weeks of compression therapy no healing had been achieved, that limb was withdrawn from the study and deemed to have failed to heal with the prescribed bandage. Leg volume was measured using the multiple disc model at the first bandaging visit, 4 weeks later, and on ulcer healing. Complications arising during the study were recorded. Data from all limbs were analysed on an intention to treat basis; thus the three limbs not completing the protocol were included in the analysis. Of the 53 patients, 50 completed the protocol. At 1 year the healing rate was FLB 55% and SSB 57% (chi 2 = 0.0, df = 1, P = 1.0). Limbs in the FLB arm of the study sustained one minor complication, whereas SSB limbs sustained four significant complications. Leg volumes reduced significantly after 4 weeks of compression, but subsequent volume changes were insignificant. Ulcer healing rates were not influenced by the presence of deep venous reflux, post-thrombotic deep vein changes nor by ulcer duration. Although larger ulcers took longer to heal, the overall healing rates for large (> 10 cm2) and small (10 cm2 or less) ulcers were comparable. Four-layer and short stretch bandages were equally efficacious in healing venous ulcers independent of pattern of venous reflux, ulcer area or duration. FLB limbs sustained fewer complications than SSB. PMID:9682649

Effect of venous (gut) CO2 loading on intrapulmonary gas fractions and ventilation in the tegu lizard.

PubMed

Ballam, G O; Donaldson, L A

1988-01-01

Studies were conducted to determine regional pulmonary gas concentrations in the tegu lizard lung. Additionally, changes in pulmonary gas concentrations and ventilatory patterns caused by elevating venous levels of CO2 by gut infusion were measured. It was found that significant stratification of lung gases was present in the tegu and that dynamic fluctuations of CO2 concentration varied throughout the length of the lung. Mean FCO2 was greater and FO2 less in the posterior regions of the lung. In the posterior regions gas concentrations remained nearly constant, whereas in the anterior regions large swings were observed with each breath. In the most anterior sections of the lung near the bronchi, CO2 and O2 concentrations approached atmospheric levels during inspiration and posterior lung levels during expiration. During gut loading of CO2, the rate of rise of CO2 during the breathing pause increased. The mean level of CO2 also increased. Breathing rate and tidal volume increased to produce a doubling of VE. These results indicate that the method of introduction of CO2 into the tegu respiratory system determines the ventilatory response. If the CO2 is introduced into the venous blood a dramatic increase in ventilation is observed. If the CO2 is introduced into the inspired air a significant decrease in ventilation is produced. The changes in pulmonary CO2 environment caused by inspiratory CO2 loading are different from those caused by venous CO2 loading. We hypothesize that the differences in pulmonary CO2 environment caused by either inspiratory CO2 loading or fluctuations in venous CO2 concentration act differently on the IPC. The differing response of the IPC to the two methods of CO2 loading is the cause of the opposite ventilatory response seen during either venous or inspiratory loading.

Analysis of Fundus Photography and Fluorescein Angiography in Nonarteritic Anterior Ischemic Optic Neuropathy and Optic Neuritis.

PubMed

Kim, Min Kyung; Kim, Ungsoo Samuel

2016-08-01

We evaluated fundus and fluorescein angiography (FAG) findings and characteristics that can help distinguish nonarteritic anterior ischemic optic neuropathy (NAION) from optic neuritis (ON). Twenty-three NAION patients and 17 ON with disc swelling patients were enrolled in this study. We performed fundus photography and FAG. The disc-swelling pattern, hyperemia grade, presence of splinter hemorrhages, cotton-wool spots, artery/vein ratio and degree of focal telangiectasia were investigated. The FAG findings for each patient were compared with respect to the following features: the pattern of disc leakage in the early phase, arteriovenous (artery/vein) transit time (second), and the presence and pattern of the filling delay. Cotton-wool spots, focal telangiectasia, and venous congestion were more common in the affected eyes of NAION patients. Upon FAG, 76.5% of the patients in the ON group exhibited normal choroidal circulation. However, 56.5% of patients in the NAION group demonstrated abnormal filling defects, such as peripapillary, generalized, or watershed zone filling delays. Fundus findings, including cotton-wool spots, focal telangiectasia, and venous congestion in the affected eye, may be clues that can be used to diagnose NAION. In addition, choroidal insufficiencies on FAG could be also helpful in differentiating NAION from ON.

Usefulness of Doppler assessment of pulmonary vein and left atrial appendage flow following pulmonary vein isolation of chronic atrial fibrillation in predicting recovery of left atrial function.

PubMed

Donal, Erwan; Grimm, Richard A; Yamada, Hirotsugu; Kim, Yong Jin; Marrouche, Nassir; Natale, Andrea; Thomas, James D

2005-04-15

Atrial fibrillation (AF) is a widespread condition that causes significant morbidity and mortality. Recently, pulmonary venous (PV) isolation using radiofrequency ablation has been used successfully to exclude the pulmonary venous ostia, resulting in correction of AF. Further, miniaturized high-frequency ultrasound phased-array transducers currently provide Doppler and 2-dimensional imaging during the ablation procedure. We examined atrial function and its determinants using intracardiac echocardiography before and after PV isolation in 45 patients who had chronic AF (56 +/- 11 years old). PV, left atrial (LA) appendage, and mitral and tricuspid flows were recorded. Recovery of booster pump function (defined by the presence of mitral inflow A wave, LA appendage a-wave, and PV A-reversal wave velocities >10 cm/s) was observed in 39 of 45 patients (86.6%). PV flow systolic wave before and after ablation correlated with the degree of LA booster pump function after PV isolation. An early systolic PV flow peak velocity >57.47 cm/s predicted "good" LA booster pump function recovery with 96% specificity. Diastolic LA appendage emptying in AF correlated (p <0.001) and predicted good LA booster pump function with 92% specificity for velocities >46.4 cm/s. Thus, monitoring LA function during PV isolation for chronic AF is feasible. Most patients recovered LA booster pump function immediately after PV isolation, and the degree of recovery correlated with LA reservoir function. Preserved reservoir function during AF is predictive of satisfactory recovery of booster pump function after PV isolation.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

PubMed

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Distensibility and pressure-flow relationship of the pulmonary circulation. II. Multibranched model.

PubMed

Bshouty, Z; Younes, M

1990-04-01

The contribution of distensibility and recruitment to the distinctive behavior of the pulmonary circulation is not known. To examine this question we developed a multibranched model in which an arterial vascular bed bifurcates sequentially up to 8 parallel channels that converge and reunite at the venous side to end in the left atrium. Eight resistors representing the capillary bed separate the arterial and venous beds. The elastic behavior of capillaries and extra-alveolar vessels was modeled after Fung and Sobin (Circ. Res. 30: 451-490, 1972) and Smith and Mitzner (J. Appl. Physiol. 48: 450-467, 1980), respectively. Forces acting on each component are modified and calculated individually, thus enabling the user to explore the effects of parallel and longitudinal heterogeneities in applied forces (e.g., gravity, vasomotor tone). Model predictions indicate that the contribution of distensibility to nonlinearities in the pressure-flow (P-F) and atrial-pulmonary arterial pressure (Pla-Ppa) relationships is substantial, whereas gravity-related recruitment contributes very little to these relationships. In addition, Pla-Ppa relationships, obtained at a constant flow, have no discriminating ability in identifying the presence or absence of a waterfall along the circulation. The P-F relationship is routinely shifted in a parallel fashion, within the physiological flow range, whenever extra forces (e.g., lung volume, tone) are applied uniformly at one or more branching levels, regardless of whether a waterfall is created. For a given applied force, the magnitude of parallel shift varies with proportion of the circulation subjected to the added force and with Pla.

Lifelong physical activity prevents an age-related reduction in arterial and skeletal muscle nitric oxide bioavailability in humans

PubMed Central

Nyberg, Michael; Blackwell, James R; Damsgaard, Rasmus; Jones, Andrew M; Hellsten, Ylva; Mortensen, Stefan P

2012-01-01

Ageing has been proposed to be associated with increased levels of reactive oxygen species (ROS) that scavenge nitric oxide (NO). In eight young sedentary (23 ± 1 years; Y), eight older lifelong sedentary (66 ± 2 years; OS) and eight older lifelong physically active subjects (62 ± 2 years; OA), we studied the effect of ROS on systemic and skeletal muscle NO bioavailability and leg blood flow by infusion of the antioxidant N-acetylcysteine (NAC). Infusion of NAC increased the bioavailability of NO in OS, as evidenced by an increased concentration of stable metabolites of NO (NOx) in the arterial and venous circulation and in the muscle interstitium. In OA, infusion of NAC only increased NOx concentrations in venous plasma whereas in Y, infusion of NAC did not affect NOx concentrations. Skeletal muscle protein levels of endothelial and neuronal NO synthase were 32% and 24% higher, respectively, in OA than in OS. Exercise at 12 W elicited a lower leg blood flow response that was associated with a lower leg oxygen uptake in OS than in Y. The improved bioavailability of NO in OS did not increase blood flow during exercise. These data demonstrate that NO bioavailability is compromised in the systemic circulation and in the musculature of sedentary ageing humans due to increased oxidative stress. Lifelong physical activity opposes this effect within the trained musculature and in the arterial circulation. The lower blood flow response to leg exercise in ageing humans is not associated with a reduced NO bioavailability. PMID:22890714

Leiomyosarcoma of the Inferior Vena Cava - Radical Resection, Vascular Reconstruction and Challenges: A Case Report and Review of Relevant Literature

PubMed Central

Biswas, Saptarshi; Amin, Arpit; Chaudry, Suhaib; Joseph, Saju

2013-01-01

Leiomyosarcomas of the inferior Vena Cava (IVC) are rare soft tissue sarcomas accounting for only 0.5% of all soft tissue sarcomas in adults with fewer than 300 cases reported. Extraluminal tumor growth along the adventitia of the IVC seems to be the common presentation. Intraluminal tumor growth is rare. The origin of the tumor is divided into three levels in relation to the hepatic and renal veins. The presentations and surgical modalities vary accordingly. Retroperitoneal tumors are often not diagnosed until the disease is at an advanced stage with large tumor growth and involvement of surrounding structures. This is partly because of the nonspecific clinical presentation as well as absence of early symptoms. Most patients present with abdominal or flank pain. Symptoms vary according to the dimensions of the tumor, growth pattern and localization of the tumor. Radical en bloc resection of the affected venous segment remains the only therapeutic option associated with prolonged survival. The goals of surgical management of these tumors include the achievement of local tumor control, maintenance of caval flow, and the prevention of recurrence. The involvement of renal or hepatic veins determines the strategy for vascular reconstruction. Reconstruction of the IVC is not always required, because gradual occlusion of the IVC allows the development of venous collaterals. However, when pararenal leiomyosarcoma of the IVC is present, reconstruction of the IVC and the renal vein is necessary to prevent transient or permanent renal dysfunction. Recent study has shown that radical surgery combined with adjuvant multimodal therapy has improved the cumulative survival rate. We report a case of IVC leiomyosarcoma in a young healthy woman along with details of its diagnostic workup and discussion of the surgical options and reconstruction of caval continuity. PMID:29147340

Contact activation of blood coagulation on a defined kaolin/collagen surface in a microfluidic assay.

PubMed

Zhu, Shu; Diamond, Scott L

2014-12-01

Generation of active Factor XII (FXIIa) triggers blood clotting on artificial surfaces and may also enhance intravascular thrombosis. We developed a patterned kaolin (0 to 0.3 pg/μm(2))/type 1 collagen fibril surface for controlled microfluidic clotting assays. Perfusion of whole blood (treated only with a low level of 4 μg/mL of the XIIa inhibitor, corn trypsin inhibitor) drove platelet deposition followed by fibrin formation. At venous wall shear rate (100 s(-1)), kaolin accelerated onset of fibrin formation by ~100 sec when compared to collagen alone (250 sec vs. 350 sec), with little effect on platelet deposition. Even with kaolin present, arterial wall shear rate (1000 s(-1)) delayed and suppressed fibrin formation compared to venous wall shear rate. A comparison of surfaces for extrinsic activation (tissue factor TF/collagen) versus contact activation (kaolin/collagen) that each generated equal platelet deposition at 100 s(-1) revealed: (1) TF surfaces promoted much faster fibrin onset (at 100 sec) and more endpoint fibrin at 600 sec at either 100 s(-1) or 1000 s(-1), and (2) kaolin and TF surfaces had a similar sensitivity for reduced fibrin deposition at 1000 s(-1) (compared to fibrin formed at 100 s(-1)) despite differing coagulation triggers. Anti-platelet drugs inhibiting P2Y1, P2Y12, cyclooxygenase-1 or activating IP-receptor or guanylate cyclase reduced platelet and fibrin deposition on kaolin/collagen. Since FXIIa or FXIa inhibition may offer safe antithrombotic therapy, especially for biomaterial thrombosis, these defined collagen/kaolin surfaces may prove useful in drug screening tests or in clinical diagnostic assays of blood under flow conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dorsal metacarpal veins: anatomic variation and potential clinical implications.

PubMed

Elmegarhi, Sara S; Amarin, Justin Z; Hadidi, Maher T; Badran, Darwish H; Massad, Islam M; Bani-Hani, Amjad M; Shatarat, Amjad T

2018-03-01

The dorsal metacarpal veins are frequently cannulated. Cannulation success is determined by several variable anatomic features. The objective of this study is to classify, for the first time, the anatomic variants of the dorsal metacarpal veins. In this cross-sectional study, 520 university students and staff were conveniently recruited. The dorsal metacarpal veins in 1040 hands were studied. Venous visibility was enhanced by either tourniquet application or near-infrared illumination. Variant patterns of the dorsal metacarpal veins were classified. The final analysis included 726 hands, for an exclusion rate of 30 %. Eight pattern types were identified. Three anatomic features informed the variation. Bilateral symmetry of the dorsal metacarpal veins was present in 352 participants (83 % of the total). The overall frequency distribution of variants in both hands was similar (P = 0.8). The frequency distribution of variants was subject to sexual dimorphism (P = 0.001), ethnic variation (P < 0.001), and technical variation (P < 0.001). The anatomic variants of the dorsal metacarpal veins were sorted into decreasingly frequent primary, secondary, and tertiary groups. The groups may signify a progressive increase in difficulty of peripheral cannulation, in the mentioned order. As such, primary patterns are the most common and likely the easiest to cannulate, while tertiary patterns are the least common and likely the most difficult to cannulate. The preceding premise, in tandem with the bilateral asymmetry of the veins, is clinically significant. With cannulation difficulty likely signifying an underlying tertiary pattern, the contralateral dorsal metacarpal veins are probabilistically characterized by a primary pattern and are, as such, the easier option for peripheral venous cannulation.

Wound management with compression therapy and topical hemoglobin solution in a patient with Budd-Chiari Syndrome.

PubMed

Babadagi-Hardt, Zeynep; Engels, Peter; Kanya, Susanne

2014-03-31

Although the underlying primary cause of chronic wounds may vary, a common etiology of this is a hypoxic or ischemic status of the affected tissue of the lower extremities. In particular, for rare diseases associated with disturbed blood flow a correlation between cause and effect is often diagnosed inappropriately. As a consequence, chronic wounds may develop and persist for years. We present a case of a patient with chronic venous insufficiency due to an occlusion of the inferior caval vein. Initially, a Budd-Chiari syndrome was diagnosed which is a thrombotic obstruction of the hepatic venous outflow. In addition, the patient developed an obstruction of the inferior caval vein and subsequently a chronic venous insufficiency. As a consequence, chronic leg ulcers developed with a history of more than 7 years. Various wound care approaches were performed without success in wound closure. Finally, a combination of compression therapy and topical application of a hemoglobin solution successfully led to fast and persistent wound closure. Chronic ulcers of the lower limb such as venous leg ulcers, even for patients with rare disorders like Budd-Chiari syndrome, are associated with oxygen supply disturbances resulting in a hypoxic status of the affected tissue. Therefore, an adequate oxygen supply to chronic wounds plays a pivotal role in successful wound healing. Compression therapy in combination with enhancement of the local oxygen supply by topically applied hemoglobin showed marked improvement of wound healing in the presented patient.

Pneumoperitoneum risk prognosis and correction of venous circulation disturbances in laparoscopic surgery. A pilot study.

PubMed

Emeljanov, S I; Fedenko, V V; Levite, E M; Panfilov, S A; Bobrinskaya, I G; Fedorov, A V; Matveev, N L; Evdoshenko, V V; Luosev, S V; Bokarev, V V; Musaeva, S R

1998-10-01

This study was initiated to find a method of determining the prognosis for possible changes in hemodynamic and respiratory parameters in patients with pneumoperitoneum (PP). We devised a model for a pseudopneumoperitoneum (PPP), which is created by encircling the wide pneumochamber on the entire abdomen and inflating it to a preset pressure. To verify the prognostic possibilities of the proposed model, we studied the pneumotachygraphy parameters, noninvasive and invasive monitoring parameters of PPP after induction of anaesthesia, and venous circulation disturbances, as well as the medical effect of the intermittent sequential compression device. In healthy patients, the restrictive lung syndrome did not approach the risky limit. In patients >/=60 years old, this syndrome was very close to the limit. In a number of patients with serious cardiovascular and pulmonary pathology, the pressure of >10 mmHg was considered to be intolerable. Lung compliance, which was the parameter most sensitive to the increased intraabdominal pressure, was 47 +/- 10 at baseline, and 29 +/- 4 (p > 0.05) at both PPP and real PP (14 mmHg). The PPP model is quite similar to the real PP and can be used for preoperative prognosis in laparoscopic surgery. The elevated intraabdominal pressure results in a significant disturbance of venous blood flow in the lower extremities. The use of the device for peristaltic pneumomassage of the lower limbs is effective in correcting negative changes in venous hemodynamics in laparoscopic surgery.

To what extent might N2 limit dive performance in king penguins?

PubMed

Fahlman, A; Schmidt, A; Jones, D R; Bostrom, B L; Handrich, Y

2007-10-01

A mathematical model was used to explore if elevated levels of N2, and risk of decompression sickness (DCS), could limit dive performance (duration and depth) in king penguins (Aptenodytes patagonicus). The model allowed prediction of blood and tissue (central circulation, muscle, brain and fat) N2 tensions (P(N2)) based on different cardiac outputs and blood flow distributions. Estimated mixed venous P(N2) agreed with values observed during forced dives in a compression chamber used to validate the assumptions of the model. During bouts of foraging dives, estimated mixed venous and tissue P(N2) increased as the bout progressed. Estimated mean maximum mixed venous P(N2) upon return to the surface after a dive was 4.56+/-0.18 atmospheres absolute (ATA; range: 4.37-4.78 ATA). This is equivalent to N2 levels causing a 50% DCS incidence in terrestrial animals of similar mass. Bout termination events were not associated with extreme mixed venous N2 levels. Fat P(N2) was positively correlated with bout duration and the highest estimated fat P(N2) occurred at the end of a dive bout. The model suggested that short and shallow dives occurring between dive bouts help to reduce supersaturation and thereby DCS risk. Furthermore, adipose tissue could also help reduce DCS risk during the first few dives in a bout by functioning as a sink to buffer extreme levels of N2.

Influence of using a single facial vein as outflow in full-face transplantation: A three-dimensional computed tomographic study.

PubMed

Rodriguez-Lorenzo, Andres; Audolfsson, Thorir; Wong, Corrine; Cheng, Angela; Arbique, Gary; Nowinski, Daniel; Rozen, Shai

2015-10-01

The aim of this study was to evaluate the contribution of a single unilateral facial vein in the venous outflow of total-face allograft using three-dimensional computed tomographic imaging techniques to further elucidate the mechanisms of venous complications following total-face transplant. Full-face soft-tissue flaps were harvested from fresh adult human cadavers. A single facial vein was identified and injected distally to the submandibular gland with a radiopaque contrast (barium sulfate/gelatin mixture) in every specimen. Following vascular injections, three-dimensional computed tomographic venographies of the faces were performed. Images were viewed using TeraRecon Software (Teracon, Inc., San Mateo, CA, USA) allowing analysis of the venous anatomy and perfusion in different facial subunits by observing radiopaque filling venous patterns. Three-dimensional computed tomographic venographies demonstrated a venous network with different degrees of perfusion in subunits of the face in relation to the facial vein injection side: 100% of ipsilateral and contralateral forehead units, 100% of ipsilateral and 75% of contralateral periorbital units, 100% of ipsilateral and 25% of contralateral cheek units, 100% of ipsilateral and 75% of contralateral nose units, 100% of ipsilateral and 75% of contralateral upper lip units, 100% of ipsilateral and 25% of contralateral lower lip units, and 50% of ipsilateral and 25% of contralateral chin units. Venographies of the full-face grafts revealed better perfusion in the ipsilateral hemifaces from the facial vein in comparison with the contralateral hemifaces. Reduced perfusion was observed mostly in the contralateral cheek unit and contralateral lower face including the lower lip and chin units. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Utility of 16-MDCT angiography for comprehensive preoperative vascular evaluation of laparoscopic renal donors.

PubMed

Raman, Steven S; Pojchamarnwiputh, Suwalee; Muangsomboon, Kobkun; Schulam, Peter G; Gritsch, H Albin; Lu, David S K

2006-06-01

Our objective was to determine the efficacy of 16-MDCT angiography in preoperative evaluation of vascular anatomy of laparoscopic renal donors. Fifty-five consecutive renal donors (25 men and 30 women) underwent 16-MDCT angiography followed by donor nephrectomy. In the arterial and nephrographic phases, images were acquired with 60% overlap and 0.6-mm reconstruction in both phases after 120 mL of iohexol was injected at 4 mL/sec. On a 3D workstation, images were evaluated retrospectively by two abdominal imagers blinded to surgical results with respect to number and branching pattern of renal arteries and major and minor renal veins. These CT angiography results were compared with surgical findings. The surgically confirmed sensitivity of both reviewers (1 and 2) using the MDCT data for detection of renal arteries was 98.5% (65 of 66), and accuracies were 97.0% for reviewer 1 and 95.5% for reviewer 2. Sensitivity and accuracy detection of renal veins was 97% (61 of 63) and 98% (62 of 63) for reviewer 1 and reviewer 2, respectively. Sensitivity and accuracy detection of early arterial bifurcation (< 2 cm from aorta) was 100% (14 of 14), and sensitivity in detection of late venous confluence (< 1.5 cm from aorta) was 100% (8 of 8). All major renal venous variants were identified; reviewer 1 identified 78% (18 of 23) minor venous variants, and reviewer 2 identified 83% (19 of 23) minor venous variants. There were no hemorrhagic complications at surgery. Excellent agreement between reviewers (kappa = 0.92-0.97) was achieved for detection of normal and variant anatomy. 16-MDCT angiography enabled excellent preoperative detection of arterial anatomy and venous laparoscopic donor nephrectomy.

Assessment of diastolic function by tissue Doppler echocardiography: comparison with standard transmitral and pulmonary venous flow

NASA Technical Reports Server (NTRS)

Farias, C. A.; Rodriguez, L.; Garcia, M. J.; Sun, J. P.; Klein, A. L.; Thomas, J. D.

1999-01-01

The objective of this study was to determine the utility of Doppler tissue echocardiography in the evaluation of diastolic filling and in discriminating between normal subjects and those with various stages of diastolic dysfunction. We measured myocardial velocities in 51 patients with various stages of diastolic dysfunction and in 27 normal volunteers. The discriminating power of each of the standard Doppler indexes of left ventricular filling, pulmonary venous flow, and myocardial velocities was determined with the use of Spearman rank correlation and analysis of variance F statistics. Early diastolic myocardial velocity (E(m)) was higher in normal subjects (16.0 +/- 3.8 cm/s) than in patients with either delayed relaxation (n = 15, 7.5 +/- 2.2 cm/s), pseudonormal filling (n = 26, 7.6 +/- 2.3 cm/s), or restrictive filling (n = 10, 7.4 +/- 2.4 cm/s, P <.0001). E(m ) was the best single discriminator between control subjects and patients with diastolic dysfunction (P =.7, F = 64.5). Myocardial velocities assessed by Doppler tissue echocardiography are useful in differentiating patients with normal from those with abnormal diastolic function. Myocardial velocity remains reduced even in those stages of diastolic dysfunction characterized by increased preload compensation.

Pulmonary Arteriovenous Malformations After the Superior Cavopulmonary Shunt: Mechanisms and Clinical Implications

PubMed Central

Kavarana, Minoo N.; Jones, Jeffrey A.; Stroud, Robert E.; Bradley, Scott M.; Ikonomidis, John S.; Mukherjee, Rupak

2015-01-01

Children with functional single ventricle heart disease are commonly palliated down a staged clinical pathway toward a Fontan completion procedure (total cavopulmonary connection). The Fontan physiology is fraught with long term complications associated with lower body systemic venous hypertension, eventually resulting in significant morbidity and mortality. The bidirectional Glenn shunt or superior cavopulmonary connection (SCPC) is commonly the transitional stage in single ventricle surgical management and provides excellent palliation. Some studies have demonstrated lower morbidity and mortality with the SCPC when compared with the Fontan. Unfortunately the durability of the SCPC is significantly limited by the development of pulmonary arteriovenous malformations (PAVMs) which have been commonly attributed to the absence of hepatic venous blood flow and the lack of pulsatile flow to the affected lungs. Abnormal angiogenesis has been suggested as a final common pathway to PAVM development. Understanding these fundamental mechanisms through the investigation of angiogenic pathways associated with the pathogenesis of PAVMs would help to develop medical therapies that could prevent or reverse this complication following SCPC. Such therapies could improve the longevity of the SCPC, potentially eliminate or significantly postpone the Fontan completion with its associated complications, and improve long-term survival in children with single ventricle disease. PMID:24758411

Influence of Slippery Pacemaker Leads on Lead-Induced Venous Occlusion

NASA Astrophysics Data System (ADS)

Yang, Weiguang; Bhatia, Sagar; Obenauf, Dayna; Resse, Max; Esmaily-Moghadam, Mahdi; Feinstein, Jeffrey; Pak, On Shun

2016-11-01

The use of medical devices such as pacemakers and implantable cardiac defibrillators have become commonplace to treat arrhythmias. Pacing leads with electrodes are used to send electrical pulses to the heart to treat either abnormally slow heart rates, or abnormal rhythms. Lead induced vessel occlusion, which is commonly seen after placement of pacemaker or ICD leads, may result in lead malfunction and/or SVC syndrome, and makes lead extraction difficult. The association between the anatomic locations at risk for thrombosis and regions of venous stasis have been reported previously. The computational studies reveal obvious flow stasis in the proximity of the leads, due to the no-slip boundary condition imposed on the lead surface. With the advent of recent technologies capable of creating slippery surfaces that can repel complex fluids including blood, we explore computationally how local flow structures may be altered in the regions around the leads when the no-slip boundary condition on the lead surface is relaxed using various slip lengths. The findings evaluate the possibility of mitigating risks of lead-induced thrombosis and occlusion by implementing novel surface conditions (i.e. theoretical coatings) on the leads.

Venous filling time using air-plethysmography correlates highly with great saphenous vein reflux time using duplex.

PubMed

Lattimer, C R; Azzam, M; Kalodiki, E; Geroulakos, G

2014-03-01

Venous filling time (VFT90) is the time taken to reach 90% of the venous volume in the calf. It is recorded by air-plethysmography (APG(®)) and is assumed to measure global venous reflux duration. However, this has never been confirmed by duplex. The aim of the study was to compare VFT on APG to venous reflux time/duration (RT) measured simultaneously with duplex on the same patients. Twenty-six consecutive patients, M:F = 16:10, age (25-78), C1 = 1, C2 = 4, C3 = 8, C4a = 6, C4b = 4, C5 = 2, C6 = 1, underwent simultaneous APG with duplex. The venous filling index (VFI, mL/second), VFT90 (seconds), great saphenous vein (GSV) RT on duplex, averaged thigh GSV diameter and thigh length (length) between the APG sensor air-cuff and duplex transducer were recorded. The VFT100 was calculated by VFT90/0.9. The additional time taken to fill the thigh was achieved using the VFI, length and deep vein diameter (d), to determine the corrected reflux duration: CRD = VFT100 + (length × πd(2)/4 (1/VFI)). Twenty-five patients are presented. One patient with very mild reflux (VFT90 = 55.9 seconds) had an indeterminate endpoint on duplex and was excluded. The median (range) VFI and GSV diameter was 4.9(1.3-15.5) mL/second and 7(4-17) mm, respectively. The VFT90 and VFT100 both correlated with RT on duplex (Spearman, P < 0.0005) at: r = 0.933, r(2) linear = 0.72 and r = 0.933, r(2) linear = 0.68, respectively. The median (interquartile range) filling time with VFT90 was less than the duplex RT at 24 (16.9) versus 28 (20) seconds respectively, P < 0.0005 (Wilcoxon). The median percentage underestimation improved from 24% to 16% and then 4% using the VFT90, VFT100 and CRD, respectively. This is the first study to compare APG parameters with duplex by performing simultaneous measurements. There was an excellent correlation between the VFT90 versus duplex RT, thereby comparing reverse flow in a single superficial vein against the legs overall venous haemodynamic status. These tests can both be used in the quantification of reflux.

Protective Effects of Micronized Purified Flavonoid Fraction (MPFF) on a Novel Experimental Model of Chronic Venous Hypertension.

PubMed

das Graças C de Souza, Maria; Cyrino, Fatima Zga; de Carvalho, Jorge J; Blanc-Guillemaud, Vanessa; Bouskela, Eliete

2018-05-01

To assess protective effects of micronized purified flavonoid fraction (MPFF) on microcirculation in an original chronic model of hind limb venous hypertension with low blood flow in small animals. Vein ligatures were performed on male hamsters, as follows: A-right femoral vein; A + B-right femoral vein and its right branch; A + C-right femoral vein and its left branch; A + B + C-right femoral and its right and left branches; D-external right iliac vein. In sham operated groups, similar vascular dissections were performed without ligatures. Superficial (epigastric) and central (jugular) venous pressure evaluations were made during a 10 week period. Hamsters subjected to A + B + C and D ligatures were selected for leukocyte rolling and sticking, functional capillary density (FCD), and venular and arteriolar diameter observations. D ligature was selected to evaluate pharmacological treatment efficacy. MPFF (100 mg/kg), concomitant active flavonoids of MPFF (diosmetin, hesperidin, linarin, and isorhoifolin) (10 mg/kg), diosmin (100 mg/kg) or drug vehicle were administered orally during 2 weeks before vein ligature and 6 weeks thereafter. A, A + B and A + C models maintained venous return through collaterals. From the 2 nd to the 10 th weeks after vein ligatures, A + B + C and D models elicited a progressive increase of superficial venous pressure (3.83 ± 0.65 vs. 8.56 ± 0.72 mmHg, p < .001 and 4.13 ± 0.65 vs. 9.35 ± 0.65 mmHg, p < .001, respectively) with significant changes to the microcirculation. As D model significantly increased superficial venous pressure without affecting central venous pressure, it was used to evaluate the long-term effects of treatment. Compared with vehicle, MPFF, concomitant active flavonoids of MPFF, and diosmin, significantly decreased leukocyte-endothelium interaction and prevented FCD reduction. Only MPFF significantly prevented venular enlargement as observed in the vehicle treated group. MPFF was more effective than diosmin in improving all microvascular variables. The superiority of MPFF over diosmin alone can be explained by the synergistic beneficial effects of the association between diosmin and active flavonoids of MPFF. Copyright © 2018 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.

Pentoxifylline for treating venous leg ulcers.

PubMed

Jull, A; Arroll, B; Parag, V; Waters, J

2007-07-18

Healing of venous leg ulcers is improved by the use of compression bandaging but some venous ulcers remain unhealed, and some people are unsuitable for compression therapy. Pentoxifylline, a drug which helps blood flow, has been used to treat venous leg ulcers. An earlier version of this review included 9 randomised controlled trials, but more research has been since been conducted and an updated review is required. To assess the effects of pentoxifylline (oxpentifylline or Trental 400) for treating venous leg ulcers, compared with placebo, or other therapies, in the presence or absence of compression therapy. For this second update we searched the Cochrane Wounds Group Specialised Register, CENTRAL, MEDLINE, EMBASE and Cinahl (date of last search was February 2007), and reference lists of relevant articles. Randomised trials comparing pentoxifylline with placebo or other therapy in the presence or absence of compression, in people with venous leg ulcers. Details from eligible trials were extracted and summarised by one author using a coding sheet. Data extraction was independently verified by one other author. Twelve trials involving 864 participants were included. The quality of trials was variable. Eleven trials compared pentoxifylline with placebo or no treatment; in seven of these trials patients received compression therapy. In one trial pentoxifylline was compared with defibrotide in patients who also received compression. Combining 11 trials that compared pentoxifylline with placebo or no treatment (with or without compression) demonstrated that pentoxifylline is more effective than placebo in terms of complete ulcer healing or significant improvement (RR 1.70, 95% CI 1.30 to 2.24). Significant heterogeneity was associated with differences in sample populations (hard-to-heal samples compared with "normal" healing samples). Pentoxifylline plus compression is more effective than placebo plus compression (RR 1.56, 95% CI 1.14 to 2.13). Pentoxifylline in the absence of compression appears to be more effective than placebo or no treatment (RR 2.25, 95% CI 1.49 to 3.39). A comparison between pentoxifylline and defibrotide found no statistically significant difference in healing rates. More adverse effects were reported in people receiving pentoxifylline (RR 1.56, 95% CI 1.10 to 2.22). Nearly three-quarters (72%) of the reported adverse effects were gastrointestinal. Pentoxifylline is an effective adjunct to compression bandaging for treating venous ulcers and may be effective in the absence of compression. The majority of adverse effects were gastrointestinal disturbances.

[Experimental study of acute brain swelling under acute intracranial hypertension (author's transl)].

PubMed

Shigemori, M; Watanabe, M; Kuramoto, S

1976-12-01

There are many problems about the cause, pathophysiology and treatment of acute brain swelling under intracranial hypertension frequently encountered in the neurosurgical clinics. Generally, rapid increase of the cerebral vasoparesis caused by unknown etiology is thought to be the main cause of acute brain swelling under intracranial hypertension. Moreover, disturbance of the cerebral venous circulatory system is discussed recently by many authors. But, research from the point of systemic respiration and hemodynamics is necessary for resolving these problems. This experiment was designed to study the effects of respiration and hemodynamics on the cerebral vasoparesis. Using 22 adult dogs, acute intracranial hypertension was produced by epidural balloon inflation sustained at the level of 300 - 400 mmH2O. Simultaneously with measurement of intracranial pressure at the epidural space, superior sagittal sinus pressure, respirogram, systemic blood pressure (femoral artery), central venous pressure, common carotid blood flow, EKG and bipolar lead EEG were monitored continuously. The experimental group was divided by the respiratory loading into 5 groups as follows: control (6 cases), 10% CO2 hypercapnia (4 cases), 10% O2 hypoxia (4 cases), stenosis of airway (5 cases), 100% O2-controled respiration (3 cases). 1) Cerebral vasoparesis under acute intracranial hypertension took place earlier and showed more rapid progression in groups of stenosis of airway, hypercapnia and hypoxia than control group of spontaneous respiration in room air. No occurrence of cerebral vasoparesis was found out in a group of 100% O2 controlled respiration. It is proved that increased airway resistance or asphyxia, hypercapnia and hypoxia have strictly reference to the occurrence and progression of cerebral vasoparesis and for the prevention of cerebral vasoparesis, correct 100% O2 cont rolled respiration is effective. 2) From the hemodynamic change, the progression of rapid increase of cerebral blood volume with increase of blood volume in the superior sagitta sinus during cerebral vasoparesis under intracranial hypertension is presumed. It is suggested from the superior sagittal sinus pressure in various experimental groups that the site, reactivity and disturbed degree of the cerebral venous system are changed by the difference of respiratory or ventrilatory state and the cerebral venous circulatory disturbance has also reference to the occurrence of acute brain swelling. 3) During cerebral vasopareris under acute intracranial hypertension, remarkable supression of respiration, increased central venous pressure and increased common carotid blood flow were observed. It is concluded that the reaction of systemic hemodynamics following respiratory change effects on cerebral circulation markedly and they are being important factors to occurrence of acute brain swelling.

Single-Session Percutaneous Endovascular Mesocaval Shunt Creation and Balloon-Occluded Retrograde Transvenous Obliteration for the Treatment of Gastric Varices.

PubMed

Srinivasa, Ravi Nara; Majdalany, Bill S; Chick, Jeffrey Forris Beecham; Meadows, J Matthew; Fenlon, Jordan Bruce; Brewerton, Charles; Saad, Wael E

2018-01-01

In the setting of portal hypertension, the body responds by creating portosystemic venous shunts, which may lead to the development of varices. Endoscopic treatment of these varices is often warranted to prevent catastrophic bleeding. During the course of variceal treatment, 1 or more portosystemic shunts may be sacrificed, which may acutely exacerbate portal hypertension and reduce systemic venous return. This report describes percutaneous creation of a mesocaval shunt and balloon-occluded retrograde transvenous obliteration (BRTO) in a patient with cavernous transformation of the portal vein. The patient had previously undergone an unsuccessful attempt at transjugular intrahepatic portosystemic shunt (TIPS) creation with postoperative bleeding requiring splenectomy. As TIPS was not feasible, creation of a percutaneous mesocaval shunt provided an alternate pathway for portosystemic decompression, facilitating safe treatment of gastric varices with BRTO via a gastrorenal shunt. These procedures were performed simultaneously to reduce the risk of variceal bleeding from acute changes in portal venous pressures and redirect blood flow through the shunt to maintain patency. This is the first reported case of combined mesocaval shunt placement and BRTO in a single session. Copyright © 2017 Elsevier Inc. All rights reserved.

Endovascular recanalization of a port catheter-associated superior vena cava syndrome.

PubMed

Tonak, Julia; Fetscher, Sebastian; Barkhausen, Jörg; Goltz, Jan Peter

2015-01-01

Superior vena cava (SVC) syndrome owing to benign etiology is rare and endovascular techniques have been advocated as the treatment of choice. We report a case of endovascular revascularization of a port catheter-associated complete occlusion of the SVC with reversed flow in the azygos vein. In this setting using a sheath in combination with its dilatator to pass the occlusion of the SVC after neither a diagnostic catheter nor a PTA balloon would pass the lesion may be a valid option. A dual venous approach was established using the right common femoral vein and an indwelling port catheter in the right cephalic vein to dilate and stent the lesion. Finally, a port may be implanted after the revascularization had been successful. Passage through the port catheter-associated occlusion of the SVC was only possible by use of the sheath in combination with its dilatator. A dual venous access by the femoral approach and the indwelling central catheter is helpful in treating a SVC occlusion. Long-term central venous catheters may cause SVC syndrome, especially with a catheter tip located too far cranially. An endovascular revascularization of a complete occlusion of the SVC represents the therapy of choice.

Diagnostic accuracy of CTA and MRI/MRA in the evaluation of the cortical venous reflux in the intracranial dural arteriovenous fistula DAVF.

PubMed

Lin, Yen-Heng; Wang, Yu-Fen; Liu, Hon-Man; Lee, Chung-Wei; Chen, Ya-Fang; Hsieh, Hong-Jen

2018-01-01

Computed tomography angiography (CTA) and magnetic resonance imaging/angiography (MRI/MRA) are used for the diagnosis of intracranial dural arteriovenous fistulas (DAVFs). The purpose of this study was to compare the diagnostic accuracy of CTA and magnetic resonance imaging/angiography (MRI/MRA) for detection of cortical venous reflux (CVR) in intracranial DAVFs. The records of patients with angiography-confirmed intracranial DAVFs who also received CTA and MRI/MRA from January 2008 to July 2016 were reviewed. CTA and MRI/MRA were reviewed for signs of CVR, and the diagnostic accuracy of individual signs was evaluated by receiver operating curve (ROC) analysis. A total 108 patients were included in this study. CTA signs of CVR included abnormal dilatation, early enhancement, and the presence of a medullary or pial vein. MRI/MRA signs of CVR included abnormal dilatation, early enhancement, flow-related enhancement, flow void, and medullary or pial venous collaterals. The sensitivity of individual CTA signs ranged from 62 to 96%, and specificities from 79 to 94%. The sensitivities of individual MRI/MRA signs ranged from 58 to 83%, and specificities from 77 to 93%. The area under ROC curve (AUC) of CTA and MRI/MRA were 0.91 and 0.87, respectively (P = 0.04 in direct comparison). In subgroup analysis, CTA had better diagnostic accuracy for higher grade disease (P = 0.05) and non-aggressive manifestation (P = 0.04). Both CTA and MRI/MRA have good diagnostic accuracy for detection of CVR in patients with intracranial DAVFs. There is modest evidence that CTA is better than MRI/MRA.

Evaluation of velocity-sensitized and acceleration-sensitized NCE-MRA for below-knee peripheral arterial disease.

PubMed

Shaida, Nadeem; Priest, Andrew N; See, T C; Winterbottom, Andrew P; Graves, Martin J; Lomas, David J

2017-06-01

To evaluate the diagnostic performance of velocity- and acceleration-sensitized noncontrast-enhanced magnetic resonance angiography (NCE-MRA) of the infrageniculate arteries using contrast-enhanced MRA (CE-MRA) as a reference standard. Twenty-four patients with symptoms of peripheral arterial disease were recruited. Each patient's infrageniculate arterial tree was examined using a velocity-dependent flow-sensitized dephasing (VEL-FSD) technique, an acceleration-dependent (ACC-FSD) technique, and our conventional CE-MRA technique performed at 1.5T. The images were independently reviewed by two experienced vascular radiologists, who evaluated each vessel segment to assess visibility, diagnostic confidence, venous contamination, and detection of pathology. In all, 432 segments were evaluated by each of the three techniques by each reader in total. Overall diagnostic confidence was rated as moderate or high in 98.5% of segments with CE-MRA, 92.1% with VEL-FSD, and 79.9% with ACC-FSD. No venous contamination was seen in 96% of segments with CE-MRA, 72.2% with VEL-FSD, and 85.8% with ACC-FSD. Per-segment, per-limb, and per-patient sensitivities for detecting significant stenotic disease were 63.4%, 73%, and 92%, respectively, for ACC-FSD, and 65.3%, 87.2%, and 96% for VEL-FSD, and as such no significant statistical change was detected using McNemar's chi-squared test with P-values of 1.00, 0.13, and 0.77 obtained, respectively. Flow-dependent NCE-MRA techniques may have a role to play in evaluation of patients with peripheral vascular disease. Increased sensitivity of a velocity-based technique compared to an acceleration-based technique comes at the expense of greater venous contamination. 2J. Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1846-1853. © 2016 International Society for Magnetic Resonance in Medicine.

Sildenafil citrate treatment enhances amino acid availability in the conceptus and fetal growth in an ovine model of intrauterine growth restriction.

PubMed

Satterfield, M Carey; Bazer, Fuller W; Spencer, Thomas E; Wu, Guoyao

2010-02-01

Adequate placental blood flow is essential for the optimal delivery of nutrients from mother to fetus for conceptus growth. Restricted fetal development results from pathophysiological and environmental factors that alter utero-placental blood flow, placental function, and, therefore, nutrient availability in the fetus. To test this hypothesis, 0, 75, or 150 mg/d sildenafil citrate (Viagra) was administered subcutaneously from d 28 to 115 of gestation to either nutrient-restricted [50% of NRC requirements) or adequately-fed ewes (100% of NRC requirements). On d 115, maternal, fetal, and placental tissues and fluids were collected. Concentrations of total amino acids and polyamines in uterine venous and arterial sera, amniotic and allantoic fluids, and fetal umbilical venous serum were lower (P < 0.05) in nutrient-restricted ewes than in adequately fed ewes, as were the ratios of total amino acids in fetal umbilical venous serum to uterine arterial serum. Sildenafil citrate dose-dependently increased (P < 0.05) total amino acids and polyamines in amniotic fluid, allantoic fluid, and fetal serum without affecting values in maternal serum. Fetal weight was lower (P < 0.05) in nutrient-restricted ewes on d 115. Sildenafil citrate treatment dose-dependently increased (P < 0.05) fetal weight in both nutrient-restricted and adequately fed ewes. This study supports the hypothesis that long-term sildenafil citrate treatment enhances fetal growth, at least in part, by increasing the availability of amino acids in the conceptus. These findings may lead to the clinical use of sildenafil citrate in human pregnancies suspected to be at risk for intrauterine fetal growth retardation.

The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

PubMed

Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

2009-07-01

Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P < 0.001). Higher PaCO2 induced an increase in mean srvO2 from 50% to 68% (P < 0.001). RvVelo (P < 0.001) and srvO2 (P = 0.007) were higher in 8 compared with 2 mm cerebral depth. RvHb was not influenced by alterations in PaCO2 but positively correlated to sevoflurane concentration (P = 0.005). Increases in rvCBF and rvVelo by PaCO2 suggest preserved hypercapnic vasodilation under anesthesia with sevoflurane 1.4% and 2.0% end-tidal concentration. A consecutive increase in srvO2 implies that cerebral arteriovenous difference in oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

Pattern of Venous Collateral Development after Splenic Vein Occlusion in an Extended Whipple Procedure (Whipple at the Splenic Artery) and Long-Term Results.

PubMed

Rosado, Ismael Dominguez; Bhalla, Sanjeev; Sanchez, Luis A; Fields, Ryan C; Hawkins, William G; Strasberg, Steven M

2017-03-01

Extended Whipple procedures may require division of the splenic vein (SV). Controversy exists regarding the risk of sequelae of sinistral portal hypertension when the SV is ligated without reimplantation. The aim of this study was to identify postoperative venous collateral patterns and sequelae of SV ligation, as well as long-term results in an extended Whipple procedure. Patients who had an extended Whipple procedure (Whipple at the Splenic Artery or WATSA) were entered in an institutional database. Evaluation of the venous collaterals was performed at least 5 months postoperatively by imaging. Spleen size and platelet counts were measured before and after operation. Fifteen patients were entered from 2009 to 2014. SV was not reconstructed and the IMV-SV junction was always resected. Two collateral routes developed. An inferior route was present 14/15 patients. It connected the residual SV to the SMV via intermediate collateral veins in the omentum and along the colon. A superior route, present in 10/15 patients connected the residual SV to the portal vein via gastric, perigastric, and coronary veins. Gastrointestinal bleeding did not occur. Mean platelet count and spleen size were not affected significantly. Procedures were long, but few severe complications developed. In 12 patients with adenocarcinoma, the median survival has not been reached. Patients who have SV ligation in an extended Whipple are protected against sequelae of sinestral portal hypertension by inferior collateral routes. The omentum and marginal veins of the colon are key links in this pathway.

Pulmonary veins in the normal lung and pulmonary hypertension due to left heart disease

PubMed Central

Hunt, James M.; Bethea, Brian; Liu, Xiang; Gandjeva, Aneta; Mammen, Pradeep P. A.; Stacher, Elvira; Gandjeva, Marina R.; Parish, Elisabeth; Perez, Mario; Smith, Lynelle; Graham, Brian B.; Kuebler, Wolfgang M.

2013-01-01

Despite the importance of pulmonary veins in normal lung physiology and the pathobiology of pulmonary hypertension with left heart disease (PH-LHD), pulmonary veins remain largely understudied. Difficult to identify histologically, lung venous endothelium or smooth muscle cells display no unique characteristic functional and structural markers that distinguish them from pulmonary arteries. To address these challenges, we undertook a search for unique molecular markers in pulmonary veins. In addition, we addressed the expression pattern of a candidate molecular marker and analyzed the structural pattern of vascular remodeling of pulmonary veins in a rodent model of PH-LHD and in lung tissue of patients with PH-LHD obtained at time of placement on a left ventricular assist device. We detected urokinase plasminogen activator receptor (uPAR) expression preferentially in normal pulmonary veins of mice, rats, and human lungs. Expression of uPAR remained elevated in pulmonary veins of rats with PH-LHD; however, we also detected induction of uPAR expression in remodeled pulmonary arteries. These findings were validated in lungs of patients with PH-LHD. In selected patients with sequential lung biopsy at the time of removal of the left ventricular assist device, we present early data suggesting improvement in pulmonary hemodynamics and venous remodeling, indicating potential regression of venous remodeling in response to assist device treatment. Our data indicate that remodeling of pulmonary veins is an integral part of PH-LHD and that pulmonary veins share some key features present in remodeled yet not normotensive pulmonary arteries. PMID:24039255

A mock circulatory system with physiological distribution of terminal resistance and compliance: application for testing the intra-aortic balloon pump.

PubMed

Kolyva, Christina; Biglino, Giovanni; Pepper, John R; Khir, Ashraf W

2012-03-01

A mock circulatory system (MCS) was designed to replicate a physiological environment for in vitro testing and was assessed with the intra-aortic balloon pump (IABP). The MCS was comprised of an artificial left ventricle (LV), connected to a 14-branch polyurethane-compound aortic model. Physiological distribution of terminal resistance and compliance according to published data was implemented with capillary tubes of different sizes and syringes of varying air volume, respectively, fitted at the outlets of the branches. The ends of the aortic branches were connected to a common tube representing the venous system and an overhead reservoir provided atrial pressure. An IABP operating a 40-cc balloon was set to counterpulsate with the LV. Total arterial compliance of the system was 0.94 mL/mm Hg and total arterial resistance was 20.3 ± 3.3 mm Hg/L/min. At control, physiological flow distribution was achieved and both mean and phasic aortic pressure and flow were physiological. With the IABP, aortic pressure exhibited the major features of counterpulsation: diastolic augmentation during inflation, inflection point at onset of deflation, and end-diastolic reduction at the end of deflation. The contribution of balloon inflation and deflation was also evident on the aortic flow pattern. This MCS was verified to be suitable for IABP testing and with further adaptations it could be used for studying other hemodynamic problems and ventricular assist devices. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Renal Hemodynamics and Ammoniagenesis

PubMed Central

Lemieux, Guy; Vinay, Patrick; Cartier, Pierre

1974-01-01

Renal production of ammonia by the left kidney was studied in 31 acidotic dogs (NH4Cl) after acute constriction of the renal artery. Renal ammoniagenesis fell in direct proportion with the reduction in glomerular filtration rate and renal plasma flow. The renal extraction of glutamine by the experimental kidney fell in direct proportion with the reduction in renal hemodynamics. Extracted glutamine remained greater than filtered glutamine indicating that both the luminal and antiluminal transport sites were operative. The relationship between renal extraction of glutamine and ammoniagenesis observed during control was maintained after renal artery constriction (1.7 μmol NH3 produced for each μmol of glutamine extracted). Systemic venous or renal intra-arterial infusion of glutamine during arterial constriction increased renal production of ammonia to or above control values. These observations indicate that the mechanisms responsible for glutamine extraction and ammonia production were operating normally despite reduced hemodynamics. When measured immediately after arterial clamping, the renal venous pNH3 was found to rise significantly decreasing progressively thereafter towards control values. The extracted fraction of total glutamine delivered to the kidney (31%) did not change after acute reduction of the glutamine load. Thus, the antiluminal extraction site was incapable of lowering renal venous plasma glutamine concentration below 0.33 μM/ml. In a second series of experiments, the properties of the antiluminal site of transport for glutamine were studied after complete occlusion of the left ureter in acidotic and nonacidotic animals. Under these circumstances, it was demonstrated that the antiluminal site is capable of extracting sufficient glutamine to maintain total ammonia production at 60% or more of control. In acidotic animals, changes in cellular pNH3 appeared to play a key role on the antiluminal extraction of glutamine since the significant rise in renal blood flow often observed after ureteral occlusion prevented the rise in pNH3 noted when blood flow remained constant. Thus, when renal blood flow rose glutamine extraction and ammonia production were maintained at control values. In these acidotic animals, glutamine infusion failed to influence ammonia production until luminal transport was restored by release of ureteral clamp and resumption of glomerular filtration. The latter observation establishes that reabsorbed glutamine is utilized at least in part for ammonia production. PMID:4812445

Impact of tubing length on hemodynamics in a simulated neonatal extracorporeal life support circuit.

PubMed

Qiu, Feng; Uluer, Mehmet C; Kunselman, Allen; Clark, J Brian; Myers, John L; Undar, Akif

2010-11-01

During extracorporeal life support (ECLS), a large portion of the hemodynamic energy is lost to various components of the circuit. Minimization of this loss in the circuit leads to better vital organ perfusion and decreases the risk of systemic inflammation. In this study, we evaluated the hemodynamic properties of differing lengths of tubing in a simulated neonatal ECLS circuit. The neonatal ECLS circuit used in this study included a Capiox Baby RX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Rotaflow centrifugal pump (MAQUET Cardiopulmonary AG, Hirrlingen, Germany), and a heater and cooler unit. An 8Fr Biomedicus arterial and a 10Fr Biomedicus venous cannula were connected to the pseudopatient. One-fourth inch tubing was used for both the arterial and the venous line. A Hoffman clamp was located upstream from the pseudopatient to maintain a certain patient pressure. Three pressure transducers were placed at different sites: postoxygenator, prearterial cannula, and postarterial cannula. The system was primed with Lactated Ringer's solution; human blood was then added to maintain a hematocrit of 40%. The volume of the pseudopatient was 500mL. We hemodynamically evaluated three circuits with different lengths of tubing: 6, 4, and 2 feet (182.88, 121.92, and 60.96 cm, respectively) for both arterial and venous lines; the priming volumes including all of the components of the circuits were 195, 155, and 115mL, respectively. In each circuit, we measured the pressure drops of the arterial tubing and the arterial cannula, as well as the flow rates at different rpm (1750-3000, 250 intervals) under three patient pressures (40, 60, and 80mm Hg). All the experiments were conducted at 37°C. The pressure drop across the arterial cannula is much larger than that of arterial tubing in all set-ups, especially under high flow rates. Upon cutting the tubing from 6 to 2 feet, the pressure drop of the arterial tubing decreased by half, while the pressure drop of the arterial cannula increased due to the slightly higher flow rates. These results suggest that compared to the arterial tubing, the arterial cannula has a larger impact on the hemodynamics of the circuit. There is a little influence of tubing length on the circuit flow rate. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

A comparison of dobutamine and levosimendan on hepatic blood flow in patients with a low cardiac output state after cardiac surgery: a randomised controlled study.

PubMed

Alvarez, J; Baluja, A; Selas, S; Otero, P; Rial, M; Veiras, S; Caruezo, V; Taboada, M; Rodriguez, I; Castroagudin, J; Tome, S; Rodriguez, A; Rodriguez, J

2013-11-01

Liver dysfunction due to a low cardiac output state after cardiac surgery is associated with a poor prognosis, but whether one inotrope is superior to another in improving hepatic perfusion remains uncertain. This study compared the systemic and hepatic haemodynamic effects of levosimendan to dobutamine in patients with a low cardiac output state (cardiac index < 2.2 l/min/m2) after on-pump cardiac surgery. A total of 25 patients were randomised to receive either an intravenous bolus of levosimendan (12 µg/kg) over 15 minutes, followed by an infusion of 0.2 µg/kg/min for 24 hours, or an infusion of dobutamine 7.5 µg/kg/min for 24 hours and completed the study. The systemic and hepatic haemodynamics at 24 and 48 hours were all better after levosimendan than dobutamine (dobutamine group: cardiac index (l/min/m2)=2.51 [standard deviation ±0.29], 2.40±0.23; portal vein flow (ml/min): 614.0±124.7, 585.9±144.8; pulsatility index: 2.02±0,28, 2.98±0.27 versus the levosimendan group: cardiac index: 3.02± 0.27, 2.98± 0.30; portal vein flow: 723.0± 143.5, 702.9±117.8; pulsatility index: 1.71±0.26, 1.73±0.27). The improvement in portal vein blood flow at 48 hours was significantly better after levosimendan than dobutamine (41% vs. 11% increment from baseline, P<0.05). In addition, there was a significant reduction in hepatic artery resistance after levosimendan but not dobutamine (resistance index reduction 6.5% vs. 0%, P<0.05). In summary, levosimendan can be considered as a selective liver vasodilator and can improve hepatic blood flow through both the hepatic artery and portal venous system, whereas dobutamine can only improve the portal venous blood flow without vasodilating the hepatic artery.

Evaluating ocular blood flow

PubMed Central

Maram, Jyotsna; Srinivas, Sowmya; Sadda, Srinivas R

2017-01-01

Studies have shown that vascular impairment plays an important role in the etiology and pathogenesis of various ocular diseases including glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal venous occlusive disease. Thus, qualitative and quantitative assessment of ocular blood flow (BF) is a topic of interest for early disease detection, diagnosis, and management. Owing to the rapid improvement in technology, there are several invasive and noninvasive techniques available for evaluating ocular BF, with each of these techniques having their own limitations and advantages. This article reviews these important techniques, with a particular focus on Doppler Fourier domain optical coherence tomography (OCT) and OCT-angiography. PMID:28573987

Blood flow and oxygen uptake during exercise

NASA Technical Reports Server (NTRS)

Mitchell, J. W.; Stolwijk, J. A. J.; Nadel, E. R.

1973-01-01

A model is developed for predicting oxygen uptake, muscle blood flow, and blood chemistry changes under exercise conditions. In this model, the working muscle mass system is analyzed. The conservation of matter principle is applied to the oxygen in a unit mass of working muscle under transient exercise conditions. This principle is used to relate the inflow of oxygen carried with the blood to the outflow carried with blood, the rate of change of oxygen stored in the muscle myoglobin, and the uptake by the muscle. Standard blood chemistry relations are incorporated to evaluate venous levels of oxygen, pH, and carbon dioxide.

Autoregulation of cerebral blood circulation under orthostatic tests

NASA Technical Reports Server (NTRS)

Gayevyy, M. D.; Maltsev, V. G.; Pogorelyy, V. E.

1980-01-01

Autoregulation of cerebral blood flow (ACBF) under orthostatic tests (OT) was estimated in acute experiments on rabbits and cats under local anesthesia according to changes of perfusion pressure (PP) in carotid arteries, cerebral blood flow, pressure in the venous system of the brain, and resistance of cerebral vessels. The OT were conducted by turning a special table with the animal fastened to it from a horizontal to a vertical (head up or head down) position at 40 to 80 deg. In most experiments ACBF correlated with the changes of PP. Different variations of ACBF and its possible mechanisms are discussed.

Agenesis of the ductus venosus-A case with favorable outcome after early signs of cardiac failure.

PubMed

Hofmann, Sigrun R; Heilmann, Antje; Häusler, Hans J; Kamin, Gabriele; Nitzsche, Katharina I

2013-01-01

Absence of the ductus venosus (ADV) is a rare vascular anomaly. Its prognosis depends on the pathway of the umbilical flow to the systemic venous circulation, and the presence or absence of associated structural or chromosomal anomalies, sometimes resulting in hydrops fetalis. In cases with isolated ADV in the absence of associated anomalies, survival rates are as high as 85%, depending on the shunt situation. Here, we report a patient with ADV and extrahepatic umbilical vein drainage with favorable outcome after intrauterine reversal of early signs of cardiac failure. Diagnosis was made after the appearance of moderate cardiomegaly in the 25th gestational week. Thus, in the case of cardiomegaly with or without further signs of cardiac failure, ultrasound imaging of the venous duct should be considered. Copyright © 2012 Wiley Periodicals, Inc.

Successful treatment of acquired uterine arterial venous malformation using N-butyl-2-cyanoacrylate under balloon occlusion

PubMed Central

Ogasawara, Go; Ishida, Kenichiro; Fujii, Kaoru; Yamane, Takuro; Nishimaki, Hiroshi; Matsunaga, Keiji; Inoue, Yusuke

2014-01-01

We present two cases of acquired uterine arterial venous malformation (AVM) which was diagnosed because of massive genital bleeding successfully treated with transcatheter arterial embolization (TAE), using N-butyl-2-cyanoacrylate (NBCA) under balloon occlusion. Balloon occlusion at the uterine artery was performed in both patients for diffuse distribution of NBCA in multiple feeding branches, as well as to the pseudoaneurysm, and for the prevention of NBCA reflux. In one of our patients, balloon occlusion of the draining vein was simultaneously performed to prevent NBCA migration through accompanying high-flow arteriovenous fistula (AVF). Doppler ultrasound at 6 months of both patients documented persistent complete occlusion of AVM. Complete and safe obliteration of acquired uterine AVM was accomplished using NBCA as embolic agent, under balloon occlusion at the communicating vessels of acquired uterine AVM. PMID:25346850

Age alters the cardiovascular response to direct passive heating

NASA Technical Reports Server (NTRS)

Minson, C. T.; Wladkowski, S. L.; Cardell, A. F.; Pawelczyk, J. A.; Kenney, W. L.

1998-01-01

During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Qc) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 +/- 1 yr) and seven older (O; 70 +/- 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Qc (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Qc was significantly lower in the older than in the young men (11.1 +/- 0.7 and 7.4 +/- 0.2 l/min in Y and O, respectively, at the limit of thermal tolerance; P < 0. 05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 +/- 7 and 68 +/- 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Qc observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 +/- 3 and 75 +/- 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 +/- 80 and 720 +/- 100 ml/min in Y and O, respectively, P < 0. 05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to the skin.

Maintenance of pulmonary vasculature tone by blood derived from the inferior vena cava in a rabbit model of cavopulmonary shunt.

PubMed

Ikai, Akio; Shirai, Mikiyasu; Nishimura, Kazunobu; Ikeda, Tadashi; Kameyama, Takayuki; Ueyama, Koji; Komeda, Masashi

2005-01-01

After cavopulmonary shunt in which the superior vena cava is anastomosed to the right pulmonary artery, the right lung is in a unique condition without flow pulsatility and hepatic venous effluent. In a previous study, we reported that hypoxic pulmonary vasoconstriction disappeared in the pulmonary circulation after cavopulmonary shunt. In this study, however, to investigate the influence of pulsatility and hepatic venous effluent on hypoxic pulmonary vasoconstriction in the pulmonary circulation, we developed an alternative cavopulmonary shunt rabbit model that included hepatic venous effluent in the pulmonary circulation and reduced the pulsatility of the pulmonary arterial blood flow. We then observed the physiologic characteristics of the peripheral pulmonary artery after cavopulmonary shunt, specifically the disappearance of hypoxic pulmonary vasoconstriction. Sixteen Japanese white rabbits (12-16 weeks old) were used in this study. With general anesthesia, a cavopulmonary shunt was established by anastomosing the right superior vena cava to the right pulmonary artery in an end-to-side fashion. Of the 16 rabbits for the study, the proximal right pulmonary artery was completely ligated in 5 (atresia group) and partially ligated in 6 (stenosis group). Sham operation was performed in the remaining 5 rabbits. Two weeks later, we analyzed the response of the pulmonary artery (which was divided into three categories: segmental, lobular, and acinar level artery) to hypoxia (8% oxygen inhalation) with a specially designed video radiographic system. Morphometric analysis of the resistance pulmonary artery was done in each group after angiography. Mean pressure and pulse pressure in the right pulmonary artery were not significantly different between the atresia and stenosis groups. The mean pulmonary artery pressures in the atresia and stenosis groups were 8 and 11 mm Hg, respectively. However, the pulse pressure was less than 2 mm Hg in both groups. The baseline internal diameter of the resistance pulmonary artery of the atresia group was significantly different from those of the stenosis and sham groups. In the atresia group, the resistance pulmonary arteries did not respond to hypoxia. In contrast, significant constriction (as assessed by percentage change of internal diameter of the resistance pulmonary arteries in the acinar and lobular level arteries) was observed in the pulmonary arteries of the sham and stenosis groups (atresia vs stenosis vs sham 0.4% vs - 19.0% vs - 18.8%, P = .01). In our morphometric study, we observed vasodilation of the resistance pulmonary artery with a thinner medial layer in the atresia group, consistent with the result of microangiography. We developed a cavopulmonary shunt rabbit model in which the inferior vena caval blood was derived from the right ventricle. Hypoxic pulmonary vasoconstriction was maintained in the model with the blood flow from the right ventricle. When the blood flow was not maintained, however, hypoxic pulmonary vasoconstriction disappeared. This phenomenon strongly suggests that a substance in hepatic venous effluent partially regulates the physiological pulmonary vascular function in the rabbit lung.

Use of PTFE Stent Grafts for Hemodialysis-related Central Venous Occlusions: Intermediate-Term Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kundu, Sanjoy, E-mail: sanjoy_kundu40@hotmail.com; Modabber, Milad; You, John M.

2011-10-15

Purpose: To assess the safety and effectiveness of a polytetrafluoroethylene (PTFE) encapsulated nitinol stents (Bard Peripheral Vascular, Tempe, AZ) for treatment of hemodialysis-related central venous occlusions. Materials and Methods: Study design was a single-center nonrandomized retrospective cohort of patients from May 2004 to August 2009 for a total of 64 months. There were 14 patients (mean age 60 years, range 50-83 years; 13 male, 1 female). All patients had autogenous fistulas. All 14 patients had central venous occlusions and presented with clinical symptoms of the following: extremity swelling (14%, 2 of 14), extremity and face swelling (72%, 10 of 14),more » and face swelling/edema (14%, 2 of 14). There was evidence of access dysfunction with decreased access flow in 36% (5 of 14) patients. There were prior interventions or previous line placement at the site of the central venous lesion in all 14 patients. Results were assessed by recurrence of clinical symptoms and function of the access circuit (National Kidney Foundation recommended criteria). Results: Sixteen consecutive straight stent grafts were implanted in 14 patients. Average treated lesion length was 5.0 cm (range, 0.9-7 cm). All 14 patients had complete central venous occlusion (100% stenosis). The central venous occlusions were located as follows: right subclavian and brachiocephalic vein (21%, 3 of 14), right brachiocephalic vein (36%, 5 of 14), left brachiocephalic vein (36%, 5 of 14), and bilateral brachiocephalic vein (7%, 1 of 14). A total of 16 PTFE stent grafts were placed. Ten- or 12-mm-diameter PTFE stent grafts were placed. The average stent length was 6.1 cm (range, 4-8 cm). Technical (deployment), anatomic (<30% residual stenosis), clinical (resolution of symptoms), and hemodynamic (resolution of access dysfunction) success were 100%. At 3, 6, and 9 months, primary patency of the treated area and access circuit were 100% (14 of 14). Conclusions: This PTFE encapsulated stent graft demonstrates encouraging intermediate-term patency results for central vein occlusions. Further prospective studies with long-term assessment and larger patient populations will be required.« less

Effects of hyperbaric oxygen on intracranial pressure and cerebral blood flow in experimental cerebral oedema1

PubMed Central

Miller, J. D.; Ledingham, I. McA.; Jennett, W. B.

1970-01-01

Increased intracranial pressure was induced in anaesthetized dogs by application of liquid nitrogen to the dura mater. Intracranial pressure and cerebral blood flow were measured, together with arterial blood pressure and arterial and cerebral venous blood gases. Carbon dioxide was administered intermittently to test the responsiveness of the cerebral circulation, and hyperbaric oxygen was delivered at intervals in a walk-in hyperbaric chamber, pressurized to two atmospheres absolute. Hyperbaric oxygen caused a 30% reduction of intracranial pressure and a 19% reduction of cerebral blood flow in the absence of changes in arterial PCO2 or blood pressure, but only as long as administration of carbon dioxide caused an increase in both intracranial pressure and cerebral blood flow. When carbon dioxide failed to influence intracranial pressure or cerebral blood flow then hyperbaric oxygen had no effect. This unresponsive state was reached at high levels of intracranial pressure. Images PMID:5497875

Internal jugular and vertebral vein volume flow in patients with clinically isolated syndrome or mild multiple sclerosis and healthy controls: results from a prospective sonographer-blinded study.

PubMed

Chambers, Brian; Chambers, Jayne; Churilov, Leonid; Cameron, Heather; Macdonell, Richard

2014-09-01

We evaluated internal jugular vein and vertebral vein volume flow using ultrasound, in patients with clinically isolated syndrome or mild multiple sclerosis and controls, to determine whether volume flow was different between the two groups. In patients and controls, internal jugular vein volume flow increased from superior to inferior segments, consistent with recruitment from collateral veins. Internal jugular vein and vertebral vein volume flow were greater on the right in supine and sitting positions. Internal jugular vein volume flow was higher in the supine posture. Vertebral vein volume flow was higher in the sitting posture. Regression analyses of cube root transformed volume flow data, adjusted for supine/sitting, right/left and internal jugular vein/vertebral vein, revealed no significant difference in volume flow in patients compared to controls. Our findings further refute the concept of venous obstruction as a causal factor in the pathogenesis of multiple sclerosis. Control volume flow data may provide useful normative reference values. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Bone tissue engineering: the role of interstitial fluid flow

NASA Technical Reports Server (NTRS)

Hillsley, M. V.; Frangos, J. A.

1994-01-01

It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

Effects of endothelium-derived nitric oxide on skin and digital blood flow in humans.

PubMed

Coffman, J D

1994-12-01

The effects of NG-monomethyl-L-arginine (L-NMMA) on total finger and forearm, and dorsal finger and forearm skin, blood flows were studied in the basal state and during reflex sympathetic vasoconstriction in normal subjects. Total flows were measured by venous occlusion plethysmography and skin flows by laser-Doppler flowmetry (LDF). L-NMMA in doses of 2, 4, and 8 microM/min given by constant infusion via a brachial artery catheter significantly decreased finger blood flow, forearm blood flow, and vascular conductances. At 8 microM/min, total finger blood flow decreased 38.4% and forearm blood flow decreased 24.8%. Dorsal finger and forearm skin LDF were also significantly decreased (25 and 37% at 8 microM/min). Body cooling significantly decreased finger blood flow (73.6%), vascular conductance, and finger LDF (59.7%). L-NMMA had no effect on total finger blood flow or dorsal finger LDF during body cooling. Nitric oxide or related compounds contribute to the basal dilator tone of the dorsal finger and forearm skin but not during reflex sympathetic vasoconstriction.

CO2 clearance by membrane lungs.

PubMed

Sun, Liqun; Kaesler, Andreas; Fernando, Piyumindri; Thompson, Alex J; Toomasian, John M; Bartlett, Robert H

2018-05-01

Commercial membrane lungs are designed to transfer a specific amount of oxygen per unit of venous blood flow. Membrane lungs are much more efficient at removing CO 2 than adding oxygen, but the range of CO 2 transfer is rarely reported. Commercial membrane lungs were studied with the goal of evaluating CO 2 removal capacity. CO 2 removal was measured in 4 commercial membrane lungs under standardized conditions. CO 2 clearance can be greater than 4 times that of oxygen at a given blood flow when the gas to blood flow ratio is elevated to 4:1 or 8:1. The CO 2 clearance was less dependent on surface area and configuration than oxygen transfer. Any ECMO system can be used for selective CO 2 removal.

Quantitative Functional Imaging Using Dynamic Positron Computed Tomography and Rapid Parameter Estimation Techniques

NASA Astrophysics Data System (ADS)

Koeppe, Robert Allen

Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations were compared to those predicted from the expired air and venous blood samples. The glucose analog ('18)F-3-deoxy-3-fluoro-D -glucose (3-FDG) was used for quantitating the membrane transport rate of glucose. The measured data indicated that the phosphorylation rate of 3-FDG was low enough to allow accurate estimation of the transport rate using a two compartment model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi Haibin, E-mail: shihb@vip.sina.com; Yang Zhengqiang; Liu Sheng

To evaluate the efficacy and safety of cyanoacrylate glue embolization in the treatment of severe arterioportal shunt (APS) presenting with hepatofugal portal venous flow in hepatocellular carcinoma (HCC) patients. Between July 2000 and January 2010, 27 HCC patients with severe APS presenting with hepatofugal portal venous flow underwent transarterial angiography and treatment. Among them, four patients were excluded from the study. Twelve patients underwent transarterial chemoperfusion and embolization of APS with cyanoacrylate glue between January 2006 and January 2010 (Emb group), and the other 11 patients undergoing only transarterial chemoperfusion without embolization of APS between July 2000 and December 2005more » served as a control group (non-Emb group). The change of APS, survival rates, and procedure related complications were analyzed. In the Emb group, APS was improved in all of the 12 patients after initial glue embolization; long-term APS improvement with hepatopetal portal flow was achieved in 80 % (8 of 10) patients who underwent follow-up angiography. Survival rates in the Emb group were 67 % at 6 months, 33 % at 1 year, and 8 % at 2 years, whereas those in the non-Emb group were 0 % at 6 months (P < 0.05). Median survival time in the Emb group was 275 days, which was longer than that of 107 days in the non-Emb group (P = 0.001). There were no major complications in both groups. The preliminary experience suggests that glue embolization may be an effective and safe therapy in the management of severe APS accompanied by HCC and also improve patient survival.« less

Hepatic function imaging using dynamic Gd-EOB-DTPA enhanced MRI and pharmacokinetic modeling.

PubMed

Ning, Jia; Yang, Zhiying; Xie, Sheng; Sun, Yongliang; Yuan, Chun; Chen, Huijun

2017-10-01

To determine whether pharmacokinetic modeling parameters with different output assumptions of dynamic contrast-enhanced MRI (DCE-MRI) using Gd-EOB-DTPA correlate with serum-based liver function tests, and compare the goodness of fit of the different output assumptions. A 6-min DCE-MRI protocol was performed in 38 patients. Four dual-input two-compartment models with different output assumptions and a published one-compartment model were used to calculate hepatic function parameters. The Akaike information criterion fitting error was used to evaluate the goodness of fit. Imaging-based hepatic function parameters were compared with blood chemistry using correlation with multiple comparison correction. The dual-input two-compartment model assuming venous flow equals arterial flow plus portal venous flow and no bile duct output better described the liver tissue enhancement with low fitting error and high correlation with blood chemistry. The relative uptake rate Kir derived from this model was found to be significantly correlated with direct bilirubin (r = -0.52, P = 0.015), prealbumin concentration (r = 0.58, P = 0.015), and prothrombin time (r = -0.51, P = 0.026). It is feasible to evaluate hepatic function by proper output assumptions. The relative uptake rate has the potential to serve as a biomarker of function. Magn Reson Med 78:1488-1495, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Modeling study on the flow patterns of gas-liquid flow for fast decarburization during the RH process

NASA Astrophysics Data System (ADS)

Li, Yi-hong; Bao, Yan-ping; Wang, Rui; Ma, Li-feng; Liu, Jian-sheng

2018-02-01

A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber: boiling pattern (BP), transition pattern (TP), and wave pattern (WP). The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.

Calculating evidence-based renal replacement therapy - Introducing an excel-based calculator to improve prescribing and delivery in renal replacement therapy - A before and after study.

PubMed

Cottle, Daniel; Mousdale, Stephen; Waqar-Uddin, Haroon; Tully, Redmond; Taylor, Benjamin

2016-02-01

Transferring the theoretical aspect of continuous renal replacement therapy to the bedside and delivering a given "dose" can be difficult. In research, the "dose" of renal replacement therapy is given as effluent flow rate in ml kg -1  h -1 . Unfortunately, most machines require other information when they are initiating therapy, including blood flow rate, pre-blood pump flow rate, dialysate flow rate, etc. This can lead to confusion, resulting in patients receiving inappropriate doses of renal replacement therapy. Our aim was to design an excel calculator which would personalise patient's treatment, deliver an effective, evidence-based dose of renal replacement therapy without large variations in practice and prolong filter life. Our calculator prescribes a haemodialfiltration dose of 25 ml kg -1  h -1 whilst limiting the filtration fraction to 15%. We compared the episodes of renal replacement therapy received by a historical group of patients, by retrieving their data stored on the haemofiltration machines, to a group where the calculator was used. In the second group, the data were gathered prospectively. The median delivered dose reduced from 41.0 ml kg -1  h -1 to 26.8 ml kg -1  h -1 with reduced variability that was significantly closer to the aim of 25 ml kg -1 .h -1 ( p  < 0.0001). The median treatment time increased from 8.5 h to 22.2 h ( p  = 0.00001). Our calculator significantly reduces variation in prescriptions of continuous veno-venous haemodiafiltration and provides an evidence-based dose. It is easy to use and provides personal care for patients whilst optimizing continuous veno-venous haemodiafiltration delivery and treatment times.

Numerical simulation of blood flow and pressure drop in the pulmonary arterial and venous circulation

PubMed Central

Qureshi, M. Umar; Vaughan, Gareth D.A.; Sainsbury, Christopher; Johnson, Martin; Peskin, Charles S.; Olufsen, Mette S.; Hill, N.A.

2014-01-01

A novel multiscale mathematical and computational model of the pulmonary circulation is presented and used to analyse both arterial and venous pressure and flow. This work is a major advance over previous studies by Olufsen and coworkers (Ottesen et al., 2003; Olufsen et al., 2012) which only considered the arterial circulation. For the first three generations of vessels within the pulmonary circulation, geometry is specified from patient-specific measurements obtained using magnetic resonance imaging (MRI). Blood flow and pressure in the larger arteries and veins are predicted using a nonlinear, cross-sectional-area-averaged system of equations for a Newtonian fluid in an elastic tube. Inflow into the main pulmonary artery is obtained from MRI measurements, while pressure entering the left atrium from the main pulmonary vein is kept constant at the normal mean value of 2 mmHg. Each terminal vessel in the network of ‘large’ arteries is connected to its corresponding terminal vein via a network of vessels representing the vascular bed of smaller arteries and veins. We develop and implement an algorithm to calculate the admittance of each vascular bed, using bifurcating structured trees and recursion. The structured-tree models take into account the geometry and material properties of the ‘smaller’ arteries and veins of radii ≥ 50µm. We study the effects on flow and pressure associated with three classes of pulmonary hypertension expressed via stiffening of larger and smaller vessels, and vascular rarefaction. The results of simulating these pathological conditions are in agreement with clinical observations, showing that the model has potential for assisting with diagnosis and treatment of circulatory diseases within the lung. PMID:24610385

Evaluation of microvascular anastomosis using real-time ultrahigh resolution Fourier domain Doppler optical coherence tomography

PubMed Central

Huang, Yong; Tong, Dedi; Zhu, Shan; Wu, Lehao; Mao, Qi; Ibrahim, Zuhaib; Lee, WP Andrew; Brandacher, Gerald; Kang, Jin U.

2014-01-01

Background Evolution and improvements in microsurgical techniques and tools have paved the way for super-microsurgical anastomoses with vessel diameters often approaching below 0.8 mm in the clinical realm and even smaller (0.2–0.3 mm) in murine models. Several imaging and monitoring devices have been introduced for post-operative monitoring but intra-operative guidance, assessment and predictability have remained limited to binocular optical microscope and surgeon’s experience. We present a high-resolution real time 3D imaging modality for intra-operative evaluation of luminal narrowing, thrombus formation and flow alterations. Methods An imaging modality that provides immediate, in-depth high resolution 3D structure view and flow information of the anastomosed site called phase resolved Doppler optical coherence tomography (PRDOCT) was developed. 22 mouse femoral artery anastomoses and 17 mouse venous anastomoses were performed and evaluated with PRDOCT. Flow status, vessel inner lumen 3D structure, and early thrombus detection were analyzed based on PRDOCT imaging results. Initial PRDOCT based predictions were correlated with actual long term surgical outcomes. Eventually four cases of mouse orthotopic limb transplantation were carried out and PRDOCT predicted long term patency were confirmed by actual results. Results PRDOCT was able to provide high-resolution 3D visualization of the vessel flow status and vessel inner lumen. The assessments based on PRDOCT visualization shows a 92% sensitivity and 90% specificity for arterial anastomoses and 90% sensitivity and 86% specificity for venous anastomoses. Conclusions PRDOCT is an effective evaluation tool for microvascular anastomosis. It can predict the long term vessel patency with high sensitivity and specificity. PMID:25811583

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

PubMed Central

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

Effects of a Preconditioning Oral Nutritional Supplement on Pig Livers after Warm Ischemia

PubMed Central

Nickkholgh, Arash; Li, Zhanqing; Yi, Xue; Mohr, Elvira; Liang, Rui; Mikalauskas, Saulius; Gross, Marie-Luise; Zorn, Markus; Benzing, Steffen; Schneider, Heinz; Büchler, Markus W.; Schemmer, Peter

2012-01-01

Background. Several approaches have been proposed to pharmacologically ameliorate hepatic ischemia/reperfusion injury (IRI). This study was designed to evaluate the effects of a preconditioning oral nutritional supplement (pONS) containing glutamine, antioxidants, and green tea extract on hepatic warm IRI in pigs. Methods. pONS (70 g per serving, Fresenius Kabi, Germany) was dissolved in 250 mL tap water and given to pigs 24, 12, and 2 hrs before warm ischemia of the liver. A fourth dose was given 3 hrs after reperfusion. Controls were given the same amount of cellulose with the same volume of water. Two hours after the third dose of pONS, both the portal vein and the hepatic artery were clamped for 40 min. 0.5, 3, 6, and 8 hrs after reperfusion, heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), portal venous flow (PVF), hepatic arterial flow (HAF), bile flow, and transaminases were measured. Liver tissue was taken 8 hrs after reperfusion for histology and immunohistochemistry. Results. HR, MAP, CVP, HAF, and PVF were comparable between the two groups. pONS significantly increased bile flow 8 hrs after reperfusion. ALT and AST were significantly lower after pONS. Histology showed significantly more severe necrosis and neutrophil infiltration in controls. pONS significantly decreased the index of immunohistochemical expression for TNF-α, MPO, and cleaved caspase-3 (P < 0.001). Conclusion. Administration of pONS before and after tissue damage protects the liver from warm IRI via mechanisms including decreasing oxidative stress, lipid peroxidation, apoptosis, and necrosis. PMID:22791934

Evaluating optimal superficial limb perfusion at different angles using non-invasive micro-lightguide spectrophotometry.

PubMed

Darmanin, Geraldine; Jaggard, Matthew; Hettiaratchy, Shehan; Nanchahal, Jagdeep; Jain, Abhilash

2013-06-01

It is common practice to elevate the limbs postoperatively to reduce oedema and hence optimise perfusion and facilitate rehabilitation. However, elevation may be counterproductive as it reduces the mean perfusion pressure. There are no clear data on the optimal position of the limbs even in normal subjects. The optimal position of limbs was investigated in 25 healthy subjects using a non-invasive micro-lightguide spectrophotometry system "O2C", which indirectly measures skin and superficial tissue perfusion through blood flow, oxygen saturation and relative haemoglobin concentration. We found a reduction in skin and superficial tissue blood flow of 17% (p=0.0001) on arm elevation (180° shoulder flexion) as compared to heart level and an increase in skin and superficial tissue blood flow of 25% (p=0.02) on forearm elevation of 45°. Lower limb skin and superficial tissue blood flow decreased by 15% (p=0.004) on elevation to 47 cm and by 70% on dependency (p=0.0001) compared to heart level. However, on elevation of the lower limb there was also a 28% reduction in superficial venous pooling (p=0.0001) compared to heart level. In the normal limb, the position for optimal superficial perfusion of the upper limb is with the arm placed at heart level and forearm at 45°. In the lower limb the optimal position for superficial perfusion would be at heart level. However, some degree of elevation may be useful if there is an element of venous congestion. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

The comparative anatomy of the forelimb veins of primates.

PubMed Central

Thiranagama, R; Chamberlain, A T; Wood, B A

1989-01-01

One hundred and thirteen forelimbs taken from 62 individuals belonging to 17 primate genera were dissected to reveal the entire course of the superficial venous system. The course of the deep venous system was also documented in at least one forelimb of each primate genus, and the number and location of perforating veins was recorded in 18 human and 45 non-human primate limbs. In Pan, Gorilla and in about 25% of human specimens the lateral superficial vein was confined to the forearm, while in all other primates, and in the majority of humans, this vein extended from the carpus to the clavicular region. Only Pongo and humans exhibited a second main superficial vein on the medial side of the forearm. In all primates the deep veins of the forelimb usually accompanied the arteries. Thus variation in the deep venous system reflected the different arterial patterns exhibited by these primates. The number of perforating veins in the forelimb was related to the length of the limb. Primate genera with longer forelimbs had more perforators, though not as many as would be expected if the number of perforators scaled linearly with limb length. PMID:2514175

Hepatic venous outflow obstruction after living donor liver transplantation managed with ectopic placement of a foley catheter: A case report

PubMed Central

Wahab, Mohamed Abdel; Shehta, Ahmed; Hamed, Hosam; Elshobary, Mohamed; Salah, Tarek; Sultan, Ahmed Mohamed; Fathy, Omar; Elghawalby, Ahmed; Yassen, Amr; Shiha, Usama

2015-01-01

Introduction The early hepatic venous outflow obstruction (HVOO) is a rare but serious complication after liver transplantation, which may result in graft loss. We report a case of early HVOO after living donor liver transplantation, which was managed by ectopic placement of foley catheter. Presentation A 51 years old male patient with end stage liver disease received a right hemi-liver graft. On the first postoperative day the patient developed impairment of the liver functions. Doppler ultrasound (US) showed absence of blood flow in the right hepatic vein without thrombosis. The decision was to re-explore the patient, which showed torsion of the graft upward and to the right side causing HVOO. This was managed by ectopic placement of a foley catheter between the graft and the diaphragm and the chest wall. Gradual deflation of the catheter was gradually done guided by Doppler US and the patient was discharged without complications. Discussion Mechanical HVOO results from kinking or twisting of the venous anastomosis due to anatomical mismatch between the graft and the recipient abdomen. It should be managed surgically by repositioning of the graft or redo of venous anastomosis. Several ideas had been suggested for repositioning and fixation of the graft by the use of Sengstaken–Blakemore tubes, tissue expanders, and surgical glove expander. Conclusion We report the use of foley catheter to temporary fix the graft and correct the HVOO. It is a simple and safe way, and could be easily monitored and removed under Doppler US without any complications. PMID:25805611

Automatic Control of Veno-Venous Extracorporeal Lung Assist.

PubMed

Kopp, Ruedger; Bensberg, Ralf; Stollenwerk, Andre; Arens, Jutta; Grottke, Oliver; Walter, Marian; Rossaint, Rolf

2016-10-01

Veno-venous extracorporeal lung assist (ECLA) can provide sufficient gas exchange even in most severe cases of acute respiratory distress syndrome. Commercially available systems are manually controlled, although an automatically controlled ECLA could allow individualized and continuous adaption to clinical requirements. Therefore, we developed a demonstrator with an integrated control algorithm to keep continuously measured peripheral oxygen saturation and partial pressure of carbon dioxide constant by automatically adjusting extracorporeal blood and gas flow. The "SmartECLA" system was tested in six animal experiments with increasing pulmonary hypoventilation and hypoxic inspiratory gas mixture to simulate progressive acute respiratory failure. During a cumulative evaluation time of 32 h for all experiments, automatic ECLA control resulted in a peripheral oxygen saturation ≥90% for 98% of the time with the lowest value of 82% for 15 s. Partial pressure of venous carbon dioxide was between 40 and 49 mm Hg for 97% of the time with no value <35 mm Hg or >49 mm Hg. With decreasing inspiratory oxygen concentration, extracorporeal oxygen uptake increased from 68 ± 25 to 154 ± 34 mL/min (P < 0.05), and reducing respiratory rate resulted in increasing extracorporeal carbon dioxide elimination from 71 ± 37 to 92 ± 37 mL/min (P < 0.05). The "SmartECLA" demonstrator allowed reliable automatic control of the extracorporeal circuit. Proof of concept could be demonstrated for this novel automatically controlled veno-venous ECLA circuit. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Spatial distribution of venous gas emboli in the lungs

NASA Technical Reports Server (NTRS)

Souders, J. E.; Doshier, J. B.; Polissar, N. L.; Hlastala, M. P.

1999-01-01

The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-microm fluorescent microspheres at baseline and during N(2) embolism. The animals were killed, and the lungs were excised, air-dried, and diced into approximately 2-cm(3) pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 +/- 1% per additional centimeter in height compared with baseline (P = 0.0003). Embolism also increased radially by 3 +/- 1%/cm from the hilum (P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 +/- 2% for every 1. 0 increase in relative baseline flow (P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature.

Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps

NASA Astrophysics Data System (ADS)

Polzin, A.-E.; Kabelac, S.; de Vries, B.

2016-09-01

Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.