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Sample records for severe hemodynamic alteration

  1. Congenital heart malformations induced by hemodynamic altering surgical interventions

    PubMed Central

    Midgett, Madeline; Rugonyi, Sandra

    2014-01-01

    Embryonic heart formation results from a dynamic interplay between genetic and environmental factors. Blood flow during early embryonic stages plays a critical role in heart development, as interactions between flow and cardiac tissues generate biomechanical forces that modulate cardiac growth and remodeling. Normal hemodynamic conditions are essential for proper cardiac development, while altered blood flow induced by surgical manipulations in animal models result in heart defects similar to those seen in humans with congenital heart disease. This review compares the altered hemodynamics, changes in tissue properties, and cardiac defects reported after common surgical interventions that alter hemodynamics in the early chick embryo, and shows that interventions produce a wide spectrum of cardiac defects. Vitelline vein ligation and left atrial ligation decrease blood pressure and flow; and outflow tract banding increases blood pressure and flow velocities. These three surgical interventions result in many of the same cardiac defects, which indicate that the altered hemodynamics interfere with common looping, septation and valve formation processes that occur after intervention and that shape the four-chambered heart. While many similar defects develop after the interventions, the varying degrees of hemodynamic load alteration among the three interventions also result in varying incidence and severity of cardiac defects, indicating that the hemodynamic modulation of cardiac developmental processes is strongly dependent on hemodynamic load. PMID:25136319

  2. Hemodynamic alterations in chronically conscious unrestrained diabetic rats

    SciTech Connect

    Carbonell, L.F.; Salmon, M.G.; Garcia-Estan, J.; Salazar, F.J.; Ubeda, M.; Quesada, T.

    1987-05-01

    Important cardiovascular dysfunctions have been described in streptozotocin (STZ)-diabetic rats. To determine the influence of these changes on the hemodynamic state and whether insulin treatment can avoid them, different hemodynamic parameters, obtained by the thermodilution method, were studied in STZ-induced (65 mg/kg) diabetic male Wistar rats, as well as in age-control, weight-control, and insulin-treated diabetic ones. Plasma volume was measured by dilution of radioiodinated (/sup 125/I) human serum albumin. All rats were examined in the conscious, unrestrained state 12 wk after induction of diabetes or acidified saline (pH 4.5) injection. At 12 wk of diabetic state most important findings were normotension, high blood volume, bradycardia, increase in stroke volume, cardiac output, and cardiosomatic ratio, and decrease in total peripheral resistance and cardiac contractility and relaxation (dP/dt/sub max/ and dP/dt/sub min/ of left ventricular pressure curves). The insulin-treated diabetic rats did not show any hemodynamic differences when compared with the control animals. These results suggest that important hemodynamic alterations are present in the chronic diabetic states, possibly conditioning congestive heart failure. These alterations can be prevented by insulin treatment.

  3. Computational Hemodynamic Simulation of Human Circulatory System under Altered Gravity

    NASA Technical Reports Server (NTRS)

    Kim. Chang Sung; Kiris, Cetin; Kwak, Dochan

    2003-01-01

    A computational hemodynamics approach is presented to simulate the blood flow through the human circulatory system under altered gravity conditions. Numerical techniques relevant to hemodynamics issues are introduced to non-Newtonian modeling for flow characteristics governed by red blood cells, distensible wall motion due to the heart pulse, and capillary bed modeling for outflow boundary conditions. Gravitational body force terms are added to the Navier-Stokes equations to study the effects of gravity on internal flows. Six-type gravity benchmark problems are originally presented to provide the fundamental understanding of gravitational effects on the human circulatory system. For code validation, computed results are compared with steady and unsteady experimental data for non-Newtonian flows in a carotid bifurcation model and a curved circular tube, respectively. This computational approach is then applied to the blood circulation in the human brain as a target problem. A three-dimensional, idealized Circle of Willis configuration is developed with minor arteries truncated based on anatomical data. Demonstrated is not only the mechanism of the collateral circulation but also the effects of gravity on the distensible wall motion and resultant flow patterns.

  4. Dietary melatonin alters uterine artery hemodynamics in pregnant Holstein heifers.

    PubMed

    Brockus, K E; Hart, C G; Gilfeather, C L; Fleming, B O; Lemley, C O

    2016-04-01

    The objective was to examine uterine artery hemodynamics and maternal serum profiles in pregnant heifers supplemented with dietary melatonin (MEL) or no supplementation (CON). In addition, melatonin receptor-mediated responses in steroid metabolism were examined using a bovine endometrial epithelial culture system. Twenty singleton pregnant Holstein heifers were supplemented with 20 mg of melatonin (n = 10) or no melatonin supplementation (control; n = 10) from days 190 to 262 of gestation. Maternal measurements were recorded on days 180 (baseline), 210, 240, and 262 of gestation. Total uterine blood flow was increased by 25% in the MEL-treated heifers compared with the CON. Concentrations of progesterone were decreased in MEL vs CON heifers. Total serum antioxidant capacity was increased by 43% in MEL-treated heifers when compared with CON. Activity of cytochrome P450 1A, 2C, and superoxide dismutase was increased in bovine endometrial epithelial cells treated with melatonin, whereas the melatonin receptor antagonist, luzindole, negated the increase in cytochrome P450 2C activity. Moreover, estradiol or progesterone treatment altered bovine uterine melatonin receptor expression, which could potentiate the melatonin-mediated responses during late gestation. The observed increase in total uterine blood flow during melatonin supplementation could be related to its antioxidant properties. Compromised pregnancies are typically accompanied by increased oxidative stress; therefore, melatonin could serve as a therapeutic supplementation strategy. This could lead to further fetal programming implications in conjunction with offspring growth and development postnatally. PMID:26641925

  5. Dietary melatonin alters uterine artery hemodynamics in pregnant holstein heifers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to examine uterine artery hemodynamics and maternal serum profiles in pregnant heifers supplemented with dietary melatonin (MEL) or no supplementation (CON). In addition, melatonin receptor–mediated responses in steroid metabolism were examined using a bovine endometrial epithelial...

  6. Altering hemodynamics leads to congenital heart defects (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ford, Stephanie M.; McPheeters, Matthew T.; Wang, Yves T.; Gu, Shi; Doughman, Yong Qiu; Strainic, James P.; Rollins, Andrew M.; Watanabe, Michiko; Jenkins, Michael W.

    2016-03-01

    The role of hemodynamics in early heart development is poorly understood. In order to successfully assess the impact of hemodynamics on development, we need to monitor and perturb blood flow, and quantify the resultant effects on morphology. Here, we have utilized cardiac optical pacing to create regurgitant flow in embryonic hearts and OCT to quantify regurgitation percentage and resultant morphology. Embryonic quail in a shell-less culture were optically paced at 3 Hz (well above the intrinsic rate or 1.33-1.67 Hz) on day 2 of development (3-4 weeks human) for 5 minutes. The pacing fatigued the heart and led to a prolonged period (> 1 hour) of increased regurgitant flow. Embryos were kept alive until day 3 (cardiac looping - 4-5 weeks human) or day 8 (4 chambered heart - 8 weeks human) to quantify resultant morphologic changes with OCT. All paced embryos imaged at day 3 displayed cardiac defects. The extent of regurgitant flow immediately after pacing was correlated with cardiac cushion size 24-hours post pacing (p-value < 0.01) with higher regurgitation leading to smaller cushions. Almost all embryos (16/18) surviving to day 8 exhibited congenital heart defects (CHDs) including 11/18 with valve defects, 5/18 with ventricular septal defects and 5/18 with hypoplastic right ventricles. Our data suggests that regurgitant flow leads to smaller cushions, which develop into abnormal valves and septa. Our model produces similar phenotypes as found in our fetal alcohol syndrome and velo-cardio-facial/DiGeorge syndrome models suggesting that hemodynamics plays a role in these syndromes as well. Utilizing OCT and optical pacing to understand hemodynamics in development is an important step towards determining CHD mechanisms and ultimately developing earlier treatments.

  7. Hemodynamics.

    PubMed

    Secomb, Timothy W

    2016-04-01

    A review is presented of the physical principles governing the distribution of blood flow and blood pressure in the vascular system. The main factors involved are the pulsatile driving pressure generated by the heart, the flow characteristics of blood, and the geometric structure and mechanical properties of the vessels. The relationship between driving pressure and flow in a given vessel can be understood by considering the viscous and inertial forces acting on the blood. Depending on the vessel diameter and other physical parameters, a wide variety of flow phenomena can occur. In large arteries, the propagation of the pressure pulse depends on the elastic properties of the artery walls. In the microcirculation, the fact that blood is a suspension of cells strongly influences its flow properties and leads to a nonuniform distribution of hematocrit among microvessels. The forces acting on vessel walls include shear stress resulting from blood flow and circumferential stress resulting from blood pressure. Biological responses to these forces are important in the control of blood flow and the structural remodeling of vessels, and also play a role in major disease processes including hypertension and atherosclerosis. Consideration of hemodynamics is essential for a comprehensive understanding of the functioning of the circulatory system. PMID:27065172

  8. Vascular tracers alter hemodynamics and airway pressure in anesthetized sheep

    SciTech Connect

    Albertine, K.H.; Staub, N.C.

    1986-11-01

    The technique of vascular labeling was developed to mark sites of increased microvascular permeability. We used the vascular labeling technique in anesthetized sheep and found that hemodynamics and airway pressure were adversely affected by intraarterial infusions of two vascular tracers. Monastral blue (nine sheep) immediately caused systemic arterial hypotension, pulmonary arterial hypertension, and bronchoconstriction. All three physiological responses were partially blocked by a cyclooxygenase inhibitor (indomethacin) but not by an H1-antihistamine (chlorpheniramine). Colloidal gold (nine sheep) caused immediate, but less dramatic, pulmonary arterial hypertension which was not attenuated by the blocking agents. We conclude that these two vascular tracers caused detrimental physiological side effects in sheep at the usual doses used to label injured microvessels in other species.

  9. Persistent vascular collagen accumulation alters hemodynamic recovery from chronic hypoxia

    PubMed Central

    Tabima, Diana M.; Roldan-Alzate, Alejandro; Wang, Zhijie; Hacker, Timothy A.; Molthen, Robert C.; Chesler, Naomi C.

    2011-01-01

    Pulmonary arterial hypertension (PAH) is caused by narrowing and stiffening of the pulmonary arteries that increase pulmonary vascular impedance (PVZ). In particular, small arteries narrow and large arteries stiffen. Large pulmonary artery (PA) stiffness is the best current predictor of mortality from PAH. We have previously shown that collagen accumulation leads to extralobar PA stiffening at high strain (Ooi, Wang et al. 2010). We hypothesized that collagen accumulation would increase PVZ, including total pulmonary vascular resistance (Z0), characteristic impedance (ZC), pulse wave velocity (PWV), and index of global wave reflections (Pb/Pf), which contribute to increased right ventricular afterload. We tested this hypothesis by exposing mice unable to degrade type I collagen (Col1a1R/R) to 21 days of hypoxia (hypoxia), some of which were allowed to recover for 42 days (recovery). Littermate wild-type mice (Col1a1+/+) were used as controls. In response to hypoxia, mean PA pressure (mPAP) increased in both mouse genotypes with no changes in cardiac output (CO) or PA inner diameter (ID); as a consequence, Z0 (mPAP/CO) increased by ~100% in both genotypes (p<0.05). Contrary to our expectations, ZC, PWV and Pb/Pf did not change. However, with recovery, ZC and PWV decreased in the Col1a1+/+ mice and remained unchanged in the Col1a1R/R mice. Z0 decreased with recovery in both genotypes. Microcomputed tomography measurements of large PAs did not show evidence of stiffness changes as a function of hypoxia exposure or genotype. We conclude that hypoxia-induced PA collagen accumulation does not affect the pulsatile components of pulmonary hemodynamics but that excessive collagen accumulation does prevent normal hemodynamic recovery, which may have important consequences for right ventricular function. PMID:22183202

  10. A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System.

    PubMed

    Menon, Vinal; Junor, Lorain; Balhaj, Marwa; Eberth, John F; Potts, Jay D

    2016-01-01

    The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and molecular level. To alter intracardiac hemodynamics, fertilized chicken eggs are incubated in a humidified chamber to obtain embryos of the desired stage (HH17). Once this developmental stage is achieved, the embryo is maintained ex ovo and hemodynamics in the embryonic heart are altered by partially constricting the outflow tract (OFT) with a surgical suture at the junction of the OFT and ventricle (OVJ). Control embryos are also cultured ex ovo but are not subjected to the surgical intervention. Banded and control embryos are then incubated in a humidified incubator for the desired period of time, after which 2D ultrasound is employed to analyze the change in blood flow velocity at the OVJ as a result of OFT banding. Once embryos are maintained ex ovo, it is important to ensure adequate hydration in the incubation chamber so as to prevent drying and eventually embryo death. Using this new banded model, it is now possible to perform analyses of changes in the expression of key players involved in valve development and to understand the role of hemodynamics on cellular responses in vivo, which could not be achieved previously. PMID:27213265

  11. Premedication with oral dexmedetomidine alters hemodynamic actions of intravenous anesthetic agents in chronically instrumented dogs.

    PubMed

    Proctor, L T; Schmeling, W T; Warltier, D C

    1992-09-01

    Dexmedetomidine (the D-stereoisomer of medetomidine), a highly selective alpha 2-adrenoceptor agonist, has been demonstrated to produce analgesia and sedation and attenuate hemodynamic responses to emergence from inhalational anesthetics, which suggests a potential use for this drug as a premedicant for general anesthesia. The authors examined hemodynamic interactions between dexmedetomidine and three commonly used intravenous anesthetic agents with markedly different hemodynamic effects. Conscious, chronically instrumented dogs received intravenous induction doses of ketamine, propofol, or etomidate, followed by continuous infusions of each drug at four different doses for 15-min intervals on different days. Studies in six separate groups (range, 9-12 dogs/group) with and without pretreatment with oral dexmedetomidine (20 micrograms/kg) were completed. Heart rate, arterial pressure, left ventricular pressure, rate of increase of left ventricular pressure at 50 mmHg (dP/dt50), and cardiac output were continuously recorded. Dexmedetomidine administration caused a significant (P less than 0.05) decrease in heart rate, rate-pressure product, left ventricular dP/dt50, and cardiac output. Dexmedetomidine abolished or attenuated the increase in heart rate, rate-pressure product, cardiac output, and arterial pressure produced during induction of anesthesia with ketamine. After the dexmedetomidine pretreatment, continuous infusion of ketamine caused no increase in heart rate or rate-pressure product. However, ketamine significantly reduced left ventricular dP/dt50 compared to control in dogs premedicated with dexmedetomidine. Except for a significant reduction in systemic vascular resistance, dexmedetomidine did not significantly affect the hemodynamic response to induction of anesthesia with propofol. Similarly, dexmedetomidine did little to alter the hemodynamic response to induction of anesthesia with etomidate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1355639

  12. Hemodynamic Response Alteration As a Function of Task Complexity and Expertise-An fNIRS Study in Jugglers.

    PubMed

    Carius, Daniel; Andrä, Christian; Clauß, Martina; Ragert, Patrick; Bunk, Michael; Mehnert, Jan

    2016-01-01

    Detailed knowledge about online brain processing during the execution of complex motor tasks with a high motion range still remains elusive. The aim of the present study was to investigate the hemodynamic responses within sensorimotor networks as well as in visual motion area during the execution of a complex visuomotor task such as juggling. More specifically, we were interested in how far the hemodynamic response as measured with functional near infrared spectroscopy (fNIRS) adapts as a function of task complexity and the level of the juggling expertise. We asked expert jugglers to perform different juggling tasks with different levels of complexity such as a 2-ball juggling, 3- and 5-ball juggling cascades. We here demonstrate that expert jugglers show an altered neurovascular response with increasing task complexity, since a 5-ball juggling cascade showed enhanced hemodynamic responses for oxygenated hemoglobin as compared to less complex tasks such as a 3- or 2-ball juggling pattern. Moreover, correlations between the hemodynamic response and the level of the juggling expertise during the 5-ball juggling cascade, acquired by cinematographic video analysis, revealed only a non-significant trend in primary motor cortex, indicating that a higher level of expertise might be associated with lower hemodynamic responses. PMID:27064925

  13. Hemodynamic Response Alteration As a Function of Task Complexity and Expertise—An fNIRS Study in Jugglers

    PubMed Central

    Carius, Daniel; Andrä, Christian; Clauß, Martina; Ragert, Patrick; Bunk, Michael; Mehnert, Jan

    2016-01-01

    Detailed knowledge about online brain processing during the execution of complex motor tasks with a high motion range still remains elusive. The aim of the present study was to investigate the hemodynamic responses within sensorimotor networks as well as in visual motion area during the execution of a complex visuomotor task such as juggling. More specifically, we were interested in how far the hemodynamic response as measured with functional near infrared spectroscopy (fNIRS) adapts as a function of task complexity and the level of the juggling expertise. We asked expert jugglers to perform different juggling tasks with different levels of complexity such as a 2-ball juggling, 3- and 5-ball juggling cascades. We here demonstrate that expert jugglers show an altered neurovascular response with increasing task complexity, since a 5-ball juggling cascade showed enhanced hemodynamic responses for oxygenated hemoglobin as compared to less complex tasks such as a 3- or 2-ball juggling pattern. Moreover, correlations between the hemodynamic response and the level of the juggling expertise during the 5-ball juggling cascade, acquired by cinematographic video analysis, revealed only a non-significant trend in primary motor cortex, indicating that a higher level of expertise might be associated with lower hemodynamic responses. PMID:27064925

  14. A theoretical analysis of hemodynamic and biomechanical alterations in intracranial AVMs after radiosurgery

    SciTech Connect

    Lo, E.H. )

    1993-09-20

    Stereotactic radiosurgery is being increasingly used to treat intracranial arteriovenous malformations (AVMs). However, successful radiosurgery may involve latent periods of 1-2 years prior to AVM obliteration. This latent period include states of altered flow patterns that may not influence hemorrhage probabilities. The probability of hemorrhage is likely to be related to the degree of biomechanical stress across the AVM shunt walls. This paper describes a theoretical analysis of the altered hemodynamics and biomechanical stresses within AVM shunts post-radiosurgery. The mathematical model is comprised of linked flow compartments that represent the AVM and adjacent normal vasculature. As obliteration of the irradiated shunts occurs, changes in flow rates and pressure gradients are calculated based on first order fluid dynamics. Stress on the AVM shunt walls is calculated based on tangential forces due to intramural pressure. Two basic models are presented: a distribution of shunts with fixed thin walls subject to step-function obliteration, and a distribution of shunts subject to luminal obliteration from slowly thickening walls. Variations on these models are analyzed, including sequential, selective and random shunt obliteration, and uniform or Poisson distributions of shunt radii. Model I reveals that the range of pressure alterations in the radiosurgically-treated AVM include the possibility of transient increases in the total biomechanical stress within the shunt walls prior to obliteration. Model II demonstrates that uniform luminal narrowing via thickened walls should lead to reduced transmural stresses. The precise temporal pattern of AVM flow decrease and biomechanical stress reduction depends on the selection of shunts that are obliterated. 34 refs., 5 figs., 1 tab.

  15. Pathogenic alteration in severe burn wounds.

    PubMed

    Fu, Yang; Xie, Bing; Ben, DaoFeng; Lv, KaiYang; Zhu, ShiHui; Lu, Wei; Tang, HongTai; Cheng, DaSheng; Ma, Bing; Wang, GuangYi; Xiao, ShiChu; Wang, GuangQing; Xia, ZhaoFan

    2012-02-01

    The present study aims to define the trend of time related changes with local bacterial alteration of bacterial resistance in severe burns in our burn center during a 12-year period. Retrospective analysis of microbiological results on severely burned wounds between 1998 and 2009 was carried out. A study of 3615 microbial isolates was performed. Staphylococcus aureus was the most commonly isolated pathogen (38.2%) followed by A. baumannii (16.2%), Streptococcus viridans (11.4%), Pseudomonas aeruginosa (10.4%), coagulase-negative staphylococci (CNS, 9.2%). The species ratios of S. aureus and A. baumannii increased significantly from 1st to 8th week of hospitalization, while those of Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci decreased during the same period. Bacterial resistance rates were compared between the periods 1998-2003 and 2004-2009. Vancomycin remained as the most sensitive antibiotic in S. aureus including methicillin-resistant S. aureus (MRSA). It was very likely that the majority of infections caused by Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci occurred in the early stage of burn course and the majority of infections caused by A. baumannii occurred 4 weeks after admission. The use of different antibiotics was probably the major contributor to these trends. PMID:22100426

  16. Altered Hemodynamic Activity in Conduct Disorder: A Resting-State fMRI Investigation

    PubMed Central

    Zhou, Jiansong; Yao, Nailin; Fairchild, Graeme; Zhang, Yingdong; Wang, Xiaoping

    2015-01-01

    Background Youth with conduct disorder (CD) not only inflict serious physical and psychological harm on others, but are also at greatly increased risk of sustaining injuries, developing depression or substance abuse, and engaging in criminal behaviors. The underlying neurobiological basis of CD remains unclear. Objective The present study investigated whether participants with CD have altered hemodynamic activity under resting-state conditions. Methods Eighteen medication-naïve boys with CD and 18 age- and sex- matched typically developing (TD) controls underwent functional magnetic resonance imaging (MRI) scans in the resting state. The amplitude of low-frequency fluctuations (ALFF) was measured and compared between the CD and TD groups. Results Compared with the TD participants, the CD participants showed lower ALFF in the bilateral amygdala/parahippocampus, right lingual gyrus, left cuneus and right insula. Higher ALFF was observed in the right fusiform gyrus and right thalamus in the CD participants compared to the TD group. Conclusions Youth with CD displayed widespread functional abnormalities in emotion-related and visual cortical regions in the resting state. These results suggest that deficits in the intrinsic activity of resting state networks may contribute to the etiology of CD. PMID:25816069

  17. Cerebral Hemodynamics and Vascular Reactivity in Mild and Severe Ischemic Rodent Middle Cerebral Artery Occlusion Stroke Models

    PubMed Central

    Sim, Jeongeun; Jo, Areum; Kang, Bok-Man; Lee, Sohee; Bang, Oh Young; Heo, Chaejeong; Jhon, Gil-Ja; Lee, Youngmi

    2016-01-01

    Ischemia can cause decreased cerebral neurovascular coupling, leading to a failure in the autoregulation of cerebral blood flow. This study aims to investigate the effect of varying degrees of ischemia on cerebral hemodynamic reactivity using in vivo real-time optical imaging. We utilized direct cortical stimulation to elicit hyper-excitable neuronal activation, which leads to induced hemodynamic changes in both the normal and middle cerebral artery occlusion (MCAO) ischemic stroke groups. Hemodynamic measurements from optical imaging accurately predict the severity of occlusion in mild and severe MCAO animals. There is neither an increase in cerebral blood volume nor in vessel reactivity in the ipsilateral hemisphere (I.H) of animals with severe MCAO. The pial artery in the contralateral hemisphere (C.H) of the severe MCAO group reacted more slowly than both hemispheres in the normal and mild MCAO groups. In addition, the arterial reactivity of the I.H in the mild MCAO animals was faster than the normal animals. Furthermore, artery reactivity is tightly correlated with histological and behavioral results in the MCAO ischemic group. Thus, in vivo optical imaging may offer a simple and useful tool to assess the degree of ischemia and to understand how cerebral hemodynamics and vascular reactivity are affected by ischemia. PMID:27358581

  18. Hemodynamic Alterations after Stent Implantation in 15 Cases of Intracranial Aneurysms

    PubMed Central

    Wang, Chao; Tian, Zhongbin; Liu, Jian; Jing, Linkai; Paliwal, Nikhil; Wang, Shengzhang; Zhang, Ying; Xiang, Jianping; Siddiqui, Adnan H; Meng, Hui; Yang, Xinjian

    2016-01-01

    Background Stent-assisted coiling technology has been widely used in the treatment of intracranial aneurysms. In current study, we investigated the intra-aneurysmal hemodynamic alterations after stent implantation and its association with aneurysm location. Methods We first retrospectively studied 15 aneurysm cases (8 internal carotid artery-ophthalmic artery (ICA-OphA) aneurysms and 7 posterior communicating artery (PcoA) aneurysms) treated with Enterprise stents and coils. Then based on patient-specific geometries before and after stenting, we built virtual stenting computational fluid dynamics (CFD) simulation models. Results Before and after stent deployment, the average Wall Shear Stress (WSS) on the aneurysmal sac at systolic peak changed from 7.04 Pa (4.14 Pa, 15.77 Pa) to 6.04 Pa (3.86 Pa, 11.13 Pa), P = 0.001; and the spatially averaged value of flow velocity in the perpendicular plane of aneurysm dropped from 0.5 m/s (0.28 m/s, 0.7 m/s) to 0.33 m/s (0.25 m/s, 0.49 m/s), P = 0.001, respectively. Post-stent implantation, WSS in ICA-OphA aneurysms and PcoA aneurysms decreased by 14.4% (P = 0.012) and 16.6% (P = 0.018) respectively, and flow velocity also reduced by 10.3% (P = 0.029) and 10.5% (P = 0.013), respectively. Changes in WSS, flow velocity, and pressure were not significantly different between ICA-OphA aneurysms and PcoA aneurysms (P > 0.05). Stent implantation did not significantly change the peak systolic pressure in both aneurysm types. Conclusion After stent implantation, intra-aneurysmal flow velocity and WSS decreased independent of aneurysm type (ICA-OphA and PcoA). Little change was observed on peak systolic pressure. PMID:26746828

  19. Iliac arteriovenous fistula due to spinal disk surgery. Causes severe hemodynamic repercussion with pulmonary hypertension.

    PubMed Central

    Machado-Atías, I; Fornés, O; González-Bello, R; Machado-Hernández, I

    1993-01-01

    We present a case of a 46-year-old man with a pulsatile mass in the left inferior abdominal quadrant that irradiated a continuous murmur extending to the left lumbar region. Despite an 8-year history of cardiomegaly, he appeared to be asymptomatic except for the mass and could recollect no traumatic injury or surgery that might have caused it. Near the vertebral column, we found a small scar, the result of spinal disk surgery 11 years before. Following chest radiography and electrocardiography, we located the suspected arteriovenous fistula by selective angiography of the aorta and its branches: a communication of the left iliac artery with the left iliac vein had resulted in a very large left-to-right shunt and a severely dilated inferior vena cava. We then divided and isolated the arterial segment containing the fistula, but left this segment in continuity with the left iliac vein by over-sewing both ends. To avoid injury to surrounding structures, dissection was limited to the area of maximal thrill. Hemodynamic improvement was immediate, and the postoperative course was uneventful. At the present time, almost 3 years postoperatively, the patient is asymptomatic. Images PMID:8508067

  20. Study of severe scorpion envenoming following subcutaneous venom injection into dogs: Hemodynamic and concentration/effect analysis.

    PubMed

    Elatrous, Souheil; Ouanes-Besbes, Lamia; Ben Sik-Ali, Habiba; Hamouda, Zineb; BenAbdallah, Saoussen; Tilouche, Nejla; Jalloul, Faten; Fkih-Hassen, Mohamed; Dachraoui, Fahmi; Ouanes, Islem; Abroug, Fekri

    2015-09-15

    To evaluate the dose-effects of Androctonus australis hector (Aah) venom injected subcutaneously on hemodynamics and neurohormonal secretions, 10 anesthetized and ventilated mongrel dogs, were split in two groups (n = 5/group). Subcutaneous injection was done with either 0.2 mg/kg or 0.125 mg/kg of the purified G50 scorpion toxic fraction. Hemodynamic parameters using right heart catheter were recorded and plasma concentrations of catecholamine, troponin, and serum toxic fraction were measured sequentially from baseline to 120 min. We identified the dose of toxic fraction evoking characteristic hemodynamic perturbation of severe envenomation, the time-lapse to envenomation, and the associated plasma level. The injection of 0.125 mg/kg toxic fraction was not associated with significant variations in hemodynamic parameters, whereas the 0.2 mg/kg dose caused envenomation characterized by significant increase in plasma catecholamines, increased pulmonary artery occluded pressure, mean arterial pressure, and systemic vascular resistance (p < 0.05), in association with sustained decline in cardiac output (p < 0.001). Envenomation occurred by the 30th minute, and the corresponding concentration of toxic fraction was 1.14 ng/ml. The current experiment allowed the identification of the sub-lethal dose (0.2 mg/kg) of the toxic fraction of Aah administered by the subcutaneous route. Two parameters with potential clinical relevance were also uncovered: the time-lapse to envenomation and the corresponding concentration of toxic fraction. PMID:26166304

  1. A NO way to BOLD? Dietary nitrate alters the hemodynamic response to visual stimulation.

    PubMed

    Aamand, Rasmus; Dalsgaard, Thomas; Ho, Yi-Ching Lynn; Møller, Arne; Roepstorff, Andreas; Lund, Torben E

    2013-12-01

    Neurovascular coupling links neuronal activity to vasodilation. Nitric oxide (NO) is a potent vasodilator, and in neurovascular coupling NO production from NO synthases plays an important role. However, another pathway for NO production also exists, namely the nitrate-nitrite-NO pathway. On this basis, we hypothesized that dietary nitrate (NO3-) could influence the brain's hemodynamic response to neuronal stimulation. In the present study, 20 healthy male participants were given either sodium nitrate (NaNO3) or sodium chloride (NaCl) (saline placebo) in a crossover study and were shown visual stimuli based on the retinotopic characteristics of the visual cortex. Our primary measure of the hemodynamic response was the blood oxygenation level dependent (BOLD) response measured with high-resolution functional magnetic resonance imaging (0.64×0.64×1.8 mm) in the visual cortex. From this response, we made a direct estimate of key parameters characterizing the shape of the BOLD response (i.e. lag and amplitude). During elevated nitrate intake, corresponding to the nitrate content of a large plate of salad, both the hemodynamic lag and the BOLD amplitude decreased significantly (7.0±2% and 7.9±4%, respectively), and the variation across activated voxels of both measures decreased (12.3±4% and 15.3±7%, respectively). The baseline cerebral blood flow was not affected by nitrate. Our experiments demonstrate, for the first time, that dietary nitrate may modulate the local cerebral hemodynamic response to stimuli. A faster and smaller BOLD response, with less variation across local cortex, is consistent with an enhanced hemodynamic coupling during elevated nitrate intake. These findings suggest that dietary patterns, via the nitrate-nitrite-NO pathway, may be a potential way to affect key properties of neurovascular coupling. This could have major clinical implications, which remain to be explored. PMID:23827330

  2. Alteration of Intra-Aneurysmal Hemodynamics for Flow Diversion Using Enterprise and Vision Stents

    PubMed Central

    Tremmel, Markus; Xiang, Jianping; Natarajan, Sabareesh K.; Hopkins, L. Nelson; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui

    2010-01-01

    Objective Flow diversion is a novel concept for intracranial aneurysm treatment. The recently developed Enterprise Vascular Reconstruction Device (Codman Neurovascular, Raynham MA) provides easy delivery and repositioning. Although designed specifically for restraining coils within an aneurysm, this stent has theoretical effects on modifying flow dynamics, which have not been studied. The goal of this study was to quantify the effect of single and multiple self-expanding Enterprise stents alone or in combination with balloon-mounted stents on aneurysm hemodynamics using computational fluid dynamics (CFD). Methods The geometry of a wide-necked, saccular, basilar trunk aneurysm was reconstructed from computed tomographic angiography images. Various combinations of 1–3 stents were “virtually” conformed to fit into the vessel lumen and placed across the aneurysm orifice. CFD analysis was performed to calculate hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each model. Results The complex aneurysmal flow pattern was suppressed by stenting. Stent placement lowered average flow velocity in the aneurysm; further reduction was achieved by additional stent deployment. Aneurysmal flow turnover time, an indicator of stasis, was increased to 114-117% for single-stent, 127-128% for double-stent, and 141% for triple-stent deployment. Furthermore, aneurysmal wall shear stress (WSS) decreased with increasing number of deployed stents. Conclusion This is the first study analyzing flow modifications associated with placement of Enterprise stents for aneurysm occlusion. Placement of 2-3 stents significantly reduced intra-aneurysmal hemodynamic activities, thereby increasing the likelihood of inducing aneurysm thrombotic occlusion. PMID:21197155

  3. Alteration of podocyte protein expression and localization in the early stage of various hemodynamic conditions.

    PubMed

    Li, Kai; Wang, Juan; Yin, Xiaohui; Zhai, Xiaoyue; Li, Zilong

    2013-01-01

    Given that podocalyxin (PCX) and nestin play important roles in podocyte morphogenesis and the maintenance of structural integrity, we examined whether the expression and localization of these two podocyte proteins were influenced in the early stage of various hemodynamic conditions. Mice kidney tissues were prepared by in vivo cryotechnique (IVCT). The distribution of glomeruli and podocyte proteins was visualized with DAB staining, confocal laser scanning microscopy and immunoelectron microscopy. The mRNA levels were examined by real-time quantitative PCR. The results showed the following: Under the normal condition, PCX stained intensely along glomerular epithelial cells, whereas nestin was clearly staining in the endothelial cells and appeared only weakly in the podocytes. Under the acute hypertensive and cardiac arrest conditions, PCX and nestin staining was not clear, with a disarranged distribution, but the colocalization of PCX and nestin was apparent under this condition. In addition, under the acute hypertensive and cardiac arrest conditions, the mRNA levels of PCX and nestin were significantly decreased. Collectively, the abnormal redistribution and decreased mRNA expressions of PCX and nestin are important molecular events at the early stage of podocyte injury during hemodynamic disorders. IVCT may have more advantages for morphological analysis when researching renal diseases. PMID:23502465

  4. Impact of altered venous hemodynamic conditions on the formation of platelet layers in thromboemboli.

    PubMed

    Bajd, Franci; Vidmar, Jernej; Fabjan, Andrej; Blinc, Aleš; Kralj, Eduard; Bizjak, Nina; Serša, Igor

    2012-02-01

    Although it is generally believed that the structure of venous thromboemboli is a homogeneous red blood cell-fibrin clot, their structure may be heterogeneous, with non-uniformly distributed platelet layers, known as the lines of Zahn. We tested (a) whether venous thromboemboli ex vivo contained platelet layers, i.e. the lines of Zahn, and (b) whether, according to mathematical modeling, eddies can arise in the venous system, possibly contributing to platelet aggregation. The structure of venous thromboemboli ex vivo was determined by high-resolution magnetic resonance imaging (MRI) and by immunohistochemistry (IHC). High-resolution ultrasound (US) imaging was employed to determine the popliteal vein geometry and hemodynamics in healthy subjects and in subjects with previous venous thrombosis. The US data were then used as input for numerical simulations of venous hemodynamics. MRI and IHC confirmed that 42 of 49 ex vivo venous thromboemboli were structurally heterogeneous with platelet layers. The peak venous flow velocity was higher in patients with partly recanalized deep vein thrombosis than in healthy subjects in the prone position (46±4cm/s vs. 16±3cm/s). Our numerical simulation showed that partial venous obstruction with stenosis or malfunctioning venous valves creates the conditions for eddy blood flow. Our experimental results and computer simulation confirmed that the heterogeneous structure of venous thromboemboli with twisted platelet layers may be associated with eddy flow at the sites of their formation. PMID:21962985

  5. Altered Resting-State Cortical EEG Oscillations in Patients With Severe Asymptomatic Carotid Stenosis.

    PubMed

    Hsiao, Fu-Jung; Hsieh, Fang-Yuh; Chen, Wei-Ta; Chu, Da-Chen; Lin, Yung-Yang

    2016-04-01

    Asymptomatic carotid stenosis is characterized by altered cerebral hemodynamics and cognitive impairment, but the underlying neurophysiological mechanism remains unclear. To elucidate the alterations of cortical activities, resting-state electrophysiological activities were recorded from patients with mild (<30%; n=10; age 57-85 years), moderate (30% to 50%; n=11; age 66-88 years), and severe (>50%; n=8; age 67-91 years) carotid stenosis. The current density and oscillatory power of the cortical sources were analyzed using the minimum norm estimates method combined with fast Fourier transform analysis. Our results indicate that the cortical current density among regions of the brain was similar, irrespective of the degree of carotid stenosis. With regard to the cortical oscillations, augmented theta activities in the bilateral parietal, left temporal, and left occipital regions and attenuated alpha activities in the bilateral frontal and right central regions were obtained in patients with severe asymptomatic carotid stenosis. We suggest that the source-based cortical oscillations at theta and alpha bands might reflect the alterations of the brain activities and characterize the altered neurophysiological mechanism of the brain with at least 50% occlusion of the carotid artery. Further longitudinal studies with larger populations are warranted to verify the present findings. PMID:25465434

  6. [Anesthetic Induction in a Patient with Giant Ovarian Tumor Who Developed Severe Hemodynamic Instability].

    PubMed

    Aoi, Ryota; Ishihara, Mariko; Soh, Mirei; Kohno, Michihiko; Soga, Mayumi; Kohata, Hisakazu; Takahashi, Kan

    2015-08-01

    A 45 year-old woman underwent a laparotomy for a giant ovarian tumor under general anesthesia. Preoperative CT scan revealed a 30 cm-diameter tumor compressing IVC. She had slight respiratory discomfort on supine position, but respiratory function test showed no abnormalities. In the operating room, after oxygenation for 3 minutes, general anesthesia was induced with fentanyl 100 μg, propofol 90 mg and rocuronium 40 mg on supine position. Immediately after the induction, her systolic blood pressure and heart rate fell to 45 mmHg and 40 beats per minute, respectively. We considered that her hemodynamic instability was supine hypotensive syndrome due to giant ovarian tumor. Therefore we placed her 30 degree right side up and pushed her tumor to the left so as not to compress the IVC. We rapidly injected acetated Ringer's solution 500 ml, ephedrine 12 mg and phenylephrine 0.1 mg, and her hemodynamic status soon recovered to normal ranges. The anesthetic induction of a patient with a giant ovarian tumor is challenging. Some reports recommend strategies such as induction on lateral position or suctioning tumor contents before induction. Careful induction of general anesthesia is required for these patients. PMID:26442415

  7. Glomerular hemodynamic alterations during acute hyperinsulinemia in normal and diabetic rats

    NASA Technical Reports Server (NTRS)

    Tucker, B. J.; Anderson, C. M.; Thies, R. S.; Collins, R. C.; Blantz, R. C.

    1992-01-01

    Treatment of insulin dependent diabetes invariably requires exogenous insulin to control blood glucose. Insulin treatment, independent of other factors associated with insulin dependent diabetes, may induce changes that affect glomerular function. Due to exogenous delivery of insulin in insulin dependent diabetes entering systemic circulation prior to the portal vein, plasma levels of insulin are often in excess of that observed in non-diabetics. The specific effects of hyperinsulinemia on glomerular hemodynamics have not been previously examined. Micropuncture studies were performed in control (non-diabetic), untreated diabetic and insulin-treated diabetic rats 7 to 10 days after administration of 65 mg/kg body weight streptozotocin. After the first period micropuncture measurements were obtained, 5 U of regular insulin (Humulin-R) was infused i.v., and glucose clamped at euglycemic values (80 to 120 mg/dl). Blood glucose concentration in non-diabetic controls was 99 +/- 6 mg/dl. In control rats, insulin infusion and glucose clamp increased nephron filtration rate due to decreases in both afferent and efferent arteriolar resistance (afferent greater than efferent) resulting in increased plasma flow and increased glomerular hydrostatic pressure gradient. However, insulin infusion and glucose clamp produced the opposite effect in both untreated and insulin-treated diabetic rats with afferent arteriolar vasoconstriction resulting in decreases in plasma flow, glomerular hydrostatic pressure gradient and nephron filtration rate. Thromboxane A2 (TX) synthetase inhibition partially decreased the vasoconstrictive response due to acute insulin infusion in diabetic rats preventing the decrease in nephron filtration rate.(ABSTRACT TRUNCATED AT 250 WORDS).

  8. Alterations in uterine hemodynamics caused by uterine fibroids and their impact on in vitro fertilization outcomes

    PubMed Central

    Moon, Jei-Won; Kim, Jun-Bum; Kim, Sung-Hoon; Chae, Hee-Dong; Kang, Byung-Moon

    2015-01-01

    Objective To investigate the impact of fibroids on the blood flow of the uterine and subendometrial arteries and in vitro fertilization (IVF) outcomes. Methods In this study, we analyzed 86 IVF/intracytoplasmic sperm injection (ICSI) cycles in which a gonadotropin-releasing hormone antagonist protocol was used for controlled ovarian stimulation between January 2008 and March 2009. The subjects comprised 86 infertile women with (fibroid group, n=43) or without (control group, n=43) uterine fibroids. Results Patient characteristics were similar between the fibroid and control groups. The IVF/ICSI outcomes in patients with fibroids were similar to those of patients in the control group. The resistance index (RI) and pulsatile index (PI) of the uterine and subendometrial arteries on the day of embryo transfer were also comparable between the two groups. IVF outcomes and uterine hemodynamics in patients with multiple (≥2) fibroids were similar to those of patients with a single fibroid. However, clinical pregnancy and implantation rates were significantly lower in patients with fibroids who experienced uterine cavity distortion than in patients with fibroids who had a normal uterine cavity (both p<0.05). The RI and PI of the subendometrial artery were significantly higher on the day of embryo transfer in patients with fibroids who experienced uterine cavity distortion than in patients with fibroids who had a normal uterine cavity (both p<0.05). Conclusion Fibroids which distorting the uterine cavity might impair the subendometrial artery blood flow clinical pregnancy rate and embryo implantation rate in infertile patients undergoing IVF. Otherwise, IVF outcomes were not influenced by the presence of uterine fibroids. PMID:26816875

  9. Hemodynamic and metabolic basis of impaired exercise tolerance in patients with severe left ventricular dysfunction

    SciTech Connect

    Roubin, G.S.; Anderson, S.D.; Shen, W.F.; Choong, C.Y.; Alwyn, M.; Hillery, S.; Harris, P.J.; Kelly, D.T. )

    1990-04-01

    Hemodynamic and metabolic changes were measured at rest and during exercise in 23 patients with chronic heart failure and in 6 control subjects. Exercise was limited by leg fatigue in both groups and capacity was 40% lower in the patients with failure. At rest, comparing patients with control subjects, heart rate and right atrial and pulmonary wedge pressure were higher; cardiac output, stroke volume and work indexes and ejection fraction were lower; mean arterial and right atrial pressure and systemic resistance were similar. During all phases of exercise in patients with heart failure, pulmonary wedge pressure and systemic vascular resistance were higher and pulmonary vascular resistance remained markedly elevated compared with values in control subjects. Cardiac output was lower in the patients with failure, but appeared to have the same physiologic distribution in both groups during exercise. Although arterial-femoral venous oxygen content difference was higher in patients with heart failure, this increase did not compensate for the reduced blood flow. Even though the maximal oxygen consumption was significantly reduced, femoral venous lactate and pH values were higher than values in control subjects, but femoral venous pH was similar in both groups at their respective levels of maximal exercise. Ejection fraction was lower in those with heart failure at rest and did not increase with exercise. Ventilation in relation to oxygen consumption was higher in patients with failure than in control subjects.

  10. Alterations in hemodynamics and Kf,c during lung mass resection.

    PubMed

    Townsley, M I; Parker, J C; Korthuis, R J; Taylor, A E

    1987-12-01

    The effects of progressive lung mass reduction on total pulmonary vascular resistance (RT), compliance (CT), arterial (Pa), venous (PV), and capillary (Pc) pressures, and the capillary filtration coefficient (Kf,c) were evaluated in whole isolated dog lungs perfused with autologous blood. RT increased (P less than 0.05) in a nonlinear fashion when mass was reduced by greater than 35% in zone 3 lungs (Pa greater than PV greater than airway pressure) perfused at constant pressure (CP, n = 9), a finding predicted by a model of rigid parallel flow channels subjected to loss of cross-sectional area. Furthermore, these findings were not altered by pretreatment with ibuprofen or diphenhydramine (n = 7). In contrast, in zone 3 lungs perfused with constant flow (CF, n = 4), RT did not increase until at least 60-75% of mass was removed. Since Pa and Pc were constant in the former group, but increased in the latter group (P less than 0.05), the attenuation of RT by CF is best explained by vascular distension. This is supported by the finding that microvascular C, as a fraction of CT, decreased significantly with CF, but not with CP. Kf,c and CT (referenced to the initial lung mass) decreased linearly with reductions in lung mass % delta Kf,c = 1.26-0.98% mass removed (r = 0.90, P less than 0.01) and % delta CT = -3.99-0.98% mass removed (r = 0.82, P less than 0.01) relationships that were not altered by blocker pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3436877

  11. Hemodynamic evaluation of suspected severe aortic stenosis leads to a diagnosis of renal cell carcinoma.

    PubMed

    Lake, Mikhailia; Tanawuttiwat, Tanyanan; Bilsker, Martin; De Marchena, Eduardo

    2015-02-01

    The evaluation of aortic stenosis is not always straightforward. When symptoms of severe aortic stenosis are present with supporting Doppler echocardiographic or cardiac catheterization data, replacement of the aortic valve is recommended. Occasionally, Doppler- and catheter-derived data are discordant; appropriate treatment in such cases becomes less clear. We report a case in which a 66-year-old man's symptoms and Doppler data suggested severe aortic stenosis. However, heart catheterization data suggested otherwise, and ultimately it led to the diagnosis of a highly vascular renal tumor. Shunting within the tumor resulted in high cardiac output, which, in combination with a small aortic root, masqueraded as severe aortic stenosis. PMID:25873807

  12. Computational representation and hemodynamic characterization of in vivo acquired severe stenotic renal artery geometries using turbulence modeling.

    PubMed

    Kagadis, George C; Skouras, Eugene D; Bourantas, George C; Paraskeva, Christakis A; Katsanos, Konstantinos; Karnabatidis, Dimitris; Nikiforidis, George C

    2008-06-01

    The present study reports on computational fluid dynamics in the case of severe renal artery stenosis (RAS). An anatomically realistic model of a renal artery was reconstructed from CT scans, and used to conduct CFD simulations of blood flow across RAS. The recently developed shear stress transport (SST) turbulence model was pivotally applied in the simulation of blood flow in the region of interest. Blood flow was studied in vivo under the presence of RAS and subsequently in simulated cases before the development of RAS, and after endovascular stent implantation. The pressure gradients in the RAS case were many orders of magnitude larger than in the healthy case. The presence of RAS increased flow resistance, which led to considerably lower blood flow rates. A simulated stent in place of the RAS decreased the flow resistance at levels proportional to, and even lower than, the simulated healthy case without the RAS. The wall shear stresses, differential pressure profiles, and net forces exerted on the surface of the atherosclerotic plaque at peak pulse were shown to be of relevant high distinctiveness, so as to be considered potential indicators of hemodynamically significant RAS. PMID:17714975

  13. Awake cardiopulmonary bypass to prevent hemodynamic collapse and loss of airway in a severely symptomatic patient with a mediastinal mass.

    PubMed

    Said, Sameh M; Telesz, Brian J; Makdisi, George; Quevedo, Fernando J; Suri, Rakesh M; Allen, Mark S; Mauermann, William J

    2014-10-01

    Management of a large mediastinal mass causing respiratory and hemodynamic compromise represents a major challenge during induction of anesthesia and surgical resection. The hemodynamic changes associated with anesthetic induction and initiation of positive-pressure ventilation can lead to acute hemodynamic collapse or inability to ventilate, or both. Initiation of cardiopulmonary bypass before anesthetic induction represents a safe alternative. We present a 37-year-old woman who underwent successful resection of a large anterior mediastinal mass through sternotomy. Cardiopulmonary bypass was instituted using the right femoral vessels under local analgesia to allow safe anesthetic induction. Her postoperative course was uneventful. This represents an example of a team approach to the management of a complex patient to achieve a successful outcome. PMID:25282247

  14. Causal connectivity alterations of cortical-subcortical circuit anchored on reduced hemodynamic response brain regions in first-episode drug-naïve major depressive disorder

    PubMed Central

    Gao, Qing; Zou, Ke; He, Zongling; Sun, Xueli; Chen, Huafu

    2016-01-01

    Some efforts were done to investigate the disruption of brain causal connectivity networks involved in major depressive disorder (MDD) using Granger causality (GC) analysis. However, the homogenous hemodynamic response function (HRF) assumption over the brain may disturb the inference of temporal precedence. Here we applied a blind deconvolution approach to examine the altered HRF shape in first-episode, drug-naïve MDD patients. The regions with abnormal HRF shape in patients were chosen as seeds to detect the GC alterations in MDD. The results demonstrated significantly decreased magnitude of spontaneous hemodynamic response of the orbital frontal cortex (OFC) and the caudate nucleus (CAU) in MDD comparing to healthy controls, suggesting MDD patients likely had alterations in neurovascular coupling and cerebrovascular physiology in these two regions. GC mapping showed increased/decreased GC in OFC-/CAU centered networks in MDD. The outgoing GC values from OFC to anterior cingulate cortex and occipital regions were positively correlated with Hamilton Depression Scale (HAMD) scores, while the incoming GC from insula, middle and superior temporal gyrus to CAU were negatively correlated with HAMD scores of MDD. The abnormalities of directional connections in the cortico-subcortico-cerebellar network may lead to unbalanced integrating the emotional-related information for MDD, and further exacerbating depressive symptoms. PMID:26911651

  15. Causal connectivity alterations of cortical-subcortical circuit anchored on reduced hemodynamic response brain regions in first-episode drug-naïve major depressive disorder.

    PubMed

    Gao, Qing; Zou, Ke; He, Zongling; Sun, Xueli; Chen, Huafu

    2016-01-01

    Some efforts were done to investigate the disruption of brain causal connectivity networks involved in major depressive disorder (MDD) using Granger causality (GC) analysis. However, the homogenous hemodynamic response function (HRF) assumption over the brain may disturb the inference of temporal precedence. Here we applied a blind deconvolution approach to examine the altered HRF shape in first-episode, drug-naïve MDD patients. The regions with abnormal HRF shape in patients were chosen as seeds to detect the GC alterations in MDD. The results demonstrated significantly decreased magnitude of spontaneous hemodynamic response of the orbital frontal cortex (OFC) and the caudate nucleus (CAU) in MDD comparing to healthy controls, suggesting MDD patients likely had alterations in neurovascular coupling and cerebrovascular physiology in these two regions. GC mapping showed increased/decreased GC in OFC-/CAU centered networks in MDD. The outgoing GC values from OFC to anterior cingulate cortex and occipital regions were positively correlated with Hamilton Depression Scale (HAMD) scores, while the incoming GC from insula, middle and superior temporal gyrus to CAU were negatively correlated with HAMD scores of MDD. The abnormalities of directional connections in the cortico-subcortico-cerebellar network may lead to unbalanced integrating the emotional-related information for MDD, and further exacerbating depressive symptoms. PMID:26911651

  16. Hyperoxia causes oxygen free radical-mediated membrane injury and alters myocardial function and hemodynamics in the newborn.

    PubMed

    Bandali, K S; Belanger, M P; Wittnich, C

    2004-08-01

    Newborn children can be exposed to high oxygen levels (hyperoxia) for hours to days during their medical and/or surgical management, and they also can have poor myocardial function and hemodynamics. Whether hyperoxia alone can compromise myocardial function and hemodynamics in the newborn and whether this is associated with oxygen free radical release that overwhelms naturally occurring antioxidant enzymes leading to myocardial membrane injury was the focus of this study. Yorkshire piglets were anesthetized with pentobarbital sodium (65 mg/kg), intubated, and ventilated to normoxia. Once normal blood gases were confirmed, animals were randomly allocated to either 5 h of normoxia [arterial Po(2) (Pa(O(2))) = 83 +/- 5 mmHg, n = 4] or hyperoxia (Pa(O(2)) = 422 +/- 33 mmHg, n = 6), and myocardial functional and hemodynamic assessments were made hourly. Left ventricular (LV) biopsies were taken for measurements of antioxidant enzyme activities [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] and malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) as an indicator of oxygen free radical-mediated membrane injury. Hyperoxic piglets suffered significant reductions in contractility (P < 0.05), systolic blood pressure (P < 0.03), and mean arterial blood pressure (P < 0.05). Significant increases were seen in heart rate (P < 0.05), whereas a significant 11% (P < 0.05) and 61% (P < 0.001) reduction was seen in LV SOD and GPx activities, respectively, after 5 h of hyperoxia. Finally, MDA and 4-HNE levels were significantly elevated by 45% and 38% (P < 0.001 and P = 0.02), respectively, in piglets exposed to hyperoxia. Thus, in the newborn, hyperoxia triggers oxygen free radical-mediated membrane injury together with an inability of the newborn heart to upregulate its antioxidant enzyme defenses while impairing myocardial function and hemodynamics. PMID:15277198

  17. Hemodynamic variables and progression of acute kidney injury in critically ill patients with severe sepsis: data from the prospective observational FINNAKI study

    PubMed Central

    2013-01-01

    Introduction Knowledge of the association of hemodynamics with progression of septic acute kidney injury (AKI) is limited. However, some recent data suggest that mean arterial pressure (MAP) exceeding current guidelines (60–65 mmHg) may be needed to prevent AKI. We hypothesized that higher MAP during the first 24 hours in the intensive care unit (ICU), would be associated with a lower risk of progression of AKI in patients with severe sepsis. Methods We identified 423 patients with severe sepsis and electronically recorded continuous hemodynamic data in the prospective observational FINNAKI study. The primary endpoint was progression of AKI within the first 5 days of ICU admission defined as new onset or worsening of AKI by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We evaluated the association of hemodynamic variables with this endpoint. We included 53724 10-minute medians of MAP in the analysis. We analysed the ability of time-adjusted MAP to predict progression of AKI by receiver operating characteristic (ROC) analysis. Results Of 423 patients, 153 (36.2%) had progression of AKI. Patients with progression of AKI had significantly lower time-adjusted MAP, 74.4 mmHg [68.3-80.8], than those without progression, 78.6 mmHg [72.9-85.4], P < 0.001. A cut-off value of 73 mmHg for time-adjusted MAP best predicted the progression of AKI. Chronic kidney disease, higher lactate, higher dose of furosemide, use of dobutamine and time-adjusted MAP below 73 mmHg were independent predictors of progression of AKI. Conclusions The findings of this large prospective multicenter observational study suggest that hypotensive episodes (MAP under 73 mmHg) are associated with progression of AKI in critically ill patients with severe sepsis. PMID:24330815

  18. Effects of Phosphodiesterase Type 5 Inhibition on Systemic and Pulmonary Hemodynamics and Ventricular Function in Patients with Severe Symptomatic Aortic Stenosis

    PubMed Central

    Lindman, Brian R.; Zajarias, Alan; Madrazo, José A.; Shah, Jay; Gage, Brian F.; Novak, Eric; Johnson, Stephanie N.; Chakinala, Murali M.; Hohn, Tara A.; Saghir, Mohammed; Mann, Douglas L.

    2012-01-01

    Background Pressure overload due to aortic stenosis (AS) causes maladaptive ventricular and vascular remodeling that can lead to pulmonary hypertension, heart failure symptoms, and adverse outcomes. Retarding or reversing this maladaptive remodeling and its unfavorable hemodynamic consequences has potential to improve morbidity and mortality. Preclinical models of pressure overload have shown that phosphodiesterase type 5 (PDE5) inhibition is beneficial, however the use of PDE5 inhibitors in patients with AS is controversial because of concerns about vasodilation and hypotension. Methods and Results We evaluated the safety and hemodynamic response of 20 subjects with severe symptomatic AS (mean aortic valve area 0.7±0.2 cm2, ejection fraction 60±14%) who received a single oral dose of sildenafil (40mg or 80mg). Compared to baseline, after 60 minutes sildenafil reduced systemic (−12%, p<0.001) and pulmonary (−29%, p=0.002) vascular resistance, mean pulmonary artery (−25%, p<0.001) and wedge (−17%, p<0.001) pressure, and increased systemic (+13%, p<0.001) and pulmonary (+45%, p<0.001) vascular compliance and stroke volume index (+8%, p=0.01). These changes were not dose dependent. Sildenafil caused a modest decrease in mean systemic arterial pressure (−11%, p<0.001), but was well-tolerated with no episodes of symptomatic hypotension. Conclusions This study shows for the first time that a single dose of a PDE5 inhibitor is safe and well-tolerated in patients with severe AS and is associated with acute improvements in pulmonary and systemic hemodynamics resulting in biventricular unloading. These findings support the need for longer-term studies to evaluate the role of PDE5 inhibition as adjunctive medical therapy in patients with AS. PMID:22447809

  19. Hemodynamic and clinical response to three-day infusion of sulmazol (AR-L 115 BS) in severe congestive heart failure.

    PubMed

    Renard, M; Jacobs, P; Dechamps, P; Dresse, A; Bernard, R

    1983-10-01

    Sulmazol (AR-L 115 BS) is a new positively inotropic drug with arterial and venous vasodilating properties. We studied the effects of sulmazol (three-day infusion) on clinical tolerance, hemodynamics, and blood gas levels in ten patients with severe chronic heart failure. The hemodynamic monitoring included a Swan-Ganz catheter in the pulmonary artery and a radial catheter. Blood gas levels were determined on samples of arterial and mixed venous blood. After 24 hours of infusion, there was a significant increase in cardiac index (2 to 2.5 L/min/sq m; p less than 0.005) and a significant decrease in pulmonary wedge pressure (28 to 19 mm Hg; p less than 0.001) and in right atrial pressure (7 to 4 mm Hg; p less than 0.001) without significant changes in heart rate and systolic blood pressure. These beneficial effects lasted during the three days of infusion. Oxygen delivery was significantly increased (350 to 443 ml/min/sq m; p less than 0.005) without significant change in arterial oxygen tension. The side effects included nausea, vomiting, anorexia, and mild thrombocytopenia. We conclude that sulmazol is a potent drug which may improve severely deteriorated left and right ventricular function in patients with chronic refractory heart failure without affecting the heart rate and the systolic blood pressure. PMID:6413136

  20. [Cerebral hemodynamics in children of 8-12 years old with alterations of the motor activity of central origin].

    PubMed

    Holovchenko, I V; Haĭdaĭ, M I

    2013-01-01

    In children with altered physical activity there is a lack of brain blood supply, which is the most pronounced in the system of the vertebral arteries right hemisphere, and a low volume speed of blood flow in the internal carotid artery and in the system of the vertebral arteries. Children of the main group have a decreased venous outflow from the cavity of the skull, which is accompanied by altered venous circulation in the sinuses of the brain. It is established that in the system of the vertebral arteries a hemispheric asymmetry of growth in the right hemisphere is observed, in contrast to the left hemisphere, indicators of vascular tone of arterial and venous type of small caliber. Children with altered physical activity have higher values of indicators of venous outflow, than the children of the control group, and they have better venous outflow from the carotid system and a slightly worse with vertebro-basilar. PMID:24400562

  1. Angiotensin inhibition in severe heart failure: acute central and limb hemodynamic effects of captopril with observations on sustained oral therapy.

    PubMed

    Faxon, D P; Halperin, J L; Creager, M A; Gavras, H; Schick, E C; Ryan, T J

    1981-05-01

    The systemic, pulmonary, and limb circulatory responses to the angiotensin-converting enzyme inhibitor, captopril, were determined in 10 patients with severe, chronic heart failure. Immediate effects include sustained reductions in arterial pressure and pulmonary capillary wedge pressure and improvement in cardiac output, as reported with other vasodilator drugs. Calf vascular resistance did not change despite substantial lowering of total systemic vascular resistance, indicating that arteriolar dilatation occurred on a selective basis. Transient reduction in mean right atrial pressure paralleled slight calf venodilatation, but effects upon the resistance vasculature predominated. Plasma renin activity and norepinephrine concentrations increased after therapy in the acute phase as plasma aldosterone levels consistently fell. During maintenance oral treatment over 7 to 15 months (median, 11.5 months), patients displayed symptomatic benefit, improved functional capacity, and greater exercise tolerance. No major adverse reactions developed. These findings suggest that angiotensin converting enzyme inhibition with captopril in congestive heart failure patients improved cardiocirculatory function through selective arteriolar dilatation. The reordering of regional blood flow which appears to result from release of angiotensin-mediated vasoconstriction, as well as the suppression of aldosterone, may underlie the prolonged benefit observed in these patients. This oral vasodilator appears to represent an effective adjunct for the treatment of advanced, chronic heart failure refractory to conventional measures. PMID:7013458

  2. Effects of Moderate-to-Severe Impairment of the Estimated Glomerular Filtration Rate and of Proteinuria on the Central Hemodynamics and Arterial Stiffness in Middle-Aged Healthy Japanese Men

    PubMed Central

    Tomiyama, Hirofumi; Odaira, Mari; Matsumoto, Chisa; Yamada, Jiko; Yoshida, Masanobu; Shiina, Kazuki; Yamashina, Akira

    2011-01-01

    We evaluated the effects of moderate-to-severe impairment of the estimated glomerular filtration rate (eGFR: 15 to 59 mL/min per 1.73 m2) and of proteinuria on the central hemodynamics and the pulse wave velocity (PWV) in 2244 middle-aged healthy Japanese men who were not receiving any medications for cardiovascular diseases or cardiovascular risk factors. The adjusted value of the radial augmentation index was higher in the subjects with proteinuria than in those without proteinuria. On the other hand, this value was similar between the subjects with and without moderate-to-severe impairment of the eGFR. Not only proteinuria but also moderate-to-severe impairment of the eGFR was associated with increase in the adjusted value of the brachial-ankle PWV. Thus, proteinuria was found to be an independent risk factor for abnormal central hemodynamics and increased stiffness of the large- to middle-sized arteries, while moderate-to-severe impairment of the eGFR was associated with an increase of the arterial stiffness, but not with abnormality of the central hemodynamics. PMID:21423551

  3. Correlations of Flow Structure and Particle Deposition with Structural Alterations in Severe Asthmatic Lungs

    NASA Astrophysics Data System (ADS)

    Choi, Sanghun; Miyawaki, Shinjiro; Choi, Jiwoong; Hoffman, Eric A.; Wenzel, Sally; Lin, Ching-Long

    2014-11-01

    Severe asthmatics are characterized by alterations of bifurcation angle, hydraulic diameter, circularity of the airways, and local shift of air-volume functional change. The characteristics altered against healthy human subjects can affect flow structure and particle deposition. A large-eddy-simulation (LES) model for transitional and turbulent flows is utilized to study flow characteristics and particle deposition with representative healthy and severe asthmatic lungs. For the subject-specific boundary condition, local air-volume changes are derived with two computed tomography images at inspiration and expiration. Particle transport simulations are performed on LES-predicted flow fields. In severe asthmatics, the elevated air-volume changes of apical lung regions affect the increased particle distribution toward upper lobes, especially for small particles. The constricted airways are significantly correlated with high wall shear stress, leading to the increased pressure drop and particle deposition. The structural alterations of bifurcation angle, circularity and hydraulic diameter in severe asthmatics are associated with the increase of particle deposition, wall shear stress and wall thickness. NIH Grants: U01-HL114494, R01-HL094315 and S10-RR022421. Computer time: XSEDE.

  4. Interleukin-1 receptor blockade improves survival and hemodynamic performance in Escherichia coli septic shock, but fails to alter host responses to sublethal endotoxemia.

    PubMed Central

    Fischer, E; Marano, M A; Van Zee, K J; Rock, C S; Hawes, A S; Thompson, W A; DeForge, L; Kenney, J S; Remick, D G; Bloedow, D C

    1992-01-01

    The present study was undertaken to evaluate the extent to which an endogenous interleukin-1 (IL-1) response contributes to the hemodynamic and metabolic consequences of sublethal endotoxemia or lethal Gram-negative septic shock. Young, healthy baboons received either a sublethal dose of lipopolysaccharide (LPS) or an LD100 of live Escherichia coli bacteria, and one half of the animals in each group were continuously infused with IL-1 receptor antagonist (IL-1ra). Plasma IL-1 beta was not detected in this model of endotoxemia. Administration of IL-1ra had only minimal effects on the modest hemodynamic and metabolic responses to sublethal endotoxemia, and did not attenuate the plasma cytokine response. In contrast, high circulating levels of IL-1 beta (range 300-800 pg/ml) were seen during lethal E. coli septic shock. IL-1ra treatment significantly attenuated the decrease in mean arterial blood pressure (MAP) (from -72 +/- 8 to -43 +/- 6 mm Hg; P less than 0.05) and cardiac output (from -0.81 +/- 0.17 to -0.48 +/- 0.15 liter/min; P less than 0.05), and significantly improved survival from 43 to 100% at 24 h (P less than 0.05). The plasma IL-1 beta and IL-6 responses to lethal E. coli septic shock were also significantly diminished by IL-1ra treatment (P less than 0.05), whereas tumor necrosis factor-alpha (TNF alpha) concentrations were unaffected. We conclude that an exaggerated systemic IL-1 beta response is characteristic of lethal E. coli septic shock, and contributes significantly to the hemodynamic and metabolic consequences of E. coli septic shock. IL-1ra can significantly attenuate the cytokine cascade and improve survival. PMID:1533231

  5. Prevalence and severity of foot pad alterations in German turkey poults during the early rearing phase.

    PubMed

    Bergmann, S; Ziegler, N; Bartels, T; Hübel, J; Schumacher, C; Rauch, E; Brandl, S; Bender, A; Casalicchio, G; Krautwald-Junghanns, M-E; Erhard, M H

    2013-05-01

    In the previously performed field study from 2007 to 2009, it became evident that foot pad alterations were already commonly found in turkeys at the age of 6 wk. At this early age, 45% of the clinically examined birds were diagnosed with epithelial necrosis. Therefore, it became important to specifically analyze the situation during the early rearing phase. The present study reflects the prevalence and severity of foot pad alterations of turkey poults up to the age of 35 d (5 wk), starting as early as the age of 3 d. From 24 turkey farms throughout Germany, in general 5,531 turkeys [3,131 male and 2,400 female] of the British United Turkeys 6 strain from 46 flocks, were examined to that effect. Prevalence and severity increased within the duration of stay in the stable, and the prevalence was higher (P < 0.001) during the second visit between d 22 to 35 (factor: 0.94). Therefore, 27.3% (d 3 to 5; male/female: 39.1/25.0%) and 63.3% (d 22 to 35: 61.3/65.7%) of the examined poults had alterations of the foot pads, such as hyperkeratosis (d 3 to 5: 20.4/14.2%; d 22 to 35: 17.6/17.1%), high-grade hyperkeratosis with adhesive dirt (d 3 to 5: 8.7/10.7%; d 22 to 35: 29.2/39.3%), and epithelial necrosis (d 3 to 5: 0.1/0.1%; d 22 to 35: 14.6/9.3%). Female poults showed a higher risk (P < 0.001) of developing food pad alterations (factor: 0.76) than male poults. Male poults developed a higher percentage of epithelial necrosis than hens shortly before relocation. A higher stocking density during the very early rearing phase (d 3 to 5) led to a worse foot pad health status (P < 0.001). Because even mild alterations in the foot pad condition can be indicators for suboptimal design of the rearing environment and are to be seen as a pre-state for severe cases of foot pad dermatitis, it is important to set the main focus on the early rearing phase. PMID:23571325

  6. Airway glutathione homeostasis is altered in children with severe asthma: Evidence for oxidant stress

    PubMed Central

    Fitzpatrick, Anne M.; Teague, W. Gerald; Holguin, Fernando; Yeh, Mary; Brown, Lou Ann S.

    2009-01-01

    Background Severe asthma is characterized by persistent airway inflammation and increased formation of reactive oxygen species. Objectives Glutathione (GSH) is an important antioxidant in the epithelial lining fluid (ELF). We hypothesized that airway GSH homeostasis was altered in children with severe asthma and was characterized by decreased GSH and increased glutathione disulfide (GSSG) concentrations. Methods Bronchoalveolar lavage was obtained from 65 children with severe asthma, including 35 children with baseline airway obstruction evidenced by FEV1 <80%. Control data were obtained from 6 children with psychogenic (habit) cough or vocal cord dysfunction undergoing diagnostic bronchoscopy and 35 healthy adult controls. GSH, GSSG, and other determinants of airway oxidative stress including glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), malondialdehyde, 8-isoprostane, and H2O2 were measured in the ELF. The ELF redox potential was calculated from GSH and GSSG by using the Nernst equation. Results: Compared with controls, subjects with severe asthma had lower airway GSH with increased GSSG despite no differences in GST, GR, and GPx activities between groups. This was accompanied by increased malondialdehyde, 8-isoprostane, and H2O2 concentrations in the ELF. GSH oxidation was most apparent in subjects with severe asthma with airway obstruction and was supported by an upward shift in the ELF GSH redox potential. Conclusion Children with severe asthma have increased biomarkers of oxidant stress in the ELF that are associated with increased formation of GSSG and a shift in the GSH redox potential toward the more oxidized state. PMID:19130935

  7. Altered hypothalamic inflammatory gene expression correlates with heat stroke severity in a conscious rodent model.

    PubMed

    Audet, Gerald N; Dineen, Shauna M; Quinn, Carrie M; Leon, Lisa R

    2016-04-15

    It has been suggested that heat-induced hypothalamic damage mediates core temperature (Tc) disturbances during heat stroke (HS) recovery; this is significant as hypothermia and/or fever have been linked to severity and overall pathological insult. However, to date there has been a lack of histological evidence in support of these claims. We hypothesized that local hypothalamic cytokines and/or chemokines, known regulators of Tc, are mediating the elevation in Tc during HS recovery even in the absence of histological damage. In experiment 1, the hypothalamus of Fischer 344 rats was examined for 84 cytokine/chemokine genes (real-time PCR) at multiple time points (Tc,Max, 1, 3, and 10 days) during mild HS recovery. In experiment 2, the hypothalamus of three different HS severities (MILD, moderate [MOD], and severe [SEV]) in rats were examined for the same genes as experiment 1 as well as six oxidative damage markers, at a single intermediate time point (1 day). Systemic cytokines were also analyzed in experiment 2 across the three severities. There were significant alterations in 25 cytokines/chemokines expression at Tc,Max, but little or no changes in expression at longer time points in experiment 1. In experiment 2 there were significant changes in gene expression in SEV rats only, with MILD and MOD rats showing baseline expression at 1 day, despite an absence of systemic cytokine expression in any severity. There was also no change in any oxidative marker of damage at 1 day, regardless of severity. In conclusion, we show only limited changes during long term recovery from HS, but demonstrate differences in hypothalamic gene expression patterns that may be driving HS pathology and morbidity. These findings contribute to our overall understanding of HS pathology in the CNS, as well as providing avenues for future pharmacological intervention. PMID:26876741

  8. Severe inflammatory bowel disease associated with congenital alteration of transforming growth factor beta signaling.

    PubMed

    Naviglio, Samuele; Arrigo, Serena; Martelossi, Stefano; Villanacci, Vincenzo; Tommasini, Alberto; Loganes, Claudia; Fabretto, Antonella; Vignola, Silvia; Lonardi, Silvia; Ventura, Alessandro

    2014-08-01

    Transforming growth factor beta is a pleiotropic cytokine which plays a central role in the homeostasis of the immune system. A complex dysregulation of its signaling occurs in Loeys-Dietz syndrome, a monogenic disorder caused by mutations of transforming growth factor beta receptors type 1 or type 2, characterized by skeletal involvement, craniofacial abnormalities, and arterial tortuosity with a strong predisposition for aneurysm and dissection. In addition, several immunologic abnormalities have been described in these patients, including an increased risk of allergic disorders as well as eosinophilic gastrointestinal disorders. The occurrence of inflammatory bowel disorders has been also reported, but it is poorly documented. We describe two unrelated children with Loeys-Dietz syndrome affected by severe chronic inflammatory colitis appearing at an early age. The intestinal disease presented similar features in both patients, including a histopathological picture of non-eosinophilic chronic ulcerative colitis, striking elevation of inflammatory markers, and a distinctly severe clinical course leading to failure to thrive, with resistance to multiple immunosuppressive treatments. One of the patients also presented autoimmune thyroiditis. Our report confirms that chronic ulcerative colitis may be associated with Loeys-Dietz syndrome. This finding suggests that an alteration of transforming growth factor beta signaling may by itself predispose to inflammatory colitis in humans, and represent an invaluable model to understand inflammatory bowel diseases. PMID:24486179

  9. Hemodynamic Intervention of Cerebral Aneurysms

    NASA Astrophysics Data System (ADS)

    Meng, Hui

    2005-11-01

    Cerebral aneurysm is a pathological vascular response to hemodynamic stimuli. Endovascular treatment of cerebral aneurysms essentially alters the blood flow to stop them from continued growth and eventual rupture. Compared to surgical clipping, endovascular methods are minimally invasive and hence rapidly gaining popularity. However, they are not always effective with risks of aneurysm regrowth and various complications. We aim at developing a Virtual Intervention (VI) platform that allows: patient-specific flow calculation and risk prediction as well as recommendation of tailored intervention based on quantitative analysis. This is a lofty goal requiring advancement in three areas of research: (1). Advancement of image-based CFD; (2) Understanding the biological/pathological responses of tissue to hemodynamic factors in the context of cerebral aneurysms; and (3) Capability of designing and testing patient-specific endovascular devices. We have established CFD methodologies based on anatomical geometry obtained from 3D angiographic or CT images. To study the effect of hemodynamics on aneurysm development, we have created a canine model of a vascular bifurcation anastomosis to provide the hemodynamic environment similar to those in CA. Vascular remodeling was studied using histology and compared against the flow fields obtained from CFD. It was found that an intimal pad, similar to those frequently seen clinically, developed at the flow impingement site, bordering with an area of `groove' characteristic of an early stage of aneurysm, where the micro environment exhibits an elevated wall shear stresses. To further address the molecular mechanisms of the flow-mediated aneurysm pathology, we are also developing in vitro cell culture systems to complement the in vivo study. Our current effort in endovascular device development focuses on novel stents that alters the aneurysmal flow to promote thrombotic occlusion as well as favorable remodeling. Realization of an

  10. Caudal anesthesia in a patient with severe pulmonary hypertension.

    PubMed

    Ly, Doanh T

    2010-06-01

    Delivery of anesthesia to patients with severe pulmonary hypertension can be extremely challenging. The profound hemodynamic alterations of the disease can often be exacerbated by alterations in circulatory function brought about by anesthetic and surgical interventions. High perioperative morbidity and mortality rates have been reported. Minimizing adverse outcomes in these patients requires careful perioperative evaluation and planning. Selection of an anesthetic technique suitable for the surgery without causing major hemodynamic alterations, which can lead to cardiac failure and death, is a unique consideration of the anesthesia provider. As shown in this case report, caudal anesthesia, when appropriate, can offer a safe anesthetic for these patients. PMID:20572406

  11. Alterations of diaphragm and rib cage morphometry in severe COPD patients by CT analysis.

    PubMed

    Salito, C; Luoni, E; Aliverti, A

    2015-08-01

    Although it is known that in patients with COPD acute hyperinflation determines shortening of the inspiratory muscles, its effects on both diaphragm and rib cage morphology are still to be investigated. In this preliminary study the relationships between hyperinflation, emphysema, diaphragm and rib cage geometry were studied in 5 severe COPD patients and 5 healthy subjects. An automatic software was developed to obtain the 3-D reconstruction of diaphragm and rib cage from CT scans taken at total lung capacity (TLC) and residual volume (RV). Dome surface area (Ado), radius of curvature, length (Ld) and position (referred to xiphoid level) of the diaphragm and antero-posterior (A-P) and transverse (T) diameters of rib cage were calculated at both volumes. Ado and Ld were similar in COPD and controls when compared at similar absolute lung volumes. Radius of curvature was significantly higher in COPD than in controls only at TLC. In COPD, the range of diaphragm position was invariantly below the xiphoid level, while in controls the top of diaphragm dome was always above it. Rib cage diameters were not different at TLC. A-P diameter was greater in COPD than in controls at RV, while T diameters were similar. In conclusion, in severe COPD diaphragm and rib cage geometry is altered at RV. The lower position of diaphragm is associated to smaller A-P but not transversal rib cage diameters, such that rib cage adopts a more circular shape. PMID:26737755

  12. Altered invertase activities of symptomatic tissues on Beet severe curly top virus (BSCTV) infected Arabidopsis thaliana.

    PubMed

    Park, Jungan; Kim, Soyeon; Choi, Eunseok; Auh, Chung-Kyun; Park, Jong-Bum; Kim, Dong-Giun; Chung, Young-Jae; Lee, Taek-Kyun; Lee, Sukchan

    2013-09-01

    Arabidopsis thaliana infected with Beet severe curly top virus (BSCTV) exhibits systemic symptoms such as stunting of plant growth, callus induction on shoot tips, and curling of leaves and shoot tips. The regulation of sucrose metabolism is essential for obtaining the energy required for viral replication and the development of symptoms in BSCTV-infected A. thaliana. We evaluated the changed transcript level and enzyme activity of invertases in the inflorescence stems of BSCTV-infected A. thaliana. These results were consistent with the increased pattern of ribulose-1,5-bisphosphate carboxylase/oxygenase activity and photosynthetic pigment concentration in virus-infected plants to supply more energy for BSCTV multiplication. The altered gene expression of invertases during symptom development was functionally correlated with the differential expression patterns of D-type cyclins, E2F isoforms, and invertase-related genes. Taken together, our results indicate that sucrose sensing by BSCTV infection may regulate the expression of sucrose metabolism and result in the subsequent development of viral symptoms in relation with activation of cell cycle regulation. PMID:23589148

  13. Altered plasma pharmacokinetics of ceftiofur hydrochloride in cows affected with severe clinical mastitis.

    PubMed

    Gorden, P J; Kleinhenz, M D; Wulf, L W; KuKanich, B; Lee, C J; Wang, C; Coetzee, J F

    2016-01-01

    Mastitis is a frequent problem among dairy cows, reducing milk yield and increasing cull rates. Systemic therapy with the cephalosporin antimicrobial ceftiofur hydrochloride (CEF) may improve therapeutic outcomes, but the incidence of CEF violative residues has increased annually since 2011. One potential explanation is that disease status may alter the pharmacokinetics (PK) of CEF. To test this hypothesis, we compared the plasma PK of CEF in healthy cows with those with severe endotoxic mastitis. Eight cows with naturally occurring mastitis and 8 clinically healthy cows were treated with 2.2 mg of CEF per kilogram of body weight once daily for 5d via the intramuscular route. Blood was collected at 0, 0.33, 0.67, 1, 1.5, 2, 3, 4, 8, 16, and 24h after the first CEF administration and every 8h thereafter until 120 h after the final dose. Plasma samples were analyzed for CEF concentrations using liquid chromatography coupled with mass spectrometry. With the exception of time 0, CEF was detected at all time points. The disease group had a significantly higher plasma CEF concentration at t=3h after the first injection and a significantly lower plasma concentration from 40 to 152 h following the first injection, with the exception of the t=64 h time point. Data following the first injection (time 0-24 h) were fit to a single-dose, noncompartmental PK model. This model indicated that the disease group had a shorter plasma half-life. A multidose, noncompartmental model was used to determine steady-state PK. Compared with control cows, the disease group had an initially higher peak concentration and a higher volume of distribution and drug clearance rates. The disease group also had a lower area under the curve per dosing interval, steady-state concentration maximum, and dose-adjusted peak steady-state concentration. All other PK parameters were not different between the 2 groups. Altered PK, as suggested by this trial, may contribute to an increased risk for the

  14. Loss of Bace1 in Mice Does Not Alter the Severity of Caerulein Induced Pancreatitis

    PubMed Central

    Heindl, Mario; Tuennemann, Jan; Sommerer, Ines; Mössner, Joachim; Hoffmeister, Albrecht

    2015-01-01

    Context Beta-site alpha-amyloid protein cleaving enzyme1 (BACE1) plays a key role in the pathogenesis of Alzheimer’s disease. Additional to its moderate expression in the brain, high levels of BACE1 mRNA were found in the pancreas. Murine Bace1 has been immunohistochemicaly detected at the apical pole of acinar cells within the exocrine pancreas of mice and Bace1 activity was observed in pancreatic juice. In vitro experiments revealed enteropeptidase as a putative substrate for Bace1 suggesting a role in acute pancreatitis. Objective The aim of this study was to address a protective mechanism of Bace1 in acute experimental pancreatitis in mice. Methods Acute experimental pancreatitis was induced by intraperitoneal injection of caerulein in homozygote Bace1-/- mice and wild type mice. Serum and tissue analyses were carried out after 4 h, 8 h and 24 h. Measurement of plasma amylase and lipase was performed to confirm pancreatitis induction. In order to assess the severity of pancreatitis H&E stained pancreatic sections were examined regarding edema, inflammation and apoptosis. Immunohistochemical detection of myeloperoxidase (MPO) positive cells was carried out to further quantify the extent of inflammation. Expression of Bace2 within the pancreas was analyzed by immunohistochemistry and RT-qPCR. Results We demonstrate that total loss of Bace1 in mice leads to no alterations in the course of acute experimental caerulein-pancreatitis. Bace1-/- mice develop a moderate pancreatitis that is comparable in histomorphological and serological features with those seen in wild type mice. Discussion We discuss the results in the context of the applied caerulein induced edematous pancreatitis model and possible compensatory mechanisms via Bace2 that might be responsible for the observed results. PMID:25961820

  15. Invasive hemodynamics of constrictive pericarditis

    PubMed Central

    Doshi, Shrenik; Ramakrishnan, Sivasubramanian; Gupta, Saurabh Kumar

    2015-01-01

    Cardiac catheterization and hemodynamic study is the gold standard for the diagnosis of pericardial constriction. Careful interpretation of the hemodynamic data is essential to differentiate it from other diseases with restrictive physiology. In this hemodynamic review we shall briefly discuss the physiologic basis of various hemodynamic changes seen in a patient with constrictive pericarditis. PMID:26071303

  16. Effect of ultra-fast mild hypothermia using total liquid ventilation on hemodynamics and respiratory mechanics.

    PubMed

    Sage, Michaël; Nadeau, Mathieu; Kohlhauer, Matthias; Praud, Jean-Paul; Tissier, Renaud; Robert, Raymond; Walti, Hervé; Micheau, Philippe

    2016-08-01

    Ultra-fast cooling for mild therapeutic hypothermia (MTH) has several potential applications, including prevention of post-cardiac arrest syndrome. Ultra-fast MTH by total liquid ventilation (TLV) entails the sudden filling of the lungs with a cold perfluorocarbon liquid and its subsequent use to perform TLV. The present physiological study was aimed at assessing whether pulmonary and systemic hemodynamics as well as lung mechanics are significantly altered during this procedure. Pulmonary and systemic arterial pressures, cardiac output as well as airway resistance and respiratory system compliance were measured during ultra-fast MTH by TLV followed by rewarming and normothermia in six healthy juvenile lambs. Results show that none of the studied variables were altered upon varying the perfluorocarbon temperature from 12 to 41 °C. It is concluded that ultra-fast MTH by TLV does not have any deleterious effect on hemodynamics or lung mechanics in healthy juvenile lambs. PMID:27242031

  17. Functional hemodynamic monitoring

    PubMed Central

    Pinsky, Michael R; Payen, Didier

    2005-01-01

    Hemodynamic monitoring is a central component of intensive care. Patterns of hemodynamic variables often suggest cardiogenic, hypovolemic, obstructive, or distributive (septic) etiologies to cardiovascular insufficiency, thus defining the specific treatments required. Monitoring increases in invasiveness, as required, as the risk for cardiovascular instability-induced morbidity increases because of the need to define more accurately the diagnosis and monitor the response to therapy. Monitoring is also context specific: requirements during cardiac surgery will be different from those in the intensive care unit or emergency department. Solitary hemodynamic values are useful as threshold monitors (e.g. hypotension is always pathological, central venous pressure is only elevated in disease). Some hemodynamic values can only be interpreted relative to metabolic demand, whereas others have multiple meanings. Functional hemodynamic monitoring implies a therapeutic application, independent of diagnosis such as a therapeutic trial of fluid challenge to assess preload responsiveness. Newer methods for assessing preload responsiveness include monitoring changes in central venous pressure during spontaneous inspiration, and variations in arterial pulse pressure, systolic pressure, and aortic flow variation in response to vena caval collapse during positive pressure ventilation or passive leg raising. Defining preload responsiveness using these functional measures, coupled to treatment protocols, can improve outcome from critical illness. Potentially, as these and newer, less invasive hemodynamic measures are validated, they could be incorporated into such protocolized care in a cost-effective manner. PMID:16356240

  18. Alterations in the Composition of the Supramucosal Defense Barrier in Relation to Disease Severity of Ulcerative Colitis

    PubMed Central

    Longman, Rob J.; Poulsom, Richard; Corfield, Anthony P.; Warren, Bryan F.; Wright, Nicholas A.; Thomas, Michael G.

    2006-01-01

    Mucin glycoproteins and trefoil peptides play an important role in protection and repair of the gastrointestinal epithelium. This study investigates alterations in mucin and trefoil peptide gene expression and product localization in ulcerative colitis (UC). Product localization and message expression of mucin MUC1 to 6 and trefoil peptide TFF1 to 3 genes was analyzed in rectosigmoid tissue from a cohort of patients with active UC and compared with that of normal colorectal mucosa. MUC1 expression was upregulated in severe UC at the site of rupture of crypt abscesses. Reduction in MUC2 expression occurred in UC adjacent to ulceration. No alteration in MUC3 or MUC4 gene expression was detectable in UC compared with normal colorectal mucosa. No ectopic expression of MUC5AC, MUC5B, or MUC6 was identified in UC. Ectopic TFF1 expression was identified in tissues eliciting histological features of severe disease. Decreased TFF3 localization was demonstrated in UC tissues, but no TFF2 expression was detected in any colorectal specimens. Subtle alterations in composition of the supramucosal defense barrier exist in UC and vary in relation to clinical severity of disease. There is upregulation in mucin MUC1 at crypt abscesses and neo-expression of TFF1 trefoil peptide in severe disease. PMID:16924127

  19. Hemodynamics of Cerebral Aneurysms

    PubMed Central

    Sforza, Daniel M.; Putman, Christopher M.; Cebral, Juan Raul

    2009-01-01

    The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns. PMID:19784385

  20. Exposure to ozone reduces influenza disease severity and alters distribution of influenza viral antigens in murine lungs.

    PubMed

    Wolcott, J A; Zee, Y C; Osebold, J W

    1982-09-01

    Exposure to ambient levels of ozone (0.5 ppm) was shown to alter the pathogenesis of respiratory infection after aerosol infection of mice with influenza A virus. A semiquantitative method for determination of the sites of virus replication by direct immunofluorescence indicated that exposure to ozone reduced the involvement of respiratory epithelium in the infectious process and resulted in a less widespread infection of the alveolar parenchyma. Furthermore, the ozone-mediated alteration in viral antigen distribution was consistent with significantly reduced influenza disease mortality and prolonged survival time, but only when the oxidant was present during the course of infection. Reduced disease severity in ozone-exposed animals appeared to be independent of peak pulmonary virus titers, pulmonary interferon titers, and pulmonary and serum-neutralizing antibody titers. These studies suggested that the distribution of influenza virus in the murine lung was a key factor in disease severity. PMID:6182839

  1. Severe COPD Alters Muscle Fiber Conduction Velocity During Knee Extensors Fatiguing Contraction.

    PubMed

    Boccia, Gennaro; Coratella, Giuseppe; Dardanello, Davide; Rinaldo, Nicoletta; Lanza, Massimo; Schena, Federico; Rainoldi, Alberto

    2016-10-01

    The aim of this study was to assess the changes in muscle fiber conduction velocity (CV), as a sign of fatigue during knee extensor contraction in patients with chronic obstructive pulmonary disease (COPD) as compared with healthy controls. Eleven male patients (5 with severe and 6 with moderate COPD; age 67 ± 5 years) and 11 age-matched healthy male controls (age 65 ± 4 years) volunteered for the study. CV was obtained by multichannel surface electromyography (EMG) from the vastus lateralis (VL) and medialis (VM) of the quadriceps muscle during isometric, 30-second duration knee extension at 70% of maximal voluntary contraction. The decline in CV in both the VL and VM was steeper in the severe COPD patients than in healthy controls (for VL: severe COPD vs. controls -0.45 ± 0.07%/s; p < 0.001, and for VM: severe COPD vs. controls -0.54 ± 0.09%/s, p < 0.001). No difference in CV decline was found between the moderate COPD patients and the healthy controls. These findings suggest that severe COPD may impair muscle functions, leading to greater muscular fatigue, as expressed by CV changes. The results may be due to a greater involvement of anaerobic metabolism and a shift towards fatigable type II fibers in the muscle composition of the severe COPD patients. PMID:27007486

  2. Hemodynamic studies of the legs under weightlessness

    NASA Technical Reports Server (NTRS)

    Thornton, W. E.; Hoffler, G. W.

    1977-01-01

    Significant among the medical findings following prolonged space flight are reduced orthostatic tolerance and ergometric work capacity. Changes in hemodynamics of the legs with increased blood pooling and reduction in cardiac output must be considered one of the most probable causes of these effects. Concern for the above plus the observed marked tissue changes occurring in the legs during flight prompted the addition of several procedures to evaluate hemodynamic changes in the leg; resting arterial blood flow, venous compliance and muscle pumping were investigated. In so far as possible, the initial reaction to pressure in the smallest possible vein segment was examined.

  3. Altered interhemispheric and temporal lobe white matter microstructural organization in severe chronic schizophrenia.

    PubMed

    Holleran, Laurena; Ahmed, Mohamed; Anderson-Schmidt, Heike; McFarland, John; Emsell, Louise; Leemans, Alexander; Scanlon, Cathy; Dockery, Peter; McCarthy, Peter; Barker, Gareth J; McDonald, Colm; Cannon, Dara M

    2014-03-01

    Diffusion MRI investigations in schizophrenia provide evidence of abnormal white matter (WM) microstructural organization as indicated by reduced fractional anisotropy (FA) primarily in interhemispheric, left frontal and temporal WM. Using tract-based spatial statistics (TBSS), we examined diffusion parameters in a sample of patients with severe chronic schizophrenia. Diffusion MRI data were acquired on 19 patients with chronic severe schizophrenia and 19 age- and gender-matched healthy controls using a 64 gradient direction sequence, (b=1300 s/mm(2)) collected on a Siemens 1.5T MRI scanner. Diagnosis of schizophrenia was determined by Diagnostic and Statistical Manual for Mental Disorders 4th Edition (DSM-IV) Structured Clinical Interview for DSM disorder (SCID). Patients were treatment resistance, having failed to respond to at least two antipsychotic medications, and had prolonged periods of moderate to severe positive or negative symptoms. Analysis of diffusion parameters was carried out using TBSS. Individuals with chronic severe schizophrenia had significantly reduced FA with corresponding increased radial diffusivity in the genu, body, and splenium of the corpus callosum, the right posterior limb of the internal capsule, right external capsule, and the right temporal inferior longitudinal fasciculus. There were no voxels of significantly increased FA in patients compared with controls. A decrease in splenium FA was shown to be related to a longer illness duration. We detected widespread abnormal diffusivity properties in the callosal and temporal lobe WM regions in individuals with severe chronic schizophrenia who have not previously been exposed to clozapine. These deficits can be driven by a number of factors that are indistinguishable using in vivo diffusion-weighted imaging, but may be related to reduced axonal number or packing density, abnormal glial cell arrangement or function, and reduced myelin. PMID:24150571

  4. Diets enriched with cranberry beans alter the microbiota and mitigate colitis severity and associated inflammation.

    PubMed

    Monk, Jennifer M; Lepp, Dion; Zhang, Claire P; Wu, Wenqing; Zarepoor, Leila; Lu, Jenifer T; Pauls, K Peter; Tsao, Rong; Wood, Geoffrey A; Robinson, Lindsay E; Power, Krista A

    2016-02-01

    Common beans are rich in phenolic compounds and nondigestible fermentable components, which may help alleviate intestinal diseases. We assessed the gut health priming effect of a 20% cranberry bean flour diet from two bean varieties with differing profiles of phenolic compounds [darkening (DC) and nondarkening (NDC) cranberry beans vs. basal diet control (BD)] on critical aspects of gut health in unchallenged mice, and during dextran sodium sulfate (DSS)-induced colitis (2% DSS wt/vol, 7 days). In unchallenged mice, NDC and DC increased (i) cecal short-chain fatty acids, (ii) colon crypt height, (iii) crypt goblet cell number and mucus content and (iv) Muc1, Klf4, Relmβ and Reg3γ gene expression vs. BD, indicative of enhanced microbial activity and gut barrier function. Fecal 16S rRNA sequencing determined that beans reduced abundance of the Lactobacillaceae (Ruminococcus gnavus), Clostridiaceae (Clostridium perfringens), Peptococcaceae, Peptostreptococcaceae, Rikenellaceae and Pophyromonadaceae families, and increased abundance of S24-7 and Prevotellaceae. During colitis, beans reduced (i) disease severity and colonic histological damage, (ii) increased gene expression of barrier function promoting genes (Muc1-3, Relmβ, and Reg3γ) and (iii) reduced colonic and circulating inflammatory cytokines (IL-1β, IL-6, IFNγ and TNFα). Therefore, prior to disease induction, bean supplementation enhanced multiple concurrent gut health promoting parameters that translated into reduced colitis severity. Moreover, both bean diets exerted similar effects, indicating that differing phenolic content did not influence the endpoints assessed. These data demonstrate a proof-of-concept regarding the gut-priming potential of beans in colitis, which could be extended to mitigate the severity of other gut barrier-associated pathologies. PMID:26878790

  5. Altered Mucosal Microbiome Diversity and Disease Severity in Sjögren Syndrome.

    PubMed

    de Paiva, Cintia S; Jones, Dan B; Stern, Michael E; Bian, Fang; Moore, Quianta L; Corbiere, Shani; Streckfus, Charles F; Hutchinson, Diane S; Ajami, Nadim J; Petrosino, Joseph F; Pflugfelder, Stephen C

    2016-01-01

    There is mounting evidence that the microbiome has potent immunoregulatory functions. We assessed the effects of intestinal dysbiosis in a model of Sjögren syndrome (SS) by subjecting mice to desiccating stress (DS) and antibiotics (ABX). We characterized the conjunctival, tongue and fecal microbiome profiles of patients with SS. Severity of ocular surface and systemic disease was graded. 16S ribosomal RNA gene sequencing characterized the microbiota. ABX + DS mice had a significantly worse dry eye phenotype compared to controls, a decrease in Clostridium and an increase in Enterobacter, Escherichia/Shigella, and Pseudomonas in stool after ABX + DS for 10 days. Goblet cell density was significantly lower in ABX treated groups compared to controls. Stool from SS subjects had greater relative abundances of Pseudobutyrivibrio, Escherichia/Shigella, Blautia, and Streptococcus, while relative abundance of Bacteroides, Parabacteroides, Faecalibacterium, and Prevotella was reduced compared to controls. The severity of SS ocular and systemic disease was inversely correlated with microbial diversity. These findings suggest that SS is marked by a dysbiotic intestinal microbiome driven by low relative abundance of commensal bacteria and high relative abundance of potentially pathogenic genera that is associated with worse ocular mucosal disease in a mouse model of SS and in SS patients. PMID:27087247

  6. Altered Mucosal Microbiome Diversity and Disease Severity in Sjögren Syndrome

    PubMed Central

    de Paiva, Cintia S.; Jones, Dan B.; Stern, Michael E.; Bian, Fang; Moore, Quianta L.; Corbiere, Shani; Streckfus, Charles F.; Hutchinson, Diane S.; Ajami, Nadim J.; Petrosino, Joseph F.; Pflugfelder, Stephen C.

    2016-01-01

    There is mounting evidence that the microbiome has potent immunoregulatory functions. We assessed the effects of intestinal dysbiosis in a model of Sjögren syndrome (SS) by subjecting mice to desiccating stress (DS) and antibiotics (ABX). We characterized the conjunctival, tongue and fecal microbiome profiles of patients with SS. Severity of ocular surface and systemic disease was graded. 16S ribosomal RNA gene sequencing characterized the microbiota. ABX + DS mice had a significantly worse dry eye phenotype compared to controls, a decrease in Clostridium and an increase in Enterobacter, Escherichia/Shigella, and Pseudomonas in stool after ABX + DS for 10 days. Goblet cell density was significantly lower in ABX treated groups compared to controls. Stool from SS subjects had greater relative abundances of Pseudobutyrivibrio, Escherichia/Shigella, Blautia, and Streptococcus, while relative abundance of Bacteroides, Parabacteroides, Faecalibacterium, and Prevotella was reduced compared to controls. The severity of SS ocular and systemic disease was inversely correlated with microbial diversity. These findings suggest that SS is marked by a dysbiotic intestinal microbiome driven by low relative abundance of commensal bacteria and high relative abundance of potentially pathogenic genera that is associated with worse ocular mucosal disease in a mouse model of SS and in SS patients. PMID:27087247

  7. Optical imaging of neural and hemodynamic brain activity

    NASA Astrophysics Data System (ADS)

    Schei, Jennifer Lynn

    Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic

  8. Age-Related Alteration of Arginase Activity Impacts on Severity of Leishmaniasis

    PubMed Central

    Müller, Ingrid; Hailu, Asrat; Choi, Beak-San; Abebe, Tamrat; Fuentes, Jose M.; Munder, Markus; Modolell, Manuel; Kropf, Pascale

    2008-01-01

    Background The leishmaniases are a group of vector-borne parasitic diseases that represent a major international public health problem; they belong to the most neglected tropical diseases and have one of the highest rates of morbidity and mortality. The clinical outcome of infection with Leishmania parasites depends on a variety of factors such as parasite species, vector-derived products, genetics, behaviour, and nutrition. The age of the infected individuals also appears to be critical, as a significant proportion of clinical cases occur in children; this age-related higher prevalence of disease is most remarkable in visceral leishmaniasis. The mechanisms resulting in this higher incidence of clinical disease in children are poorly understood. We have recently revealed that sustained arginase activity promotes uncontrolled parasite growth and pathology in vivo. Here, we tested the hypothesis that arginase-mediated L-arginine metabolism differs with age. Methodology The age distribution of patients with visceral or cutaneous leishmaniasis was determined in cohorts of patients in our clinics in endemic areas in Ethiopia. To exclude factors that are difficult to control in patients, we assessed the impact of ageing on the manifestations of experimental leishmaniasis. We determined parasite burden, T cell responses, and macrophage effector functions in young and aged mice during the course of infection. Results Our results show that younger mice develop exacerbated lesion pathology and higher parasite burdens than aged mice. This aggravated disease development in younger individuals does not correlate with a change in T helper cytokine profile. To address the underlying mechanisms responsible for the more severe infections in younger mice, we investigated macrophage effector functions. Our results show that macrophages from younger mice do not have an impaired capacity to kill parasites; however, they express significantly higher levels of arginase 1 than aged mice

  9. A dose-responsive model of smoke inhalation injury. Severity-related alteration in cardiopulmonary function.

    PubMed Central

    Shimazu, T; Yukioka, T; Hubbard, G B; Langlinais, P C; Mason, A D; Pruitt, B A

    1987-01-01

    The dose responsiveness of selected physiologic indices was studied in a sheep model of smoke inhalation injury. In this model, graded severity of injury was achieved by changing the contact time with smoke (defined by "unit"), whereas other variables were kept constant. Blood gas and cardiopulmonary indices were measured in 70 sheep, including 12 controls, either 24 or 72 hours after exposure to 3, 6, 9, 12, 15, or 18 units of smoke. A 12-unit dose of smoke was fatal within 72 hours and an 18-unit dose was fatal within 24 hours. The best correlation between smoke dose and response was observed in arterial oxygen tension 24 hours after exposure. At 24 hours, most of the cardiopulmonary indices showed significant change only after a 12-unit exposure. Although the exact shape of the dose-response curve could not be defined, sigmoid or curved linear shape was suggested, reflecting the progressive deterioration. Images Fig. 3. Fig. 4A. Fig. 4B. PMID:3606236

  10. Altered lipid metabolism in Hfe-knockout mice promotes severe NAFLD and early fibrosis.

    PubMed

    Tan, Terrence C H; Crawford, Darrell H G; Jaskowski, Lesley A; Murphy, Therese M; Heritage, Mandy L; Subramaniam, V Nathan; Clouston, Andrew D; Anderson, Gregory J; Fletcher, Linda M

    2011-11-01

    The HFE protein plays a crucial role in the control of cellular iron homeostasis. Steatosis is commonly observed in HFE-related iron-overload disorders, and current evidence suggests a causal link between iron and steatosis. Here, we investigated the potential contribution of HFE mutations to hepatic lipid metabolism and its role in the pathogenesis of nonalcoholic fatty liver disease. Wild-type (WT) and Hfe knockout mice (Hfe(-/-)) were fed either standard chow, a monounsaturated low fat, or a high-fat, high-carbohydrate diet (HFD) and assessed for liver injury, body iron status, and markers of lipid metabolism. Despite hepatic iron concentrations and body weights similar to WT controls, Hfe(-/-) mice fed the HFD developed severe hypoxia-related steatohepatitis, Tnf-α activation, and mitochondrial respiratory complex and antioxidant dysfunction with early fibrogenesis. These features were associated with an upregulation in the expression of genes involved in intracellular lipid synthesis and trafficking, while transcripts for mitochondrial fatty acid β-oxidation and adiponectin signaling-related genes were significantly attenuated. In contrast, HFD-fed WT mice developed bland steatosis only, with no inflammation or fibrosis and no upregulation of lipogenesis-related genes. A HFD led to reduced hepatic iron in Hfe(-/-) mice compared with chow-fed mice, despite higher serum iron, decreased hepcidin expression, and increased duodenal ferroportin mRNA. In conclusion, our results demonstrate that Hfe(-/-) mice show defective hepatic-intestinal iron and lipid signaling, which predispose them toward diet-induced hepatic lipotoxicity, accompanied by an accelerated progression of injury to fibrosis. PMID:21817060

  11. Altered mean platelet volume in patients with polymyositis and its association with disease severity

    PubMed Central

    Peng, Y.-F.; Huang, Y.-X.; Wei, Y.-S.

    2016-01-01

    Polymyositis (PM) is an autoimmune disease characterized by chronic inflammation in skeletal muscle. Mean platelet volume (MPV), a marker in the assessment of systemic inflammation, is easily measured by automatic blood count equipment. However, to our knowledge, there are no data in the literature with respect to MPV levels in PM patients. Therefore, in this study we aimed to investigate MPV levels in patients with PM. This study included 92 newly diagnosed PM patients and 100 healthy individuals. MPV levels were found to be significantly lower compared with healthy controls (10.3±1.23 vs 11.5±0.74 fL, P<0.001). Interestingly, MPV was found to be positively correlated with manual muscle test (MMT) score and negatively correlated with erythrocyte sedimentation rate (ESR) in patients with PM (r=0.239, P=0.022; r=−0.268, P=0.010, respectively). In addition, MPV was significantly lower in active PM patients compared with inactive PM patients (9.9±1.39 vs 10.6±0.92 fL, P=0.010). MPV was independently associated with PM in multivariate regression analyses, when controlling for hemoglobin and ESR (OR=0.312, P=0.031, 95%CI=0.108 to 0.899). The ROC curve analysis for MPV in estimating PM patients resulted in an area under the curve of 0.800, with sensitivity of 75.0% and specificity of 67.4%. Our results suggest that MPV is inversely correlated with disease activity in patients with PM. MPV might be a useful tool for rapid assessment of disease severity in PM patients. PMID:27191605

  12. Altered cortical thickness related to clinical severity but not the untreated disease duration in schizophrenia.

    PubMed

    Xiao, Yuan; Lui, Su; Deng, Wei; Yao, Li; Zhang, Wenjing; Li, Shiguang; Wu, Min; Xie, Teng; He, Yong; Huang, Xiaoqi; Hu, Junmei; Bi, Feng; Li, Tao; Gong, Qiyong

    2015-01-01

    Although previous studies have reported deficits in the gray matter volume of schizophrenic patients, it remains unclear whether these deficits occur at the onset of the disease, before treatment, and whether they are progressive over the duration of untreated disease. Furthermore, the gray matter volume represents the combinations of cortical thickness and surface area; these features are believed to be influenced by different genetic factors. However, cortical thickness and surface area in antipsychotic-naive first-episode schizophrenic patients have seldom been investigated. Here, the cortical thicknesses and surface areas of 128 antipsychotic-naive first-episode schizophrenic patients were compared with 128 healthy controls. The patients exhibited significantly lower cortical thickness, primarily in the bilateral prefrontal and parietal cortex, and increased thickness in the bilateral anterior temporal lobes, left medial orbitofrontal cortex, and left cuneus. Furthermore, decreased cortical thickness was related to positive schizophrenia symptoms but not to the severity of negative symptoms and the untreated disease duration. No significant difference of surface area was observed between the 2 groups. Thus, without the confounding factors of medication and illness progression, this study provides further evidence to support anatomical deficits in the prefrontal and parietal cortex early in course of the illness. The increased thicknesses of the bilateral anterior temporal lobes may represent a compensatory factor or may be an early-course neuronal pathology caused by preapoptotic osmotic changes or hypertrophy. Furthermore, these anatomical deficits are crucial to the pathogenesis of positive symptoms and relatively stable instead of progressing during the early stages of the disease. PMID:24353097

  13. Hemodynamics in fetal arrhythmia.

    PubMed

    Sonesson, Sven-Erik; Acharya, Ganesh

    2016-06-01

    Fetal arrhythmias are among the few conditions that can be managed in utero. However, accurate diagnosis is essential for appropriate management. Ultrasound-based imaging methods can be used to study fetal heart structure and function noninvasively and help to understand fetal cardiovascular pathophysiology, and they remain the mainstay of evaluating fetuses with arrhythmias in clinical settings. Hemodynamic evaluation using Doppler echocardiography allows the elucidation of the electrophysiological mechanism and helps to make an accurate diagnosis. It can also be used as a tool to understand fetal cardiac pathophysiology, for assessing fetal condition and monitoring the effect of antiarrhythmic treatment. This narrative review describes Doppler techniques that are useful for evaluating fetal cardiac rhythms to refine diagnosis and provides an overview of hemodynamic changes observed in different types of fetal arrhythmia. PMID:26660845

  14. Functional Hemodynamic Monitoring

    PubMed Central

    Pinsky, Michael R.

    2014-01-01

    Functional hemodynamic monitoring is the assessment of the dynamic interactions of hemodynamic variables in response to a defined perturbation. Dynamic tissue O2 saturation (StO2) responses to complete stop flow conditions (vascular occlusion test), which can be created by measuring hand StO2 and occluding flow with a blood pressure cuff, assesses cardiovascular sufficiency and microcirculatory blood flow distribution. Recent interest in functional hemodynamic monitoring for the bedside assessment of cardiovascular insufficiency has heightened with the documentation of its accuracy in predicting volume responsiveness using a wide variety of monitoring devices both invasive and non-invasive and across multiple patient groups and clinical conditions. Accordingly, fluid responsiveness can be predicted in a quantities fashion by measuring as arterial pulse pressure variation, left ventricular stroke volume variation or their surrogates during positive pressure breathing or the change in cardiac output response to a passive leg raising maneuver. However, volume responsiveness, though important, reflects only part of the overall spectrum of functional physiological variables that can be measured to define physiologic state and monitor response to therapy. PMID:25435480

  15. Jogging Therapy for Hikikomori Social Withdrawal and Increased Cerebral Hemodynamics: A Case Report

    PubMed Central

    Nishida, Masaki; Kikuchi, Senichiro; Fukuda, Kazuhito; Kato, Satoshi

    2016-01-01

    Severe social withdrawal, called hikikomori, has drawn increased public attention. However, an optimal clinical approach and strategy of treatment has not been well established. Here, we report a case of hikikomori for which an exercise intervention using jogging therapy was effective, showing cerebral hemodynamic improvement. The patient was a 20 year old Japanese male who was hospitalized in order to evaluate and treat severe social withdrawal. Although depressive and anxiety symptoms partially subsided with sertraline alone, social withdrawal persisted due to a lack of self confidence. With his consent, we implemented exercise therapy with 30 minutes of jogging three times a week for three months. We did not change the pharmacotherapy, and his social withdrawal remarkably improved with continuous jogging exercise. Using near infrared spectroscopy to evaluate hemodynamic alteration, bilateral temporal hemodynamics considerably increased after the three-month jogging therapy. Regarding exercise therapy for mental illness, numerous studies have reported the effectiveness of exercise therapy for major depression. This case implied, however, that the applicability of exercise therapy is not limited to major depressive disorder. Jogging therapy may contribute to reinforcing self confidence associated with “resilience” in conjunction with neurophysiological modulation of neural networks. PMID:27346999

  16. Two hemodynamic problems commonly associated with the microsphere technique for measuring regional blood flow in rats

    SciTech Connect

    Stanek, K.A.; Coleman, T.G.; Smith, T.L.; Murphy, W.R.

    1985-04-01

    The purpose of this study was to reevaluate two major steps associated with the radioactive microsphere technique in rats; the hemodynamic effects of the solutions used to inject the microspheres, and the hemodynamic effects of repeated blood withdrawals. With regard to the first, Flaim et al. have shown that 1.0 ml of 10% dextran injected into the rat may result in a severe pressure drop. The present study showed that even 0.1 ml of 10% dextran caused significant hypotension 46% of the time. Six other mediums were also tested as possible suspending media. It was concluded that a dextrose solution (sp gr 1.3) was the best microsphere injection medium based on the length of time the microspheres stayed mixed in the solution and the minimal hemodynamic alterations caused during injection. With regard to the second concern, cardiac output decreased approximately 7% with each reference sample withdrawal. When volume was replaced with a Ficoll-70 solution, cardiac output decreased less than 3%. These data show that repeated blood withdrawals are possible as long as the volume of blood is replaced. Thus, several isotopes can be injected in the same rat to allow measurement of regional blood flow under different experimental conditions.

  17. Jogging Therapy for Hikikomori Social Withdrawal and Increased Cerebral Hemodynamics: A Case Report.

    PubMed

    Nishida, Masaki; Kikuchi, Senichiro; Fukuda, Kazuhito; Kato, Satoshi

    2016-01-01

    Severe social withdrawal, called hikikomori, has drawn increased public attention. However, an optimal clinical approach and strategy of treatment has not been well established. Here, we report a case of hikikomori for which an exercise intervention using jogging therapy was effective, showing cerebral hemodynamic improvement. The patient was a 20 year old Japanese male who was hospitalized in order to evaluate and treat severe social withdrawal. Although depressive and anxiety symptoms partially subsided with sertraline alone, social withdrawal persisted due to a lack of self confidence. With his consent, we implemented exercise therapy with 30 minutes of jogging three times a week for three months. We did not change the pharmacotherapy, and his social withdrawal remarkably improved with continuous jogging exercise. Using near infrared spectroscopy to evaluate hemodynamic alteration, bilateral temporal hemodynamics considerably increased after the three-month jogging therapy. Regarding exercise therapy for mental illness, numerous studies have reported the effectiveness of exercise therapy for major depression. This case implied, however, that the applicability of exercise therapy is not limited to major depressive disorder. Jogging therapy may contribute to reinforcing self confidence associated with "resilience" in conjunction with neurophysiological modulation of neural networks. PMID:27346999

  18. The Impact of the Geometric Characteristics on the Hemodynamics in the Stenotic Coronary Artery

    PubMed Central

    Xian, Zhanchao; Liu, Xin; Huang, Wenhua; Xu, Pengcheng; Wang, Jinyang

    2016-01-01

    The alterations of the hemodynamics in the coronary arteries, which result from patient-specific geometric significances are complex. The effect of the stenosis on the blood flow alteration had been wildly reported, but the combinational contribution from geometric factors required a comprehensive investigation to provide patient-specific information for diagnosis and assisting in the decision on the further treatment strategies. In the present study, we investigated the correlation between hemodynamic parameters and individual geometric factors in the patient-specific coronary arteries. Computational fluid dynamic simulations were performed on 22 patient-specific 3-dimensional coronary artery models that were reconstructed based on computed tomography angiography images. Our results showed that the increasing severity of the stenosis is associated with the increased maximum wall shear stress at the stenosis region (r = 0.752, P < 0.001). In contrast, the length of the recirculation zone has a moderate association with the curvature of the lesion segment (r = 0.505, P = 0.019) and the length of the lesions (r = 0.527, P = 0.064). Moreover, bifurcation in the coronary arteries is significantly correlated with the occurrence of recirculation, whereas the severity of distal stenosis demonstrated an effect on the alteration of the flow in the upstream bifurcation. These findings could serve as an indication for treatment planning and assist in prognosis evaluation. PMID:27310014

  19. Invasive hemodynamic monitoring.

    PubMed

    Magder, Sheldon

    2015-01-01

    Although invasive hemodynamic monitoring requires considerable skill, studies have shown a striking lack of knowledge of the measurements obtained with the pulmonary artery catheter (PAC). This article reviews monitoring using a PAC. Issues addressed include basic physiology that determines cardiac output and blood pressure; methodology in the measurement of data obtained from a PAC; use of the PAC in making a diagnosis and for patient management, with emphasis on a responsive approach to management; and uses of the PAC that are not indications by themselves for placing the catheter, but can provide useful information when a PAC is in place. PMID:25435479

  20. Growth and hemodynamics after early embryonic aortic arch occlusion*

    PubMed Central

    Lindsey, Stephanie E.; Menon, Prahlad G.; Kowalski, William J.; Shekhar, Akshay; Yalcin, Huseyin C.; Nishimura, Nozomi; Schaffer, Chris B.; Butcher, Jonathan T.; Pekkan, Kerem

    2015-01-01

    The majority of severe clinically significant forms of congenital heart disease (CHD) is associated with great artery lesions, including hypoplastic, double, right or interrupted aortic arch morphologies. While fetal and neonatal interventions are advancing, their potential ability to restore cardiac function, optimal timing, location, and intensity required for intervention remain largely unknown. We here combine computational fluid dynamics (CFD) simulations with in vivo experiments to test how individual pharyngeal arch artery hemodynamics alters as a result of local interventions to obstruct individual arch artery flow. Simulated isolated occlusions within each pharyngeal arch artery were created with image derived three-dimensional (3D) reconstructions of normal chick pharyngeal arch anatomy at Hamburger-Hamilton (HH) developmental stages HH18 and HH24. Acute flow redistributions were then computed using in vivo measured subject-specific aortic sinus inflow velocity profiles. A kinematic vascular growth-rendering algorithm was then developed and implemented to test the role of changing local wall shear stress patterns in downstream 3D morphogenesis of arch arteries. CFD simulations predicted that altered pressure gradients and flow redistributions were most sensitive to occlusion of the IVth arches. To evaluate these simulations experimentally, a novel in vivo experimental model of pharyngeal arch occlusion was developed and implemented using two-photon microscopy guided femtosecond laser based photodisruption surgery. The right IVth arch was occluded at HH18, and resulting diameter changes were followed for up to 24 hours. Pharyngeal arch diameter responses to acute hemodynamic changes were predicted qualitatively but poorly quantitatively. Chronic growth and adaptation to hemodynamic changes however were predicted in a subset of arches. Our findings suggest that this complex biodynamic process is governed through more complex forms of mechanobiological

  1. Functional Metabolomics Uncovers Metabolic Alterations Associated to Severe Oxidative Stress in MCF7 Breast Cancer Cells Exposed to Ascididemin

    PubMed Central

    Morvan, Daniel

    2013-01-01

    Marine natural products are a source of promising agents for cancer treatment. However, there is a need to improve the evaluation of their mechanism of action in tumors. Metabolomics of the response to anti-tumor agents is a tool to reveal candidate biomarkers and metabolic targets. We used two-dimensional high-resolution magic angle spinning proton-NMR spectroscopy-based metabolomics to investigate the response of MCF7 breast cancer cells to ascididemin, a marine alkaloid and lead molecule for anti-cancer treatment. Ascididemin induced severe oxidative stress and apoptosis within 48 h of exposure. Thirty-three metabolites were quantified. Metabolic response involved downregulation of glycolysis and the tricarboxylic acid cycle, and phospholipid metabolism alterations. Candidate metabolic biomarkers of the response of breast cancer cells to ascididemin were proposed including citrate, gluconate, polyunsaturated fatty acids, glycerophospho-choline and -ethanolamine. In addition, candidate metabolic targets were identified. Overall, the response to Asc could be related to severe oxidative stress and anti-inflammatory effects. PMID:24152560

  2. Global detection of molecular changes reveals concurrent alteration of several biological pathways in nonsmall cell lung cancer cells

    PubMed Central

    Ju, Z.; Kapoor, M.; Newton, K; Cheon, K.; Ramaswamy, A.; Lotan, R.; Strong, L. C.; Koo, J. S.

    2006-01-01

    To identify the molecular changes that occur in non-small cell lung carcinoma (NSCLC), we compared the gene expression profile of the NCI-H292 (H292) NSCLC cell line with that of normal human tracheobronchial epithelial (NHTBE) cells. The NHTBE cells were grown in a three-dimensional organotypic culture system that permits maintenance of the normal pseudostratified mucociliary phenotype characteristic of bronchial epithelium in vivo. Microarray analysis using the Affymetrix oligonucleotide chip U95Av2 revealed that 1,683 genes showed a > 1.5-fold change in expression in the H292 cell line relative to the NHTBE cells. Specifically, 418 genes were downregulated and 1,265 were upregulated in the H292 cells. The expression data for selected genes were validated in several different NSCLC cell lines using quantitative real-time PCR and Western analysis. Further analysis of the differentially expressed genes indicated that WNT responses, apoptosis, cell cycle regulation and cell proliferation were significantly altered in the H292 cells. Functional analysis using fluorescence-activated cell sorting confirmed concurrent changes in the activity of these pathways in the H292 line. These findings show that (1) NSCLC cells display deregulation of the WNT, apoptosis, proliferation and cell cycle pathways, as has been found in many other types of cancer cells, and (2) that organotypically cultured NHTBE cells can be used as a reference to identify genes and pathways that are differentially expressed in tumor cells derived from bronchogenic epithelium. PMID:16049682

  3. Review of diagnostic and therapeutic endoscopic retrograde cholangiopancreatography using several endoscopic methods in patients with surgically altered gastrointestinal anatomy

    PubMed Central

    Shimatani, Masaaki; Takaoka, Makoto; Tokuhara, Mitsuo; Miyoshi, Hideaki; Ikeura, Tsukasa; Okazaki, Kazuichi

    2015-01-01

    The endoscopic approach for biliary diseases in patients with surgically altered gastrointestinal anatomy (SAGA) had been generally deemed impractical. However, it was radically made feasible by the introduction of double balloon endoscopy (DBE) that was originally developed for diagnosis and treatments for small-bowel diseases. Followed by the subsequent development of single-balloon endoscopy (SBE) and spiral endoscopy (SE), interventions using several endoscopes for biliary disease in patients with SAGA widely gained an acceptance as a new modality. Many studies have been made on this new technique. Yet, some problems are to be solved. For instance, the mutual unavailability among devices due to different working lengths and channels, and unestablished standardization of procedural techniques can be raised. Additionally, in an attempt to standardize endoscopic procedures, it is important to evaluate biliary cannulating methods by case with existence of papilla or not. A full comprehension of the features of respective scope types is also required. However there are not many papers written as a review. In our manuscript, we would like to evaluate and make a review of the present status of diagnostic and therapeutic endoscopic retrograde cholangiopancreatography applying DBE, SBE and SE for biliary diseases in patients with SAGA for establishment of these modalities as a new technology and further improvement of the scopes and devices. PMID:26078830

  4. Hemodynamic monitoring devices: putting it all together.

    PubMed

    Naik, Bhiken I; Durieux, Marcel E

    2014-12-01

    Perioperative hemodynamic optimization of the high-risk surgical patient is associated with reduced postoperative morbidity and mortality. The hemodynamic parameters to be optimized (using goal-directed algorithms) encompass preload, contractility, afterload, volume responsiveness, and end-organ perfusion. Current hemodynamic monitors facilitate multi-modal monitoring of these macro-hemodynamic targets. This review focuses on the variety of invasive, minimally invasive, and noninvasive hemodynamic monitors available to the clinician. PMID:25480776

  5. Expression of Extracellular Matrix-Remodeling Proteins Is Altered in Vaginal Tissue of Premenopausal Women With Severe Pelvic Organ Prolapse

    PubMed Central

    Alarab, May; Kufaishi, Hala; Lye, Stephen; Drutz, Harold

    2014-01-01

    Aim: The molecular etiology of pelvic organ prolapse (POP) is complex and not well understood. We compared the expression/activity of extracellular matrix (ECM)-processing (procollagen I N-proteinase/ a disintegrin and metalloproteinase with thrombospondin motifs [ADAMTS]-2,-3,-14) and ECM-degrading (matrix metalloproteinase [MMP]-1, -2, -7, -8, -9, -12) enzymes and their natural tissue inhibitors (tissue inhibitors of metalloproteinase [TIMP]-1,-2,-3,-4) in vaginal tissues from premenopausal women with advanced POP (POP-Q stage ≥ 3) and asymptomatic controls (POP-Q = 0). Study Design: We sampled the anterior vaginal wall of 36 premenopausal women (17 patients with POP and 19 controls) undergoing total hysterectomy. Exclusion criteria include steroid therapy, malignancy, previous pelvic surgery, and connective tissue diseases. Total RNAs and proteins were quantified by real-time polymerase chain reaction, immunoblotting, and Luminex assay; MMPs activity was analyzed by zymography and tissue localization by immunohistochemistry. Results: The MMP-2 gelatinase activity as well as expression of 58-kDa isoform of ADAMTS-2 was upregulated in patients with POP, irrespective of menstrual phase status, secretory or proliferative, when compared to controls (P < .05). The TIMP-1-4 gene and TIMP-1 protein expression were significantly (P < .05) reduced, whereas protein expression of MMP-12 (pro and active forms) was significantly increased in vaginal biopsies of patients with POP in the proliferative phase of the menstrual cycle compared to corresponding controls. Analyses of MMP-12, TIMP-1, and ADAMTS-2 tissue immunostaining indicate similar localization in the vaginal specimens from control and patients with POP. Conclusion: Expression of ECM-remodeling proteins is altered in the vagina of premenopausal patients with severe POP. We speculate that dysregulation of MMP/TIMP complexes and ADAMTS-2 proteins may cause connective tissue defects, which result in weakened vaginal

  6. Hemodynamic and metabolic effects of cerebral revascularization.

    PubMed

    Leblanc, R; Tyler, J L; Mohr, G; Meyer, E; Diksic, M; Yamamoto, L; Taylor, L; Gauthier, S; Hakim, A

    1987-04-01

    Pre- and postoperative positron emission tomography (PET) was performed in six patients undergoing extracranial to intracranial bypass procedures for the treatment of symptomatic extracranial carotid occlusion. The six patients were all men, aged 52 to 68 years. Their symptoms included transient ischemic attacks (five cases), amaurosis fugax (two cases), and completed stroke with good recovery (one case). Positron emission tomography was performed within 4 weeks prior to surgery and between 3 to 6 months postoperatively, using oxygen-15-labeled CO, O2, and CO2 and fluorine-18-labeled fluorodeoxyglucose. Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rates for oxygen and glucose (CMRO2 and CMRGlu), and the oxygen extraction fraction (OEF) were measured in both hemispheres. Preoperatively, compared to five elderly control subjects, patients had increased CBV, a decreased CBF/CBV ratio, and decreased CMRO2, indicating reduced cerebral perfusion pressure and depressed oxygen metabolism. The CBF was decreased in only one patient who had bilateral carotid occlusions; the OEF, CMRGlu, and CMRO2/CMRGlu and CMRGlu/CBF ratios were not significantly different from control measurements. All bypasses were patent and all patients were asymptomatic following surgery. Postoperative PET revealed decreased CBV and an increased CBF/CBV ratio, indicating improved hemodynamic function and oxygen hypometabolism. This was associated with increased CMRO2 in two patients in whom the postoperative OEF was also increased. The CMRGlu and CMRGlu/CBF ratio were increased in five patients. Changes in CBF and the CMRO2/CMRGlu ratio were variable. One patient with preoperative progressive mental deterioration, documented by serial neuropsychological testing and decreasing CBF and CMRO2, had improved postoperative CBF and CMRO2 concomitant with improved neuropsychological functioning. It is concluded that symptomatic carotid occlusion is associated with altered

  7. Rapid Cerebral Hemodynamic Modulation during Set Shifting: Evidence of Time-Locked Associations with Cognitive Control in Females

    ERIC Educational Resources Information Center

    Schuepbach, Daniel; Huizinga, Mariette; Duschek, Stefan; Grimm, Simone; Boeker, Heinz; Hell, Daniel

    2009-01-01

    Set shifting provokes specific alterations of cerebral hemodynamics in basal cerebral arteries. However, no gender differences have been reported. In the following functional transcranial Doppler study, we introduced cerebral hemodynamic modulation to the aspects of set shifting during Wisconsin Card Sorting Test (WCST). Twenty-one subjects…

  8. Cue-Reactive Altered State of Consciousness Mediates the Relationship Between Problem-Gambling Severity and Cue-Reactive Urge in Poker-Machine Gamblers.

    PubMed

    Tricker, Christopher; Rock, Adam J; Clark, Gavin I

    2016-06-01

    In order to enhance our understanding of the nature of poker-machine problem-gambling, a community sample of 37 poker-machine gamblers (M age = 32 years, M PGSI = 5; PGSI = Problem Gambling Severity Index) were assessed for urge to gamble (responses on a visual analogue scale) and altered state of consciousness (assessed by the Altered State of Awareness dimension of the Phenomenology of Consciousness Inventory) at baseline, after a neutral cue, and after a gambling cue. It was found that (a) problem-gambling severity (PGSI score) predicted increase in urge (from neutral cue to gambling cue, controlling for baseline; sr (2) = .19, p = .006) and increase in altered state of consciousness (from neutral cue to gambling cue, controlling for baseline; sr (2) = .57, p < .001), and (b) increase in altered state of consciousness (from neutral cue to gambling cue) mediated the relationship between problem-gambling severity and increase in urge (from neutral cue to gambling cue; κ(2) = .40, 99 % CI [.08, .71]). These findings suggest that cue-reactive altered state of consciousness is an important component of cue-reactive urge in poker-machine problem-gamblers. PMID:26026986

  9. Proteomic analysis of Plasmodium falciparum induced alterations in humans from different endemic regions of India to decipher malaria pathogenesis and identify surrogate markers of severity.

    PubMed

    Ray, Sandipan; Kumar, Vipin; Bhave, Amruta; Singh, Vaidhvi; Gogtay, Nithya J; Thatte, Urmila M; Talukdar, Arunansu; Kochar, Sanjay K; Patankar, Swati; Srivastava, Sanjeeva

    2015-09-01

    India significantly contributes to the global malaria burden and has the largest population in the world at risk of malaria. This study aims to analyze alterations in the human serum proteome as a consequence of non-severe and severe infections by the malaria parasite Plasmodium falciparum to identify markers related to disease severity and to obtain mechanistic insights about disease pathogenesis and host immune responses. In discovery phase of the study, a comprehensive quantitative proteomic analysis was performed using gel-based (2D-DIGE) and gel-free (iTRAQ) techniques on two independent mass spectrometry platforms (ESI-Q-TOF and Q-Exactive mass spectrometry), and selected targets were validated by ELISA. Proteins showing altered serum abundance in falciparum malaria patients revealed the modulation of different physiological pathways including chemokine and cytokine signaling, IL-12 signaling and production in macrophages, complement cascades, blood coagulation, and protein ubiquitination pathways. Some muscle related and cytoskeletal proteins such as titin and galectin-3-binding protein were found to be up-regulated in severe malaria patients. Hemoglobin levels and platelet counts were also found to be drastically lower in severe malaria patients. Identified proteins including serum amyloid A, C-reactive protein, apolipoprotein E and haptoglobin, which exhibited sequential alterations in their serum abundance in different severity levels of malaria, could serve as potential predictive markers for disease severity. To the best of our information, we report here the first comprehensive analysis describing the serum proteomic alterations observed in severe P. falciparum infected patients from different malaria endemic regions of India. This article is part of a Special Issue entitled: Proteomics in India. PMID:25982387

  10. Lagrangian postprocessing of computational hemodynamics

    PubMed Central

    Shadden, Shawn C.; Arzani, Amirhossein

    2014-01-01

    Recent advances in imaging, modeling and computing have rapidly expanded our capabilities to model hemodynamics in the large vessels (heart, arteries and veins). This data encodes a wealth of information that is often under-utilized. Modeling (and measuring) blood flow in the large vessels typically amounts to solving for the time-varying velocity field in a region of interest. Flow in the heart and larger arteries is often complex, and velocity field data provides a starting point for investigating the hemodynamics. This data can be used to perform Lagrangian particle tracking, and other Lagrangian-based postprocessing. As described herein, Lagrangian methods are necessary to understand inherently transient hemodynamic conditions from the fluid mechanics perspective, and to properly understand the biomechanical factors that lead to acute and gradual changes of vascular function and health. The goal of the present paper is to review Lagrangian methods that have been used in post-processing velocity data of cardiovascular flows. PMID:25059889

  11. Hemodynamic Influences on Abdominal Aortic Aneurysm Disease: Application of Biomechanics to Aneurysm Pathophysiology

    PubMed Central

    Dua, Monica M.; Dalman, Ronald L.

    2010-01-01

    “Atherosclerotic” abdominal aortic aneurysms (AAAs) occur with the greatest frequency in the distal aorta. The unique hemodynamic environment of this area predisposes it to site-specific degenerative changes. In this review, we summarize the differential hemodynamic influences present along the length of the abdominal aorta, and demonstrate how alterations in aortic flow and wall shear stress modify AAA progression in experimental models. Improved understanding of aortic hemodynamic risk profiles provides an opportunity to modify patient activity patterns to minimize risk of aneurysmal degeneration. PMID:20347049

  12. Hemodynamic studies of the legs under weightlessness

    NASA Technical Reports Server (NTRS)

    Thornton, W. E.; Hoffler, G. W.

    1974-01-01

    Following exposure to weightlessness, alterations in the return of blood from the legs play a crucial role in orthostatic tolerance and may be an important factor in work tolerance. To investigate some of the hemodynamic mechansism involved, an experiment was performed on the Skylab 3 and Skylab 4 missions to study arterial blood flow, venous compliance, and muscle pumping of blood. Skylab 4 results indicated that the most likely cause of increased blood flow was an increase in cardiac output secondary to increased central venous pressure caused by blood redistribution. Changes in venous compliance are thought to be primarily changes in somatic musculature which is postulated to primarily determine venous compliance of the legs. This was also thought to be demonstrated by the changes in muscle pumping. It is thought that these compliance changes, when taken with the decreased blood volume; provide a basis for the changes seen in orthostatic tolerance, work capacity and lower body negative pressure response.

  13. Pulmonary hemodynamics in children living at high altitudes.

    PubMed

    Penaloza, Dante; Sime, Francisco; Ruiz, Luis

    2008-01-01

    There are numerous publications on altitude-related diseases in adults. In addition, an International Consensus Statement published in 2001 deals with altitude-related illnesses occurring in lowland children who travel to high altitudes. However, despite the millions of children living permanently at high altitudes around the world, there are few publications on altitude-related diseases and pulmonary hemodynamics in this pediatric population. In this paper, we review the published literature on this subject. First, the pulmonary hemodynamics of healthy children (newborns, infants, children, and adolescents) residing at altitudes above 4000 m are summarized. Asymptomatic pulmonary hypertension, which slowly declines with increasing age, is found in these children. This is followed by a discussion of the functional closure of ductus arteriosus, which is delayed at high altitude. Then, the high prevalence of patent ductus arteriosus (PDA) in highland children and the pulmonary hemodynamics in these patients are described. Next, the pulmonary hemodynamics in highland children who suffer high altitude pulmonary edema (HAPE) after a short stay at lower levels is discussed, and the possible reasons for susceptibility to reentry HAPE in this pediatric population are postulated. The pulmonary hemodynamics in children with subacute mountain sickness (SMS) are then described. Moderate to severe pulmonary hypertension is a common finding in all these altitude-related diseases. Finally, the management of these clinical conditions is outlined. PMID:18800956

  14. Hemodynamic physiology and thermoregulation in liposuction.

    PubMed

    Kenkel, Jeffrey M; Lipschitz, Avron H; Luby, Maureen; Kallmeyer, Ian; Sorokin, Evan; Appelt, Eric; Rohrich, Rod J; Brown, Spencer A

    2004-08-01

    Little is known about the physiology of large-volume liposuction. Patients are exposed to prolonged procedures, general anesthesia, fluid shifts, and infusion of high doses of epinephrine and lidocaine. Consequently, the authors examined the thermoregulatory and cardiovascular responses to liposuction by assessing multiple physiologic factors. The aims of their study were to serially determine hemodynamic parameters perioperatively, to quantify perioperative and postoperative plasma epinephrine levels, and to chronologically document fluctuations in core body temperature. Five female volunteers with American Society of Anesthesiologists' physical status I and II underwent moderate- to large-volume liposuction. Heart rate, blood pressure, mean pulmonary arterial pressure, cardiac index, and central venous pressure were monitored. Serum epinephrine levels and core body temperature were assessed perioperatively. The hemodynamic responses to liposuction were characterized by an increase in cardiac index (57 percent), heart rate (47 percent), and mean pulmonary arterial pressure (44 percent) (p < 0.05). Central venous pressure was not significantly altered. Maximum epinephrine levels were observed 5 to 6 hours after induction. Significant correlations between cardiac index and epinephrine concentrations were shown intraoperatively (r = 0.75). All patients developed intraoperative low body temperatures (mean 35.5 degrees C). An overall enhanced cardiac function was observed in patients subsequent to large-volume liposuction. The etiology of the altered cardiac parameters was multifactorial but may have been attributable in part to the administration of epinephrine, which counters the effects of general anesthesia and operative hypothermia. Additional explanations for raised cardiac output may be hemodilution or emergence from general anesthesia. Elevated mean pulmonary arterial pressure may be a result of subclinical fat embolism demonstrated in previous porcine studies

  15. Review: hemodynamic response to carbon monoxide

    SciTech Connect

    Penney, D.G.

    1988-04-01

    Historically, and at present, carbon monoxide is a major gaseous poison responsible for widespread morbidity and mortality. From threshold to maximal nonlethal levels, a variety of cardiovascular changes occur, both immediately and in the long term, whose homeostatic function it is to renormalize tissue oxygen delivery. However, notwithstanding numerous studies over the past century, the literature remains equivocal regarding the hemodynamic responses in animals and humans, although CO hypoxia is clearly different in several respects from hypoxic hypoxia. Factors complicating interpretation of experimental findings include species, CO dose level and rate, route of CO delivery, duration, level of exertion, state of consciousness, and anesthetic agent used. Augmented cardiac output usually observed with moderate COHb may be compromised in more sever poisoning for the same reasons, such that regional or global ischemia result. The hypotension usually seen in most animal studies is thought to be a primary cause of CNS damage resulting from acute CO poisoning, yet the exact mechanism(s) remains unproven in both animals and humans, as does the way in which CO produces hypotension. This review briefly summarizes the literature relevant to the short- and long-term hemodynamic responses reported in animals and humans. It concludes by presenting an overview using data from a single species in which the most complete work has been done to date.

  16. Systemic and Ocular Hemodynamic Risk Factors in Glaucoma

    PubMed Central

    Choi, Jaewan; Kook, Michael S.

    2015-01-01

    Primary open angle glaucoma (POAG) is a multifactorial disease characterized by progressive retinal ganglion cell death and visual field loss. It is known that alterations in intraocular pressure (IOP), blood pressure (BP), and ocular perfusion pressure (OPP) can play a significant role in the pathogenesis of the disease. Impaired autoregulatory capacity of ocular blood vessels may render tissues vulnerable to OPP changes and potentially harmful tissue ischemia-reperfusion damage. Vascular risk factors should be considered more important in a subgroup of patients with POAG, and especially in patients with normal tension glaucoma (NTG) with evidence of unphysiological BP response. For example, reduction of BP during the nighttime has an influence on OPP, and increased circadian OPP fluctuation, which might stand for unstable ocular blood flow, has been found to be the consistent risk factor for NTG development and progression. Central visual field may be affected more severely than peripheral visual field in NTG patients with higher 24-hour fluctuation of OPP. This review will discuss the current understanding of allegedly major systemic and ocular hemodynamic risk factors for glaucoma including systemic hypertension, arterial stiffness, antihypertensive medication, exaggerated nocturnal hypotension, OPP, and autonomic dysregulation. PMID:26557650

  17. Alterations of T helper lymphocyte subpopulations in sepsis, severe sepsis, and septic shock: a prospective observational study.

    PubMed

    Li, Jia; Li, Ming; Su, Longxiang; Wang, Huijuan; Xiao, Kun; Deng, Jie; Jia, Yanhong; Han, Gencheng; Xie, Lixin

    2015-01-01

    Circulating lymphocyte number was significantly decreased in patients with sepsis. However, it remains unknown which severity phase (sepsis, severe sepsis, and septic shock) does it develop and what happen on each subpopulation. Eight patients with differing severities of sepsis (31 sepses, 33 severe sepses, and 16 septic shocks) were enrolled. Quantitative real-time polymerase chain reaction (RT-PCR) of Th1, Th2, and Th17; regulatory T (Treg) cell-specific transcription factor T-bet; GATA-3; RORgammat (RORγt); forkhead box P3 (FOXP3); and IL-17 mRNA were performed, and the enzyme-linked immunosorbent assay (ELISA) was used to detect serum interferon (IFN)-γ, IL-4, and IL-10. In this study, the Th1, Th2, Treg transcription factors, and related cytokines IFN-γ, IL-4, and IL-10 levels of sepsis and severe sepsis patients in peripheral blood were significantly higher than those of the normal controls. Except for IL-17, the T-bet, GATA-3, and IFN-γ levels of septic shock patients were lower than those of sepsis patients. We also observed that the proportions of Th17/Treg in the sepsis and septic shock groups were inversed. From the above, the inflammatory response especially the adaptive immune response is still activated in sepsis and severe sepsis, but significant immunosuppression was developed in septic shock. In addition, the proportion of Th17/Treg inversed may be associated with the illness aggravation of patients with sepsis. PMID:25403265

  18. Overexpression of Dyrk1A Is Implicated in Several Cognitive, Electrophysiological and Neuromorphological Alterations Found in a Mouse Model of Down Syndrome

    PubMed Central

    García-Cerro, Susana; Martínez, Paula; Vidal, Verónica; Corrales, Andrea; Flórez, Jesús; Vidal, Rebeca; Rueda, Noemí; Arbonés, María L.; Martínez-Cué, Carmen

    2014-01-01

    Down syndrome (DS) phenotypes result from the overexpression of several dosage-sensitive genes. The DYRK1A (dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A) gene, which has been implicated in the behavioral and neuronal alterations that are characteristic of DS, plays a role in neuronal progenitor proliferation, neuronal differentiation and long-term potentiation (LTP) mechanisms that contribute to the cognitive deficits found in DS. The purpose of this study was to evaluate the effect of Dyrk1A overexpression on the behavioral and cognitive alterations in the Ts65Dn (TS) mouse model, which is the most commonly utilized mouse model of DS, as well as on several neuromorphological and electrophysiological properties proposed to underlie these deficits. In this study, we analyzed the phenotypic differences in the progeny obtained from crosses of TS females and heterozygous Dyrk1A (+/−) male mice. Our results revealed that normalization of the Dyrk1A copy number in TS mice improved working and reference memory based on the Morris water maze and contextual conditioning based on the fear conditioning test and rescued hippocampal LTP. Concomitant with these functional improvements, normalization of the Dyrk1A expression level in TS mice restored the proliferation and differentiation of hippocampal cells in the adult dentate gyrus (DG) and the density of GABAergic and glutamatergic synapse markers in the molecular layer of the hippocampus. However, normalization of the Dyrk1A gene dosage did not affect other structural (e.g., the density of mature hippocampal granule cells, the DG volume and the subgranular zone area) or behavioral (i.e., hyperactivity/attention) alterations found in the TS mouse. These results suggest that Dyrk1A overexpression is involved in some of the cognitive, electrophysiological and neuromorphological alterations, but not in the structural alterations found in DS, and suggest that pharmacological strategies targeting this gene

  19. Overexpression of Dyrk1A is implicated in several cognitive, electrophysiological and neuromorphological alterations found in a mouse model of Down syndrome.

    PubMed

    García-Cerro, Susana; Martínez, Paula; Vidal, Verónica; Corrales, Andrea; Flórez, Jesús; Vidal, Rebeca; Rueda, Noemí; Arbonés, María L; Martínez-Cué, Carmen

    2014-01-01

    Down syndrome (DS) phenotypes result from the overexpression of several dosage-sensitive genes. The DYRK1A (dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A) gene, which has been implicated in the behavioral and neuronal alterations that are characteristic of DS, plays a role in neuronal progenitor proliferation, neuronal differentiation and long-term potentiation (LTP) mechanisms that contribute to the cognitive deficits found in DS. The purpose of this study was to evaluate the effect of Dyrk1A overexpression on the behavioral and cognitive alterations in the Ts65Dn (TS) mouse model, which is the most commonly utilized mouse model of DS, as well as on several neuromorphological and electrophysiological properties proposed to underlie these deficits. In this study, we analyzed the phenotypic differences in the progeny obtained from crosses of TS females and heterozygous Dyrk1A (+/-) male mice. Our results revealed that normalization of the Dyrk1A copy number in TS mice improved working and reference memory based on the Morris water maze and contextual conditioning based on the fear conditioning test and rescued hippocampal LTP. Concomitant with these functional improvements, normalization of the Dyrk1A expression level in TS mice restored the proliferation and differentiation of hippocampal cells in the adult dentate gyrus (DG) and the density of GABAergic and glutamatergic synapse markers in the molecular layer of the hippocampus. However, normalization of the Dyrk1A gene dosage did not affect other structural (e.g., the density of mature hippocampal granule cells, the DG volume and the subgranular zone area) or behavioral (i.e., hyperactivity/attention) alterations found in the TS mouse. These results suggest that Dyrk1A overexpression is involved in some of the cognitive, electrophysiological and neuromorphological alterations, but not in the structural alterations found in DS, and suggest that pharmacological strategies targeting this gene may

  20. Tacrolimus does not alter the production of several cytokines and antimicrobial peptide in Malassezia furfur-infected-keratinocytes.

    PubMed

    Balato, Anna; Paoletti, Iole; De Gregorio, Vincenza; Cantelli, Mariateresa; Ayala, Fabio; Donnarumma, Giovanna

    2014-03-01

    Topical immunosuppressant therapy is widely used in the treatment of inflammatory skin diseases, such as atopic dermatitis and psoriasis. Besides its beneficial therapeutic effects, application of topical anti-inflammatory drugs may render the epidermis more vulnerable to invading pathogens by suppressing innate immune responses in keratinocytes (KCs). Cytokines, chemokines and antimicrobial peptides (AMPs) produced by epithelial cells enable them to participate in innate and acquired immune responses. The aim of the present work was to study the influence of tacrolimus (FK506) on KCs infected with Malassezia furfur (M. furfur), evaluating the expression of pro-inflammatory cytokines IL-1α and IL-6, chemokine IL-8, anti-inflammatory cytokines transforming growth factor beta1 (TGF-β1) and IL-10 and AMP β-defensin-2. Human KCs were obtained from surgical specimens of normal adult skin. The expression of mRNAs in KCs: FK506-treated, FK506-treated and M. furfur-infected as well as only M. furfur-infected was quantified by real-time quantitative polymerase chain reaction. Next, the production of the AMP β-defensin-2 and of the above-mentioned pro-inflammatory and anti-inflammatory cytokines was evaluated using enzyme-linked immunosorbent assay. In this study, FK506 did not alter cytokine and AMP production by KCs; this led us to hypothesise that it may not enhance the risk of mycotic skin infections. PMID:24512536

  1. Hemodynamics of Mechanical Circulatory Support.

    PubMed

    Burkhoff, Daniel; Sayer, Gabriel; Doshi, Darshan; Uriel, Nir

    2015-12-15

    An increasing number of devices can provide mechanical circulatory support (MCS) to patients with acute hemodynamic compromise and chronic end-stage heart failure. These devices work by different pumping mechanisms, have various flow capacities, are inserted by different techniques, and have different sites from which blood is withdrawn and returned to the body. These factors result in different primary hemodynamic effects and secondary responses of the body. However, these are not generally taken into account when choosing a device for a particular patient or while managing a patient undergoing MCS. In this review, we discuss fundamental principles of cardiac, vascular, and pump mechanics and illustrate how they provide a broad foundation for understanding the complex interactions between the heart, vasculature, and device, and how they may help guide future research to improve patient outcomes. PMID:26670067

  2. Hemodynamic and tubular changes induced by contrast media.

    PubMed

    Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

  3. Hemodynamic and Tubular Changes Induced by Contrast Media

    PubMed Central

    Caiazza, Antonella; Russo, Luigi; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

  4. A Model System for Mapping Vascular Responses to Complex Hemodynamics at Arterial Bifurcations In Vivo

    PubMed Central

    Meng, Hui; Swartz, Daniel D.; Wang, Zhijie; Hoi, Yiemeng; Kolega, John; Metaxa, Eleni M.; Szymanski, Michael P.; Yamamoto, Junichi; Sauvageau, Eric; Levy, Elad I.

    2009-01-01

    Objective Cerebral aneurysms are preferentially located at arterial bifurcation apices with complex hemodynamics. To understand disease mechanisms associated with aneurysm initiation, we attempted to establish a causal relationship between local hemodynamics and vascular responses. Methods Arterial bifurcations were surgically created from native common carotid arteries in two dogs, angiographically imaged 2 weeks and 2 months later, and then excised. We characterized local morphological changes in response to specifically manipulated hemodynamics. Computational fluid dynamics simulations were performed on the in vivo images and results mapped onto histological images. Results Local flow conditions, such as high wall shear stress and high wall shear stress gradient, were found to be associated with vascular changes, including an intimal pad in the flow impingement region and a “groove” bearing the characteristics of an early aneurysm. Conclusion This novel method of histohemodynamic micromapping reveals a direct correlation between an altered hemodynamic microenvironment and vascular responses consistent with aneurysm development. PMID:17143243

  5. Hemodynamics of Cerebral Aneurysms: Computational Analyses of Aneurysm Progress and Treatment

    PubMed Central

    Jeong, Woowon; Rhee, Kyehan

    2012-01-01

    The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment. PMID:22454695

  6. Altered Levels of Zinc and N-methyl-D-aspartic Acid Receptor Underlying Multiple Organ Dysfunctions After Severe Trauma

    PubMed Central

    Wang, Guanghuan; Yu, Xiaojun; Wang, Dian; Xu, Xiaohu; Chen, Guang; Jiang, Xuewu

    2015-01-01

    Background Severe trauma can cause secondary multiple organ dysfunction syndrome (MODS) and death. Oxidative stress and/or excitatory neurotoxicity are considered as the final common pathway in nerve cell injuries. Zinc is the cofactor of the redox enzyme, and the effect of the excitatory neurotoxicity is related to N-methyl-D-aspartic acid receptor (NMDAR). Material/Methods We investigated the levels of zinc and brainstem NMDAR in a rabbit model of severe trauma. Zinc and serum biochemical profiles were determined. Immunohistochemistry was used to detect brainstem N-methyl-D-aspartic acid receptor 1 (NR1), N-methyl-D-aspartic acid receptor 2A (NR2A), and N-methyl-D-aspartic acid receptor 2B (NR2B) expression. Results Brain and brainstem Zn levels increased at 12 h, but serum Zn decreased dramatically after the trauma. NR1 in the brainstem dorsal regions increased at 6 h after injury and then decreased. NR2A in the dorsal regions decreased to a plateau at 12 h after trauma. The levels of NR2B were lowest in the death group in the brainstem. Serum zinc was positively correlated with NR2A and 2B and negatively correlated with zinc in the brain. Correlations were also found between the brainstem NR2A and that of the dorsal brainstem, as well as between brainstem NR2A and changes in NR2B. There was a negative correlation between zinc and NR2A. Conclusions Severe trauma led to an acute reduction of zinc enhancing oxidative stress and the changes of NMDAR causing the neurotoxicity of the nerve cells. This may be a mechanism for the occurrence of MODS or death after trauma. PMID:26335029

  7. Cerebral venous hemodynamic abnormalities in episodic and chronic migraine

    PubMed Central

    Petolicchio, Barbara; Viganò, Alessandro; di Biase, Lazzaro; Tatulli, Doriana; Toscano, Massimiliano; Vicenzini, Edoardo; Passarelli, Francesco; Di Piero, Vittorio

    2016-01-01

    Summary Alterations of cerebral venous drainage have been demonstrated in chronic migraine (CM), suggesting that cerebral venous hemodynamic abnormalities (CVHAs) play a role in this condition. The aim of the present study was to look for a correlation between CM and CVHAs. We recruited 33 subjects suffering from CM with or without analgesic overuse, 29 episodic migraine (EM) patients with or without aura, and 21 healthy subjects as controls (HCs). CVHAs were evaluated by transcranial and extracranial echo-color Doppler evaluation of five venous hemodynamic parameters. CVHAs were significantly more frequent in the CM and EM patients than in the HCs. In the migraine patients, CVHAs were not correlated with clinical features. The significantly greater frequency of CVHAs observed in the migraineurs may reflect a possible relationship between migraine and these abnormalities. Prospective longitudinal studies are needed to investigate whether CVHAs have a role in the processes of migraine chronification. PMID:27358220

  8. The hippocampi of children with chromosome 22q11.2 deletion syndrome have localized anterior alterations that predict severity of anxiety

    PubMed Central

    Scott, Julia A.; Goodrich-Hunsaker, Naomi; Kalish, Kristopher; Lee, Aaron; Hunsaker, Michael R.; Schumann, Cynthia M.; Carmichael, Owen T.; Simon, Tony J.

    2016-01-01

    Background Individuals with 22q11.2 deletion syndrome (22q11.2DS) have an elevated risk for schizophrenia, which increases with history of childhood anxiety. Altered hippocampal morphology is a common neuroanatomical feature of 22q11.2DS and idiopathic schizophrenia. Relating hippocampal structure in children with 22q11.2DS to anxiety and impaired cognitive ability could lead to hippocampus-based characterization of psychosis-proneness in this at-risk population. Methods We measured hippocampal volume using a semiautomated approach on MRIs collected from typically developing children and children with 22q11.2DS. We then analyzed hippocampal morphology with Localized Components Analysis. We tested the modulating roles of diagnostic group, hippocampal volume, sex and age on local hippocampal shape components. Lastly, volume and shape components were tested as covariates of IQ and anxiety. Results We included 48 typically developing children and 69 children with 22q11.2DS in our study. Hippocampal volume was reduced bilaterally in children with 22q11.2DS, and these children showed greater variation in the shape of the anterior hippocampus than typically developing children. Children with 22q11.2DS had greater inward deformation of the anterior hippocampus than typically developing children. Greater inward deformation of the anterior hippocampus was associated with greater severity of anxiety, specifically fear of physical injury, within the 22q11.2DS group. Limitations Shape alterations are not specific to hippocampal subfields. Conclusion Alterations in the structure of the anterior hippocampus likely affect function and may impact limbic circuitry. We suggest these alterations potentially contribute to anxiety symptoms in individuals with 22q11.2DS through modulatory pathways. Altered hippocampal morphology may be uniquely linked to anxiety risk factors for schizophrenia, which could be a powerful neuroanatomical marker of schizophrenia risk and hence protection

  9. Pharmacological Modulation of Hemodynamics in Adult Zebrafish In Vivo

    PubMed Central

    Brönnimann, Daniel; Dellenbach, Christian; Saveljic, Igor; Rieger, Michael; Rohr, Stephan; Filipovic, Nenad; Djonov, Valentin

    2016-01-01

    Introduction Hemodynamic parameters in zebrafish receive increasing attention because of their important role in cardiovascular processes such as atherosclerosis, hematopoiesis, sprouting and intussusceptive angiogenesis. To study underlying mechanisms, the precise modulation of parameters like blood flow velocity or shear stress is centrally important. Questions related to blood flow have been addressed in the past in either embryonic or ex vivo-zebrafish models but little information is available for adult animals. Here we describe a pharmacological approach to modulate cardiac and hemodynamic parameters in adult zebrafish in vivo. Materials and Methods Adult zebrafish were paralyzed and orally perfused with salt water. The drugs isoprenaline and sodium nitroprusside were directly applied with the perfusate, thus closely resembling the preferred method for drug delivery in zebrafish, namely within the water. Drug effects on the heart and on blood flow in the submental vein were studied using electrocardiograms, in vivo-microscopy and mathematical flow simulations. Results Under control conditions, heart rate, blood flow velocity and shear stress varied less than ± 5%. Maximal chronotropic effects of isoprenaline were achieved at a concentration of 50 μmol/L, where it increased the heart rate by 22.6 ± 1.3% (n = 4; p < 0.0001). Blood flow velocity and shear stress in the submental vein were not significantly increased. Sodium nitroprusside at 1 mmol/L did not alter the heart rate but increased blood flow velocity by 110.46 ± 19.64% (p = 0.01) and shear stress by 117.96 ± 23.65% (n = 9; p = 0.03). Discussion In this study, we demonstrate that cardiac and hemodynamic parameters in adult zebrafish can be efficiently modulated by isoprenaline and sodium nitroprusside. Together with the suitability of the zebrafish for in vivo-microscopy and genetic modifications, the methodology described permits studying biological processes that are dependent on hemodynamic

  10. Hemodynamic Correlates of Cognition in Human Infants

    PubMed Central

    Aslin, Richard N.; Shukla, Mohinish; Emberson, Lauren L.

    2015-01-01

    Over the past 20 years, the field of cognitive neuroscience has relied heavily on hemodynamic measures of blood oxygenation in local regions of the brain to make inferences about underlying cognitive processes. These same functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) techniques have recently been adapted for use with human infants. We review the advantages and disadvantages of these two neuroimaging methods for studies of infant cognition, with a particular emphasis on their technical limitations and the linking hypotheses that are used to draw conclusions from correlational data. In addition to summarizing key findings in several domains of infant cognition, we highlight the prospects of improving the quality of fNIRS data from infants to address in a more sophisticated way how cognitive development is mediated by changes in underlying neural mechanisms. PMID:25251480

  11. Spatiotemporal hemodynamic response functions derived from physiology.

    PubMed

    Aquino, K M; Robinson, P A; Drysdale, P M

    2014-04-21

    Probing neural activity with functional magnetic resonance imaging (fMRI) relies upon understanding the hemodynamic response to changes in neural activity. Although existing studies have extensively characterized the temporal hemodynamic response, less is understood about the spatial and spatiotemporal hemodynamic responses. This study systematically characterizes the spatiotemporal response by deriving the hemodynamic response due to a short localized neural drive, i.e., the spatiotemporal hemodynamic response function (stHRF) from a physiological model of hemodynamics based on a poroelastic model of cortical tissue. In this study, the model's boundary conditions are clarified and a resulting nonlinear hemodynamic wave equation is derived. From this wave equation, damped linear hemodynamic waves are predicted from the stHRF. The main features of these waves depend on two physiological parameters: wave propagation speed, which depends on mean cortical stiffness, and damping which depends on effective viscosity. Some of these predictions were applied and validated in a companion study (Aquino et al., 2012). The advantages of having such a theory for the stHRF include improving the interpretation of spatiotemporal dynamics in fMRI data; improving estimates of neural activity with fMRI spatiotemporal deconvolution; and enabling wave interactions between hemodynamic waves to be predicted and exploited to improve the signal to noise ratio of fMRI. PMID:24398024

  12. Transmediastinal and Transcardiac Gunshot Wound with Hemodynamic Stability

    PubMed Central

    Al-Lal, Yusef Mohamed; de Tomás Palacios, Jorge; Amunategui Prats, Iñaki; Turégano Fuentes, Fernando

    2014-01-01

    Cardiac injuries caused by knives and firearms are slightly increasing in our environment. We report the case of a 43-year-old male patient with a transmediastinal gunshot wound (TGSW) and a through-and-through cardiac wound who was hemodynamically stable upon his admission. He had an entrance wound below the left clavicle, with no exit wound, and decreased breath sounds in the right hemithorax. Chest X-ray showed the bullet in the right hemithorax and large right hemothorax. The ultrasound revealed pericardial effusion, and a chest tube produced 1500 cc. of blood, but he remained hemodynamically stable. Considering these findings, a median sternotomy was carried out, the through-and-through cardiac wounds were suture-repaired, lung laceration was sutured, and a pacemaker was placed in the right ventricle. The patient had uneventful recovery and was discharged home on the twelfth postoperative day. The management and prognosis of these patients are determined by the hemodynamic situation upon arrival to the Emergency Department (ED), as well as a prompt surgical repair if needed. Patients with a TGSW have been divided into three groups according to the SBP: group I, with SBP >100 mmHg; group II, with SBP 60–100 mmHg; and group III, with SBP <60 mmHg. The diagnostic workup and management should be tailored accordingly, and several series have confirmed high chances of success with conservative management when these patients are hemodynamically stable. PMID:25197606

  13. Antisense Suppression of the Small Chloroplast Protein CP12 in Tobacco Alters Carbon Partitioning and Severely Restricts Growth1[W

    PubMed Central

    Howard, Thomas P.; Fryer, Michael J.; Singh, Prashant; Metodiev, Metodi; Lytovchenko, Anna; Obata, Toshihiro; Fernie, Alisdair R.; Kruger, Nicholas J.; Quick, W. Paul; Lloyd, Julie C.; Raines, Christine A.

    2011-01-01

    The thioredoxin-regulated chloroplast protein CP12 forms a multienzyme complex with the Calvin-Benson cycle enzymes phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). PRK and GAPDH are inactivated when present in this complex, a process shown in vitro to be dependent upon oxidized CP12. The importance of CP12 in vivo in higher plants, however, has not been investigated. Here, antisense suppression of CP12 in tobacco (Nicotiana tabacum) was observed to impact on NAD-induced PRK and GAPDH complex formation but had little effect on enzyme activity. Additionally, only minor changes in photosynthetic carbon fixation were observed. Despite this, antisense plants displayed changes in growth rates and morphology, including dwarfism and reduced apical dominance. The hypothesis that CP12 is essential to separate oxidative pentose phosphate pathway activity from Calvin-Benson cycle activity, as proposed in cyanobacteria, was tested. No evidence was found to support this role in tobacco. Evidence was seen, however, for a restriction to malate valve capacity, with decreases in NADP-malate dehydrogenase activity (but not protein levels) and pyridine nucleotide content. Antisense repression of CP12 also led to significant changes in carbon partitioning, with increased carbon allocation to the cell wall and the organic acids malate and fumarate and decreased allocation to starch and soluble carbohydrates. Severe decreases were also seen in 2-oxoglutarate content, a key indicator of cellular carbon sufficiency. The data presented here indicate that in tobacco, CP12 has a role in redox-mediated regulation of carbon partitioning from the chloroplast and provides strong in vivo evidence that CP12 is required for normal growth and development in plants. PMID:21865489

  14. Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict.

    PubMed

    Lutz, Juergen; Thon, Niklas; Stahl, Robert; Lummel, Nina; Tonn, Joerg-Christian; Linn, Jennifer; Mehrkens, Jan-Hinnerk

    2016-03-01

    OBJECT In this prospective study diffusion tensor imaging (DTI) was used to evaluate the influence of clinical and anatomical parameters on structural alterations within the fifth cranial nerve in patients with trigeminal neuralgia (TN) due to neurovascular compression. METHODS Overall, 81 patients (40 men and 41 women; mean age 60 ± 5 years) with typical TN were included who underwent microsurgical decompression. Preoperative 3.0-T high-resolution MRI and DTI were analyzed in a blinded fashion. The respective fractional anisotropy (FA) and apparent diffusion coefficient values were compared with the clinical, imaging, and intraoperative data. This study was approved by the institutional review board, and written informed consent was obtained from all patients. RESULTS DTI analyses revealed significantly lower FA values within the vulnerable zone of the affected trigeminal nerve compared with the contralateral side (p = 0.05). The DTI analyses also included 3 patients without clear evidence of neurovascular conflict on preoperative MRI. No differences were seen between arterial and venous compression. Lower FA values were found 5 months after symptom onset; however, no correlation was found with the duration of symptoms or severity of compression. CONCLUSIONS DTI analysis allows the quantification of structural alterations, even in those patients without any discernible neurovascular contact on MRI. Moreover, our findings support the hypothesis that both the arteries and veins can cause structural alterations that lead to TN. These aspects can be useful for making treatment decisions. PMID:26406792

  15. Comparing hemodynamic models with DCM

    PubMed Central

    Stephan, Klaas Enno; Weiskopf, Nikolaus; Drysdale, Peter M.; Robinson, Peter A.; Friston, Karl J.

    2007-01-01

    The classical model of blood oxygen level-dependent (BOLD) responses by Buxton et al. [Buxton, R.B., Wong, E.C., Frank, L.R., 1998. Dynamics of blood flow and oxygenation changes during brain activation: the Balloon model. Magn. Reson. Med. 39, 855–864] has been very important in providing a biophysically plausible framework for explaining different aspects of hemodynamic responses. It also plays an important role in the hemodynamic forward model for dynamic causal modeling (DCM) of fMRI data. A recent study by Obata et al. [Obata, T., Liu, T.T., Miller, K.L., Luh, W.M., Wong, E.C., Frank, L.R., Buxton, R.B., 2004. Discrepancies between BOLD and flow dynamics in primary and supplementary motor areas: application of the Balloon model to the interpretation of BOLD transients. NeuroImage 21, 144–153] linearized the BOLD signal equation and suggested a revised form for the model coefficients. In this paper, we show that the classical and revised models are special cases of a generalized model. The BOLD signal equation of this generalized model can be reduced to that of the classical Buxton model by simplifying the coefficients or can be linearized to give the Obata model. Given the importance of hemodynamic models for investigating BOLD responses and analyses of effective connectivity with DCM, the question arises which formulation is the best model for empirically measured BOLD responses. In this article, we address this question by embedding different variants of the BOLD signal equation in a well-established DCM of functional interactions among visual areas. This allows us to compare the ensuing models using Bayesian model selection. Our model comparison approach had a factorial structure, comparing eight different hemodynamic models based on (i) classical vs. revised forms for the coefficients, (ii) linear vs. non-linear output equations, and (iii) fixed vs. free parameters, ε, for region-specific ratios of intra- and extravascular signals. Using fMRI data

  16. MAOA Alters the Effects of Heavy Drinking and Childhood Physical Abuse on Risk for Severe Impulsive Acts of Violence Among Alcoholic Violent Offenders

    PubMed Central

    Tikkanen, Roope; Ducci, Francesca; Goldman, David; Holi, Matti; Lindberg, Nina; Tiihonen, Jari; Virkkunen, Matti

    2011-01-01

    Background A polymorphism in the promoter region of the monoamine oxidase A gene (MAOA) has been shown to alter the effect of persistent drinking and childhood maltreatment on the risk for violent and antisocial behaviors. These findings indicate that MAOA could contribute to inter-individual differences in stress resiliency. Methods Recidivism in severe violent crimes was assessed after 8 years of nonincarcerated follow-up in a male sample of 174 impulsive Finnish alcoholic violent offenders, the majority of whom exhibited antisocial (ASPD) or borderline personality disorder (BPD) or both. We examined whether MAOA genotype alters the effects of heavy drinking and childhood physical abuse (CPA) on the risk for committing impulsive recidivistic violent crimes. Results Logistic regression analyses showed that both heavy drinking and CPA were significant independent predictors of recidivism in violent behavior (OR 5.2, p = 0.004 and OR 5.3, p = 0.003) among offenders having the high MAOA activity genotype (MAOA-H), but these predictors showed no effect among offenders carrying the low MAOA activity genotype (MAOA-L). Conclusion Carriers of the MAOA-H allele have a high risk to commit severe recidivistic impulsive violent crimes after exposure to heavy drinking and CPA. PMID:20201935

  17. Hemodynamic instability following intentional nadolol overdose.

    PubMed

    Ehgartner, G R; Zelinka, M A

    1988-04-01

    Hemodynamic compromise developed following intentional overdose with nadolol in a 57-year-old woman. Nadolol is a nonselective beta-adrenergic blocking agent. Intravenous infusion of glucagon hydrochloride was effective in restoring hemodynamic stability after intravenous fluid loading and catecholamine infusions had failed. To our knowledge, this is the first reported case of nadolol overdose. PMID:3355299

  18. Hemodynamics of focal choroidal excavations.

    PubMed

    Soma, Ryoko; Moriyama, Muka; Ohno-Matsui, Kyoko

    2015-04-01

    The purpose of this study was to investigate the hemodynamics of focal choroidal excavations (FCEs). Four eyes of four patients with a FCE were studied. Indocyanine green angiography (ICGA), laser speckle flowgraphy (LSFG), optical coherence tomography (OCT), and multi-focal electroretinography (mfERG) were performed to investigate the choroidal hemodynamics and the morphological and functional changes. The mean depth of the FCE determined by OCT was 222.5 ± 49.5 μm with a range of 164-272 μm. In one case, subretinal fluid was observed in the excavation, and in three cases, subretinal fluid was not observed. ICGA showed hypofluorescence, and laser flowgraphy (LSFG) showed decreased choroidal blood flow at the excavation in all cases. Three cases were symptomatic, and the amplitudes of the mfERGs were reduced. FCEs cause a decrease of choroidal blood flow. In three of four cases, the mfERGs were depressed over the FCEs leading to symptoms. PMID:25626897

  19. Early Altered Resting-State Functional Connectivity Predicts the Severity of Post-Traumatic Stress Disorder Symptoms in Acutely Traumatized Subjects

    PubMed Central

    Qin, Ling-di; Wan, Jie-qing; Sun, Ya-wen; Su, Shan-shan; Ding, Wei-na; Xu, Jian-rong

    2012-01-01

    The goal of this study was to investigate the relationship between resting-state functional connectivity and the severity of post-traumatic stress disorder (PTSD) symptoms in 15 people who developed PTSD following recent trauma. Fifteen participants who experienced acute traumatic events underwent a 7.3-min resting functional magnetic resonance imaging scan within 2 days post-event. All the patients were diagnosed with PTSD within 1 to 6 months after trauma. Brain areas in which activity was correlated with that of the posterior cingulate cortex (PCC) were assessed. To assess the relationship between the severity of PTSD symptoms and PCC connectivity, contrast images representing areas positively correlated with the PCC were correlated with the subject’s Clinician-Administered PTSD Scale scores (CAPS) when they were diagnosed. Furthermore, the PCC, medial prefrontal cortex and bilateral amygdala were selected to assess the correlation of the strength of functional connectivity with the CAPS. Resting state connectivity with the PCC was negatively correlated with CAPS scores in the left superior temporal gyrus and right hippocampus/amygdala. Furthermore, the strength of connectivity between the PCC and bilateral amygdala, and even between the bilateral amygdala could predict the severity of PTSD symptoms later. These results suggest that early altered resting-state functional connectivity of the PCC with the left superior temporal gyrus, right hippocampus and amygdala could predict the severity of the disease and may be a major risk factor that predisposes patients to develop PTSD. PMID:23056477

  20. Vestibular stimulation leads to distinct hemodynamic patterning

    NASA Technical Reports Server (NTRS)

    Kerman, I. A.; Emanuel, B. A.; Yates, B. J.

    2000-01-01

    Previous studies demonstrated that responses of a particular sympathetic nerve to vestibular stimulation depend on the type of tissue the nerve innervates as well as its anatomic location. In the present study, we sought to determine whether such precise patterning of vestibulosympathetic reflexes could lead to specific hemodynamic alterations in response to vestibular afferent activation. We simultaneously measured changes in systemic blood pressure and blood flow (with the use of Doppler flowmetry) to the hindlimb (femoral artery), forelimb (brachial artery), and kidney (renal artery) in chloralose-urethane-anesthetized, baroreceptor-denervated cats. Electrical vestibular stimulation led to depressor responses, 8 +/- 2 mmHg (mean +/- SE) in magnitude, that were accompanied by decreases in femoral vasoconstriction (23 +/- 4% decrease in vascular resistance or 36 +/- 7% increase in vascular conductance) and increases in brachial vascular tone (resistance increase of 10 +/- 6% and conductance decrease of 11 +/- 4%). Relatively small changes (<5%) in renal vascular tone were observed. In contrast, electrical stimulation of muscle and cutaneous afferents produced pressor responses (20 +/- 6 mmHg) that were accompanied by vasoconstriction in all three beds. These data suggest that vestibular inputs lead to a complex pattern of cardiovascular changes that is distinct from that which occurs in response to activation of other types of somatic afferents.

  1. The utility of novel non-invasive technologies for remote hemodynamic monitoring in chronic heart failure.

    PubMed

    Mabote, Thato; Wong, Kenneth; Cleland, John G F

    2014-08-01

    Monitoring a patient's hemodynamic status may be a revolutionary way to aid a 'health maintenance' strategy in which the physician strives to therapeutically keep the patient in an ideal hemodynamic range. Currently, home telemonitoring employs a 'crisis-prevention' approach. This strategy is still based on easily acquired measures such as heart rate, weight and blood pressure--measurements that are useful to help implement guideline-directed therapy but provide little information about impending decompensation or the risk of hospitalisation. Current systems provide limited information to personalize and adapt medication therapy for heart failure. Several innovative technologies that can remotely monitor estimates of cardiovascular hemodynamics, such as cardiac index, systemic vascular resistance, augmentation index and added heart sounds may enable earlier detection of heart failure decompensation. This editorial presents an overview of the innovative technologies that are available for non-invasive hemodynamic monitoring and maybe adapted for home telemonitoring for chronic heart failure. PMID:25026973

  2. A simulation model to study the role of the extracranial venous drainage pathways in intracranial hemodynamics.

    PubMed

    Gadda, G; Taibi, A; Sisini, F; Gambaccini, M; Sethi, S K; Utriainen, D; Haacke, E M; Zamboni, P; Ursino, M

    2015-08-01

    Alterations in the extracranial venous circulation due to posture changes, and/or extracranial venous obstructions in patients with vascular diseases, can have important implications on cerebral hemodynamics. A hemodynamic model for the study of cerebral venous outflow was developed to investigate the correlations between extracranial blood redistributions and changes in the intracranial environment. Flow data obtained with both magnetic resonance (MR) and Echo-Color Doppler (ECD) technique are used to validate the model. The very good agreement between simulated supine and upright flows and experimental results means that the model can correctly reproduce the main factors affecting the extracranial venous circulation. PMID:26738101

  3. Artifact reduction in long-term monitoring of cerebral hemodynamics using near-infrared spectroscopy

    PubMed Central

    Vinette, Sarah A.; Dunn, Jeff F.; Slone, Edward; Federico, Paolo

    2015-01-01

    Abstract. Near-infrared spectroscopy (NIRS) is a noninvasive neuroimaging technique used to assess cerebral hemodynamics. Its portability, ease of use, and relatively low operational cost lend itself well to the long-term monitoring of hemodynamic changes, such as those in epilepsy, where events are unpredictable. Long-term monitoring is associated with challenges including alterations in behaviors and motion that can result in artifacts. Five patients with epilepsy were assessed for interictal hemodynamic changes and alterations in behavior or motion. Based on this work, visual inspection was used to identify NIRS artifacts during a period of interest, specifically prior to seizures, in four patients. A motion artifact reduction algorithm (MARA, also known as the spline interpolation method) was tested on these data. Alterations in the NIRS measurements often occurred simultaneously with changes in motion and behavior. Occasionally, sharp shift artifacts were observed in the data. When artifacts appeared as sustained baseline shifts in the data, MARA reduced the standard deviation of the data and the appearance improved. We discussed motion and artifacts as challenges associated with long-term monitoring of cerebral hemodynamics in patients with epilepsy and our group’s approach to circumvent these challenges and improve the quality of the data collected. PMID:26158008

  4. Hemodynamic Segmentation of Brain Perfusion Images with Delay and Dispersion Effects Using an Expectation-Maximization Algorithm

    PubMed Central

    Lu, Chia-Feng; Guo, Wan-Yuo; Chang, Feng-Chi; Huang, Shang-Ran; Chou, Yen-Chun; Wu, Yu-Te

    2013-01-01

    Automatic identification of various perfusion compartments from dynamic susceptibility contrast magnetic resonance brain images can assist in clinical diagnosis and treatment of cerebrovascular diseases. The principle of segmentation methods was based on the clustering of bolus transit-time profiles to discern areas of different tissues. However, the cerebrovascular diseases may result in a delayed and dispersed local perfusion and therefore alter the hemodynamic signal profiles. Assessing the accuracy of the segmentation technique under delayed/dispersed circumstance is critical to accurately evaluate the severity of the vascular disease. In this study, we improved the segmentation method of expectation-maximization algorithm by using the results of hierarchical clustering on whitened perfusion data as initial parameters for a mixture of multivariate Gaussians model. In addition, Monte Carlo simulations were conducted to evaluate the performance of proposed method under different levels of delay, dispersion, and noise of signal profiles in tissue segmentation. The proposed method was used to classify brain tissue types using perfusion data from five normal participants, a patient with unilateral stenosis of the internal carotid artery, and a patient with moyamoya disease. Our results showed that the normal, delayed or dispersed hemodynamics can be well differentiated for patients, and therefore the local arterial input function for impaired tissues can be recognized to minimize the error when estimating the cerebral blood flow. Furthermore, the tissue in the risk of infarct and the tissue with or without the complementary blood supply from the communicating arteries can be identified. PMID:23894386

  5. Age-correlated changes in cerebral hemodynamics assessed by near-infrared spectroscopy.

    PubMed

    Safonova, Larisa P; Michalos, Antonios; Wolf, Ursula; Wolf, Martin; Hueber, Dennis M; Choi, Jee H; Gupta, Rajarsi; Polzonetti, Chiara; Mantulin, William W; Gratton, Enrico

    2004-01-01

    Cerebral hemodynamic responses due to normal aging may interfere with hormonal changes, drug therapy, diseases, life style, and other factors. Age-correlated alterations in cerebral vasculature and autoregulatory mechanisms are the subject of interest in many studies. Near-infrared spectroscopy (NIRS) is widely used for monitoring cerebral hemodynamics and oxygenation changes at the level of small vessels. We believe that the compensatory ability of cerebral arterioles under hypoxic conditions and the dilatatory ability of cerebral vessels due to vasomotion may decline with normal aging. To test this hypothesis we used frequency-domain NIRS to measure changes in cerebral tissue oxygenation and oxy- and deoxy-hemoglobin concentrations caused by hypoxia during breath holding. We also assessed cerebral vasomotion during profound relaxation. Thirty seven healthy volunteers, 12 females and 25 males, ranging from 22 to 56 years of age (mean age 35 +/- 11 years) participated in the study. We observed age-correlated changes in the cerebral hemodynamics of normal subjects: diminished cerebral hemodynamic response to hypoxia due to breath holding in middle-aged subjects (38-56 years) and reduced amplitude of cerebral hemodynamic changes due to vasomotion during rest. Snoring related changes in cerebral hemodynamics did not allow us to observe the effect of age in a group of snorers. The prolonged supine position influenced measured changes due to hypoxia. In this investigation NIRS methodology allowed detection of age-correlated changes in cerebral oxygenation and hemodynamics. Other variables, such as snoring or posture impacted the observations in our group of healthy volunteers. PMID:15381340

  6. Simultaneous hemodynamic and echocardiographic changes during abdominal gas insufflation.

    PubMed

    Myre, K; Buanes, T; Smith, G; Stokland, O

    1997-10-01

    The purpose of this study was to investigate cardiovascular changes during CO2 pneumoperitoneum. We performed simultaneous hemodynamic recordings and transesophageal echocardiographic measurements of possible alterations in cardiac dimensions. Seven patients scheduled for elective laparoscopic cholecystectomy were investigated. With an intraabdominal pressure of 15 mm Hg, mean arterial pressure increased from 75 to 93 mm Hg (p < 0.05). Despite the increase in pulmonary capillary wedge pressure (PCWP) from 10 (9.5-12) to 17 (16-19.9) mm Hg (p < 0.05), left ventricular end-diastolic area index (EDAI) did not change significantly. The cardiac index remained unchanged. Thus abdominal gas insufflation substantially alters the PCWP/EDAI relation. During pneumoperitoneum, left ventricular filling pressure, estimated by PCWP, cannot be used as an indicator of left ventricular dilation. PMID:9348623

  7. Dysregulation of oxygen hemodynamic responses to synaptic train stimulation in a rat hippocampal model of subarachnoid hemorrhage.

    PubMed

    Galeffi, Francesca; Degan, Simone; Britz, Gavin; Turner, Dennis A

    2016-04-01

    We investigated microvascular reactivity to synaptic train stimulation after induction of subarachnoid hemorrhage in adult rats, analyzing tissue oxygen levels [pO2] in intact hippocampus. In control rats, hippocampal pO2averaged 11.4 mm Hg whereas hemodynamic responses averaged 13.1 mm Hg (to a 25 s train). After subarachnoid hemorrhage (at 2 days), we recorded a dramatic elevation in baseline pO2in the hippocampus (to 68.4 mm Hg) accompanied by inverted pO2responses to synaptic train stimulation (-9.46 mm Hg). These significant changes in baseline hippocampal pO2and inverted pO2responses after subarachnoid hemorrhage indicate severe alterations of neurovascular coupling and neuronal viability. PMID:26721394

  8. Effects of the inlet conditions and blood models on accurate prediction of hemodynamics in the stented coronary arteries

    NASA Astrophysics Data System (ADS)

    Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

    2015-05-01

    Hemodynamics altered by stent implantation is well-known to be closely related to in-stent restenosis. Computational fluid dynamics (CFD) method has been used to investigate the hemodynamics in stented arteries in detail and help to analyze the performances of stents. In this study, blood models with Newtonian or non-Newtonian properties were numerically investigated for the hemodynamics at steady or pulsatile inlet conditions respectively employing CFD based on the finite volume method. The results showed that the blood model with non-Newtonian property decreased the area of low wall shear stress (WSS) compared with the blood model with Newtonian property and the magnitude of WSS varied with the magnitude and waveform of the inlet velocity. The study indicates that the inlet conditions and blood models are all important for accurately predicting the hemodynamics. This will be beneficial to estimate the performances of stents and also help clinicians to select the proper stents for the patients.

  9. Perioperative cerebral hemodynamics and oxygen metabolism in neonates with single-ventricle physiology

    PubMed Central

    Dehaes, Mathieu; Cheng, Henry H.; Buckley, Erin M.; Lin, Pei-Yi; Ferradal, Silvina; Williams, Kathryn; Vyas, Rutvi; Hagan, Katherine; Wigmore, Daniel; McDavitt, Erica; Soul, Janet S.; Franceschini, Maria Angela; Newburger, Jane W.; Ellen Grant, P.

    2015-01-01

    Congenital heart disease (CHD) patients are at risk for neurodevelopmental delay. The etiology of these delays is unclear, but abnormal prenatal cerebral maturation and postoperative hemodynamic instability likely play a role. A better understanding of these factors is needed to improve neurodevelopmental outcome. In this study, we used bedside frequency-domain near infrared spectroscopy (FDNIRS) and diffuse correlation spectroscopy (DCS) to assess cerebral hemodynamics and oxygen metabolism in neonates with single-ventricle (SV) CHD undergoing surgery and compared them to controls. Our goals were 1) to compare cerebral hemodynamics between unanesthetized SV and healthy neonates, and 2) to determine if FDNIRS-DCS could detect alterations in cerebral hemodynamics beyond cerebral hemoglobin oxygen saturation (SO2). Eleven SV neonates were recruited and compared to 13 controls. Preoperatively, SV patients showed decreased cerebral blood flow (CBFi), cerebral oxygen metabolism (CMRO2i) and SO2; and increased oxygen extraction fraction (OEF) compared to controls. Compared to preoperative values, unstable postoperative SV patients had decreased CMRO2i and CBFi, which returned to baseline when stable. However, SO2 showed no difference between unstable and stable states. Preoperative SV neonates are flow-limited and show signs of impaired cerebral development compared to controls. FDNIRS-DCS shows potential to improve assessment of cerebral development and postoperative hemodynamics compared to SO2 alone. PMID:26713191

  10. Saturation thresholds of evoked neural and hemodynamic responses in awake and asleep rats

    NASA Astrophysics Data System (ADS)

    Schei, Jennifer L.; Van Nortwick, Amy S.; Meighan, Peter C.; Rector, David M.

    2011-03-01

    Neural activation generates a hemodynamic response to the localized region replenishing nutrients to the area. Changes in vigilance state have been shown to alter the vascular response where the vascular response is muted during wake compared to quiet sleep. We tested the saturation thresholds of the neurovascular response in the auditory cortex during wake and sleep by chronically implanting rats with an EEG electrode, a light emitting diode (LED, 600 nm), and photodiode to simultaneously measure evoked response potentials (ERPs) and evoked hemodynamic responses. We stimulated the cortex with a single speaker click delivered at random intervals 2-13 s at varied stimulus intensities ranging from 45-80 dB. To further test the potential for activity related saturation, we sleep deprived animals for 2, 4, or 6 hours and recorded evoked responses during the first hour recovery period. With increasing stimulus intensity, integrated ERPs and evoked hemodynamic responses increased; however the hemodynamic response approached saturation limits at a lower stimulus intensity than the ERP. With longer periods of sleep deprivation, the integrated ERPs did not change but evoked hemodynamic responses decreased. There may be physical limits in cortical blood delivery and vascular compliance, and with extended periods of neural activity during wake, vessels may approach these limits.

  11. Venous hemodynamic changes in lower limb venous disease: the UIP consensus according to scientific evidence.

    PubMed

    Lee, Byung B; Nicolaides, Andrew N; Myers, Kenneth; Meissner, Mark; Kalodiki, Evi; Allegra, Claudio; Antignani, Pier L; Bækgaard, Niels; Beach, Kirk; Belcaro, Giovanni; Black, Stephen; Blomgren, Lena; Bouskela, Eliete; Cappelli, Massimo; Caprini, Joseph; Carpentier, Patrick; Cavezzi, Attilio; Chastanet, Sylvain; Christenson, Jan T; Christopoulos, Demetris; Clarke, Heather; Davies, Alun; Demaeseneer, Marianne; Eklöf, Bo; Ermini, Stefano; Fernández, Fidel; Franceschi, Claude; Gasparis, Antonios; Geroulakos, George; Sergio, Gianesini; Giannoukas, Athanasios; Gloviczki, Peter; Huang, Ying; Ibegbuna, Veronica; Kakkos, Stavros K; Kistner, Robert; Kölbel, Tilo; Kurstjens, Ralph L; Labropoulos, Nicos; Laredo, James; Lattimer, Christopher R; Lugli, Marzia; Lurie, Fedor; Maleti, Oscar; Markovic, Jovan; Mendoza, Erika; Monedero, Javier L; Moneta, Gregory; Moore, Hayley; Morrison, Nick; Mosti, Giovanni; Nelzén, Olle; Obermayer, Alfred; Ogawa, Tomohiro; Parsi, Kurosh; Partsch, Hugo; Passariello, Fausto; Perrin, Michel L; Pittaluga, Paul; Raju, Seshadri; Ricci, Stefano; Rosales, Antonio; Scuderi, Angelo; Slagsvold, Carl E; Thurin, Anders; Urbanek, Tomasz; M VAN Rij, Andre; Vasquez, Michael; Wittens, Cees H; Zamboni, Paolo; Zimmet, Steven; Ezpeleta, Santiago Z

    2016-06-01

    thrombosis indicating their pathophysiological and clinical significance. Chapter 3 describes the hemodynamic changes that occur in different classes of chronic venous disease and their relation to the anatomic extent of disease in the macrocirculation and microcirculation. The next four chapters (Chapters 4-7) describe the hemodynamic changes resulting from treatmen by compression using different materials, intermittent compression devices, pharmacological agents and finally surgical or endovenous ablation. Chapter 8 discusses the unique hemodynamic features associated with alternative treatment techniques used by the CHIVA and ASVAL. Chapter 9 describes the hemodynamic effects following treatment to relieve pelvic reflux and obstruction. Finally, Chapter 10 demonstrates that contrary to general belief there is a moderate to good correlation between certain hemodynamic measurements and clinical severity of chronic venous disease. The authors believe that this document will be a timely asset to both clinicians and researchers alike. It is directed towards surgeons and physicians who are anxious to incorporate the conclusions of research into their daily practice. It is also directed to postgraduate trainees, vascular technologists and bioengineers, particularly to help them understand the hemodynamic background to pathophysiology, investigations and treatment of patients with venous disorders. Hopefully it will be a platform for those who would like to embark on new research in the field of venous disease. PMID:27013029

  12. Hemodynamics driven cardiac valve morphogenesis.

    PubMed

    Steed, Emily; Boselli, Francesco; Vermot, Julien

    2016-07-01

    Mechanical forces are instrumental to cardiovascular development and physiology. The heart beats approximately 2.6 billion times in a human lifetime and heart valves ensure that these contractions result in an efficient, unidirectional flow of the blood. Composed of endocardial cells (EdCs) and extracellular matrix (ECM), cardiac valves are among the most mechanically challenged structures of the body both during and after their development. Understanding how hemodynamic forces modulate cardiovascular function and morphogenesis is key to unraveling the relationship between normal and pathological cardiovascular development and physiology. Most valve diseases have their origins in embryogenesis, either as signs of abnormal developmental processes or the aberrant re-expression of fetal gene programs normally quiescent in adulthood. Here we review recent discoveries in the mechanobiology of cardiac valve development and introduce the latest technologies being developed in the zebrafish, including live cell imaging and optical technologies, as well as modeling approaches that are currently transforming this field. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel. PMID:26608609

  13. Hemodynamics of a hydrodynamic injection

    PubMed Central

    Kanefuji, Tsutomu; Yokoo, Takeshi; Suda, Takeshi; Abe, Hiroyuki; Kamimura, Kenya; Liu, Dexi

    2014-01-01

    The hemodynamics during a hydrodynamic injection were evaluated using cone beam computed tomography (CBCT) and fluoroscopic imaging. The impacts of hydrodynamic (5 seconds) and slow (60 seconds) injections into the tail veins of mice were compared using 9% body weight of a phase-contrast medium. Hydrodynamically injected solution traveled to the heart and drew back to the hepatic veins (HV), which led to liver expansion and a trace amount of spillover into the portal vein (PV). The liver volumes peaked at 165.6 ± 13.3% and 165.5 ± 11.9% of the original liver volumes in the hydrodynamic and slow injections, respectively. Judging by the intensity of the CBCT images at the PV, HV, right atrium, liver parenchyma (LP), and the inferior vena cava (IVC) distal to the HV conjunction, the slow injection resulted in the higher intensity at PV than at LP. In contrast, a significantly higher intensity was observed in LP after hydrodynamic injection in comparison with that of PV, suggesting that the liver took up the iodine from the blood flow. These results suggest that the enlargement speed of the liver, rather than the expanded volume, primarily determines the efficiency of hydrodynamic delivery to the liver. PMID:26015971

  14. Hemodynamic Shear Stress and Endothelial Dysfunction in Hemodialysis Access

    PubMed Central

    Fitts, Michelle K.; Pike, Daniel B.; Anderson, Kasey; Shiu, Yan-Ting

    2014-01-01

    Surgically-created blood conduits used for chronic hemodialysis, including native arteriovenous fistulas (AVFs) and synthetic AV grafts (AVGs), are the lifeline for kidney failure patients. Unfortunately, each has its own limitations: AVFs often fail to mature to become useful for dialysis and AVGs often fail due to stenosis as a result of neointimal hyperplasia, which preferentially forms at the graft-venous anastomosis. No clinical therapies are currently available to significantly promote AVF maturation or prevent neointimal hyperplasia in AVGs. Central to devising strategies to solve these problems is a complete mechanistic understanding of the pathophysiological processes. The pathology of arteriovenous access problems is likely multi-factorial. This review focuses on the roles of fluid-wall shear stress (WSS) and endothelial cells (ECs). In arteriovenous access, shunting of arterial blood flow directly into the vein drastically alters the hemodynamics in the vein. These hemodynamic changes are likely major contributors to non-maturation of an AVF vein and/or formation of neointimal hyperplasia at the venous anastomosis of an AVG. ECs separate blood from other vascular wall cells and also influence the phenotype of these other cells. In arteriovenous access, the responses of ECs to aberrant WSS may subsequently lead to AVF non-maturation and/or AVG stenosis. This review provides an overview of the methods for characterizing blood flow and calculating WSS in arteriovenous access and discusses EC responses to arteriovenous hemodynamics. This review also discusses the role of WSS in the pathology of arteriovenous access, as well as confounding factors that modulate the impact of WSS. PMID:25309636

  15. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers

    PubMed Central

    Son, Taeyoon; Wang, Benquan; Thapa, Damber; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

    2016-01-01

    Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis. PMID:27570706

  16. Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers.

    PubMed

    Son, Taeyoon; Wang, Benquan; Thapa, Damber; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

    2016-08-01

    Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis. PMID:27570706

  17. Hormones and Hemodynamics in Pregnancy

    PubMed Central

    Tkachenko, Oleksandra; Shchekochikhin, Dmitry; Schrier, Robert W.

    2014-01-01

    Context: Normal pregnancy is associated with sodium and water retention, which results in plasma volume expansion prior to placental implantation. The explanation offered for these events is that pregnancy ‘resets’ both volume and osmoreceptors. Evidence Acquisition: The mechanisms for such an enigmatic ‘resetting’ in pregnancy have not previously been explained. However, recent human pregnancy studies have demonstrated that the earliest hemodynamic change in pregnancy is primary systemic arterial vasodilation. This arterial underfilling is associated with a secondary increase in cardiac output and activation of the neurohumoral axis, including stimulation of the renin-angiotensin-aldosterone, sympathetic, and non-osmotic vasopressin systems. Resistance to the pressor effects of angiotensin and sympathetic stimulation in pregnancy is compatible with an increase in endothelial nitric oxide synthase activity. Results: In contrast to the sodium and water retention which occur secondary to the primary arterial vasodilation in cirrhosis, glomerular filtration and renal blood flow are significantly increased in normal pregnancy. A possible explanation for this difference in arterial vasodilation states is that relaxin, an arterial vasodilator which increases during pregnancy, has a potent effect on both systemic and renal circulation. Endothelial damage in pregnancy is pivotal in the pathogenesis of preeclampsia in pregnancy. Conclusions: Against a background of the primary arterial vasodilation hypothesis, it is obvious that reversal of the systemic vasodilatation in pregnancy, without subsequent activation of the renin-angiotensin-aldosterone system (78), will evoke a reversal of all the links in the chain of events in normal pregnancy adaptation, thus, it may cause preeclampsia. Namely, a decrease of renal vasodilation will decrease glomerular filtration rate. PMID:24803942

  18. Hemodynamic response patterns to mental stress: diagnostic and therapeutic implications.

    PubMed

    Rüddel, H; Langewitz, W; Schächinger, H; Schmieder, R; Schulte, W

    1988-08-01

    Stress has been identified as contributing to the development of cardiovascular disease. The pathophysiologic link between stress and disease still remains unclear. Because experimental stress testing in the laboratory permits the examination of the underlying mechanism for stress-induced blood pressure, analyses of cardiovascular reactivity during emotional stress could be of particular clinical importance. The analyses of pooled data during the past 6 years (n = 298, age from 20 to 60 years, normotensive subjects as well as patients with borderline and mild essential hypertension) reveal that stress-induced changes in stroke volume and especially in total peripheral resistance are crucial parameters to analyze the hemodynamic stress response. However, neither those simple nor complex response patterns such as "hot reactor" describe clinically distinct subgroups of persons. When physiologic testing was repeated in hypertensive patients after effective long-term antihypertensive therapy with clonidine, oxprenolol, nitrendipine, or enalapril, no attenuation of the stress-induced increase in blood pressure was found in any of these groups. However, heart rate reactivity and stress-induced changes in total peripheral resistance were altered significantly by oxprenolol and nitrendipine. The beta-adrenoceptor blocker decreased heart rate reactivity and increased reactivity of peripheral resistance; the calcium antagonist decreased stress-induced changes in peripheral resistance and increased the heart rate response. The centrally acting sympatholytic regimen and the angiotensin-converting enzyme inhibitor had no impact on the hemodynamic response pattern during emotional challenge. PMID:3394640

  19. Severe sepsis during pregnancy.

    PubMed

    Pacheco, Luis D; Saade, George R; Hankins, Gary D V

    2014-12-01

    Severe sepsis is a major cause of mortality among critically ill patients. Early recognition accompanied by early initiation of broad-spectrum antibiotics with source control and fluid resuscitation improves outcomes. Hemodynamic resuscitation starts with fluid therapy followed by vasopressors if necessary. Cases refractory to first-line vasopressors (norepinephrine) will require second-line vasopressors (epinephrine or vasopressin) and low-dose steroid therapy. Resuscitation goals should include optimization of central venous oxygenation and serum lactate. PMID:25286297

  20. Combined Effects of Flow Diverting Strategies and Parent Artery Curvature on Aneurysmal Hemodynamics: A CFD Study

    PubMed Central

    Yu, Ying; Lv, Nan; Wang, Shengzhang; Karmonik, Christof; Liu, Jian-Min; Huang, Qinghai

    2015-01-01

    Purpose Flow diverters (FD) are increasingly being considered for treating large or giant wide-neck aneurysms. Clinical outcome is highly variable and depends on the type of aneurysm, the flow diverting device and treatment strategies. The objective of this study was to analyze the effect of different flow diverting strategies together with parent artery curvature variations on altering intra-aneurysmal hemodynamics. Methods Four ideal intracranial aneurysm models with different parent artery curvature were constructed. Computational fluid dynamics (CFD) simulations of the hemodynamics before and after applying five types of flow diverting strategies (single FD, single FD with 5% and 10% packing density of coils, two FDs with 25% and 50% overlapping rate) were performed. Changes in pressure, wall shear stress (WSS), relative residence time (RRT), inflow velocity and inflow volume rate were calculated and compared. Results Each flow diverting strategy resulted in enhancement of RRT and reduction of normalized mean WSS, inflow volume rate and inflow velocity in various levels. Among them, 50% overlapped FD induced most effective hemodynamic changes in RRT and inflow volume rate. The mean pressure only slightly decreased after treatment. Regardless of the kind of implantation of FD, the mean pressure, inflow volume rate and inflow velocity increased and the RRT decreased as the curvature of the parent artery increased. Conclusions Of all flow diverting strategies, overlapping FDs induced most favorable hemodynamic changes. Hemodynamics alterations post treatment were substantially influenced by parent artery curvature. Our results indicate the need of an individualized flow diverting strategy that is tailored for a specific aneurysm. PMID:26398847

  1. Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jenkins, Michael W.; Peterson, Lindsy; Gu, Shi; Gargesha, Madhusudhana; Wilson, David L.; Watanabe, Michiko; Rollins, Andrew M.

    2010-11-01

    Hemodynamics is thought to play a major role in heart development, yet tools to quantitatively assess hemodynamics in the embryo are sorely lacking. The especially challenging analysis of hemodynamics in the early embryo requires new technology. Small changes in blood flow could indicate when anomalies are initiated even before structural changes can be detected. Furthermore, small changes in the early embryo that affect blood flow could lead to profound abnormalities at later stages. We present a demonstration of 4-D Doppler optical coherence tomography (OCT) imaging of structure and flow, and present several new hemodynamic measurements on embryonic avian hearts at early stages prior to the formation of the four chambers. Using 4-D data, pulsed Doppler measurements could accurately be attained in the inflow and outflow of the heart tube. Also, by employing an en-face slice from the 4-D Doppler image set, measurements of stroke volume and cardiac output are obtained without the need to determine absolute velocity. Finally, an image plane orthogonal to the blood flow is used to determine shear stress by calculating the velocity gradient normal to the endocardium. Hemodynamic measurements will be crucial to identifying genetic and environmental factors that lead to congenital heart defects.

  2. Exploration of the Rapid Effects of Personal Fine Particulate Matter Exposure on Hemodynamics and Vascular Function during the Same Day

    EPA Science Inventory

    Background: Levels of fine particulate matter [≤ 2.5 μm in aerodynamic diameter (PM2.5)] are associated with alterations in arterial hemodynamics and vascular function. However, the characteristics of the same-day exposure–response relationships remain unclear. Object...

  3. Shoshin Beriberi With Low Cardiac Output and Hemodynamic Deterioration Treated Dramatically by Thiamine Administration.

    PubMed

    Imamura, Teruhiko; Kinugawa, Koichiro

    2015-01-01

    "Shoshin beriberi", which is a fulminant form of cardiovascular beriberi accompanied by hemodynamic deterioration with high cardiac output and decreased systemic blood pressure, caused by thiamine deficiency due to alcoholic abuse or malnutrition, is often difficult to address because of its rarity and non-specific symptoms. We here present a patient with a history of alcoholic abuse who had suffered hemodynamic deterioration with extremely low cardiac output refractory to extracorporeal membrane oxygenation and intravenous catecholamine support, which was improved dramatically by bolus intravenous thiamine administration. Such a type with low cardiac output would be the most severe form of Shoshin beriberi, and cannot be rescued without diagnostic administration of thiamine. PMID:26346515

  4. The influence of stenosis degrees and graft suture position on local hemodynamics of coronary bypass

    NASA Astrophysics Data System (ADS)

    Totorean, A. F.; Bernad, S. I.; Susan-Resiga, R. F.

    2016-06-01

    Bypass graft failure is mainly caused by intimal hyperplasia (IH) that occurs at the graft anastomosis after coronary artery bypass grafting (CABG) surgery. It has been shown that local hemodynamics influences the process of IH initiation and progression. A main concern at this type of surgery is to increase the graft patency, respectively to improve the local hemodynamics. This paper analyzes the influence of different degree of stenosis severity and graft suture position on graft patency, taking into consideration the local hemodynamics. Bypass configurations with anastomosis angle of 45° were numerically investigated, with respect to wall shear stress and pressure variation. We can assume that in the conditions of our study, different stenosis degrees and position of the graft suture influence the local blood flow conditions, and, nevertheless, the graft patency.

  5. Basic Perforator Flap Hemodynamic Mathematical Model

    PubMed Central

    Tao, Youlun; Ding, Maochao; Wang, Aiguo; Zhuang, Yuehong; Chang, Shi-Min; Mei, Jin; Hallock, Geoffrey G.

    2016-01-01

    Background: A mathematical model to help explain the hemodynamic characteristics of perforator flaps based on blood flow resistance systems within the flap will serve as a theoretical guide for the future study and clinical applications of these flaps. Methods: There are 3 major blood flow resistance network systems of a perforator flap. These were defined as the blood flow resistance of an anastomosis between artery and artery of adjacent perforasomes, between artery and vein within a perforasome, and then between vein and vein corresponding to the outflow of that perforasome. From this, a calculation could be made of the number of such blood flow resistance network systems that must be crossed for all perforasomes within a perforator flap to predict whether that arrangement would be viable. Results: The summation of blood flow resistance networks from each perforasome in a given perforator flap could predict which portions would likely survive. This mathematical model shows how this is directly dependent on the location of the vascular pedicle to the flap and whether supercharging or superdrainage maneuvers have been added. These configurations will give an estimate of the hemodynamic characteristics for the given flap design. Conclusions: This basic mathematical model can (1) conveniently determine the degree of difficulty for each perforasome within a perforator flap to survive; (2) semiquantitatively allow the calculation of basic hemodynamic parameters; and (3) allow the assessment of the pros and cons expected for each pattern of perforasomes encountered clinically based on predictable hemodynamic observations.

  6. Post-Treatment Hemodynamics of a Basilar Aneurysm and Bifurcation

    SciTech Connect

    Ortega, J; Hartman, J; Rodriguez, J; Maitland, D

    2008-01-16

    Aneurysm re-growth and rupture can sometimes unexpectedly occur following treatment procedures that were initially considered to be successful at the time of treatment and post-operative angiography. In some cases, this can be attributed to surgical clip slippage or endovascular coil compaction. However, there are other cases in which the treatment devices function properly. In these instances, the subsequent complications are due to other factors, perhaps one of which is the post-treatment hemodynamic stress. To investigate whether or not a treatment procedure can subject the parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. The simulations demonstrate that the treatment procedure produces a substantial increase in the wall shear stress. Analysis of the post-treatment flow field indicates that the increase in wall shear stress is due to the impingement of the basilar artery flow upon the aneurysm filling material and to the close proximity of a vortex tube to the artery wall. Calculation of the time-averaged wall shear stress shows that there is a region of the artery exposed to a level of wall shear stress that can cause severe damage to endothelial cells. The results of this study demonstrate that it is possible for a treatment procedure, which successfully excludes the aneurysm from the vascular system and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the immediately adjacent vessel wall.

  7. Echocardiographic and Hemodynamic Predictors of Mortality in Idiopathic Pulmonary Fibrosis

    PubMed Central

    Rivera-Lebron, Belinda N.; Forfia, Paul R.; Kreider, Maryl; Lee, James C.; Holmes, John H.

    2013-01-01

    Background: Idiopathic pulmonary fibrosis (IPF) can lead to the development of pulmonary hypertension, which is associated with an increased risk of death. In pulmonary arterial hypertension, survival is directly related to the capacity of the right ventricle to adapt to elevated pulmonary vascular load. The relative importance of right ventricular function in IPF is not well understood. Our objective was to evaluate right ventricular echocardiographic and hemodynamic predictors of mortality in a cohort of patients with IPF referred for lung transplant evaluation. Methods: We performed a retrospective cohort study of 135 patients who met 2011 American Thoracic Society/European Respiratory Society criteria for IPF and who were evaluated for lung transplantation at the Hospital of the University of Pennsylvania. Results: Right ventricle:left ventricle diameter ratio (hazard ratio [HR], 4.5; 95% CI, 1.7-11.9), moderate to severe right atrial and right ventricular dilation (HR, 2.9; 95% CI, 1.4-5.9; and HR, 2.7; 95% CI, 1.4-5.4, respectively) and right ventricular dysfunction (HR, 5.5; 95% CI, 2.6-11.5) were associated with an increased risk of death. Higher pulmonary vascular resistance was also associated with increased mortality (HR per 1 Wood unit, 1.3; 95% CI, 1.1-1.5). These risk factors were independent of age, sex, race, height, weight, FVC, and lung transplantation status. Other hemodynamic indices, such as mean pulmonary artery pressure and cardiac index, were not associated with outcome. Conclusions: Right-sided heart size and right ventricular dysfunction measured by echocardiography and higher pulmonary vascular resistance by invasive hemodynamic assessment predict mortality in patients with IPF evaluated for lung transplantation. PMID:23450321

  8. Phonocardiographic Assessment of Hemodynamic Response to Balloon Aortic Valvuloplasty

    PubMed Central

    Bush, Howard S.; Ferguson, James J.

    1990-01-01

    The time to systolic murmur peak is a clinical index that is useful in assessing the severity of valvular aortic stenosis. To determine whether phonocardiography could be used to detect a change in the timing of the murmur and thus to measure hemodynamic improvements in elderly balloon aortic valvuloplasty patients, we retrospectively reviewed phonocardiographic tracings of 18 patients taken before and after the procedure. Ten men and 8 women were included in the study; the mean age was 80.7 ± 11.2 years (range, 64 to 90). Phonocardiographic signals were digitized, and the R-wave to murmur peak interval (R-MP) was measured. In 11 patients, the R-MP decreased (mean decrease, 16% ± 11%): of these, 10 had a significant (> 25%) decrease in mean gradient; 10 had a significant (> 25%) decrease in peak-to-peak gradient; and the average increase in aortic valve area was 38%. Seven patients had an increase in R-MP (mean increase, 10% ± 9%): of these, 6 had a decrease in mean gradient of less than 25%; 6 had a decrease in peak-to-peak gradient of less than 25%; and the average increase in aortic valve area was 21%. Pre- and post-balloon aortic valvuloplasty heart rates were not significantly different (71 ± 8 beats/min versus 73 ± 5 beats/min). In this study, hemodynamic improvements after valvuloplasty were manifested by a reduction in the R-MP interval. We conclude that phonocardiography may be a practical, noninvasive method of assessing the hemodynamic response to balloon aortic valvuloplasty. (Texas Heart Institute Journal 1990;17:42-7) PMID:15227188

  9. Acute effects of ferumoxytol on regulation of renal hemodynamics and oxygenation

    PubMed Central

    Cantow, Kathleen; Pohlmann, Andreas; Flemming, Bert; Ferrara, Fabienne; Waiczies, Sonia; Grosenick, Dirk; Niendorf, Thoralf; Seeliger, Erdmann

    2016-01-01

    The superparamagnetic iron oxide nanoparticle ferumoxytol is increasingly used as intravascular contrast agent in magnetic resonance imaging (MRI). This study details the impact of ferumoxytol on regulation of renal hemodynamics and oxygenation. In 10 anesthetized rats, a single intravenous injection of isotonic saline (used as volume control) was followed by three consecutive injections of ferumoxytol to achieve cumulative doses of 6, 10, and 41 mg Fe/kg body mass. Arterial blood pressure, renal blood flow, renal cortical and medullary perfusion and oxygen tension were continuously measured. Regulation of renal hemodynamics and oxygenation was characterized by dedicated interventions: brief periods of suprarenal aortic occlusion, hypoxia, and hyperoxia. None of the three doses of ferumoxytol resulted in significant changes in any of the measured parameters as compared to saline. Ferumoxytol did not significantly alter regulation of renal hemodynamics and oxygenation as studied by aortic occlusion and hypoxia. The only significant effect of ferumoxytol at the highest dose was a blunting of the hyperoxia-induced increase in arterial pressure. Taken together, ferumoxytol has only marginal effects on the regulation of renal hemodynamics and oxygenation. This makes ferumoxytol a prime candidate as contrast agent for renal MRI including the assessment of renal blood volume fraction. PMID:27436132

  10. Acute effects of ferumoxytol on regulation of renal hemodynamics and oxygenation.

    PubMed

    Cantow, Kathleen; Pohlmann, Andreas; Flemming, Bert; Ferrara, Fabienne; Waiczies, Sonia; Grosenick, Dirk; Niendorf, Thoralf; Seeliger, Erdmann

    2016-01-01

    The superparamagnetic iron oxide nanoparticle ferumoxytol is increasingly used as intravascular contrast agent in magnetic resonance imaging (MRI). This study details the impact of ferumoxytol on regulation of renal hemodynamics and oxygenation. In 10 anesthetized rats, a single intravenous injection of isotonic saline (used as volume control) was followed by three consecutive injections of ferumoxytol to achieve cumulative doses of 6, 10, and 41 mg Fe/kg body mass. Arterial blood pressure, renal blood flow, renal cortical and medullary perfusion and oxygen tension were continuously measured. Regulation of renal hemodynamics and oxygenation was characterized by dedicated interventions: brief periods of suprarenal aortic occlusion, hypoxia, and hyperoxia. None of the three doses of ferumoxytol resulted in significant changes in any of the measured parameters as compared to saline. Ferumoxytol did not significantly alter regulation of renal hemodynamics and oxygenation as studied by aortic occlusion and hypoxia. The only significant effect of ferumoxytol at the highest dose was a blunting of the hyperoxia-induced increase in arterial pressure. Taken together, ferumoxytol has only marginal effects on the regulation of renal hemodynamics and oxygenation. This makes ferumoxytol a prime candidate as contrast agent for renal MRI including the assessment of renal blood volume fraction. PMID:27436132

  11. Noninvasive high-speed photoacoustic tomography of cerebral hemodynamics in awake-moving rats

    PubMed Central

    Tang, Jianbo; Xi, Lei; Zhou, Junli; Huang, Hua; Zhang, Tao; Carney, Paul R; Jiang, Huabei

    2015-01-01

    We present a noninvasive method of photoacoustic tomography (PAT) for imaging cerebral hemodynamics in awake-moving rats. The wearable PAT (wPAT) system has a size of 15 mm in height and 33 mm in diameter, and a weight of ~8 g (excluding cabling). The wPAT achieved an imaging rate of 3.33 frames/s with a lateral resolution of 243 μm. Animal experiments were designed to show wPAT feasibility for imaging cerebral hemodynamics on awake-moving animals. Results showed that the cerebral oxy-hemoglobin and deoxy-hemoglobin changed significantly in response to hyperoxia; and, after the injection of pentylenetetrazol (PTZ), cerebral blood volume changed faster over time and larger in amplitude for rats in awake-moving state compared with rats under anesthesia. By providing a light-weight, high-resolution technology for in vivo monitoring of cerebral hemodynamics in awake-behaving animals, it will be possible to develop a comprehensive understanding on how activity alters hemodynamics in normal and diseased states. PMID:26082016

  12. Effect of the serotonin antagonist ketanserin on the hemodynamic and morphological consequences of thrombotic infarction

    SciTech Connect

    Dietrich, W.D.; Busto, R.; Ginsberg, M.D. )

    1989-12-01

    The effect of the serotonin (5-hydroxytryptamine, 5-HT) antagonist ketanserin on the remote hemodynamic consequences of thrombotic brain infarction was studied in rats. Treated rats received an injection of 1 mg/kg ketanserin 30 min before and 1 h following photochemically induced cortical infarction. Local CBF (LCBF) was assessed autoradiographically with ({sup 14}C)iodoantipyrine 4 h following infarction, and chronic infarct size was documented at 5 days. Thrombotic infarction led to significant decreases in LCBF within noninfarcted cortical regions. For example, mean LCBF was decreased to 63, 55, and 65% of control (nontreated normal rats) in ipsilateral frontal, lateral, and auditory cortices, respectively. In rats treated with ketanserin, significant decreases in LCBF were not documented within remote cortical areas compared with controls. In contrast to these hemodynamic effects, morphological analysis of chronic infarct size demonstrated no differences in infarct volume between treated (27 +/- 3 mm3) and nontreated (27 +/- 6 mm3) rats. These data are consistent with the hypothesis that 5-HT is involved in the widespread hemodynamic consequences of experimentally induced thrombotic infarction. Remote hemodynamic consequences of acute infarction can be inhibited without altering final infarct size.

  13. Experimental Comparison of the Hemodynamic Effects of Bifurcating Coronary Stent Implantation Techniques

    NASA Astrophysics Data System (ADS)

    Brindise, Melissa; Vlachos, Pavlos; AETheR Lab Team

    2015-11-01

    Stent implantation in coronary bifurcations imposes unique effects to the blood flow patterns and currently there is no universally accepted stent deployment approach. Despite the fact that stent-induced changes can greatly alter clinical outcomes, no concrete understanding exists regarding the hemodynamic effects of each implantation method. This work presents an experimental evaluation of the hemodynamic differences between implantation techniques. We used four common stent implantation methods including the currently preferred one-stent provisional side branch (PSB) technique and the crush (CRU), Culotte (CUL), and T-stenting (T-PR) two-stent techniques, all deployed by a cardiologist in coronary models. Particle image velocimetry was used to obtain velocity and pressure fields. Wall shear stress (WSS), oscillatory shear index, residence times, and drag and compliance metrics were evaluated and compared against an un-stented case. The results of this study demonstrate that while PSB is preferred, both it and T-PR yielded detrimental hemodynamic effects such as low WSS values. CRU provided polarizing and unbalanced results. CUL demonstrated a symmetric flow field, balanced WSS distribution, and ultimately the most favorable hemodynamic environment.

  14. Multi-scale modeling of hemodynamics in the cardiovascular system

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Liang, Fuyou; Wong, Jasmin; Fujiwara, Takashi; Ye, Wenjing; Tsubota, Ken-iti; Sugawara, Michiko

    2015-08-01

    The human cardiovascular system is a closed-loop and complex vascular network with multi-scaled heterogeneous hemodynamic phenomena. Here, we give a selective review of recent progress in macro-hemodynamic modeling, with a focus on geometrical multi-scale modeling of the vascular network, micro-hemodynamic modeling of microcirculation, as well as blood cellular, subcellular, endothelial biomechanics, and their interaction with arterial vessel mechanics. We describe in detail the methodology of hemodynamic modeling and its potential applications in cardiovascular research and clinical practice. In addition, we present major topics for future study: recent progress of patient-specific hemodynamic modeling in clinical applications, micro-hemodynamic modeling in capillaries and blood cells, and the importance and potential of the multi-scale hemodynamic modeling.

  15. Hemodynamic variables and mortality in cardiogenic shock: a retrospective cohort study

    PubMed Central

    2009-01-01

    Introduction Despite the key role of hemodynamic goals, there are few data addressing the question as to which hemodynamic variables are associated with outcome or should be targeted in cardiogenic shock patients. The aim of this study was to investigate the association between hemodynamic variables and cardiogenic shock mortality. Methods Medical records and the patient data management system of a multidisciplinary intensive care unit (ICU) were reviewed for patients admitted because of cardiogenic shock. In all patients, the hourly variable time integral of hemodynamic variables during the first 24 hours after ICU admission was calculated. If hemodynamic variables were associated with 28-day mortality, the hourly variable time integral of drops below clinically relevant threshold levels was computed. Regression models and receiver operator characteristic analyses were calculated. All statistical models were adjusted for age, admission year, mean catecholamine doses and the Simplified Acute Physiology Score II (excluding hemodynamic counts) in order to account for the influence of age, changes in therapies during the observation period, the severity of cardiovascular failure and the severity of the underlying disease on 28-day mortality. Results One-hundred and nineteen patients were included. Cardiac index (CI) (P = 0.01) and cardiac power index (CPI) (P = 0.03) were the only hemodynamic variables separately associated with mortality. The hourly time integral of CI drops <3, 2.75 (both P = 0.02) and 2.5 (P = 0.03) L/min/m2 was associated with death but not that of CI drops <2 L/min/m2 or lower thresholds (all P > 0.05). The hourly time integral of CPI drops <0.5-0.8 W/m2 (all P = 0.04) was associated with 28-day mortality but not that of CPI drops <0.4 W/m2 or lower thresholds (all P > 0.05). Conclusions During the first 24 hours after intensive care unit admission, CI and CPI are the most important hemodynamic variables separately associated with 28-day

  16. [Minimally invasive hemodynamic monitoring with esophageal echoDoppler].

    PubMed

    Monge, M I; Estella, A; Díaz, J C; Gil, A

    2008-01-01

    Hemodynamic monitoring is a key element in the care of the critical patients, providing an unquestionable aid in the attendance to diagnosis and the choice of the adequate treatment. Minimally invasive devices have been emerging over the past few years as an effective alternative to classic monitoring tools. The esophageal echoDoppler is among these. It makes it possible to obtain continuous and minimally invasive monitoring of the cardiac output in addition to other useful parameters by measuring the blood flow rate and the diameter of the thoracic descending aorta, which provides a sufficiently extensive view of the hemodynamic state of the patient and facilitates early detection of the changes produced by a sudden clinical derangement. Although several studies have demonstrated the usefulness of the esophageal Doppler in the surgical scene, there is scarce and dispersed evidence in the literature on its benefits in critical patients. Nevertheless, its advantages make it an attractive element to take into account within the diagnostic arsenal in the intensive care. The purpose of the following article is to describe how it works, its degree of validation with other monitoring methods and the role of esophageal echoDoppler as a minimally invasive monitoring tool for measuring cardiac output in the daily clinical practice, contributing with our own experience in the critical patient. PMID:18221711

  17. Non-invasive measurements of tissue hemodynamics with hybrid diffuse optical methods

    NASA Astrophysics Data System (ADS)

    Durduran, Turgut

    Diffuse optical techniques were used to measure hemodynamics of tissues non-invasively. Spectroscopy and tomography of the brain, muscle and implanted tumors were carried out in animal models and humans. Two qualitatively different methods, diffuse optical tomography and diffuse correlation tomography, were hybridized permitting simultaneous measurement of total hemoglobin concentration, blood oxygen saturation and blood flow. This combination of information was processed further to derive estimates of oxygen metabolism (e.g. CMRO 2) in tissue. The diffuse correlation measurements of blood flow were demonstrated in human tissues, for the first time, demonstrating continous, non-invasive imaging of oxygen metabolism in large tissue volumes several centimeters below the tissue surface. The bulk of these investigations focussed on cerebral hemodynamics. Extensive validation of this methodology was carried out in in vivo rat brain models. Three dimensional images of deep tissue hemodynamics in middle cerebral artery occlusion and cortical spreading depression (CSD) were obtained. CSD hemodynamics were found to depend strongly on partial pressure of carbon dioxide. The technique was then adapted for measurement of human brain. All optical spectroscopic measurements of CMRO2 during functional activation were obtained through intact human skull non-invasively. Finally, a high spatio-temporal resolution measurement of cerebral blood flow due to somatosensory cortex activation following electrical forepaw stimulation in rats was carried out with laser speckle flowmetry. New analysis methods were introduced for laser speckle flowmetry. In other organs, deep tissue hemodynamics were measured on human calf muscle during exercise and cuff-ischemia and were shown to have some clinical utility for peripheral vascular disease. In mice tumor models, the measured hemodynamics were shown to be predictive of photodynamic therapy efficacy, again suggesting promise of clinical utility

  18. Automatic coronary lumen segmentation with partial volume modeling improves lesions' hemodynamic significance assessment

    NASA Astrophysics Data System (ADS)

    Freiman, M.; Lamash, Y.; Gilboa, G.; Nickisch, H.; Prevrhal, S.; Schmitt, H.; Vembar, M.; Goshen, L.

    2016-03-01

    The determination of hemodynamic significance of coronary artery lesions from cardiac computed tomography angiography (CCTA) based on blood flow simulations has the potential to improve CCTA's specificity, thus resulting in improved clinical decision making. Accurate coronary lumen segmentation required for flow simulation is challenging due to several factors. Specifically, the partial-volume effect (PVE) in small-diameter lumina may result in overestimation of the lumen diameter that can lead to an erroneous hemodynamic significance assessment. In this work, we present a coronary artery segmentation algorithm tailored specifically for flow simulations by accounting for the PVE. Our algorithm detects lumen regions that may be subject to the PVE by analyzing the intensity values along the coronary centerline and integrates this information into a machine-learning based graph min-cut segmentation framework to obtain accurate coronary lumen segmentations. We demonstrate the improvement in hemodynamic significance assessment achieved by accounting for the PVE in the automatic segmentation of 91 coronary artery lesions from 85 patients. We compare hemodynamic significance assessments by means of fractional flow reserve (FFR) resulting from simulations on 3D models generated by our segmentation algorithm with and without accounting for the PVE. By accounting for the PVE we improved the area under the ROC curve for detecting hemodynamically significant CAD by 29% (N=91, 0.85 vs. 0.66, p<0.05, Delong's test) with invasive FFR threshold of 0.8 as the reference standard. Our algorithm has the potential to facilitate non-invasive hemodynamic significance assessment of coronary lesions.

  19. Altered miRNA Signature of Developing Germ-cells in Infertile Patients Relates to the Severity of Spermatogenic Failure and Persists in Spermatozoa

    PubMed Central

    Muñoz, Xavier; Mata, Ana; Bassas, Lluís; Larriba, Sara

    2015-01-01

    The aim of this study was to assess the cellular miRNA expression behaviour in testes with spermatogenic failure (SpF). We performed a high-throughput screen of 623 mature miRNAs by a quantitative RT-qPCR-based approach in histologically well-defined testicular samples with spermatogenic disruption at different germ-cell stages, which revealed altered patterns of miRNA expression. We focussed on the differentially expressed miRNAs whose expression correlated with the number of testicular mature germ-cells and described the combined expression values of a panel of three miRNAs (miR-449a, miR-34c-5p and miR-122) as a predictive test for the presence of mature germ-cells in testicular biopsy. Additionally, we determined decreased cellular miRNA content in developing germ-cells of SpF testis; this was more noticeable the earlier the stage of germ-cell differentiation was affected by maturation failure. Furthermore, we showed that the miRNA expression profile in mature sperm from mild SpF patients was widely altered. Our results suggest that the cellular miRNA content of developed germ-cells depends heavily on the efficacy of the spermatogenic process. What is more, spermatozoa that have fulfilled the differentiation process still retain the dysregulated miRNA pattern observed in the developing SpF germ-cells. This altered miRNA molecular signature may have functional implications for the male gamete. PMID:26648257

  20. The impact of hemodynamic stress on sensory signal processing in the rodent lateral geniculate nucleus

    PubMed Central

    Zitnik, Gerard A.; Clark, Brain D.; Waterhouse, Barry D.

    2013-01-01

    Hemodynamic stress via hypotensive challenge has been shown previously to cause a corticotropin-releasing factor (CRF)-mediated increase in tonic locus coeruleus (LC) activity and consequent release of norepinephrine (NE) in noradrenergic terminal fields. Although alterations in LC-NE can modulate the responsiveness of signal processing neurons along sensory pathways, little is understood regarding how continuous CRF-mediated activation of LC-NE output due to physiologically relevant stressor affects downstream target cell physiology. The goal of the present study was to investigate the effects of a physiological stressor [hemodynamic stress via sodium nitroprusside (SNP) i.v.] on stimulus evoked responses of sensory processing neurons that receive LC inputs. In rat, the dorsal lateral geniculate nucleus (dLGN) of the thalamus is the primary relay for visual information and is a major target of the LC-NE system. We used extracellular recording techniques in the anesthetized rat monitor single dLGN neuron activity during repeated presentation of light stimuli before and during hemodynamic stress. A significant decrease in magnitude occurred, as well as an increase in latency of dLGN stimulus-evoked responses were observed during hemodynamic stress. In another group of animals the CRF antagonist DpheCRF12–41 was infused onto the ipsilateral LC prior to SNP administration. This infusion blocked the hypotension-induced changes in dLGN stimulus-evoked discharge. These results show that CRF-mediated increases in LC-NE due to hemodynamic stress disrupts the transmission of information along thalamic-sensory pathways by: (1) initially reducing signal transmission during onset of the stressor and (2) decreasing the speed of stimulus evoked sensory transmission. PMID:23643838

  1. Oral Contraceptive Use, Muscle Sympathetic Nerve Activity, and Systemic Hemodynamics in Young Women.

    PubMed

    Harvey, Ronee E; Hart, Emma C; Charkoudian, Nisha; Curry, Timothy B; Carter, Jason R; Fu, Qi; Minson, Christopher T; Joyner, Michael J; Barnes, Jill N

    2015-09-01

    Endogenous female sex hormones influence muscle sympathetic nerve activity (MSNA), a regulator of arterial blood pressure and important factor in hypertension development. Although ≈80% of American women report using hormonal contraceptives sometime during their life, the influence of combined oral contraceptives (OCs) on MSNA and systemic hemodynamics remains equivocal. The goal of this study was to determine whether women taking OCs have altered MSNA and hemodynamics (cardiac output and total peripheral resistance) at rest during the placebo phase of OC use compared with women with natural menstrual cycles during the early follicular phase. We retrospectively analyzed data from studies in which healthy, premenopausal women (aged 18-35 years) participated. We collected MSNA values at rest and hemodynamic measurements in women taking OCs (n=53; 25±4 years) and women with natural menstrual cycles (n=74; 25±4 years). Blood pressure was higher in women taking OCs versus those with natural menstrual cycles (mean arterial pressure, 89±1 versus 85±1 mm Hg, respectively; P=0.01), although MSNA was similar in both groups (MSNA burst incidence, 16±1 versus 18±1 bursts/100 heartbeats, respectively; P=0.19). In a subset of women in which detailed hemodynamic data were available, those taking OCs (n=33) had similar cardiac output (4.9±0.2 versus 4.7±0.2 L/min, respectively; P=0.47) and total peripheral resistance (19.2±0.8 versus 20.0±0.9 U, respectively; P=0.51) as women with natural menstrual cycles (n=22). In conclusion, women taking OCs have higher resting blood pressure and similar MSNA and hemodynamics during the placebo phase of OC use when compared with naturally menstruating women in the early follicular phase. PMID:26101348

  2. Oral contraceptive use, muscle sympathetic nerve activity, and systemic hemodynamics in young women

    PubMed Central

    Harvey, Ronee E.; Hart, Emma C.; Charkoudian, Nisha; Curry, Timothy B.; Carter, Jason R.; Fu, Qi; Minson, Christopher T.; Joyner, Michael J.; Barnes, Jill N.

    2015-01-01

    Endogenous female sex hormones influence muscle sympathetic nerve activity (MSNA), a regulator of arterial blood pressure and important factor in hypertension development. While nearly 80% of American women report using hormonal contraceptives sometime during their life, the influence of combined oral contraceptives (OCs) on MSNA and systemic hemodynamics remains equivocal. The goal of this study was to determine if women taking OCs have altered MSNA and hemodynamics (cardiac output and total peripheral resistance) at rest during the placebo phase of OC use compared to women with natural menstrual cycles during the early follicular phase. We retrospectively analyzed data from studies in which healthy, premenopausal women (ages 18–35 years old) participated. We collected MSNA values at rest and hemodynamic measurements in women taking OCs (n=53, 25±4 yr) and women with natural menstrual cycles (n=74, 25±4 yr). Blood pressure was higher in women taking OCs versus those with natural menstrual cycles (mean arterial pressure: 89±1 vs. 85±1 mmHg, respectively; p=0.01), although MSNA was similar in both groups (MSNA burst incidence: 16±1 vs. 18±1 bursts/100 heartbeats, respectively, p=0.19). In a subset of women in which detailed hemodynamic data were available, those taking OCs (n=33) had similar cardiac output (4.9±0.2 vs. 4.7±0.2 L/min, respectively; p=0.47) and total peripheral resistance (19.2±0.8 vs. 20.0±0.9 units, respectively; p=0.51) as women with natural menstrual cycles (n=22). In conclusion, women taking OCs have higher resting blood pressure and similar MSNA and hemodynamics during the placebo phase of OC use compared to naturally menstruating women in the early follicular phase. PMID:26101348

  3. Single-Site Low-Flow Veno-Venous Extracorporeal Lung Support Does Not Influence Hemodynamic Monitoring by Transpulmonary Thermodilution.

    PubMed

    Redwan, Bassam; Ziegeler, Stephan; Freermann, Stefan; Meemann, Thomas; Semik, Michael; Dickgerber, Nicolas; Fischer, Stefan

    2016-01-01

    The application of extracorporeal lung support (ECLS) in patients with acute respiratory distress syndrome is a well-established concept. In patients receiving ECLS therapy, hemodynamic monitoring is often required. However, less is known about the effect of ECLS on hemodynamic measurements. In the present work, the influence of single-site low-flow veno-venous ECLS (LFVV-ECLS) on hemodynamic monitoring by transpulmonary thermodilution (TPTD) was prospectively investigated. Five consecutive patients undergoing single-site LFVV-ECLS for severe hypercapnic respiratory failure were included in this study. For single-site LFVV-ECLS, a 22 Fr twin-port double-lumen cannula was inserted percutaneously into the right jugular vein. Hemodynamic monitoring was performed using the Pulse index Continuous Cardiac Output system. Before ECLS initiation, baseline measurements of cardiac index, systemic vascular resistance, mean arterial pressure, and extravascular lung water (EVLW) were performed. During the first 3 days of ECLS therapy, repeated hemodynamic measurements at different ECLS flow rates were performed. No significant differences were seen in hemodynamic measurements. With respect to EVLW, a significant decrease over the duration of ECLS therapy was observed. This study demonstrates that LFVV-ECLS does not interfere with TPTD. It needs to be further studied if these findings also apply to other ECLS modes. PMID:27045969

  4. The progression from a lower to a higher invasive stage of bladder cancer is associated with severe alterations in glucose and pyruvate metabolism

    SciTech Connect

    Conde, Vanessa R.; Oliveira, Pedro F.; Ramalhosa, Elsa; Pereira, José A.; Alves, Marco G.; Silva, Branca M.

    2015-07-01

    Cancer cells present a particular metabolic behavior. We hypothesized that the progression of bladder cancer could be accompanied by changes in cells glycolytic profile. We studied two human bladder cancer cells, RT4 and TCCSUP, in which the latter represents a more invasive stage. The levels of glucose, pyruvate, alanine and lactate in the extracellular media were measured by Proton Nuclear Magnetic Resonance. The protein expression levels of glucose transporters 1 (GLUT1) and 3 (GLUT3), monocarboxylate transporter 4 (MCT4), phosphofructokinase-1 (PFK1), glutamic-pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) were determined. Our data showed that glucose consumption and GLUT3 levels were similar in both cell lines, but TCCSUP cells displayed lower levels of GLUT1 and PFK expression. An increase in pyruvate consumption, concordant with the higher levels of lactate and alanine production, was also detected in TCCSUP cells. Moreover, TCCSUP cells presented lower protein expression levels of GPT and LDH. These results illustrate that bladder cancer progression is associated with alterations in cells glycolytic profile, namely the switch from glucose to pyruvate consumption in the more aggressive stage. This may be useful to develop new therapies and to identify biomarkers for cancer progression. - Highlights: • Metabolic phenotype of less and high invasive bladder cancer cells was studied. • Bladder cancer progression involves alterations in cells glycolytic profile. • More invasive bladder cancer cells switch from glucose to pyruvate consumption. • Our results may help to identify metabolic biomarkers of bladder cancer progression.

  5. Obesity and major depression: Body-mass index (BMI) is associated with a severe course of disease and specific neurostructural alterations.

    PubMed

    Opel, Nils; Redlich, Ronny; Grotegerd, Dominik; Dohm, Katharina; Heindel, Walter; Kugel, Harald; Arolt, Volker; Dannlowski, Udo

    2015-01-01

    Obesity is one of the most prevalent somatic comorbidities of major depressive disorder (MDD). Both disorders rank among the leading challenges in public health and have been independently characterized by gray matter alterations in partly overlapping brain structures. Hence, it appears crucial to investigate the possibility of a shared neurostructural correlate of this frequent comorbidity as well as its clinical implications. One hundred and fourty-four patients suffering from acute MDD and 141 healthy control subjects underwent structural MRI. Imaging data were analyzed using voxel-based morphometry (VBM). Body-mass-index (BMI) as well as state and course of disease were assessed. Higher BMI was associated with a highly comparable pattern of gray matter reductions in the medial prefrontal cortex, the orbitofrontal cortex, the caudate nucleus and the thalamus in MDD patients and healthy controls alike. In MDD-patients, BMI was associated with a more chronic course of disease and both BMI and chronicity of disorder were related to similar morphometric anomalies in medial prefrontal areas. In MDD, obese subjects might be characterized by a more chronic course of disease. Moreover, obesity and chronicity of disorder seem to share overlapping neurostructural anomalies in prefrontal areas involved in emotion regulation and impulse control. Hence, our data provide evidence for specific morphological alterations underlying this prevalent comorbidity. It further underlines the clinical importance of preventive measures against obesity accompanying MDD treatment. PMID:25462895

  6. 4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics.

    PubMed

    Goenezen, Sevan; Chivukula, Venkat Keshav; Midgett, Madeline; Phan, Ly; Rugonyi, Sandra

    2016-06-01

    Blood flow plays a critical role in regulating embryonic cardiac growth and development, with altered flow leading to congenital heart disease. Progress in the field, however, is hindered by a lack of quantification of hemodynamic conditions in the developing heart. In this study, we present a methodology to quantify blood flow dynamics in the embryonic heart using subject-specific computational fluid dynamics (CFD) models. While the methodology is general, we focused on a model of the chick embryonic heart outflow tract (OFT), which distally connects the heart to the arterial system, and is the region of origin of many congenital cardiac defects. Using structural and Doppler velocity data collected from optical coherence tomography, we generated 4D ([Formula: see text]) embryo-specific CFD models of the heart OFT. To replicate the blood flow dynamics over time during the cardiac cycle, we developed an iterative inverse-method optimization algorithm, which determines the CFD model boundary conditions such that differences between computed velocities and measured velocities at one point within the OFT lumen are minimized. Results from our developed CFD model agree with previously measured hemodynamics in the OFT. Further, computed velocities and measured velocities differ by [Formula: see text]15 % at locations that were not used in the optimization, validating the model. The presented methodology can be used in quantifications of embryonic cardiac hemodynamics under normal and altered blood flow conditions, enabling an in-depth quantitative study of how blood flow influences cardiac development. PMID:26361767

  7. In-vivo optical imaging and spectroscopy of cerebral hemodynamics

    NASA Astrophysics Data System (ADS)

    Zhou, Chao

    Functional optical imaging techniques, such as diffuse optical imaging and spectroscopy and laser speckle imaging (LSI), were used in research and clinical settings to measure cerebral hemodynamics. In this thesis, theoretical and experimental developments of the techniques and their in-vivo applications ranging from small animals to adult humans are demonstrated. Near infrared diffuse optical techniques non-invasively measure hemoglobin concentrations, blood oxygen saturation (diffuse reflectance spectroscopy, DRS) and blood flow (diffuse correlation spectroscopy, DCS) in deep tissues, e.g. brain. A noise model was derived for DCS measurements. Cerebral blood flow (CBF) measured with DCS was validated with arterial-spin-labeling MRI. Three-dimensional CBF tomography was obtained during cortical spreading depression from a rat using the optimized diffuse correlation tomographic method. Cerebral hemodynamics in newborn piglets after traumatic brain injury were continuously monitored optically for six hours to demonstrate the feasibility of using diffuse optical techniques as bedside patient monitors. Cerebral autoregulation in piglets and human stroke patients was demonstrated to be non-invasively assessable via the continuous DCS measurement. Significant differences of CBF responses to head-of-bead maneuvers were observed between the peri- and contra-infarct hemispheres in human stroke patients. A significant portion of patient population showed paradoxical CBF responses, indicating the importance of individualized stroke management. The development of a speckle noise model revealed the source of noise for LSI. LSI was then applied to study the acute functional recovery of the rat brain following transient brain ischemia. The spatial and temporal cerebral blood flow responses to functional stimulation were statistically quantified. The area of activation, and the temporal response to stimulation were found significantly altered by the ischemic insult, while the

  8. Cooling and hemodynamic management in heatstroke: practical recommendations

    PubMed Central

    Bouchama, Abderrezak; Dehbi, Mohammed; Chaves-Carballo, Enrique

    2007-01-01

    Introduction Although rapid cooling and management of circulatory failure are crucial to the prevention of irreversible tissue damage and death in heatstroke, the evidence supporting the optimal cooling method and hemodynamic management has yet to be established. Methods A systematic review of all clinical studies published in Medline (1966 to 2006), CINAHL (Cumulative Index to Nursing & Allied Health Literature) (1982 to 2006), and Cochrane Database was performed using the OVID interface without language restriction. Search terms included heatstroke, sunstroke, and heat stress disorders. Results Fourteen articles reported populations subjected to cooling treatment for classic or exertional heatstroke and included data on cooling time, neurologic morbidity, or mortality. Five additional articles described invasive monitoring with central venous or pulmonary artery catheters. The four clinical trials and 15 observational studies covered a total of 556 patients. A careful analysis of the results obtained indicated that the cooling method based on conduction, namely immersion in iced water, was effective among young people, military personnel, and athletes with exertional heatstroke. There was no evidence to support the superiority of any one cooling technique in classic heatstroke. The effects of non-invasive, evaporative, or conductive-based cooling techniques, singly or combined, appeared to be comparable. No evidence of a specific endpoint temperature for safe cessation of cooling was found. The circulatory alterations in heatstroke were due mostly to a form of distributive shock associated with relative or absolute hypovolemia. Myocardial failure was found to be rare. Conclusion A systematic review of the literature failed to identify reliable clinical data on the optimum treatment of heatstroke. Nonetheless, the findings of this study could serve as a framework for preliminary recommendations in cooling and hemodynamic management of heatstroke until more

  9. [Hemodynamic basis for the development of varicose ulcers and their therapy].

    PubMed

    Recek, C

    2003-09-01

    The prevalence of leg ulcers is about 1%, approximately 75% of them are of venous origin. The precondition for the development of venous ulcers is ambulatory venous hypertension. It is assumed than a linear correlation exists between the severity of ambulatory venous hypertension and the incidence of venous ulcers. Venous ulcers caused by superficial vein reflux are called varicose ulcers and are more frequent than postthrombotic ones. Crossectomy removes the hemodynamic disorder responsible for the development of varicose ulcers and creates conditions for a quick and mostly definitive ulcer healing. In cases with simultaneous reflux in the saphenous and femoral veins the saphenous reflux is responsible for the severity of venous disorder, whereas femoral reflux is hemodynamically unimportant. Selective abolition of saphenous reflux restores normal hemodynamic conditions in such cases. Compressive therapy continues to be the most frequently used therapeutic procedure in the treatment of venous ulcers; it must be considered as a symptomatic measure, because it is not able to substantially affect the underlying venous disorder in spite of the fact that the correctly lying bandage positively influences venous hemodynamics. The diagnostic procedure in patients with leg ulcers should screen out cases with varicose ulcers; abolition of superficial vein reflux can deliver these patients from their annoying disease. PMID:14658257

  10. CHIVA: hemodynamic concept, strategy and results.

    PubMed

    Franceschi, Claude; Cappelli, Massimo; Ermini, Stefano; Gianesini, Sergio; Mendoza, Erika; Passariello, Fausto; Zamboni, Paolo

    2016-02-01

    The first part of this review article provides the physiologic background that sustained the CHIVA principles development. Then the venous networks anatomy and flow patterns are described with pertinent sonographic interpretations, leading to the shunt concept description and to the consequent CHIVA strategy application. An in depth explanation into the hemodynamic conservative cure approach follows, together with pertinent review of the relevant literature. PMID:26044838

  11. Hemodynamic Patterning of the Avian Atrioventricular Valve

    PubMed Central

    Yalcin, Huseyin C.; Shekhar, Akshay; McQuinn, Tim C.; Butcher, Jonathan T.

    2011-01-01

    In this study, we develop an innovative approach to rigorously quantify the evolving hemodynamic environment of the atrioventricular (AV) canal of avian embryos. Ultrasound generated velocity profiles were imported into Micro-Computed Tomography generated anatomically precise cardiac geometries between Hamburger-Hamilton (HH) stages 17 and 30. Computational fluid dynamic simulations were then conducted and iterated until results mimicked in vivo observations. Blood flow in tubular hearts (HH17) was laminar with parallel streamlines, but strong vortices developed simultaneous with expansion of the cushions and septal walls. For all investigated stages, highest wall shear stresses (WSS) are localized to AV canal valve forming regions. Peak WSS increased from 19.34 dynes/cm2 at HH17 to 287.18 dynes/cm2 at HH30, but spatiotemporally averaged WSS became 3.62 dynes/cm2 for HH17 to 9.11 dynes/cm2 for HH30. Hemodynamic changes often preceded and correlated with morphological changes. These results establish a quantitative baseline supporting future hemodynamic analyses and interpretations. PMID:21181939

  12. Chronic hemodynamic unloading regulates the morphologic development of newborn mouse hearts transplanted into the ear of isogeneic adult mice.

    PubMed Central

    Rossi, M. A.

    1992-01-01

    The morphologic development of newborn mouse hearts transplanted into the pinna of the ears of isogeneic adult mice was assessed in comparison to in situ ventricular myocardium of recipients. The grafted hearts became vascularized from the auricular artery at the base of the ear, and although these preparations appeared not to be intrinsically innervated, most of them showed grossly visible pulsatile activity. Since they were not subjected to hemodynamic load due to working against a pressure gradient, this technique provided an interesting experimental model for studies on the growth of chronically unloaded tissue. The ultrastructure of the myocardium from neonatal mouse hearts, which were fixed immediately after dissection, revealed no differences in comparison to previously published observations. By 2 months, there was virtually no change in the myocardial cell size as compared with newborn mouse cardiac tissue. The heterotopic hearts showed a mature ultrastructural appearance, with parallel bands of myofibrils alternating with rows of mitochondria and differentiated intercalated discs comparable to in situ myocardium. The interstitial space was widened due to fibrous tissue, with activated fibroblasts and a few mononuclear cells. In contrast, by 6 months after transplantation, the heterotopic myocardium showed a dispersion of the measured cell diameter of myocytes, with atrophy of a certain population of cells and hypertrophy in others; nevertheless, the mean cell diameter was similar to that observed in 2-month grafts. The myocytes showed significant dissociation from each other in fibrous tissue and a cellular infiltrate composed predominantly of mononuclear cells, and greater variability of the parallel arrangement of cells. They often contained myofibrils coursing in different directions rather than in parallel. Normal-sized or predominantly atrophic degenerated myocytes, characterized by a wide variety of ultrastructural alterations, were present. By 12

  13. Hemodynamic reactions to circulatory stress tests in patients with neurocirculatory dystonia.

    PubMed

    Mäntysaari, M

    1984-01-01

    The hemodynamic reactions of 30 patients with neurocirculatory dystonia (NCD, DaCosta's syndrome) were compared to those of 30 healthy controls during the isometric handgrip test, orthostatic test, Valsalva test and the cold pressor test. The effects of hyperventilation on the ability to hold the breath were studied in both groups using the hyperventilation test. The patients and controls were young men, who were doing their conscript service, and the average age was 20 years in both groups. The diagnosis of NCD was made using the criteria described by Friedman (1947). The patients had several symptoms related to the cardiorespiratory system, the intensity of which varied from time to time and were not closely related to physical effort. In order to exclude organic diseases that could have caused the symptoms the patients were required to have no history of chronic organic diseases. They were also required to have no infectious diseases nor to be convalescents when participating in this study and to have a normal ECG and a normal thorax x-ray. The controls were anamnestically free from chronic diseases. The changes in the blood pressure, heart rate, stroke volume, cardiac index, peripheral vascular resistance and the systolic time intervals during the four tests were measured noninvasively using sphygmomanometry, electro-, phono- and impedance cardiography. The ability to hold the breath after a deep inspiration was similar in the two groups. Immediately after hyperventilation the ability to hold the breath did not improve in the NCD group as much as in the control group. In the orthostatic test the rise in the mean blood pressure was only momentarily greater in the control group than in the NCD group, and the heart rate increased about equally in the two groups. The transthoracic impedance increased significantly more in the controls than in the patients in the head-up position. The alterations in the systolic time intervals immediately after the changes of

  14. Severe White Pine Blister Rust Infection in Whitebark Pine Alters Mountain Pine Beetle (Coleoptera: Curculionidae) Attack Density, Emergence Rate, and Body Size.

    PubMed

    Dooley, Edith M; Six, Diana L

    2015-10-01

    Exotic tree pathogens can cause devastating ecological effects on forests that can be exacerbated when infections increase the likelihood of attack by insects. Current high rates of mortality of whitebark pine (Pinus albicaulis Engelm.) are due to white pine blister rust caused by the exotic fungus, Cronartium ribicola J.C. Fisch, and the native mountain pine beetle (Dendroctonus ponderosae Hopkins). These two mortality agents interact in whitebark pine; mountain pine beetle preferentially selects white pine blister rust-infected whitebark pine over healthy trees, and likelihood of attack has been observed to increase with infection severity. We examined attack and emergence rates, and size and sex ratio of mountain pine beetle in whitebark pines exhibiting varying white pine blister rust infection severities. Mountain pine beetle attack density was lowest on the most severely infected trees, but emergence rates and size of beetles from these trees were greater than those from uninfected and less severely infected trees. Low attack rates on severely infected whitebark pine may indicate these trees have lower defenses and that fewer beetle attacks are needed to kill them. Higher beetle emergence rates from severely infected trees may be due to low intraspecific competition resulting from low attack rates or differences in nutrient quality. PMID:26314009

  15. Using ventilator and cardiovascular graphics in the patient who is hemodynamically unstable.

    PubMed

    Murphy, Bryant A; Durbin, Charles G

    2005-02-01

    The interaction of a mechanical ventilator and the human cardiovascular system is complex. One of the most important effects of positive-pressure ventilation (PPV) is that it can decrease venous return. PPV also alters right- and left-ventricular ejection. Increased lung volume increases right-ventricular size by increasing pulmonary vascular resistance, causing intraventricular cardiac-septum shift, and decreasing left-ventricular filling. Increased intrathoracic pressure reduces afterload on the LV and increases ejection of blood from the LV. Understanding and managing these complex and often opposing interactions in critically ill patients is facilitated by analysis of hemodynamic and ventilator waveforms at the bedside. The relationship of PPV to changes in the arterial pressure waveform gives important information regarding appropriate fluid and vasopressor treatment. This article focuses on effects of respiratory pressures on hemodynamics and considers how cardiac pressures can be transmitted to the airway and cause ventilator malfunction. PMID:15691395

  16. Noninvasive sensors in critical care medicine: near-infrared spectroscopy for the detection of altered microvascular blood flow in severe sepsis and septic shock

    NASA Astrophysics Data System (ADS)

    Walz, J. Matthias; Soller, Babs; Soyemi, Olusola; Yang, Ye; Landry, Michelle; Heard, Stephen O.

    2006-10-01

    It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least 225,000 of which are fatal, resulting in significant utilization of healthcare resources and expenses. Significant progress in the understanding of pathophysiology and treatment of this condition has been made lately. Among the newer treatment strategies for critically ill patients are the administration of early goal directed therapy, and Recombinant Human Activated Protein C (Drotrecogrin alfa (activated) [DTAA]) for severe sepsis. However, mortality remains unacceptably high.

  17. Computational Hemodynamics Involving Artificial Devices

    NASA Technical Reports Server (NTRS)

    Kwak, Dochan; Kiris, Cetin; Feiereisen, William (Technical Monitor)

    2001-01-01

    This paper reports the progress being made towards developing complete blood flow simulation capability in human, especially, in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological characterization of blood. As a first step, computational technology developed for aerospace applications was extended in the recent past to the analysis and development of mechanical devices. The blood flow in these devices is practically incompressible and Newtonian, and thus various incompressible Navier-Stokes solution procedures can be selected depending on the choice of formulations, variables and numerical schemes. Two primitive variable formulations used are discussed as well as the overset grid approach to handle complex moving geometry. This procedure has been applied to several artificial devices. Among these, recent progress made in developing DeBakey axial flow blood pump will be presented from computational point of view. Computational and clinical issues will be discussed in detail as well as additional work needed.

  18. Effect of periodic alterations in shear on vascular macromolecular uptake.

    PubMed

    Friedman, M H; Henderson, J M; Aukerman, J A; Clingan, P A

    2000-01-01

    Experiments were carried out in swine to test the hypothesis that changes in the fluid dynamic environment of the arterial wall, with time constants of several minutes to perhaps a few hours, prompt adaptive responses that transiently increase endothelial permeability. After parenteral Evans Blue Dye (EBD) administration, the hemodynamics of the external iliac arteries of the experimental animals were altered using a reversible arteriovenous femoral shunt. For 3 h, the shunt was opened and closed with a period (tau) between 1-180 min. Subsequently, the animal was euthanized and the iliac vessels were photographed en face to obtain the distribution of EBD-bound albumin uptake by the tissue during its exposure to the dye. Albumin uptake increases with tau in a fashion that can be explained by an a priori model of the adaptive permeability response, with a time constant of about an hour. PMID:11145073

  19. Efficient hemodynamic event detection utilizing relational databases and wavelet analysis

    NASA Technical Reports Server (NTRS)

    Saeed, M.; Mark, R. G.

    2001-01-01

    Development of a temporal query framework for time-oriented medical databases has hitherto been a challenging problem. We describe a novel method for the detection of hemodynamic events in multiparameter trends utilizing wavelet coefficients in a MySQL relational database. Storage of the wavelet coefficients allowed for a compact representation of the trends, and provided robust descriptors for the dynamics of the parameter time series. A data model was developed to allow for simplified queries along several dimensions and time scales. Of particular importance, the data model and wavelet framework allowed for queries to be processed with minimal table-join operations. A web-based search engine was developed to allow for user-defined queries. Typical queries required between 0.01 and 0.02 seconds, with at least two orders of magnitude improvement in speed over conventional queries. This powerful and innovative structure will facilitate research on large-scale time-oriented medical databases.

  20. Comparison of tricuspid and bicuspid aortic valve hemodynamics under steady flow conditions

    NASA Astrophysics Data System (ADS)

    Seaman, Clara; Ward, James; Sucosky, Philippe

    2011-11-01

    The bicuspid aortic valve (BAV), a congenital valvular defect consisting of two leaflets instead of three, is associated with a high prevalence of calcific aortic valve disease (CAVD). CAVD also develops in the normal tricuspid aortic valve (TAV) but its progression in the BAV is more severe and rapid. Although hemodynamic abnormalities are increasingly considered potential pathogenic contributor, the native BAV hemodynamics remain largely unknown. Therefore, this study aims at comparing experimentally the hemodynamic environments in TAV and BAV anatomies. Particle-image velocimetry was used to characterize the flow downstream of a native TAV and a model BAV mounted in a left-heart simulator and subjected to three steady flow rates characterizing different phases of the cardiac cycle. While the TAV developed a jet aligned along the valve axis, the BAV was shown to develop a skewed systolic jet with skewness decreasing with increasing flow rate. Measurement of the transvalvular pressure revealed a valvular resistance up to 50% larger in the BAV than in the TAV. The increase in velocity between the TAV and BAV leads to an increase in shear stress downstream of the valve. This study reveals strong hemodynamic abnormalities in the BAV, which may contribute to CAVD pathogenesis.

  1. [Prediction of human orthostatic tolerance by changes in arterial and venous hemodynamics in the microgravity environment].

    PubMed

    Kotovskaia, A R; Fomin, G A

    2013-01-01

    The authors intentionally present exclusively the results of their recent studies of arterial and venous hemodynamics as predictors of human orthostatic tolerance (OT) during space flight and on return to Earth. There is a sufficient demonstration of the in-flight OT predictability by arterial hemodynamic reactions to LBNP and venous hemodynamic changes in response to the lower extremities occlusion. Three levels of cerebral blood flow deficits in the course of the lower body negative pressure test (LBNP) performed in microgravity were first defined. The authors offer quantitative arguments for the dependence of cerebral flow deficit on the degree of LBNP tolerance degradation. Patterns of arterial hemodynamics during LBNP were used successfully to diagnose the actual orthostatic tolerance and also to follow its trend as flight extended, which attests to the predictability of OT change in an individual cosmonaut on space flight. Occlusion plethysmography of legs revealed three levels of response of the most informative venous parameters (capacity, distensibility and rate of filling) correlating with severity of OT degradation. PMID:25509869

  2. Hemodynamic Consequences of Malignant Ascites in Epithelial Ovarian Cancer Surgery*: A Prospective Substudy of a Randomized Controlled Trial.

    PubMed

    Hunsicker, Oliver; Fotopoulou, Christina; Pietzner, Klaus; Koch, Mandy; Krannich, Alexander; Sehouli, Jalid; Spies, Claudia; Feldheiser, Aarne

    2015-12-01

    vasopressor and fluid demands, whereas the administration of artificial infusion solutions was related to opposite effects.Malignant ascites >500 mL implies increased fluid demands and substantial alterations in circulatory blood flow during cancer surgery. Fresh frozen plasma transfusion promotes recovering hemodynamic stability in patients with malignant ascites >500 mL, in whom artificial infusion solutions could not prevent from hemodynamic deterioration. PMID:26656336

  3. Cerebral Blood Flow Alterations as Assessed by 3D ASL in Cognitive Impairment in Patients with Subcortical Vascular Cognitive Impairment: A Marker for Disease Severity

    PubMed Central

    Sun, Yawen; Cao, Wenwei; Ding, Weina; Wang, Yao; Han, Xu; Zhou, Yan; Xu, Qun; Zhang, Yong; Xu, Jianrong

    2016-01-01

    Abnormal reductions in cortical cerebral blood flow (CBF) have been identified in subcortical vascular cognitive impairment (SVCI). However, little is known about the pattern of CBF reduction in relation with the degree of cognitive impairment. CBF measured with three-dimensional (3D) Arterial Spin Labeling (ASL) perfusion magnetic resonance imaging (MRI) helps detect functional changes in subjects with SVCI. We aimed to compare CBF maps in subcortical ischemic vascular disease (SIVD) subjects with and without cognitive impairment and to detect the relationship of the regions of CBF reduction in the brain with the degree of cognitive impairment according to the z-score. A total of 53 subjects with SVCI and 23 matched SIVD subjects without cognitive impairment (controls), underwent a whole-brain 3D ASL MRI in the resting state. Regional CBF (rCBF) was compared voxel wise by using an analysis of variance design in a statistical parametric mapping program, with patient age and sex as covariates. Correlations were calculated between the rCBF value in the whole brain and the z-score in the 53 subjects with SVCI. Compared with the control subjects, SVCI group demonstrated diffuse decreased CBF in the brain. Significant positive correlations were determined in the rCBF values in the left hippocampus, left superior temporal pole gyrus, right superior frontal orbital lobe, right medial frontal orbital lobe, right middle temporal lobe, left thalamus and right insula with the z-scores in SVCI group. The noninvasively quantified resting CBF demonstrated altered CBF distributions in the SVCI brain. The deficit brain perfusions in the temporal and frontal lobe, hippocampus, thalamus and insula was related to the degree of cognitive impairment. Its relationship to cognition indicates the clinical relevance of this functional marker. Thus, our results provide further evidence for the mechanisms underlying the cognitive deficit in patients with SVCI.

  4. Specific and Common Alterations in Host Gene Transcript Accumulation following Infection of the Chestnut Blight Fungus by Mild and Severe Hypoviruses

    PubMed Central

    Allen, Todd D.; Nuss, Donald L.

    2004-01-01

    We report the use of a cDNA microarray to monitor global transcriptional responses of the chestnut blight fungus, Cryphonectria parasitica, to infection by mild and severe isolates of virulence-attenuating hypoviruses that share 87 to 93% and 90 to 98% identity at the nucleotide and amino acid levels, respectively. Infection by the mild hypovirus isolate CHV1-Euro7 resulted in differential expression of 166 of the ca. 2,200 genes represented on the microarray (90 upregulated and 76 downregulated). This is roughly half the number of genes scored as differentially expressed after infection by the severe isolate, CHV1-EP713 (295 genes; 132 upregulated and 163 downregulated). Comparison of the lists of genes responsive to infection by the two hypovirus isolates revealed 80 virus-common responsive genes. Infection by CHV1-EP713 also caused changes in gene transcript accumulation that were, in general, of greater magnitude than those observed with CHV1-Euro7 infections. Thus, the host transcriptional response to infection by severe hypovirus CHV1-EP713 appears to be considerably more dynamic than the response to infection by the mild isolate CHV1-Euro7. Real-time reverse transcription-PCR was performed on 39 different clones, with false-positive rates of 3 and 8% observed for the microarray-predicted list of genes responsive to CHV1-EP713 and CHV1-Euro7 infections, respectively. This analysis has allowed an initial assignment for ca. 2,200 unique C. parasitica-expressed genes as being unresponsive to hypovirus infection, selectively responsive to a specific hypovirus, or generally responsive to hypovirus infection. PMID:15047830

  5. Very early posttraumatic serum alterations are significantly associated to initial massive RBC substitution, injury severity, multiple organ failure and adverse clinical outcome in multiple injured patients

    PubMed Central

    2009-01-01

    Background Multiple severe trauma frequently leads to massive dysbalances of the human immune system. This phenomenon is known as "Systemic Inflammatory Response Syndrome (SIRS)". SIRS is connected to multiple organ failure and thereby entails higher morbidity and mortality in trauma patients. Pro-and anti-inflammatory cytokines such as Il-6, Il-8 and Il-10 seem to play a superior role in the development of SIRS. Several studies support the hypothesis that the very early cytokine release pattern determines the patients' subsequent clinical course. Most data about interleukins in trauma patients however refer to serum concentrations assessed sometime in the first 24 h, but there is only little information about release dynamics in a small-meshed time frame in the very initial post-trauma period. Patients and methods 58 multiple injured patients (Injury Severity Score > 16 points) were included. Blood samples were drawn on patient admission (not later then 90 minutes after trauma) and at 6 h, 12 h, 24 h, 48 h and 72 h. Il-6, Il-8 and Il-10 were measured using an automated chemiluminescence assay (IMMULITE, Siemens Healthcare Diagnostics GmbH). Interleukin levels were correlated to distinct epidemiological and clinical parameters. Results Interleukin serum concentrations are thoroughly elevated after trauma. Patients with haemorrhagic shock and consecutive massive RBC substitution (n = 27) exhibit higher Il-6, Il-8 and Il-10 levels as compared to patients with minor RBC transfusion extent (n = 31). Interleukin levels also differentiate patients with MOF (n = 43) from such without MOF (n = 15) already at the earliest post trauma time (90 minutes). Il-6, Il-8 and Il-10 concentrations also significantly distinguish patients with adverse outcome (n = 11) from such with favourable outcome (n = 47). Exclusively Il-10 has significant correlation to injury severity (ISS > 35). Conclusion The current study presents an image of the serum Il-6, 8 and 10 releases in multiple

  6. BRCA1 deficiency in ovarian cancer is associated with alteration in expression of several key regulators of cell motility – A proteomics study

    PubMed Central

    Gau, David M; Lesnock, Jamie L; Hood, Brian L; Bhargava, Rohit; Sun, Mai; Darcy, Kathleen; Luthra, Soumya; Chandran, Uma; Conrads, Thomas P; Edwards, Robert P; Kelley, Joseph L; Krivak, Thomas C; Roy, Partha

    2015-01-01

    Functional loss of expression of breast cancer susceptibility gene 1(BRCA1) has been implicated in genomic instability and cancer progression. There is emerging evidence that BRCA1 gene product (BRCA1) also plays a role in cancer cell migration. We performed a quantitative proteomics study of EOC patient tumor tissues and identified changes in expression of several key regulators of actin cytoskeleton/cell adhesion and cell migration (CAPN1, 14-3-3, CAPG, PFN1, SPTBN1, CFN1) associated with loss of BRCA1 function. Gene expression analyses demonstrate that several of these proteomic hits are differentially expressed between early and advanced stage EOC thus suggesting clinical relevance of these proteins to disease progression. By immunohistochemistry of ovarian tumors with BRCA1+/+ and BRCA1null status, we further verified our proteomic-based finding of elevated PFN1 expression associated with BRCA1 deficiency. Finally, we established a causal link between PFN1 and BRCA1-induced changes in cell migration thus uncovering a novel mechanistic basis for BRCA1-dependent regulation of ovarian cancer cell migration. Overall, findings of this study open up multiple avenues by which BRCA1 can potentially regulate migration and metastatic phenotype of EOC cells. PMID:25927284

  7. A CACNB4 mutation shows that altered Ca(v)2.1 function may be a genetic modifier of severe myoclonic epilepsy in infancy.

    PubMed

    Ohmori, Iori; Ouchida, Mamoru; Miki, Takafumi; Mimaki, Nobuyoshi; Kiyonaka, Shigeki; Nishiki, Teiichi; Tomizawa, Kazuhito; Mori, Yasuo; Matsui, Hideki

    2008-12-01

    Mutations of SCN1A, encoding the voltage-gated sodium channel alpha1 subunit, represent the most frequent genetic cause of severe myoclonic epilepsy in infancy (SMEI). The purpose of this study was to determine if mutations in other seizure susceptibility genes are also present and could modify the disease severity. All coding exons of SCN1B, GABRG2, and CACNB4 genes were screened for mutations in 38 SCN1A-mutation-positive SMEI probands. We identified one proband who was heterozygous for a de novo SCN1A nonsense mutation (R568X) and another missense mutation (R468Q) of the CACNB4 gene. The latter mutation was inherited from his father who had a history of febrile seizures. An electrophysiological analysis of heterologous expression system exhibited that R468Q-CACNB4 showed greater Ba(2+) current density compared with the wild-type CACNB4. The greater Ca(v)2.1 currents caused by the R468Q-CACNB4 mutation may increase the neurotransmitter release in the excitatory neurons under the condition of insufficient inhibitory neurons caused primarily by the SCN1A mutation. PMID:18755274

  8. Seizure Duration and Hemodynamic State during Electroconvulsive Therapy: Sodium Thiopental versus Propofol

    PubMed Central

    Jarineshin, Hashem; Kashani, Saeed; Fekrat, Fereydoon; Vatankhah, Majid; Golmirzaei, Javad; Alimolaee, Esmaeel; Zafarpour, Hamid

    2016-01-01

    Introduction: General anesthesia is required for Electroconvulsive Therapy (ECT) and it is usually provided by a hypnotic agent. The seizure duration is important for the treatment, and it is usually accompanied by severe hemodynamic changes. The aim of this study was to compare the effects of sodium thiopental versus Propofol on seizure duration and hemodynamic variables during ECT. Methods: A number of 100 patient-sessions of ECT were included in this randomized clinical trial. The initial hemodynamic state of each patient was recorded. Anesthesia was induced by Sodium thiopental in the 1st group and with Propofol in 2nd group. All the patients received the muscle relaxant succinylcholine. The hemodynamic variables after seizure and seizure duration were recorded. The data were analyzed through SPSS 20 and independent t-test. P<0.05 was considered significant. Results: The mean duration of seizure in the sodium thiopental group was significantly longer than the Propofol group (40.3±16.6 sec versus 32±11.3 sec) (P=0.001). There was no statistically significant difference between the mean energy level applied in the two groups (20.5±3.81 joules in the sodium thiopental versus 20.2±3.49 joules in the Propofol group). The mean systolic and diastolic blood pressure at all times after seizure and mean heart rate at 3 and 5 minutes after seizure were significantly lower in Propofol than sodium thiopental groups. Discussion and Conclusion: Propofol provides a more stable hemodynamic state for the ECT procedures, and its use is highly preferred over sodium thiopental in patients with cardiovascular disease. PMID:26383207

  9. Comparison of Dexmedetomidine and Remifentanil on Airway Reflex and Hemodynamic Changes during Recovery after Craniotomy

    PubMed Central

    Kim, Hyunzu; Min, Kyeong Tae; Lee, Jeong Rim; Ha, Sang Hee; Lee, Woo Kyung; Seo, Jae Hee

    2016-01-01

    Purpose During emergence from anesthesia for a craniotomy, maintenance of hemodynamic stability and prompt evaluation of neurological status is mandatory. The aim of this prospective, randomized, double-blind study was to compare the effects of dexmedetomidine and remifentanil on airway reflex and hemodynamic change in patients undergoing craniotomy. Materials and Methods Seventy-four patients undergoing clipping of unruptured cerebral aneurysm were recruited. In the dexmedetomidine group, patients were administered dexmedetomidine (0.5 µg/kg) for 5 minutes, while the patients of the remifentanil group were administered remifentanil with an effect site concentration of 1.5 ng/mL until endotracheal extubation. The incidence and severity of cough and hemodynamic variables were measured during the recovery period. Hemodynamic variables, respiration rate, and sedation scale were measured after extubation and in the post-anesthetic care unit (PACU). Results The incidence of grade 2 and 3 cough at the point of extubation was 62.5% in the dexmedetomidine group and 53.1% in the remifentanil group (p=0.39). Mean arterial pressure (p=0.01) at admission to the PACU and heart rate (p=0.04 and 0.01, respectively) at admission and at 10 minutes in the PACU were significantly lower in the dexmedetomidine group. Respiration rate was significantly lower in the remifentanil group at 2 minutes (p<0.01) and 5 minutes (p<0.01) after extubation. Conclusion We concluded that a single bolus of dexmedetomidine (0.5 µg/kg) and remifentanil infusion have equal effectiveness in attenuating coughing and hemodynamic changes in patients undergoing cerebral aneurysm clipping; however, dexmedetomidine leads to better preservation of respiration. PMID:27189295

  10. The Influence of Normal and Early Vascular Aging on Hemodynamic Characteristics in Cardio- and Cerebrovascular Systems.

    PubMed

    Yu, Hongtao; Huang, George P; Yang, Zifeng; Liang, Fuyou; Ludwig, Bryan

    2016-06-01

    Age-associated alterations in cardiovascular structure and function induce cardiovascular disease in elderly subjects. To investigate the effects of normal vascular aging (NVA) and early vascular aging (EVA) on hemodynamic characteristics in the circle of Willis (CoW), a closed-loop one-dimensional computational model was developed based on fluid mechanics in the vascular system. The numerical simulations revealed that higher central pulse pressure and augmentation index (AIx) appear in the EVA subjects due to early arrival of reflected waves, resulted in the increase of cardiac afterload compared with the NVA subjects. Moreover, the hemodynamic characteristics in the CoW show that the EVA subjects in an older age display a higher blood pressure than that of the NVA with a complete CoW. Herein, the increased blood pressure and flow rate coexist in the subjects with an incomplete CoW. In conclusion, the hemodynamic characteristics in the aortic tree and CoW related to aging appear to play an important role in causing cardiovascular and intravascular disease. PMID:27019876

  11. Hemodynamic characterization of the diabetic Psammomys obesus--an animal model of type II diabetes mellitus.

    PubMed

    Hilzenrat, N; Sikuler, E; Yaari, A; Maislos, M

    1996-11-01

    The hemodynamic changes occurring early in the course of non-insulin-dependent diabetes mellitus (Type II, NIDDM) are not well understood. We applied the radioactive microspheres technique at an early stage of diabetes in Psammomys abesus (sand rat), an established animal model of spontaneous NIDDM. Ten diabetic and 7 control male animals were studied. Plasma glucose and insulin levels in the diabetic group were significantly higher than in the control group (21.3 +/- 2.1 vs. 6.2 +/- 1.1 mmol/l, and 2,650 +/- 480 vs. 770 +/- 120 pmol/l, respectively). Mean arterial blood pressure, heart rate, cardiac output, splanchnic blood flow, muscular blood flow, and total peripheral resistance were not statistically different between the two groups. Renal blood flow was significantly lower in the diabetic group (7.45 +/- 0.32 vs. 10.48 +/- 0.99 ml/min) and renal arterial resistance was higher (11.65 +/- 0.93 vs. 8.33 +/- 0.76 mm Hg.min/ml) compared with the control group. These results suggest that increased renal resistance and decreased renal blood flow may be the initial hemodynamic alterations in NIDDM. The combination of this animal model with the radioactive microspheres technique provides a new tool for studying the physiopathology, the natural history of hemodynamic changes, and possible therapeutic interventions of Type II diabetes. PMID:8960075

  12. Splanchnic and Systemic Hemodynamics in Cirrhotic Patients With Refractory Ascites. Effect of Peritoneovenous Shunting

    PubMed Central

    Vons, Corinne; Hadengue, Antoine; Lee, Samuel S.; Smadja, Claude; Franco, Dominique

    1991-01-01

    The splanchnic and systemic hemodynamics of 14 patients with refractory ascites were studied and were compared to those of 15 patients with ascites responding to medical treatment. Among the 14 patients, 10 were grade B and 4 C, according to the Pugh classification. Of the 15 patients, 5 were Pugh B and 10 C. In patients with refractory ascites, free hepatic venous pressure was significantly higher and hepatic venous pressure gradient was significantly lower than in patients with responsive ascites. Hepatic and azygos blood flows were not significantly different between the two groups. Cardiac output was lower in patients with refractory ascites (p < 0.05) than in those with responsive ascites. In patients with refractory ascites, six months after peritoneovenous shunting, there was a significant reduction of wedged and free hepatic venous pressures and azygos blood flow. Cardiac output increased by 20% (p < 0.02). This study shows that hemodynamic alterations in patients with refractory ascites is the consequence of increased intraabdominal pressure due to chronic ascites. Six months after peritoneovenous shunting splanchnic and systemic hemodynamics became similar to those observed in patients without ascites. PMID:1842670

  13. 2,3,7,8-Tetrachlorodibenzo-p-dioxin treatment alters eicosanoid levels in several organs of the mouse in an aryl hydrocarbon receptor-dependent fashion

    SciTech Connect

    Bui, Peter; Solaimani, Parrisa; Wu, Xiaomeng; Hankinson, Oliver

    2012-03-01

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) adversely affects many mammalian organs and tissues. These effects are mediated by the aryl hydrocarbon receptor (AHR). CYP1A1, CYP1A2 and CYP1B1 are upregulated by the liganded AHR. These (and other) cytochromes P450 can metabolize arachidonic acid into a variety of bioactive eicosanoids. Towards investigating a potential role of eicosanoids in TCDD toxicity, arachidonic acid, two other unsaturated long-chain fatty acids, and up to twenty-five eicosanoids were measured in five organs/tissues of male and female wild-type and Ahr null mice treated or untreated with TCDD. TCDD generally increased the levels of the four dihydroxyeicosatrienoic acids (DHETs) and (where measured) 5,6-epoxyeicosatrienoic acid and 18-, 19- and 20-hydroxyeicosatrienoic acids (HETEs) in the serum, liver, spleen and lungs, but not the heart, of both sexes, and increased the levels in the serum, liver and spleen of several metabolites that are usually considered products of lipoxygenase activity, but which may also be generated by cytochromes P450. TCDD also increased the levels of the esterified forms of these eicosanoids in the liver in parallel with the corresponding free forms. The levels of prostanoids were generally not affected by TCDD. The above changes did not occur in Ahr null mice, and are therefore mediated by the AHR. TCDD increased the mRNA levels of Cyp1a1, Cyp1a2, Cyp1b1 and the Pla2g12a form of phospholipase A{sub 2} to varying degrees in the different organs, and these increases correlated with some but not all the changes in eicosanoids levels in the organs, suggesting that other enzymes may also be involved. -- Highlights: ► TCDD treatment increases the levels of many eicosanoids in several mouse organs. ► Products of both the cytochrome P450 and classical lipoxygenase pathways are increased. ► These increases are dependent on the aryl hydrocarbon receptor. ► Cyp1a1, Cyp1a2 and Cyp1b1 appear to be responsible for much but

  14. Hemodynamic Simulations in Dialysis Access Fistulae

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Leotta, Daniel; Beach, Kirk; Riley, James; Aliseda, Alberto

    2010-11-01

    Arteriovenous fistulae are created surgically to provide adequate access for dialysis in patients with End-Stage Renal Disease. It has long been hypothesized that the hemodynamic and mechanical forces (such as wall shear stress, wall stretch, or flow- induced wall vibrations) constitute the primary external influence on the remodeling process. Given that nearly 50% of fistulae fail after one year, understanding fistulae hemodynamics is an important step toward improving patency in the clinic. We perform numerical simulations of the flow in patient-specific models of AV fistulae reconstructed from 3D ultrasound scans with physiologically-realistic boundary conditions also obtained from Doppler ultrasound. Comparison of the flow features in different geometries and configurations e.g. end-to-side vs. side-to-side, with the in vivo longitudinal outcomes will allow us to hypothesize which flow conditions are conducive to fistulae success or failure. The flow inertia and pulsatility in the simulations (mean Re 700, max Re 2000, Wo 4) give rise to complex secondary flows and coherent vortices, further complicating the spatio- temporal variability of the wall pressure and shear stresses. Even in mature fistulae, the anastomotic regions are subjected to non-physiological shear stresses (>10.12pcPa) which may potentially lead to complications.

  15. A hemodynamic model for layered BOLD signals.

    PubMed

    Heinzle, Jakob; Koopmans, Peter J; den Ouden, Hanneke E M; Raman, Sudhir; Stephan, Klaas Enno

    2016-01-15

    High-resolution blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) at the sub-millimeter scale has become feasible with recent advances in MR technology. In principle, this would enable the study of layered cortical circuits, one of the fundaments of cortical computation. However, the spatial layout of cortical blood supply may become an important confound at such high resolution. In particular, venous blood draining back to the cortical surface perpendicularly to the layered structure is expected to influence the measured responses in different layers. Here, we present an extension of a hemodynamic model commonly used for analyzing fMRI data (in dynamic causal models or biophysical network models) that accounts for such blood draining effects by coupling local hemodynamics across layers. We illustrate the properties of the model and its inversion by a series of simulations and show that it successfully captures layered fMRI data obtained during a simple visual experiment. We conclude that for future studies of the dynamics of layered neuronal circuits with high-resolution fMRI, it will be pivotal to include effects of blood draining, particularly when trying to infer on the layer-specific connections in cortex--a theme of key relevance for brain disorders like schizophrenia and for theories of brain function such as predictive coding. PMID:26484827

  16. Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

    NASA Astrophysics Data System (ADS)

    Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

    Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 ° head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 ° upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alterating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

  17. Effect of ocular shape and vascular geometry on retinal hemodynamics: a computational model.

    PubMed

    Dziubek, Andrea; Guidoboni, Giovanna; Harris, Alon; Hirani, Anil N; Rusjan, Edmond; Thistleton, William

    2016-08-01

    A computational model for retinal hemodynamics accounting for ocular curvature is presented. The model combines (i) a hierarchical Darcy model for the flow through small arterioles, capillaries and small venules in the retinal tissue, where blood vessels of different size are comprised in different hierarchical levels of a porous medium; and (ii) a one-dimensional network model for the blood flow through retinal arterioles and venules of larger size. The non-planar ocular shape is included by (i) defining the hierarchical Darcy flow model on a two-dimensional curved surface embedded in the three-dimensional space; and (ii) mapping the simplified one-dimensional network model onto the curved surface. The model is solved numerically using a finite element method in which spatial domain and hierarchical levels are discretized separately. For the finite element method, we use an exterior calculus-based implementation which permits an easier treatment of non-planar domains. Numerical solutions are verified against suitably constructed analytical solutions. Numerical experiments are performed to investigate how retinal hemodynamics is influenced by the ocular shape (sphere, oblate spheroid, prolate spheroid and barrel are compared) and vascular architecture (four vascular arcs and a branching vascular tree are compared). The model predictions show that changes in ocular shape induce non-uniform alterations of blood pressure and velocity in the retina. In particular, we found that (i) the temporal region is affected the least by changes in ocular shape, and (ii) the barrel shape departs the most from the hemispherical reference geometry in terms of associated pressure and velocity distributions in the retinal microvasculature. These results support the clinical hypothesis that alterations in ocular shape, such as those occurring in myopic eyes, might be associated with pathological alterations in retinal hemodynamics. PMID:26445874

  18. Inflammation severely alters thyroid hormone signaling in the central nervous system during experimental allergic encephalomyelitis in rat: Direct impact on OPCs differentiation failure.

    PubMed

    Fernández, Mercedes; Baldassarro, Vito A; Sivilia, Sandra; Giardino, Luciana; Calzà, Laura

    2016-09-01

    Differentiation of oligodendrocyte precursor cells (OPCs) into myelinating oligodendrocytes is severely impaired by inflammatory cytokines and this could lead to remyelination failure in inflammatory/demyelinating diseases. Due to the role of thyroid hormone in the maturation of OPCs and developmental myelination, in this study we investigated (i) the possible occurrence of dysregulation of thyroid hormone signaling in the CNS tissue during experimental neuroinflammation; (ii) the possible impact of inflammatory cytokines on thyroid hormone signaling and OPCs differentiation in vitro. The disease model is the experimental allergic encephalomyelitis in female Dark-Agouti rats, whereas in vitro experiments were carried out in OPCs derived from neural stem cells. The main results are the following: (i) a strong upregulation of cytokine mRNA expression level was found in the spinal cord during experimental allergic encephalomyelitis; (ii) thyroid hormone signaling in the spinal cord (thyroid hormone receptors; deiodinase; thyroid hormone membrane transporter) is substantially downregulated, due to the upregulation of the thyroid hormone inactivating enzyme deiodinase 3 and the downregulation of thyroid hormone receptors, as investigated at mRNA expression level; (iii) when exposed to inflammatory cytokines, deiodinase 3 is upregulated in OPCs as well, and OPCs differentiation is blocked; (iv) deiodinase 3 inhibition by iopanoic acid recovers OPCs differentiation in the presence on inflammatory cytokines. These data suggest that cellular hypothyroidism occurs during experimental allergic encephalomyelitis, possibly impacting on thyroid hormone-dependent cellular processes, including maturation of OPCs into myelinating oligodendrocytes. GLIA 2016;64:1573-1589. PMID:27404574

  19. Proteomic and Real-Time PCR analyses of Saccharomyces cerevisiae VL3 exposed to microcystin-LR reveals a set of protein alterations transversal to several eukaryotic models.

    PubMed

    Valério, Elisabete; Campos, Alexandre; Osório, Hugo; Vasconcelos, Vitor

    2016-03-15

    Some of the most common toxins present in freshwater, in particular microcystins (MCs), are produced by cyanobacteria. These toxins have a negative impact on human health, being associated with episodes of acute hepatotoxicity and being considered potentially carcinogenic to humans. To date the exact mechanisms of MC-induced toxicity and tumor promotion were not completely elucidated. To get new insights underlying microcystin-LR (MCLR) molecular mechanisms of toxicity we have performed the proteomic profiling using two-dimensional electrophoresis and MALDI-TOF/TOF of Saccharomyces cerevisiae cells exposed for 4 h-1 nM and 1 μM of MCLR, and compared them to the control (cells not exposed to MCLR). We identified 14 differentially expressed proteins. The identified proteins are involved in metabolism, genotoxicity, cytotoxicity and stress response. Furthermore, we evaluated the relative expression of yeast's PP1 and PP2A genes and also of genes from the Base Excision Repair (BER) DNA-repair system, and observed that three out of the five genes analyzed displayed dose-dependent responses. Overall, the different proteins and genes affected are related to oxidative stress and apoptosis, thus reinforcing that it is probably the main mechanism of MCLR toxicity transversal to several organisms, especially at lower doses. Notwithstanding these MCLR responsive proteins could be object of further studies to evaluate their suitability as biomarkers of exposure to the toxin. PMID:26806210

  20. Conditioning with rabbit versus horse ATG dramatically alters clinical outcomes in identical twins with severe aplastic anemia transplanted with the same allogeneic donor.

    PubMed

    Vo, P T; Pantin, J; Ramos, C; Cook, L; Cho, E; Kurlander, R; Khuu, H; Barrett, J; Leitman, S; Childs, R W

    2015-01-01

    Severe aplastic anemia (SAA) is a rare disorder leading to bone marrow failure, which if left untreated, is invariably fatal. Conventional therapies with immunosuppressive therapy or allogeneic hematopoietic stem cell transplantation (HSCT) are highly effective. HSCT can offer a greater outcome in younger patients who have an available HLA match-related donor. Recent studies showing the addition of antithymocyte globulin (ATG) to the conditioning regimen improves engraftment and reduces the risk of graft-versus-host disease (GVHD).There are currently two ATG preparations in the USA, equine (or horse) and rabbit ATG. These agents are pharmacologically distinct, having significant differences in their pharmacokinetics and in vivo immunosuppressive effects [N Engl J Med 365(5):430-438, 2011]. Here, we report a case of two monozygotic twins with constitutional SAA that evolved to myelodysplastic syndrome (MDS) who both underwent allogeneic peripheral blood stem cell transplantation (PBSC) from the same single HLA antigen mismatched sibling donor with the only difference in the transplant regimen being the type of ATG used in the preparative regimen; one twin received horse ATG and the other received rabbit ATG during conditioning. This report emphasizes that dramatic differences in donor T cell chimerism and clinical outcomes including GVHD can occur as a consequence of the type of ATG that is utilized in the transplant conditioning regimen. These differences highlight that these agents should not be considered interchangeable drugs when used in this setting. PMID:26113077

  1. The plasticizer benzyl butyl phthalate (BBP) alters the ecdysone hormone pathway, the cellular response to stress, the energy metabolism, and several detoxication mechanisms in Chironomus riparius larvae.

    PubMed

    Herrero, Óscar; Planelló, Rosario; Morcillo, Gloria

    2015-06-01

    Butyl benzyl phthalate (BBP) has been extensively used worldwide as a plasticizer in the polyvinyl chloride (PVC) industry and the manufacturing of many other products, and its presence in the aquatic environment is expected for decades. In the present study, the toxicity of BBP was investigated in Chironomus riparius aquatic larvae. The effects of acute 24-h and 48-h exposures to a wide range of BBP doses were evaluated at the molecular level by analysing changes in genes related to the stress response, the endocrine system, the energy metabolism, and detoxication pathways, as well as in the enzyme activity of glutathione S-transferase. BBP caused a dose and time-dependent toxicity in most of the selected biomarkers. 24-h exposures to high doses affected larval survival and lead to a significant response of several heat-shock genes (hsp70, hsp40, and hsp27), and to a clear endocrine disrupting effect by upregulating the ecdysone receptor gene (EcR). Longer treatments with low doses triggered a general repression of transcription and GST activity. Furthermore, delayed toxicity studies were specially relevant, since they allowed us to detect unpredictable toxic effects, not immediately manifested after contact with the phthalate. This study provides novel and interesting results on the toxic effects of BBP in C. riparius and highlights the suitability of this organism for ecotoxicological risk assessment, especially in aquatic ecosystems. PMID:25725395

  2. Local and global contributions to hemodynamic activity in mouse cortex.

    PubMed

    Pisauro, M Andrea; Benucci, Andrea; Carandini, Matteo

    2016-06-01

    Imaging techniques such as functional magnetic resonance imaging seek to estimate neural signals in local brain regions through measurements of hemodynamic activity. However, hemodynamic activity is accompanied by large vascular fluctuations of unclear significance. To characterize these fluctuations and their impact on estimates of neural signals, we used optical imaging in visual cortex of awake mice. We found that hemodynamic activity can be expressed as the sum of two components, one local and one global. The local component reflected presumed neural signals driven by visual stimuli in the appropriate retinotopic region. The global component constituted large fluctuations shared by larger cortical regions, which extend beyond visual cortex. These fluctuations varied from trial to trial, but they did not constitute noise; they correlated with pupil diameter, suggesting that they reflect variations in arousal or alertness. Distinguishing local and global contributions to hemodynamic activity may help understand neurovascular coupling and interpret measurements of hemodynamic responses. PMID:26984421

  3. Local and global contributions to hemodynamic activity in mouse cortex

    PubMed Central

    Pisauro, M. Andrea; Benucci, Andrea

    2016-01-01

    Imaging techniques such as functional magnetic resonance imaging seek to estimate neural signals in local brain regions through measurements of hemodynamic activity. However, hemodynamic activity is accompanied by large vascular fluctuations of unclear significance. To characterize these fluctuations and their impact on estimates of neural signals, we used optical imaging in visual cortex of awake mice. We found that hemodynamic activity can be expressed as the sum of two components, one local and one global. The local component reflected presumed neural signals driven by visual stimuli in the appropriate retinotopic region. The global component constituted large fluctuations shared by larger cortical regions, which extend beyond visual cortex. These fluctuations varied from trial to trial, but they did not constitute noise; they correlated with pupil diameter, suggesting that they reflect variations in arousal or alertness. Distinguishing local and global contributions to hemodynamic activity may help understand neurovascular coupling and interpret measurements of hemodynamic responses. PMID:26984421

  4. Early administration of probiotics alters bacterial colonization and limits diet-induced gut dysfunction and severity of necrotizing enterocolitis in preterm pigs.

    PubMed

    Siggers, Richard H; Siggers, Jayda; Boye, Mette; Thymann, Thomas; Mølbak, Lars; Leser, Thomas; Jensen, Bent B; Sangild, Per T

    2008-08-01

    Following preterm birth, bacterial colonization and enteral formula feeding predispose neonates to gut dysfunction and necrotizing enterocolitis (NEC), a serious gastrointestinal inflammatory disease. We hypothesized that administration of probiotics would beneficially influence early bacterial colonization, thereby reducing the susceptibility to formula-induced gut atrophy, dysfunction, and NEC. Caesarean-delivered preterm pigs were provided total parenteral nutrition (1.5 d) followed by enteral feeding (2 d) with porcine colostrum (COLOS; n = 5), formula (FORM; n = 9), or formula with probiotics (FORM-P; Bifidobacterium animalis and Lactobacillus: L. acidophilus, L. casei, L. pentosus, L. plantarum; n = 13). Clinical NEC scores were reduced (P < 0.05) in FORM-P (2.0 +/- 0.2) and COLOS groups (1.7 +/- 0.5) compared with FORM pigs (3.4 +/- 0.6). Lower NEC scores were associated with elevated intestinal weight, mucosa proportion, villus height, RNA integrity, and brush border aminopeptidase A and N activities, and lower gastric organic acid concentration in the FORM-P and COLOS groups (P < 0.05). Diversity of the mucosa-associated bacteria in the distal small intestine was similar among formula-fed pigs, yet the abundance of specific bacterial groups differed between FORM-P and FORM pigs. FORM-P pigs had lower colonization density of a potential pathogen, Clostridium perfringens, and had commensal Lactobacillus bacteria more closely associated with enterocytes along the villus-crypt axis relative to FORM pigs. These results suggest that probiotic administration immediately after birth promotes the colonization of a beneficial commensal microbiota capable of limiting the formula-induced mucosal atrophy, dysfunction, and pathogen load in preterm neonates, thereby reducing the incidence and severity of NEC. PMID:18641188

  5. 2,3,7,8- Te trachlorodibenzo-p-dioxin treatment alters eicosanoid levels in several organs of the mouse in an aryl hydrocarbon receptor-dependent fashion

    PubMed Central

    Bui, Peter; Solaimani, Parrisa; Wu, Xiaomeng; Hankinson, Oliver

    2012-01-01

    2,3,7,8- Te trachlorodibenzo- p-dioxin (TCDD) adversely affects many mammalian organs and tissues. These effects are mediated by the aryl hydrocarbon receptor (AHR). CYP1A1, CYP1A2 and CYP1B1 are upregulated by the liganded AHR. These (and other) cytochromes P450 can metabolize arachidonic acid into a variety of bioactive eicosanoids. Towards investigating a potential role of eicosanoids in TCDD toxicity, arachidonic acid, two other unsaturated long-chain fatty acids, and up to twenty-three eicosanoids were measured in five organs/tissues of male and female wild-type and Ahr null mice treated or untreated with TCDD. TCDD generally increased the levels of the four dihydroxyeicosatrienoic acids (DHETs) and (where measured) 5,6-epoxyeicosatrienoic acid and 18-, 19- and 20-hydroxyeicosatrienoic acids (HETEs) in the serum, liver, spleen and lungs, but not the heart, of both sexes, and increased the levels in the serum, liver and spleen of several metabolites that are usually considered products of lipoxygenase activity, but which may also be generated by cytochromes P450. TCDD also increased the levels of the esterified forms of these eicosanoids in the liver in parallel with the corresponding free forms. The levels of prostanoids were generally not affected by TCDD. The above changes did not occur in Ahr null mice, and are therefore mediated by the AHR. TCDD increased the mRNA levels of Cyp1a1, Cyp1a2, Cyp1b1 and the Pla2g12a form of phospholipase A2 to varying degrees in the different organs, and these increases correlated with some but not all the changes in eicosanoids levels in the organs, suggesting that other enzymes may also be involved. PMID:22230337

  6. Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats.

    PubMed

    Fisch, Sudeshna; Liao, Ronglih; Hsiao, Li-Li; Lu, Tzongshi

    2016-01-01

    The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also

  7. Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats

    PubMed Central

    Fisch, Sudeshna; Liao, Ronglih; Hsiao, Li-Li; Lu, Tzongshi

    2016-01-01

    The kidney normally functions to maintain hemodynamic homeostasis and is a major site of damage caused by drug toxicity. Drug-induced nephrotoxicity is estimated to contribute to 19- 25% of all clinical cases of acute kidney injury (AKI) in critically ill patients. AKI detection has historically relied on metrics such as serum creatinine (sCr) or blood urea nitrogen (BUN) which are demonstrably inadequate in full assessment of nephrotoxicity in the early phase of renal dysfunction. Currently, there is no robust diagnostic method to accurately detect hemodynamic alteration in the early phase of AKI while such alterations might actually precede the rise in serum biomarker levels. Such early detection can help clinicians make an accurate diagnosis and help in in decision making for therapeutic strategy. Rats were treated with Cisplatin to induce AKI. Nephrotoxicity was assessed for six days using high-frequency sonography, sCr measurement and upon histopathology of kidney. Hemodynamic evaluation using 2D and Color-Doppler images were used to serially study nephrotoxicity in rats, using the sonography. Our data showed successful drug-induced kidney injury in adult rats by histological examination. Color-Doppler based sonographic assessment of AKI indicated that resistive-index (RI) and pulsatile-index (PI) were increased in the treatment group; and peak-systolic velocity (mm/s), end-diastolic velocity (mm/s) and velocity-time integral (VTI, mm) were decreased in renal arteries in the same group. Importantly, these hemodynamic changes evaluated by sonography preceded the rise of sCr levels. Sonography-based indices such as RI or PI can thus be useful predictive markers of declining renal function in rodents. From our sonography-based observations in the kidneys of rats that underwent AKI, we showed that these noninvasive hemodynamic measurements may consider as an accurate, sensitive and robust method in detecting early stage kidney dysfunction. This study also

  8. Hemodynamic and Biologic Determinates of Arteriovenous Fistula Outcomes in Renal Failure Patients

    PubMed Central

    Hammes, Mary

    2015-01-01

    The outcome of patients with end-stage renal disease on hemodialysis depends on a functioning vascular access. Although a variety of access options are available, the arteriovenous fistula remains the best vascular access. Unfortunately the success rate of mature fistula use remains poor. The creation of an arteriovenous fistula is followed by altered hemodynamic and biological changes that may result in neointimal hyperplasia and eventual venous stenosis. This review provides an overview of these changes and the needed research to provide a long lasting vascular access and hence improve outcomes for patients with end-stage renal disease. PMID:26495286

  9. Nonlinear extension of a hemodynamic linear model for coherent hemodynamics spectroscopy.

    PubMed

    Sassaroli, Angelo; Kainerstorfer, Jana M; Fantini, Sergio

    2016-01-21

    In this work, we are proposing an extension of a recent hemodynamic model (Fantini, 2014a), which was developed within the framework of a novel approach to the study of tissue hemodynamics, named coherent hemodynamics spectroscopy (CHS). The previous hemodynamic model, from a signal processing viewpoint, treats the tissue microvasculature as a linear time-invariant system, and considers changes of blood volume, capillary blood flow velocity and the rate of oxygen diffusion as inputs, and the changes of oxy-, deoxy-, and total hemoglobin concentrations (measured in near infrared spectroscopy) as outputs. The model has been used also as a forward solver in an inversion procedure to retrieve quantitative parameters that assess physiological and biological processes such as microcirculation, cerebral autoregulation, tissue metabolic rate of oxygen, and oxygen extraction fraction. Within the assumption of "small" capillary blood flow velocity oscillations the model showed that the capillary and venous compartments "respond" to this input as low pass filters, characterized by two distinct impulse response functions. In this work, we do not make the assumption of "small" perturbations of capillary blood flow velocity by solving without approximations the partial differential equation that governs the spatio-temporal behavior of hemoglobin saturation in capillary and venous blood. Preliminary comparison between the linear time-invariant model and the extended model (here identified as nonlinear model) are shown for the relevant parameters measured in CHS as a function of the oscillation frequency (CHS spectra). We have found that for capillary blood flow velocity oscillations with amplitudes up to 10% of the baseline value (which reflect typical scenarios in CHS), the discrepancies between CHS spectra obtained with the linear and nonlinear models are negligible. For larger oscillations (~50%) the linear and nonlinear models yield CHS spectra with differences within typical

  10. Altered glucose metabolism rather than naive type 2 diabetes mellitus (T2DM) is related to vitamin D status in severe obesity

    PubMed Central

    2014-01-01

    Context The last decades have provided insights into vitamin D physiology linked to glucose homeostasis. Uncertainties remain in obesity due to its intrinsic effects on vitamin D and glucose tolerance. Objectives To assess the relationship between vitamin D and glucose abnormalities in severely obese individuals previously unknown to suffer from abnormal glucose metabolism. Setting Tertiary care centre. Patients 524 obese patients (50.3 ± 14.9 yrs; BMI, 47.7 ± 7.3 kg/m2) screened by OGTT, HbA1c and the lipid profile. Vitamin D status was assessed by 25(OH)D3, PTH and electrolyte levels. 25(OH)D3 deficiency/insufficiency were set at 20 and 30 ng/ml, respectively. All comparative and regression analyses were controlled for age, BMI and gender. Results The prevalence of vitamin D deficiency/insufficiency and secondary hyperparathyroidism were 95% and 50.8%, respectively. Normal glucose tolerance (NGT), impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) were found in 37.8%, 40.5% and 21.7% of cases, respectively. Large variations in metabolic parameters were seen across categories of vitamin D status, but the only significant differences were found for C-peptide, tryglicerides, LDL- and HDL-cholesterol levels (p < 0.05 for all). The prevalence of vitamin D deficiency was documented to be slightly but significantly more frequent in glucose-intolerant patients (IFG + IGT + T2DM) compared to the -normotolerant counterpart (87% vs. 80%, p < 0.05). In partial correlation analyses, there was no association between vitamin D levels and glucose-related markers but for HbA1c (r = −0.091, p < 0.05), and both basal and OGTT-stimulated insulin levels (r = 0.097 and r = 0.099; p < 0.05 for all). Vitamin D levels were also correlated to HDL-cholesterol (r = 0.13, p = 0.002). Multivariate regression analysis inclusive of vitamin D, age, BMI, gender and fat mass as

  11. Monitoring changes in hemodynamics following optogenetic stimulation

    NASA Astrophysics Data System (ADS)

    Frye, Seth

    The brain is composed of billions of neurons, all of which connected through a vast network. After years of study and applications of different technologies and techniques, there are still more questions than answers when it comes to the fundamental functions of the brain. This project aims to provide a new tool which can be used to gain a better understanding of the fundamental mechanisms that govern neurological processes inside the brain. In order for neural networks to operate, blood has to be supplied through neighboring blood vessels. As such, the increase or decrease in the blood supply has been used as an indicator of neural activity. The neural activity and blood supply relationship is known as neural vasculature coupling. Monitoring the hemodynamics is used as an indicator of neurological activity, but the causal relationship is an area of current research. Gaining a better understanding of the coupling of neural activity and the surrounding vasculature provides a more accurate methodology to evaluate regional neural activity. The new optical technology applied in this project provides a set of tools to both stimulate and monitor this coupling relationship. Optogenetics provides the capability of stimulating neural activity using specific wavelengths of light. Essentially this tool allows for the direct stimulation of networks of neurons by simply shining one color of light onto the brain. Optical Coherence Tomography (OCT), another new optical technology applied in this project, can record volumetric images of blood vessels and flow using only infrared light. The combination of the two optical technologies is then capable of stimulating neural activity and monitoring the hemodynamic response inside the brain using only light. As a result of this project we have successfully demonstrated the capability of both stimulating and imaging the brain using new optical technologies. The optical stimulation of neural activity has evoked a direct hemodynamic effect

  12. Early and late stimulus-evoked cortical hemodynamic responses provide insight into the neurogenic nature of neurovascular coupling

    PubMed Central

    Kennerley, Aneurin J; Harris, Sam; Bruyns-Haylett, Michael; Boorman, Luke; Zheng, Ying; Jones, Myles; Berwick, Jason

    2012-01-01

    Understanding neurovascular coupling is a prerequisite for the interpretation of results obtained from modern neuroimaging techniques. This study investigated the hemodynamic and neural responses in rat somatosensory cortex elicited by 16 seconds electrical whisker stimuli. Hemodynamics were measured by optical imaging spectroscopy and neural activity by multichannel electrophysiology. Previous studies have suggested that the whisker-evoked hemodynamic response contains two mechanisms, a transient ‘backwards' dilation of the middle cerebral artery, followed by an increase in blood volume localized to the site of neural activity. To distinguish between the mechanisms responsible for these aspects of the response, we presented whisker stimuli during normocapnia (‘control'), and during a high level of hypercapnia. Hypercapnia was used to ‘predilate' arteries and thus possibly ‘inhibit' aspects of the response related to the ‘early' mechanism. Indeed, hemodynamic data suggested that the transient stimulus-evoked response was absent under hypercapnia. However, evoked neural responses were also altered during hypercapnia and convolution of the neural responses from both the normocapnic and hypercapnic conditions with a canonical impulse response function, suggested that neurovascular coupling was similar in both conditions. Although data did not clearly dissociate early and late vascular responses, they suggest that the neurovascular coupling relationship is neurogenic in origin. PMID:22126914

  13. Stroke volume optimization: the new hemodynamic algorithm.

    PubMed

    Johnson, Alexander; Ahrens, Thomas

    2015-02-01

    Critical care practices have evolved to rely more on physical assessments for monitoring cardiac output and evaluating fluid volume status because these assessments are less invasive and more convenient to use than is a pulmonary artery catheter. Despite this trend, level of consciousness, central venous pressure, urine output, heart rate, and blood pressure remain assessments that are slow to be changed, potentially misleading, and often manifested as late indications of decreased cardiac output. The hemodynamic optimization strategy called stroke volume optimization might provide a proactive guide for clinicians to optimize a patient's status before late indications of a worsening condition occur. The evidence supporting use of the stroke volume optimization algorithm to treat hypovolemia is increasing. Many of the cardiac output monitor technologies today measure stroke volume, as well as the parameters that comprise stroke volume: preload, afterload, and contractility. PMID:25639574

  14. Effects of phacoemulsification surgery on ocular hemodynamics

    PubMed Central

    Turk, Adem; Mollamehmetoglu, Suleyman; Imamoglu, Halil Ibrahim; Kola, Mehmet; Erdol, Hidayet; Akyol, Nurettin

    2013-01-01

    AIM To evaluate the possible effects of phacoemulsification cataract surgery on ocular hemodynamics. METHODS In this prospective study, intraocular pressure (IOP), pulsatile ocular blood flow (POBF), and ocular pulse amplitude (OPA) were measured pre-operatively (baseline) and at 1 week and 3 weeks postoperation in 52 eyes of 26 patients (mean age 63.15±10.25 years) scheduled for unilateral phacoemulsification cataract surgery with intraocular lens implantation. In all of the eyes, a blood flow analyzer (Paradigm DICON; Paradigm Medical Industries Inc.; USA) was used to obtain measurements of IOP, POBF, and OPA. The data obtained from operated eyes were compared statistically to untreated fellow phakic eyes of the patients. RESULTS For operated eyes, the mean baseline IOP, POBF, and OPA values were 15.9±4.64mmHg, 17.41±4.84µL/s, and 2.91±1.12mmHg, respectively. The IOP, POBF, and OPA values were 17.19±4.34mmHg, 17.56±6.46µL/s, and 3.12±1.1mmHg, respectively, in the nonoperated control eyes. Statistically significant differences from baseline measurements were not observed 1 week and 3 weeks postoperation for the operated or nonoperated eyes. There were also no statistically significant differences in any measurements between the operated and nonoperated eyes in all the examination periods (P>0.05 for all). CONCLUSION Uncomplicated phacoemulsification surgery does not affect ocular hemodynamics in normotensive eyes with cataracts. PMID:23991393

  15. Large eddy simulation of powered Fontan hemodynamics.

    PubMed

    Delorme, Y; Anupindi, K; Kerlo, A E; Shetty, D; Rodefeld, M; Chen, J; Frankel, S

    2013-01-18

    Children born with univentricular heart disease typically must undergo three open heart surgeries within the first 2-3 years of life to eventually establish the Fontan circulation. In that case the single working ventricle pumps oxygenated blood to the body and blood returns to the lungs flowing passively through the Total Cavopulmonary Connection (TCPC) rather than being actively pumped by a subpulmonary ventricle. The TCPC is a direct surgical connection between the superior and inferior vena cava and the left and right pulmonary arteries. We have postulated that a mechanical pump inserted into this circulation providing a 3-5 mmHg pressure augmentation will reestablish bi-ventricular physiology serving as a bridge-to-recovery, bridge-to-transplant or destination therapy as a "biventricular Fontan" circulation. The Viscous Impeller Pump (VIP) has been proposed by our group as such an assist device. It is situated in the center of the 4-way TCPC intersection and spins pulling blood from the vena cavae and pushing it into the pulmonary arteries. We hypothesized that Large Eddy Simulation (LES) using high-order numerical methods are needed to capture unsteady powered and unpowered Fontan hemodynamics. Inclusion of a mechanical pump into the CFD further complicates matters due to the need to account for rotating machinery. In this study, we focus on predictions from an in-house high-order LES code (WenoHemo(TM)) for unpowered and VIP-powered idealized TCPC hemodynamics with quantitative comparisons to Stereoscopic Particle Imaging Velocimetry (SPIV) measurements. Results are presented for both instantaneous flow structures and statistical data. Simulations show good qualitative and quantitative agreement with measured data. PMID:23177085

  16. Large Eddy Simulation of Powered Fontan Hemodynamics

    PubMed Central

    Delorme, Y.; Anupindi, K.; Kerlo, A.E.; Shetty, D.; Rodefeld, M.; Chen, J.; Frankel, S.

    2012-01-01

    Children born with univentricular heart disease typically must undergo three open heart surgeries within the first 2–3 years of life to eventually establish the Fontan circulation. In that case the single working ventricle pumps oxygenated blood to the body and blood returns to the lungs flowing passively through the Total Cavopulmonary Connection (TCPC) rather than being actively pumped by a subpulmonary ventricle. The TCPC is a direct surgical connection between the superior and inferior vena cava and the left and right pulmonary arteries. We have postulated that a mechanical pump inserted into this circulation providing a 3–5 mmHg pressure augmentation will reestablish bi-ventricular physiology serving as a bridge-to-recovery, bridge-to-transplant or destination therapy as a “biventricular Fontan” circulation. The Viscous Impeller Pump (VIP) has been proposed by our group as such an assist device. It is situated in the center of the 4-way TCPC intersection and spins pulling blood from the vena cavae and pushing it into the pulmonary arteries. We hypothesized that Large Eddy Simulation (LES) using high-order numerical methods are needed to capture unsteady powered and unpowered Fontan hemodynamics. Inclusion of a mechanical pump into the CFD further complicates matters due to the need to account for rotating machinery. In this study, we focus on predictions from an in-house high-order LES code (WenoHemo™) for unpowered and VIP-powered idealized TCPC hemodynamics with quantitative comparisons to Stereoscopic Particle Imaging Velocimetry (SPIV) measurements. Results are presented for both instantaneous flow structures and statistical data. Simulations show good qualitative and quantitative agreement with measured data. PMID:23177085

  17. Time evolution and hemodynamics of cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Sforza, Daniel M.; Putman, Christopher; Tateshima, Satoshi; Viñuela, Fernando; Cebral, Juan

    2011-03-01

    Cerebral aneurysm rupture is a leading cause of hemorrhagic strokes. Because they are being more frequently diagnosed before rupture and the prognosis of subarachnoid hemorrhage is poor, clinicians are often required to judge which aneurysms are prone to progression and rupture. Unfortunately, the processes of aneurysm initiation, growth and rupture are not well understood. Multiple factors associated to these processes have been identified. Our goal is to investigate two of them, arterial hemodynamics (using computational fluid dynamics) and the peri-aneurysmal environment, by studying a group of growing cerebral aneurysms that are followed longitudinally in time. Six patients with unruptured untreated brain aneurysms which exhibited growth during the observation period were selected for the study. Vascular models of each aneurysm at each observation time were constructed from the corresponding computed tomography angiography (CTA) images. Subsequently, models were aligned, and geometrical differences quantified. Blood flow was modeled with the 3D unsteady incompressible Navier-Stokes equation for a Newtonian fluid, and wall shear stress distribution and flow patterns were calculated and visualized. Analysis of the simulations and changes in geometry revealed asymmetric growth patterns and suggests that areas subject to vigorous flows, i.e. relative high wall shear stress and concentrated streamlines patterns; correspond to regions of aneurysm growth. Furthermore, in some cases the geometrical evolution of aneurysms is clearly affected by contacts with bone structures and calcifications in the wall, and as a consequence the hemodynamics is greatly modified. Thus, in these cases the peri-aneurysmal environment must be considered when analyzing aneurysm evolution.

  18. Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

    1998-01-01

    Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 degrees head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 degrees upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alternating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

  19. Spatial quantitative vectorcardiography in aortic stenosis: correlation with hemodynamic findings.

    PubMed

    Talwar, K K; Mohan, J C; Narula, J; Kaul, U; Bhatia, M L

    1988-02-01

    Thirty-four patients with hemodynamically documented valvar aortic stenosis without congestive heart failure were studied by the corrected Frank lead system vectorcardiography, with special emphasis on the angular characteristics of spatial R max to define the severity of the lesion. Spatial QRS-T angle demonstrated a highly significant correlation with the peak left ventricular systolic pressure (r = 0.72, P less than 0.001) and a significant correlation with peak transvalvar aortic gradient (r = 0.49, P less than 0.01). Furthermore, all patients with a QRS-T angle of more than 90 degrees had significant aortic stenosis (TVG greater than or equal to 50 mm Hg). The peak left ventricular systolic pressure and transvalvar aortic gradient also demonstrated a significant negative correlation with azimuth angle (r = -0.36 and -0.34, respectively; P less than 0.05) and a positive correlation with spatial R max magnitude (r = 0.38 and 0.41, respectively; P less than 0.05). There was no correlation between elevation angle of spatial R max and left ventricle systolic pressure or transvalvar aortic gradient. Our study indicates that spatial quantitative vectorcardiographic angular characteristics, particularly spatial QRS-T angle, may be a useful adjunct to other noninvasive techniques to assess the severity of valvar aortic stenosis. PMID:3343071

  20. A Shape Memory Polymer Dialysis Needle Adapter for the Reduction of Hemodynamic Stress within Arteriovenous Grafts

    SciTech Connect

    Ortega, J M; Small, W; Wilson, T S; Benett, W; Loge, J; Maitland, D J

    2006-08-16

    A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by a dialysis needle flow within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. In vitro flow visualization measurements are made within a graft model following delivery and actuation of a prototype shape memory polymer adapter. Vascular access complications resulting from arteriovenous (AV) graft failures account for over $1 billion per year in the health care costs of dialysis patients in the U.S.[1] The primary mode of failure of arteriovenous fistulas (AVF's) and polytetrafluoroethylene (PTFE) grafts is the development of intimal hyperplasia (IH) and the subsequent formation of stenotic lesions, resulting in a graft flow decline. The hemodynamic stresses arising within AVF's and PTFE grafts play an important role in the pathogenesis of IH. Studies have shown that vascular damage can occur in regions where there is flow separation, oscillation, or extreme values of wall shear stress (WSS).[2] Nevaril et al.[3] show that exposure of red blood cells to WSS's on the order of 1500 dynes/cm2 can result in hemolysis. Hemodynamic stress from dialysis needle flow has recently been investigated for the role it plays in graft failure. Using laser Doppler velocimetry measurements, Unnikrishnan et al.[4] show that turbulence intensities are 5-6 times greater in the AV flow when the needle flow is present and that increased levels of turbulence exist for approximately 7-8cm downstream of the needle. Since the AVF or PTFE graft is exposed to these high levels of hemodynamic stress several hours each week during dialysis sessions, it is quite possible that needle flow is an important contributor to vascular access occlusion.[4] We present a method for reducing the hemodynamic stress in an AV graft by tailoring the fluid

  1. Eculizumab as a bridge to immunosuppressive therapy in severe cold agglutinin disease of anti-Pr specificity.

    PubMed

    Shapiro, Roman; Chin-Yee, Ian; Lam, Selay

    2015-11-01

    Severe cold agglutinin disease with hemodynamic compromise requires rapid stabilization of the autoimmune hemolytic anemia as a bridge to the immunosuppressive effect of rituximab. Herein, we describe eculizumab treatment of severe complement-mediated hemolysis in a patient whose hemodynamic status deteriorated in spite of supportive blood transfusions and therapeutic plasma exchange. PMID:26576277

  2. [Impact of aortic stiffness on central hemodynamics and cardiovascular system].

    PubMed

    Bulas, J; Potočárová, M; Filková, M; Simková, A; Murín, J

    2013-06-01

    Arterial stiffness increases as a result of degenerative processes accelerated by aging and many risk factors, namely arterial hypertension. Basic clinical examination reveals increased pulse pressure as its hemodynamic manifestation. The most serious consequence of increased vascular stiffness, which cannot be revealed by clinical examination, is a change of central hemodynamics leading to increased load of left ventricle, left ventricular hypertrophy, diastolic dysfunction and to overall increase of cardiovascular risk. This review aimed to point at some patophysiological mechanisms taking part in the development of vascular stiffness, vascular remodeling and hemodynamic consequences of these changes. This work also gives an overview of noninvasive examination methods and their characteristics enabling to evaluate the local, regional and systemic arterial stiffness and central pulse wave analysis and their meaning for central hemodynamics and heart workload. PMID:23808736

  3. Pulmonary hemodynamic profile in chronic obstructive pulmonary disease

    PubMed Central

    Portillo, Karina; Torralba, Yolanda; Blanco, Isabel; Burgos, Felip; Rodriguez-Roisin, Roberto; Rios, Jose; Roca, Josep; Barberà, Joan A

    2015-01-01

    Introduction Few data are available in regards to the prevalence of pulmonary hypertension (PH) in the broad spectrum of COPD. This study was aimed at assessing the prevalence of PH in a cohort of COPD patients across the severity of airflow limitation, and reporting the hemodynamic characteristics at rest and during exercise. Methods We performed a retrospective analysis on COPD patients who underwent right-heart catheterization in our center with measurements obtained at rest (n=139) and during exercise (n=85). PH was defined as mean pulmonary artery pressure (mPAP) ≥25 mmHg and pulmonary capillary wedge pressure <15 mmHg. Exercise-induced PH (EIPH) was defined by a ratio of ΔmPAP/Δcardiac output >3. Results PH was present in 25 patients (18%). According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, PH prevalence in GOLD 2 was 7% (3 patients); 25% (14 patients) in GOLD 3; and 22% (8 patients) in GOLD 4. Severe PH (mPAP ≥35 mmHg) was identified in four patients (2.8%). Arterial partial oxygen pressure was the outcome most strongly associated with PH (r=−0.29, P<0.001). EIPH was observed in 60 patients (71%) and had a similar prevalence in both GOLD 2 and 3, and was present in all GOLD 4 patients. Patients with PH had lower cardiac index during exercise than patients without PH (5.0±1.2 versus 6.7±1.4 L/min/m2, respectively; P=0.001). Conclusion PH has a similar prevalence in COPD patients with severe and very-severe airflow limitation, being associated with the presence of arterial hypoxemia. In contrast, EIPH is highly prevalent, even in moderate COPD, and might contribute to limiting exercise tolerance. PMID:26203238

  4. Outcome of Acute Graft Rejection Associated with Hemodynamic Compromise in Pediatric Heart Transplant Recipients

    PubMed Central

    Tissot, Cecile; Buckvold, Shannon; Gralla, Jane; Ivy, D. Dunbar; Pietra, Biagio A.; Miyamoto, Shelley D.

    2011-01-01

    We sought to analyze the outcome of hemodynamically significant acute graft rejection in pediatric heart transplant recipients from a single-center experience. Acute graft rejection remains a major cause of morbidity and mortality for patients who undergo orthotopic heart transplantation and has been associated with the severity of the rejection episode. A retrospective review of all children experiencing a hemodynamically significant rejection episode after orthotopic heart transplantation was performed. Fifty-three patients with 54 grafts had 70 rejection episodes requiring intravenous inotropic support. Forty-one percent of these patients required high-dose inotropic support, with the remaining 59% of patients requiring less inotropic support. Overall graft survival to hospital discharge was 41% for patients in the high-dose group compared to 94% in the low-dose group. Six-month graft survival in patients who required high-dose inotropes remained at 41% compared to 44% in the low-dose group. Hemodynamically significant acute graft rejection in pediatric heart transplant recipients is a devastating problem with poor short- and long-term outcomes. Survival to hospital discharge is dismal in patients who require high-dose inotropic support. In contrast, survival to discharge is quite good in patients who require only low-dose inotropic support; however, six-month graft survival in this group is low secondary to a high incidence of graft failure related to worsening or aggressive transplant coronary artery disease. PMID:20963408

  5. Computational Hemodynamics Framework for the Analysis of Cerebral Aneurysms

    PubMed Central

    Mut, Fernando; Löhner, Rainald; Chien, Aichi; Tateshima, Satoshi; Viñuela, Fernando; Putman, Christopher; Cebral, Juan

    2010-01-01

    Assessing the risk of rupture of intracranial aneurysms is important for clinicians because the natural rupture risk can be exceeded by the small but significant risk carried by current treatments. To this end numerous investigators have used image-based computational fluid dynamics models to extract patient-specific hemodynamics information, but there is no consensus on which variables or hemodynamic characteristics are the most important. This paper describes a computational framework to study and characterize the hemodynamic environment of cerebral aneurysms in order to relate it to clinical events such as growth or rupture. In particular, a number of hemodynamic quantities are proposed to describe the most salient features of these hemodynamic environments. Application to a patient population indicates that ruptured aneurysms tend to have concentrated inflows, concentrated wall shear stress distributions, high maximal wall shear stress and smaller viscous dissipation ratios than unruptured aneurysms. Furthermore, these statistical associations are largely unaffected by the choice of physiologic flow conditions. This confirms the notion that hemodynamic information derived from image-based computational models can be used to assess aneurysm rupture risk, to test hypotheses about the mechanisms responsible for aneurysm formation, progression and rupture, and to answer specific clinical questions. PMID:21643491

  6. Computational modeling of cardiac hemodynamics: Current status and future outlook

    NASA Astrophysics Data System (ADS)

    Mittal, Rajat; Seo, Jung Hee; Vedula, Vijay; Choi, Young J.; Liu, Hang; Huang, H. Howie; Jain, Saurabh; Younes, Laurent; Abraham, Theodore; George, Richard T.

    2016-01-01

    The proliferation of four-dimensional imaging technologies, increasing computational speeds, improved simulation algorithms, and the widespread availability of powerful computing platforms is enabling simulations of cardiac hemodynamics with unprecedented speed and fidelity. Since cardiovascular disease is intimately linked to cardiovascular hemodynamics, accurate assessment of the patient's hemodynamic state is critical for the diagnosis and treatment of heart disease. Unfortunately, while a variety of invasive and non-invasive approaches for measuring cardiac hemodynamics are in widespread use, they still only provide an incomplete picture of the hemodynamic state of a patient. In this context, computational modeling of cardiac hemodynamics presents as a powerful non-invasive modality that can fill this information gap, and significantly impact the diagnosis as well as the treatment of cardiac disease. This article reviews the current status of this field as well as the emerging trends and challenges in cardiovascular health, computing, modeling and simulation and that are expected to play a key role in its future development. Some recent advances in modeling and simulations of cardiac flow are described by using examples from our own work as well as the research of other groups.

  7. The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model

    PubMed Central

    Verloop, Willemien L.; Hubens, Lisette E. G.; Spiering, Wilko; Doevendans, Pieter A.; Goldschmeding, Roel; Bleys, Ronald L. A. W.; Voskuil, Michiel

    2015-01-01

    Rationale Recently, the efficacy of renal denervation (RDN) has been debated. It is discussed whether RDN is able to adequately target the renal nerves. Objective We aimed to investigate how effective RDN was by means of functional hemodynamic measurements and nerve damage on histology. Methods and Results We performed hemodynamic measurements in both renal arteries of healthy pigs using a Doppler flow and pressure wire. Subsequently unilateral denervation was performed, followed by repeated bilateral hemodynamic measurements. Pigs were terminated directly after RDN or were followed for 3 weeks or 3 months after the procedure. After termination, both treated and control arteries were prepared for histology to evaluate vascular damage and nerve damage. Directly after RDN, resting renal blood flow tended to increase by 29±67% (P = 0.01). In contrast, renal resistance reserve increased from 1.74 (1.28) to 1.88 (1.17) (P = 0.02) during follow-up. Vascular histopathology showed that most nerves around the treated arteries were located outside the lesion areas (8±7 out of 55±25 (14%) nerves per pig were observed within a lesion area). Subsequently, a correlation was noted between a more impaired adventitia and a reduction in renal resistance reserve (β: -0.33; P = 0.05) at three weeks of follow-up. Conclusion Only a small minority of renal nerves was targeted after RDN. Furthermore, more severe adventitial damage was related to a reduction in renal resistance in the treated arteries at follow-up. These hemodynamic and histological observations may indicate that RDN did not sufficiently target the renal nerves. Potentially, this may explain the significant spread in the response after RDN. PMID:26587981

  8. Can maternal-fetal hemodynamics influence prenatal development in dogs?

    PubMed

    Freitas, Luana Azevedo de; Mota, Gustavo Lobato; Silva, Herlon Victor Rodrigues; Carvalho, Cibele Figueira; Silva, Lúcia Daniel Machado da

    2016-09-01

    The goals of this study were to report embryonic and fetal ultrasound changes and compare blood flow of uteroplacental and umbilical arteries of normal and abnormal conceptus. Accordingly, from the day of mating or artificial insemination, all fetuses in 60 pregnancies were evaluated weekly. According to the ultrasound findings, the gestational age was determined and the conceptuses were divided into normal or abnormal (embryonic and fetal abnormalities). The two-dimensional ultrasound assessment consists of measuring and evaluating the echogenicity of conceptus and extra-fetal structures. Doppler velocimetry measured the resistivity index (RI) and pulsatility index (PI) of uteroplacental and umbilical arteries. Two-dimensional and Doppler measurements were expressed as mean and standard deviation. Differences between normal and abnormal groups were subject to Mann-Whitney test (P<0.05). Of 264 fetuses, 15.90% showed embryonic abnormalities (resorption) and 5.68% presented fetal abnormalities (congenital abnormalities, fetal underdevelopment and fetal death). We observed a reduced diameter and abnormalities in the contour of gestational vesicle, lack of viability, increased placental thickness, increased fluid echogenicity and increases in RI and PI of uteroplacental arteries of conceptuses with embryonic resorption between the 2nd and 4th weeks. Fetuses with abnormalities showed changes in the flow of uteroplacental and umbilical arteries prior to visualization of two-dimensional alterations and different vascular behavior according to the classification of the change. Results show that ultrasound is efficient for the detection of embryonic and fetal abnormalities. When combined with Doppler ultrasound, it allows early detection of gestational changes, as well as hemodynamic changes, in conceptuses with abnormalities, which may influence their development. PMID:27509872

  9. Hemodynamics in coronary arteries with overlapping stents.

    PubMed

    Rikhtegar, Farhad; Wyss, Christophe; Stok, Kathryn S; Poulikakos, Dimos; Müller, Ralph; Kurtcuoglu, Vartan

    2014-01-22

    Coronary artery stenosis is commonly treated by stent placement via percutaneous intervention, at times requiring multiple stents that may overlap. Stent overlap is associated with increased risk of adverse clinical outcome. While changes in local blood flow are suspected to play a role therein, hemodynamics in arteries with overlapping stents remain poorly understood. In this study we analyzed six cases of partially overlapping stents, placed ex vivo in porcine left coronary arteries and compared them to five cases with two non-overlapping stents. The stented vessel geometries were obtained by micro-computed tomography of corrosion casts. Flow and shear stress distribution were calculated using computational fluid dynamics. We observed a significant increase in the relative area exposed to low wall shear stress (WSS<0.5 Pa) in the overlapping stent segments compared both to areas without overlap in the same samples, as well as to non-overlapping stents. We further observed that the configuration of the overlapping stent struts relative to each other influenced the size of the low WSS area: positioning of the struts in the same axial location led to larger areas of low WSS compared to alternating struts. Our results indicate that the overlap geometry is by itself sufficient to cause unfavorable flow conditions that may worsen clinical outcome. While stent overlap cannot always be avoided, improved deployment strategies or stent designs could reduce the low WSS burden. PMID:24275438

  10. Wireless Monitoring of Liver Hemodynamics In Vivo

    SciTech Connect

    Akl, Tony; Wilson, Mark A.; Ericson, Milton Nance; Farquhar, Ethan; Cote, Gerard L.

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics.

  11. Hemodynamics of Curved Vessels with Stenosis

    NASA Astrophysics Data System (ADS)

    Boghosian, Michael E.; Cassel, Kevin W.

    2007-11-01

    In hemodialysis access, the brachiocephalic or upper-arm fistula has less than optimal functional rates. The cause of this reduced patency is stenosis due to intimal hyperplasia in the cephalic vein. Stenosis typically leads to thrombosis and ultimately failure of the fistula. To increase our understanding of this process, numerical simulations of the unsteady, two-dimensional, incompressible Navier-Stokes equations are solved for the flow in an infinite channel having curvature and stenosis. Physiologically relevant Reynolds numbers ranging from 300 to 1500 and stenosis percentages of 0, 25, 50, and 75 are modeled. The post-stenotic flow is characterized by strong shear layers and recirculation regions. The largest shear stresses are found just upstream of the stenosis apex. The maximum shear stress increases with increasing Reynolds number and percent stenosis. The results indicate that hemodynamic conditions in the vein after fistula creation combined with curvature of the cephalic arch lead to shear stresses that exceed normal physiological values (both minimum and maximum). In some cases, the shear stresses are sufficiently large to cause damage to the endothelium and possibly denudation.

  12. 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.

  13. Numerical predictions of hemodynamics following surgeries in cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Rayz, Vitaliy; Lawton, Michael; Boussel, Loic; Leach, Joseph; Acevedo, Gabriel; Halbach, Van; Saloner, David

    2014-11-01

    Large cerebral aneurysms present a danger of rupture or brain compression. In some cases, clinicians may attempt to change the pathological hemodynamics in order to inhibit disease progression. This can be achieved by changing the vascular geometry with an open surgery or by deploying a stent-like flow diverter device. Patient-specific CFD models can help evaluate treatment options by predicting flow regions that are likely to become occupied by thrombus (clot) following the procedure. In this study, alternative flow scenarios were modeled for several patients who underwent surgical treatment. Patient-specific geometries and flow boundary conditions were obtained from magnetic resonance angiography and velocimetry data. The Navier-Stokes equations were solved with a finite volume solver Fluent. A porous media approach was used to model flow-diverter devices. The advection-diffusion equation was solved in order to simulate contrast agent transport and the results were used to evaluate flow residence time changes. Thrombus layering was predicted in regions characterized by reduced velocities and shear stresses as well as increased flow residence time. The simulations indicated surgical options that could result in occlusion of vital arteries with thrombus. Numerical results were compared to experimental and clinical MRI data. The results demonstrate that image-based CFD models may help improve the outcome of surgeries in cerebral aneurysms. acknowledge R01HL115267.

  14. Hemodynamic monitoring in the intensive care unit: a Brazilian perspective

    PubMed Central

    Dias, Fernando Suparregui; Rezende, Ederlon Alves de Carvalho; Mendes, Ciro Leite; Silva Jr., João Manoel; Sanches, Joel Lyra

    2014-01-01

    Objective In Brazil, there are no data on the preferences of intensivists regarding hemodynamic monitoring methods. The present study aimed to identify the methods used by national intensivists, the hemodynamic variables they consider important, the regional differences, the reasons for choosing a particular method, and the use of protocols and continued training. Methods National intensivists were invited to answer an electronic questionnaire during three intensive care events and later, through the Associação de Medicina Intensiva Brasileira portal, between March and October 2009. Demographic data and aspects related to the respondent preferences regarding hemodynamic monitoring were researched. Results In total, 211 professionals answered the questionnaire. Private hospitals showed higher availability of resources for hemodynamic monitoring than did public institutions. The pulmonary artery catheter was considered the most trusted by 56.9% of the respondents, followed by echocardiograms, at 22.3%. Cardiac output was considered the most important variable. Other variables also considered relevant were mixed/central venous oxygen saturation, pulmonary artery occlusion pressure, and right ventricular end-diastolic volume. Echocardiography was the most used method (64.5%), followed by pulmonary artery catheter (49.3%). Only half of respondents used treatment protocols, and 25% worked in continuing education programs in hemodynamic monitoring. Conclusion Hemodynamic monitoring has a greater availability in intensive care units of private institutions in Brazil. Echocardiography was the most used monitoring method, but the pulmonary artery catheter remains the most reliable. The implementation of treatment protocols and continuing education programs in hemodynamic monitoring in Brazil is still insufficient. PMID:25607264

  15. Multi-analyte profile analysis of plasma immune proteins: altered expression of peripheral immune factors is associated with neuropsychiatric symptom severity in adults with and without chronic hepatitis C virus infection.

    PubMed

    Huckans, Marilyn; Fuller, Bret E; Olavarria, Hannah; Sasaki, Anna W; Chang, Michael; Flora, Kenneth D; Kolessar, Michael; Kriz, Daniel; Anderson, Jeanne R; Vandenbark, Arthur A; Loftis, Jennifer M

    2014-03-01

    BackgroundThe purpose of this study was to characterize hepatitis C virus (HCV)-associated differences in the expression of 47 inflammatory factors and to evaluate the potential role of peripheral immune activation in HCV-associated neuropsychiatric symptoms-depression, anxiety, fatigue, and pain. An additional objective was to evaluate the role of immune factor dysregulation in the expression of specific neuropsychiatric symptoms to identify biomarkers that may be relevant to the treatment of these neuropsychiatric symptoms in adults with or without HCV. MethodsBlood samples and neuropsychiatric symptom severity scales were collected from HCV-infected adults (HCV+, n = 39) and demographically similar noninfected controls (HCV-, n = 40). Multi-analyte profile analysis was used to evaluate plasma biomarkers. ResultsCompared with HCV- controls, HCV+ adults reported significantly (P < 0.050) greater depression, anxiety, fatigue, and pain, and they were more likely to present with an increased inflammatory profile as indicated by significantly higher plasma levels of 40% (19/47) of the factors assessed (21%, after correcting for multiple comparisons). Within the HCV+ group, but not within the HCV- group, an increased inflammatory profile (indicated by the number of immune factors > the LDC) significantly correlated with depression, anxiety, and pain. Within the total sample, neuropsychiatric symptom severity was significantly predicted by protein signatures consisting of 4-10 plasma immune factors; protein signatures significantly accounted for 19-40% of the variance in depression, anxiety, fatigue, and pain. ConclusionsOverall, the results demonstrate that altered expression of a network of plasma immune factors contributes to neuropsychiatric symptom severity. These findings offer new biomarkers to potentially facilitate pharmacotherapeutic development and to increase our understanding of the molecular pathways associated with neuropsychiatric symptoms in

  16. Multi-analyte profile analysis of plasma immune proteins: altered expression of peripheral immune factors is associated with neuropsychiatric symptom severity in adults with and without chronic hepatitis C virus infection

    PubMed Central

    Huckans, Marilyn; Fuller, Bret E; Olavarria, Hannah; Sasaki, Anna W; Chang, Michael; Flora, Kenneth D; Kolessar, Michael; Kriz, Daniel; Anderson, Jeanne R; Vandenbark, Arthur A; Loftis, Jennifer M

    2014-01-01

    Background The purpose of this study was to characterize hepatitis C virus (HCV)-associated differences in the expression of 47 inflammatory factors and to evaluate the potential role of peripheral immune activation in HCV-associated neuropsychiatric symptoms—depression, anxiety, fatigue, and pain. An additional objective was to evaluate the role of immune factor dysregulation in the expression of specific neuropsychiatric symptoms to identify biomarkers that may be relevant to the treatment of these neuropsychiatric symptoms in adults with or without HCV. Methods Blood samples and neuropsychiatric symptom severity scales were collected from HCV-infected adults (HCV+, n = 39) and demographically similar noninfected controls (HCV−, n = 40). Multi-analyte profile analysis was used to evaluate plasma biomarkers. Results Compared with HCV− controls, HCV+ adults reported significantly (P < 0.050) greater depression, anxiety, fatigue, and pain, and they were more likely to present with an increased inflammatory profile as indicated by significantly higher plasma levels of 40% (19/47) of the factors assessed (21%, after correcting for multiple comparisons). Within the HCV+ group, but not within the HCV− group, an increased inflammatory profile (indicated by the number of immune factors > the LDC) significantly correlated with depression, anxiety, and pain. Within the total sample, neuropsychiatric symptom severity was significantly predicted by protein signatures consisting of 4–10 plasma immune factors; protein signatures significantly accounted for 19–40% of the variance in depression, anxiety, fatigue, and pain. Conclusions Overall, the results demonstrate that altered expression of a network of plasma immune factors contributes to neuropsychiatric symptom severity. These findings offer new biomarkers to potentially facilitate pharmacotherapeutic development and to increase our understanding of the molecular pathways associated with neuropsychiatric

  17. Effects of Type II diabetes on capillary hemodynamics in skeletal muscle.

    PubMed

    Padilla, Danielle J; McDonough, Paul; Behnke, Brad J; Kano, Yutaka; Hageman, K Sue; Musch, Timothy I; Poole, David C

    2006-11-01

    Microcirculatory red blood cell (RBC) hemodynamics are impaired within skeletal muscle of Type I diabetic rats (Kindig CA, Sexton WL, Fedde MR, and Poole DC. Respir Physiol 111: 163-175, 1998). Whether muscle microcirculatory dysfunction occurs in Type II diabetes, the more prevalent form of the disease, is unknown. We hypothesized that Type II diabetes would reduce the proportion of capillaries supporting continuous RBC flow and RBC hemodynamics within the spinotrapezius muscle of the Goto-Kakizaki Type II diabetic rat (GK). With the use of intravital microscopy, muscle capillary diameter (d(c)), capillary lineal density, capillary tube hematocrit (Hct(cap)), RBC flux (F(RBC)), and velocity (V(RBC)) were measured in healthy male Wistar (control: n = 5, blood glucose, 105 +/- 5 mg/dl) and male GK (n = 7, blood glucose, 263 +/- 34 mg/dl) rats under resting conditions. Mean arterial pressure did not differ between groups (P > 0.05). Sarcomere length was set to a physiological length ( approximately 2.7 mum) to ensure that muscle stretching did not alter capillary hemodynamics; d(c) was not different between control and GK rats (P > 0.05), but the percentage of RBC-perfused capillaries (control: 93 +/- 3; GK: 66 +/- 5 %), Hct(cap), V(RBC), F(RBC), and O(2) delivery per unit of muscle were all decreased in GK rats (P < 0.05). This study indicates that Type II diabetes reduces both convective O(2) delivery and diffusive O(2) transport properties within muscle microcirculation. If these microcirculatory deficits are present during exercise, it may provide a basis for the reduced O(2) exchange characteristic of Type II diabetic patients. PMID:16844923

  18. Hemodynamics of left internal mammary artery bypass graft: Effect of anastomotic geometry, coronary artery stenosis, and postoperative time.

    PubMed

    Fan, Tingting; Lu, Yuan; Gao, Yan; Meng, Jie; Tan, Wenchang; Huo, Yunlong; Kassab, Ghassan S

    2016-03-21

    Although the left internal mammary artery (LIMA) bypass graft is the best choice for surgical revascularization, its hemodynamics are still complex and can result in long-term graft failure. Here, we performed a hemodynamic analysis of the LIMA-coronary artery with end-to-side/side-to-side anastomoses based on 15 patient-specific CTA images at various postoperative periods. We hypothesize that hemodynamic patterns are determined by the interplay of LIMA geometry, anastomotic configuration, and severity of native coronary artery stenosis, which are strongly affected by the postoperative time. A 3D finite volume method with the inlet pressure wave and outlet resistance boundary conditions was used to compute the distribution of pressure and flow, from which the time-averaged wall shear stress (TAWSS), oscillation shear index (OSI), time-averaged WSS gradient (TAWSSG), and transverse WSS (transWSS) were determined. To characterize the hemodynamic environment, we defined surface area ratios of low TAWSS (≤4dynes/cm(2)), high OSI (≥0.15), TAWSSG (≥500dynes/cm(3)), and transWSS (≥6dynes/cm(2)) in the LIMA graft and at the anastomosis between LIMA graft and coronary artery. These ratios were determined by the interplay of multiple morphometric parameters in the LIMA-coronary artery, but increased with postoperative time. These findings have significant implications for understanding LIMA graft patency. PMID:26900034

  19. Cerebral hemodynamics during graded Valsalva maneuvers

    PubMed Central

    Perry, Blake G.; Cotter, James D.; Mejuto, Gaizka; Mündel, Toby; Lucas, Samuel J. E.

    2014-01-01

    The Valsalva maneuver (VM) produces large and abrupt changes in mean arterial pressure (MAP) that challenge cerebral blood flow and oxygenation. We examined the effect of VM intensity on middle cerebral artery blood velocity (MCAv) and cortical oxygenation responses during (phases I–III) and following (phase IV) a VM. Healthy participants (n = 20 mean ± SD: 27 ± 7 years) completed 30 and 90% of their maximal VM mouth pressure for 10 s (order randomized) whilst standing. Beat-to-beat MCAv, cerebral oxygenation (NIRS) and MAP across the different phases of the VM are reported as the difference from standing baseline. There were significant interaction (phase * intensity) effects for MCAv, total oxygenation index (TOI) and MAP (all P < 0.01). MCAv decreased during phases II and III (P < 0.01), with the greatest decrease during phase III (−5 ± 8 and −19 ± 15 cm·s−1 for 30 and 90% VM, respectively). This pattern was also evident in TOI (phase III: −1 ± 1 and −5 ± 4%, both P < 0.05). Phase IV increased MCAv (22 ± 15 and 34 ± 23 cm·s−1), MAP (15 ± 14 and 24 ± 17 mm Hg) and TOI (5 ± 6 and 7 ± 5%) relative to baseline (all P < 0.05). Cerebral autoregulation, indexed, as the %MCAv/%MAP ratio, showed a phase effect only (P < 0.001), with the least regulation during phase IV (2.4 ± 3.0 and 3.2 ± 2.9). These data illustrate that an intense VM profoundly affects cerebral hemodynamics, with a reactive hyperemia occurring during phase IV following modest ischemia during phases II and III. PMID:25309449

  20. Wireless monitoring of liver hemodynamics in vivo.

    PubMed

    Akl, Tony J; Wilson, Mark A; Ericson, M Nance; Farquhar, Ethan; Coté, Gerard L

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics. PMID:25019160

  1. Wireless Monitoring of Liver Hemodynamics In Vivo

    PubMed Central

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Farquhar, Ethan; Coté, Gerard L.

    2014-01-01

    Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics. PMID:25019160

  2. Acute hemodynamic responses to weightlessness in humans

    NASA Technical Reports Server (NTRS)

    Lathers, C. M.; Charles, J. B.; Elton, K. F.; Holt, T. A.; Mukai, C.; Bennett, B. S.; Bungo, M. W.

    1989-01-01

    As NASA designs space flights requiring prolonged periods of weightlessness for a broader segment of the population, it will be important to know the acute and sustained effects of weightlessness on the cardiovascular system since this information will contribute to understanding of the clinical pharmacology of drugs administered in space. Due to operational constraints on space flights, earliest effects of weightlessness have not been documented. We examined hemodynamic responses of humans to transitions from acceleration to weightlessness during parabolic flight on NASA's KC-135 aircraft. Impedance cardiography data were collected over four sets of 8-10 parabolas, with a brief rest period between sets. Each parabola included a period of 1.8 Gz, then approximately 20 seconds of weightlessness, and finally a period of 1.6 Gz; the cycle repeated almost immediately for the remainder of the set. Subjects were semi-supine (Shuttle launch posture) for the first set, then randomly supine, sitting and standing for each subsequent set. Transition to weightlessness while standing produced decreased heart rate, increased thoracic fluid content, and increased stroke index. Surprisingly, the onset of weightlessness in the semi-supine posture produced little evidence of a headward fluid shift. Heart rate, stroke index, and cardiac index are virtually unchanged after 20 seconds of weightlessness, and thoracic fluid content is slightly decreased. Semi-supine responses run counter to Shuttle crewmember reports of noticeable fluid shift after minutes to hours in orbit. Apparently, the headward fluid shift commences in the semi-supine posture before launch. is augmented by launch acceleration, but briefly interrupted immediately in orbit, then resumes and is completed over the next hours.

  3. Acute hemodynamic responses to weightlessness in humans.

    PubMed

    Lathers, C M; Charles, J B; Elton, K F; Holt, T A; Mukai, C; Bennett, B S; Bungo, M W

    1989-07-01

    As NASA designs space flights requiring prolonged periods of weightlessness for a broader segment of the population, it will be important to know the acute and sustained effects of weightlessness on the cardiovascular system since this information will contribute to understanding of the clinical pharmacology of drugs administered in space. Due to operational constraints on space flights, earliest effects of weightlessness have not been documented. We examined hemodynamic responses of humans to transitions from acceleration to weightlessness during parabolic flight on NASA's KC-135 aircraft. Impedance cardiography data were collected over four sets of 8-10 parabolas, with a brief rest period between sets. Each parabola included a period of 1.8 Gz, then approximately 20 seconds of weightlessness, and finally a period of 1.6 Gz; the cycle repeated almost immediately for the remainder of the set. Subjects were semi-supine (Shuttle launch posture) for the first set, then randomly supine, sitting and standing for each subsequent set. Transition to weightlessness while standing produced decreased heart rate, increased thoracic fluid content, and increased stroke index. Surprisingly, the onset of weightlessness in the semi-supine posture produced little evidence of a headward fluid shift. Heart rate, stroke index, and cardiac index are virtually unchanged after 20 seconds of weightlessness, and thoracic fluid content is slightly decreased. Semi-supine responses run counter to Shuttle crewmember reports of noticeable fluid shift after minutes to hours in orbit. Apparently, the headward fluid shift commences in the semi-supine posture before launch. is augmented by launch acceleration, but briefly interrupted immediately in orbit, then resumes and is completed over the next hours. PMID:2760255

  4. Hemodynamic Energy Dissipation in the Cardiovascular System: Generalized Theoretical Analysis on Disease States

    PubMed Central

    Dasi, Lakshmi P.; Pekkan, Kerem; de Zelicourt, Diane; Sundareswaran, Kartik S.; Krishnankutty, Resmi; Delnido, Pedro J.; Yoganathan, Ajit P.

    2010-01-01

    Background We present a fundamental theoretical framework for analysis of energy dissipation in any component of the circulatory system and formulate the full energy budget for both venous and arterial circulations. New indices allowing disease-specific subject-to-subject comparisons and disease-to-disease hemodynamic evaluation (quantifying the hemodynamic severity of one vascular disease type to the other) are presented based on this formalism. Methods and Results Dimensional analysis of energy dissipation rate with respect to the human circulation shows that the rate of energy dissipation is inversely proportional to the square of the patient body surface area and directly proportional to the cube of cardiac output. This result verified the established formulae for energy loss in aortic stenosis that was solely derived through empirical clinical experience. Three new indices are introduced to evaluate more complex disease states: (1) circulation energy dissipation index (CEDI), (2) aortic valve energy dissipation index (AV-EDI), and (3) total cavopulmonary connection energy dissipation index (TCPCEDI). CEDI is based on the full energy budget of the circulation and is the proper measure of the work performed by the ventricle relative to the net energy spent in overcoming frictional forces. It is shown to be 4.01 ± 0.16 for healthy individuals and above 7.0 for patients with severe aortic stenosis. Application of CEDI index on single-ventricle venous physiology reveals that the surgically created Fontan circulation, which is indeed palliative, progressively degrades in hemodynamic efficiency with growth (p <0.001), with the net dissipation in a typical Fontan patient (Body surface area = 1.0 m2) being equivalent to that of an average case of severe aortic stenosis. AV-EDI is shown to be the proper index to gauge the hemodynamic severity of stenosed aortic valves as it accurately reflects energy loss. It is about 0.28 ± 0.12 for healthy human valves. Moderate

  5. Hemodynamic monitoring and outcome-a physiological appraisal.

    PubMed

    Chan, Yoo-Kuen; Khan, Zahid Hussain

    2011-12-01

    Hemodynamic monitoring provides us with refined details about the cardiovascular system. In spite of increased availability of the monitoring process and monitoring equipment, hemodynamic monitoring has not significantly improved survival outcome. Care providers should be cognizant of the role of the cardiovascular system and its importance in oxygen delivery to the cells in order to sustain life. Effective hemodynamic monitoring should be able to delineate how well the system is performing in carrying out this role. Different hemodynamic monitors serve in this role to a different extent; some provide very little information on this. The cardiovascular system is only one of the many systems that need to function optimally for survival; others of equal importance include the integrity of the airway, the breathing process, the adequacy of hemoglobin level, and the health of the tissue bed, especially in the brain and the heart. Advances in hemodynamic monitoring with focus on oxygen delivery at the cellular level may ultimately provide the edge to effective monitoring that can impact outcome. PMID:22221689

  6. The effect of stress hormones on cerebral hemodynamics in patients with chronic posttraumatic stress disorder.

    PubMed

    Dikanović, Marinko; Kadojić, Dragutin; Demarin, Vida; Trkanjec, Zlatko; Mihaljević, Ivan; Bitunjac, Milan; Kadojić, Mira; Matić, Ivo; Sapina, Lidija; Vuletić, Vladimir; Cengić, Ljiljana

    2009-09-01

    The aim of the study was to assess the possible correlation between catecholamine and cortisol levels and changes in cerebral hemodynamics in patients with chronic posttraumatic stress disorder (PTSD). The study included 50 patients with chronic PTSD first ever hospitalized for psychiatric treatment and 50 healthy control subjects. All study subjects were aged 30-50. In PTSD patients, 24-h urine levels of the epinephrine and norepinephrine metabolites vanillylmandelic acid (VMA) and cortisol were determined and transcranial Doppler ultrasonography was performed on day 1 of hospital stay and repeated after 21-day psychiatric medicamentous treatment. On initial testing, increased level of 24-h VMA, decreased cortisol level and elevated mean blood flow velocity (MBFV) in the circle of Willis vessels were recorded in 25 (50.00%) patients. Repeat findings obtained after 21-day psychopharmaceutical therapy showed increased 24-h VMA, decreased cortisol and elevated MBFV in the circle of Willis vessels in seven (14.00%) patients (initial vs. repeat testing, P = 0.0002). Such parameters were not recorded in any of the control subjects (initial PTSD patient testing vs. control group, P = 0.0000). Study results pointed to a significant correlation between increased catecholamine levels, decreased cortisol level and elevated MBFV in the circle of Willis vessels caused by cerebral vasospasm. Psychiatric medicamentous therapy administered for three weeks significantly reduced the proportion of patients with concurrently altered cerebral hemodynamics, increased levels of catecholamine metabolites and decreased level of cortisol. PMID:20405635

  7. Hemodynamic monitoring and care of the patient of high risk for anesthesia.

    PubMed Central

    Pietak, S P; Teasdale, S J

    1979-01-01

    Hemodynamic monitoring and care of the patient at high risk for anesthesia require a careful and systematic approach. During preoperative evaluation the patient at increased risk must be identified and correctable problems must be solved. The patient's current medications must be reviewed because they may influence the choice of anesthetic approach and may alter the physiologic response to the stresses commonly associated with anesthesia. In addition to conventional clinical and electrocardiographic monitoring, perioperative hemodynamic monitoring may be desirable for patients at special risk, who are likely to have significant associated medical problems or to undergo complicated surgical procedures. No ideal induction agent exists, and hypotension secondary to peripheral vasodilation or myocardial depression, or both, is a potential problem. Patients with an inordinately high risk may benefit from mechanical circulatory assistance prior to induction of anesthesia. Attention to oxygenation, blood volume replacement and the prevention of hypertensive episodes are particularly important during anesthesia so that optimal cardiac performance is ensured and ischemia avoided. The stresses during emergence from anesthesia contribute to lability of the cardiovascular status and hypoxemia. The period of risk does not conclude with immediate recovery from anesthesia but extends through the postoperative phase. Careful monitoring and attention to the control of pain, prevention of hypotension and hypertension, adequate oxygenation, early mobilization and resumption of the administration of cardiac medications are important factors in a successful outcome. PMID:497983

  8. Mining data from hemodynamic simulations for generating prediction and explanation models.

    PubMed

    Bosnić, Zoran; Vračar, Petar; Radović, Milos D; Devedžić, Goran; Filipović, Nenad D; Kononenko, Igor

    2012-03-01

    One of the most common causes of human death is stroke, which can be caused by carotid bifurcation stenosis. In our work, we aim at proposing a prototype of a medical expert system that could significantly aid medical experts to detect hemodynamic abnormalities (increased artery wall shear stress). Based on the acquired simulated data, we apply several methodologies for1) predicting magnitudes and locations of maximum wall shear stress in the artery, 2) estimating reliability of computed predictions, and 3) providing user-friendly explanation of the model's decision. The obtained results indicate that the evaluated methodologies can provide a useful tool for the given problem domain. PMID:21846607

  9. Relationship Between Hemodynamically Significant Ductus Arteriosus and Ischemia-Modified Albumin in Premature Infants.

    PubMed

    Kahveci, Hasan; Tayman, Cüneyt; Laloğlu, Fuat; Kavas, Nazan; Ciftel, Murat; Yılmaz, Osman; Laloğlu, Esra; Erdil, Abdulah; Aksoy, Hülya; Aydemir, Salih

    2016-04-01

    Hemodynamically significant ductus arteriosus (hsPDA) may alter organ perfusion by interfering blood flow to the tissues. Therefore, in infants with hsPDA, hypoxia occurs in many tissues. In this study, we aimed to investigate the diagnostic significance of serum (ischemia-modified albumin) IMA levels as a screening tool for hsPDA, and its relation to the severity of the disease in the preterm neonates. For this purpose, seventy-two premature infants with gestation age <34 weeks were included in the study. Thirty premature infants with hsPDA were assigned as the study group and 42 premature infants without PDA were determined as the control group. Blood samples were collected before the treatment and 24 h after the treatment, and analyzed for IMA levels. IMA levels in the study group (1.26 ± 0.36 ABSU) were found to be significantly higher than control group (0.65 ± 0.12 ABSU) (p < 0.05). In infants with hsPDA, a positive correlation was found between IMA and PDA diameter (ρ = 0.876, p = 0.022), and LA/Ao ratio (ρ = 0.863, p = 0.014). The cut-off value of IMA for hsPDA was measured as 0.78 ABSU with 88.89 % sensitivity, and 90.24 % specificity, 85.71 % positive predictive, 92.5 % negative predictive value [area under the curve (AUC) = 0.96; p < 0.001]. The mean IMA value of the infants with hsPDA before treatment was 1.26 ± 0.36 ABSU, and the mean IMA value of infants after medical treatment was 0.67 ± 0.27 ABSU (p = 0.03). We concluded that IMA can be used as a marker for the diagnosis and monitoring of a successful treatment of hsPDA. PMID:27069332

  10. Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans

    PubMed Central

    Gilmartin, Geoffrey S.; Tamisier, Renaud; Curley, Matthew; Weiss, J. Woodrow

    2008-01-01

    Recurrent and intermittent nocturnal hypoxia is characteristic of several diseases including chronic obstructive pulmonary disease, congestive heart failure, obesity-hypoventilation syndrome, and obstructive sleep apnea. The contribution of hypoxia to cardiovascular morbidity and mortality in these disease states is unclear, however. To investigate the impact of recurrent nocturnal hypoxia on hemodynamics, sympathetic activity, and vascular tone we evaluated 10 normal volunteers before and after 14 nights of nocturnal sustained hypoxia (mean oxygen saturation 84.2%, 9 h/night). Over the exposure, subjects exhibited ventilatory acclimatization to hypoxia as evidenced by an increase in resting ventilation (arterial Pco2 41.8 ± 1.5 vs. 37.5 ± 1.3 mmHg, mean ± SD; P < 0.05) and in the isocapnic hypoxic ventilatory response (slope 0.49 ± 0.1 vs. 1.32 ± 0.2 l/min per 1% fall in saturation; P < 0.05). Subjects exhibited a significant increase in mean arterial pressure (86.7 ± 6.1 vs. 90.5 ± 7.6 mmHg; P < 0.001), muscle sympathetic nerve activity (20.8 ± 2.8 vs. 28.2 ± 3.3 bursts/min; P < 0.01), and forearm vascular resistance (39.6 ± 3.5 vs. 47.5 ± 4.8 mmHg·ml−1·100 g tissue·min; P < 0.05). Forearm blood flow during acute isocapnic hypoxia was increased after exposure but during selective brachial intra-arterial vascular infusion of the alpha-blocker phentolamine it was unchanged after exposure. Finally, there was a decrease in reactive hyperemia to 15 min of forearm ischemia after the hypoxic exposure. Recurrent nocturnal hypoxia thus increases sympathetic activity and alters peripheral vascular tone. These changes may contribute to the increased cardiovascular and cerebrovascular risk associated with clinical diseases that are associated with chronic recurrent hypoxia. PMID:18539753

  11. A Revised Hemodynamic Theory of Age-Related Macular Degeneration.

    PubMed

    Gelfand, Bradley D; Ambati, Jayakrishna

    2016-08-01

    Age-related macular degeneration (AMD) afflicts one out of every 40 individuals worldwide, causing irreversible central blindness in millions. The transformation of various tissue layers within the macula in the retina has led to competing conceptual models of the molecular pathways, cell types, and tissues responsible for the onset and progression of AMD. A model that has persisted for over 6 decades is the hemodynamic, or vascular theory of AMD progression, which states that vascular dysfunction of the choroid underlies AMD pathogenesis. Here, we re-evaluate this hypothesis in light of recent advances on molecular, anatomic, and hemodynamic changes underlying choroidal dysfunction in AMD. We propose an updated, detailed model of hemodynamic dysfunction as a mechanism of AMD development and progression. PMID:27423265

  12. Image-Based Evaluation of Vascular Function and Hemodynamics

    PubMed Central

    Lee, Jongmin

    2013-01-01

    The noticeable characteristics of the blood vascular structure are the inconsistent viscosity of blood and the stiffness of the vascular wall. If we can control these two factors, we can solve more problems related to hemodynamics and vascular wall function. Understanding the properties of hemodynamics and vascular wall function may provide more information applicable to clinical practice for cardiovascular disease. The bedside techniques evaluating vascular function usually measure indirect parameters. In contrast, some medical imaging techniques provide clear and direct depictions of functional cardiovascular characteristics. In this review, image-based evaluation of hemodynamic and vascular wall functions is discussed from the perspective of blood flow velocity, flow volume, flow pattern, peripheral vascular resistance, intraluminal pressure, vascular wall stress, and wall stiffness. PMID:26587430

  13. Influence of vascular function and pulsatile hemodynamics on cardiac function.

    PubMed

    Bell, Vanessa; Mitchell, Gary F

    2015-09-01

    Interactions between cardiac and vascular structure and function normally are optimized to ensure delivery of cardiac output with modest pulsatile hemodynamic overhead. Aortic stiffening with age or disease impairs optimal ventricular-vascular coupling, increases pulsatile load, and contributes to left ventricular (LV) hypertrophy, reduced systolic function, and impaired diastolic relaxation. Aortic pulse pressure and timing of peak systolic pressure are well-known measures of hemodynamic ventricular-vascular interaction. Recent work has elucidated the importance of direct, mechanical coupling between the aorta and the heart. LV systolic contraction results in displacement of aortic and mitral annuli, thereby producing longitudinal stretch in the ascending aorta and left atrium, respectively. Force associated with longitudinal stretch increases systolic load on the LV. However, the resulting energy stored in the elastic elements of the proximal aorta during systole facilitates early diastolic LV recoil and rapid filling. This review discusses current views on hemodynamics and mechanics of ventricular-vascular coupling. PMID:26164466

  14. Upper extremity hemodynamics and sensation with backpack loads.

    PubMed

    Kim, Sae Hoon; Neuschwander, Timothy B; Macias, Brandon R; Bachman, Larry; Hargens, Alan R

    2014-05-01

    Heavy backpacks are often used in extreme environments, for example by military during combat, therefore completion of tasks quickly and efficiently is of operational relevance. The purpose of this study was to quantify hemodynamic parameters (brachial artery Doppler and microvascular flow by photoplethysmography; tissue oxygenation by near-infrared spectroscopy; arterial oxygen saturation by pulse oximeter) and sensation in upper extremities and hands (Semmes-Weinstein monofilament test and 2-point discrimination test) while wearing a loaded backpack (12 kg) in healthy adults for 10 min. All values were compared to baseline before wearing a backpack. Moderate weight loaded backpack loads significantly decreased upper extremity sensation as well as all macrovascular and microvascular hemodynamic values. Decreased macrovascular and microvascular hemodynamics may produce neurological dysfunction and consequently, probably affect fine motor control of the hands. PMID:24075289

  15. 17β-Estradiol mediates superior adaptation of right ventricular function to acute strenuous exercise in female rats with severe pulmonary hypertension.

    PubMed

    Lahm, Tim; Frump, Andrea L; Albrecht, Marjorie E; Fisher, Amanda J; Cook, Todd G; Jones, Thomas J; Yakubov, Bakhtiyor; Whitson, Jordan; Fuchs, Robyn K; Liu, Aiping; Chesler, Naomi C; Brown, M Beth

    2016-08-01

    17β-Estradiol (E2) exerts protective effects on right ventricular (RV) function in pulmonary arterial hypertension (PAH). Since acute exercise-induced increases in afterload may lead to RV dysfunction in PAH, we sought to determine whether E2 allows for superior RV adaptation after an acute exercise challenge. We studied echocardiographic, hemodynamic, structural, and biochemical markers of RV function in male and female rats with sugen/hypoxia (SuHx)-induced pulmonary hypertension, as well as in ovariectomized (OVX) SuHx females, with or without concomitant E2 repletion (75 μg·kg(-1)·day(-1)) immediately after 45 min of treadmill running at 75% of individually determined maximal aerobic capacity (75% aerobic capacity reserve). Compared with males, intact female rats exhibited higher stroke volume and cardiac indexes, a strong trend for better RV compliance, and less pronounced increases in indexed total pulmonary resistance. OVX abrogated favorable RV adaptations, whereas E2 repletion after OVX markedly improved RV function. E2's effects on pulmonary vascular remodeling were complex and less robust than its RV effects. Postexercise hemodynamics in females with endogenous or exogenous E2 were similar to hemodynamics in nonexercised controls, whereas OVX rats exhibited more severely altered postexercise hemodynamics. E2 mediated inhibitory effects on RV fibrosis and attenuated increases in RV collagen I/III ratio. Proapoptotic signaling, endothelial nitric oxide synthase phosphorylation, and autophagic flux markers were affected by E2 depletion and/or repletion. Markers of impaired autophagic flux correlated with endpoints of RV structure and function. Endogenous and exogenous E2 exerts protective effects on RV function measured immediately after an acute exercise challenge. Harnessing E2's mechanisms may lead to novel RV-directed therapies. PMID:27288487

  16. Are Hemodynamics Surrogate Endpoints in Pulmonary Arterial Hypertension?

    PubMed Central

    Ventetuolo, Corey E.; Gabler, Nicole B.; Fritz, Jason S.; Smith, K. Akaya; Palevsky, Harold I.; Klinger, James R.; Halpern, Scott D.; Kawut, Steven M.

    2014-01-01

    Background While frequently assessed in trials and clinical practice, hemodynamic response to therapy has never been validated as a surrogate endpoint for clinical events in pulmonary arterial hypertension (PAH). Methods and Results We performed a patient-level pooled analysis of four randomized placebo-controlled trials to determine if treatment-induced changes in hemodynamic values at 12 weeks accounted for the relationship between treatment assignment and the probability of early clinical events (death, lung transplantation, atrial septostomy, PAH hospitalization, withdrawal for clinical worsening, escalation in PAH therapy). We included 1119 subjects with PAH. The median (interquartile range) age was 48 (37 – 59), and 23% were men. 656 (59%) received active therapy (101 [15%] iloprost, 118 [18%] sitaxsentan, 204 [31%] sildenafil, and 233 [36%] subcutaneous treprostinil). Active treatment significantly lowered right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), and pulmonary vascular resistance and increased cardiac output and index (p < 0.01 for all). Changes in hemodynamic values (except for RAP and mPAP) were significantly associated with the risk of a clinical event (p ≤ 0.01 for all). While active treatment approximately halved the odds of a clinical event compared to placebo (p < 0.001), changes in hemodynamics accounted for only 1.2 – 13.9% of the overall treatment effect. Conclusions Treatment-induced changes in hemodynamics at 12 weeks only partially explain the impact of therapy on the probability of early clinical events in PAH. These findings suggest that resting hemodynamics are not valid surrogate endpoints for short-term events in PAH clinical trials. PMID:24951771

  17. Physical Activity and Hemodynamic Reactivity in Chronic Kidney Disease

    PubMed Central

    Agarwal, Rajiv; Light, Robert P.

    2008-01-01

    Background and objectives: Patients with chronic kidney disease (CKD) have an elevated cardiovascular risk. This study was designed to understand better the presence and strength of the relationship between physical activity and BP and to explore determinants of hemodynamic reactivity. Design, setting, participants, & measurements: Twenty-four patients with CKD (mean age 69.5 yr; 3.1 antihypertensive drugs; estimated GFR 47 ml/min per 1.73 m2, albumin/creatinine ratio 403 mg/g) were studied on three occasions during a 6-wk period with 24-h ambulatory BP monitoring and simultaneous activity monitoring with wrist actigraphy. Results: Nondippers were found have a greater level of sleep activity compared with dippers, although the awake activity level was similar (7.06 versus 6.73) between groups (P = 0.042 for interaction). In 3587 BP activity pairs, hemodynamic reactivity was variable between individuals (systolic BP reactivity 1.06 [SD 10.50]; diastolic BP reactivity 0.89 [SD 7.80] heart rate reactivity 1.18 [SD 11.00]); those who were more sedentary had a greater increment in systolic BP compared with those who were less sedentary. Antihypertensive drugs blunted hemodynamic reactivity. Hemodynamic reactivity was greatest between 12 a.m. and 8 a.m., making this a vulnerable period for cardiovascular events. Conclusions: Greater hemodynamic reactivity in sedentary people with CKD offers a possible and thus far unrecognized mechanism of cardiovascular damage. Besides reducing BP, antihypertensive drugs reduce hemodynamic reactivity, which offers another plausible mechanism of cardiovascular protection with their use. PMID:18922983

  18. Reliability and reactivity of the prefrontal hemodynamic responses in essential hypertension: a functional near infrared spectroscopy study.

    PubMed

    Grant, Hercules; Bhambhani, Yagesh; Singhal, Anthony; Haennel, Robert; Warren, Sharon

    2015-10-01

    Prefrontal (PFC) cerebral vasoreactivity may be altered in hypertension but has not been studied during postural change and carbon dioxide (CO2) rebreathing. In this study, a dual procedure of 5% CO2 rebreathing with positional change (standing to supine and reverse) was performed on normotensive (N = 24) and essential hypertensive males (N = 16) (18-55 years) to assess reliability of PFC responses using functional near infrared spectroscopy. The groups (matched on age levels, N = 13) were also compared on their hemodynamic reactivity (change of oxyhemoglobin or total hemoglobin as a function of change in end tidal CO2). Test-retest reliability within one session and 7 days later was moderate to high (intraclass correlation coefficient = .63-.901) in both normotensive and hypertensive groups for all hemodynamic measures; whereas reliability of reactivity measures for oxyhemoglobin and total hemoglobin was moderate (intraclass correlation coefficient = .68-.762). Functional near infrared spectroscopy-measured PFC hemodynamic responses are highly reproducible in normotensive and adult essential hypertensive males. PMID:26329474

  19. Comprehensive cognitive and cerebral hemodynamic evaluation after cranioplasty

    PubMed Central

    Coelho, Fernanda; Oliveira, Arthur Maynart; Paiva, Wellingson Silva; Freire, Fabio Rios; Calado, Vanessa Tome; Amorim, Robson Luis; Neville, Iuri Santana; de Andrade, Almir Ferreira; Bor-Seng-Shu, Edson; Anghinah, Renato; Teixeira, Manoel Jacobsen

    2014-01-01

    Decompressive craniectomy is an established procedure to lower intracranial pressure and can save patients’ lives. However, this procedure is associated with delayed cognitive decline and cerebral hemodynamics complications. Studies show the benefits of cranioplasty beyond cosmetic aspects, including brain protection, and functional and cerebrovascular aspects, but a detailed description of the concrete changes following this procedure are lacking. In this paper, the authors report a patient with trephine syndrome who underwent cranioplasty; comprehensive cognitive and cerebral hemodynamic evaluations were performed prior to and following the cranioplasty. The discussion was based on a critical literature review. PMID:24833902

  20. Hemodynamic monitoring in the era of digital health.

    PubMed

    Michard, Frederic

    2016-12-01

    Digital innovations are changing medicine, and hemodynamic monitoring will not be an exception. Five to ten years from now, we can envision a world where clinicians will learn hemodynamics with simulators and serious games, will monitor patients with wearable or implantable sensors in the hospital and after discharge, will use medical devices able to communicate and integrate the historical, clinical, physiologic and biological information necessary to predict adverse events, propose the most rationale therapy and ensure it is delivered properly. Considerable intellectual and financial investments are currently made to ensure some of these new ideas and products soon become a reality. PMID:26885656

  1. Less invasive methods of advanced hemodynamic monitoring: principles, devices, and their role in the perioperative hemodynamic optimization

    PubMed Central

    2013-01-01

    The monitoring of the cardiac output (CO) and other hemodynamic parameters, traditionally performed with the thermodilution method via a pulmonary artery catheter (PAC), is now increasingly done with the aid of less invasive and much easier to use devices. When used within the context of a hemodynamic optimization protocol, they can positively influence the outcome in both surgical and non-surgical patient populations. While these monitoring tools have simplified the hemodynamic calculations, they are subject to limitations and can lead to erroneous results if not used properly. In this article we will review the commercially available minimally invasive CO monitoring devices, explore their technical characteristics and describe the limitations that should be taken into consideration when clinical decisions are made. PMID:24472443

  2. Focused review: spinal anesthesia in severe preeclampsia.

    PubMed

    Henke, Vanessa G; Bateman, Brian T; Leffert, Lisa R

    2013-09-01

    Spinal anesthesia is widely regarded as a reasonable anesthetic option for cesarean delivery in severe preeclampsia, provided there is no indwelling epidural catheter or contraindication to neuraxial anesthesia. Compared with healthy parturients, those with severe preeclampsia experience less frequent, less severe spinal-induced hypotension. In severe preeclampsia, spinal anesthesia may cause a higher incidence of hypotension than epidural anesthesia; however, this hypotension is typically easily treated and short lived and has not been linked to clinically significant differences in outcomes. In this review, we describe the advantages and limitations of spinal anesthesia in the setting of severe preeclampsia and the evidence guiding intraoperative hemodynamic management. PMID:23868886

  3. Ansys Fluent versus Sim Vascular for 4-D patient-specific computational hemodynamics in renal arteries

    NASA Astrophysics Data System (ADS)

    Mumbaraddi, Avinash; Yu, Huidan (Whitney); Sawchuk, Alan; Dalsing, Michael

    2015-11-01

    The objective of this clinical-need driven research is to investigate the effect of renal artery stenosis (RAS) on the blood flow and wall shear stress in renal arteries through 4-D patient-specific computational hemodynamics (PSCH) and search for possible critical RASs that significantly alter the pressure gradient across the stenosis by manually varying the size of RAS from 50% to 95%. The identification of the critical RAS is important to understand the contribution of RAS to the overall renal resistance thus appropriate clinical therapy can be determined in order to reduce the hypertension. Clinical CT angiographic data together with Doppler Ultra sound images of an anonymous patient are used serving as the required inputs of the PSCH. To validate the PSCH, we use both Ansys Fluent and Sim Vascular and compare velocity, pressure, and wall-shear stress under identical conditions. Renal Imaging Technology Development Program (RITDP) Grant.

  4. The Acute Effect of Resistance Exercise with Blood Flow Restriction with Hemodynamic Variables on Hypertensive Subjects

    PubMed Central

    Araújo, Joamira P.; Silva, Eliney D.; Silva, Julio C. G.; Souza, Thiago S. P.; Lima, Eloíse O.; Guerra, Ialuska; Sousa, Maria S. C.

    2014-01-01

    The purpose of this study was to analyze systolic blood pressure (SBP), diastolic blood pressure (DBP) and the heart rate (HR) before, during and after training at moderate intensity (MI, 50%-1RM) and at low intensity with blood flow restriction (LIBFR). In a randomized controlled trial study, 14 subjects (average age 45±9,9 years) performed one of the exercise protocols during two separate visits to the laboratory. SBP, DBP and HR measurements were collected prior to the start of the set and 15, 30, 45 and 60 minutes after knee extension exercises. Repeated measures of analysis of variance (ANOVA) were used to identify significant variables (2 × 5; group × time). The results demonstrated a significant reduction in SBP in the LIBFR group. These results provide evidence that strength training performed acutely alters hemodynamic variables. However, training with blood flow restriction is more efficient in reducing blood pressure in hypertensive individuals than training with moderate intensity. PMID:25713647

  5. Hemodynamic Changes Following Endotracheal Intubation With Glidescope® Video-Laryngoscope in Patients With Untreated Hypertension

    PubMed Central

    Dashti, Majid; Amini, Shahram; Azarfarin, Rasoul; Totonchi, Ziae; Hatami, Maryam

    2014-01-01

    Background: Tracheal intubation can be associated with considerable hemodynamic changes, particularly in patients with uncontrolled hypertension. The GlideScope® video-laryngoscope (GVL) is a novel video laryngoscope that does not need direct exposure of the vocal cords, and it can also produce lower hemodynamic changes due to lower degrees of trauma and stimuli to the oropharynx than a Macintosh direct laryngoscope (MDL). Objectives: The aim of this clinical trial was to compare hemodynamic alterations following tracheal intubation with a GVL and MDL in patients with uncontrolled hypertension. Patients and Methods: Sixty patients who had uncontrolled hypertension and scheduled for elective surgery requiring tracheal intubation, were randomly assigned to receive intubated with either a GVL (n = 30) or a MDL (n = 30). Intubation time, heart rate, rate pressure product (RPP), and mean arterial blood pressure (MAP), were compared between the two groups at; baseline, following induction of anesthesia, after intubation, and at one minute intervals for 5 minutes. Results: A total of 59 patients finished the study. Intubation time was longer in the GVL group (9.80 ± 1.27 s) than in the MDL group (8.20 ± 1.17 s) (P < 0.05). MAP, pulse rate, and RPP were lower in the GVL than the MDL group after endotracheal intubation (P < 0.05). MAP, heart rate, and RPP returned to pre-intubation values at 3 and 4 minutes after intubation in the GVL and MDL groups, respectively (P < 0.05). Conclusions: Hemodynamic fluctuations in patients with uncontrolled hypertension after endotracheal intubation were lower with the GVL than the MDL technique. PMID:25478537

  6. Effects of ranolazine on exercise capacity, right ventricular indices, and hemodynamic characteristics in pulmonary arterial hypertension: a pilot study

    PubMed Central

    Khan, Sadiya S.; Cuttica, Michael J.; Beussink-Nelson, Lauren; Kozyleva, Anastasia; Sanchez, Cynthia; Mkrdichian, Hamorabi; Selvaraj, Senthil; Dematte, Jane E.; Lee, Daniel C.

    2015-01-01

    Abstract Ranolazine, a late inward sodium current and fatty acid oxidation inhibitor, may improve right ventricular (RV) function in pulmonary arterial hypertension (PAH); however, the safety and efficacy of ranolazine in humans with PAH is unknown. Therefore, we sought to (1) determine whether ranolazine is safe and well tolerated in PAH and (2) explore ranolazine’s effect on symptoms, exercise capacity, RV structure and function, and hemodynamic characteristics. We therefore conducted a 3-month, prospective, open-label pilot study involving patients with symptomatic PAH (n = 11) and echocardiographic evidence of RV dysfunction. We evaluated the safety and tolerability of ranolazine and compared symptoms, exercise capacity, exercise bicycle echocardiographic parameters, and invasive hemodynamic parameters between baseline and 3 months of ranolazine therapy using paired t tests. Of the 11 patients enrolled, one discontinued ranolazine therapy due to a drug-drug interaction after 3 days of therapy. All 10 of the remaining patients continued therapy for 3 months, and 8 (80%) of 10 completed all study tests. After 3 months, ranolazine administration was safe and associated with improvement in functional class (P = 0.0013), reduction in RV size (P = 0.015), improved RV function (improvement in RV strain during exercise at 3 months; P = 0.037), and a trend toward improved exercise time and exercise watts on bicycle echocardiography (P = 0.06 and 0.01, respectively). Ranolazine was not associated with improvement in invasive hemodynamic parameters. In conclusion, in a pilot study involving PAH, ranolazine therapy was safe and well tolerated, and it resulted in improvement in symptoms and echocardiographic parameters of RV structure and function but did not alter invasive hemodynamic parameters. ClinicalTrials.gov Identifier: NCT01174173. PMID:26401256

  7. Effects of ranolazine on exercise capacity, right ventricular indices, and hemodynamic characteristics in pulmonary arterial hypertension: a pilot study.

    PubMed

    Khan, Sadiya S; Cuttica, Michael J; Beussink-Nelson, Lauren; Kozyleva, Anastasia; Sanchez, Cynthia; Mkrdichian, Hamorabi; Selvaraj, Senthil; Dematte, Jane E; Lee, Daniel C; Shah, Sanjiv J

    2015-09-01

    Ranolazine, a late inward sodium current and fatty acid oxidation inhibitor, may improve right ventricular (RV) function in pulmonary arterial hypertension (PAH); however, the safety and efficacy of ranolazine in humans with PAH is unknown. Therefore, we sought to (1) determine whether ranolazine is safe and well tolerated in PAH and (2) explore ranolazine's effect on symptoms, exercise capacity, RV structure and function, and hemodynamic characteristics. We therefore conducted a 3-month, prospective, open-label pilot study involving patients with symptomatic PAH (n = 11) and echocardiographic evidence of RV dysfunction. We evaluated the safety and tolerability of ranolazine and compared symptoms, exercise capacity, exercise bicycle echocardiographic parameters, and invasive hemodynamic parameters between baseline and 3 months of ranolazine therapy using paired t tests. Of the 11 patients enrolled, one discontinued ranolazine therapy due to a drug-drug interaction after 3 days of therapy. All 10 of the remaining patients continued therapy for 3 months, and 8 (80%) of 10 completed all study tests. After 3 months, ranolazine administration was safe and associated with improvement in functional class (P = 0.0013), reduction in RV size (P = 0.015), improved RV function (improvement in RV strain during exercise at 3 months; P = 0.037), and a trend toward improved exercise time and exercise watts on bicycle echocardiography (P = 0.06 and 0.01, respectively). Ranolazine was not associated with improvement in invasive hemodynamic parameters. In conclusion, in a pilot study involving PAH, ranolazine therapy was safe and well tolerated, and it resulted in improvement in symptoms and echocardiographic parameters of RV structure and function but did not alter invasive hemodynamic parameters. ClinicalTrials.gov Identifier: NCT01174173. PMID:26401256

  8. Interleaved imaging of cerebral hemodynamics and blood flow index to monitor ischemic stroke and treatment in rat by volumetric diffuse optical tomography.

    PubMed

    Lin, Zi-Jing; Ren, Ming; Li, Lin; Liu, Yueming; Su, Jianzhong; Yang, Shao-Hua; Liu, Hanli

    2014-01-15

    Diffuse optical tomography (DOT) has been used by several groups to assess cerebral hemodynamics of cerebral ischemia in humans and animals. In this study, we combined DOT with an indocyanine green (ICG)-tracking method to achieve interleaved images of cerebral hemodynamics and blood flow index (BFI) using two middle cerebral artery occlusion (MCAO) rat models. To achieve volumetric images with high-spatial resolution, we first integrated a depth compensation algorithm (DCA) with a volumetric mesh-based rat head model to generate three-dimensional (3D) DOT on a rat brain atlas. Then, the experimental DOT data from two rat models were collected using interleaved strategy for cerebral hemodynamics and BFI during and after ischemic stroke, with and without a thrombolytic therapy for the embolic MCAO model. The acquired animal data were further analyzed using the integrated rat-atlas-guided DOT method to form time-evolving 3D images of both cerebral hemodynamics and BFI. In particular, we were able to show and identify therapeutic outcomes of a thrombolytic treatment applied to the embolism-induced ischemic model. This paper demonstrates that volumetric DOT is capable of providing high-quality, interleaved images of cerebral hemodynamics and blood perfusion in small animals during and after ischemic stroke, with excellent 3D visualization and quantifications. PMID:23872158

  9. Interleaved imaging of cerebral hemodynamics and blood flow index to monitor ischemic stroke and treatment in rat by volumetric diffuse optical tomography

    PubMed Central

    Lin, Zi-Jing; Ren, Ming; Li, Lin; Liu, Yueming; Su, Jianzhong; Yang, Shao-Hua; Liu, Hanli

    2013-01-01

    Diffuse optical tomography (DOT) has been used by several groups to assess cerebral hemodynamics of cerebral ischemia in humans and animals. In this study, we combined DOT with an indocyanine green (ICG)-tracking method to achieve interleaved images of cerebral hemodynamics and blood flow index (BFI) using two middle cerebral artery occlusion (MCAO) rat models. To achieve volumetric images with high-spatial resolution, we first integrated a depth compensation algorithm (DCA) with a volumetric mesh-based rat head model to generate three-dimensional (3D) DOT on a rat brain atlas. Then, the experimental DOT data from two rat models were collected using interleaved strategy for cerebral hemodynamics and BFI during and after ischemic stroke, with and without a thrombolytic therapy for the embolic MCAO model. The acquired animal data were further analyzed using the integrated rat-atlas-guided DOT method to form time-evolving 3D images of both cerebral hemodynamics and BFI. In particular, we were able to show and identify therapeutic outcomes of a thrombolytic treatment applied to the embolism-induced ischemic model. This paper demonstrates that volumetric DOT is capable of providing high-quality, interleaved images of cerebral hemodynamics and blood perfusion in small animals during and after ischemic stroke, with excellent 3D visualization and quantifications. PMID:23872158

  10. Quantitative assessment of hemodynamic changes during spinal dural arteriovenous fistula surgery.

    PubMed

    Shi, Wei; Qiao, Guangyu; Sun, Zhenghui; Shang, Aijia; Wu, Chen; Xu, Bainan

    2015-07-01

    We aimed to evaluate the efficacy of FLOW 800 (Carl Zeiss Meditec, Jena, Thuringia, Germany) with indocyanine green (ICG) videoangiography for the quantitative assessment of flow dynamics in spinal dural arteriovenous fistula (dAVF) surgeries. We prospectively enrolled nine patients with spinal dAVF diagnosed within the past year and performed FLOW 800 analyses using ICG videoangiography before and after surgical obliteration of the fistula. A color-coded map was semi-automatically generated by FLOW 800 and used for high-resolution visualization of the vasculature and instant interpretation of the dynamic flow changes. The FLOW 800-specific hemodynamic parameters were employed for real-time measurements of parenchymal perfusion alterations. Overall, 18 intraoperative FLOW 800 analyses using ICG videoangiography were performed in nine patients. The color-coded map aided the detection and complete obliteration of the fistulas in all patients and the results were verified by postoperative spinal digital subtraction angiography. The transit time parameter was significantly shorter in the preobliteration phase than in the postobliteration phase (p < 0.01), the rise time parameter exhibited the same pattern (p = 0.08) and maximum intensity and blood flow index were not significantly different between these phases. FLOW 800 with ICG videoangiography provided an intuitive and objective understanding of blood flow dynamics intraoperatively and enabled easy and confident identification and treatment of this pathology. The FLOW 800-specific hemodynamic analyses provided additional perfusion information that enabled real-time measurements of parenchymal perfusion alterations. FLOW 800 with ICG videoangiography is useful for intraoperative quantitative assessment of flow dynamics, facilitating safety and confidence in the treatment of spinal dAVF. PMID:25934113

  11. [Introduction of Hemodynamic Monitoring in Critical Care Units].

    PubMed

    Lin, Chen-Wei; Wang, Shiao-Pei

    2016-02-01

    Hemodynamic monitoring is a very important treatment in intensive care units. Measurements taken during monitoring include pulmonary artery catheter (PAC), pulse-induced contour output (PiCCO), and non-invasive hemodynamic monitoring. PAC measures cardiopulmonary parameters using the thermodilution principle. PiCCO uses transpulmonary thermodilution and pulse contour analysis to measure cardiopulmonary parameters and extra-vascular lung water, to predict lung edema, and to differentiate between cardiogenic and non-cardiogenic respiratory failure. Non-invasive hemodynamic monitoring uses the thoracic electrical bioimpedance principle to measure electrical conductivity and then calculates stroke volume and cardiopulmonary parameters using the arrangement of red blood cells. The author is a nurse in an intensive care unit who is familiar with the various methods used in hemodynamic monitoring, with preparing the related devices, with briefing patients and family members prior to procedures, with related aseptic skills, with preventing complications during the insertion procedure, and with analyzing and interpreting those parameters accurately. The issues addressed in this paper are provided as a reference for nurses and other medical personnel to choose appropriate treatments when caring for critical patients. PMID:26813070

  12. [Mathematical model of baroreflex regulation of hemodynamics in the dog].

    PubMed

    Palets, B L

    1983-11-01

    A non-linear mathematical model of dog hemodynamics regulation was developed including descriptions of the cardiovascular system, the arterial baroreflex and the Beinbridge reflex. Model calculated arterial and venous pressure, blood flow, and heart rate are in good agreement with experimental data. PMID:6653829

  13. Central circulatory hemodynamics as a function of gravitational stress

    NASA Technical Reports Server (NTRS)

    Latham, Rick D.; White, C. D.; Fanton, J. W.; Owens, R. W.; Barber, J. F.; Lewkowski, B. E.; Goff, O. T.

    1991-01-01

    This study focuses on an evaluation of the central hemodynamics in a nonhuman primate model to variations in gravitational states. The baboon, phylogenectically close to man, was chosen as the human surrogate. The study environments selected are head-down and head-up tilt in the physiology laboratory, centrifugation to test hypergravic stress, and parabolic flights to test transient acute responses to microgravity.

  14. Segmental hemodynamics during partial liquid ventilation in isolated rat lungs

    PubMed Central

    Ko, Angela C.; Hirsh, Emily; Wong, Andrew C.; Moore, Timothy M.; Taylor, Aubrey E.; Hirschl, Ronald B.; Younger, John G.

    2011-01-01

    Partial liquid ventilation (PLV) is a means of ventilatory support in which gas ventilation is carried out in a lung partially filled with a perfluorocarbon liquid capable of supporting gas exchange. Recently, this technique has been proposed as an adjunctive therapy for cardiac arrest, during which PLV with cold perfluorocarbons might rapidly cool the intrathoracic contents and promote cerebral protective hypothermia while not interfering with gas exchange. A concern during such therapy will be the effect of PLV on pulmonary hemodynamics during very low blood flow conditions. In the current study, segmental (i.e. precapillary, capillary, and postcapillary) hemodynamics were studied in the rat lung using a standard isolated lung perfusion system at a flow rate of 6 ml/min ( ~5% normal cardiac output). Lungs received either gas ventilation or 5 or 10 ml/kg PLV. Segmental pressures and vascular resistances were determined, as was transcapillary fluid flux. The relationship between individual hemodynamic parameters and PLV dose was examined using linear regression, with n = 5 in each study group. PLV at both the 5 and 10 ml/kg dose produced no detectable changes in pulmonary blood flow or in transcapillary fluid flux (all R2 values < 0.20). Conclusion: In an isolated perfused lung model of low flow conditions, normal segmental hemodynamic behavior was preserved during liquid ventilation. These data support further investigation of this technique as an adjunct to cardiopulmonary resuscitation. PMID:12668304

  15. Numerical analysis of hemodynamics in spastic middle cerebral arteries.

    PubMed

    Wen, Jun; Wang, Qingfeng; Wang, Qingyuan; Khoshmanesh, Khashayar; Zheng, Tinghui

    2016-11-01

    Cerebral vasospasm (CVS) is the most common serious complication of subarachnoid hemorrhage. Among the many factors that are associated with the pathogenesis of CVS, hemodynamics plays an important role in the initiation and development of CVS. Numerical simulation was carried out to obtain the flow patterns and wall shear stress (WSS) distribution in spastic middle cerebral arteries. The blood was assumed to be incompressible, laminar, homogenous, Newtonian, and steady. Our simulations reveal that flow velocity and WSS level increase at the stenosis segment of the spastic vessels, but further downstream of stenosis, the WSS significantly decreases along the inner wall, and flow circulation and stagnation are observed. The hydrodynamic resistance increases with the increase of vessel spasm. Moreover, the change of flow field and hydrodynamic forces are not linearly proportional to the spasm level, and the rapid change of hemodynamic parameters is observed as the spasm is more than 50%. Accordingly, in the view of hemodynamic physiology, vessels with less than 30% stenosis are capable of self-restoration towards normal conditions. However, vessels with more than 50% stenosis may eventually lose their capacity to adapt to differing physiologic conditions due to the extreme non-physilogic hemodynamic environment, and the immediate expansion of the vessel lumen might be needed to minimize serious and non-reversible effects. PMID:26942314

  16. Elementary Hemodynamic Principles Based on Modified Bernoulli's Equation.

    ERIC Educational Resources Information Center

    Badeer, Henry S.

    1985-01-01

    Develops and expands basic concepts of Bernoulli's equation as it applies to vascular hemodynamics. Simple models are used to illustrate gravitational potential energy, steady nonturbulent flow, pump-driven streamline flow, and other areas. Relationships to the circulatory system are also discussed. (DH)

  17. Fluid-Structure Interaction Modeling of Intracranial Aneurysm Hemodynamics: Effects of Different Assumptions

    NASA Astrophysics Data System (ADS)

    Rajabzadeh Oghaz, Hamidreza; Damiano, Robert; Meng, Hui

    2015-11-01

    Intracranial aneurysms (IAs) are pathological outpouchings of cerebral vessels, the progression of which are mediated by complex interactions between the blood flow and vasculature. Image-based computational fluid dynamics (CFD) has been used for decades to investigate IA hemodynamics. However, the commonly adopted simplifying assumptions in CFD (e.g. rigid wall) compromise the simulation accuracy and mask the complex physics involved in IA progression and eventual rupture. Several groups have considered the wall compliance by using fluid-structure interaction (FSI) modeling. However, FSI simulation is highly sensitive to numerical assumptions (e.g. linear-elastic wall material, Newtonian fluid, initial vessel configuration, and constant pressure outlet), the effects of which are poorly understood. In this study, a comprehensive investigation of the sensitivity of FSI simulations in patient-specific IAs is investigated using a multi-stage approach with a varying level of complexity. We start with simulations incorporating several common simplifications: rigid wall, Newtonian fluid, and constant pressure at the outlets, and then we stepwise remove these simplifications until the most comprehensive FSI simulations. Hemodynamic parameters such as wall shear stress and oscillatory shear index are assessed and compared at each stage to better understand the sensitivity of in FSI simulations for IA to model assumptions. Supported by the National Institutes of Health (1R01 NS 091075-01).

  18. Association between hemodynamic presentation and outcome in sepsis patients.

    PubMed

    Hwang, Sung Yeon; Shin, Tae Gun; Jo, Ik Joon; Jeon, Kyeongman; Suh, Gee Young; Lee, Tae Rim; Cha, Won Chul; Sim, Min Seob; Song, Keun Jeong; Jeong, Yeon Kwon

    2014-09-01

    We aimed to compare outcomes of sepsis patients according to their hemodynamic presentation: cryptic shock (CS), cryptic to overt shock (COS), and overt shock (OS). We analyzed the sepsis registry for adult patients who presented to the emergency department (ED) of a tertiary hospital and met the criteria for severe sepsis or septic shock between August 2008 and March 2012. We classified the patients as having CS, COS, or OS. "Cryptic shock" was defined as severe sepsis with a lactate level of 4 mmol/L or greater and normotension, "COS" was defined as initial CS that progressed to septic shock within 72 h, and "OS" was defined as septic shock on ED arrival. The primary outcome was in-hospital mortality. We performed a multivariable logistic regression analysis to assess variables related to in-hospital mortality and a multivariable Cox regression analysis to assess predictive factors for progression to OS in patients who initially showed CS. A total of 591 patients were included. We assigned 187 (31.6%) patients to the CS group, 157 (26.6%) patients to the COS group, and 247 (41.8%) patients to the OS group. There was a significant difference in unadjusted in-hospital mortality among groups (7.0% in the CS group, 27.4% in the COS group, and 21.9% in the OS group; P < 0.01). Multivariable analysis showed an odds ratio (OR) for in-hospital mortality of 0.17 (95% confidence interval, 0.07 - 0.40; P < 0.01) for the CS group and 0.83 (95% confidence interval, 0.46 - 1.49; P = 0.54) for the COS group compared with the OS group. A higher blood lactate concentration and respiratory failure were significant risk factors for progression to OS. In conclusion, CS without deterioration to hypotension during initial treatment showed significantly lower mortality than OS. The mortality from CS that progressed to apparent hypotension, however, was comparable to the mortality associated with OS. PMID:24978884

  19. Severe refractory hypertension during shoulder arthroscopy

    PubMed Central

    Abrons, RO; Ellis, SE

    2016-01-01

    The use of epinephrine-containing saline irrigating solutions during arthroscopic shoulder surgery gained popularity after it was reported that the addition of epinephrine reduced bleeding and improved visualization without adverse cardiovascular effects. We share a case of a patient undergoing shoulder arthroscopy who received a standard intra-articular infusion of epinephrine-containing normal saline (1 mcg/mL) and experienced severe hemodynamic consequences. PMID:27051380

  20. [Effects of phenibut on parameters of cerebral hemodynamics in swimmers with dysadaptation syndrome and various types of systemic hemodynamics].

    PubMed

    Likhodeeva, V A; Spasov, A A; Isupov, I B; Mandrikov, V B

    2010-08-01

    Administration of phenibut (0.25 g) during 4 weeks as a means of rehabilitation promoted optimization of the biochemical status and cerebral blood circulation in swimmers with various types of systemic hemodynamics, which were examined 20 minutes after warm-up. PMID:20919550

  1. Study Design of the Microcirculatory Shock Occurrence in Acutely Ill Patients (microSOAP): an International Multicenter Observational Study of Sublingual Microcirculatory Alterations in Intensive Care Patients

    PubMed Central

    Vellinga, Namkje A. R.; Boerma, E. Christiaan; Koopmans, Matty; Donati, Abele; Dubin, Arnaldo; Shapiro, Nathan I.; Pearse, Rupert M.; Bakker, Jan; Ince, Can

    2012-01-01

    Objective. Sublingual microcirculatory alterations are associated with an adverse prognosis in several critical illness subgroups. Up to now, single-center studies have reported on sublingual microcirculatory alterations in ICU patient subgroups, but an extensive evaluation of the prevalence of these alterations is lacking. We present the study design of an international multicenter observational study to investigate the prevalence of microcirculatory alterations in critically ill: the Microcirculatory Shock Occurrence in Acutely ill Patients (microSOAP). Methods. 36 ICU's worldwide have participated in this study aiming for inclusion of over 500 evaluable patients. To enable communication and data collection, a website, an Open Clinica 3.0 database, and image uploading software have been designed. A one-session assessment of the sublingual microcirculation using Sidestream Dark Field imaging and data collection on patient characteristics has been performed in every ICU patient >18 years, regardless of underlying disease. Statistical analysis will provide insight in the prevalence and severity of sublingual alterations, its relation to systemic hemodynamic variables, disease, therapy, and outcome. Conclusion. This study will be the largest microcirculation study ever performed. It is expected that this study will also establish a basis for future studies related to the microcirculation in critically ill. PMID:22666566

  2. Evidence for Cerebral Hemodynamic Measurement-based Therapy in Symptomatic Major Cerebral Artery Disease

    PubMed Central

    YAMAUCHI, Hiroshi

    In patients with atherosclerotic internal carotid artery or middle cerebral artery occlusive disease, chronic reduction in cerebral perfusion pressure (chronic hemodynamic compromise) increases the risk of ischemic stroke and can be detected by directly measuring hemodynamic parameters. However, strategies for selecting treatments based on hemodynamic measurements have not been clearly established. Bypass surgery has been proven to improve hemodynamic compromise. However, the benefit of bypass surgery for reducing the stroke risk in patients with hemodynamic compromise is controversial. The results of the two randomized controlled trials were inconsistent. Hypertension is a major risk factor for stroke, and antihypertensive therapy provides general benefit to patients with symptomatic atherosclerotic major cerebral artery disease. However, the benefit of strict control of blood pressure for reducing the stroke risk in patients with hemodynamic compromise is a matter of debate. The results of the two observational studies were different. We must establish strategies for selecting treatments based on hemodynamic measurements in atherosclerotic major cerebral artery disease. PMID:26041631

  3. Chronic tempol treatment attenuates the renal hemodynamic effects induced by a heme oxygenase inhibitor in streptozotocin diabetic rats.

    PubMed

    Rodriguez, Francisca; Lopez, Bernardo; Perez, Cayetano; Fenoy, Francisco J; Hernandez, Isabel; Stec, David E; Li Volti, Giovanni; Salom, Miguel G

    2011-11-01

    Heme oxygenase-1 (HO-1) is induced by oxidative stress and plays an important role in protecting the kidney from oxidant-mediated damage in the streptozotocin (STZ) rat model of type-1 diabetes mellitus (DM-1). HO-derived metabolites, presumably carbon monoxide (CO), mediate vasodilatory influences in the renal circulation, particularly in conditions linked to elevated HO-1 protein expression or diminished nitric oxide (NO) levels. We tested the hypothesis that diabetes increases oxidative stress and induces HO-1 protein expression, which contributes to regulate renal hemodynamics in conditions of low NO bioavailability. Two weeks after the induction of diabetes with STZ (65 mg/kg iv), Sprague-Dawley rats exhibited higher renal HO-1 protein expression, hyperglycemia, and elevated renal nitrotyrosine levels than control normoglycemic animals. In anesthetized diabetic rats, renal vascular resistance (RVR) was increased, and in vivo cortical NO levels were reduced (P < 0.05) compared with control animals. Acute administration of the HO inhibitor Stannous mesoporphyrin (SnMP; 40 μmol/kg iv) did not alter renal hemodynamics in control rats, but greatly decreased glomerular filtration rate and renal blood flow, markedly increasing RVR in hyperglycemic diabetic rats. Chronic oral treatment with the SOD mimetic tempol prevented the elevation of nitrotyrosine, the HO-1 protein induction, and the increases in RVR induced by SnMP in the diabetic group, without altering basal NO concentrations or RVR. Increasing concentrations of a CO donor (CO-releasing molecule-A1) on pressurized renal interlobar arteries elicited a comparable relaxation in vessels taken from control or diabetic animals. These results suggest that oxidative stress-induced HO-1 exerts vasodilatory actions that partially maintain renal hemodynamics in uncontrolled DM-1. PMID:21849637

  4. DNA ALTERATIONS

    EPA Science Inventory

    The exposure of an organism to genotoxic chemicals may induce a cascade of genetic events. nitially, structural alterations to DNA are formed. ext, the DNA damage is processed and subsequently expressed in mutant gene products. inally, diseases result from the genetic damage. he ...

  5. Hemodynamics are altered in the caudal artery of beef heifers fed different ergot alkaloid concentrations.

    PubMed

    Aiken, G E; Strickland, J R; Looper, M L; Bush, L P; Schrick, F N

    2009-06-01

    Doppler ultrasonography was used to compare blood flow characteristics in the caudal artery of heifers fed diets with endophyte (Neotyphodium coenophialum) noninfected (E-, 0 microg of ergovaline/g of DM), a 1:1 mixture of endophyte-infected and E- (E+E-; 0.39 microg of ergovaline/g of DM), or endophyte-infected (E+, 0.79 microg of ergovaline/g of DM) tall fescue (Lolium arundinaceum) seed. Eighteen crossbred (Angus x Brangus) heifers [345 +/- 19 kg (SD)] were assigned to individual pens and fed chopped alfalfa hay plus a concentrate that contained E- tall fescue seed for 7 d during an adjustment period. A 9-d experimental period followed with feeding treatments of chopped alfalfa hay plus a concentrate with E+, E-, or E+E- seed being assigned randomly to pens. Doppler ultrasound measurements (caudal artery luminal area, peak systolic velocity, end diastolic velocity, mean velocity, heart rate, and flow rate) and serum prolactin were monitored during the adjustment (3 baseline measures) and during the experimental period (7 measures). Statistical analyses compared proportionate differences between baseline and responses at 3, 27, 51, 75, 171, and 195 h from initial feeding of the experimental diets. Serum prolactin concentrations for E+ and E+E- diets were less (P < 0.001) than baseline concentrations beginning at 27 and 51 h, respectively, from initial feeding of the diets. Although baseline measures were taken when ambient temperatures were likely below thermoneutrality, caudal artery luminal cross-sectional area in E+ heifers had declined (P = 0.004) from baseline by 27 h and remained less (P < 0.02) until 195 h, and caudal artery luminal area declined (P = 0.004) in E+E- heifers from baseline by 51 h and remained less (P < 0.07) until 171 h. Blood flow rate was slower than the baseline rate at 51 h for E+ (P = 0.058) and E+E- (P = 0.02 heifers, but blood flow remained slower in E+E- heifers for 48 h, whereas it remained slower in E+ heifers for 96 h. Adjustments in artery luminal area and blood rate with the 3 diets appeared to parallel the increases in ambient temperature. Heifers fed a diet containing a larger amount of ergot alkaloids had less of a response to ambient temperature than heifers consuming the diet with less or no ergot alkaloids. PMID:19251925

  6. Hemodynamics are Altered in the Caudal Artery of Beef Heifers Fed Different Ergot Alkaloid Concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tall fescue is a cool-season perennial grass that is widely utilized for grazing in a region covering the transition zone between the temperate northeast and the subtropical southeast Although tall fescue is well adapted to the climate and soils in the region, an endophytic fungus infects fescue pla...

  7. Preventive role of exercise training in autonomic, hemodynamic, and metabolic parameters in rats under high risk of metabolic syndrome development.

    PubMed

    Moraes-Silva, Ivana Cinthya; Mostarda, Cristiano; Moreira, Edson Dias; Silva, Kleiton Augusto Santos; dos Santos, Fernando; de Angelis, Kátia; Farah, Vera de Moura Azevedo; Irigoyen, Maria Claudia

    2013-03-15

    High fructose consumption contributes to metabolic syndrome incidence, whereas exercise training promotes several beneficial adaptations. In this study, we demonstrated the preventive role of exercise training in the metabolic syndrome derangements in a rat model. Wistar rats receiving fructose overload in drinking water (100 g/l) were concomitantly trained on a treadmill (FT) or kept sedentary (F) for 10 wk. Control rats treated with normal water were also submitted to exercise training (CT) or sedentarism (C). Metabolic evaluations consisted of the Lee index and glycemia and insulin tolerance test (kITT). Blood pressure (BP) was directly measured, whereas heart rate (HR) and BP variabilities were evaluated in time and frequency domains. Renal sympathetic nerve activity was also recorded. F rats presented significant alterations compared with all the other groups in insulin resistance (in mg · dl(-1) · min(-1): F: 3.4 ± 0.2; C: 4.7 ± 0.2; CT: 5.0 ± 0.5 FT: 4.6 ± 0.4), mean BP (in mmHG: F: 117 ± 2; C: 100 ± 2; CT: 98 ± 2; FT: 105 ± 2), and Lee index (in g/mm: F = 0.31 ± 0.001; C = 0.29 ± 0.001; CT = 0.27 ± 0.002; FT = 0.28 ± 0.002), confirming the metabolic syndrome diagnosis. Exercise training blunted all these derangements. Additionally, FS group presented autonomic dysfunction in relation to the others, as seen by an ≈ 50% decrease in baroreflex sensitivity and 24% in HR variability, and increases in sympathovagal balance (140%) and in renal sympathetic nerve activity (45%). These impairments were not observed in FT group, as well as in C and CT. Correlation analysis showed that both Lee index and kITT were associated with vagal impairment caused by fructose. Therefore, exercise training plays a preventive role in both autonomic and hemodynamic alterations related to the excessive fructose consumption. PMID:23329818

  8. C5a-induced hemodynamic and hematologic changes in the rabbit. Role of cyclooxygenase products and polymorphonuclear leukocytes.

    PubMed Central

    Lundberg, C.; Marceau, F.; Hugli, T. E.

    1987-01-01

    Hemodynamic and hematologic changes occurring after intravascular complement activation have implicated the anaphylatoxins in this response. In this study, the hemodynamic and hematologic effects of purified C5a were investigated in rabbits; and involvement of prostanoids, histamine, and polymorphonuclear leukocytes (PMNs) were examined. The anaphylatoxin C5a induces a reversible systemic arterial hypotension which coincides with an increase in central venous pressure (CVP), decreased cardiac output (CO), increased plasma prostanoid levels, as well as neutropenia. Total peripheral resistance (TPR) remained unchanged. The cyclooxygenase inhibitor indomethacin abolished the C5a-induced hypotension and normalized plasma prostanoid levels without altering the C5a-induced neutropenia. The thromboxane (Tx) A2 synthetase inhibitor dazoxiben reduced TxB2 plasma levels and increased 6-keto-prostaglandin PGF1 alpha and PGE2 levels without altering the hypotensive response. However, with dazoxiben treatment both TPR and CVP decreased. The H2-receptor antagonist cimetidine reduced C5a-induced hypotension and diminished prostanoid release. Both the hypotensive response and elevated prostanoid release were observed after C5a challenge in animals rendered neutropenic prior to challenge. It is concluded that C5a-induced arterial hypotension in the rabbit is a PMN-independent reaction, mediated through cyclooxygenase products and, to some degree, by histamine. The mechanism producing systemic arterial hypotension does not seem to involve peripheral vasodilation but appears to be a secondary effect of pulmonary vasoconstriction, possibly mediated by TxA2. PMID:3115110

  9. Efficacy of the valsalva maneuver on needle projection pain and hemodynamic responses during spinal puncture.

    PubMed

    Mohammadi, Sussan Soltani; Pajand, Amin Ghasemi; Shoeibi, Gita

    2011-01-01

    This study evaluated the efficacy of the valsalva maneuver that can induce baroreceptor activation and nociception, on needle projection pain and hemodynamic responses associated with spinal puncture. Ninety adults, ASA physical status I and II undergoing elective surgeries were included. Patients were randomized into three equal groups. Group I (C): control; Group II (B): ball; pressed a rubber ball (attention-diverting method); Group III (V): valsalva; blew into sphygmomanometer tubing and hold the mercury column up to 30 mm Hg for a period of at least 20s. Spinal needle projection pain was graded using numeric rating scale (NRS): 1-10, where scales of 1-3 were rated as mild, 4-6 as moderate, and >6 as severe. Blood pressure and heart rate, five minutes before the procedure, during the spinal puncture and first and third minutes after that, were also recorded. Significant reduction in NRS was observed in the valsalva group compared with the control and the ball groups (p=0.001). There were statistical but no significant clinical differences in mean arterial blood pressure and heart rates between the study groups (P=0.008 and P=0.016 respectively). In conclusion valsalva maneuver can decrease the skin puncture pain associated with spinal needle projection while observing hemodynamic changes. PMID:21369370

  10. Prefrontal Hemodynamic Functions during a Verbal Fluency Task in Blepharospasm Using Multi-Channel NIRS.

    PubMed

    Shen, Chen-Yu; Wang, Yong-Jun; Zhang, Xiao-Qian; Liu, Xiao-Min; Ren, Xia-Jin; Ma, Xiang-Yun; Sun, Jing-Jing; Feng, Kun; Sun, Gao-Xiang; Xu, Bo; Liu, Po-Zi

    2016-01-01

    Blepharospasm (BSP) has a morbidity of 16 to 133 per million and is characterized by orbicularis oculi spasms. BSP can severely impact daily life. However, to date, its pathophysiology has not been clearly demonstrated. Near-infrared spectroscopy (NIRS) is a portable, non-invasive, and high time resolution apparatus used to measure cerebral blood flow. This study aimed to investigate the hemodynamic response patterns of BSP patients and determine whether BSP alone can be an attributional factor to influence the function of the prefrontal area using a verbal fluency task (VFT) and NIRS. Twenty-three BSP patients (10 males and 13 females) and 13 healthy controls (HC; five males and eight females) matched by gender and education were examined using NIRS. BSP patients were divided into two groups based on the presence or absence of depression and anxiety symptoms. A covariance analysis was conducted to analyze differences between the three groups and reduce the influence of different ages and educational levels. Bonferroni was used to process the post hoc test. The bilateral orbitofrontal area (ch36, 39, and 41; P<0.01) exhibited a lower activation in BSP patients without psychiatric symptoms compared with HC. This study is the first report to identify the prefrontal function in BSP using NIRS. Our findings indicate that BSP alone may cause a hypoactive hemodynamic performance in the prefrontal cortex in the absence of psychiatric symptoms. These findings provide evidence to support novel pathophysiological mechanisms of BSP. PMID:26942579

  11. Prefrontal Hemodynamic Functions during a Verbal Fluency Task in Blepharospasm Using Multi-Channel NIRS

    PubMed Central

    Zhang, Xiao-Qian; Liu, Xiao-Min; Ren, Xia-Jin; Ma, Xiang-Yun; Sun, Jing-Jing; Feng, Kun; Sun, Gao-Xiang; Xu, Bo; Liu, Po-Zi

    2016-01-01

    Blepharospasm (BSP) has a morbidity of 16 to 133 per million and is characterized by orbicularis oculi spasms. BSP can severely impact daily life. However, to date, its pathophysiology has not been clearly demonstrated. Near-infrared spectroscopy (NIRS) is a portable, non-invasive, and high time resolution apparatus used to measure cerebral blood flow. This study aimed to investigate the hemodynamic response patterns of BSP patients and determine whether BSP alone can be an attributional factor to influence the function of the prefrontal area using a verbal fluency task (VFT) and NIRS. Twenty-three BSP patients (10 males and 13 females) and 13 healthy controls (HC; five males and eight females) matched by gender and education were examined using NIRS. BSP patients were divided into two groups based on the presence or absence of depression and anxiety symptoms. A covariance analysis was conducted to analyze differences between the three groups and reduce the influence of different ages and educational levels. Bonferroni was used to process the post hoc test. The bilateral orbitofrontal area (ch36, 39, and 41; P<0.01) exhibited a lower activation in BSP patients without psychiatric symptoms compared with HC. This study is the first report to identify the prefrontal function in BSP using NIRS. Our findings indicate that BSP alone may cause a hypoactive hemodynamic performance in the prefrontal cortex in the absence of psychiatric symptoms. These findings provide evidence to support novel pathophysiological mechanisms of BSP. PMID:26942579

  12. Central hemodynamics in risk assessment strategies: additive value over and above brachial blood pressure.

    PubMed

    Yannoutsos, Alexandra; Rinaldi, Elisa R; Zhang, Yi; Protogerou, Athanassios D; Safar, Michel E; Blacher, Jacques

    2015-01-01

    Although the clinical relevance of brachial blood pressure (BP) measurement for cardiovascular (CV) risk stratification is nowadays widely accepted, this approach can nevertheless present several limitations. Pulse pressure (PP) amplification accounts for the notable increase in PP from central to peripheral arterial sites. Target organs are more greatly exposed to central hemodynamic changes than peripheral organs. The pathophysiological significance of local BP pulsatility, which has a role in the pathogenesis of target organ damage in both the macro- and the microcirculation, may therefore not be accurately captured by brachial BP as traditionally evaluated with cuff measurements. The predictive value of central systolic BP and PP over brachial BP for major clinical outcomes has been demonstrated in the general population, in elderly adults and in patients at high CV risk, irrespective of the invasive or non-invasive methods used to assess central BP. Aortic stiffness, timing and intensity of wave reflections, and cardiac performance appear as major factors influencing central PP. Great emphasis has been placed on the role of aortic stiffness, disturbed arterial wave reflections and their intercorrelation in the pathophysiological mechanisms of CV diseases as well as on their capacity to predict target organ damage and clinical events. Comorbidities and age-related changes, together with gender-related specificities of arterial and cardiac parameters, are known to affect the predictive ability of central hemodynamics on individual CV risk. PMID:25341861

  13. Noninvasive assessment of lower extremity hemodynamics in individuals with diabetes mellitus.

    PubMed

    Andersen, Charles A

    2010-09-01

    The timely and accurate noninvasive assessment of peripheral arterial disease (PAD) is a critical component of a limb preservation initiative in patients with diabetes mellitus. Noninvasive vascular studies (NIVS) can be useful in screening patients with diabetes for PAD. In patients with clinical signs or symptoms, NIVS provide crucial information on the presence, location, and severity of PAD, as well as an objective assessment of the potential for primary healing of an index wound or a surgical incision. Appropriately-selected NIVS are important in the decision-making process to determine whether and what type of intervention might be most appropriate, given the clinical circumstances. Hemodynamic monitoring is likewise very important following either an endovascular procedure or a surgical bypass. Surveillance studies, usually with a combination of physiologic testing and imaging with duplex ultrasound, accurately identify recurrent disease prior to the occurrence of thrombosis, allowing targeted reintervention. NIVS can be broadly grouped into three general categories: physiologic or hemodynamic measurements; anatomic imaging; and measurements of tissue perfusion. These types of tests and suggestions for their appropriate application in patients with diabetes are reviewed. PMID:20804937

  14. Noninvasive assessment of lower-extremity hemodynamics in individuals with diabetes mellitus.

    PubMed

    Andersen, Charles A

    2010-01-01

    The timely and accurate noninvasive assessment of peripheral arterial disease is a critical component of a limb preservation initiative in patients with diabetes mellitus. Noninvasive vascular studies can be useful in screening patients with diabetes for peripheral arterial disease. In patients with clinical signs or symptoms, noninvasive vascular studies provide crucial information on the presence, location, and severity of peripheral arterial disease and an objective assessment of the potential for primary healing of an index wound or a surgical incision. Appropriately selected noninvasive vascular studies are important in the decision-making process to determine whether and what type of intervention might be most appropriate given the clinical circumstances. Hemodynamic monitoring is likewise important after either an endovascular procedure or a surgical bypass. Surveillance studies, usually with a combination of physiologic testing and imaging with duplex ultrasound, accurately identify recurrent disease before the occurrence of thrombosis, allowing targeted reintervention. Noninvasive vascular studies can be broadly grouped into three general categories: physiologic or hemodynamic measurements, anatomical imaging, and measurements of tissue perfusion. These types of tests and suggestions for their appropriate application in patients with diabetes are reviewed. PMID:20847355

  15. Measurement system for an in-vitro characterization of the biomechanics and hemodynamics of arterial bifurcations

    NASA Astrophysics Data System (ADS)

    Suárez-Bagnasco, D.; Balay, G.; Cymberknop, L.; Armentano, R. L.; Negreira, C. A.

    2013-03-01

    Arterial behaviour in-vivo is influenced, amongst other factors, by the interaction between blood flow and the arterial wall endothelium, and the biomechanical properties of the arterial wall. This interaction plays an important role in pathogenic mechanisms of cardiovascular diseases such as atherosclerosis and arteriosclerosis. To quantify these interactions both from biomechanical and hemodynamical standpoints, a complete characterization and modelling of the arterial wall, blood flow, shear wall and circumferential wall stresses are needed. The development of a new multi-parameter measurement system (distances, pressures, flows, velocity profiles, temperature, viscosity) for an in-vitro characterization of the biomechanics and hemodynamics in arterial bifurcations (specially in carotid bifurcations) is described. This set-up represents an improvement relative to previous set-ups developed by the group FCIEN-FMED and is presently under development. Main subsystems interactions and environment-system interactions were identified and compensated to improve system's performance. Several interesting problems related with signal acquisition using a variety of sensors and some experimental results are shown and briefly discussed. Experimental data allow construction of meshes and parameter estimation of the biomechanical properties of the arterial wall, as well as boundary conditions, all suitable to be employed in CFD and FSI numerical simulation.

  16. Development of ultrasonic methods for hemodynamic measurements

    NASA Technical Reports Server (NTRS)

    Histand, M. B.; Miller, C. W.; Wells, M. K.; Mcleod, F. D.; Greene, E. R.; Winter, D.

    1975-01-01

    A transcutanous method to measure instantaneous mean blood flow in peripheral arteries of the human body was defined. Transcutanous and implanted cuff ultrasound velocity measurements were evaluated, and the accuracies of velocity, flow, and diameter measurements were assessed for steady flow. Performance criteria were established for the pulsed Doppler velocity meter (PUDVM), and performance tests were conducted. Several improvements are suggested.

  17. [A case of transient ischemic attack of hemodynamic origin induced by postprandial hypotension].

    PubMed

    Sakima, Hirokuni; Isa, Katsunori; Nakachi, Koh; Shiroma, Kanako; Tokashiki, Takashi; Ohya, Yusuke

    2014-01-01

    An 82-year-old man had a transient ischemic attack (TIA) with symptoms of consciousness disturbance and right hemiparesis while resting in a sitting position after breakfast. His symptoms improved around 1 h after onset when he lied in a supine position and received intravenous hydration. Duplex carotid ultrasonography revealed severe stenosis of the left common carotid artery. A decrease in the brain perfusion reserve was confirmed by acetazolamide-stress brain perfusion scintigraphy. Moreover, ambulatory blood pressure monitoring revealed a reduction in systolic blood pressure below 90 mmHg after each meal, indicating postprandial hypotension (PPH). The PPH was improved by oral administration of α-glucosidase inhibitor without any subsequent recurrences of TIA. The patient was diagnosed with TIA of hemodynamic origin that was induced by PPH and exhibited severe carotid stenosis. PPH is common in elderly people, and it should be recognized as a significant trigger for ischemic cerebrovascular disease. PMID:24583593

  18. Monitoring of cerebral hemodynamics during open-heart surgery in children using near-infrared intensity-modulated spectroscopy

    NASA Astrophysics Data System (ADS)

    Kohl-Bareis, Matthias; Watson, Russell W.; Chow, Gabriel; Roberts, Idris; Delpy, David T.; Cope, Mark

    1997-08-01

    Neurological impairments following cardiopulmonary bypass (CPB) during open heart surgery can result from microembolism and ischaemia. Here we present preliminary results from monitoring cerebral hemodynamics during CPB with near infrared intensity modulated spectroscopy. In particular, the study had two main objectives: (1) to monitor the oxy- and deoxy hemoglobin concentrations and their changes during the CPB surgery and (2) to monitor the transport scattering coefficient ((mu) s') of the brain especially during cooling and rewarming. A new method for the calculation of absolute absorption coefficients ((mu) a) was also tested. This method is based upon the monitoring of attenuation and phase changes that are induced by variations in absorption. These variations can be generated either by alterations in the tissue oxygenation or by injecting a dye (indocyanine green) into the CPB circuit. Absolute oxy- and deoxyhemoglobin concentrations and their changes during the CPB were calculated. The preliminary results suggest that cooling of the brain does not significantly alter (mu) s'.

  19. Lack of renal tubular and hemodynamic effects of non-selective and delta-opioid receptor antagonism.

    PubMed

    Barrett, R J; Turpin, J A; McGuirk, B A; Kau, S T

    1985-01-01

    The renal pharmacological actions of the non-selective opioid receptor antagonist naloxone and the selective delta (delta)-opioid receptor antagonist ICI 154,129 were examined in conscious dogs. Neither naloxone nor ICI 154,129 altered glomerular filtration rate, renal blood flow, blood pressure, heart rate, or renal excretion of water, Na+, K+, or Cl-. In addition, urine and plasma osmolality and electrolyte concentrations and hematocrit were unchanged, suggesting that neither agent produced physiologically significant alteration in plasma vasopressin levels. These data suggest that (a) naloxone and ICI 154,129 exert no renal pharmacological effects in dogs and (b) under resting physiological conditions, delta-opioid receptors, as well as other opioid receptor subtypes, probably are not involved in the tonic regulation of renal hemodynamics or tubular function. PMID:3983226

  20. Temporal hemodynamic effects of permissive hypercapnia associated with ideal PEEP in ARDS.

    PubMed

    Carvalho, C R; Barbas, C S; Medeiros, D M; Magaldi, R B; Lorenzi Filho, G; Kairalla, R A; Deheinzelin, D; Munhoz, C; Kaufmann, M; Ferreira, M; Takagaki, T Y; Amato, M B

    1997-11-01

    The associated use of permissive hypercapnia (PHY) and high PEEP levels (PEEP(IDEAL)) has been recently indicated as part of a lung-protective-approach (LPA) in acute respiratory distress syndrome (ARDS). However, the net hemodynamic effect produced by this association is not known. We analyzed the temporal hemodynamic effects of this combined strategy in 48 patients (mean age 34 +/- 13 yr) with ARDS, focusing on its immediate (after 1 h), early (first 36 h), and late (2nd-7th d) consequences. Twenty-five patients were submitted to LPA--with the combined use of permissive hypercapnia (PHY), VT < 6 ml/kg, distending pressures above PEEP < 20 cm H2O, and PEEP 2 cm H2O above the lower inflection point on the static inspiratory P-V curve (P(FLEX))- and 23 control patients were submitted to conventional mechanical ventilation. LPA was initiated at once, resulting in an immediate increase in heart rate (p = 0.0002), cardiac output (p = 0.0002), oxygen delivery (DO2l, p = 0.0003), and mixed venous Po2 (p = 0.0006), with a maintained systemic oxygen consumption (p = 0.52). The mean pulmonary arterial pressure markedly increased (mean increment 8.8 mm Hg; p < 0.0001), but the pulmonary vascular resistance did not change (p = 0.32). Cardiac filling pressures increased (p < 0.001) and the systemic vascular resistance fell (p = 0.003). All these alterations were progressively attenuated in the course of the first 36 h, despite persisting hypercapnia. Plasma lactate suffered a progressive decrement along the early period in LPA but not in control patients (p < 0.0001). No hemodynamic consequences of LPA were noticed in the late period and renal function was preserved. A multivariate analysis suggested that these acute hyperdynamic effects were related to respiratory acidosis, with no depressant effects ascribed to high PEEP levels. In contrast, high plateau pressures were associated with cardiovascular depression. Thus, as long as sufficiently low distending pressures are

  1. Changes in cerebral hemodynamics during a sleep-deprived video-electroencephalogram in healthy children.

    PubMed

    Peng, Bingwei; Li, Jialing; Wang, Jing; Liang, Xiuqiong; Zheng, Zhiying; Mai, Jianning

    2016-07-01

    This study investigates the cerebral hemodynamic changes during a routine sleep-deprived video-electroencephalogram (SD-VEEG) in healthy children. Forty-two children with normal intelligence were examined. The children were 5-14 years of age, and their electroencephalograms (EEGs) were within the normal range. Each subject was deprived of a routine night's sleep and then examined during non-drug-induced sleep in the daytime. The awake and sleep stages were evaluated using EEGs, according to the American Academy of Sleep Medicine. Stable transcranial Doppler ultrasound (TCD) tracings through real-time TCD-VEEG monitoring were recorded. The mean systolic cerebral blood flow velocity (CBFV), diastolic CBFV, pulsatility index and resistance index of each artery were analyzed for 30 s per stage. A multivariate analysis of variance was conducted to compare the hemodynamic parameters for the awake stage versus light sleep and deep sleep stages. Non-rapid eye movement sleep was associated with an increased CBFV in the middle (164.38  ±  27.28) and anterior cerebral artery (131.81  ±  21.55) during light sleep (stages N1 and N2) (P  =  0.0001), a reduced systolic CBFV in all vascular arteries (LMCA, 138.73  ±  20.64; LACA, 108.33  ±  22.33; LPCA, 83.9  ±  18.6) during deep sleep (stage N3) compared with light sleep (P  =  0.0001), and a sustained increased PI (LMCA, 0.92  ±  0.13; LACA, 0.964  ±  0.18) during deep sleep (P  <  0.05). These findings indicate distinct cerebral hemodynamic alterations during SD-VEEG in children. This study utilized real-time TCD-VEEG monitoring during SD-EEG to further investigate neurovascular coupling in interictal epileptic discharges and understand its potential influence on cognition in the developing brain. PMID:27244460

  2. The hemodynamic patterns in hypertensive men and women of different age.

    PubMed

    Krzesiński, P; Stańczyk, A; Gielerak, G; Piotrowicz, K

    2016-03-01

    Aging is associated with cardiovascular remodeling, which can be accelerated in arterial hypertension (AH). The aim of this study was to evaluate the relation between hemodynamic profile and age, as well as to identify the role of sex in hemodynamic patterns of aging in AH. The study comprised 326 patients with AH (mean age: 44.3 years). Two-dimensional echocardiography was performed to evaluate, that is, left ventricular diastolic dysfunction (LVDD) and ejection fraction (LVEF), and ICG to evaluate, that is, acceleration time index (ACI), velocity index (VI), total arterial compliance (TAC), systemic vascular resistance index (SVRI) and thoracic fluid content (TFC). The statistical analysis included interquartile comparison in subgroups of age <19-37 years (Q1), 38-44 years (Q2), 45-51 years (Q3) and 52-68 years (Q4). Aging was associated with: (1) higher prevalence of LVDD (Q1 vs Q4: 11.0% vs 24.7%, P=0.023); (2) altered LV systolic performance-ACI (81.4 vs 64.0 1/100 Ω s(-2), P=0.0001), VI (50.5 vs 42.8 1/1000 Ω s(-1), P=0.006), LVEF (65.4% vs 67.0%, NS); and (3) increased afterload-TAC (2.25 vs 1.87 ml mm Hg(-1), P=0.0001), SVRI (2182 vs 2407 dyn s m(2) cm(-)(5); P=0.045). The 'U-shaped' relation to age was observed for TFC. The above-mentioned hemodynamic trends were more pronounced in men, whereas females presented the 'middle-aged delay'. The influence of aging on cardiovascular system shows in progressive arterial stiffness and impaired left ventricular function. Thoracic fluid reduction may be compensatory to vasoconstriction but its efficiency declines with age. The patterns of cardiovascular aging are different in men and women. PMID:26134620

  3. Hemodynamic-impact-based prioritization of ventricular tachycardia alarms.

    PubMed

    Desai, Kalpit; Lexa, Michael; Matthews, Brett; Genc, Sahika

    2014-01-01

    Ventricular tachycardia (V-tach) is a very serious condition that occurs when the ventricles are driven at high rates. The abnormal excitation pathways make ventricular contraction less synchronous resulting in less effective filling and emptying of the left ventricles. However, almost half of the V-tach alarms declared through processing of patterns observed in electrocardiography are not clinically actionable. The focus of this study is to provide guidance on determining whether a technically-correct V-tach alarm is clinically-actionable by determining its "hemodynamic impact". A supervisory learning approach based on conditional inference trees to determine the hemodynamic impact of a V-tach alarm based on extracted features is described. According to preliminary results on a subset of Multiparameter intelligent monitoring in intensive care II (MIMIC-II) database, true positive rate of more than 90% can be achieved. PMID:25570734

  4. Arterial Stiffness, Central Pulsatile Hemodynamic Load, and Orthostatic Hypotension.

    PubMed

    Liu, Kai; Wang, Si; Wan, Shixi; Zhou, Yufei; Pan, Pei; Wen, Bo; Zhang, Xin; Liao, Hang; Shi, Di; Shi, Rufeng; Chen, Xiaoping; Jangala, Tulasiram

    2016-07-01

    The association between central pulsatile hemodynamic load, arterial stiffness, and orthostatic hypotension (OH) is unclear. The authors recruited 1099 participants from the community. Questionnaire, physical examination, and laboratory tests were performed. To assess the correlation between central pulsatile hemodynamic load, arterial stiffness, and OH, multiple logistic regression analysis was performed, and the discriminatory power was assessed by the area under the receiver operating curve. The prevalence of OH in this population was 5.6%. After adjusting for potential confounders, brachial-ankle pulse wave velocity (BaPWV) was significantly and positively correlated with OH in both the hypertension and nonhypertension groups (all P<.05), while central systolic blood pressure (CSBP) was only significantly associated with OH in the hypertension subgroup. In addition, BaPWV seemed to have a better discriminatory power than CSBP in both subgroups. BaPWV appears to be a better indicator of OH than CSBP in routine clinical practice. PMID:26543017

  5. Remote hemodynamic monitoring for ambulatory left ventricular assist device patients

    PubMed Central

    Emani, Sitaramesh

    2015-01-01

    Left ventricular assist devices (LVADs) have been shown to markedly improve survival and quality of life in patients with end-stage heart failure. However, despite ongoing improvements in survival and quality of life, significant challenges still exist in the management of these patients, including a high rate of recurrent heart failure and rehospitalizations. Similar challenges exist in the non-LVAD heart failure population as well, and recent efforts to utilize remote hemodynamic monitoring techniques to improve outcomes have shown promise. No data currently exist demonstrating extension of this benefit into the LVAD population, although a theoretical benefit can be extrapolated. Herein we review current remote hemodynamic methods and potential applications towards LVAD patients. PMID:26793337

  6. Optimal control of CPR procedure using hemodynamic circulation model

    DOEpatents

    Lenhart, Suzanne M.; Protopopescu, Vladimir A.; Jung, Eunok

    2007-12-25

    A method for determining a chest pressure profile for cardiopulmonary resuscitation (CPR) includes the steps of representing a hemodynamic circulation model based on a plurality of difference equations for a patient, applying an optimal control (OC) algorithm to the circulation model, and determining a chest pressure profile. The chest pressure profile defines a timing pattern of externally applied pressure to a chest of the patient to maximize blood flow through the patient. A CPR device includes a chest compressor, a controller communicably connected to the chest compressor, and a computer communicably connected to the controller. The computer determines the chest pressure profile by applying an OC algorithm to a hemodynamic circulation model based on the plurality of difference equations.

  7. Simulating Prosthetic Heart Valve Hemodynamics: Numerical Model Development

    NASA Astrophysics Data System (ADS)

    Ge, Liang

    2005-11-01

    Since the first successful implantation of a prosthetic heart valve four decades ago, over 50 different designs have been developed including both mechanical and bio-prosthetic valves. Valve implants, however, are associated with increased risk of blood clotting, a trend which is believed to be linked to the complex hemodynamics induced by the prosthesis. To understand prosthetic valve hemodynamics under physiological conditions, we develop a numerical method capable of simulating flows in realistic prosthetic heart valves in anatomical geometries. The method employs a newly developed hybrid numerical technique that integrates the chimera overset grid approach with a Cartesian, sharp-interface immersed boundary methodology. The capabilities of the method are demonstrated by applying it to simulate pulsatile flow in both bileaflet and tri-leaflet valves moving with prescribed leaflet kinematics.

  8. Biosimulation and visualization: effect of cerebrovascular geometry on hemodynamics.

    PubMed

    Oshima, Marie; Kobayashi, Toshio; Takagi, Kiyoshi

    2002-10-01

    Hemodynamics plays an important role in cardiovascular disorders, and the authors are applying numerical and experimental studies of cerebrovascular blood flow to the creation and rupture of cerebral aneurysms. In particular, this study aims to investigate the effects of cerebrovascular geometry on hemodynamics, such as flow pattern, wall shear stress distribution, and pressure. This report consists mainly of two parts: numerical study of blood flow in the artery extracted from computer tomography data, and numerical and experimental studies of a curved pipe model. The simulation was conducted by using a finite element method; the experiment was conducted by particle imaging velocimetry. Numerical and experimental results are compared and both show similar secondary flow behavior. PMID:12496038

  9. Coronary hemodynamic responses during local hemodilution in canine hearts

    SciTech Connect

    Crystal, G.J. )

    1988-03-01

    To evaluate the effect of hemodilution per se on coronary hemodynamics, experiments were performed in 36 anesthetized, open-chest dogs whose left anterior descending coronary artery (LAD) was perfused selectively with either normal arterial blood or arterial blood diluted with lactated Ringer solution. LAD blood flow (CBF) was measured with an electromagnetic flowmeter and its transmural distribution assessed with 15-{mu}m radioactive microspheres. With perfusion pressure normal, graded hemodilution caused progressive, transmurally uniform increases in CBF that showed an nonlinear relationship to inflow hematocrit. Increased peak reactive hyperemic flow and decreased dilator reserve ratio indicated that both reduced viscosity and vasodilation contributed to increased CBF during hemodilution. Hypotension alone reduced CBF, with greater effect in the subendocardium. Additional hemodilution returned CBF to normotensive value, but relative subendocardial hypoperfusion persisted. The present study provides fundamental information on effects of hemodilution on coronary hemodynamics without the systemic responses that complicated previous studies utilizing whole body exchange transfusions.

  10. Hemodynamics of distal revascularization-interval ligation.

    PubMed

    Illig, Karl A; Surowiec, Scott; Shortell, Cynthia K; Davies, Mark G; Rhodes, Jeffrey M; Green, Richard M

    2005-03-01

    Distal revascularization-interval ligation (DRIL) empirically corrects steal after arteriovenous fistula (AVF) creation in most cases, but because there is no topologic alteration in anatomy, it is unclear as to why it is effective. To explore this issue, nine symptomatic patients underwent intravascular pressure and flow measurements before and after DRIL following upper arm autologous AVFs. Mean pre-DRIL systolic pressure (mmHg; mean +/- SD) in the proximal brachial artery (PROX) was 102 +/- 17, while that at the AV anastomosis (AV ANAST) was 47 +/- 38 (p < 0.0006). Flow (mL/min) distal to AV ANAST was retrograde with the fistula open (-21 +/- 64) but became antegrade (58 +/- 29; p < 0.03) with occlusion of the fistula. Following DRIL, pressures at both PROX and AV ANAST sites did not change (104 +/- 24 and 51 +/- 43, respectively). However, pressure at the point at which the blood flow split to supply the hand or the fistula, now PROX, increased from 47 +/- 38 (pre-DRIL AV ANAST) to 104 +/- 24 (p < 0.0001). Pressure in the brachial artery distal to the ligature increased to 104 +/- 27 (p < 0.0001), flow at this point (to the hand) became antegrade (51 +/- 39; p < 0.03), and occlusion of the fistula did not significantly change pressure at this site. We hypothesize that improvement in hand perfusion following DRIL is due to a higher pressure at the point at which the blood flow splits to supply both hand and fistula (pre-DRIL: AV ANAST; post-DRIL: PROX), allowing antegrade flow down the new bypass to the lower pressure forearm. This increased pressure must be due to the increased resistance of the fistula created by interposing the arterial segment between the original AV ANAST and new PROX ANAST. As such, DRIL is schematically equivalent to banding, but resistance is increased in a fashion that is physiologically and empirically acceptable. PMID:15770367

  11. Influence of strut cross-section of stents on local hemodynamics in stented arteries

    NASA Astrophysics Data System (ADS)

    Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

    2016-05-01

    Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics (CFD) methods are performed to study how the shape and the aspect ratio (AR) of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress (WSS) in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

  12. Influence of strut cross-section of stents on local hemodynamics in stented arteries

    NASA Astrophysics Data System (ADS)

    Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

    2016-04-01

    Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics (CFD) methods are performed to study how the shape and the aspect ratio (AR) of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress (WSS) in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

  13. Distinct neurohumoral biomarker profiles in children with hemodynamically defined orthostatic intolerance may predict treatment options.

    PubMed

    Wagoner, Ashley L; Shaltout, Hossam A; Fortunato, John E; Diz, Debra I

    2016-02-01

    Studies of adults with orthostatic intolerance (OI) have revealed altered neurohumoral responses to orthostasis, which provide mechanistic insights into the dysregulation of blood pressure control. Similar studies in children with OI providing a thorough neurohumoral profile are lacking. The objective of the present study was to determine the cardiovascular and neurohumoral profile in adolescent subjects presenting with OI. Subjects at 10-18 yr of age were prospectively recruited if they exhibited two or more traditional OI symptoms and were referred for head-up tilt (HUT) testing. Circulating catecholamines, vasopressin, aldosterone, renin, and angiotensins were measured in the supine position and after 15 min of 70° tilt. Heart rate and blood pressure were continuously measured. Of the 48 patients, 30 patients had an abnormal tilt. Subjects with an abnormal tilt had lower systolic, diastolic, and mean arterial blood pressures during tilt, significantly higher levels of vasopressin during HUT, and relatively higher catecholamines and ANG II during HUT than subjects with a normal tilt. Distinct neurohumoral profiles were observed when OI subjects were placed into the following groups defined by the hemodynamic response: postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), syncope, and POTS/syncope. Key characteristics included higher HUT-induced norepinephrine in POTS subjects, higher vasopressin in OH and syncope subjects, and higher supine and HUT aldosterone in OH subjects. In conclusion, children with OI and an abnormal response to tilt exhibit distinct neurohumoral profiles associated with the type of the hemodynamic response during orthostatic challenge. Elevated arginine vasopressin levels in syncope and OH groups are likely an exaggerated response to decreased blood flow not compensated by higher norepinephrine levels, as observed in POTS subjects. These different compensatory mechanisms support the role of measuring neurohumoral

  14. Noninvasive monitoring hemodynamic responses in RIF tumors during and after PDT

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Durduran, Turgut; Busch, Theresa M.; Wang, Hsing-Wen; Zhou, Chao; Saunders, H. Mark; Sehgal, Chandra M.; Yodh, Arjun G.

    2003-06-01

    Changes in blood flow and oxygenation during and after PDT provide information about tumor vessel and cellular damage. The characterization of these changes may improve our understanding of PDT mechanisms and help predict treatment efficacy. We have designed a hybrid system that can non-invasively measure in vivo hemodynamic changes and provide independent information about tumor oxygenation and blood flow. Diffuse correlation spectroscopy (DCS) monitors blood flow by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave (DPDW) spectroscopy measures tissue absorption and scattering. When mounted on a camera, our unique probe allows non-contact measurements that avoid compressing the tumor and altering blood flow. An optical filter mounted in front of the camera lens cut off light below 650nm, which allowed monitoring of blood flow during PDT. The utility of the hybrid system was demonstrated by monitoring the hemodynamic changes during and after PDT in mice bearing the experimental radiation-induced fibrosarcoma (RIF). For the first time, we non-invasively and continually monitored the in vivo flow changes during PDT. Relative oxygen consumption was calculated using flow values measured by DCS and oxygenation measured by a broadband absorption spectrometer. During PDT an initial rapid increase in blood flow was found, followed by a decrease and slow recovery. After PDT, substantial and continued reductions in blood saturation, blood flow and oxygen consumption were found after 3 hours, suggesting that permanent damage to tumor cells and blood vessels had occurred. The comparison of flow values after PDT as measured by DCS and by Power Doppler ultrasound (CWFA) demonstrated that both techniques non-invasively detected similar global changes in tumor blood flow or perfusion after PDT.

  15. Hemodynamic evaluation of a chronically implanted, electrically powered left ventricular assist system: responses to acute circulatory stress.

    PubMed

    McKay, R G; Penny, W F; Wyman, R M; Clay, W; Carr, J G; Bernhard, W F; Grossman, W

    1991-12-01

    Hemodynamic stress testing was performed in four calves with a chronically implanted left ventricular assist device consisting of a double-valved pump interposed between the left ventricular apex and the descending thoracic aorta. The device was powered either pneumatically (n = 1) or with a transcutaneous energy transmission system (n = 3). Hemodynamic evaluation (cardiac output and right and left ventricular and pulmonary and carotid artery pressures) was carried out at baseline and during all hemodynamically stressed states. Atrial pacing and ventricular pacing to a heart rate of 140 beats/min resulted in no significant change in right or left heart filling pressures or cardiac output. Preload reduction with nitroprusside or transient inferior vena cava balloon occlusion resulted in a marked decrease in left ventricular pressure with preservation of mean arterial pressure. Phenylephrine administration resulted in a marked rise in mean arterial pressure with no change in cardiac output or filling pressure. Induction of ventricular fibrillation resulted in a decrease of mean left ventricular pressure to 11 +/- 8 mm Hg, but mean arterial pressure was maintained at greater than or equal to 50 mm Hg. It is concluded that a multicomponent, implantable, electrically powered assist system is capable of maintaining a normal cardiac output under a wide range of loading conditions and chronotropic states. Although this device is clearly preload dependent, it is capable of maintaining normal systemic pressures during conditions of severe left ventricular dysfunction and circulatory collapse. PMID:1960330

  16. Premedication effect of dexmedetomidine and alfentanil on seizure time, recovery duration, and hemodynamic responses in electroconvulsive therapy

    PubMed Central

    Moshiri, Esmail; Modir, Hesameddin; Bagheri, Niknam; Mohammadbeigi, Abolfazl; Jamilian, Hamidreza; Eshrati, Babak

    2016-01-01

    Introduction: Electroconvulsive therapy (ECT) is an effective treatment for many mental disorders, especially severe and persistent depression, bipolar disorder, and schizophrenia. The aim of this study is to compare the effect of dexmedetomidine and alfentanil on agitation, satisfaction, seizure duration, and patients hemodynamic after ECT. Materials and Methods: In a three phase crossover randomized clinical trial, 75 patients aged between 18 and 50 years and candidate for ECT were enrolled and assigned into three groups (25 patients in each group). All patients, respectively, took premedication of dexmedetomidine, alfentanil, or saline in three consecutive phases. Patients received 0.5 μg/kg dexmedetomidine, 10 μg/kg alfentanil or normal saline intravenously, 10 min before induction. Finally, seizure and recovery duration, satisfaction and agitation score, and hemodynamic parameters were evaluated. Results: There was no significant difference about seizure duration, agitation score, and hemodynamic parameters between groups but recovery duration was significantly lower in the control group than dexmedetomidine (P = 0.016) and alfentanil group (P = 0.0001). Patients’ satisfaction was significantly higher in intervention groups (alfentanil and dexmedetomidine groups) (P = 0.0001). Conclusion: Given the equal effects of alfentanil and dexmedetomidine, it seems that choosing one of these two drugs for premedication of patients undergoing ECT is appropriate. Drug choice is influenced by numerous factors such as accessibility of each drug and the dominance of anesthesiologist and psychiatrist. PMID:27052067

  17. Morphological and Hemodynamic Analysis of Mirror Posterior Communicating Artery Aneurysms

    PubMed Central

    Wu, Xi; Wu, Yongfa; Jiang, Che; Wang, Shengzhang; Huang, Qinghai; Liu, Jianmin

    2013-01-01

    Background and Purpose Hemodynamic factors are commonly believed to play an important role in the pathogenesis, progression, and rupture of cerebral aneurysms. In this study, we aimed to identify significant hemodynamic and morphological parameters that discriminate intracranial aneurysm rupture status using 3-dimensional-angiography and computational fluid dynamics technology. Materials and Methods 3D-DSA was performed in 8 patients with mirror posterior communicating artery aneurysms (Pcom-MANs). Each pair was divided into ruptured and unruptured groups. Five morphological and three hemodynamic parameters were evaluated for significance with respect to rupture. Results The normalized mean wall shear stress (WSS) of the aneurysm sac in the ruptured group was significantly lower than that in the unruptured group (0.52±0.20 versus 0.81±0.21, P = .012). The percentage of the low WSS area in the ruptured group was higher than that in the unruptured group (4.11±4.66% versus 0.02±0.06%, P = .018). The AR was 1.04±0.21 in the ruptured group, which was significantly higher than 0.70±0.17 in the unruptured group (P = .012). By contrast, parameters that had no significant differences between the two groups were OSI (P = .674), aneurysm size (P = .327), size ratio (P = .779), vessel angle (P = 1.000) and aneurysm inclination angle (P = 1.000). Conclusions Pcom-MANs may be a useful disease model to investigate possible causes of aneurysm rupture. The ruptured aneurysms manifested lower WSS, higher percentage of low WSS area, and higher AR, compared with the unruptured one. And hemodynamics is as important as morphology in discriminating aneurysm rupture status. PMID:23383184

  18. Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms

    PubMed Central

    Hua, Yufeng; Oh, Je Hoon

    2015-01-01

    Purpose The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms. Materials and Methods Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases. Results Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length. Conclusion Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms. PMID:26256976

  19. Experimental pathophysiology of systemic alterations induced by Bothrops asper snake venom.

    PubMed

    Gutiérrez, José María; Escalante, Teresa; Rucavado, Alexandra

    2009-12-01

    Moderate and severe envenomations by the snake Bothrops asper provoke systemic alterations, such as systemic bleeding, coagulopathy, hypovolemia, hemodynamic instability and shock, and acute renal failure. Systemic hemorrhage is a typical finding of these envenomations, and is primarily caused by the action of P-III snake venom metalloproteinases (SVMPs). This venom also contains a thrombin-like serine proteinase and a prothrombin-activating P-III SVMP, both of which cause defibrin(ogen)ation. Thrombocytopenia, predominantly induced by a C-type lectin-like protein, and platelet hypoaggregation, caused by the two defibrin(ogen)ating enzymes, also contribute to hemostatic disturbances, which potentiate the systemic bleeding induced by hemorrhagic SVMPs. Cardiovascular disturbances leading to shock are due to the combined effects of hemorrhagic toxins, other venom components that increase vascular permeability, the action of hypotensive agents in the venom and of endogenous mediators, and the potential cardiotoxic effect of some toxins. Renal alterations are likely to be caused by direct cytotoxicity of venom components in the kidney, and by renal ischemia resultant from hypovolemia and hypoperfusion. Lethality induced by B. asper venom is the consequence of several combined effects among which the action of P-III SVMPs is especially relevant. PMID:19303034

  20. Hemodynamic monitoring and management in patients undergoing high risk surgery: a survey among North American and European anesthesiologists

    PubMed Central

    2011-01-01

    Introduction Several studies have demonstrated that perioperative hemodynamic optimization has the ability to improve postoperative outcome in high-risk surgical patients. All of these studies aimed at optimizing cardiac output and/or oxygen delivery in the perioperative period. We conducted a survey with the American Society of Anesthesiologists (ASA) and the European Society of Anaesthesiology (ESA) to assess current hemodynamic management practices in patients undergoing high-risk surgery in Europe and in the United States. Methods A survey including 33 specific questions was emailed to 2,500 randomly selected active members of the ASA and to active ESA members. Results Overall, 368 questionnaires were completed, 57.1% from ASA and 42.9% from ESA members. Cardiac output is monitored by only 34% of ASA and ESA respondents (P = 0.49) while central venous pressure is monitored by 73% of ASA respondents and 84% of ESA respondents (P < 0.01). Specifically, the pulmonary artery catheter is being used much more frequently in the US than in Europe in the setup of high-risk surgery (85.1% vs. 55.3% respectively, P < 0.001). Clinical experience, blood pressure, central venous pressure, and urine output are the most widely indicators of volume expansion. Finally, 86.5% of ASA respondents and 98.1% of ESA respondents believe that their current hemodynamic management could be improved. Conclusions In conclusion, these results point to a considerable gap between the accumulating evidence about the benefits of perioperative hemodynamic optimization and the available technologies that may facilitate its clinical implementation, and clinical practices in both Europe and the United States. PMID:21843353

  1. Hemodynamics in pulmonary arterial hypertension (PAH): do they explain long-term clinical outcomes with PAH-specific therapy?

    PubMed Central

    2010-01-01

    Background Pulmonary arterial hypertension (PAH) has witnessed dramatic treatment advances over the past decade. However, with the exception of epoprostenol, data from short-term randomized controlled trials (RCTs) have not shown a benefit of these drugs on survival. There remains a need to differentiate between available therapies and current endpoint responses which in turn, could be used to guide treatment selection and provide long-term prognostic information for patients. Methods We performed a systematic literature search of MEDLINE and EMBASE databases for RCTs of PAH-specific therapy published between January 1980 and May 2009. Articles were selected if they contained a placebo comparator and described hemodynamic changes from baseline. We applied the weighted mean change in hemodynamic variables to the equation developed by the National Institutes of Health (NIH) Registry to estimate long-term survival with each therapy. Results Ten RCTs involving 1,635 patients met the inclusion criteria. Suitable hemodynamic data were identified for bosentan, sitaxentan, sildenafil, epoprostenol, beraprost and treprostinil. 77.6% of patients were female and the mean (SD) age was 46.5 ± 4.9 years. 55.5% of patients had idiopathic PAH (iPAH), 23.9% PAH related to connective tissue disease, and 18.2% PAH related to congenital heart disease. Based on the effects observed in short-term trials and, relative to placebo, all analyzed therapies improved survival. The estimated 1-year survival was 78.4%, 77.8%, 76.1%, 75.8%, 75.2%, and 74.1% for epoprostenol, bosentan, treprostinil, sitaxentan, sildenafil, and beraprost, respectively. These estimates are considerably lower than the 1-year observed survival reported in several open-label and registry studies with PAH-specific therapies: 88% - 97%. Conclusion When applied to the NIH Registry equation, hemodynamic changes from baseline appear to underestimate the survival benefits observed with long-term PAH therapy. PMID:20170553

  2. A study of the hemodynamics of anterior communicating artery aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan R.; Castro, Marcelo A.; Putman, Christopher M.

    2006-03-01

    In this study, the effects of unequal physiologic flow conditions in the internal carotid arteries on the intra-aneurysmal hemodynamics of anterior communicating artery aneurysms were investigated. Patient-specific vascular computational fluid dynamics models of five cerebral aneurysms were constructed from bilateral 3D rotational angiography images. The aneurysmal hemodynamics was analyzed under a range of physiologic flow conditions including the effects of unequal mean flows and phase shifts between the flow waveforms of the left and right internal carotid arteries. A total of five simulations were performed for each patient, and unsteady wall shear stress (WSS) maps were created for each flow condition. Time dependent curves of average WSS magnitude over selected regions on the aneurysms were constructed and used to analyze the influence of the inflow conditions. It was found that mean flow imbalances in the feeding vessels tend to shift the regions of elevated WSS (flow impingement region) towards the dominating inflow jet and to change the magnitude of the WSS peaks. However, the overall qualitative appearance of the WSS distribution and velocity simulations is not substantially affected. In contrast, phase differences tend to increase the temporal complexity of the hemodynamic patterns and to destabilize the intra-aneurysmal flow pattern. However, these effects are less important when the A1 confluence is less symmetric, i.e. dominated by one of the A1 segments. Conditions affecting the flow characteristics in the parent arteries of cerebral aneurysms with more than one avenue of inflow should be incorporated into flow models.

  3. Comparative hemodynamics in an aorta with bicuspid and trileaflet valves

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Sotiropoulos, Fotis

    2016-04-01

    Bicuspid aortic valve (BAV) is a congenital heart defect that has been associated with serious aortopathies, such as aortic stenosis, aortic regurgitation, infective endocarditis, aortic dissection, calcific aortic valve and dilatation of ascending aorta. There are two main hypotheses to explain the increase prevalence of aortopathies in patients with BAV: the genetic and the hemodynamic. In this study, we seek to investigate the possible role of hemodynamic factors as causes of BAV-associated aortopathy. We employ the curvilinear immersed boundary method coupled with an efficient thin-shell finite-element formulation for tissues to carry out fluid-structure interaction simulations of a healthy trileaflet aortic valve (TAV) and a BAV placed in the same anatomic aorta. The computed results reveal major differences between the TAV and BAV flow patterns. These include: the dynamics of the aortic valve vortex ring formation and break up; the large-scale flow patterns in the ascending aorta; the shear stress magnitude, directions, and dynamics on the heart valve surfaces. The computed results are in qualitative agreement with in vivo magnetic resonance imaging data and suggest that the linkages between BAV aortopathy and hemodynamics deserve further investigation.

  4. Hemodynamic patterns in shock and critically ill patients.

    PubMed

    Villazón, S A; Sierra, U A; López, S F; Rolando, M A

    1975-01-01

    Nine variables were studied in 56 patients to analyze hemodynamic patterns of critically ill and shock patients. The variables were central venous pressure, mean arterial pressure, heart rate, cardiac index, left ventricular stroke work, strok index, total peripheral resistance, arteriovenous oxygen difference, and oxygen consumption. We observed six patterns; three with low cardiac index (hypodynamic) and three with high cardiac index (hyperdynamic). Group IA: Low cardiac index with increased central venous pressure and arteriovenous oxygen differences associated with myocardial infarction, cardiac insufficiency, and postoperative cardiac surgery: Group IB: Low cardiac index with normal arteriovenous oxygen difference associated with myocardial infarction or hypovolemia. Group IC: Low cardiac index and decreased arteriovenous oxygen difference in patients with hypodynamic septic shock. Group IID: High cardiac index and increased arteriovenous oxygen difference in patients with sepsis and stable hemodynamic conditions. Groups IIE and IIF: Increased cardiac index and normal or increased arteriovenous oxygen difference in septic patients, who were hemodymamically unstable or in shock. These hemodynamic observations were found to be useful for understanding physiological compensations, for deciding on therapy, and in evaluating the effectiveness of therapy. PMID:1201657

  5. Quantifying the abnormal hemodynamics of sickle cell anemia

    NASA Astrophysics Data System (ADS)

    Lei, Huan; Karniadakis, George

    2012-02-01

    Sickle red blood cells (SS-RBC) exhibit heterogeneous morphologies and abnormal hemodynamics in deoxygenated states. A multi-scale model for SS-RBC is developed based on the Dissipative Particle Dynamics (DPD) method. Different cell morphologies (sickle, granular, elongated shapes) typically observed in deoxygenated states are constructed and quantified by the Asphericity and Elliptical shape factors. The hemodynamics of SS-RBC suspensions is studied in both shear and pipe flow systems. The flow resistance obtained from both systems exhibits a larger value than the healthy blood flow due to the abnormal cell properties. Moreover, SS-RBCs exhibit abnormal adhesive interactions with both the vessel endothelium cells and the leukocytes. The effect of the abnormal adhesive interactions on the hemodynamics of sickle blood is investigated using the current model. It is found that both the SS-RBC - endothelium and the SS-RBC - leukocytes interactions, can potentially trigger the vicious ``sickling and entrapment'' cycles, resulting in vaso-occlusion phenomena widely observed in micro-circulation experiments.

  6. Coronary hemodynamic responses during local hemodilution in canine hearts.

    PubMed

    Crystal, G J

    1988-03-01

    To evaluate the effect of hemodilution per se on coronary hemodynamics, experiments were performed in 36 anesthetized, open-chest dogs whose left anterior descending coronary artery (LAD) was perfused selectively with either normal arterial blood or arterial blood diluted with lactated Ringer solution. LAD blood flow (CBF) was measured with an electromagnetic flowmeter and its transmural distribution assessed with 15-microns radioactive microspheres. LAD perfusion pressure was set at the normal level (approximately 100 mmHg) or at 50% of that level to simulate coronary insufficiency. Dilator reserve capacity was calculated from ratio of reactive hyperemic peak flow following release of 90-s occlusion to control (preocclusion) flow. Systemic hemodynamic parameters were maintained near control values during coronary hemodilution. With perfusion pressure normal, graded hemodilution caused progressive, transmurally uniform increases in CBF that showed a nonlinear relationship to inflow hematocrit. Increased peak reactive hyperemic flow and decreased dilator reserve ratio indicated that both reduced viscosity and vasodilation contributed to increased CBF during hemodilution. Hypotension alone reduced CBF, with greater effect in the subendocardium. Additional hemodilution returned CBF to normotensive value, but relative subendocardial hypoperfusion persisted. The present study provides fundamental information on effects of hemodilution on coronary hemodynamics without the systemic responses that complicated previous studies utilizing whole body exchange transfusions. PMID:3348430

  7. 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. PMID:24436580

  8. Hemodynamic Responses to Speech and Music in Preverbal Infants

    PubMed Central

    Fava, Eswen; Hull, Rachel; Baumbauer, Kyle; Bortfeld, Heather

    2013-01-01

    Numerous studies have provided clues about the ontogeny of lateralization of auditory processing in humans, but most have employed specific subtypes of stimuli and/or have assessed responses in discrete temporal windows. The present study used near-infrared spectroscopy (NIRS) to establish changes in hemodynamic activity in the neocortex of preverbal infants (aged 4-11 months) while they were exposed to two distinct types of complex auditory stimuli (full sentences and musical phrases). Measurements were taken from bilateral temporal regions, including both anterior and posterior superior temporal gyri. When the infant sample was treated as a homogenous group, no significant effects emerged for stimulus type. However, when infants' hemodynamic responses were categorized according to their overall changes in volume, two very clear neurophysiological patterns emerged. A high responder group, showed a pattern of early and increasing activation, primarily in the left hemisphere, similar to that observed in comparable studies with adults. In contrast, a low responder group showed a pattern of gradual decreases inactivation over time. Although age did track with responder type, no significant differences between these groups emerged for stimulus type, suggesting that the high versus low responder characterization generalizes across classes of auditory stimuli. These results highlight a new way to conceptualize the variable cortical blood flow patterns that are frequently observed across infants and stimuli, with hemodynamic response volumes potentially serving as an early indicator of developmental changes in auditory processing sensitivity. PMID:23777481

  9. Dynamic cerebral autoregulation measured with coherent hemodynamics spectroscopy (CHS)

    NASA Astrophysics Data System (ADS)

    Kainerstorfer, Jana M.; Sassaroli, Angelo; Tgavalekos, Kristen T.; Fantini, Sergio

    2015-03-01

    Coherent Hemodynamics Spectroscopy (CHS) is a novel technique for non-invasive measurements of local microcirculation quantities such as the capillary blood transit times and dynamic autoregulation. The basis of CHS is to measure, for instance with near-infrared spectroscopy (NIRS), peripheral coherent hemodynamic changes that are induced by controlled perturbations in the systemic mean arterial pressure (MAP). In this study, the MAP perturbation was induced by the fast release of two pneumatic cuffs placed around the subject's thighs after they were kept inflated (at 200 mmHg) for two minutes. The resulting transient changes in cerebral oxy- (O) and deoxy- (D) hemoglobin concentrations measured with NIRS on the prefrontal cortex are then described by a novel hemodynamic model, from which quantifiable parameters such as the capillary blood transit time and a cutoff frequency for cerebral autoregulation are obtained. We present results on eleven healthy volunteers in a protocol involving measurements during normal breathing and during hyperventilation, which is known to cause a hypocapnia-induced increase in cerebral autoregulation. The measured capillary transit time was unaffected by hyperventilation (normal breathing: 1.1±0.1 s; hyperventilation: 1.1±0.1 s), whereas the cutoff frequency of autoregulation, which increases for higher autoregulation efficiency, was indeed found to be significantly greater during hyperventilation (normal breathing: 0.017±0.002 Hz; hyperventilation: 0.034±0.005 Hz). These results provide a validation of local cerebral autoregulation measurements with the new technique of CHS.

  10. Hemodynamic evaluation of transluminal iliac artery balloon dilatation.

    PubMed

    Breslau, P J; van Soest, M; Janevski, B; Jörning, P J

    1985-10-01

    In order to document the hemodynamic results of transluminal iliac artery balloon dilatation, 23 aortoiliac segments were evaluated before and after treatment. Hemodynamic parameters were: intra-arterial common femoral pressure measurements, indirect ankle pressure measurements and femoral velocity waveform analysis. The segments were divided into group (a) aortoiliac segments with an open superficial femoral artery (n = 8), and group (b) aortoiliac segments with an occluded superficial femoral artery (n = 15). In group (a) all patients were free of symptoms and ankle pressure improved significantly six months after dilatation. Velocity waveform analysis of the common femoral artery did not correlate with this improvement. In group (b) intra-arterial pressure measurements showed improvement in 60% (9/15) after six months. Ankle pressure measurements and velocity waveform analysis did not correlate with the intra-arterial pressure changes. Transluminal iliac artery balloon dilatation of iliac stenosis in patients with an open superficial femoral artery can be evaluated by indirect ankle pressure measurements. In patients with iliac stenosis in combination with occluded superficial femoral arteries intra-arterial pressure measurements are needed to demonstrate hemodynamic improvement. PMID:2932658

  11. Hemodynamic stroke: A rare pitfall in cranio cervical junction surgery

    PubMed Central

    Cornelius, Jan Frederick; Slotty, Philipp; El Khatib, Mustafa; Bostelmann, Richard; Hänggi, Daniel; Steiger, Hans Jakob

    2014-01-01

    Surgical C1C2-stabilization may be complicated by arterial-arterial embolism or arterial injury. Another potential complication is hemodynamic stroke. The latter might be induced in patients with poor posterior fossa collateralization (risk factor 1) when the vertebral artery (VA) is compressed during reduction (risk factor 2). We report a clinical case where this rare situation occurred: A 72-year old patient was undergoing C1C2-stabilization for subluxation due to rheumatoid arthritis. Preoperative computed tomography angiography (CTA) had shown poor collaterals in the posterior fossa. Furthermore, intraoperative Doppler ultrasound (US) detected unilateral VA occlusion during reduction. It appeared to be a high-risk situation for hemodynamic stroke. Surgical inspection of the VA found osteofibrous compressing elements. Arterial decompression was performed resulting in the normal flow as detected by US. Subsequently, C1C2-stabilization could be realized. The clinical and radiological outcome was very favorable. In C1C2-stabilization precise analysis of preoperative CTA and intraoperative US are important to detect risk factors of hemodynamic stroke. Using these data may prevent this rare, but potentially life-threatening complication. PMID:25336834

  12. Hemodynamic Characterization of Rodent Models of Pulmonary Arterial Hypertension.

    PubMed

    Ma, Zhiyuan; Mao, Lan; Rajagopal, Sudarshan

    2016-01-01

    Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle proliferation and obliteration of pulmonary arterioles. This in turn results in right ventricular (RV) failure, with significant morbidity and mortality. Rodent models of PAH, in the mouse and the rat, are important for understanding the pathophysiology underlying this rare disease. Notably, different models of PAH may be associated with different degrees of pulmonary hypertension, RV hypertrophy and RV failure. Therefore, a complete hemodynamic characterization of mice and rats with PAH is critical in determining the effects of drugs or genetic modifications on the disease. Here we demonstrate standard procedures for assessment of right ventricular function and hemodynamics in both rat and mouse PAH models. Echocardiography is useful in determining RV function in rats, although obtaining standard views of the right ventricle is challenging in the awake mouse. Access for right heart catheterization is obtained by the internal jugular vein in closed-chest mice and rats. Pressures can be measured using polyethylene tubing with a fluid pressure transducer or a miniature micromanometer pressure catheter. Pressure-volume loop analysis can be performed in the open chest. After obtaining hemodynamics, the rodent is euthanized. The heart can be dissected to separate the RV free wall from the left ventricle (LV) and septum, allowing an assessment of RV hypertrophy using the Fulton index (RV/(LV+S)). Then samples can be harvested from the heart, lungs and other tissues as needed. PMID:27167679

  13. Hemodynamics in an Aorta with Bicuspid and Trileaflet Valves

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Sotiropoulos, Fotis

    2015-11-01

    Bicuspid aortic valve (BAV) is a congenital heart defect that has been associated with serious aortopathies, such as ascending aortic aneurysm, aortic stenosis, aortic regurgitation, infective endocarditis, aortic dissection, calcific aortic valve and dilatation of ascending aorta. Two main hypotheses - the genetic and the hemodynamic are discussed in literature to explain the development and progression of aortopathies in patients with BAV. In this study we seek to investigate the possible role of hemodynamic factors as causes of BAV-associated aortopathy. We employ the Curvilinear Immersed Boundary (CURVIB) method coupled with an efficient thin-shell finite element (TS-FE) formulation for tissues to carry out fluid-structure interaction simulations of a healthy tri-leaflet aortic valve (TAV) and a BAV placed in the same anatomic aorta. The computed results reveal major differences between the TAV and BAV flow patterns. These include: the dynamics of the aortic valve vortex ring formation and break up; the large scale flow patterns in the ascending aorta; and the shear stress magnitude on the aortic wall. The computed results are in qualitative agreement with in vivo Magnetic Resonance Imaging (MRI) data and suggest that the linkages between BAV aortopathy and hemodynamics deserve further investigation. This work is supported by the Lillehei Heart Institute at the University of Minnesota and the Minnesota Supercomputing Institute.

  14. Hemodynamic responses to speech and music in preverbal infants.

    PubMed

    Fava, Eswen; Hull, Rachel; Baumbauer, Kyle; Bortfeld, Heather

    2014-01-01

    Numerous studies have provided clues about the ontogeny of lateralization of auditory processing in humans, but most have employed specific subtypes of stimuli and/or have assessed responses in discrete temporal windows. The present study used near-infrared spectroscopy (NIRS) to establish changes in hemodynamic activity in the neocortex of preverbal infants (aged 4-11 months) while they were exposed to two distinct types of complex auditory stimuli (full sentences and musical phrases). Measurements were taken from bilateral temporal regions, including both anterior and posterior superior temporal gyri. When the infant sample was treated as a homogenous group, no significant effects emerged for stimulus type. However, when infants' hemodynamic responses were categorized according to their overall changes in volume, two very clear neurophysiological patterns emerged. A high-responder group showed a pattern of early and increasing activation, primarily in the left hemisphere, similar to that observed in comparable studies with adults. In contrast, a low-responder group showed a pattern of gradual decreases in activation over time. Although age did track with responder type, no significant differences between these groups emerged for stimulus type, suggesting that the high- versus low-responder characterization generalizes across classes of auditory stimuli. These results highlight a new way to conceptualize the variable cortical blood flow patterns that are frequently observed across infants and stimuli, with hemodynamic response volumes potentially serving as an early indicator of developmental changes in auditory-processing sensitivity. PMID:23777481

  15. Altered fingerprints: analysis and detection.

    PubMed

    Yoon, Soweon; Feng, Jianjiang; Jain, Anil K

    2012-03-01

    The widespread deployment of Automated Fingerprint Identification Systems (AFIS) in law enforcement and border control applications has heightened the need for ensuring that these systems are not compromised. While several issues related to fingerprint system security have been investigated, including the use of fake fingerprints for masquerading identity, the problem of fingerprint alteration or obfuscation has received very little attention. Fingerprint obfuscation refers to the deliberate alteration of the fingerprint pattern by an individual for the purpose of masking his identity. Several cases of fingerprint obfuscation have been reported in the press. Fingerprint image quality assessment software (e.g., NFIQ) cannot always detect altered fingerprints since the implicit image quality due to alteration may not change significantly. The main contributions of this paper are: 1) compiling case studies of incidents where individuals were found to have altered their fingerprints for circumventing AFIS, 2) investigating the impact of fingerprint alteration on the accuracy of a commercial fingerprint matcher, 3) classifying the alterations into three major categories and suggesting possible countermeasures, 4) developing a technique to automatically detect altered fingerprints based on analyzing orientation field and minutiae distribution, and 5) evaluating the proposed technique and the NFIQ algorithm on a large database of altered fingerprints provided by a law enforcement agency. Experimental results show the feasibility of the proposed approach in detecting altered fingerprints and highlight the need to further pursue this problem. PMID:21808092

  16. Biosignal alterations generated by parabolic flights of small aerobatic aircrafts

    NASA Astrophysics Data System (ADS)

    Simon, M. Jose; Perez-Poch, Antoni; Ruiz, Xavier; Gavalda, Fina; Saez, Nuria

    Since the pioneering works of Prof. Strughold in 1948, the aerospace medicine aimed to characterize the modifications induced in the human body by changes in the gravity level. In this respect, it is nowadays well known that one of the most serious problems of these kind of environments is the fluid shift. If this effect is enough severe and persistent, serious changes in the hemodynamic of the brain (cerebral blood flow and blood oxigenation level) appear which could be detected as alterations in the electroencephalogram, EEG [1]. Also, this fluid redistribution, together with the relocation of the heart in the thorax, induces detectable changes in the electrocardiogram, ECG [2]. Other kind of important problems are related with vestibular instability, kinetosis and illusory sensations. In particular since the seventies [3,4] it is known that in parabolic flights and due to eye movements triggered by the changing input from the otholith system, fixed real targets appeared to have moved downward while visual afterimages appeared to have moved upward (oculogravic illusions). In order to cover all the above-mentioned potential alterations, the present work, together with the gravity level, continuously monitors the electroencephalogram, EEG, the electrocardiogram, ECG and the electrooculogram, EOG of a normal subject trying to detect correlations between the different alterations observed in these signals and the changes of gravity during parabolic flights. The small aerobatic aircraft used is a CAP10B and during the flight the subject is located near the pilot. To properly cover all the range of accelerations we have used two sensitive triaxial accelerometers covering the high and low ranges of acceleration. Biosignals have been gathered using a Biopac data unit together with the Acknowledge software package (from BionicÔ). It is important to finally remark that, due to the obvious difference between the power of the different engines, the accelerometric

  17. Characterization of early changes in fetoplacental hemodynamics in a diet-induced rabbit model of IUGR.

    PubMed

    López-Tello, J; Barbero, A; González-Bulnes, A; Astiz, S; Rodríguez, M; Formoso-Rafferty, N; Arias-Álvarez, M; Rebollar, P G

    2015-10-01

    Intrauterine growth restriction (IUGR) is associated with adverse perinatal outcomes and late-onset diseases in offspring. Eating disorders, voluntary caloric restriction and maternal undernutrition can all induce IUGR but a relevant model is required to measure all its possible consequences. In this work, pregnant rabbits were used as an IUGR model. Control females (n=4) received ad libitum diet throughout pregnancy, whereas underfed females (n=5) were restricted to 50% of their daily requirements. Offspring size was measured by ultrasonography and in vivo at birth. Hemodynamic features of the umbilical cords and middle cerebral arteries (systolic peak velocity, end diastolic velocity, pulsatility index and resistance index) were characterized by Doppler ultrasonography. At day 21, maternal underfeeding resulted in a significant reduction of fetal size (occipito-nasal length). At birth, the size of kits from the underfed group was significantly lower (lower crown-rump length, biparietal and transversal thoracic diameters) and a reduced weight with respect to the control group. Feed restriction altered blood flow perfusion compared with does fed ad libitum (significant higher systolic peak, time-averaged mean velocities and lower end diastolic velocity). Fetuses affected by IUGR presented with compensative brain-sparing effects when compared with the control group. In conclusion, the present study supports using rabbits and the underfeeding approach as a valuable model for IUGR studies. These results may help to characterize IUGR alterations due to nutrient restriction of mothers in future research. PMID:26268616

  18. Hemodynamics in the mouse aortic arch as assessed by MRI, ultrasound, and numerical modeling.

    PubMed

    Feintuch, Akiva; Ruengsakulrach, Permyos; Lin, Amy; Zhang, Ji; Zhou, Yu-Qing; Bishop, Jonathon; Davidson, Lorinda; Courtman, David; Foster, F Stuart; Steinman, David A; Henkelman, R Mark; Ethier, C Ross

    2007-02-01

    Mice are widely used to study arterial disease in humans, and the pathogenesis of arterial diseases is known to be strongly influenced by hemodynamic factors. It is, therefore, of interest to characterize the hemodynamic environment in the mouse arterial tree. Previous measurements have suggested that many relevant hemodynamic variables are similar between the mouse and the human. Here we use a combination of Doppler ultrasound and MRI measurements, coupled with numerical modeling techniques, to characterize the hemodynamic environment in the mouse aortic arch at high spatial resolution. We find that the hemodynamically induced stresses on arterial endothelial cells are much larger in magnitude and more spatially uniform in the mouse than in the human, an effect that can be explained by fluid mechanical scaling principles. This surprising finding seems to be at variance with currently accepted models of the role of hemodynamics in atherogenesis and the known distribution of atheromatous lesions in mice. PMID:17012350

  19. Severe Bradycardia During Neurosurgical Procedure: Depth of Anesthesia Matters and Leads to a New Surrogate Model of the Trigeminocardiac Reflex: A Case Report.

    PubMed

    Chowdhury, Tumul; Ahuja, Nitin; Schaller, Bernhard

    2015-12-01

    Hemodynamic alterations are observed in various neurosurgical procedures and commonly related to different neurogenic mechanisms. However, anesthetic influences on causation of these perturbations or management are rarely investigated and therefore our present knowledge is still limited.In this case of 43-old Caucasian male, propofol boluses aborted the trigeminal cardiac reflex (TCR) induced severe bradycardia during dural manipulation. There is a correlation of severity of bradycardia and slightness of anesthesia.In the light of the larger distribution of the TCR all over the world, we see more and more aborted TCR, as seen in the present case; then the neuro-anesthesists more and more recognize the TCR at its very onset. A surrogate model for the daily use is present to underline the clinical needs.We have therefore developed, for the first time, a surrogate model that helps in daily practice to recognize and prevent TCR episodes. PMID:26656339

  20. Hemodynamic signals in fNIRS.

    PubMed

    Hoshi, Y

    2016-01-01

    Near-infrared spectroscopy (NIRS) was originally designed for clinical monitoring of tissue oxygenation, and it has also been developed into a useful tool in neuroimaging studies, with the so-called functional NIRS (fNIRS). With NIRS, cerebral activation is detected by measuring the cerebral hemoglobin (Hb), where however, the precise correlation between NIRS signal and neural activity remains to be fully understood. This can in part be attributed to the situation that NIRS signals are inherently subject to contamination by signals arising from extracerebral tissue. In recent years, several approaches have been investigated to distinguish between NIRS signals originating in cerebral tissue and signals originating in extracerebral tissue. Selective measurements of cerebral Hb will enable a further evolution of fNIRS. This chapter is divided into six sections: first a summary of the basic theory of NIRS, NIRS signals arising in the activated areas, correlations between NIRS signals and fMRI signals, correlations between NIRS signals and neural activities, and the influence of a variety of extracerebral tissue on NIRS signals and approaches to this issue are reviewed. Finally, future prospects of fNIRS are described. PMID:27130415

  1. Severe Weather

    ERIC Educational Resources Information Center

    Forde, Evan B.

    2004-01-01

    Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This article deals with a poster entitled, "Severe Weather," that has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in…

  2. Severe Weather

    ERIC Educational Resources Information Center

    Forde, Evan B.

    2004-01-01

    Educating the public about safety issues related to severe weather is part of the National Oceanic and Atmospheric Administration's (NOAA) mission. This month's insert, Severe Weather, has been created by NOAA to help educate the public about hazardous weather conditions. The four types of severe weather highlighted in this poster are hurricanes,…

  3. The Effect of Sorafenib, Tadalafil and Macitentan Treatments on Thyroxin-Induced Hemodynamic Changes and Cardiac Abnormalities

    PubMed Central

    Saad, Nancy S.; Floyd, Kyle; Ahmed, Amany A. E.; Mohler, Peter J.

    2016-01-01

    Multikinase inhibitors (e.g. Sorafenib), phosphodiesterase-5 inhibitors (e.g. Tadalafil), and endothelin-1 receptor blockers (e.g. Macitentan) exert influential protection in a variety of animal models of cardiomyopathy; however, their effects on thyroxin-induced cardiomyopathy have never been investigated. The goal of the present study was to assess the functional impact of these drugs on thyroxin-induced hemodynamic changes, cardiac hypertrophy and associated altered responses of the contractile myocardium both in-vivo at the whole heart level and ex-vivo at the cardiac tissue level. Control and thyroxin (500 μg/kg/day)-treated mice with or without 2-week treatments of sorafenib (10 mg/kg/day; I.P), tadalafil (1 mg/kg/day; I.P or 4 mg/kg/day; oral), macitentan (30 and 100 mg/kg/day; oral), and their vehicles were studied. Blood pressure, echocardiography and electrocardiogram were non-invasively evaluated, followed by ex-vivo assessments of isolated multicellular cardiac preparations. Thyroxin increased blood pressure, resulted in cardiac hypertrophy and left ventricular dysfunction in-vivo. Also, it caused contractile abnormalities in right ventricular papillary muscles ex-vivo. None of the drug treatments were able to significantly attenuate theses hemodynamic changes or cardiac abnormalities in thyroxin-treated mice. We show here for the first time that multikinase (raf1/b, VEGFR, PDGFR), phosphodiesterase-5, and endothelin-1 pathways have no major role in thyroxin-induced hemodynamic changes and cardiac abnormalities. In particular, our data show that the involvement of endothelin-1 pathway in thyroxine-induced cardiac hypertrophy/dysfunction seems to be model-dependent and should be carefully interpreted. PMID:27082116

  4. Hemodynamic measurements in rat brain and human muscle using diffuse near-infrared absorption and correlation spectroscopies

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Durduran, Turgut; Furuya, D.; Lech, G.; Zhou, Chao; Chance, Britten; Greenberg, J. H.; Yodh, Arjun G.

    2003-07-01

    Measurement of concentration, oxygenation, and flow characteristics of blood cells can reveal information about tissue metabolism and functional heterogeneity. An improved multifunctional hybrid system has been built on the basis of our previous hybrid instrument that combines two near-infrared diffuse optical techniques to simultaneously monitor the changes of blood flow, total hemoglobin concentration (THC) and blood oxygen saturation (StO2). Diffuse correlation spectroscopy (DCS) monitors blood flow (BF) by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave spectroscopy (DPDW) measures tissue absorption and scattering. Higher spatial resolution, higher data acquisition rate and higher dynamic range of the improved system allow us to monitor rapid hemodynamic changes in rat brain and human muscles. We have designed two probes with different source-detector pairs and different separations for the two types of experiments. A unique non-contact probe mounted on the back of a camera, which allows continuous measurements without altering the blood flow, was employed to in vivo monitor the metabolic responses in rat brain during KCl induced cortical spreading depression (CSD). A contact probe was used to measure changes of blood flow and oxygenation in human muscle during and after cuff occlusion or exercise, where the non-contact probe is not appropriate for monitoring the moving target. The experimental results indicate that our multifunctional hybrid system is capable of in vivo and non-invasive monitoring of the hemodynamic changes in different tissues (smaller tissues in rat brain, larger tissues in human muscle) under different conditions (static versus moving). The time series images of flow during CSD obtained by our technique revealed spatial and temporal hemodynamic changes in rat brain. Two to three fold longer recovery times of flow and oxygenation after cuff occlusion or exercise from calf flexors in a

  5. Hemodynamic Study of TCPC Using In Vivo and In Vitro 4D Flow MRI and Numerical Simulation

    PubMed Central

    Roldán-Alzate, Alejandro; García-Rodríguez, Sylvana; Anagnostopoulos, Petros V.; Srinivasan, Shardha; Wieben, Oliver; François, Christopher J.

    2015-01-01

    Altered total cavopulmonary connection (TCPC) hemodynamics can cause long-term complications. Patient-specific anatomy hinders generalized solutions. 4D Flow MRI allows in vivo assessment, but not predictions under varying conditions and surgical approaches. Computational fluid dynamics (CFD) improves understanding and explores varying physiological conditions. This study investigated a combination of 4D Flow MRI and CFD to assess TCPC hemodynamics, accompanied with in vitro measurements as CFD validation. 4D Flow MRI was performed in extracardiac and atriopulmonary TCPC subjects. Data was processed for visualization and quantification of velocity and flow. Three-dimensional (3D) geometries were generated from angiography scans and used for CFD and physical model construction through additive manufacturing. These models were connected to a perfusion system, circulating water through the vena cavae and exiting through the pulmonary arteries at two flow rates. Models underwent 4D Flow MRI and image processing. CFD simulated the in vitro system, applying two different inlet conditions from in vitro 4D Flow MRI measurements; no-slip was implemented at rigid walls. Velocity and flow were obtained and analyzed. The three approaches showed similar velocities, increasing proportionally with high inflow. Atriopulmonary TCPC presented higher vorticity compared to extracardiac at both inflow rates. Increased inflow balanced flow distribution in both TCPC cases. Atriopulmonary IVC flow participated in atrium recirculation, contributing to RPA outflow; at baseline, IVC flow preferentially travelled through the LPA. The combination of patient-specific in vitro and CFD allows hemodynamic parameter control, impossible in vivo. Physical models serve as CFD verification and fine-tuning tools. PMID:25841292

  6. The Effect of Sorafenib, Tadalafil and Macitentan Treatments on Thyroxin-Induced Hemodynamic Changes and Cardiac Abnormalities.

    PubMed

    Saad, Nancy S; Floyd, Kyle; Ahmed, Amany A E; Mohler, Peter J; Janssen, Paul M L; Elnakish, Mohammad T

    2016-01-01

    Multikinase inhibitors (e.g. Sorafenib), phosphodiesterase-5 inhibitors (e.g. Tadalafil), and endothelin-1 receptor blockers (e.g. Macitentan) exert influential protection in a variety of animal models of cardiomyopathy; however, their effects on thyroxin-induced cardiomyopathy have never been investigated. The goal of the present study was to assess the functional impact of these drugs on thyroxin-induced hemodynamic changes, cardiac hypertrophy and associated altered responses of the contractile myocardium both in-vivo at the whole heart level and ex-vivo at the cardiac tissue level. Control and thyroxin (500 μg/kg/day)-treated mice with or without 2-week treatments of sorafenib (10 mg/kg/day; I.P), tadalafil (1 mg/kg/day; I.P or 4 mg/kg/day; oral), macitentan (30 and 100 mg/kg/day; oral), and their vehicles were studied. Blood pressure, echocardiography and electrocardiogram were non-invasively evaluated, followed by ex-vivo assessments of isolated multicellular cardiac preparations. Thyroxin increased blood pressure, resulted in cardiac hypertrophy and left ventricular dysfunction in-vivo. Also, it caused contractile abnormalities in right ventricular papillary muscles ex-vivo. None of the drug treatments were able to significantly attenuate theses hemodynamic changes or cardiac abnormalities in thyroxin-treated mice. We show here for the first time that multikinase (raf1/b, VEGFR, PDGFR), phosphodiesterase-5, and endothelin-1 pathways have no major role in thyroxin-induced hemodynamic changes and cardiac abnormalities. In particular, our data show that the involvement of endothelin-1 pathway in thyroxine-induced cardiac hypertrophy/dysfunction seems to be model-dependent and should be carefully interpreted. PMID:27082116

  7. Effect of naringin on hemodynamic changes and left ventricular function in renal artery occluded renovascular hypertension in rats

    PubMed Central

    Visnagri, Asjad; Adil, Mohammad; Kandhare, Amit D.; Bodhankar, Subhash L.

    2015-01-01

    Background: Renal artery occlusion (RAO) induced hypertension is a major health problem associated with structural and functional variations of the renal and cardiac vasculature. Naringin a flavanone glycoside derived possesses metal-chelating, antioxidant and free radical scavenging properties. Objective: The objective of this study was to investigate the antihypertensive activity of naringin in RAO induced hypertension in rats. Material and Methods: Male Wistar rats (180-200 g) were divided into five groups Sham, RAO, naringin (20, 40 and 80 mg/kg). Animals were pretreated with naringin (20, 40 and 80 mg/kg p.o) for 4 weeks. On the last day of the experiment, left renal artery was occluded with renal bulldog clamp for 4 h. After assessment of hemodynamic and left ventricular function various biochemical (superoxide dismutase [SOD], glutathione [GSH] and malondialdehyde [MDA]) and histological parameters were determined in the kidney. Results: RAO group significantly (P < 0.001) increased hemodynamic parameters at 15, 30 and 45 min of clamp removal. Naringin (40 and 80 mg/kg) treated groups showed a significant decrease in hemodynamic parameters at 15 min. after clamp removal that remained sustained for 60 min. Naringin (40 and 80 mg/kg) treated groups showed significant improvement in left ventricular function at 15, 30 and 45 min after clamp removal. Alteration in level of SOD, GSH and MDA was significantly restored by naringin (40 and 80 mg/kg) treatment. It also reduced histological aberration induced in kidney by RAO. Conclusion: It is concluded that the antihypertensive activity of naringin may result through inhibition of oxidative stress. PMID:25883516

  8. Comparison of hemodynamic and metabolic stress responses caused by endotracheal tube and Proseal laryngeal mask airway in laparoscopic cholecystectomy

    PubMed Central

    Güleç, Handan; Çakan, Türkay; Yaman, Halil; Kilinç, Aytül Şadan; Başar, Hülya

    2012-01-01

    Background: We aimed to compare hemodynamic and endocrine alterations caused by stress response due to Proseal laryngeal mask airway and endotracheal tube usage in laparoscopic cholecystectomy. Materials and Methods: Sixty-three ASA I-II patients scheduled for elective laparoscopic cholecystectomy were included in the study. Patients were randomly allocated into two groups of endotracheal tube and Proseal laryngeal mask airway. Standard general anaesthesia was performed in both groups with the same drugs in induction and maintenance of anaesthesia. After anaesthesia induction and 20 minutes after CO2 insufflations, venous blood samples were obtained for measuring adrenalin, noradrenalin, dopamine and cortisol levels. Hemodynamic and respiratory parameters were recorded at the 1st, 5th, 15th, 30th and 45th minutes after the insertion of airway devices. Results: No statistically significant differences in age, body mass index, gender, ASA physical status, and operation time were found between the groups (p > 0.05). Changes in hemodynamic and respiratory parameters were not statistically significant when compared between and within groups (p > 0.05). Although no statistically significant differences were observed between and within groups when adrenalin, noradrenalin and dopamine values were compared, serum cortisol levels after CO2 insufflation in PLMA group were significantly lower than the ETT group (p = 0.024). When serum cortisol levels were compared within groups, cortisol levels 20 minutes after CO2 insufflation were significantly higher (46.1 (9.5-175.7) and 27.0 (8.3-119.4) in the ETT and PLMA groups, respectively) than cortisol levels after anaesthesia induction (11.3 (2.8-92.5) and 16.6 (4.4-45.4) in the ETT and PLMA groups, respectively) in both groups (p = 0.001). Conclusion: PLMA usage is a suitable, effective and safe alternative to ETT in laparoscopic cholecystectomy patients with lower metabolic stress. PMID:23264788

  9. [EFFECTS OF XENON ANESTHESIA ON HEMODYNAMICS: WHAT DO WE KNOW UNTIL 2015? (REVIEW)].

    PubMed

    Kulikov, A Yu; Kuleshov, O V; Lebedinskii, K M

    2015-01-01

    Xenon is known as an anesthetic in many ways closer to the ideal. In recent years, despite a number of objective reasons limiting its widespread use, the search continues for understanding how xenon influences on central hemodynamic parameters and regional blood flow. Analysis of several dozen of modern articles revealed many differences between the earlier and present data, emphasizing the prospect offurther research. According to Russian authors Xe has a positive inotropic effect on the myocardium and increases cardiac output. Foreign researchers in animal experiments notice vasoconstrictor properties of Xe with increased vascular resistance in the systemic and pulmonary circulation. The place of Xe as an anesthetic in the anesthetist's arsenal yet to be seen. PMID:27025141

  10. The cerebral hemodynamics of normotensive hypovolemia during lower-body negative pressure

    NASA Technical Reports Server (NTRS)

    Giller, C. A.; Levine, B. D.; Meyer, Y.; Buckey, J. C.; Lane, L. D.; Borchers, D. J.

    1992-01-01

    Although severe hypovolemia can lead to hypotension and neurological decline, many patients with neurosurgical disorders experience a significant hypovolemia while autonomic compensatory mechanisms maintain a normal blood pressure. To assess the effects of normotensive hypovolemia upon cerebral hemodynamics, transcranial Doppler ultrasound monitoring of 13 healthy volunteers was performed during graded lower-body negative pressure of up to -50 mm Hg, an accepted laboratory model for reproducing the physiological effects of hypovolemia. Middle cerebral artery flow velocity declined by 16% +/- 4% (mean +/- standard error of the mean) and the ratio between transcranial Doppler ultrasound pulsatility and systemic pulsatility rose 22% +/- 8%, suggesting cerebral small-vessel vasoconstriction in response to the sympathetic activation unmasked by lower-body negative pressure. This vasoconstriction may interfere with the autoregulatory response to a sudden fall in blood pressure, and may explain the common observation of neurological deficit during hypovolemia even with a normal blood pressure.

  11. A black-box decomposition approach for coupling heterogeneous components in hemodynamics simulations.

    PubMed

    Blanco, Pablo J; Leiva, Jorge S; Buscaglia, Gustavo C

    2013-03-01

    This work presents a generic and efficient black-box approach for the strong iterative coupling of dimensionally heterogeneous flow models in computational hemodynamics. A heterogeneous model of the cardiovascular system is formed by several vascular black-box components, which are connected through coupling equations. The associated system of equations is solved using the Broyden algorithm. In addition, a multiple time-stepping strategy is introduced to meet different component requirements. The proposed algorithm is employed to split a 3D-1D-0D closed-loop model of the cardiovascular system into corresponding black-box components standing for the 3D (specific vessels), 1D (systemic arteries/peripheral vessels), and 0D (venous/cardiac/pulmonary circulation) components. Examples of application are presented showing the robustness and suitability of this novel approach. PMID:23345261

  12. Effects of Hemodynamic Forces on the Vascular Differentiation of Stem Cells: Implications for Vascular Graft Engineering

    NASA Astrophysics Data System (ADS)

    Diop, Rokhaya; Li, Song

    Although the field of vascular tissue engineering has made tremendous advances in the past decade, several complications have yet to be overcome in order to produce biocompatible small-diameter vascular conduits with long-term patency. Stem cells and progenitor cells represent potential cell sources in the development of autologous (or allogeneic), nonthrombogenic vascular grafts with mechanical properties comparable to native blood vessel. However, a better understanding of the effects of mechanical forces on stem cells and progenitor cells is needed to properly utilize these cells for tissue engineering applications. In this chapter, we discuss the current understanding of the effects of hemodynamic forces on the differentiation and function of adult stem cells, embryonic stem cells, and progenitor cells. We also review the use of stem cells and progenitor cells in vascular graft engineering.

  13. Physiological responses to environmental factors related to space flight. [hemodynamic and metabolic responses to weightlessness

    NASA Technical Reports Server (NTRS)

    Pace, N.

    1973-01-01

    Physiological base line data are established, and physiological procedures and instrumentation necessary for the automatic measurement of hemodynamic and metabolic parameters during prolonged periods of weightlessness are developed.

  14. Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study.

    PubMed

    Delannoy, Bertrand; Wallet, Florent; Maucort-Boulch, Delphine; Page, Mathieu; Kaaki, Mahmoud; Schoeffler, Mathieu; Alexander, Brenton; Desebbe, Olivier

    2016-01-01

    Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients. PMID:27127648

  15. Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

    PubMed Central

    Delannoy, Bertrand; Wallet, Florent; Maucort-Boulch, Delphine; Page, Mathieu; Kaaki, Mahmoud; Schoeffler, Mathieu; Alexander, Brenton; Desebbe, Olivier

    2016-01-01

    Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients. PMID:27127648

  16. Hemodynamic analysis of renal artery stenosis using computational fluid dynamics technology based on unenhanced steady-state free precession magnetic resonance angiography: preliminary results.

    PubMed

    Zhang, Weisheng; Qian, Yi; Lin, Jiang; Lv, Peng; Karunanithi, Kaavya; Zeng, Mengsu

    2014-02-01

    This study aims to evaluate the feasibility of computational fluid dynamics (CFD) technology in analysis of renal artery stenosis (RAS) based on unenhanced MR angiography (MRA). Thirty hypertensive patients with unilateral RAS, and 10 normal volunteers, underwent unenhanced MRA on a 1.5 T MR scanner. 12 of 30 patients also underwent ultrasound (US) to detect peak systolic velocity. The patient-specific CFD based on MRA was carried out thereafter. Stenosis grades and hemodynamic variables at the stenosis of main renal artery, including pressure difference (PD), velocity and mass flow rate (MFR), were analysed. And the hemodynamic indices of stenoses were compared with the parameters of normal renal arteries and available US velocity profile. High intraclass correlation coefficient (value 0.995) and no significant difference (p > 0.05) was shown between maximum velocity of CFD and peak systolic velocity of US in 12 patients. For normal renal arteries, the average PD, velocity and MFR were all in the reported normal physiological range. However, for stenotic arteries, the translesional PD and velocity of main renal arteries increased with the severity of stenotic degrees, while the MFR decreased. 50 % diameter stenosis was the threshold at which all three hemodynamic parameters experienced significant changes (p < 0.01). This preliminary study shows that unenhanced-MRA-based CFD can be utilized to noninvasively analyse hemodynamic parameters of RAS. The acquired variables may provide meaningful information regarding stratification of the stenosis and further therapeutic treatment. PMID:24318538

  17. Validation and Visualization of Two-Dimensional Optical Spectroscopic Imaging of Cerebral Hemodynamics

    PubMed Central

    Sheth, Sameer A.; Prakash, Neal; Guiou, Michael; Toga, Arthur W.

    2009-01-01

    Perfusion-based functional brain imaging techniques such as fMRI and optical intrinsic signal (OIS) imaging are becoming increasingly important in both neuroscience research and intraoperative brain mapping. Recent studies have applied a spectroscopic approach to OIS imaging data, which we will call “two-dimensional optical spectroscopy” (2DOS), generating images of functional changes in hemoglobin oxygenation and blood volume. This improvement comes at the cost of several assumptions. Whereas the “gold standard” technique of fiber spectroscopy decomposes reflected light over a spectral axis, 2DOS retains both spatial dimensions by acquiring images at several wavelengths, sacrificing spectral resolution for the extra spatial dimension. Furthermore, 2DOS data are acquired interleaved within or between trials, but combined during the spectroscopic analysis as if acquired simultaneously. Thus far, the few studies employing this approach have assumed both that the reduced spectral resolution is tolerable, and that sufficient trial averaging can compensate for the temporally staggered data acquisition. To test these assumptions, we compared 2DOS results to those produced by traditional fiber spectroscopy by observing the hemodynamic response to hindpaw electrical stimulation over the primary somatosensory cortex in anesthetized rats. Comparisons revealed low fitting residuals and a high level of correlation between the two, but noteworthy differences in response magnitudes. Inspection of individual timecourses revealed a lower signal-to-noise ratio for 2DOS data. For visualization and interpretation of the 2DOS images, we present a parameterized visualization strategy, in which oxy-, deoxy-, and total hemoglobin are assigned to individual color channels. The resulting composite image conveniently displays the evolution of hemodynamic responses through parenchymal and vascular compartments in space and time. PMID:19013531

  18. Inappropriate intracranial hemodynamics in the natural course of MELAS.

    PubMed

    Nishioka, Junko; Akita, Yukihiro; Yatsuga, Shuichi; Katayama, Koujyu; Matsuishi, Toyojiro; Ishibashi, Masatoshi; Koga, Yasutoshi

    2008-02-01

    The abnormalities of intracranial hemodynamics associated with strokelike episodes in MELAS are variable depend on the time phase from the onset of strokelike episodes and on the progression of the dementia state. To clarify the regional cerebral blood flows (rCBF) in the natural course of MELAS is very important to understand the pathogenic mechanism of this disorder, either cytopathy, angiopathy or both. We analyzed the serial studies of brain statistical parametric mapping (SPM) 99 single photon emission computed tomography (SPECT) in 5 MELAS patients in maximum 10 years interval, who fulfilled the clinical, pathological and genetic criteria of MELAS, and have an A3243G mutation in the mitochondrial tRNA(Leu(UUR)) gene. SPM is a proven and effective method for the voxel-by-voxel analysis of functional images which show the advantage in its promise of fully automated neurophysiological imaging analysis throughout the whole brain using various statistical analyses. SPECT acquisition was initiated and was reconstructed by iterative algorithm and were processed and analyzed with SPM 99 for Windows software. Statistics were displayed as Z scores (threshold: P < 0.01). The inappropriate intracranial hemodynamics was found not only at the acute but at the interictal phase, and was getting worse as the disease progress. Hypoperfusion in the posterior cingulate cortex was always observed (corrected P < 0.01) in MELAS patients, which is the typical finding reported in Alzheimer's disease. The inappropriate intracranial hemodynamics is a common feature and may be related with mitochondrial angiopathy in the natural course of MELAS. PMID:17664050

  19. Computational study of anterior communicating artery hemodynamics before aneurysm formation

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2012-03-01

    It is widely accepted that complexity in the flow pattern at the anterior communicating artery (AComA) is associated with the high rate of aneurysm formation in that location observed in large studies. A previous computational hemodynamic study showed a possible association between high maximum intraaneurysmal wall shear stress (WSS) at the systolic peak with rupture in a cohort of AComA aneurysms. In another study it was observed a connection between location of aneurysm blebs and regions of high WSS in models where blebs were virtually removed. However, others reported associations between low WSS and either rupture or blister formation. The purpose of this work is to study associations between hemodynamic patterns and AComA aneurysm initiation by comparing hemodynamics in the aneurysm and the normal model where the aneurysm was computationally removed. Vascular models of both right and left circulation were independently reconstructed from three-dimensional rotational angiography images using deformable models, and fused using a surface merging algorithm. The geometric models were then used to generate high-quality volumetric finite element grids of tetrahedra with an advancing front technique. For each patient, the second anatomical model was created by digitally removing the aneurysm. It was iteratively achieved by applying a Laplacian smoothing filter and remeshing the surface. Finite element blood flow numerical simulations were performed. It was observed that aneurysms initiated in regions of high and moderate WSS in the counterpart normal models. Adjacent or close to those regions, low WSS portions of the arterial wall were not affected by the disease.

  20. Ischemic preconditioning reduces hemodynamic response during metaboreflex activation.

    PubMed

    Mulliri, Gabriele; Sainas, Gianmarco; Magnani, Sara; Palazzolo, Girolamo; Milia, Nicola; Orrù, Andrea; Roberto, Silvana; Marongiu, Elisabetta; Milia, Raffaele; Crisafulli, Antonio

    2016-05-01

    Ischemic preconditioning (IP) has been shown to improve exercise performance and to delay fatigue. However, the precise mechanisms through which IP operates remain elusive. It has been hypothesized that IP lowers the sensation of fatigue by reducing the discharge of group III and IV nerve endings, which also regulate hemodynamics during the metaboreflex. We hypothesized that IP reduces the blood pressure response during the metaboreflex. Fourteen healthy males (age between 25 and 48 yr) participated in this study. They underwent the following randomly assigned protocol: postexercise muscle ischemia (PEMI) test, during which the metaboreflex was elicited after dynamic handgrip; control exercise recovery session (CER) test; and PEMI after IP (IP-PEMI) test. IP was obtained by occluding forearm circulation for three cycles of 5 min spaced by 5 min of reperfusion. Hemodynamics were evaluated by echocardiography and impedance cardiography. The main results were that after IP the mean arterial pressure response was reduced compared with the PEMI test (means ± SD +3.37 ± 6.41 vs. +9.16 ± 7.09 mmHg, respectively). This was the consequence of an impaired venous return that impaired the stroke volume during the IP-PEMI more than during the PEMI test (-1.43 ± 15.35 vs. +10.28 ± 10.479 ml, respectively). It was concluded that during the metaboreflex, IP affects hemodynamics mainly because it impairs the capacity to augment venous return and to recruit the cardiac preload reserve. It was hypothesized that this is the consequence of an increased nitric oxide production, which reduces the possibility to constrict venous capacity vessels. PMID:26936782

  1. Wall Mechanical Properties and Hemodynamics of Unruptured Intracranial Aneurysms

    PubMed Central

    Cebral, Juan R.; Duan, Xinjie; Chung, Bong Jae; Putman, Christopher; Aziz, Khaled; Robertson, Anne

    2016-01-01

    Purpose To investigate the relationship between the intra-aneurysmal hemodynamic conditions and the mechanical properties of the wall in human aneurysms. Methods A total of eight unruptured aneurysms were analyzed. Computational fluid dynamics (CFD) models were constructed from pre-operative 3D rotational angiography images. The aneurysms were clipped and the domes were resected and mechanically tested to failure with a uniaxial testing system under multi-photon microscopy. Linear regression analysis was performed to explore possible correlations between hemodynamic quantities and the failure characteristics and stiffness of the wall. Results The ultimate strain was negatively correlated to aneurysm inflow rate (p=0.021), mean velocity (p=0.025), and mean wall shear stress (p=0.039). It was also negatively correlated to inflow concentration, oscillatory shear index and measures of the complexity and instability of the flow; however these trends did not reach statistical significance. The wall stiffness at high strains was positively correlated to inflow rate (p=0.014), mean velocity (p=0.008), inflow concentration (p=0.04), flow instability (p=0.006), flow complexity (p=0.019), wall shear stress (p=0.002) and oscillatory shear index (p=0.004). Conclusions In a study of 8 unruptured intracranial aneurysms, ultimate strain is negatively correlated with aneurysm inflow rate, mean velocity and mean wall shear stress. Wall stiffness is positively correlated with aneurysm inflow rate, mean velocity, wall shear stress, flow complexity and stability, and oscillatory shear index. These trends and the impact of hemodynamics on wall structure and mechanical properties should be further investigated in larger studies. PMID:26228891

  2. Human bulbar conjunctival hemodynamics in hemoglobin SS and SC disease

    PubMed Central

    Wanek, Justin; Gaynes, Bruce; Lim, Jennifer I.; Molokie, Robert; Shahidi, Mahnaz

    2014-01-01

    The known biophysical variations of hemoglobin (Hb) S and Hb C may result in hemodynamic differences between subjects with SS and SC disease. The purpose of this study was to measure and compare conjunctival hemodynamics between subjects with Hb SS and SC hemoglobinopathies. Image sequences of the conjunctival microcirculation were acquired in 9 healthy control subjects (Hb AA), 24 subjects with SC disease, and 18 subjects with SS disease, using a prototype imaging system. Diameter (D) and blood velocity (V) measurements were obtained in multiple venules of each subject. Data were categorized according to venule caliber by averaging V and D for venules with diameters less than (vessel size 1) or greater than (vessel size 2) 15 µm. V in vessel size 2 was significantly greater than V in vessel size 1 in the AA and SS groups (P ≥ 0.009), but not in the SC group (P = 0.1). V was significantly lower in the SC group as compared to the SS group (P = 0.03). In AA and SS groups, V correlated with D (P ≥ 0.005), but the correlation was not statistically significant in the SC group (P = 0.08). V was inversely correlated with hematocrit in the SS group for large vessels (P = 0.03); however, no significant correlation was found in the SC group (P ≥ 0.2). Quantitative assessment of conjunctival microvascular hemodynamics in SS and SC disease may advance understanding of sickle cell disease pathophysiology and thereby improve therapeutic interventions. PMID:23657867

  3. Central and regional hemodynamics in prolonged space flights

    NASA Astrophysics Data System (ADS)

    Gazenko, O. G.; Shulzhenko, E. B.; Turchaninova, V. F.; Egorov, A. D.

    This paper presents the results of measuring central and regional (head, forearm, calf) hemodynamics at rest and during provocative tests by the method of tetrapolar rheography in the course of Salyut-6-Soyuz and Salyut-7-Soyuz missions. The measurements were carried out during short-term (19 man-flights of 7 days in duration) and long-term (21 man-flights of 65-237 days in duration) manned missions. At rest, stroke volume (SV) and cardiac output (CO) as well as heart rate (HR) decreased insignificantly (in short-term flights) or remained essentially unchanged (in long-term flights). In prolonged flights CO increased significantly in response to exercise tests due to an increase in HR and the lack of changes in SV. After exercise tests SV and CO decreased as compared to the preflight level. During lower body negative pressure (LBNP) tests HR and CO were slightly higher than preflight. Changes in regional hemodynamics included a distinct decrease of pulse blood filling (PBF) of the calf, a reduction of the tone of large vessels of the calf and small vessels of the forearm. Head examination (in the region of the internal carotid artery) showed a decrease of PBF of the left hemisphere (during flight months 2-8) and a distinct decline of the tone of small vessels, mainly, in the right hemisphere. During LBNP tests the tone of pre- and postcapillary vessels of the brain returned to normal while PBF of the right and left hemisphere vessels declined. It has been shown that regional circulation variations depend on the area examined and are induced by a rearrangement of total hemodynamics of the human body in microgravity. This paper reviews the data concerning changes in central and regional circulation of men in space flights of different duration.

  4. Current and Potential Therapeutic Strategies for Hemodynamic Cardiorenal Syndrome

    PubMed Central

    Obi, Yoshitsugu; Kim, Taehee; Kovesdy, Csaba P.; Amin, Alpesh N.; Kalantar-Zadeh, Kamyar

    2016-01-01

    Background Cardiorenal syndrome (CRS) encompasses conditions in which cardiac and renal disorders co-exist and are pathophysiologically related. The newest classification of CRS into seven etiologically and clinically distinct types for direct patient management purposes includes hemodynamic, uremic, vascular, neurohumoral, anemia- and/or iron metabolism-related, mineral metabolism-related and protein-energy wasting-related CRS. This classification also emphasizes the pathophysiologic pathways. The leading CRS category remains hemodynamic CRS, which is the most commonly encountered type in patient care settings and in which acute or chronic heart failure leads to renal impairment. Summary This review focuses on selected therapeutic strategies for the clinical management of hemodynamic CRS. This is often characterized by an exceptionally high ratio of serum urea to creatinine concentrations. Loop diuretics, positive inotropic agents including dopamine and dobutamine, vasopressin antagonists including vasopressin receptor antagonists such as tolvaptan, nesiritide and angiotensin-neprilysin inhibitors are among the pharmacologic agents used. Additional therapies include ultrafiltration (UF) via hemofiltration or dialysis. The beneficial versus unfavorable effects of these therapies on cardiac decongestion versus renal blood flow may act in opposite directions. Some of the most interesting options for the outpatient setting that deserve revisiting include portable continuous dobutamine infusion, peritoneal dialysis and outpatient UF via hemodialysis or hemofiltration. Key Messages The new clinically oriented CRS classification system is helpful in identifying therapeutic targets and offers a systematic approach to an optimal management algorithm with better understanding of etiologies. Most interventions including UF have not shown a favorable impact on outcomes. Outpatient portable dobutamine infusion is underutilized and not well studied. Revisiting traditional and

  5. Hemodynamic support with percutaneous devices in patients with heart failure.

    PubMed

    Kapur, Navin K; Esposito, Michele

    2015-04-01

    The use of surgically implanted durable mechanical circulatory support (MCS) in high-risk patients with heart failure is declining and short-term, nondurable MCS device use is growing. Percutaneously delivered MCS options for advanced heart failure include the intra-aortic balloon pump, Impella axial flow catheter, TandemHeart centrifugal pump, and venoarterial extracorporeal membrane oxygenation. Nondurable MCS devices have unique implantation characteristics and hemodynamic effects. Algorithms and guidelines for optimal nondurable MCS device selection do not exist. Emerging technologies and applications will address the need for improved left ventricular unloading using lower-profile devices, longer-term ambulatory support, and the potential for myocardial recovery. PMID:25834971

  6. Effects of Dietary Nitrates on Systemic and Cerebrovascular Hemodynamics

    PubMed Central

    Curry, Bryan H.; Adams, Richard G.; Asadi, M. Sadegh; Millis, Richard M.; Haddad, Georges E.

    2013-01-01

    Cerebral blood flow dysregulation is often associated with hypertension. We hypothesized that a beetroot juice (BRJ) treatment could decrease blood pressure and cerebrovascular resistance (CVR). We subjected 12 healthy females to control and BRJ treatments. Cerebrovascular resistance index (CVRI), systolic blood pressure (SBP), total vascular resistance (TVR), and the heart rate-systolic pressure product (RPP) measured at rest and at two exercise workloads were lower after the BRJ treatment. CVRI, SBP, and RPP were lower without a lower TVR at the highest exercise level. These findings suggest improved systemic and cerebral hemodynamics that could translate into a dietary treatment for hypertension. PMID:24455404

  7. [Hemodynamic response to cotton allergen exposure in the industrial environment].

    PubMed

    Bakuleva, N S; Usol'tsev, B G; Orlova, O A

    1983-03-01

    The methods of functional diagnosis (mechanocardiography, rheoencephalography) were used to examine the responses of the central and craniocerebral hemodynamics to inhalations of specific cotton allergens in female workers of a textile factory with different grades of sensitization. It was discovered that both the initial level and response pattern on the part of the cardiovascular system and craniocerebral circulation depend to a certain measure on the level of background reactivity. The data obtained enable prognosing the status of the cardiovascular system and taking measures aimed at its correction in subjects sensitized to cotton dust, who continue working in cotton industry. PMID:6830989

  8. From hemodynamic towards cardiomechanic sensors in implantable devices

    NASA Astrophysics Data System (ADS)

    Ferek-Petric, Bozidar

    2013-06-01

    Sensor could significantly improve the cardiac electrotherapy. It has to provide long-term stabile signal not impeding the device longevity and lead reliability. It may not introduce special implantation and adjustment procedures. Hemodynamic sensors based on the blood flow velocity and cardiomechanic sensors based on the lead bending measurement are disclosed. These sensors have a broad clinical utility. Triboelectric and high-frequency lead bending sensors yield accurate and stable signals whereby functioning with every cardiac lead. Moreover, high frequency measurement avoids use of any kind of special hardware mounted on the cardiac lead.

  9. Relationships between hemodynamic, hemorheological and metabolic responses during exercise.

    PubMed

    Connes, Philippe; Tripette, Julien; Mukisi-Mukaza, Martin; Baskurt, Oguz K; Toth, Kalman; Meiselman, Herbert J; Hue, Olivier; Antoine-Jonville, Sophie

    2009-01-01

    Aerobic performance is dependent on both cardio-respiratory and peripheral factors with hemodynamic parameters playing a major role. However, whether blood rheology might affect aerobic performance through an effect on hemodynamic factors is not known. The aim of the present study was to assess the relationships between hemodynamic, hemorheological and metabolic parameters in response to a sub-maximal cycling exercise protocol consisting of three successive levels of nine min duration (50, 100 and 150 W). Ten young sportsmen participated in the present study. Mean arterial pressure (MAP) was measured manually, with thoracic impedance used to monitor cardiac output (Qc): systemic vascular resistance (SVR) was then calculated. Whole blood viscosity (etab) was measured and used to calculate systemic vascular hindrance. Hematocrit (Hct) was determined by micro-centrifugation and red blood cell (RBC) deformability (EI) was determined by ecktacytometry. A breath-by-breath gas analyzer was used to measure oxygen uptake (VO2); the Fick equation was used to calculate arterio-venous oxygen difference [(a-v)O(2)] from VO(2) and Qc. All measurements were performed at rest, during exercise and during recovery. Compared to baseline, Qc, MAP, Hct, EI, VO(2), and (a-v)O(2) increased during exercise. etab increased above baseline only at 150 W and remained elevated during recovery; the increase in etab during the last level of exercise was associated with a decrease of SVR and systemic vascular hindrance. There was a significant negative correlation between EI and SVR (r=-0.35, p<0.01) and a significant positive relationship between EI and (a-v)O(2) (r=0.35, p<0.01) and between EI and VO(2) (r=0.37, p<0.01) across all exercise workloads, thus suggesting a potential role for RBC deformability as a factor affecting aerobic performance via oxygen delivery to tissues. These data lend support to the concept that hemorheological parameters may contribute to hemodynamic and cardio

  10. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude.

    PubMed

    Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng

    2016-01-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (-17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution. PMID:27503416

  11. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liu, Yang; Ren, Li-Hua; Li, Li; Wang, Zhen; Liu, Shan-Shan; Li, Su-Zhi; Cao, Tie-Sheng

    2016-08-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (‑17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution.

  12. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude

    PubMed Central

    Liu, Jie; Liu, Yang; Ren, Li-hua; Li, Li; Wang, Zhen; Liu, Shan-shan; Li, Su-zhi; Cao, Tie-sheng

    2016-01-01

    To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (−17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution. PMID:27503416

  13. Isolation and characterization of a set of disease resistance-gene analogs (RGAs) from wild rice, Zizania latifolia Griseb. I. Introgression, copy number lability, sequence change, and DNA methylation alteration in several rice-Zizania introgression lines.

    PubMed

    Chen, Yu; Long, Likun; Lin, Xiuyun; Guo, Wanli; Liu, Bao

    2006-02-01

    Eight resistance-gene analogs (RGAs) were isolated from wild rice, Zizania latifolia Griseb., by degenerate primers designed according to conserved motifs at or around the nucleotide-binding site (NBS) of known NBS-containing plant resistance genes. The 8 RGAs were classified into 6 distinct groups based on their deduced amino acid sequence similarity of 60% or greater. Gel-blot hybridization of each of the RGAs to 4 rice - Z. latifolia intro gression lines indicated an array of changes at either introgressed Zizania RGAs or, more likely, their rice homologs. The changes included dramatic increase in copy number, modification at the primary DNA sequence, and alteration in DNA methylation patterns. PMID:16498465

  14. Alteration of fatal 1:1 conducted atrial flutter to less conducted ratio by landiolol infusion.

    PubMed

    Takata, Junko; Haruyama, Naoko; Arashi, Tomoko; Mae, Tomoko

    2016-08-01

    An 84-year-old male patient with a past history of atrial-flutter-fibrillation and dementia underwent an urgent femoral neck fracture surgery. Preoperative electrocardiography demonstrated atrial flutter (AFL) with ventricular conduction at a ratio of 2:1-4:1, and transthoracic echocardiography showed severe left ventricular dysfunction with Ejection Fraction of 14.6 %. Femoral nerve block and Lateral femoral cutaneous nerve block with sedation was planned for the surgery. Upon entry to the operating room, ECG showed 2:1 conducted AFL at the rate of 128 beats min(-1). Due to the stimulation of urethral catheter insertion, it has altered to 1:1 conducted AFL. Loading dose of landiolol hydrochloride 7.5 mg followed by 1.5-3 μg/kg/min continuous administration was given, which had decreased the conduction ratio to 2:1 without causing hypotension. A further episode of 1:1 conducted AFL occurred when the pin was inserted to the thighbone, which caused circulatory collapse. Additional bolus dose of landiolol immediately altered it to 2:1 before operating cardioversion and stabilized the hemodynamics. He maintained AFL with 2:1 conduction thereafter, and 1:1 conduction was never seen postoperatively even after discontinuation of landiolol. PMID:27085543

  15. Sever's Disease

    MedlinePlus

    ... Tests How do I know if my child's heel pain is caused by Sever's disease? In Sever's disease, heel pain can be in one or both heels. It ... cut down or stop any activity that causes heel pain. Apply ice to the injured heel for 20 ...

  16. Widespread hemodynamic depression and focal platelet accumulation after fluid percussion brain injury: a double-label autoradiographic study in rats.

    PubMed

    Dietrich, W D; Alonso, O; Busto, R; Prado, R; Dewanjee, S; Dewanjee, M K; Ginsberg, M D

    1996-05-01

    Cerebrovascular damage leading to subsequent reductions in local cerebral blood flow (lCBF) may represent an important secondary injury mechanism following traumatic brain injury (TBI). We determined whether patterns of 111-indium-labeled platelet accumulation were spatially related to alterations in lCBF determined autoradiographically 30 min after TBI. Sprague-Dawley rats (n = 8), anesthetized with halothane and maintained on a 70:30 (vol/vol) mixture of nitrous oxide/oxygen and 0.5% halothane, underwent parasagittal fluid percussion brain injury (1.7-2.2 atm). 111-Indium-tropolone-labeled platelets were injected 30 min prior to TBI while [14C]-iodoantipyrine was infused 30 min after trauma. Sham-operated animals (n = 7) underwent similar surgical procedures but were not injured. In autoradiographic images of the indium-labeled platelets, focal sites of platelet accumulation within the traumatized hemisphere were restricted to the pial surface (five of eight rats), the external capsule underlying the lateral parietal cortex (five of eight rats), and within cerebrospinal fluid (CSF) compartments (six of eight rats). In contrast, mild-to-moderate reductions in lCBF, not restricted to sites of platelet accumulation, were seen throughout the traumatized hemisphere. Flow reductions were most severe in coronal sections underlying the impact site. For example, within the lateral parietal cortex and hippocampus, lCBF was significantly reduced [p <0.01; analysis of variance (ANOVA)] from 1.71 +/- 0.34 (mean +/- SD) and 0.78 +/- 0.12 ml/g/min, respectively, versus 0.72 +/- 0.17 and 0.41 +/- 0.06 ml/g/min within the traumatized hemisphere. Significant flow reductions were also seen in remote cortical and subcortical areas, including the right frontal cortex and striatum. These results indicate that focal platelet accumulation and widespread hemodynamic depression are both early consequences of TBI. Therapeutic strategies directed at these early microvascular consequences of

  17. Severe Sarcoidosis.

    PubMed

    Kouranos, Vasileios; Jacob, Joe; Wells, Athol U

    2015-12-01

    In sarcoidosis, reduction in mortality and the prevention of disability due to major organ involvement are treatment goals. Thus, it is important to recognize severe disease and identify patients at higher risk of progression to severe disease. In this article, fibrotic lung disease and cardiac sarcoidosis are reviewed as the major contributors to sarcoidosis mortality and morbidity. In the absence of a standardized definition of severe pulmonary disease, a multidisciplinary approach to clinical staging is suggested, based on symptoms, pulmonary function tests, and imaging findings at presentation, integrated with the duration of disease and longitudinal disease behavior during early follow-up. PMID:26593144

  18. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications

    PubMed Central

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  19. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications.

    PubMed

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee; Yang, Dong Hyun; Kim, Namkug

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  20. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics

    NASA Astrophysics Data System (ADS)

    Anupindi, Kameswararao; Delorme, Yann; Shetty, Dinesh A.; Frankel, Steven H.

    2013-12-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high-order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. (2010) [33]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of fluid flow patterns that exist in pathological

  1. Numerical analysis of the effect of turbulence transition on the hemodynamic parameters in human coronary arteries

    PubMed Central

    Gawandalkar, Udhav Ulhas; Kini, Girish; Buradi, Abdulrajak; Araki, Tadashi; Ikeda, Nobutaka; Nicolaides, Andrew; Laird, John R.; Saba, Luca; Suri, Jasjit S.

    2016-01-01

    Background Local hemodynamics plays an important role in atherogenesis and the progression of coronary atherosclerosis disease (CAD). The primary biological effect due to blood turbulence is the change in wall shear stress (WSS) on the endothelial cell membrane, while the local oscillatory nature of the blood flow affects the physiological changes in the coronary artery. In coronary arteries, the blood flow Reynolds number ranges from few tens to several hundreds and hence it is generally assumed to be laminar while calculating the WSS calculations. However, the pulsatile blood flow through coronary arteries under stenotic condition could result in transition from laminar to turbulent flow condition. Methods In the present work, the onset of turbulent transition during pulsatile flow through coronary arteries for varying degree of stenosis (i.e., 0%, 30%, 50% and 70%) is quantitatively analyzed by calculating the turbulent parameters distal to the stenosis. Also, the effect of turbulence transition on hemodynamic parameters such as WSS and oscillatory shear index (OSI) for varying degree of stenosis is quantified. The validated transitional shear stress transport (SST) k-ω model used in the present investigation is the best suited Reynolds averaged Navier-Stokes turbulence model to capture the turbulent transition. The arterial wall is assumed to be rigid and the dynamic curvature effect due to myocardial contraction on the blood flow has been neglected. Results Our observations shows that for stenosis 50% and above, the WSSavg, WSSmax and OSI calculated using turbulence model deviates from laminar by more than 10% and the flow disturbances seems to significantly increase only after 70% stenosis. Our model shows reliability and completely validated. Conclusions Blood flow through stenosed coronary arteries seems to be turbulent in nature for area stenosis above 70% and the transition to turbulent flow begins from 50% stenosis. PMID:27280084

  2. Flexible multivariate hemodynamics fMRI data analyses and simulations with PyHRF

    PubMed Central

    Vincent, Thomas; Badillo, Solveig; Risser, Laurent; Chaari, Lotfi; Bakhous, Christine; Forbes, Florence; Ciuciu, Philippe

    2014-01-01

    As part of fMRI data analysis, the pyhrf package provides a set of tools for addressing the two main issues involved in intra-subject fMRI data analysis: (1) the localization of cerebral regions that elicit evoked activity and (2) the estimation of activation dynamics also known as Hemodynamic Response Function (HRF) recovery. To tackle these two problems, pyhrf implements the Joint Detection-Estimation framework (JDE) which recovers parcel-level HRFs and embeds an adaptive spatio-temporal regularization scheme of activation maps. With respect to the sole detection issue (1), the classical voxelwise GLM procedure is also available through nipy, whereas Finite Impulse Response (FIR) and temporally regularized FIR models are concerned with HRF estimation (2) and are specifically implemented in pyhrf. Several parcellation tools are also integrated such as spatial and functional clustering. Parcellations may be used for spatial averaging prior to FIR/RFIR analysis or to specify the spatial support of the HRF estimates in the JDE approach. These analysis procedures can be applied either to volume-based data sets or to data projected onto the cortical surface. For validation purpose, this package is shipped with artificial and real fMRI data sets, which are used in this paper to compare the outcome of the different available approaches. The artificial fMRI data generator is also described to illustrate how to simulate different activation configurations, HRF shapes or nuisance components. To cope with the high computational needs for inference, pyhrf handles distributing computing by exploiting cluster units as well as multi-core machines. Finally, a dedicated viewer is presented, which handles n-dimensional images and provides suitable features to explore whole brain hemodynamics (time series, maps, ROI mask overlay). PMID:24782699

  3. Hemodynamic Performance of Stage-2 Univentricular Reconstruction: Glenn vs. Hemi-Fontan Templates

    PubMed Central

    Pekkan, Kerem; Dasi, Lakshimi P.; de Zélicourt, Diane; Sundareswaran, Kartik S.; Fogel, Mark A.; Kanter, Kirk R.; Yoganathan, Ajit P.

    2010-01-01

    Flow structures, hemodynamics and the hydrodynamic surgical pathway resistances of the final stage functional single ventricle reconstruction, namely the total cavopulmonary connection (TCPC) anatomy, have been investigated extensively. However, the second stage surgical anatomy (i.e., bi-directional Glenn or hemi-Fontan template) has received little attention. We thus initiated a multi-faceted study, involving magnetic resonance imaging (MRI), phase contrast MRI, computational and experimental fluid dynamics methodologies, focused on the second stage of the procedure. Twenty three-dimensional computer and rapid prototype models of 2nd stage TCPC anatomies were created, including idealized parametric geometries (n = 6), patient-specific anatomies (n = 7), and their virtual surgery variant (n = 7). Results in patient-specific and idealized models showed that the Glenn connection template is hemodynamically more efficient with (83% p = 0.08 in patient-specific models and 66% in idealized models) lower power losses compared to hemi-Fontan template, respectively, due to its direct end-to-side anastomosis. Among the several secondary surgical geometrical features, stenosis at the SVC anastomosis or in pulmonary branches was found to be the most critical parameter in increasing the power loss. The pouch size and flare shape were found to be less significant. Compared to the third stage surgery the hydrodynamic resistance of the 2nd stage is considerably lower (both in idealized models and in anatomical models at MRI resting conditions) for both hemi- and Glenn templates. These results can impact the surgical design and planning of the staged TCPC reconstruction. PMID:18987974

  4. Hemodynamic and neurochemical determinates of renal function in chronic heart failure.

    PubMed

    Gilbert, Cameron; Cherney, David Z I; Parker, Andrea B; Mak, Susanna; Floras, John S; Al-Hesayen, Abdul; Parker, John D

    2016-01-15

    Abnormal renal function is common in acute and chronic congestive heart failure (CHF) and is related to the severity of congestion. However, treatment of congestion often leads to worsening renal function. Our objective was to explore basal determinants of renal function and their response to hemodynamic interventions. Thirty-seven patients without CHF and 59 patients with chronic CHF (ejection fraction; 23 ± 8%) underwent right heart catheterization, measurements of glomerular filtration rate (GFR; inulin) and renal plasma flow (RPF; para-aminohippurate), and radiotracer estimates of renal sympathetic activity. A subset (26 without, 36 with CHF) underwent acute pharmacological intervention with dobutamine or nitroprusside. We explored the relationship between baseline and drug-induced hemodynamic changes and changes in renal function. In CHF, there was an inverse relationship among right atrial mean pressure (RAM) pressure, RPF, and GFR. By contrast, mean arterial pressure (MAP), cardiac index (CI), and measures of renal sympathetic activity were not significant predictors. In those with CHF there was also an inverse relationship among the drug-induced changes in RAM as well as pulmonary artery mean pressure and the change in GFR. Changes in MAP and CI did not predict the change in GFR in those with CHF. Baseline values and changes in RAM pressure did not correlate with GFR in those without CHF. In the CHF group there was a positive correlation between RAM pressure and renal sympathetic activity. There was also an inverse relationship among RAM pressure, GFR, and RPF in patients with chronic CHF. The observation that acute reductions in RAM pressure is associated with an increase in GFR in patients with CHF has important clinical implications. PMID:26561645

  5. Sever's Disease

    MedlinePlus

    ... Are Reading Upsetting News Reports? What to Say Vaccines: Which Ones & When? Smart School Lunches Emmy-Nominated Video "Cerebral Palsy: Shannon's Story" 5 Things to Know About Zika & Pregnancy Sever's Disease KidsHealth > ...

  6. BOLD-based Techniques for Quantifying Brain Hemodynamic and Metabolic Properties – Theoretical Models and Experimental Approaches

    PubMed Central

    Yablonskiy, Dmitriy A.; Sukstanskii, Alexander L.; He, Xiang

    2012-01-01

    Quantitative evaluation of brain hemodynamics and metabolism, particularly the relationship between brain function and oxygen utilization, is important for understanding normal human brain operation as well as pathophysiology of neurological disorders. It can also be of great importance for evaluation of hypoxia within tumors of the brain and other organs. A fundamental discovery by Ogawa and co-workers of the BOLD (Blood Oxygenation Level Dependent) contrast opened a possibility to use this effect to study brain hemodynamic and metabolic properties by means of MRI measurements. Such measurements require developing theoretical models connecting MRI signal to brain structure and functioning and designing experimental techniques allowing MR measurements of salient features of theoretical models. In our review we discuss several such theoretical models and experimental methods for quantification brain hemodynamic and metabolic properties. Our review aims mostly at methods for measuring oxygen extraction fraction, OEF, based on measuring blood oxygenation level. Combining measurement of OEF with measurement of CBF allows evaluation of oxygen consumption, CMRO2. We first consider in detail magnetic properties of blood – magnetic susceptibility, MR relaxation and theoretical models of intravascular contribution to MR signal under different experimental conditions. Then, we describe a “through-space” effect – the influence of inhomogeneous magnetic fields, created in the extravascular space by intravascular deoxygenated blood, on the MR signal formation. Further we describe several experimental techniques taking advantage of these theoretical models. Some of these techniques - MR susceptometry, and T2-based quantification of oxygen OEF – utilize intravascular MR signal. Another technique – qBOLD – evaluates OEF by making use of through-space effects. In this review we targeted both scientists just entering the MR field and more experienced MR researchers

  7. Encephalic hemodynamic phases in subarachnoid hemorrhage: how to improve the protective effect in patient prognoses

    PubMed Central

    de Lima Oliveira, Marcelo; de Azevedo, Daniel Silva; de Azevedo, Milena Krajnyk; de Carvalho Nogueira, Ricardo; Teixeira, Manoel Jacobsen; Bor-Seng-Shu, Edson

    2015-01-01

    Subarachnoid hemorrhage is frequently associated with poor prognoses. Three different hemodynamic phases were identified during subarachnoid hemorrhage: oligemia, hyperemia, and vasospasm. Each phase is associated with brain metabolic changes. In this review, we correlated the hemodynamic phases with brain metabolism and potential treatment options in the hopes of improving patient prognoses. PMID:26109948

  8. Bioimpedance Measurement of Segmental Fluid Volumes and Hemodynamics

    NASA Technical Reports Server (NTRS)

    Montgomery, Leslie D.; Wu, Yi-Chang; Ku, Yu-Tsuan E.; Gerth, Wayne A.; DeVincenzi, D. (Technical Monitor)

    2000-01-01

    Bioimpedance has become a useful tool to measure changes in body fluid compartment volumes. An Electrical Impedance Spectroscopic (EIS) system is described that extends the capabilities of conventional fixed frequency impedance plethysmographic (IPG) methods to allow examination of the redistribution of fluids between the intracellular and extracellular compartments of body segments. The combination of EIS and IPG techniques was evaluated in the human calf, thigh, and torso segments of eight healthy men during 90 minutes of six degree head-down tilt (HDT). After 90 minutes HDT the calf and thigh segments significantly (P < 0.05) lost conductive volume (eight and four percent, respectively) while the torso significantly (P < 0.05) gained volume (approximately three percent). Hemodynamic responses calculated from pulsatile IPG data also showed a segmental pattern consistent with vascular fluid loss from the lower extremities and vascular engorgement in the torso. Lumped-parameter equivalent circuit analyses of EIS data for the calf and thigh indicated that the overall volume decreases in these segments arose from reduced extracellular volume that was not completely balanced by increased intracellular volume. The combined use of IPG and EIS techniques enables noninvasive tracking of multi-segment volumetric and hemodynamic responses to environmental and physiological stresses.

  9. The Effect of Hemodynamics on Cerebral Aneurysm Morphology

    NASA Astrophysics Data System (ADS)

    Metcalfe, Ralph; Mantha, Aishwarya; Karmonik, Christof; Strother, Charles

    2004-11-01

    One of the difficulties in applying principles of hemodynamics to the study of blood flow in aneurysms are the drastic variations in possible shape of both the aneurysms and the parent arteries in the region of interest. We have taken data from three para-opthalmic internal carotid artery aneurysms using 3D-digital subtraction angiography (3D-DSA) and performed CFD simulations of steady and unsteady flows through the three different cases using the same pressure gradients and pulsatile flow waveforms (based on the Ku model for flow through the Carotid bifurcation). We have found that the total pressure differential within the aneurysms is consistent with the direction of flow, and that the dynamic pressure gradient within the aneurysm is very small compared with the static pressure variations. Wall shear stresses were highest near regions of sharp arterial curvature, but always remained low inside the aneurysm. These results suggest a more complex role for hemodynamics in aneurysm generation, growth and rupture.

  10. Development of BOLD signal hemodynamic responses in the human brain

    PubMed Central

    Arichi, Tomoki; Fagiolo, Gianlorenzo; Varela, Marta; Melendez-Calderon, Alejandro; Allievi, Alessandro; Merchant, Nazakat; Tusor, Nora; Counsell, Serena J.; Burdet, Etienne; Beckmann, Christian F.; Edwards, A. David

    2012-01-01

    In the rodent brain the hemodynamic response to a brief external stimulus changes significantly during development. Analogous changes in human infants would complicate the determination and use of the hemodynamic response function (HRF) for functional magnetic resonance imaging (fMRI) in developing populations. We aimed to characterize HRF in human infants before and after the normal time of birth using rapid sampling of the Blood Oxygen Level Dependent (BOLD) signal. A somatosensory stimulus and an event related experimental design were used to collect data from 10 healthy adults, 15 sedated infants at term corrected post menstrual age (PMA) (median 41 + 1 weeks), and 10 preterm infants (median PMA 34 + 4 weeks). A positive amplitude HRF waveform was identified across all subject groups, with a systematic maturational trend in terms of decreasing time-to-peak and increasing positive peak amplitude associated with increasing age. Application of the age-appropriate HRF models to fMRI data significantly improved the precision of the fMRI analysis. These findings support the notion of a structured development in the brain's response to stimuli across the last trimester of gestation and beyond. PMID:22776460

  11. Comparison of two stents in modifying cerebral aneurysm hemodynamics.

    PubMed

    Kim, Minsuok; Taulbee, Dale B; Tremmel, Markus; Meng, Hui

    2008-05-01

    There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent and Wallstent) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation. PMID:18264766

  12. Hemodynamic simulations in coronary aneurysms of children with Kawasaki disease

    NASA Astrophysics Data System (ADS)

    Sengupta, Dibyendu; Burns, Jane; Marsden, Alison

    2009-11-01

    Kawasaki disease (KD) is a serious pediatric illness affecting the cardiovascular system. One of the most serious complications of KD, occurring in about 25% of untreated cases, is the formation of large aneurysms in the coronary arteries, which put patients at risk for myocardial infarction. In this project we performed patient specific computational simulations of blood flow in aneurysmal left and right coronary arteries of a KD patient to gain an understanding about their hemodynamics. Models were constructed from CT data using custom software. Typical pulsatile flow waveforms were applied at the model inlets, while resistance and RCR lumped models were applied and compared at the outlets. Simulated pressure waveforms compared well with typical physiologic data. High wall shear stress values are found in the narrow region at the base of the aneurysm and low shear values occur in regions of recirculation. A Lagrangian approach has been adopted to perform particle tracking and compute particle residence time in the recirculation. Our long-term goal will be to develop links between hemodynamics and the risk for thrombus formation in order to assist in clinical decision-making.

  13. A novel periodic boundary condition for computational hemodynamics studies.

    PubMed

    Bahramian, Fereshteh; Mohammadi, Hadi

    2014-07-01

    In computational fluid dynamics models for hemodynamics applications, boundary conditions remain one of the major issues in obtaining accurate fluid flow predictions. For major cardiovascular models, the realistic boundary conditions are not available. In order to address this issue, the whole computational domain needs to be modeled, which is practically impossible. For simulating fully developed turbulent flows using the large eddy simulation and dynamic numerical solution methods, which are very popular in hemodynamics studies, periodic boundary conditions are suitable. This is mainly because the computational domain can be reduced considerably. In this study, a novel periodic boundary condition is proposed, which is based on mass flow condition. The proposed boundary condition is applied on a square duct for the sake of validation. The mass-based condition was shown to obtain the solution in 15% less time. As such, the mass-based condition has two decisive advantages: first, the solution for a given Reynolds number can be obtained in a single simulation because of the direct specification of the mass flow, and second, simulations can be made more quickly. PMID:25015666

  14. Hemodynamic aspects of normal human feto-placental (umbilical) circulation.

    PubMed

    Acharya, Ganesh; Sonesson, Sven-Erik; Flo, Kari; Räsänen, Juha; Odibo, Anthony

    2016-06-01

    Understanding the changes in normal circulatory dynamics that occur during the course of pregnancy is essential for improving our knowledge of pathophysiological mechanisms associated with feto-placental diseases. The umbilical circulation is the lifeline of the fetus, and it is accessible for noninvasive assessment. However, not all hemodynamic parameters can be reliably measured in utero using currently available technology. Experimental animal studies have been crucial in validating major concepts related to feto-placental circulatory physiology, but caution is required in directly translating the findings of such studies into humans due to species differences. Furthermore, it is important to establish normal reference ranges and take into account gestational age associated changes while interpreting the results of clinical investigation. Therefore, it is necessary to critically evaluate, synthesize and summarize the knowledge available from the studies performed on human pregnancies to be able to appropriately apply them in clinical practice. This narrative review is an attempt to present contemporary concepts on hemodynamics of feto-placental circulation based on human studies. PMID:27130575

  15. Impaired cerebrovascular hemodynamics are associated with cerebral white matter damage

    PubMed Central

    Purkayastha, Sushmita; Fadar, Otite; Mehregan, Aujan; Salat, David H; Moscufo, Nicola; Meier, Dominik S; Guttmann, Charles RG; Fisher, Naomi DL; Lipsitz, Lewis A; Sorond, Farzaneh A

    2014-01-01

    White matter hyperintensities (WMH) in elderly individuals with vascular diseases are presumed to be due to ischemic small vessel diseases; however, their etiology is unknown. We examined the cross-sectional relationship between cerebrovascular hemodynamics and white matter structural integrity in elderly individuals with vascular risk factors. White matter hyperintensity volumes, fractional anisotropy (FA), and mean diffusivity (MD) were obtained from MRI in 48 subjects (75±7years). Pulsatility index (PI) and dynamic cerebral autoregulation (dCA) was assessed using transcranial Doppler ultrasound of the middle cerebral artery. Dynamic cerebral autoregulation was calculated from transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations in the low (LF, 0.03 to 0.15 Hz) and high (HF, 0.16 to 0.5 Hz) frequency ranges. Higher PI was associated with greater WMH (P<0.005). Higher phase across all frequency ranges was associated with greater FA and lower MD (P<0.005). Lower gain was associated with higher FA in the LF range (P=0.001). These relationships between phase and FA were significant in the territories limited to the middle cerebral artery as well as across the entire brain. Our results show a strong relationship between impaired cerebrovascular hemodynamics (PI and dCA) and loss of cerebral white matter structural integrity (WMH and DTI metrics) in elderly individuals. PMID:24129749

  16. Coronary Flow Impacts Aortic Leaflet Mechanics and Aortic Sinus Hemodynamics

    PubMed Central

    Moore, Brandon L.; Dasi, Lakshmi Prasad

    2016-01-01

    Mechanical stresses on aortic valve leaflets are well-known mediators for initiating processes leading to calcific aortic valve disease. Given that non-coronary leaflets calcify first, it may be hypothesized that coronary flow originating from the ostia significantly influences aortic leaflet mechanics and sinus hemodynamics. High resolution time-resolved particle image velocimetry (PIV) measurements were conducted to map the spatiotemporal characteristics of aortic sinus blood flow and leaflet motion with and without physiological coronary flow in a well-controlled in vitro setup. The in vitro setup consists of a porcine aortic valve mounted in a physiological aorta sinus chamber with dynamically controlled coronary resistance to emulate physiological coronary flow. Results were analyzed using qualitative streak plots illustrating the spatiotemporal complexity of blood flow patterns, and quantitative velocity vector and shear stress contour plots to show differences in the mechanical environments between the coronary and non-coronary sinuses. It is shown that the presence of coronary flow pulls the classical sinus vorticity deeper into the sinus and increases flow velocity near the leaflet base. This creates a beneficial increase in shear stress and washout near the leaflet that is not seen in the non-coronary sinus. Further, leaflet opens approximately 10% farther into the sinus with coronary flow case indicating superior valve opening area. The presence of coronary flow significantly improves leaflet mechanics and sinus hemodynamics in a manner that would reduce low wall shear stress conditions while improving washout at the base of the leaflet. PMID:25636598

  17. Bicuspid aortic valve hemodynamics: a fluid-structure interaction study

    NASA Astrophysics Data System (ADS)

    Chandra, Santanu; Seaman, Clara; Sucosky, Philippe

    2011-11-01

    The bicuspid aortic valve (BAV) is a congenital defect in which the aortic valve forms with two leaflets instead of three. While calcific aortic valve disease (CAVD) also develops in the normal tricuspid aortic valve (TAV), its progression in the BAV is more rapid. Although studies have suggested a mechano-potential root for the disease, the native BAV hemodynamics remains largely unknown. This study aimed at characterizing BAV hemodynamics and quantifying the degree of wall-shear stress (WSS) abnormality on BAV leaflets. Fluid-structure interaction models validated with particle-image velocimetry were designed to predict the flow and leaflet dynamics in idealized TAV and BAV anatomies. Valvular function was quantified in terms of the effective orifice area. The regional leaflet WSS was characterized in terms of oscillatory shear index, temporal shear magnitude and temporal shear gradient. The predictions indicate the intrinsic degree of stenosis of the BAV anatomy, reveal drastic differences in shear stress magnitude and pulsatility on BAV and TAV leaflets and confirm the side- and site-specificity of the leaflet WSS. Given the ability of abnormal fluid shear stress to trigger valvular inflammation, these results support the existence of a mechano-etiology of CAVD in the BAV.

  18. Nonparametric hemodynamic deconvolution of FMRI using homomorphic filtering.

    PubMed

    Sreenivasan, Karthik Ramakrishnan; Havlicek, Martin; Deshpande, Gopikrishna

    2015-05-01

    Functional magnetic resonance imaging (fMRI) is an indirect measure of neural activity which is modeled as a convolution of the latent neuronal response and the hemodynamic response function (HRF). Since the sources of HRF variability can be nonneural in nature, the measured fMRI signal does not faithfully represent underlying neural activity. Therefore, it is advantageous to deconvolve the HRF from the fMRI signal. However, since both latent neural activity and the voxel-specific HRF is unknown, the deconvolution must be blind. Existing blind deconvolution approaches employ highly parameterized models, and it is unclear whether these models have an over fitting problem. In order to address these issues, we 1) present a nonparametric deconvolution method based on homomorphic filtering to obtain the latent neuronal response from the fMRI signal and, 2) compare our approach to the best performing existing parametric model based on the estimation of the biophysical hemodynamic model using the Cubature Kalman Filter/Smoother. We hypothesized that if the results from nonparametric deconvolution closely resembled that obtained from parametric deconvolution, then the problem of over fitting during estimation in highly parameterized deconvolution models of fMRI could possibly be over stated. Both simulations and experimental results demonstrate support for our hypothesis since the estimated latent neural response from both parametric and nonparametric methods were highly correlated in the visual cortex. Further, simulations showed that both methods were effective in recovering the simulated ground truth of the latent neural response. PMID:25531878

  19. Endovascular Treatment of Thoracic Aortic Dissection: Hemodynamic Shear Stress Study

    NASA Astrophysics Data System (ADS)

    Tang, Yik Sau; Lai, Siu Kai; Cheng, Stephen Wing Keung; Chow, Kwok Wing

    2012-11-01

    Thoracic Aortic Dissection (TAD), a life threatening cardiovascular disease, occurs when blood intrudes into the layers of the aortic wall, creating a new artificial channel (the false lumen) beside the original true lumen. The weakened false lumen wall may expand, enhancing the risk of rupture and resulting in high mortality. Endovascular treatment involves the deployment of a stent graft into the aorta, thus blocking blood from entering the false lumen. Due to the irregular geometry of the aorta, the stent graft, however, may fail to conform to the vessel curvature, and would create a ``bird-beak'' configuration, a wedge-shaped domain between the graft and the vessel wall. Computational fluid dynamics analysis is employed to study the hemodynamics of this pathological condition. With the `beaking' configuration, the local hemodynamic shear stress will drop below the threshold of safety reported earlier in the literature. The oscillating behavior of the shear stress might lead to local inflammation, atherosclerosis and other undesirable consequences. Supported by the Innovation and Technology Fund of the Hong Kong Government.

  20. Renal Hemodynamics in AKI: In Search of New Treatment Targets.

    PubMed

    Matejovic, Martin; Ince, Can; Chawla, Lakhmir S; Blantz, Roland; Molitoris, Bruce A; Rosner, Mitchell H; Okusa, Mark D; Kellum, John A; Ronco, Claudio

    2016-01-01

    Novel therapeutic interventions are required to prevent or treat AKI. To expedite progress in this regard, a consensus conference held by the Acute Dialysis Quality Initiative was convened in April of 2014 to develop recommendations for research priorities and future directions. Here, we highlight the concepts related to renal hemodynamics in AKI that are likely to reveal new treatment targets on investigation. Overall, we must better understand the interactions between systemic, total renal, and glomerular hemodynamics, including the role of tubuloglomerular feedback. Furthermore, the net consequences of therapeutic maneuvers aimed at restoring glomerular filtration need to be examined in relation to the nature, magnitude, and duration of the insult. Additionally, microvascular blood flow heterogeneity in AKI is now recognized as a common occurrence; timely interventions to preserve the renal microcirculatory flow may interrupt the downward spiral of injury toward progressive kidney failure and should, therefore, be investigated. Finally, development of techniques that permit an integrative physiologic approach, including direct visualization of renal microvasculature and measurement of oxygen kinetics and mitochondrial function in intact tissue in all nephron segments, may provide new insights into how the kidney responds to various injurious stimuli and allow evaluation of new therapeutic strategies. PMID:26510884

  1. Comparison of Two Stents in Modifying Cerebral Aneurysm Hemodynamics

    PubMed Central

    Kim, Minsuok; Taulbee, Dale B.; Tremmel, Markus; Meng, Hui

    2009-01-01

    There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent™ and Wallstent®) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation. PMID:18264766

  2. Bayesian hemodynamic parameter estimation by bolus tracking perfusion weighted imaging.

    PubMed

    Boutelier, Timothé; Kudo, Koshuke; Pautot, Fabrice; Sasaki, Makoto

    2012-07-01

    A delay-insensitive probabilistic method for estimating hemodynamic parameters, delays, theoretical residue functions, and concentration time curves by computed tomography (CT) and magnetic resonance (MR) perfusion weighted imaging is presented. Only a mild stationarity hypothesis is made beyond the standard perfusion model. New microvascular parameters with simple hemodynamic interpretation are naturally introduced. Simulations on standard digital phantoms show that the method outperforms the oscillating singular value decomposition (oSVD) method in terms of goodness-of-fit, linearity, statistical and systematic errors on all parameters, especially at low signal-to-noise ratios (SNRs). Delay is always estimated sharply with user-supplied resolution and is purely arterial, by contrast to oSVD time-to-maximum TMAX that is very noisy and biased by mean transit time (MTT), blood volume, and SNR. Residue functions and signals estimates do not suffer overfitting anymore. One CT acute stroke case confirms simulation results and highlights the ability of the method to reliably estimate MTT when SNR is low. Delays look promising for delineating the arterial occlusion territory and collateral circulation. PMID:22410325

  3. Neuronal or Hemodynamic? Grappling with the Functional MRI Signal

    PubMed Central

    2014-01-01

    Abstract Magnetic resonance imaging (MRI) and functional MRI (fMRI) continue to advance because creative physicists, engineers, neuroscientists, clinicians, and physiologists find new ways for extracting more information from the signal. Innovations in pulse sequence design, paradigm design, and processing methods have advanced the field and firmly established fMRI as a cornerstone for understanding the human brain. In this article, the field of fMRI is described through consideration of the central problem of separating hemodynamic from neuronal information. Discussed here are examples of how pulse sequences, activation paradigms, and processing methods are integrated such that novel, high-quality information can be obtained. Examples include the extraction of information such as activation onset latency, metabolic rate, neuronal adaptation, vascular patency, vessel diameter, vigilance, and subvoxel activation. Experimental measures include time series latency, hemodynamic shape, MR phase, multivoxel patterns, ratios of activation-related R2* to R2, metabolic rate changes, fluctuation correlations and frequencies, changes in fluctuation correlations and frequencies over time, resting correlation states, echo time dependence, and more. PMID:25093397

  4. Four-dimensional coronary morphology and computational hemodynamics

    NASA Astrophysics Data System (ADS)

    Wahle, Andreas; Mitchell, Steven C.; Ramaswamy, Sharan D.; Chandran, Krishnan B.; Sonka, Milan

    2001-07-01

    Conventional reconstructions from intravascular ultrasound (IVUS) stack the frames as acquired during the pullback of the catheter to form a straight three-dimensional volume, thus neglecting the vessel curvature and merging images from different heart phases. We are developing a comprehensive system for fusion of the IVUS data with the pullback path as determined from x-ray angiography, to create a geometrically accurate 4-D (3-D plus time) model of the coronary vasculature as basis for computational hemodynamics. The overall goal of our work is to correlate shear stress with plaque thickness. The IVUS data are obtained in a single pullback using an automated pullback device; the frames are afterwards assigned to their respective heart phases based upon the ECG signal. A set of 3-D models is reconstructed by fusion of IVUS and angiographic data corresponding to the same ECG-gated heart phase; methods of computational fluid dynamics (CFD) are applied to obtain important hemodynamic data. Combining these models yields the final 4-D reconstruction. Visualization is performed using the platform-independent VRML standard for a user-friendly manipulation of the scene. An extension for virtual angioscopy allows an easy assessment of the vessel features within their local context. Validation was successfully performed both in-vitro and in-vivo.

  5. Pulmonary Hypertension an Independent Risk Factor for Death in Intensive Care Unit: Correlation of Hemodynamic Factors with Mortality

    PubMed Central

    Saydain, Ghulam; Awan, Aamir; Manickam, Palaniappan; Kleinow, Paul; Badr, Safwan

    2015-01-01

    OBJECTIVE Critically ill patients with pulmonary hypertension (PH) pose additional challenges due to the existence of right ventricular (RV) dysfunction. The purpose of this study was to assess the impact of hemodynamic factors on the outcome. METHODS We reviewed the records of patients with a diagnosis of PH admitted to the intensive care unit. In addition to evaluating traditional hemodynamic parameters, we defined severe PH as right atrial pressure >20 mmHg, mean pulmonary artery pressure >55 mmHg, or cardiac index (CI) <2 L/min/m2. We also defined the RV functional index (RFI) as pulmonary artery systolic pressure (PASP) adjusted for CI as PASP/CI; increasing values reflect RV dysfunction. RESULTS Fifty-three patients (mean age 60 years, 72% women, 79% Blacks), were included in the study. Severe PH was present in 68% of patients who had higher Sequential Organ Failure Assessment (SOFA) score (6.8 ± 3.3 vs 3.8 ± 1.6; P = 0.001) and overall in-hospital mortality (36% vs 6%; P = 0.02) compared to nonsevere patients, although Acute Physiology and Chronic Health Evaluation (APACHE) II scores (19.9 ± 7.5 vs 18.5 ± 6.04; P = 0.52) were similar and sepsis was more frequent among nonsevere PH patients (31 vs 64%; P = 0.02). Severe PH (P = 0.04), lower mean arterial pressure (P = 0.04), and CI (P = 0.01); need for invasive ventilation (P = 0.02) and vasopressors (P = 0.03); and higher SOFA (P = 0.001), APACHE II (P = 0.03), pulmonary vascular resistance index (PVRI) (P = 0.01), and RFI (P = 0.004) were associated with increased mortality. In a multivariate model, SOFA [OR = 1.45, 95% confidence interval (C.I.) = 1.09–1.93; P = 0.01], PVRI (OR = 1.12, 95% C.I. = 1.02–1.24; P = 0.02), and increasing RFI (OR = 1.06, 95% C.I. = 1.01–1.11; P = 0.01) were independently associated with mortality. CONCLUSION PH is an independent risk factor for mortality in critically ill patients. Composite factors rather than individual hemodynamic parameters are better predictors of

  6. Computational Modeling of the Effects of Myocardial Infarction on Left Ventricular Hemodynamics

    NASA Astrophysics Data System (ADS)

    Vedula, Vijay; Seo, Jung Hee; Mittal, Rajat; Fortini, Stefania; Querzoli, Giorgio

    2012-11-01

    Most in-vivo and modeling studies on myocardial infarction and ischemia have been directed towards understanding the left ventricular wall mechanics including stress-strain behavior, end systolic pressure-volume correlations, ejection fraction and stroke work. Fewer studies have focused on the alterations in the intraventricular blood flow behavior due to local infarctions. Changes in the motion of the endocardium can cause local circulation and stagnation regions; these increase the blood cell residence time in the left ventricle and may eventually be implicated in thrombus formation. In the present study, we investigate the effects of myocardial infarction on the ventricular hemodynamics in simple models of the left ventricle using an immersed-boundary flow solver. Apart from the Eulerian flow features such as vorticity and velocity flow fields, pressure distribution, shear stress, viscous dissipation and pump work, we also examine the Lagrangian dynamics of the flow to gain insights into the effect of flow dynamics on thrombus formation. The study is preceded by a comprehensive validation study which is based on an in-vitro experimental model of the left ventricle and this study is also described. This research is supported by the U.S. National Science Foundation through (NSF) CDI-Type II grant IOS-1124804. Computational resources for some of the simulations were also provided in part through the NSF grant NSF-OCI-108849.

  7. Hemodynamics in a Pediatric Ascending Aorta Using a Viscoelastic Pediatric Blood Model.

    PubMed

    Good, Bryan C; Deutsch, Steven; Manning, Keefe B

    2016-04-01

    Congenital heart disease is the leading cause of infant death in the United States with over 36,000 newborns affected each year. Despite this growing problem there are few mechanical circulatory support devices designed specifically for pediatric and neonate patients. Previous research has been done investigating pediatric ventricular assist devices (PVADs) assuming blood to be a Newtonian fluid in computational fluid dynamics (CFD) simulations, ignoring its viscoelastic and shear-thinning properties. In contrast to adult VADs, PVADs may be more susceptible to hemolysis and thrombosis due to altered flow into the aorta, and therefore, a more accurate blood model should be used. A CFD solver that incorporates a modified Oldroyd-B model designed specifically for pediatric blood is used to investigate important hemodynamic parameters in a pediatric aortic model under pulsatile flow conditions. These results are compared to Newtonian blood simulations at three physiological pediatric hematocrits. Minor differences are seen in both velocity and wall shear stress (WSS) during early stages of the cardiac cycle between the Newtonian and viscoelastic models. During diastole, significant differences are seen in the velocities in the descending aorta (up to 12%) and in the aortic branches (up to 30%) between the two models. Additionally, peak WSS differences are seen between the models throughout the cardiac cycle. At the onset of diastole, peak WSS differences of 43% are seen between the Newtonian and viscoelastic model and between the 20 and 60% hematocrit viscoelastic models at peak systole of 41%. PMID:26159560

  8. Renal transplant hemodynamics in children: prospective analysis of colour coded versus pulsed Doppler sonography.

    PubMed

    Vergesslich, K A; Barton, P; Hübsch, P; Mostbeck, G; Kainberger, F; Karnel, F; Steger, H; Balzar, E

    1992-01-01

    In 30 children with renal allografts the diagnostic validity of pulsed Doppler (PD) versus colour coded Doppler (CD) sonography was assessed prospectively. 46 PD examinations were performed calculating the resistive index (RI) in the segmental arteries in comparison to 46 CD scans, where renal blood flow throughout the grey-scale image was displayed. In addition, point-spectral analysis with calculation of the RI was also performed on the CD scans. The time for examination ranged from five to ten minutes for the PD and from three to five minutes for the CD study. Concordant findings for the PD and CD technique were generally obtained (normal blood flow pattern on PD-excellent visualization of renal blood flow on CD, reduced or reversed diastolic flow on PD-poor visualization of renal blood flow on CD). There was close correlation of the RI values obtained by the PD and CD scans. CD sonography facilitated point-spectral analysis in shortening the time for examination. The ability to visualize focal hemodynamic alterations provided a higher diagnostic accuracy in comparison to PD sonography. PMID:1508580

  9. An in vitro evaluation of the impact of eccentric deployment on transcatheter aortic valve hemodynamics.

    PubMed

    Gunning, Paul S; Saikrishnan, Neelakantan; McNamara, Laoise M; Yoganathan, Ajit P

    2014-06-01

    Patients with aortic stenosis present with calcium deposits on the native aortic valve, which can result in non-concentric expansion of Transcatheter Aortic Valve Replacement (TAVR) stents. The objective of this study is to evaluate whether eccentric deployment of TAVRs lead to turbulent blood flow and blood cell damage. Particle Image Velocimetry was used to quantitatively characterize fluid velocity fields, shear stress and turbulent kinetic energy downstream of TAVRs deployed in circular and eccentric orifices representative of deployed TAVRs in vivo. Effective orifice area (EOA) and mean transvalvular pressure gradient (TVG) values did not differ substantially in circular and eccentric deployed valves, with only a minor decrease in EOA observed in the eccentric valve (2.0 cm(2) for circular, 1.9 cm(2) for eccentric). Eccentric deployed TAVR lead to asymmetric systolic jet formation, with increased shear stresses (circular = 97 N/m(2) vs. eccentric = 119 N/m(2)) and regions of turbulence intensity (circular = 180 N/m(2) vs. eccentric = 230 N/m(2)) downstream that was not present in the circular deployed TAVR. The results of this study indicate that eccentric deployment of TAVRs can lead to altered flow characteristics and may potentially increase the hemolytic potential of the valve, which were not captured through hemodynamic evaluation alone. PMID:24719050

  10. Computed Tomography Perfusion Assessment of Radiation Therapy Effects on Spinal Cord Hemodynamics

    SciTech Connect

    Spampinato, Maria Vittoria; Bisdas, Sotirios; Sharma, Anand K.; McDonald, Daniel; Strojan, Primoz; Rumboldt, Zoran

    2010-07-01

    Purpose: We used computed tomography (CT) perfusion to evaluate the acute and late effect of radiation therapy (RT) on spinal cord (SC) hemodynamics in patients without symptoms of myelopathy. We hypothesized that SC perfusion could be acutely altered during RT. Methods and Materials: We analyzed neck CT perfusion studies of 36 head-and-neck cancer patients (N1), 16 of whom had previously undergone RT. In a separate group of 6 patients (N2), CT perfusion studies were obtained before RT, after 40 Gy, and after treatment completion. Results: In the N1 group, SC blood flow (BF), blood volume (BV), mean transit time (MTT), and capillary permeability (CP) maps were not significantly different between RT-treated and RT-naive patients. In the N2 group, BF and CP were significantly increased during treatment compared with the baseline and post-RT studies. Conclusions: Radiation therapy of the head and neck may cause transient perturbations of SC perfusion that seem to reverse after treatment. There are no definite chronic effects of RT on SC perfusion observeable at the typical doses administered during treatment of head and neck malignancies.

  11. Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI.

    PubMed

    Marshall-Goebel, Karina; Ambarki, Khalid; Eklund, Anders; Malm, Jan; Mulder, Edwin; Gerlach, Darius; Bershad, Eric; Rittweger, Jörn

    2016-06-15

    Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (-12°) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0°) and after 4.5 h of HDT at -6°, -12° (with and without 1% CO2), and -18°. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during -12° HDT (P = 0.039). Moreover, the addition of 1% CO2 to -12° HDT caused an increase in total arterial blood flow (P = 0.016) and jugular venous outflow (P < 0.001) compared with -12° HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes. PMID:27013606

  12. Effects of short-term exposure to head-down tilt on cerebral hemodynamics: a prospective evaluation of a spaceflight analog using phase-contrast MRI

    PubMed Central

    Ambarki, Khalid; Eklund, Anders; Malm, Jan; Mulder, Edwin; Gerlach, Darius; Rittweger, Jörn

    2016-01-01

    Alterations in cerebral hemodynamics in microgravity are hypothesized to occur during spaceflight and could be linked to the Visual Impairment and Intracranial Pressure syndrome. Head-down tilt (HDT) is frequently used as a ground-based analog to simulate cephalad fluid shifts in microgravity; however, its effects on cerebral hemodynamics have not been well studied with MRI techniques. Here, we evaluate the effects of 1) various HDT angles on cerebral arterial and venous hemodynamics; and 2) exposure to 1% CO2 during an intermediate HDT angle (−12°) as an additional space-related environmental factor. Blood flow, cross-sectional area (CSA), and blood flow velocity were measured with phase-contrast MRI in the internal jugular veins, as well as the vertebral and internal carotid arteries. Nine healthy male subjects were measured at baseline (supine, 0°) and after 4.5 h of HDT at −6°, −12° (with and without 1% CO2), and −18°. We found a decrease in total arterial blood flow from baseline during all angles of HDT. On the venous side, CSA increased with HDT, and outflow decreased during −12° HDT (P = 0.039). Moreover, the addition of 1% CO2 to −12° HDT caused an increase in total arterial blood flow (P = 0.016) and jugular venous outflow (P < 0.001) compared with −12° HDT with ambient atmosphere. Overall, the results indicate decreased cerebral blood flow during HDT, which may have implications for microgravity-induced cerebral hemodynamic changes. PMID:27013606

  13. Sildenafil Exposure and Hemodynamic Effect after Fontan Surgery

    PubMed Central

    Tunks, Robert D.; Barker, Piers C. A.; Benjamin, Daniel K.; Cohen-Wolkowiez, Michael; Fleming, Gregory A.; Laughon, Matthew; Li, Jennifer S.; Hill, Kevin D.

    2013-01-01

    Objective Determine sildenafil exposure and hemodynamic effect in children after Fontan single-ventricle surgery. Design Prospective, dose-escalation trial. Setting Single-center, pediatric catheterization laboratory. Patients 9 children post Fontan single-ventricle surgical palliation and undergoing elective cardiac catheterization: Median (range) age and weight: 5.2 years (2.5–9.4) and 16.3 kg (9.5–28.1). Five children (55%) were male, and 6/9 (67%) had a systemic right ventricle. Interventions Catheterization and echocardiography performed before and immediately after single-dose intravenous sildenafil (0.25, 0.35, or 0.45 mg/kg over 20 minutes). Measurements Peak sildenafil and des-methyl sildenafil concentration, change in hemodynamic parameters measured by cardiac catheterization and echocardiography. Main Results Maximum sildenafil concentrations ranged from 124–646 ng/ml and were above the in vitro threshold needed for 77% phosphodiesterase type-5 (PDE-5) inhibition in 8/9 children and 90% inhibition in 7/7 of children with doses ≥0.35 mg/kg. Sildenafil improved stroke volume (+22%, p=0.05) and cardiac output (+10%, p=0.01) with no significant change in heart rate in 8/9 children. Sildenafil also lowered systemic (-16%, p=0.01) and pulmonary vascular resistance index (PVRI) in all 9 children (median baseline PVRI 2.4 [range: 1.3, 3.7]; decreased to 1.9 [0.8, 2.7] WU x m2; p=0.01) with no dose-response effect. Pulmonary arterial pressures decreased (−10%, p=0.02) and pulmonary blood flow increased (9%, p=0.02). There was no change in myocardial performance index and no adverse events. Conclusions After Fontan surgery, sildenafil infusion acutely improves cardiopulmonary hemodynamics, increasing cardiac index. For the range of doses studied, exposure was within the acute safety range reported in adult subjects. PMID:24201857

  14. Estimating Hemodynamic Responses to the Wingate Test Using Thoracic Impedance

    PubMed Central

    Astorino, Todd A.; Bovee, Curtis; DeBoe, Ashley

    2015-01-01

    Techniques including direct Fick and Doppler echocardiography are frequently used to assess hemodynamic responses to exercise. Thoracic impedance has been shown to be a noninvasive alternative to these methods for assessing these responses during graded exercise to exhaustion, yet its feasibility during supramaximal bouts of exercise is relatively unknown. We used thoracic impedance to estimate stroke volume (SV) and cardiac output (CO) during the Wingate test (WAnT) and compared these values to those from graded exercise testing (GXT). Active men (n = 9) and women (n = 7) (mean age = 24.8 ± 5.9 yr) completed two Wingate tests and two graded exercise tests on a cycle ergometer. During exercise, heart rate (HR), SV, and CO were continuously estimated using thoracic impedance. Repeated measures analysis of variance was used to identify potential differences in hemodynamic responses across protocols. Results: Maximal SV (138.6 ± 37.4 mL vs. 135.6 ± 26.9 mL) and CO (24.5 ± 6.1 L·min-1 vs. 23.7 ± 5.1 L·min-1) were similar (p > 0.05) between repeated Wingate tests. Mean maximal HR was higher (p < 0.01) for GXT (185 ± 7 b·min-1) versus WAnT (177 ± 11 b·min-1), and mean SV was higher in response to WAnT (137.1 ± 32.1 mL) versus GXT (123.0 ± 32.0 mL), leading to similar maximal cardiac output between WAnT and GXT (23.9 ± 5.6 L·min-1 vs. 22.5 ± 6.0 L·min-1). Our data show no difference in hemodynamic responses in response to repeated administrations of the Wingate test. In addition, the Wingate test elicits similar cardiac output compared to progressive cycling to VO2max. Key points Measurement of cardiac output (CO), the rate of oxygen transport delivered by the heart to skeletal muscle, is not widely-employed in Exercise Physiology due to the level of difficulty and invasiveness characteristic of most techniques used to measure this variable. Nevertheless, thoracic impedance has been shown to provide a noninvasive and simpler approach to continuously

  15. Pros and Cons of Using the Informed Basis Set to Account for Hemodynamic Response Variability with Developmental Data

    PubMed Central

    Cignetti, Fabien; Salvia, Emilie; Anton, Jean-Luc; Grosbras, Marie-Hélène; Assaiante, Christine

    2016-01-01

    Conventional analysis of functional magnetic resonance imaging (fMRI) data using the general linear model (GLM) employs a neural model convolved with a canonical hemodynamic response function (HRF) peaking 5 s after stimulation. Incorporation of a further basis function, namely the canonical HRF temporal derivative, accounts for delays in the hemodynamic response to neural activity. A population that may benefit from this flexible approach is children whose hemodynamic response is not yet mature. Here, we examined the effects of using the set based on the canonical HRF plus its temporal derivative on both first- and second-level GLM analyses, through simulations and using developmental data (an fMRI dataset on proprioceptive mapping in children and adults). Simulations of delayed fMRI first-level data emphasized the benefit of carrying forward to the second-level a derivative boost that combines derivative and nonderivative beta estimates. In the experimental data, second-level analysis using a paired t-test showed increased mean amplitude estimate (i.e., increased group contrast mean) in several brain regions related to proprioceptive processing when using the derivative boost compared to using only the nonderivative term. This was true especially in children. However, carrying forward to the second-level the individual derivative boosts had adverse consequences on random-effects analysis that implemented one-sample t-test, yielding increased between-subject variance, thus affecting group-level statistic. Boosted data also presented a lower level of smoothness that had implication for the detection of group average activation. Imposing soft constraints on the derivative boost by limiting the time-to-peak range of the modeled response within a specified range (i.e., 4–6 s) mitigated these issues. These findings support the notion that there are pros and cons to using the informed basis set with developmental data. PMID:27471441

  16. Effects of Intravenous Magnesium Sulfate and Lidocaine on Hemodynamic Variables Following Direct Laryngoscopy and Intubation in Elective Surgery Patients

    PubMed Central

    Dehkordi, Masih Ebrahimi; Radpay, Badiozaman; Teimoorian, Hooman; Mohajerani, Seyed Amir

    2013-01-01

    Background Laryngoscopy and intubation incur hemodynamic changes like increase in heart rate, arterial blood pressure, pulmonary artery pressure, wedge capillary pressure and arrhythmias. Anesthesiologists are continually in search of ways to alleviate such complications. Several medicinal methods have been suggested that serve the purpose including the administration of intravenous magnesium sulfate to minimize these unfavorable responses. This study compares the effects of intravenous administration of lidocaine and magnesium sulfate on unwanted hemodynamic responses following laryngoscopy and intubation in elective surgery candidates. Materials and Methods This randomized double-blind clinical trial was conducted on 60 ASA-I and ASA-II candidates who received 60 mg/kg (based on Lean Body Mass) magnesium sulfate or lidocaine randomly before intubation. Values of systolic and diastolic blood pressures, mean arterial pressure, and heart rate were recorded for both groups during the 5 minutes following administration, and compared with baseline values. Results In both groups, systolic blood pressure increased compared to the baseline value. However, there was a significant difference between the two groups as this increase occurred within the first 3 minutes in the lidocaine group, while within the first minute in the magnesium sulfate group. The increase in diastolic blood pressure was not significant. But there was a significant difference in the mean arterial pressure increase between the two groups since in the magnesium sulfate group this increase occurred in the first minute whereas in the lidocaine group it occurred during the first two minutes. There was no significant difference in the heart rates after intubation between the two groups. Conclusion Magnesium sulfate is more effective than lidocaine in controlling hemodynamics, although it may increase the heart rate. PMID:25191450

  17. Differences in the hemodynamic response to event-related motor and visual paradigms as measured by near-infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Jasdzewski, G.; Strangman, G.; Wagner, J.; Kwong, K. K.; Poldrack, R. A.; Boas, D. A.; Sutton, J. P. (Principal Investigator)

    2003-01-01

    Several current brain imaging techniques rest on the assumption of a tight coupling between neural activity and hemodynamic response. The nature of this neurovascular coupling, however, is not completely understood. There is some evidence for a decoupling of these processes at the onset of neural activity, which manifests itself as a momentary increase in the relative concentration of deoxyhemoglobin (HbR). The existence of this early component of the hemodynamic response function, however, is controversial, as it is inconsistently found. Near infrared spectroscopy (NIRS) allows quantification of levels of oxyhemoglobin (HbO(2)) and HbR during task performance in humans. We acquired NIRS data during performance of simple motor and visual tasks, using rapid-presentation event-related paradigms. Our results demonstrate that rapid, event-related NIRS can provide robust estimates of the hemodynamic response without artifacts due to low-frequency signal components, unlike data from blocked designs. In both the motor and visual data the onset of the increase in HbO(2) occurs before HbR decreases, and there is a poststimulus undershoot. Our results also show that total blood volume (HbT) drops before HbO(2) and undershoots baseline, raising a new issue for neurovascular models. We did not find early deoxygenation in the motor data using physiologically plausible values for the differential pathlength factor, but did find one in the visual data. We suggest that this difference, which is consistent with functional magnetic resonance imaging (fMRI) data, may be attributable to different capillary transit times in these cortices.

  18. Genes influence the amplitude and timing of brain hemodynamic responses.

    PubMed

    Shan, Zuyao Y; Vinkhuyzen, Anna A E; Thompson, Paul M; McMahon, Katie L; Blokland, Gabriëlla A M; de Zubicaray, Greig I; Calhoun, Vince; Martin, Nicholas G; Visscher, Peter M; Wright, Margaret J; Reutens, David C

    2016-01-01

    In functional magnetic resonance imaging (fMRI), the hemodynamic response function (HRF) reflects regulation of regional cerebral blood flow in response to neuronal activation. The HRF varies significantly between individuals. This study investigated the genetic contribution to individual variation in HRF using fMRI data from 125 monozygotic (MZ) and 149 dizygotic (DZ) twin pairs. The resemblance in amplitude, latency, and duration of the HRF in six regions in the frontal and parietal lobes was compared between MZ and DZ twin pairs. Heritability was estimated using an ACE (Additive genetic, Common environmental, and unique Environmental factors) model. The genetic influence on the temporal profile and amplitude of HRF was moderate to strong (24%-51%). The HRF may be used in the genetic analysis of diseases with a cerebrovascular etiology. PMID:26375212

  19. Lung effect on the hemodynamics in pulmonary artery

    NASA Astrophysics Data System (ADS)

    Tsai, S. F.; Sheu, Tony W. H.; Chang, T. M.

    2001-06-01

    The present study investigates blood flow in a pulmonary artery. The aim is to gain a better understanding of offset value in vascular circulation through a two-dimensional analysis of the Navier-Stokes equations. In this study, the hemodynamics in a blood vessel with truncated outlets at which constant pressure is specified is examined. To simplify the analysis, the vessel walls are regarded as being rigid. In quadratic elements, the streamline upwind Petrov-Galerkin finite element model is employed to simulate the incompressible Newtonian blood flow. The adopted finite element model introduces artificial damping terms solely in the streamline direction. With these terms added to the formulation, the discrete system is enhanced while solution accuracy is maintained without deterioration due to numerical diffusion errors. Copyright

  20. CFD modeling of pulsatile hemodynamics in the total cavopulmonary connection

    NASA Astrophysics Data System (ADS)

    Zobaer, S. M. Tareq; Hasan, A. B. M. Toufique

    2016-07-01

    Total cavopulmonary connection is a blood flow pathway which is created surgically by an operation known as Fontan procedure, performed on children with single ventricle heart defects. Recent studies have shown that the hemodynamics in the connection can be strongly influenced by the presence of pulsatile flow. The aim of this paper is model the pulsatile flow patterns, and to calculate the vorticity field and power losses in an idealized 1.5D offset model of Total Cavopulmonary Connection. A three-dimensional polyhedral mesh was constructed for the numerical simulation. The rheological properties of blood were considered as Newtonian, and flow in the connection was assumed to be laminar. The results demonstrated complex flow patterns in the connection. The outcomes of the simulation showed reasonable agreement with the results available in the literature for a similar model.

  1. Hemodynamic responses to functional activation accessed by optical imaging

    NASA Astrophysics Data System (ADS)

    Ni, Songlin; Li, Pengcheng; Yang, Yuanyuan; Lv, Xiaohua; Luo, Qingming

    2006-01-01

    A multi-wavelength light-emitting diode (LED) and laser diode (LD) based optical imaging system was developed to visualize the changes in cerebral blood flow, oxygenation following functional activation simultaneously in rodent cortex. The 2-D blood flow image was accessed by laser speckle contrast imaging, and the spectroscopic imaging of intrinsic signal was used for the calculation of oxyhemoglobin (HbO), deoxyhemoglobin (Hb) and total hemoglobin (HbT) concentration. The combination of spectroscopic imaging and laser speckle contrast imaging provides the capability to simultaneously investigate the spatial and temporal blood flow and hemoglobin concentration changes with high resolution, which may lead to a better understanding of the coupling between neuronal activation and vascular responses. The optical imaging system been built is compact and convenient to investigators. And it is reliable to acquire raw data. In present study, the hemodynamic responses to cortical spreading depression (CSD) in parietal cortex of ~-chloralose/urethan anesthetized rats were demonstrated.

  2. Echocardiographic Hemodynamic Monitoring in the Critically Ill Patient

    PubMed Central

    Romero-Bermejo, Francisco J; Ruiz-Bailén, Manuel; Guerrero-De-Mier, Manuel; López-Álvaro, Julián

    2011-01-01

    Echocardiography has shown to be an essential diagnostic tool in the critically ill patient's assessment. In this scenario the initial fluid therapy, such as it is recommended in the actual clinical guidelines, not always provides the desired results and maintains a considerable incidence of cardiorrespiratory insufficiency. Echocardiography can council us on these patients' clinical handling, not only the initial fluid therapy but also on the best-suited election of the vasoactive/inotropic treatment and the early detection of complications. It contributes as well to improving the etiological diagnosis, allowing one to know the heart performance with more precision. The objective of this manuscript is to review the more important parameters that can assist the intensivist in theragnosis of hemodynamically unstable patients. PMID:22758613

  3. Hemodynamic response in a geographical word naming verbal fluency test.

    PubMed

    Marino, Julian; Redondo, Santiago; Luna, Fernando G; Sanchez, Luis M; Torres, Gustavo Foa

    2014-01-01

    Functional hemodynamic response was studied in a new Verbal Fluency Task (VFT) that demanded the production of geographical words while fMRI data was obtained. Participants completed 7 trials with a total duration of 2 min. 20 s. Four simple arithmetic subtraction trials were alternated with 3 geographical naming trials. Each trial had a duration of 20 s. Brain activity was contrasted between both conditions and significant differences (p < .05, Family Wise Error correction) were observed in the prefrontal medial gyrus, typically associated with word retrieval and phonological awareness, and in the parahippocampal gyrus, posterior cingulate cortex and lingual gyrus, areas related to spatial cognition. These results indicate that geographic VFT could be incorporated into a browser of cognitive processes using VFT considering its specific relationship with spatial cognition. Further investigations are proposed, taking special interest in the gender variable and eliminating phonological restrictions, because the evoked Argentinean cities and towns ended in a consonant letter. PMID:25012096

  4. Optimal hemodynamic response model for functional near-infrared spectroscopy

    PubMed Central

    Kamran, Muhammad A.; Jeong, Myung Yung; Mannan, Malik M. N.

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650–950 nm wavelengths. The cortical hemodynamic response (HR) differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF) is modeled by two Gamma functions with six unknown parameters (four of them to model the shape and other two to scale and baseline respectively). The HRF model is supposed to be a linear combination of HRF, baseline, and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown). An objective function is developed as a square of the residuals with constraints on 12 free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using 10 real and 15 simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis (i.e., t-value > tcritical and p-value < 0.05). PMID:26136668

  5. Critical Transitions in Early Embryonic Aortic Arch Patterning and Hemodynamics

    PubMed Central

    Kowalski, William J.; Dur, Onur; Wang, Yajuan; Patrick, Michael J.; Tinney, Joseph P.; Keller, Bradley B.; Pekkan, Kerem

    2013-01-01

    Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in the developing embryo, and observed that these two stages contained different aortic arch patterns with no inter-embryo variation. In the present study, we investigate these biomechanical events in the intermediate stage 21 to determine insights into this critical transition. We performed fluorescent dye microinjections to identify aortic arch patterns and measured diameters using both injection recordings and high-resolution optical coherence tomography. Flow and WSS were quantified with 3D computational fluid dynamics (CFD). Dye injections revealed that the transition in aortic arch pattern is not a uniform process and multiple configurations were documented at stage 21. CFD analysis showed that WSS is substantially elevated compared to both the previous (stage 18) and subsequent (stage 24) developmental time-points. These results demonstrate that acute increases in WSS are followed by a period of vascular remodeling to restore normative hemodynamic loading. Fluctuations in blood flow are one possible mechanism that impacts the timing of events such as aortic arch regression and generation, leading to the variable configurations at stage 21. Aortic arch variations noted during normal rapid vascular remodeling at stage 21 identify a

  6. Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

    NASA Astrophysics Data System (ADS)

    Wojciechowski, Dariusz; Sionek, Piotr; Peczalski, Kazimierz; Janusek, Dariusz

    2011-01-01

    The paper presents potential role of plethyzmography in optimization of heart hemodynamic function during pacemaker programming. The assessment of optimal stroke volume in patients, with implanted dual chamber pacemaker (DDD), by plethyzmography was a goal of the study. The data were collected during pacing rhythm. 20 patients (8 female and 12 male, average 77.4+/-4.6 years) with dual chamber pacemaker (DDD) and with pacing rhythm during routine pacemaker control and study tests were incorporated in the study group. Hemodynamic parameters were assessed during modification of atrio-ventricular delay (AVD) for pacing rhythm of 70 bpm and 90 bpm. The time of atrioventricular was programmed with 20 ms steps within range 100-200 ms and data were recorded with two minutes delay between two consecutive measurements. Stroke volume (SV) and cardiac output (CO) were calculated from plethyzmographic signal by using Beatscope software (TNO Holand). Highest SV calculated for given pacing rhythm was named optimal stroke volume (OSV) and consequently highest cardiac output was named maximal cardiac output (MCO). The time of atrio-ventricular delay for OSV was named optimal atrioventricular delay (OAVD). The results have showed: mean values of OAVD for 70 bpm - 152+/-33 ms and for 90 bpm -149+/-35 ms, shortening of the mean OAVD time caused by increase of pacing rate from 70 bpm to 90 bpm what resulted in statistically significant decrease of OSV with not statistically significant increase of MCO. The analysis of consecutive patients revealed three types of response to increase of pacing rhythm: 1. typical-shortening of OAVD, 2. neutral-no change of OAVD and 3.atypical-lengthening of OAVD.

  7. Mathematical simulation of hemodynamical processes and medical technologies

    NASA Astrophysics Data System (ADS)

    Tsitsyura, Nadiya; Novyc'kyy, Victor V.; Lushchyk, Ulyana B.

    2001-06-01

    Vascular pathologies constitute a significant part of human's diseases and their rate tends to increase. Numerous investigations of brain blood flow in a normal condition and in a pathological one has created a new branch of modern medicine -- angioneurology. It combines the information on brain angioarchitecture and on blood supply in a normal condition and in a pathological one. Investigations of a disease's development constitute an important problem of a modern medicine. Cerebrum blood supply is regulated by arterial inflow and venous outflow, but, unfortunately, in the literature available arterial and venous beds are considered separately. This causes an one-sided interpretation of atherosclerotical and discirculatory encefalopathies. As arterial inflow and venous outflow are interrelated, it seems to be expedient to perform a complex estimation of arteriovenous interactions, prove a correlation dependence connection between the beds and find a dependence in a form of mathematical function. The results will be observed clearly in the graphs. There were 139 patients aged from 2 up to 70 examined in the 'Istyna' Scientific Medical Ultrasound Center by means of a Logidop 2 apparatus manufactured by Kranzbuhler, Germany using a technique of cerebral arteries and veins ultrasound location (invented and patented by Ulyana Lushchyk, State Patent of Ukraine N10262 of 19/07/1995). A clinical interpretation of the results obtained was performed. With the help of this technique and ultrasound Dopplerography the blood flow in major head and cervical arteries was investigated. While performing a visual graphic analysis we paid attention to the changes of carotid artery (CA), internal jugular vein (IJV) and supratrochlear artery's (STA) hemodynamical parameters. Generally accepted blood flow parameters: FS -- maximal systolic frequency and FD -- minimal diastolic frequency were measured. The correlation between different combinations of parameters in the vessels mentioned

  8. Effect of Hemoglobin Transfusion Threshold on Cerebral Hemodynamics and Oxygenation.

    PubMed

    Yamal, Jose-Miguel; Rubin, M Laura; Benoit, Julia S; Tilley, Barbara C; Gopinath, Shankar; Hannay, H Julia; Doshi, Pratik; Aisiku, Imoigele P; Robertson, Claudia S

    2015-08-15

    Cerebral dysfunction caused by traumatic brain injury may adversely affect cerebral hemodynamics and oxygenation leading to worse outcomes if oxygen capacity is decreased due to anemia. In a randomized clinical trial of 200 patients comparing transfusion thresholds <7 g/dl versus 10 g/dl, where transfusion of leukoreduced packed red blood cells was used to maintain the assigned hemoglobin threshold, no long-term neurological difference was detected. The current study examines secondary outcome measures of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain tissue oxygenation (PbtO2) in patients enrolled in this randomized clinical trial. We observed a lower hazard for death (hazard ratio [HR]=0.12, 95% confidence interval [CI]=0.02-0.99) during the first 3 days post-injury, and a higher hazard for death after three days (HR=2.55, 95% CI=1.00-6.53) in the 10 g/dl threshold group as compared to the 7 g/dL threshold group. No significant differences were observed for ICP and CPP but MAP was slightly lower in the 7 g/dL group, although the decreased MAP did not result in increased hypotension. Overall brain tissue hypoxia events were not significantly different in the two transfusion threshold groups. When the PbtO2 catheter was placed in normal brain, however, tissue hypoxia occurred in 25% of patients in the 7 g/dL threshold group, compared to 10.2% of patients in the 10 g/dL threshold group (p=0.04). Although we observed a few differences in hemodynamic outcomes between the transfusion threshold groups, none were of major clinical significance and did not affect long-term neurological outcome and mortality. PMID:25566694

  9. Usefulness of hemodynamic sensors for physiologic cardiac pacing in heart failure patients.

    PubMed

    Occhetta, Eraldo; Bortnik, Miriam; Marino, Paolo

    2011-01-01

    The rate adaptive sensors applied to cardiac pacing should respond as promptly as the normal sinus node with an highly specific and sensitive detection of the need of increasing heart rate. Sensors operating alone may not provide optimal heart responsiveness: central venous pH sensing, variations in the oxygen content of mixed venous blood, QT interval, breathing rate and pulmonary minute ventilation monitored by thoracic impedance variations, activity sensors. Using sensors that have different attributes but that work in a complementary manners offers distinct advantages. However, complicated sensors interactions may occur. Hemodynamic sensors detect changes in the hemodynamic performances of the heart, which partially depends on the autonomic nervous system-induced inotropic regulation of myocardial fibers. Specific hemodynamic sensors have been designed to measure different expression of the cardiac contraction strength: Peak Endocardial Acceleration (PEA), Closed Loop Stimulation (CLS) and TransValvular Impedance (TVI), guided by intraventricular impedance variations. Rate-responsive pacing is just one of the potential applications of hemodynamic sensors in implantable pacemakers. Other issues discussed in the paper include: hemodynamic monitoring for the optimal programmation and follow up of patients with cardiac resynchronization therapy; hemodynamic deterioration impact of tachyarrhythmias; hemodynamic upper rate limit control; monitoring and prevention of vasovagal malignant syncopes. PMID:21461359

  10. Correlation between electrical and hemodynamic responses during visual stimulation with graded contrasts.

    PubMed

    Si, Juanning; Zhang, Xin; Li, Yuejun; Zhang, Yujin; Zuo, Nianming; Jiang, Tianzi

    2016-09-01

    Brain functional activity involves complex cellular, metabolic, and vascular chain reactions, making it difficult to comprehend. Electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) have been combined into a multimodal neuroimaging method that captures both electrophysiological and hemodynamic information to explore the spatiotemporal characteristics of brain activity. Because of the significance of visually evoked functional activity in clinical applications, numerous studies have explored the amplitude of the visual evoked potential (VEP) to clarify its relationship with the hemodynamic response. However, relatively few studies have investigated the influence of latency, which has been frequently used to diagnose visual diseases, on the hemodynamic response. Moreover, because the latency and the amplitude of VEPs have different roles in coding visual information, investigating the relationship between latency and the hemodynamic response should be helpful. In this study, checkerboard reversal tasks with graded contrasts were used to evoke visual functional activity. Both EEG and fNIRS were employed to investigate the relationship between neuronal electrophysiological activities and the hemodynamic responses. The VEP amplitudes were linearly correlated with the hemodynamic response, but the VEP latency showed a negative linear correlation with the hemodynamic response. PMID:27494269

  11. Corrected near infrared spectroscopy, C-NIRS: An optical system for extracting hemodynamic signatures unique to the brain

    NASA Astrophysics Data System (ADS)

    Saager, Rolf B.

    We propose a method, dubbed Corrected Near Infrared Spectroscopy (C-NIRS), to isolate absorption trends confined to the lower layer of a two-layer turbid medium, as is desired in near-infrared spectroscopy (NIRS) of cerebral hemodynamics. The theory behind the operation of this method has been developed and discussed. Several two-layer Monte-Carlo simulations of NIRS time series were generated using a physiologically relevant range of optical properties. Initial results show that by measuring absorption trends at two source-detector separations and performing a least-squares fit of one to the other, processed signals strongly resemble the simulated absorption properties unique to the bottom-layer. Through this approach, it has been demonstrated that fitting coefficients can be estimated without any a priori knowledge of the optical properties present in the model. An analytical approximation for the least squares coefficient provides physical insight into the nature of errors and suggests ways to reduce them. Next, a multi-detector, continuous wave, near infrared spectroscopy system has been developed to examine whether the hemodynamics of the scalp and brain in adults contain significant layer-like hemodynamic trends. NIRS measurements were made using contrasting geometries, one with four detectors equidistant from a source 33 mm away, and one with detectors collinear with the source (5-33 mm away). When NIRS time series were acquired over the prefrontal cortex from resting adults using both geometries, variations among the time series were consistent with a substantially homogeneous two-layer model ( p < 0.001) and inconsistent with one dominated by heterogeneities. Additionally, when time series measured 5 mm from the source were subtracted from corresponding 33 mm signals via a least-squares algorithm, 60% of the hemoglobin changes were on average removed. These results suggest that hemodynamic trends present in the scalp can contribute significantly to NIRS

  12. Intersystem relationships of respiration and hemodynamics in the initial period of postural effects.

    PubMed

    Donina, Zh A; Lavrova, I N; Baranov, V M

    2013-07-01

    We studied the dependence of parameters of lung volumes and the elastic properties of the lungs on changes in the central hemodynamics occurring in the initial period of passive postural changes in cats. It was found that transition from the horizontal to head-up and head-down tilting was accompanied by opposite hemodynamic changes in the cranial and caudal parts of the body. Changes in lung compliance and functional residual capacity of the lungs were opposite and linearly depended on the intensity of hemodynamic shifts, which indicates passive character of the primary disorders primarily determined by a physical factor, gravity-dependent redistribution of body fluids. PMID:24137587

  13. Hemodynamic analysis of patients in intensive care unit based on diffuse optical spectroscopic imaging system

    NASA Astrophysics Data System (ADS)

    Hsieh, Yao-Sheng; Wang, Chun-Yang; Ling, Yo-Wei; Chuang, Ming-Lung; Chuang, Ching-Cheng; Tsai, Jui-che; Lu, Chih-Wei; Sun, Chia-Wei

    2010-02-01

    Diffuse optical spectroscopic imaging (DOSI) is a technique to assess the spatial variation in absorption and scattering properties of the biological tissues and provides the monitoring of changes in concentrations of oxy-hemoglobin and deoxy-hemoglobin. In our preliminary study, the temporal tracings of hemodynamic oxygenation are measured with DOSI and venous occlusion test (VOT) from normal subjects, patients with heart failure and patients with sepsis in intensive care unit (ICU). In experiments, the obvious differences of hemodynamic signals can be observed among the three groups. The physiological relevance of VOT hemodynamics with respect to diseases is also discussed in this paper.

  14. Endovascular management of renal transplant dysfunction secondary to hemodynamic effects related to ipsilateral femoral arteriovenous graft.

    PubMed

    Salsamendi, Jason; Pereira, Keith; Quintana, David; Bleicher, Drew; Tabbara, Marwan; Goldstein, Michael; Narayanan, Govindarajan

    2016-01-01

    Hemodialysis access options become complex in long-term treatment for patients with renal disease, while awaiting renal transplantation (RT). Once upper extremity sites are exhausted, lower extremities are used. RT is preferably in the contralateral iliac fossa, rarely ipsilateral. In current literature, RT dysfunction secondary to the hemodynamic effects of an ipsilateral femoral arteriovenous graft (AVG) has been rarely described. To our knowledge, AVG ligation is the only published technique for hemodynamic correction of an ipsilateral AVG. We present a simple, potentially reversible endovascular approach to manage the hemodynamic effects of an AVG, without potentially permanently losing future AVG access. PMID:26899147

  15. [Peculiarities of hemodynamics in junior students with a hereditary history of arterial hypertension during examination stresses].

    PubMed

    Pershina, T A; Spitsin, A P

    2013-01-01

    The functional state ofthe students was investigated on the basis ofchanges in central hemodynamic indices immediately during exams, in dependence on family history of hypertension. The significant variation in the character of the response of systemic hemodynamics, as depending on the stage of examination (preparation, answering the ticket, and after the exam), the dominance of the type of the autonomic nervous system, and the family history of hypertension has been revealed These changes in hemodynamics in students with family history of hypertension were established to be more pronounced and prolonged. PMID:24340589

  16. Emerging Techniques for Evaluation of the Hemodynamics of Intracranial Vascular Pathology

    PubMed Central

    Huang, Melissa; Chien, Aichi

    2015-01-01

    Advances in imaging modalities have improved the assessment of intracranial hemodynamics using non-invasive techniques. This review examines new imaging modalities and clinical applications of currently available techniques, describes pathophysiology and future directions in hemodynamic analysis of intracranial stenoses, aneurysms and arteriovenous malformations and explores how hemodynamic analysis may have prognostic value in predicting clinical outcomes and assist in risk stratification. The advent of new technologies such as pseudo-continuous arterial spin labeling, accelerated magnetic resonance angiography (MRA) techniques, 4D digital subtraction angiography, and improvements in clinically available techniques such as phase-contrast MRA may change the landscape of vascular imaging and modify current clinical practice guidelines. PMID:25924168

  17. Effects of dipyridamole and aminophylline on hemodynamics, regional myocardial blood flow and thallium-201 washout in the setting of a critical coronary stenosis

    SciTech Connect

    Granato, J.E.; Watson, D.D.; Belardinelli, L.; Cannon, J.M.; Beller, G.A. )

    1990-12-01

    Experiments were performed to characterize the interaction of intravenous dipyridamole and aminophylline on thallium-201 transport kinetics, regional myocardial blood flow and systemic hemodynamics in the presence of a critical coronary artery stenosis. In 12 dogs with a critical left anterior descending coronary artery stenosis, arterial pressure decreased from a mean value (+/- SEM) of 107 +/- 6 to 94 +/- 3 mm Hg and distal left anterior descending artery pressure decreased from 70 +/- 7 to 55 +/- 4 mm Hg after intravenous administration of dipyridamole. In the left anterior descending perfusion zone, the endocardial/epicardial flow ratio decreased from 0.70 to 0.36 and the intrinsic thallium washout rate was significantly prolonged. Intravenous aminophylline reversed the dipyridamole-induced systemic hypotension and transmural coronary steal and restored the thallium washout rate to baseline values. In six other dogs, aminophylline alone resulted in no alterations in systemic and coronary hemodynamics or regional myocardial blood flow. As expected, dipyridamole-induced vasodilation and coronary steal were prevented by aminophylline pretreatment. These data show that in a canine model of partial coronary stenosis, systemic hypotension, adverse regional flow effects and prolonged thallium-201 washout consequent to intravenously administered dipyridamole are promptly reversed by intravenous aminophylline administration. Aminophylline alone had no significant hemodynamic and coronary flow effects. This study provides further insight into the altered thallium kinetics occurring as a consequence of dipyridamole-induced vasodilation and suggests that the prompt reversal of symptoms and signs of ischemia with aminophylline in patients receiving intravenous dipyridamole for clinical imaging studies probably reflects the reversal of transmural coronary steal.

  18. [Severe asthma].

    PubMed

    González, Claudio D

    2016-01-01

    The objectives of this work were to investigate the frequency of severe asthma (SA) according to WHO definition and to compare SA patients' characteristics with those of non-severe asthma (NSA); secondly, to investigate the level of control reached throughout a period of regular treatment. Between 1-1-2005 and 12-31-2014, 471 medical records from patients with bronchial asthma assisted in Buenos Aires City were analyzed. SA frequency was 40.1% (189/471), being significantly higher among patients from the public health system (47.7%, 108/226 vs. 33%, 81/245, p = 0.001). SA patients were older than NSA ones (51.3 ± 17.4 vs. 42.6 ± 17.1 years, p = 0.000), presented longer time since onset of the disease (median 30 vs. 20 years, p = 0.000), lower educational levels (secondary level or higher 41.7% vs. 58.1%, p = 0.000), lower frequency of rhinitis (47% vs. 60.6%, p = 0.004), more severe levels of airway obstruction (FEV% 50.2 ± 13.7 vs. 77.7 ± 12.4, p = 0.000), more frequent antecedents of Near Fatal Asthma (11.1% vs. 2.8%, p = 0.000), higher levels of serum IgE (median of 410 vs. 279 UI/l, p = 0.01) and higher demand of systemic steroids requirements and hospitalizations (68.7% vs. 50.7%, p = 0.000 and 37.5% vs. 15.9%, p = 0.000, respectively). A 30.6% of SA patients (58/189) reached a follow-up period of 12 months, 13 (22.5%) of whom reached the controlled asthma level. The frequency of SA found seems to be considerable. Multicenter studies to investigate the levels of control reached by SA patients with access to proper treatment are recommended. PMID:26826988

  19. Validation of a novel hemodynamic model for coherent hemodynamics spectroscopy (CHS) and functional brain studies with fNIRS and fMRI

    PubMed Central

    Pierro, Michele L.; Hallacoglu, Bertan; Sassaroli, Angelo; Kainerstorfer, Jana M.; Fantini, Sergio

    2013-01-01

    We report an experimental validation and applications of the new hemodynamic model presented in the companion article (Fantini, 2013, this issue) both in the frequency domain and in the time domain. In the frequency domain, we have performed diffuse optical measurements for coherent hemodynamics spectroscopy (CHS) on the brain and calf muscle of human subjects, showing that the hemodynamic model predictions (both in terms of spectral shapes and absolute spectral values) are confirmed experimentally. We show how the quantitative analysis based on the new model allows for autoregulation measurements from brain data, and provides an analytical description of near-infrared spiroximetry from muscle data. In the time domain, we have used data from the literature to perform a comparison between brain activation signals measured with functional near-infrared spectroscopy (fNIRS) or with blood oxygenation level dependent (BOLD) fMRI, and the corresponding signals predicted by the new model. This comparison shows an excellent agreement between the model predictions and the reported fNIRS and BOLD fMRI signals. This new hemodynamic model provides a valuable tool for brain studies with hemodynamic-based techniques. PMID:23562703

  20. Double dissociation between perspective-taking and empathic-concern as predictors of hemodynamic response to another's mistakes.

    PubMed

    Shane, Matthew S; Stevens, Michael C; Harenski, Carla L; Kiehl, Kent A

    2009-06-01

    Identifying another's mistakes requires a basic representation of other's action patterns as well as recognition and understanding of their failed goal-attainment. In previous work, we identified several regions, including inferior parietal cortex and rostral/ventral anterior cinguli (r/vACC), that show unique sensitivity to the observation of another's errors. Here we utilize the same sample to show that participants' level of self-reported perspective-taking (but not empathic concern) correlated with hemodynamic response in IPC, while participants' level of self-reported empathic concern (but not perspective taking) correlated with hemodynamic response in r/vACC. This functional dissociation provides strong evidence for separate roles for IPC and r/vACC in the processing of observed errors. IPC may foster a sense of agency by distinguishing self- from other-performed actions; r/vACC may, in turn, promote a more contextually-mediated understanding of the other's failed goal-attainment. PMID:19244454

  1. Short-term hemodynamic performance of the mitral Carpentier-Edwards PERIMOUNT pericardial valve. Carpentier-Edwards PERIMOUNT Investigators

    NASA Technical Reports Server (NTRS)

    Firstenberg, M. S.; Morehead, A. J.; Thomas, J. D.; Smedira, N. G.; Cosgrove, D. M. 3rd; Marchand, M. A.

    2001-01-01

    BACKGROUND: Although long-term durability data exist, little data are available concerning the hemodynamic performance of the Carpentier-Edwards PERIMOUNT pericardial valve in the mitral position. METHODS: Sixty-nine patients who were implanted with mitral PERIMOUNT valves at seven international centers between January 1996 and February 1997 consented to participate in a short-term echocardiography follow-up. Echocardiographs were collected at a mean of 600+/-133 days after implantation (range, 110 to 889 days); all underwent blinded core lab analysis. RESULTS: At follow-up, peak gradients were 9.09+/-3.43 mm Hg (mean, 4.36+/-1.79 mm Hg) and varied inversely with valve size (p < 0.05). The effective orifice areas were 2.5+/-0.6 cm2 and tended to increase with valve size (p = 0.08). Trace mitral regurgitation (MR) was common (n = 48), 9 patients had mild MR, 1 had moderate MR, none had severe MR. All MR was central (n = 55) or indeterminate (n = 3). No paravalvular leaks were observed. Mitral regurgitation flow areas were 3.4+/-2.8 cm2 and were without significant volumes. CONCLUSIONS: In this multicenter study, these mitral valves are associated with trace, although physiologically insignificant, central MR. Despite known echocardiographic limitations, the PERIMOUNT mitral valves exhibit similar hemodynamics to other prosthetic valves.

  2. Cerebral versus systemic hemodynamics during graded orthostatic stress in humans

    NASA Technical Reports Server (NTRS)

    Levine, B. D.; Giller, C. A.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.

    1994-01-01

    BACKGROUND: Orthostatic syncope is usually attributed to cerebral hypoperfusion secondary to systemic hemodynamic collapse. Recent research in patients with neurocardiogenic syncope has suggested that cerebral vasoconstriction may occur during orthostatic hypotension, compromising cerebral autoregulation and possibly contributing to the loss of consciousness. However, the regulation of cerebral blood flow (CBF) in such patients may be quite different from that of healthy individuals, particularly when assessed during the rapidly changing hemodynamic conditions associated with neurocardiogenic syncope. To be able to interpret the pathophysiological significance of these observations, a clear understanding of the normal responses of the cerebral circulation to orthostatic stress must be obtained, particularly in the context of the known changes in systemic and regional distributions of blood flow and vascular resistance during orthostasis. Therefore, the specific aim of this study was to examine the changes that occur in the cerebral circulation during graded reductions in central blood volume in the absence of systemic hypotension in healthy humans. We hypothesized that cerebral vasoconstriction would occur and CBF would decrease due to activation of the sympathetic nervous system. We further hypothesized, however, that the magnitude of this change would be small compared with changes in systemic or skeletal muscle vascular resistance in healthy subjects with intact autoregulation and would be unlikely to cause syncope without concomitant hypotension. METHODS AND RESULTS: To test this hypothesis, we studied 13 healthy men (age, 27 +/- 7 years) during progressive lower body negative pressure (LBNP). We measured systemic flow (Qc is cardiac output; C2H2 rebreathing), regional forearm flow (FBF; venous occlusion plethysmography), and blood pressure (BP; Finapres) and calculated systemic (SVR) and forearm (FVR) vascular resistances. Changes in brain blood flow were

  3. Anesthetic management of a patient with Marfan syndrome and severe aortic root dilatation undergoing cholecystectomy and partial hepatic resection.

    PubMed

    Ghatak, Tanmoy; Samanta, Sukhen; Samanta, Sujoy

    2013-10-01

    Due to high mortality associated with aortic dissection, anesthetic management of patients with Marfan syndrome with severe aortic root dilation is a challenging situation. We describe the anesthetic management of a patient with Marfan syndrome with severe aortic root dilation, who required major surgery like cholecystectomy with partial liver resection under general anesthesia. A 47-year-old female presented to pre-anesthetic clinic for cholecystectomy with partial hepatic resection for gall bladder carcinoma. Clinical features, transthoracic echocardiography and computed tomography of thorax supported a diagnosis of Marfan syndrome with severely dilated aortic root. Aortic dissection in patients with Marfan syndrome and severely dilated aortic root can be precipitated by major hemodynamic changes under anesthesia. Careful hemodynamic monitoring and avoidance of hemodynamic swings can prevent this life-threatening event. PMID:24348301

  4. Large pulmonary embolus without systemic hemodynamic consequences during cemented hip arthroplasty.

    PubMed

    Oxorn, D; Edelist, G

    1998-05-01

    A case is presented in which a large embolus was detected passing through the right side of the heart during total hip arthroplasty. Although tricuspid regurgitation and an elevated right ventricular pressure resulted, there was no perturbation in systemic hemodynamics or gas exchange. The emboli detected during total hip arthroplasty are most likely composed of fat. No specific treatment is required, although heightened vigilance for disturbances in systemic hemodynamics is important. PMID:9603596

  5. Longitudinal assessment of hemodynamic endpoints in predicting arteriovenous fistula maturation.

    PubMed

    Rajabi-Jagahrgh, Ehsan; Krishnamoorthy, Mahesh K; Roy-Chaudhury, Prabir; Succop, Paul; Wang, Yang; Choe, Ann; Banerjee, Rupak K

    2013-01-01

    Arteriovenous fistula (AVF) nonmaturation is currently a significant clinical problem; however, the mechanisms responsible for this have remained unanswered. Previous work by our group and others has suggested that anatomical configuration and the corresponding hemodynamic endpoints could have an important role in AVF remodeling. Thus, our goal was to assess the longitudinal (temporal) effect of wall shear stress (WSS) on remodeling process of AVFs with two different configurations. The hypothesis is that early assessment of hemodynamic endpoints such as temporal gradient of WSS will predict the maturation status of AVF at later time points. Two AVFs with curved (C-AVF) and straight (S-AVF) configurations were created between the femoral artery and vein of each pig. Three pigs were considered in this study and in total six AVFs (three C-AVF and three S-AVF) were created. The CT scan and ultrasound were utilized to numerically evaluate local WSS at 20 cross-sections along the venous segment of AVFs at 2D (D: days), 7D, and 28D postsurgery. These cross-sections were located at 1.5 mm increments from the anastomosis junction. Local WSS values at these cross-sections were correlated with their corresponding luminal area over time. The WSS in C-AVF decreased from 22.3 ± 4.8 dyn/cm(2) at 2D to 4.1 ± 5.1 dyn/cm(2) at 28D, while WSS increased in S-AVF from 13.0 ± 5.0 dyn/cm(2) at 2D to 36.7 ± 5.3 dyn/cm(2) at 28D. Corresponding to these changes in WSS levels, luminal area of C-AVF dilated (0.23 ± 0.14 cm(2) at 2D to 0.87 ± 0.14 cm(2) at 28D) with attendant increase in flow rate. However, S-AVF had minimal changes in area (0.26 ± 0.02 cm(2) at 2D to 0.27 ± 0.03 cm(2) at 28D) despite some increase in flow rate. Our results suggest that the temporal changes of WSS could have significant effects on AVF maturation. Reduction in WSS over time (regardless of initial values) may result in dilation (p < 0.05), while increase in WSS may be detrimental to maturation. Thus

  6. Acute ethanol intoxication and the trauma patient: hemodynamic pitfalls.

    PubMed

    Bilello, John; McCray, Victor; Davis, James; Jackson, Lascienya; Danos, Leigh Ann

    2011-09-01

    Many trauma patients are acutely intoxicated with alcohol. Animal studies have demonstrated that acute alcohol intoxication inhibits the normal release of epinephrine, norepinephrine, and vasopressin in response to acute hemorrhage. Ethanol also increases nitric oxide release and inhibits antidiuretic hormone secretion. This article studies the effects of alcohol intoxication (measured by blood alcohol level, BAL) on the presentation and resuscitation of trauma patients with blunt hepatic injuries. A retrospective registry and chart review was conducted of all patients who presented with blunt liver injuries at an ACS-verified, level I trauma center. Data collected included admission BAL, systolic blood pressure, hematocrit, International Normalized Ratio (INR), liver injury grade, Injury Severity Score (ISS), intravenous fluid and blood product requirements, base deficit, and mortality. From September 2002 to May 2008, 723 patients were admitted with blunt hepatic injuries. Admission BAL was obtained in 569 patients, with 149 having levels >0.08%. Intoxicated patients were more likely to be hypotensive on admission (p = 0.01) despite a lower liver injury grade and no significant difference in ISS. There was no significant difference in the percent of intoxicated patients requiring blood transfusion. However, when blood was given, intoxicated patients required significantly more units of packed red blood cells (PRBC) than their nonintoxicated counterparts (p = 0.01). Intoxicated patients also required more intravenous fluid during their resuscitation (p = 0.002). Alcohol intoxication may impair the ability of blunt trauma patients to compensate for acute blood loss, making them more likely to be hypotensive on admission and increasing their PRBC and intravenous fluid requirements. All trauma patients should have BAL drawn upon admission and their resuscitation should be performed with an understanding of the physiologic alterations associated with acute alcohol

  7. The acute effect of maximal exercise on central and peripheral arterial stiffness indices and hemodynamics in children and adults.

    PubMed

    Melo, Xavier; Fernhall, Bo; Santos, Diana A; Pinto, Rita; Pimenta, Nuno M; Sardinha, Luís B; Santa-Clara, Helena

    2016-03-01

    This study compared the effects of a bout of maximal running exercise on arterial stiffness in children and adults. Right carotid blood pressure and artery stiffness indices measured by pulse wave velocity (PWV), compliance and distensibility coefficients, stiffness index α and β (echo-tracking), contralateral carotid blood pressure, and upper and lower limb and central/aortic PWV (applanation tonometry) were taken at rest and 10 min after a bout of maximal treadmill running in 34 children (7.38 ± 0.38 years) and 45 young adults (25.22 ± 0.91 years) having similar aerobic potential. Two-by-two repeated measures analysis of variance and analysis of covariance were used to detect differences with exercise between groups. Carotid pulse pressure (PP; η(2) = 0.394) increased more in adults after exercise (p < 0.05). Compliance (η(2) = 0.385) decreased in particular in adults and in those with high changes in distending pressure, similarly to stiffness index α and β. Carotid PWV increased more in adults and was related to local changes in PP but not mean arterial pressure (MAP). Stiffness in the lower limbs decreased (η(2) = 0.115) but apparently only in those with small MAP changes (η(2) = 0.111). No significant exercise or group interaction effects were found when variables were adjusted to height. An acute bout of maximal exercise can alter arterial stiffness and hemodynamics in the carotid artery and within the active muscle beds. Arterial stiffness and hemodynamic response to metabolic demands during exercise in children simply reflect their smaller body size and may not indicate a particular physiological difference compared with adults. PMID:26842667

  8. Increased cortical cell loss and prolonged hemodynamic depression after traumatic brain injury in mice lacking the IP receptor for prostacyclin.

    PubMed

    Lundblad, Cornelia; Grände, Per-Olof; Bentzer, Peter

    2008-02-01

    Prostacyclin is the major arachidonic acid metabolite of the vascular endothelium and is produced mainly via the cyclooxygenase-2 pathway. By acting on the prostacyclin (IP) receptor on platelets and vascular smooth muscle cells, prostacyclin exerts vasodilatory and antiaggregative/antiadhesive effects. Previous studies have shown that prostacyclin production increases after brain trauma, but the importance of prostacyclin for posttraumatic hemodynamic alterations and neuron survival has not been investigated. This study evaluated if endogenous prostacyclin plays a role in the pathophysiologic process in the brain after brain trauma. This was performed by comparing prostacyclin (IP) receptor-deficient (IP(-/-)) mice and mice with functional IP receptor (IP(+/+)) after a controlled cortical injury regarding contusion volume, cerebral blood flow ([(14)C]iodoantipyrine autoradiography), number of perfused capillaries (fluorescein isothiocyanate-dextran fluorescence technique), the transfer constant (K(i)) for [(51)Cr]EDTA, and brain water content (wet vs dry weight) in the injured and contralateral cortex. Contusion volume was increased in IP(-/-) mice compared with IP(+/+) mice. Three hours after trauma, cortical blood flow was decreased in the injured cortex of both groups and the reduction in blood flow in the cortex of the IP(-/-) mice persisted from 3 to 24 h, whereas blood flow approached normal values in the IP(+/+) mice after 24 h. No differences could be detected between the two genotypes regarding other hemodynamic parameters. We conclude that the prostacyclin IP receptor is beneficial for neuron survival after brain trauma in mice, an effect that may be mediated by improved cortical perfusion. PMID:17713464

  9. Role of Mas receptor antagonist (A779) in renal hemodynamics in condition of blocked angiotensin II receptors in rats.

    PubMed

    Mansoori, A; Oryan, S; Nematbakhsh, M

    2016-03-01

    The vasodilatory effect of angiotensin 1-7 (Ang 1-7) is exerted in the vascular bed via Mas receptor (MasR) gender dependently. However, the crosstalk between MasR and angiotensin II (Ang II) types 1 and 2 receptors (AT1R and AT2R) may change some actions of Ang 1-7 in renal circulation. In this study by blocking AT1R and AT2R, the role of MasR in kidney hemodynamics was described. In anaesthetized male and female Wistar rats, the effects of saline as vehicle and MasR blockade (A779) were tested on mean arterial pressure (MAP), renal perfusion pressure (RPP), renal blood flow (RBF), and renal vascular resistance (RVR) when both AT1R and AT2R were blocked by losartan and PD123319, respectively. In male rats, when AT1R and AT2R were blocked, there was a tendency for the increase in RBF/wet kidney tissue weight (RBF/KW) to be elevated by A779 as compared with the vehicle (P=0.08), and this was not the case in female rats. The impact of MasR on renal hemodynamics appears not to be sexual dimorphism either when Ang II receptors were blocked. It seems that co-blockade of all AT1R, AT2R, and MasR may alter RBF/ KW in male more than in female rats. These findings support a crosstalk between MasR and Ang II receptors in renal circulation. PMID:27030624

  10. Physiological and pathological left ventricular hypertrophy of comparable degree is associated with characteristic differences of in vivo hemodynamics.

    PubMed

    Oláh, Attila; Németh, Balázs Tamás; Mátyás, Csaba; Hidi, László; Lux, Árpád; Ruppert, Mihály; Kellermayer, Dalma; Sayour, Alex Ali; Szabó, Lilla; Török, Marianna; Meltzer, Anna; Gellér, László; Merkely, Béla; Radovits, Tamás

    2016-03-01

    Left ventricular (LV) hypertrophy is a physiological or pathological response of LV myocardium to increased cardiac load. We aimed at investigating and comparing hemodynamic alterations in well-established rat models of physiological hypertrophy (PhyH) and pathological hypertrophy (PaH) by using LV pressure-volume (P-V) analysis. PhyH and PaH were induced in rats by swim training and by abdominal aortic banding, respectively. Morphology of the heart was investigated by echocardiography. Characterization of cardiac function was completed by LV P-V analysis. In addition, histological and molecular biological measurements were performed. Echocardiography revealed myocardial hypertrophy of similar degree in both models, which was confirmed by post-mortem heart weight data. In aortic-banded rats we detected subendocardial fibrosis. Reactivation of fetal gene program could be observed only in the PaH model. PhyH was associated with increased stroke volume, whereas unaltered stroke volume was detected in PaH along with markedly elevated end-systolic pressure values. Sensitive indexes of LV contractility were increased in both models, in parallel with the degree of hypertrophy. Active relaxation was ameliorated in athlete's heart, whereas it showed marked impairment in PaH. Mechanical efficiency and ventriculo-arterial coupling were improved in PhyH, whereas they remained unchanged in PaH. Myocardial gene expression of mitochondrial regulators showed marked differences between PaH and PhyH. We provided the first comparative hemodynamic characterization of PhyH and PaH in relevant rodent models. Increased LV contractility could be observed in both types of LV hypertrophy; characteristic distinction was detected in diastolic function (active relaxation) and mechanoenergetics (mechanical efficiency), which might be explained by mitochondrial differences. PMID:26718969

  11. Cerebrospinal Fluid Enhancement on Fluid Attenuated Inversion Recovery Images After Carotid Artery Stenting with Neuroprotective Balloon Occlusions: Hemodynamic Instability and Blood-Brain Barrier Disruption

    SciTech Connect

    Ogami, Ryo Nakahara, Toshinori; Hamasaki, Osamu; Araki, Hayato; Kurisu, Kaoru

    2011-10-15

    Purpose: A rare complication of carotid artery stenting (CAS), prolonged reversible neurological symptoms with delayed cerebrospinal fluid (CSF) space enhancement on fluid attenuated inversion recovery (FLAIR) images, is associated with blood-brain barrier (BBB) disruption. We prospectively identified patients who showed CSF space enhancement on FLAIR images. Methods: Nineteen patients-5 acute-phase and 14 scheduled-underwent 21 CAS procedures. Balloon catheters were navigated across stenoses, angioplasty was performed using a neuroprotective balloon, and stents were placed with after dilation under distal balloon protection. CSF space hyperintensity or obscuration on FLAIR after versus before CAS indicated CSF space enhancement. Correlations with clinical factors were examined. Results: CSF space was enhanced on FLAIR in 12 (57.1%) cases. Postprocedural CSF space enhancement was significantly related to age, stenosis rate, acute-stage procedure, and total occlusion time. All acute-stage CAS patients showed delayed enhancement. Only age was associated with delayed CSF space enhancement in scheduled CAS patients. Conclusions: Ischemic intolerance for severe carotid artery stenosis and temporary neuroprotective balloon occlusion, causing reperfusion injury, seem to be the main factors that underlie BBB disruption with delayed CSF space enhancement shortly after CAS, rather than sudden poststenting hemodynamic change. Our results suggest that factors related to hemodynamic instability or ischemic intolerance seem to be associated with post-CAS BBB vulnerability. Patients at risk for hemodynamic instability or with ischemic intolerance, which decrease BBB integrity, require careful management to prevent intracranial hemorrhagic and other post-CAS complications.

  12. Epigenetic Alterations in Alzheimer's Disease.

    PubMed

    Sanchez-Mut, Jose V; Gräff, Johannes

    2015-01-01

    Alzheimer's disease (AD) is the major cause of dementia in Western societies. It progresses asymptomatically during decades before being belatedly diagnosed when therapeutic strategies have become unviable. Although several genetic alterations have been associated with AD, the vast majority of AD cases do not show strong genetic underpinnings and are thus considered a consequence of non-genetic factors. Epigenetic mechanisms allow for the integration of long-lasting non-genetic inputs on specific genetic backgrounds, and recently, a growing number of epigenetic alterations in AD have been described. For instance, an accumulation of dysregulated epigenetic mechanisms in aging, the predominant risk factor of AD, might facilitate the onset of the disease. Likewise, mutations in several enzymes of the epigenetic machinery have been associated with neurodegenerative processes that are altered in AD such as impaired learning and memory formation. Genome-wide and locus-specific epigenetic alterations have also been reported, and several epigenetically dysregulated genes validated by independent groups. From these studies, a picture emerges of AD as being associated with DNA hypermethylation and histone deacetylation, suggesting a general repressed chromatin state and epigenetically reduced plasticity in AD. Here we review these recent findings and discuss several technical and methodological considerations that are imperative for their correct interpretation. We also pay particular focus on potential implementations and theoretical frameworks that we expect will help to better direct future studies aimed to unravel the epigenetic participation in AD. PMID:26734709

  13. Slow spontaneous hemodynamic oscillations during sleep measured with near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Virtanen, Jaakko; Näsi, Tiina; Noponen, Tommi; Toppila, Jussi; Salmi, Tapani; Ilmoniemi, Risto J.

    2011-07-01

    Spontaneous cerebral hemodynamic oscillations below 100 mHz reflect the level of cerebral activity, modulate hemodynamic responses to tasks and stimuli, and may aid in detecting various pathologies of the brain. Near-infrared spectroscopy (NIRS) is ideally suited for both measuring spontaneous hemodynamic oscillations and monitoring sleep, but little research has been performed to combine these two applications. We analyzed 30 all-night NIRS-electroencephalography (EEG) sleep recordings to investigate spontaneous hemodynamic activity relative to sleep stages determined by polysomnography. Signal power of hemodynamic oscillations in the low-frequency (LF, 40-150 mHz) and very-low-frequency (VLF, 3-40 mHz) bands decreased in slow-wave sleep (SWS) compared to light sleep (LS) and rapid-eye-movement (REM) sleep. No statistically significant (p < 0.05) differences in oscillation power between LS and REM were observed. However, the period of VLF oscillations around 8 mHz increased in REM sleep in line with earlier studies with other modalities. These results increase our knowledge of the physiology of sleep, complement EEG data, and demonstrate the applicability of NIRS to studying spontaneous hemodynamic fluctuations during sleep.

  14. Effect of hemorrhage rate on early hemodynamic responses in conscious sheep.

    PubMed

    Scully, Christopher G; Daluwatte, Chathuri; Marques, Nicole R; Khan, Muzna; Salter, Michael; Wolf, Jordan; Nelson, Christina; Salsbury, John; Enkhbaatar, Perenlei; Kinsky, Michael; Kramer, George C; Strauss, David G

    2016-04-01

    Physiological compensatory mechanisms can mask the extent of hemorrhage in conscious mammals, which can be further complicated by individual tolerance and variations in hemorrhage onset and duration. We assessed the effect of hemorrhage rate on tolerance and early physiologic responses to hemorrhage in conscious sheep. Eight Merino ewes (37.4 ± 1.1 kg) were subjected to fast (1.25 mL/kg/min) and slow (0.25 mL/kg/min) hemorrhages separated by at least 3 days. Blood was withdrawn until a drop in mean arterial pressure (MAP) of >30 mmHg and returned at the end of the experiment. Continuous monitoring includedMAP, central venous pressure, pulmonary artery pressure, pulse oximetry, and tissue oximetry. Cardiac output by thermodilution and arterial blood samples were also measured. The effects of fast versus slow hemorrhage rates were compared for total volume of blood removed and stoppage time (whenMAP < 30 mmHg of baseline) and physiological responses during and after the hemorrhage. Estimated blood volume removed whenMAPdropped 30 mmHg was 27.0 ± 4.2% (mean ± standard error) in the slow and 27.3 ± 3.2% in the fast hemorrhage (P = 0.47, pairedttest between rates). Pressure and tissue oximetry responses were similar between hemorrhage rates. Heart rate increased at earlier levels of blood loss during the fast hemorrhage, but hemorrhage rate was not a significant factor for individual hemorrhage tolerance or hemodynamic responses. In 5/16 hemorrhages MAP stopping criteria was reached with <25% of blood volume removed. This study presents the physiological responses leading up to a significant drop in blood pressure in a large conscious animal model and how they are altered by the rate of hemorrhage. PMID:27044850

  15. Effect of breath holding on cerebrovascular hemodynamics in normal pregnancy and preeclampsia.

    PubMed

    van Veen, Teelkien R; Panerai, Ronney B; Haeri, Sina; Zeeman, Gerda G; Belfort, Michael A

    2015-04-01

    Preeclampsia (PE) is associated with endothelial dysfunction and impaired autonomic function, which is hypothesized to cause cerebral hemodynamic abnormalities. Our aim was to test this hypothesis by estimating the difference in the cerebrovascular response to breath holding (BH; known to cause sympathetic stimulation) between women with preeclampsia and a group of normotensive controls. In a prospective cohort analysis, cerebral blood flow velocity (CBFV) in the middle cerebral artery (transcranial Doppler), blood pressure (BP, noninvasive arterial volume clamping), and end-tidal carbon dioxide (EtCO2) were simultaneously recorded during a 20-s breath hold maneuver. CBFV changes were broken down into standardized subcomponents describing the relative contributions of BP, cerebrovascular resistance index (CVRi), critical closing pressure (CrCP), and resistance area product (RAP). The area under the curve (AUC) was calculated for changes in relation to baseline values. A total of 25 preeclamptic (before treatment) and 25 normotensive women in the second half of pregnancy were enrolled, and, 21 patients in each group were included in the analysis. The increase in CBFV and EtCO2 was similar in both groups. However, the AUC for CVRi and RAP during BH was significantly different between the groups (3.05 ± 2.97 vs. -0.82 ± 4.98, P = 0.006 and 2.01 ± 4.49 vs. -2.02 ± 7.20, P = 0.037), indicating an early, transient increase in CVRi and RAP in the control group, which was absent in PE. BP had an equal contribution in both groups. Women with preeclampsia have an altered initial CVRi response to the BH maneuver. We propose that this is due to blunted sympathetic or myogenic cerebrovascular response in women with preeclampsia. PMID:25614597

  16. Role of GLUT4 on angiotensin 2-induced systemic and renal hemodynamics

    PubMed Central

    Igbe, Ighodaro; Omogbai, Eric Kelly; Oyekan, Adebayo O

    2013-01-01

    Cross-talk between insulin and the renin angiotensin system signaling system shows that angiotensin 2 (A2) negatively modulates insulin signaling by stimulating multiple serine phosphorylation events in the early stages of the insulin-signaling cascade; however, the biological actions of A2 on insulin sensitivity remain controversial. Preservation of glucose transporter 4 (GLUT4) expression during hypertension has been shown to prevent the increased vascular reactivity associated with hypertension. This study tested the hypothesis that GLUT4 contributes to the renal actions of A2. In the euvolemic anesthetized rat, acute infusion of the GLUT4 antagonist, indinavir (1 mg/kg/minute), enhanced an A2-induced increase in mean arterial blood pressure (MABP) (P < 0.01), but attenuated an A2-induced increase in medullary blood flow (MBF) and glomerular filtration rate (P < 0.01). Insulin, a GLUT4 activator (20 mU/kg/minute and 40 mU/kg/minute), decreased basal MABP and urine volume (P < 0.05), but it increased MBF, and these effects were reversed and blunted by indinavir. Subchronic indinavir treatment (80 mg/kg/day orally for 15 days) did not affect A2-induced changes in MABP, cortical blood flow, and MBF, but significantly decreased basal MBF (P < 0.01) and global kidney perfusion (P < 0.05). We concluded that acute but not subchronic inhibition of GLUT4 alters A2-induced changes in systemic and renal hemodynamics by attenuating A2-induced increase in MBF and glomerular filtration rate.

  17. Importance of hemodynamic forces as signals for exercise-induced changes in endothelial cell phenotype

    PubMed Central

    Laughlin, M. Harold; Newcomer, Sean C.; Bender, Shawn B.

    2012-01-01

    Current evidence indicates that the ability of physical activity to sustain a normal phenotype of arterial endothelial cells (ECs) plays a central role in the beneficial effects of exercise (Ex) on atherosclerotic disease. Here we evaluate the strength of evidence that shear stress (SS) and/or circumferential wall stress (stretch) are the primary signals, produced by bouts of Ex, that signal altered gene expression in arterial ECs, thereby resulting in a less atherogenic EC phenotype. Current literature indicates that SS is a signal for expression of antiatherogenic genes in cultured ECs, in ECs of isolated arteries, and in ECs of arteries in intact animals. Furthermore, SS levels in the arteries of humans during Ex are in the range that produces beneficial changes. In contrast, complex flow profiles within recirculation zones and/or oscillatory flow patterns can cause proatherogenic gene expression in ECs. In vivo evidence indicates that Ex decreases oscillatory flow/SS in some portions of the arterial tree but may increase oscillatory flow in other areas of the arterial tree. Circumferential wall stress can increase expression of some beneficial EC genes as well, but circumferential wall stress also increases production of reactive oxygen species and increases the expression of adhesion factors and other proatherogenic genes. Interactions of arterial pressure and fluid SS play an important role in arterial vascular health and likely contribute to how Ex bouts signal changes in EC gene expression. It is also clear that other local and circulating factors interact with these hemodynamic signals during Ex to produce the healthy arterial EC phenotype. We conclude that available evidence suggests that exercise signals formation of beneficial endothelial cell phenotype at least in part through changes in SS and wall stretch in the arteries. PMID:18063803

  18. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics.

    PubMed

    Anupindi, Kameswararao; Delorme, Yann; Shetty, Dinesh A; Frankel, Steven H

    2013-12-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. [Journal of Computational Physics 2010; 229 (23), 8802-8822]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of

  19. A novel multiblock immersed boundary method for large eddy simulation of complex arterial hemodynamics

    PubMed Central

    Shetty, Dinesh A.; Frankel, Steven H.

    2013-01-01

    Computational fluid dynamics (CFD) simulations are becoming a reliable tool to understand hemodynamics, disease progression in pathological blood vessels and to predict medical device performance. Immersed boundary method (IBM) emerged as an attractive methodology because of its ability to efficiently handle complex moving and rotating geometries on structured grids. However, its application to study blood flow in complex, branching, patient-specific anatomies is scarce. This is because of the dominance of grid nodes in the exterior of the fluid domain over the useful grid nodes in the interior, rendering an inevitable memory and computational overhead. In order to alleviate this problem, we propose a novel multiblock based IBM that preserves the simplicity and effectiveness of the IBM on structured Cartesian meshes and enables handling of complex, anatomical geometries at a reduced memory overhead by minimizing the grid nodes in the exterior of the fluid domain. As pathological and medical device hemodynamics often involve complex, unsteady transitional or turbulent flow fields, a scale resolving turbulence model such as large eddy simulation (LES) is used in the present work. The proposed solver (here after referred as WenoHemo), is developed by enhancing an existing in-house high order incompressible flow solver that was previously validated for its numerics and several LES models by Shetty et al. [Journal of Computational Physics 2010; 229 (23), 8802-8822]. In the present work, WenoHemo is systematically validated for additional numerics introduced, such as IBM and the multiblock approach, by simulating laminar flow over a sphere and laminar flow over a backward facing step respectively. Then, we validate the entire solver methodology by simulating laminar and transitional flow in abdominal aortic aneurysm (AAA). Finally, we perform blood flow simulations in the challenging clinically relevant thoracic aortic aneurysm (TAA), to gain insights into the type of

  20. A parameter estimation framework for patient-specific hemodynamic computations

    NASA Astrophysics Data System (ADS)

    Itu, Lucian; Sharma, Puneet; Passerini, Tiziano; Kamen, Ali; Suciu, Constantin; Comaniciu, Dorin

    2015-01-01

    We propose a fully automated parameter estimation framework for performing patient-specific hemodynamic computations in arterial models. To determine the personalized values of the windkessel models, which are used as part of the geometrical multiscale circulation model, a parameter estimation problem is formulated. Clinical measurements of pressure and/or flow-rate are imposed as constraints to formulate a nonlinear system of equations, whose fixed point solution is sought. A key feature of the proposed method is a warm-start to the optimization procedure, with better initial solution for the nonlinear system of equations, to reduce the number of iterations needed for the calibration of the geometrical multiscale models. To achieve these goals, the initial solution, computed with a lumped parameter model, is adapted before solving the parameter estimation problem for the geometrical multiscale circulation model: the resistance and the compliance of the circulation model are estimated and compensated. The proposed framework is evaluated on a patient-specific aortic model, a full body arterial model, and multiple idealized anatomical models representing different arterial segments. For each case it leads to the best performance in terms of number of iterations required for the computational model to be in close agreement with the clinical measurements.

  1. Hemodynamic effects of plasma exchange in septic patients: preliminary report.

    PubMed

    Berlot, G; Gullo, A; Fasiolo, S; Serra, L; Silvestri, L; Wörz, M

    1997-01-01

    To assess the effects of plasma exchange on the hemodynamic performance of septic patients, we studied 12 septic patients (11 males and 1 female, age range 19-64, mean 39 +/- 17 years). After cardiovascular stabilization, plasma exchange was performed in the spontaneous mode via a femorofemoral arteriovenous shunt; during the treatment the infusion rate of cardiovascular drugs and the mechanical ventilation setting were not modified. Heart rate, pulmonary artery occlusion pressure, and peripheral vascular resistance did not change significantly. The stroke volume index increased significantly (from 49 +/- 9 to 60 +/- 9 ml/min/m2; p < 0.05) as well as the cardiac index (from 5.5 +/- 1.2 to 6.3 +/- 0.8 liters/min/m2, the oxygen delivery (from 785 +/- 166 to 872 +/- 118 ml/min/m2; p < 0.05), and the left ventricular stroke work index/pulmonary artery occlusion pressure ratio (from 4.03 +/- 1.92 to 5.07 +/- 2.54; p < 0.05). The oxygen consumption did not change. Four patients survived. In conclusion, in our patients plasma exchange was associated with an improvement in cardiac function, possibly due to the elimination of some sepsis mediator(s) with negative inotropic properties. PMID:9096906

  2. Adrenergic Metabolic and Hemodynamic Effects of Octopamine in the Liver

    PubMed Central

    de Oliveira, Andrea Luiza; de Paula, Mariana Nascimento; Comar, Jurandir Fernando; Vilela, Vanessa Rodrigues; Peralta, Rosane Marina; Bracht, Adelar

    2013-01-01

    The fruit extracts of Citrus aurantium (bitter orange) are traditionally used as weight-loss products and as appetite suppressants. A component of these extracts is octopamine, which is an adrenergic agent. Weight-loss and adrenergic actions are always related to metabolic changes and this work was designed to investigate a possible action of octopamine on liver metabolism. The isolated perfused rat liver was used to measure catabolic and anabolic pathways and hemodynamics. Octopamine increased glycogenolysis, glycolysis, oxygen uptake, gluconeogenesis and the portal perfusion pressure. Octopamine also accelerated the oxidation of exogenous fatty acids (octanoate and oleate), as revealed by the increase in 14CO2 production derived from 14C labeled precursors. The changes in glycogenolysis, oxygen uptake and perfusion pressure were almost completely abolished by α1-adrenergic antagonists. The same changes were partly sensitive to the β-adrenergic antagonist propranolol. It can be concluded that octopamine accelerates both catabolic and anabolic processes in the liver via adrenergic stimulation. Acceleration of oxygen uptake under substrate-free perfusion conditions also means acceleration of the oxidation of endogenous fatty acids, which are derived from lipolysis. All these effects are compatible with an overall stimulating effect of octopamine on metabolism, which is compatible with its reported weight-loss effects in experimental animals. PMID:24196353

  3. Evaluation of Hemodynamic Parameters as Predictors of Glaucoma Progression

    PubMed Central

    Janulevičiene, Ingrida; Ehrlich, Rita; Siesky, Brent; Nedzelskienė, Irena; Harris, Alon

    2011-01-01

    Purpose. To evaluate hemodynamic parameters as possible predictors for glaucoma progression. Methods. An 18-month randomized double-masked cohort study including 30 open-angle glaucoma patients receiving fixed-combination treatment with Dorzolamide/Timolol (DTFC) or Latanoprost/Timolol (LTFC) (n = 15 per group) was performed. Intraocular pressure (IOP), arterial blood pressure (BP), ocular and diastolic perfusion pressures (OPP, DPP), color Doppler imaging, pulsatile ocular blood flow analysis, scanning laser polarimetry, and Humphrey visual field evaluations were included. Results. Both treatments showed statistically similar IOP reduction. Six patients in DTFC and 7 in LTFC group met glaucoma progression criteria. DTFC group had higher OPP, DPP, and lower vascular resistivity indices as compared to the LTFC. Progressing patients had higher nerve fiber index, lower systolic BP, OPP, DPP, higher ophthalmic and central retinal artery vascular resistance, and lower pulse volume (P < .05; t-test). Conclusions. Structural changes consistent with glaucoma progression correlate with non-IOP-dependent risk factors. PMID:21577269

  4. Tube-Load Model Parameter Estimation for Monitoring Arterial Hemodynamics

    PubMed Central

    Zhang, Guanqun; Hahn, Jin-Oh; Mukkamala, Ramakrishna

    2011-01-01

    A useful model of the arterial system is the uniform, lossless tube with parametric load. This tube-load model is able to account for wave propagation and reflection (unlike lumped-parameter models such as the Windkessel) while being defined by only a few parameters (unlike comprehensive distributed-parameter models). As a result, the parameters may be readily estimated by accurate fitting of the model to available arterial pressure and flow waveforms so as to permit improved monitoring of arterial hemodynamics. In this paper, we review tube-load model parameter estimation techniques that have appeared in the literature for monitoring wave reflection, large artery compliance, pulse transit time, and central aortic pressure. We begin by motivating the use of the tube-load model for parameter estimation. We then describe the tube-load model, its assumptions and validity, and approaches for estimating its parameters. We next summarize the various techniques and their experimental results while highlighting their advantages over conventional techniques. We conclude the review by suggesting future research directions and describing potential applications. PMID:22053157