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Sample records for severe hemodynamic alteration

  1. Hemodynamic alterations in chronically conscious unrestrained diabetic rats.

    PubMed

    Carbonell, L F; Salom, M G; Garcia-Estañ, 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. 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/dtmax and dP/dtmin 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 state, possibly conditioning congestive heart failure. These alterations can be prevented by insulin treatment.

  2. 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.

  3. 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.

  4. Clinically significant hemodynamic alterations after propacetamol injection in the emergency department: prevalence and risk factors.

    PubMed

    Bae, June-Il; Ahn, Shin; Lee, Yoon-Seon; Kim, Won Young; Lee, Jae Ho; Oh, Bum Jin; Lim, Kyung Soo

    2017-04-01

    Propacetamol, a water-soluble prodrug form of paracetamol, is hydrolyzed by esterase to generate paracetamol in the blood. Each gram of propacetamol is equal to 0.5 g of paracetamol. It has been reported to cause hypotension in critically ill patients with a fever. We aimed to investigate the hemodynamic effects of propacetamol for the control of fever in patients with diverse severities of illness who were managed in the emergency department (ED). We also aimed to identify clinical factors related to significant hemodynamic alterations in ED patients. This was a retrospective study of 1507 ED patients who received propacetamol. Significant hemodynamic alterations were defined as systolic blood pressure (SBP) <90 mmHg or diastolic blood pressure (DBP) <60 mmHg, or a drop in SBP >30 mmHg, which required treatments with a bolus of fluid or vasopressor administration. Postinfusion SBP and DBP were significantly lower than the preinfusion SBP and DBP. A clinically significant drop in BP occurred in 162 (10.7 %) patients, and interventions were necessary. Among the predictors assessed, congestive heart failure (OR 6.21, 95 % CI 2.67-14.45) and chills (OR 3.10, 95 % CI 2.04-4.70) were independent factors for a significant hemodynamic change. Administration of propacetamol can provoke a reduction in BP in ED patients. This reduction was clinically significant for 10 % of infusions. Clinicians should be aware of this potential deleterious effect, especially in patients with congestive heart failure or who experience chills prior to the administration of propacetamol.

  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 Central

    Secomb, Timothy W.

    2016-01-01

    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 non-uniform 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. Increased Hemodynamic Load in Early Embryonic Stages Alters Endocardial to Mesenchymal Transition

    PubMed Central

    Midgett, Madeline; López, Claudia S.; David, Larry; Maloyan, Alina; Rugonyi, Sandra

    2017-01-01

    Normal blood flow is essential for proper heart formation during embryonic development, as abnormal hemodynamic load (blood pressure and shear stress) results in cardiac defects seen in congenital heart disease. However, the progressive detrimental remodeling processes that relate altered blood flow to cardiac defects remain unclear. Endothelial–mesenchymal cell transition is one of the many complex developmental events involved in transforming the early embryonic outflow tract into the aorta, pulmonary trunk, interventricular septum, and semilunar valves. This study elucidated the effects of increased hemodynamic load on endothelial–mesenchymal transition remodeling of the outflow tract cushions in vivo. Outflow tract banding was used to increase hemodynamic load in the chicken embryo heart between Hamburger and Hamilton stages 18 and 24. Increased hemodynamic load induced increased cell density in outflow tract cushions, fewer cells along the endocardial lining, endocardium junction disruption, and altered periostin expression as measured by confocal microscopy analysis. In addition, 3D focused ion beam scanning electron microscopy analysis determined that a portion of endocardial cells adopted a migratory shape after outflow tract banding that is more irregular, elongated, and with extensive cellular projections compared to normal cells. Proteomic mass-spectrometry analysis quantified altered protein composition after banding that is consistent with a more active stage of endothelial–mesenchymal transition. Outflow tract banding enhances the endothelial–mesenchymal transition phenotype during formation of the outflow tract cushions, suggesting that endothelial–mesenchymal transition is a critical developmental process that when disturbed by altered blood flow gives rise to cardiac malformation and defects. PMID:28228731

  10. Hemodynamic and Metabolic Correlates of Perinatal White Matter Injury Severity

    PubMed Central

    Riddle, Art; Maire, Jennifer; Cai, Victor; Nguyen, Thuan; Gong, Xi; Hansen, Kelly; Grafe, Marjorie R.; Hohimer, A. Roger; Back, Stephen A.

    2013-01-01

    Background and Purpose Although the spectrum of perinatal white matter injury (WMI) in preterm infants is shifting from cystic encephalomalacia to milder forms of WMI, the factors that contribute to this changing spectrum are unclear. We hypothesized that the variability in WMI quantified by immunohistochemical markers of inflammation could be correlated with the severity of impaired blood oxygen, glucose and lactate. Methods We employed a preterm fetal sheep model of in utero moderate hypoxemia and global severe but not complete cerebral ischemia that reproduces the spectrum of human WMI. Since there is small but measurable residual brain blood flow during occlusion, we sought to determine if the metabolic state of the residual arterial blood was associated with severity of WMI. Near the conclusion of hypoxia-ischemia, we recorded cephalic arterial blood pressure, blood oxygen, glucose and lactate levels. To define the spectrum of WMI, an ordinal WMI rating scale was compared against an unbiased quantitative image analysis protocol that provided continuous histo-pathological outcome measures for astrogliosis and microgliosis derived from the entire white matter. Results A spectrum of WMI was observed that ranged from diffuse non-necrotic lesions to more severe injury that comprised discrete foci of microscopic or macroscopic necrosis. Residual arterial pressure, oxygen content and blood glucose displayed a significant inverse association with WMI and lactate concentrations were directly related. Elevated glucose levels were the most significantly associated with less severe WMI. Conclusions Our results suggest that under conditions of hypoxemia and severe cephalic hypotension, WMI severity measured using unbiased immunohistochemical measurements correlated with several physiologic parameters, including glucose, which may be a useful marker of fetal response to hypoxia or provide protection against energy failure and more severe WMI. PMID:24416093

  11. Altered cerebral hemodynamics in early Alzheimer disease: a pilot study using transcranial Doppler.

    PubMed

    Claassen, Jurgen A H R; Diaz-Arrastia, Ramon; Martin-Cook, Kristin; Levine, Benjamin D; Zhang, Rong

    2009-01-01

    Cerebrovascular disease may contribute to the development and progression of Alzheimer's disease (AD). This study investigated whether impairments in cerebral hemodynamics can be detected in early-stage AD. Nine patients with mild AD and eight cognitively normal controls matched for age underwent brain magnetic resonance imaging and neuropsychological evaluation, followed by assessment of steady-state cerebral blood flow velocity (CBFV, transcranial Doppler), blood pressure (BP, Finapres), and cerebrovascular resistance index (BP/CBFV). Cerebral hemodynamics were quantified using spectral and transfer function analysis of BP and CBFV in rest, during standing up after squat, and during repeated squat-stand maneuvers. Compared to controls, AD patients had lower CBFV and higher cerebrovascular resistance index, unexplained by brain atrophy. Low-frequency variability of BP was enhanced, suggesting impaired arterial baroreflex function. However, CBFV variability was reduced despite enhanced BP variability, and dynamic cerebral autoregulation was not impaired. In conclusion, despite a distinct pattern of altered cerebral hemodynamics, AD patients may have normal autoregulation. However, the challenges for autoregulation in AD are higher, as our data show enhanced BP fluctuations. Increased cerebral vasoconstriction or reduced vasomotion also may attenuate CBFV variability.

  12. Hemodynamic effects of a counterpulsation device implanted on the ascending aorta in severe cardiogenic shock.

    PubMed

    Nanas, J N; Nanas, S N; Charitos, C E; Kontoyiannis, D; Poyiadjis, A D; Stamatopoulos, G; Melkaoui, A; Kokollis, G; Moulopoulos, S D

    1988-01-01

    A valveless, single orifice counterpulsation device (CD) with maximum stroke volume of 100 ml was implanted on the ascending aorta of nine dogs. Its pneumatic driver was gaited by the ECG to provide aortic diastolic augmentation, with a stroke volume of 60-70 ml. In the same animals a 20 ml intraaortic balloon (IAB) was placed into the descending aorta. An attempt was made to evaluate the effectiveness of the CD on severe cardiogenic shock and to compare its hemodynamic effects with those of the IABP. Severe cardiogenic shock was induced by coronary artery ligation, propranolol administration, and fluid infusion and was characterized by a LVEDP of 22.2 +/- 6.4 mmHg, ASP less than 70 mmHg and greater than or equal to 30 mmHg, and a reduction of CI by 71.7%. The CD had a significant beneficial effect in all measured parameters. The LVEDP decreased by a mean of 44.3% (P less than 0.001) below control value, and the AEDP by 60.2% (P less than 0.001). The PADA increased by 108.5% (P less than 0.001), and the CI by 155.8% (P less than 0.004). The IABP did not significantly change any of the hemodynamic variables. In conclusion, the CD has significant salutary hemodynamic effects in severe cardiogenic shock where IABP is ineffective.

  13. Hemodynamics in Transplant Renal Artery Stenosis and its Alteration after Stent Implantation Based on a Patient-specific Computational Fluid Dynamics Model

    PubMed Central

    Wang, Hong-Yang; Liu, Long-Shan; Cao, Hai-Ming; Li, Jun; Deng, Rong-Hai; Fu, Qian; Zhang, Huan-Xi; Fei, Ji-Guang; Wang, Chang-Xi

    2017-01-01

    Background: Accumulating studies on computational fluid dynamics (CFD) support the involvement of hemodynamic factors in artery stenosis. Based on a patient-specific CFD model, the present study aimed to investigate the hemodynamic characteristics of transplant renal artery stenosis (TRAS) and its alteration after stent treatment. Methods: Computed tomography angiography (CTA) data of kidney transplant recipients in a single transplant center from April 2013 to November 2014 were reviewed. The three-dimensional geometry of transplant renal artery (TRA) was reconstructed from the qualified CTA images and categorized into three groups: the normal, stenotic, and stented groups. Hemodynamic parameters including pressure distribution, velocity, wall shear stress (WSS), and mass flow rate (MFR) were extracted. The data of hemodynamic parameters were expressed as median (interquartile range), and Mann–Whitney U-test was used for analysis. Results: Totally, 6 normal, 12 stenotic, and 6 stented TRAs were included in the analysis. TRAS presented nonuniform pressure distribution, adverse pressure gradient across stenosis throat, flow vortex, and a separation zone at downstream stenosis. Stenotic arteries had higher maximal velocity and maximal WSS (2.94 [2.14, 3.30] vs. 1.06 [0.89, 1.15] m/s, 256.5 [149.8, 349.4] vs. 41.7 [37.8, 45.3] Pa at end diastole, P = 0.001; 3.25 [2.67, 3.56] vs. 1.65 [1.18, 1.72] m/s, 281.3 [184.3, 364.7] vs. 65.8 [61.2, 71.9] Pa at peak systole, P = 0.001) and lower minimal WSS and MFRs (0.07 [0.03, 0.13] vs. 0.52 [0.45, 0.67] Pa, 1.5 [1.0, 3.0] vs. 11.0 [8.0, 11.3] g/s at end diastole, P = 0.001; 0.08 [0.03, 0.19] vs. 0.70 [0.60, 0.81] Pa, 2.0 [1.3, 3.3] vs. 16.5 [13.0, 20.3] g/s at peak systole, P = 0.001) as compared to normal arteries. Stent implantation ameliorated all the alterations of the above hemodynamic factors except low WSS. Conclusions: Hemodynamic factors were significantly changed in severe TRAS. Stent implantation can restore or

  14. Early evaluation of renal hemodynamic alterations in type I diabetes mellitus with duplex ultrasound.

    PubMed

    Saif, Aasem; Soliman, Neveen A; Abdel-Hameed, Alaa

    2010-03-01

    To evaluate the role of renal duplex ultrasonography in the detection of early alteration of renal blood flow in type I diabetic patients, we studied with duplex ultrasound 32 patients with type I diabetes mellitus (19 males, 13 females, age range 8-19 years) and 35 age and sex-matched controls. The resistivity indices (RIs) and pulsatility indices (PIs) of the main renal as well as intra-renal arteries were calculated. Compared with the healthy control subjects, diabetic patients had significantly higher resistivity indices (RIs) in the intrarenal (segmental, arcuate and interlobar) arteries (P= 0.001). The study, also revealed a significantly positive correlation between the RIs in the intrarenal arteries in diabetics and the albumin/creatinine ratio (r= 0.54, 0.52 and 0.51 respectively), glycated hemoglobin (r= 0.61, 0.59 and 0.63 respectively), as well as the estimated GFR (e-GFR) (r= 0.53, 0.51 and 0.57 respectively). We conclude that the current study documented early intra-renal hemodynamic alterations in the form of pathologically elevated intrarenal RIs. This denotes the potential usefulness of duplex evaluation of the intrarenal arteries, as a noninvasive procedure, for monitoring type 1 diabetic patients to predict those at risk of diabetic nephropathy.

  15. [Hemodynamic correction in children with severe traumatic injuries by the means of transpulmonary hemodilution].

    PubMed

    Lekmanov, A U; Azovskiĭ, D K; Piliutnik, S F; Gegueva, E N

    2011-01-01

    The purpose of the research is t objectify the indications for use of catecholamines and/or change of the infusion therapy volume based on transpulmonary thermodilution in children with severe traumatic injuries. The examined group consisted of 22 children with thermal concomitant or isolated trauma and drowning. All the patents were transferred to the Intensive Care Unit from other hospitals. Hemodynamic parameter estimation was based upon transpulmonary thermodilution. Results indicate, that based upon dynamic assessment of cardiac output, preload (global end diastolic volume index) and postload (systemic vascular resistance index) it is possible to carry out an early targeted correction of the fluid therapy and chose the right type of inotorpic support. Transpulmonary thermodilution in children with severe traumatic injuries allows achieving optimal parameters of blood circulation just 24 hours after its adaption.

  16. 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.

  17. Coagulation defects and altered hemodynamic responses in mice lacking receptors for thromboxane A2.

    PubMed Central

    Thomas, D W; Mannon, R B; Mannon, P J; Latour, A; Oliver, J A; Hoffman, M; Smithies, O; Koller, B H; Coffman, T M

    1998-01-01

    Thromboxane A2 (TXA2) is a labile metabolite of arachidonic acid that has potent biological effects. Its actions are mediated by G protein-coupled thromboxane-prostanoid (TP) receptors. TP receptors have been implicated in the pathogenesis of cardiovascular diseases. To investigate the physiological functions of TP receptors, we generated TP receptor-deficient mice by gene targeting. Tp-/- animals reproduce and survive in expected numbers, and their major organ systems are normal. Thromboxane agonist binding cannot be detected in tissues from Tp-/- mice. Bleeding times are prolonged in Tp-/- mice and their platelets do not aggregate after exposure to TXA2 agonists. Aggregation responses after collagen stimulation are also delayed, although ADP-stimulated aggregation is normal. Infusion of the TP receptor agonist U-46619 causes transient increases in blood pressure followed by cardiovascular collapse in wild-type mice, but U-46619 caused no hemodynamic effect in Tp-/- mice. Tp-/- mice are also resistant to arachidonic acid-induced shock, although arachidonic acid signifi-cantly reduced blood pressure in Tp-/- mice. In summary, Tp-/- mice have a mild bleeding disorder and altered vascular responses to TXA2 and arachidonic acid. Our studies suggest that most of the recognized functions of TXA2 are mediated by the single known Tp gene locus. PMID:9835625

  18. Investigating Non-Invasive Hemodynamic Monitoring Devices Using Severe Dengue as a Surrogate for Trauma-Induced Shock

    DTIC Science & Technology

    2014-12-01

    Devices Using Severe Dengue as a Surrogate for Trauma-Induced Shock” PRINCIPAL INVESTIGATOR: Dr. Stephen Thomas CONTRACTING...Hemodynamic Monitoring Devices Using Severe Dengue as a Surrogate for Trauma-Induced Shock” 5b. GRANT NUMBER W81XWH-12-2-0079 5c. PROGRAM

  19. Altered thyroid function in severely injured patients

    PubMed Central

    Grill, Elena; Strong, Michelle; Sonnad, Seema S.; Sarani, Babak; Pascual, Jose; Collins, Heather; Sims, Carrie A.

    2013-01-01

    Background Hemorrhagic shock profoundly affects the neuroendocrine profile of trauma patients, and we hypothesized that massive resuscitation would negatively impact thyroid function. Methods A prospective, observational study investigating thyroid function in hypotensive trauma patients (systolic blood pressure <90 mm Hg × 2) who survived >48 h was conducted at a Level I center over a 6-mo period. Blood samples for thyroid function were collected at time of presentation to the trauma bay and serially for 48 h. Collected data included demographics, injury data, vital signs, transfusion needs, crystalloid use, and vasopressor requirements. Patients receiving >5 units packed red blood cells (PRBC) within 12 h were compared with those receiving ≥ 5 units. Results Patients who required >5 units of PRBC/12 h had significantly lower total and free T4 levels on initial presentation, and levels remained significantly depressed over the next 48 h when compared with patients who required a less aggressive resuscitative effort. T3 values were markedly suppressed during the initial 48 h post trauma in all patients, but were significantly lower in patients requiring >5 units PRBC. TSH levels remained within the normal range for all time points. Lower trauma admission T4 levels were associated with the need for greater crystalloid resuscitation within the first 24 h. Conclusion Measurements of thyroid function are significantly altered in severely injured patients on initial presentation, and low T4 levels predict the need for large resuscitation. Further research investigating the profile and impact of thyroid function in trauma patients during resuscitation and recovery is warranted. PMID:23043865

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Effects of normoxic and hypoxic exercise regimens on cardiac, muscular, and cerebral hemodynamics suppressed by severe hypoxia in humans.

    PubMed

    Wang, Jong-Shyan; Wu, Min-Huan; Mao, Tso-Yen; Fu, Tieh-cheng; Hsu, Chih-Chin

    2010-07-01

    Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group (n = 12) received one of five interventions: 1) normoxic (21% O(2)) resting control, 2) hypoxic (15% O(2)) resting control, 3) normoxic exercise (50% maximum work rate under 21% O(2); N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O(2); H-RE group), or 5) hypoxic-absolute exercise (50% maximum work rate under 15% O(2); H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Delta total Hb/min) and reoxygenation rate by acute 12% O(2) exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Delta total Hb) and O(2) extraction [Delta deoxyHb] of the VL muscle during the 12% O(2) exercise. Although acute 12% O(2) exercise decreased oxygenation (Delta O(2)Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion and oxygenation during normoxic/hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O(2) delivery/utilization in

  5. Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside.

    PubMed

    Kimmoun, Antoine; Novy, Emmanuel; Auchet, Thomas; Ducrocq, Nicolas; Levy, Bruno

    2015-04-09

    Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.

  6. Sensitivity of neural-hemodynamic coupling to alterations in cerebral blood flow during hypercapnia

    PubMed Central

    Huppert, Theodore J.; Jones, Phill B.; Devor, Anna; Dunn, Andrew K.; Teng, Ivan C.; Dale, Anders M.; Boas, David A.

    2009-01-01

    The relationship between measurements of cerebral blood oxygenation and neuronal activity is highly complex and depends on both neurovascular and neurometabolic biological coupling. While measurements of blood oxygenation changes via optical and MRI techniques have been developed to map functional brain activity, there is evidence that the specific characteristics of these signals are sensitive to the underlying vascular physiology and structure of the brain. Since baseline blood flow and oxygen saturation may vary between sessions and across subjects, functional blood oxygenation changes may be a less reliable indicator of brain activity in comparison to blood flow and metabolic changes. In this work, we use a biomechanical model to examine the relationships between neural, vascular, metabolic, and hemodynamic responses to parametric whisker stimulation under both normal and hypercapnic conditions in a rat model. We find that the relationship between neural activity and oxy- and deoxyhemoglobin changes is sensitive to hypercapnia-induced changes in baseline cerebral blood flow. In contrast, the underlying relationships between evoked neural activity, blood flow, and model-estimated oxygen metabolism changes are unchanged by the hypercapnic challenge. We conclude that evoked changes in blood flow and cerebral oxygen metabolism are more closely associated with underlying evoked neuronal responses. PMID:19725749

  7. Sensitivity of neural-hemodynamic coupling to alterations in cerebral blood flow during hypercapnia

    NASA Astrophysics Data System (ADS)

    Huppert, Theodore J.; Jones, Phill B.; Devor, Anna; Dunn, Andrew K.; Teng, Ivan C.; Dale, Anders M.; Boas, David A.

    2009-07-01

    The relationship between measurements of cerebral blood oxygenation and neuronal activity is highly complex and depends on both neurovascular and neurometabolic biological coupling. While measurements of blood oxygenation changes via optical and MRI techniques have been developed to map functional brain activity, there is evidence that the specific characteristics of these signals are sensitive to the underlying vascular physiology and structure of the brain. Since baseline blood flow and oxygen saturation may vary between sessions and across subjects, functional blood oxygenation changes may be a less reliable indicator of brain activity in comparison to blood flow and metabolic changes. In this work, we use a biomechanical model to examine the relationships between neural, vascular, metabolic, and hemodynamic responses to parametric whisker stimulation under both normal and hypercapnic conditions in a rat model. We find that the relationship between neural activity and oxy- and deoxyhemoglobin changes is sensitive to hypercapnia-induced changes in baseline cerebral blood flow. In contrast, the underlying relationships between evoked neural activity, blood flow, and model-estimated oxygen metabolism changes are unchanged by the hypercapnic challenge. We conclude that evoked changes in blood flow and cerebral oxygen metabolism are more closely associated with underlying evoked neuronal responses.

  8. Multigate quality Doppler profiles and morphological/hemodynamic alterations in multiple sclerosis patients.

    PubMed

    Ciccone, Marco Matteo; Galeandro, Aldo Innocente; Scicchitano, Pietro; Zito, Annapaola; Gesualdo, Michele; Sassara, Marco; Cortese, Francesca; Dachille, Annamaria; Carbonara, Rosa; Federico, Francesco; Livrea, Paolo; Trojano, Maria

    2012-05-01

    Venous echo-color-Doppler (ECD) showed that chronic cerebrospinal venous insufficiency (CCSVI) syndrome is related to multiple sclerosis (MS). Study aims were to assess interobserver variability in ultrasound evaluation of MS patients and to relate echo-markers to MS clinical symptoms and the disability degree. 277 MS patients (117 men, mean age 43.05+10.04 years) admitted to the Neurology Department of Bari University General Hospital, underwent clinical, Expanded Disability Status Scale (EDSS) evaluation, and a cerebro-venous system ECD evaluation. Two operators reevaluated 32 patients to calculate interobserver variability. McNemar test confirmed the procedure reproducibility between two operators (p=ns). Septa/membranes correlated with deep cerebral veins reflux [right: 16% absence vs. 58% presence, p < 0.0001; left: 26% vs. 50%, p < 0.0001]; their absence in Primary Progressive (PP) MS form [right: 11% vs. 2%, p < 0.001; left: 12% vs. 2%, p < 0.001]. Internal jugular veins (IJVs) reflux absence was in Relapsing-remitting (RR) form [right: 60% vs. 74%, p=0.036; left: 56% vs. 85%, p < 0.0001] like hemodynamically significant stenosis [right: 57% vs. 69%, p=0.033; left: 49% vs. 73%, p < 0.001] not present in PP [right: 11% vs. 2%, p < 0.001; left: 10% vs. 3%, p=0.009]. A supine IJVs blocked flow was related to the EDSS class [right: 4.8±1.5 vs. 5.4±1.4, p=0.006; left: 4.7±1.6 vs. 5.5±1.2, p < 0.0001]; its absence was linked to RR [right: 60% vs. 76%, p=0.016; left: 58% vs. 79%, p < 0.001]. ECD has an important value in MS patients with IJV anomalies detection and a good interobserver procedure reproducibility. MS is associated with CCSVI, although further studies are needed.

  9. 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).

  10. 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.

  11. Mechanisms of portal hypertension-induced alterations in renal hemodynamics, renal water excretion, and renin secretion.

    PubMed Central

    Anderson, R J; Cronin, R E; McDonald, K M; Schrier, R W

    1976-01-01

    Clinical states with portal venous hypertension are frequently associated with impairment in renal hemodynamics and water excretion, as well as increased renin secretion. In the present investigation, portal venous pressure (PVP) was increased in anesthetized dogs undergoing a water diuresis. Renal arterial pressure was maintained constant in all studies. As PVP was increased from 6 to 20 mm Hg, decreases in cardiac output (2.5-2.0 liter/min, P less than 0.05) and mean arterial pressure (140-131 mm Hg, P less than 0.05) were observed. Increases in PVP were also associated with decreases in glomerular filtration rate (GFR, 40-31 ml/min, P less than 0.001), renal blood flow (RBF, 276-193 ml/min, P less than 0.001), and increases in renin secretion (232-939 U/min, P less than 0.025) in innervated kidneys. No significant change in either GFR or RBF and a decrease in renin secretion occurred with increases in PVP in denervated kidneys. To dissociate the changes in cardiac output and mean arterial pressure induced by increase PVP from the observed decreases in GFR and RBF, studies were performed on animals undergoing constriction of the thoracic inferior vena cava. In these studies, similar decreases in cardiac output and mean arterial pressure were not associated with significant changes in GFR or RBF. Increases in PVP also were associated with an antidiuresis as urine osmolality increased from 101 to 446 mosmol/kg H2O (P less than 0.001). This antidiuresis was significantly blunted but not abolished by acute hypophysectomy. In hypophysectomized animals, changes in free water clearance and urine flow were linearly correlated as PVP was increased. These studies indicate that increases in PVP result in decreases in GFR and RBF and increases in renin secretion mediated by increased renal adrenergic tone. Increased PVP is also associated with antidiuresis; this antidiuresis is mediated both by vasopressin release and by diminished tubular fluid delivery to the distal

  12. Effect of alterations in femoral artery flow on abdominal vessel hemodynamics in swine.

    PubMed

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

    1999-01-01

    In support of an in vivo investigation in swine of the influence of changes in fluid dynamic wall shear on arterial macromolecular permeability, a procedure has been developed to alter the flows in the porcine posterior arterial vasculature by opening and closing a reversible arteriovenous shunt placed on one of the femoral arteries. Laparoscopic techniques were used to place appropriately modified Transonic Systems ultrasonic flow probes on both external and circumflex iliac arteries, and on the terminal aorta. Flow measurements were made prior to shunt placement, and with the shunt open and closed, to measure the influence of altered external iliac artery flow on the distribution to the infrarenal abdominal vessels. Similar experiments were carried out to relate the flow rates in the external iliac arteries to those in the femoral arteries, which are more accessible. Based on the relationships among the measured flow rates, rules have been developed to estimate the major infrarenal flows in the pig, at baseline and with the shunt opened and closed, from only the flow rates measured at the two femoral arteries.

  13. Intravenous lipid emulsion alters the hemodynamic response to epinephrine in a rat model.

    PubMed

    Carreiro, Stephanie; Blum, Jared; Jay, Gregory; Hack, Jason B

    2013-09-01

    Intravenous lipid emulsion (ILE) is an adjunctive antidote used in selected critically ill poisoned patients. These patients may also require administration of advanced cardiac life support (ACLS) drugs. Limited data is available to describe interactions of ILE with standard ACLS drugs, specifically epinephrine. Twenty rats with intra-arterial and intravenous access were sedated with isoflurane and split into ILE or normal saline (NS) pretreatment groups. All received epinephrine 15 μm/kg intravenously (IV). Continuous mean arterial pressure (MAP) and heart rate (HR) were monitored until both indices returned to baseline. Standardized t tests were used to compare peak MAP, time to peak MAP, maximum change in HR, time to maximum change in HR, and time to return to baseline MAP/HR. There was a significant difference (p = 0.023) in time to peak MAP in the ILE group (54 s, 95 % CI 44-64) versus the NS group (40 s, 95 % CI 32-48) and a significant difference (p = 0.004) in time to return to baseline MAP in ILE group (171 s, 95 % CI 148-194) versus NS group (130 s, 95 % CI 113-147). There were no significant differences in the peak change in MAP, peak change in HR, time to minimum HR, or time to return to baseline HR between groups. ILE-pretreated rats had a significant difference in MAP response to epinephrine; ILE delayed the peak effect and prolonged the duration of effect of epinephrine on MAP, but did not alter the peak increase in MAP or the HR response.

  14. [Hemodynamic effects of intracardiac diatritoic acid and their dependance on left ventricular function and severity of coronary sclerosis (author's transl)].

    PubMed

    Kober, G; Schröder, W; Kaltenbach, M

    1978-07-01

    In 16 patients with coronary heart disease (n = 13) and cardiomyopathy (n = 3) heart rate, left ventricular pressure and contractility (max dp/dt, min dp/dt and Vpm) were measured prior during and after three consecutive left ventricular angiograms. Heart rate decreased during angiography and increased slightly but significantly after angiography. Systolic and diastolic left ventricular pressure, max dp/dt and min dp/dt increased after angiography, whereas Vpm remained unchanged. Any hemodynamic changes occuring were moderate and only of short duration. No significant differences were found a) between patients with angiographically proven normal and reduced left ventricular function, b) between patients with normal or increased left ventricular filling pressure or c) between those with slight or severe coronary heart disease. The investigations point to a good tolerance for the sodium methyl glucamine salt of diatrizoic acid (Urografin 76) even in patients with progressed coronary heart disease. Severe side-effects described in animal experiments indicate a poor comparibility between animal models and human studies. Moreover animal experiments are mostly done with high doses not used clinically.

  15. Intravenous nanosomes of quercetin improve brain function and hemodynamic instability after severe hypoxia in newborn piglets.

    PubMed

    Blasina, Fernanda; Vaamonde, Lucía; Silvera, Fernando; Tedesco, Antonio Claudio; Dajas, Federico

    2015-10-01

    Perinatal asphyxia is a major cause of death and neurological morbidity in newborns and oxidative stress is one of the critical mechanisms leading to permanent brain lesions in this pathology. In this context we have chosen quercetin, a natural antioxidant, known also by its brain protective effects to study its potential as a therapy for brain pathology provoked by severe hypoxia in the brain. To overcame the difficulties of quercetin to access the brain, we have developed lecithin/cholesterol/cyclodextrin nanosomes as a safe and protective vehicle. We have applied the nanosomal preparation intravenously to newborn piglets submitted to a severe hypoxic or ischemic/hypoxic episode and followed them for 8 or 72 h, respectively. Either towards the end of 8 h after hypoxia or up to 72 h after, electroencephalographic amplitude records in animals that received the nanosomes improved significantly. Animals receiving quercetin also stabilized blood pressure and recovered spontaneous breathing. In this experimental group mechanical ventilation assistance was withdrawn in the first 24 h while the hypoxic and vehicle groups required more than 24 h of mechanical ventilation. Three days after the hypoxia the suckling and walking capacity in the group that received quercetin recovered significantly compared with the hypoxic groups. Pathological studies did not show significant differences in the brain of newborn piglets treated with nanosomes compared with hypoxic groups. The beneficial effects of quercetin nanosomal preparation after experimental perinatal asphyxia show it as a promising putative treatment for the damaged brain in development.

  16. Effects of angiotensin-converting enzyme inhibition on altered renal hemodynamics induced by low protein diet in the rat.

    PubMed Central

    Fernández-Repollet, E; Tapia, E; Martínez-Maldonado, M

    1987-01-01

    We assessed the role of angiotensin II in mediating the alterations in renal hemodynamics known to result from low protein feeding to normal rats by examining the effect of the angiotensin-converting enzyme (ACE) inhibitor captopril. 2 wk of low protein (6% casein) diet resulted in decreased glomerular filtration rate (normal protein [NP], 1.82 +/- 0.17 vs. low protein [LP], 0.76 +/- 0.01 ml/min; P less than 0.05) and renal plasma flow (NP, 6.7 +/- 0.2 vs. LP, 3.3 +/- 0.3 ml/min; P less than 0.05); renal vascular resistance rose (NP, 8.7 +/- 0.4 vs. LP, 19.8 +/- 1.4 dyn . s per cm5; P less than 0.05). These changes were accompanied by a significant decrease in plasma renin activity (NP, 7.0 +/- 0.7 vs. LP, 4.4 +/- 0.8 ng A I/ml per h; P less than 0.05), plasma aldosterone concentration (NP, 7.0 +/- 0.6 vs. LP, 4.1 +/- 0.7 ng/dl; P less than 0.05), and urinary PGE2 excretion (NP, 3,120 +/- 511 vs. LP, 648 +/- 95 pg/mgCr; P less than 0.05); by contrast renal renin content was significantly increased (NP, 2,587 +/- 273 vs. LP, 7,032 +/- 654 ng A I/mg protein; P less than 0.05). Treatment with captopril (30 mg/kg per d) raised glomerular filtration rate (GFR; LP + capt, 1.6 +/- 0.2 ml/min) and renal plasma flow (RPF; LP + capt, 6.7 +/- 0.7 ml/min), and reduced renal vascular resistance (LP + capt, 9.2 +/- 0.5 dyn/s per cm5) in low protein-fed animals. These values were not different from those measured in untreated and captopril-treated rats fed a normal (23%) protein diet. There were no changes in systemic mean arterial pressure in any group of rats. These data provide evidence that intrarenal angiotensin II mediates the changes in intrarenal hemodynamics induced by protein deprivation. The effects of low protein feeding may be partly potentiated by the reduction in PGE2 synthesis. However, the normalization of GFR and RPF in view of only modest increases in PGE2 excretion after captopril (LP, 648 +/- 95 vs. LP + capt, 1,131 +/- 82 pg/mgCr; P less than 0.05) suggests

  17. Altered Epithelial Gene Expression in Peripheral Airways of Severe Asthma

    PubMed Central

    Singhania, Akul; Rupani, Hitasha; Jayasekera, Nivenka; Lumb, Simon; Hales, Paul; Gozzard, Neil; Davies, Donna E.

    2017-01-01

    Management of severe asthma remains a challenge despite treatment with glucocorticosteroid therapy. The majority of studies investigating disease mechanisms in treatment-resistant severe asthma have previously focused on the large central airways, with very few utilizing transcriptomic approaches. The small peripheral airways, which comprise the majority of the airway surface area, remain an unexplored area in severe asthma and were targeted for global epithelial gene expression profiling in this study. Differences between central and peripheral airways were evaluated using transcriptomic analysis (Affymetrix HG U133 plus 2.0 GeneChips) of epithelial brushings obtained from severe asthma patients (N = 17) and healthy volunteers (N = 23). Results were validated in an independent cohort (N = 10) by real-time quantitative PCR. The IL-13 disease signature that is associated with an asthmatic phenotype was upregulated in severe asthmatics compared to healthy controls but was predominantly evident within the peripheral airways, as were genes related to mast cell presence. The gene expression response associated with glucocorticosteroid therapy (i.e. FKBP5) was also upregulated in severe asthmatics compared to healthy controls but, in contrast, was more pronounced in central airways. Moreover, an altered epithelial repair response (e.g. FGFBP1) was evident across both airway sites reflecting a significant aspect of disease in severe asthma unadressed by current therapies. A transcriptomic approach to understand epithelial activation in severe asthma has thus highlighted the need for better-targeted therapy to the peripheral airways in severe asthma, where the IL-13 disease signature persists despite treatment with currently available therapy. PMID:28045928

  18. Altered Epithelial Gene Expression in Peripheral Airways of Severe Asthma.

    PubMed

    Singhania, Akul; Rupani, Hitasha; Jayasekera, Nivenka; Lumb, Simon; Hales, Paul; Gozzard, Neil; Davies, Donna E; Woelk, Christopher H; Howarth, Peter H

    2017-01-01

    Management of severe asthma remains a challenge despite treatment with glucocorticosteroid therapy. The majority of studies investigating disease mechanisms in treatment-resistant severe asthma have previously focused on the large central airways, with very few utilizing transcriptomic approaches. The small peripheral airways, which comprise the majority of the airway surface area, remain an unexplored area in severe asthma and were targeted for global epithelial gene expression profiling in this study. Differences between central and peripheral airways were evaluated using transcriptomic analysis (Affymetrix HG U133 plus 2.0 GeneChips) of epithelial brushings obtained from severe asthma patients (N = 17) and healthy volunteers (N = 23). Results were validated in an independent cohort (N = 10) by real-time quantitative PCR. The IL-13 disease signature that is associated with an asthmatic phenotype was upregulated in severe asthmatics compared to healthy controls but was predominantly evident within the peripheral airways, as were genes related to mast cell presence. The gene expression response associated with glucocorticosteroid therapy (i.e. FKBP5) was also upregulated in severe asthmatics compared to healthy controls but, in contrast, was more pronounced in central airways. Moreover, an altered epithelial repair response (e.g. FGFBP1) was evident across both airway sites reflecting a significant aspect of disease in severe asthma unadressed by current therapies. A transcriptomic approach to understand epithelial activation in severe asthma has thus highlighted the need for better-targeted therapy to the peripheral airways in severe asthma, where the IL-13 disease signature persists despite treatment with currently available therapy.

  19. 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

  20. Effects of severe smoke inhalation injury and septic shock on global hemodynamics and microvascular blood flow in sheep.

    PubMed

    Maybauer, Dirk M; Maybauer, Marc O; Traber, Lillian D; Westphal, Martin; Nakano, Yoshimitsu Y; Enkhbaatar, Perenlei; Morita, Naoki; Herndon, David N; Traber, Daniel L

    2006-11-01

    This prospective, randomized, controlled experimental study looks at the effects on global and regional microvascular blood flow (RMBF) in an ovine model of septic shock after severe smoke inhalation injury. Sixteen sheep were randomized into two groups, a control group (no injury, n = 8) and a smoke/sepsis (SS) group (n = 8), which received an insufflation of 4 sets of 12 breaths of cotton smoke (<40 degrees C) followed by instillation of live Pseudomonas aeruginosa into both lung lobes, according to an established protocol. All sheep were mechanically ventilated with 100% oxygen, and fluid resuscitated with lactated Ringer's solution for the entire duration of the 24-h experimental period to maintain hematocrit at baseline (BL) levels. Healthy control animals were not subjected to the injury and received only 4 x 12 breaths of room air and instillation of the vehicle (normal saline). Blood flow was analyzed using colored microspheres. Control animals remained hemodynamically stable and had no statistical changes from BL in visceral or cerebral blood flow during the entire experimental period. All SS animals developed a hypotensive, hyperdynamic circulation, characterized by a significant increase in heart rate and cardiac output with a simultaneous significant fall in mean arterial pressure, which, in combination, led to a fall in systemic vascular resistance index versus BL (P < 0.001, each). In visceral organs, the trachea showed a significant increase in RMBF (P < 0.001). In addition, skeletal muscle significantly increased versus BL and versus controls over time (P < 0.01). Whereas the pancreas displayed a significant drop in RMBF versus BL and controls (P < 0.05), no statistical differences occurred in the renal cortex, spleen, and ileum. All investigated cerebral structures, such as the cortex cerebri, basal ganglia, thalamus, hippocampus, pons, medulla oblongata, and cerebellum showed a significant increase in RMBF versus BL and versus control animals (P

  1. Altered Insular Function during Aberrant Salience Processing in Relation to the Severity of Psychotic Symptoms

    PubMed Central

    Walter, Anna; Suenderhauf, Claudia; Smieskova, Renata; Lenz, Claudia; Harrisberger, Fabienne; Schmidt, André; Vogel, Tobias; Lang, Undine E.; Riecher-Rössler, Anita; Eckert, Anne; Borgwardt, Stefan

    2016-01-01

    There is strong evidence for abnormal salience processing in patients with psychotic experiences. In particular, there are indications that the degree of aberrant salience processing increases with the severity of positive symptoms. The aim of the present study was to elucidate this relationship by means of brain imaging. Functional magnetic resonance imaging was acquired to assess hemodynamic responses during the Salience Attribution Test, a paradigm for reaction time that measures aberrant salience to irrelevant stimulus features. We included 42 patients who were diagnosed as having a psychotic disorder and divided them into two groups according to the severity of their positive symptoms. Whole brain analysis was performed using Statistical Parametric Mapping. We found no significant behavioral differences with respect to task performance. Patients with more positive symptoms showed increased hemodynamic responses in the left insula corresponding to aberrant salience than in patients with less positive symptoms. In addition, left insula activation correlated negatively with cumulative antipsychotic medication. Aberrant salience processing in the insula may be increased in psychosis, depending on the severity of positive symptoms. This study indicates that clinically similar psychosis manifestations share the same functional characteristics. In addition, our results suggest that antipsychotic medication can modulate insular function. PMID:27933003

  2. Changes in B-type Natriuretic Peptide and Related Hemodynamic Parameters Following a Fluid Challenge in Critically Ill Patients with Severe Sepsis or Septic Shock

    PubMed Central

    Omar, Shahed; Ali, Ahmad; Atiya, Yahya; Mathivha, Rudo Lufuno; Dulhunty, Joel M.

    2017-01-01

    Context: Severe sepsis or septic shock. Aims: The aim of this study is to examine the effect of a fluid challenge on the B-type natriuretic peptide (BNP) and the hemodynamic state. Settings and Design: This observational study was conducted in an intensivist-led academic, mixed medical-surgical Intensive Care Unit. Subjects and Methods: Focused transthoracic echocardiogram, plasma BNP, and hemodynamic measurements were recorded at baseline and following a 500 ml fluid challenge in thirty patients. Independent predictors of the percentage (%) change in stroke volume (SV) were sought. Next, these independent predictors were assessed for a relationship with the percentage change in BNP. Statistical Analysis Used: Multiple linear regressions, Wilcoxon rank-sum test, t-test, and Pearson's correlation were used. Data analysis was carried out using SAS. The 5% significance level was used. Results: Using a multiple regression models, the percentage increase in SV was independently predicted by the percentage increase in mean arterial pressure, left ventricular end-diastolic volume/dimension (LVEDV/LVEDd), ejection fraction, and a decrease in Acute Physiology and Chronic Health Evaluation II score (P < 0.0001). Preload, measured using LVEDV1 (before the fluid challenge) was significantly larger in the fluid nonresponders (%SV increase <15%) vs. the responders (%SV increase ≥15%). Finally, the percentage change in BNP was positively correlated with left ventricular size at end diastole LVEDd, r = 0.4, P < 0.035). Conclusions: An increase in BNP soon after a fluid challenge may have some predictive utility of a large LVEDd, which in turn can be used to independently predict the SV response to a fluid challenge.

  3. Statins and cerebral hemodynamics

    PubMed Central

    Giannopoulos, Sotirios; Katsanos, Aristeidis H; Tsivgoulis, Georgios; Marshall, Randolph S

    2012-01-01

    HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA. PMID:22929438

  4. 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.

  5. Asiatic acid alleviates hemodynamic and metabolic alterations via restoring eNOS/iNOS expression, oxidative stress, and inflammation in diet-induced metabolic syndrome rats.

    PubMed

    Pakdeechote, Poungrat; Bunbupha, Sarawoot; Kukongviriyapan, Upa; Prachaney, Parichat; Khrisanapant, Wilaiwan; Kukongviriyapan, Veerapol

    2014-01-16

    Asiatic acid is a triterpenoid isolated from Centella asiatica. The present study aimed to investigate whether asiatic acid could lessen the metabolic, cardiovascular complications in rats with metabolic syndrome (MS) induced by a high-carbohydrate, high-fat (HCHF) diet. Male Sprague-Dawley rats were fed with HCHF diet with 15% fructose in drinking water for 12 weeks to induce MS. MS rats were treated with asiatic acid (10 or 20 mg/kg/day) or vehicle for a further three weeks. MS rats had an impairment of oral glucose tolerance, increases in fasting blood glucose, serum insulin, total cholesterol, triglycerides, mean arterial blood pressure, heart rate, and hindlimb vascular resistance; these were related to the augmentation of vascular superoxide anion production, plasma malondialdehyde and tumor necrosis factor-alpha (TNF-α) levels (p<0.05). Plasma nitrate and nitrite (NOx) were markedly high with upregulation of inducible nitric oxide synthase (iNOS) expression, but dowregulation of endothelial nitric oxide synthase (eNOS) expression (p<0.05). Asiatic acid significantly improved insulin sensitivity, lipid profiles, hemodynamic parameters, oxidative stress markers, plasma TNF-α, NOx, and recovered abnormality of eNOS/iNOS expressions in MS rats (p<0.05). In conclusion, asiatic acid improved metabolic, hemodynamic abnormalities in MS rats that could be associated with its antioxidant, anti-inflammatory effects and recovering regulation of eNOS/iNOS expression.

  6. Factors associated with hyperdynamic or hypodynamic circulation and role of platelet-activating factor in hemodynamic alterations in bacterial peritonitis in conscious rats.

    PubMed

    Novo, C; Ais, G; López-Farré, A; Romeo, J M; Pérez-Barriocanal, F; López-Novoa, J M

    1995-12-01

    Male Wistar rats injected intraperitoneally (i.p.) with 10(9) U Escherichia coli ATCC 25922 developed acute bacterial peritonitis. Hemodynamic studies, with microspheres labeled with 103Ru 57Co, and 113Sn, were performed before, 30 min after bacterial injection, and 30 min after administration of either the platelet-activating factor (PAF) antagonist BN-52021 (5 mg/kg body weight) or isotonic saline. A blood sample of 0.3 ml was obtained for bacterial culture and endotoxemia measurements. Plasma PAF levels were measured in a different group of 10 control rats and 20 animals with experimental peritonitis. One group of rats injected with E. coli (n = 13) displayed hyperdynamic circulation, with an increase in cardiac output (CO) from 15.1 +/- 1.2 to 19.4 +/- 1.1 ml/min/100 g body weight and a decrease in total peripheral resistance (TPR) from 19.5 +/- 2.4 to 14.9 +/- 1.1 dynes.s.cm-5 10(-4). Furthermore, these rats showed high endotoxin blood concentrations and low hemoculture levels. The remaining 7 peritonitic rats showed a significant decrease in CO from 16.3 +/- 1.6 to 12.7 +/- 1.2 ml/min/100 g body weight and an increase in TPR from 17.3 +/- 1.8 to 22.6 +/- 2.8 dynes.s.cm-5 10(-4). In addition, these rats showed low endotoxin blood concentrations and high hemoculture levels. Endotoxin blood concentrations were positively correlated with the change in CO (r = 0.87, p < 0.05), and cell hemocultures were positively correlated with CO (r = 0.89, p < 0.05). Rats with high endotoxin blood levels showed higher PAF plasma levels than control rats or peritonitic rats with low endotoxin blood levels. When peritonitic rats were injected with the specific PAF-receptor blocker BN-52021 (5 mg/kg body weight) as a bolus, CO and TPR returned to baseline values in both groups of animals. These data suggest that the hemodynamic changes induced by bacterial peritonitis depend on endotoxemia and bacteremia in opposite ways. In addition, PAF appears to be involved in both the

  7. Severe dyspnoea with alteration of the diffusion capacity of the lung associated with fingolimod treatment.

    PubMed

    Bianco, Assunta; Patanella, Agata Katia; Nociti, Viviana; De Fino, Chiara; Lucchini, Matteo; Savio, Francesco Lo; Rossini, Paolo Maria; Mirabella, Massimiliano

    2016-09-01

    In phase II clinical trial, fingolimod at a dose of 5.0mg (ten times higher than the currently approved dose) induced dyspnoea and decreased forced expiratory flow in some patients, probably trought an airways constriction S1P4-mediated. In phase III trials, respiratory adverse events associated with fingolimod treatment as dyspnoea, cough, oropharingeal pain and nasal congestion are reported with the same incidence of placebo. Here we report two cases of severe dyspnoea with alteration of the diffusion capacity of the lung associated with fingolimod treatment, which led to permanent treatment withdrawal.

  8. Effects of Obesity on Cardiovascular Hemodynamics, Cardiac Morphology, and Ventricular Function.

    PubMed

    Alpert, Martin A; Omran, Jad; Bostick, Brian P

    2016-12-01

    Obesity produces a variety of hemodynamic alterations that may cause changes in cardiac morphology which predispose to left and right ventricular dysfunction. Various neurohormonal and metabolic alterations commonly associated with obesity may contribute to these abnormalities of cardiac structure and function. These changes in cardiovascular hemodynamics, cardiac morphology, and ventricular function may, in severely obese patients, predispose to heart failure, even in the absence of other forms of heart disease (obesity cardiomyopathy). In normotensive obese patients, cardiac involvement is commonly characterized by elevated cardiac output, low peripheral vascular resistance, and increased left ventricular (LV) end-diastolic pressure. Sleep-disordered breathing may lead to pulmonary arterial hypertension and, in association with left heart failure, may contribute to elevation of right heart pressures. These alterations, in association with various neurohormonal and metabolic abnormalities, may produce LV hypertrophy; impaired LV diastolic function; and less commonly, LV systolic dysfunction. Many of these alterations are reversible with substantial voluntary weight loss.

  9. Maternal effects alter the severity of inbreeding depression in the offspring.

    PubMed

    Pilakouta, Natalie; Smiseth, Per T

    2016-09-14

    A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreeding depression in the offspring. Inbreeding depression is a reduction in the fitness of inbred offspring relative to outbred offspring. Here, we tested whether maternal effects due to body size alter the magnitude of inbreeding depression in the burying beetle Nicrophorus vespilloides We found that inbreeding depression in larval survival was more severe for offspring of large females than offspring of small females. This might be due to differences in how small and large females invest in an inbred brood because of their different prospects for future breeding opportunities. To our knowledge, this is the first evidence for a causal effect of the maternal phenotype on the severity of inbreeding depression in the offspring. In natural populations that are subject to inbreeding, maternal effects may drive variation in inbreeding depression and therefore contribute to variation in the strength and direction of selection for inbreeding avoidance.

  10. 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

  11. Hemodynamic monitoring in the critically ill: an overview of current cardiac output monitoring methods

    PubMed Central

    Huygh, Johan; Peeters, Yannick; Bernards, Jelle; Malbrain, Manu L. N. G.

    2016-01-01

    Critically ill patients are often hemodynamically unstable (or at risk of becoming unstable) owing to hypovolemia, cardiac dysfunction, or alterations of vasomotor function, leading to organ dysfunction, deterioration into multi-organ failure, and eventually death. With hemodynamic monitoring, we aim to guide our medical management so as to prevent or treat organ failure and improve the outcomes of our patients. Therapeutic measures may include fluid resuscitation, vasopressors, or inotropic agents. Both resuscitation and de-resuscitation phases can be guided using hemodynamic monitoring. This monitoring itself includes several different techniques, each with its own advantages and disadvantages, and may range from invasive to less- and even non-invasive techniques, calibrated or non-calibrated. This article will discuss the indications and basics of monitoring, further elaborating on the different techniques of monitoring. PMID:28003877

  12. Recovery from renal ischemia-reperfusion injury is associated with altered renal hemodynamics, blunted pressure natriuresis, and sodium-sensitive hypertension.

    PubMed

    Pechman, Kimberly R; De Miguel, Carmen; Lund, Hayley; Leonard, Ellen C; Basile, David P; Mattson, David L

    2009-11-01

    The present studies evaluated intrarenal hemodynamics, pressure natriuresis, and arterial blood pressure in rats following recovery from renal ischemia-reperfusion (I/R) injury. Acute I/R injury, induced by 40 min of bilateral renal arterial occlusion, resulted in an increase in plasma creatinine that resolved within a week. Following 5 wk of recovery on a 0.4% NaCl diet, the pressure-natriuresis response was assessed in anesthetized rats in which the kidney was denervated and extrarenal hormones were administered intravenously. Increasing renal perfusion pressure (RPP) from 107 to 141 mmHg resulted in a fourfold increase in urine flow and sodium excretion in sham control rats. In comparison, pressure diuresis and natriuresis were significantly attenuated in post-I/R rats. In sham rats, glomerular filtration rate (GFR) averaged 1.6 +/- 0.2 mlxmin(-1)xg kidney weight(-1) and renal blood flow (RBF) averaged 7.8 +/- 0.7 mlxmin(-1)xg kidney weight(-1) at RPP of 129 mmHg. Renal cortical blood flow, measured by laser-Doppler flowmetry, was well autoregulated whereas medullary blood flow and renal interstitial hydrostatic pressure increased directly with elevated RPP in sham rats. In contrast, GFR and RBF were significantly reduced whereas medullary perfusion and interstitial pressure demonstrated an attenuated response to RPP in post-I/R rats. Further experiments demonstrated that conscious I/R rats develop hypertension when sodium intake is increased. The present data indicate that the pressure-natriuretic-diuretic response in I/R rats is blunted because of a decrease in GFR and RBF and the depressed pressure-dependent increase in medullary blood flow and interstitial pressure.

  13. Chronic ethanol feeding increases the severity of Staphylococcus aureus skin infections by altering local host defenses.

    PubMed

    Parlet, Corey P; Kavanaugh, Jeffrey S; Horswill, Alexander R; Schlueter, Annette J

    2015-04-01

    Alcoholics are at increased risk of Staphylococcus aureus skin infection and serious sequelae, such as bacteremia and death. Despite the association between alcoholism and severe S. aureus skin infection, the impact of EtOH on anti-S. aureus cutaneous immunity has not been investigated in a model of chronic EtOH exposure. To test the hypothesis that EtOH enhances the severity of S. aureus skin infection, mice were fed EtOH for ≥12 weeks via the Meadows-Cook model of alcoholism and inoculated with S. aureus following epidermal abrasion. Evidence of exacerbated staphylococcal disease in EtOH-fed mice included: skin lesions that were larger and contained more organisms, greater weight loss, and increased bacterial dissemination. Infected EtOH-fed mice demonstrated poor maintenance and induction of PMN responses in skin and draining LNs, respectively. Additionally, altered PMN dynamics in the skin of these mice corresponded with reduced production of IL-23 and IL-1β by CD11b(+) myeloid cells and IL-17 production by γδ T cells, with the latter defect occurring in the draining LNs as well. In addition, IL-17 restoration attenuated S. aureus-induced dermatopathology and improved bacterial clearance defects in EtOH-fed mice. Taken together, the findings show, in a novel model system, that the EtOH-induced increase in S. aureus-related injury/illness corresponds with defects in the IL-23/IL-17 inflammatory axis and poor PMN accumulation at the site of infection and draining LNs. These findings offer new information about the impact of EtOH on cutaneous host-defense pathways and provide a potential mechanism explaining why alcoholics are predisposed to S. aureus skin infection.

  14. 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.

  15. TFIIH subunit alterations causing xeroderma pigmentosum and trichothiodystrophy specifically disturb several steps during transcription.

    PubMed

    Singh, Amita; Compe, Emanuel; Le May, Nicolas; Egly, Jean-Marc

    2015-02-05

    Mutations in genes encoding the ERCC3 (XPB), ERCC2 (XPD), and GTF2H5 (p8 or TTD-A) subunits of the transcription and DNA-repair factor TFIIH lead to three autosomal-recessive disorders: xeroderma pigmentosum (XP), XP associated with Cockayne syndrome (XP/CS), and trichothiodystrophy (TTD). Although these diseases were originally associated with defects in DNA repair, transcription deficiencies might be also implicated. By using retinoic acid receptor beta isoform 2 (RARB2) as a model in several cells bearing mutations in genes encoding TFIIH subunits, we observed that (1) the recruitment of the TFIIH complex was altered at the activated RARB2 promoter, (2) TFIIH participated in the recruitment of nucleotide excision repair (NER) factors during transcription in a manner different from that observed during NER, and (3) the different TFIIH variants disturbed transcription by having distinct consequences on post-translational modifications of histones, DNA-break induction, DNA demethylation, and gene-loop formation. The transition from heterochromatin to euchromatin was disrupted depending on the variant, illustrating the fact that TFIIH, by contributing to NER factor recruitment, orchestrates chromatin remodeling. The subtle transcriptional differences found between various TFIIH variants thus participate in the phenotypic variability observed among XP, XP/CS, and TTD individuals.

  16. Severe pulmonary hypertension is associated with altered right ventricle metabolic substrate uptake

    PubMed Central

    Kumar, Rahul; Mickael, Claudia; Sanders, Linda; Gebreab, Liya; Huber, Kendra M.; Perez, Mario; Smith-Jones, Peter; Serkova, Natalie J.; Tuder, Rubin M.

    2015-01-01

    In severe pulmonary hypertension (SPH), prior studies have shown an increase in right ventricle (RV) uptake of glucose, but it is unclear whether there is a change in the relative utilization of fatty acids. We hypothesized that in the RV in SPH, as in left ventricular (LV) failure, there is altered substrate utilization, with increased glucose uptake and decreased fatty acid uptake. SPH was induced in rats by treatment with the VEGF receptor inhibitor SU5416 and 3 wk of hypoxia (10% FiO2), followed by an additional 4 wk of normoxia (SU-Hx group). Control rats were treated with carboxymethylcellulose vehicle and 7 wk of normoxia (CMC-Nx group). The rodents then underwent positron emission tomography with sequential administration of two radiotracers, 2-deoxy-2-[18F]fluoroglucose (18F-FDG) and 14-(R,S)-[18F]fluoro-6-thia-heptadecanoic acid (18F-FTHA), analogs of glucose and fatty acid, respectively. Five CMC-Nx and 3 SU-Hx rats completed the entire experimental protocol. In the RV, there was a mild increase in 18F-FDG uptake (1.35-fold, P = 0.085) and a significant decrease in 18F-FTHA uptake (−2.1-fold, P < 0.05) in the SU-Hx rats relative to the CMC-Nx rats. In the LV, SU-Hx rats had less uptake of both radiotracers compared with CMC-Nx rats. Less RV fatty acid uptake in SPH was corroborated by decreased fatty acid transporters and enzymes in the RV tissue, and specifically a decrease in lipoprotein lipase. In the RV in rats with SPH, there is a major shift in metabolic substrate preference, largely due to decreased fatty acid uptake. PMID:26115672

  17. 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

  18. QUANTIFICATION OF LOCAL HEMODYNAMIC ALTERATIONS CAUSED BY VIRTUAL IMPLANTATION OF THREE COMMERCIALLY-AVAILABLE STENTS FOR THE TREATMENT OF AORTIC COARCTATION

    PubMed Central

    Kwon, Sung; Feinstein, Jeffrey A.; Dholakia, Ronak J.; LaDisa, John F.

    2014-01-01

    Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of GenesisXD and modified NumedCP stents also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure (BP) data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured data and generate blood flow velocity and time-averaged WSS (TAWSS) results. TAWSS was quantified longitudinally and circumferentially in the stented region and dAo. While modest differences were seen in the distal portion of the stented region, marked differences were observed downstream along the posterior dAo and depended on stent type. The GenesisXD model had the least area of TAWSS values exceeding the threshold for platelet aggregation in vitro, followed by the Palmaz and NumedCP stents. Alterations in local blood flow patterns and WSS imparted on the dAo appear to depend on the type of stent implanted for CoA. Following confirmation in larger studies, these findings may aid pediatric interventional cardiologists in selecting the most appropriate stent for each patient, and ultimately reduce long-term morbidity following treatment for CoA by stenting. PMID:24259013

  19. Altered Trafficking and Processing of GALC Mutants Correlates with Globoid Cell Leukodystrophy Severity

    PubMed Central

    Feltri, M. Laura; Wrabetz, Lawrence

    2016-01-01

    Globoid cell leukodystrophy (GLD, Krabbe disease) is due to autosomal recessive mutations in the lysosomal enzyme galactosylceramidase (GALC). Many GLD patients develop infantile-onset of progressive neurologic deterioration and death by 2 years of age, whereas others have a later-onset, milder disease. Cord blood transplant slows disease progression much more effectively when performed presymptomatically, highlighting the importance of early diagnosis. Current diagnosis is based on reduced GALC activity, DNA sequence, and clinical examination. However, presymptomatic diagnosis is hampered by imperfect genotype-GALC activity-phenotype correlations. In addition, three polymorphisms in the GALC gene are variably associated with disease mutations and have unknown effects on GALC activity and disease outcome. Here, we study mutations that cause infantile or later-onset GLD, and show that GALC activity is significantly lower in infantile versus later-onset mutants when measured in the lysosomal fraction, but not in whole-cell lysates. In parallel, infantile-onset mutant GALCs showed reduced trafficking to lysosomes and processing than later-onset mutant GALCs. Finally, the cis-polymorphisms also affected trafficking to the lysosome and processing of GALC. These differences potentially explain why the activity of different mutations appears similar in whole-cell extracts from lymphocytes, and suggest that measure of GALC activity in lysosomes may better predict the onset and severity of disease for a given GLD genotype. SIGNIFICANCE STATEMENT Globoid cell leukodystrophy (GLD, Krabbe disease) is diagnosed by measuring galactosylceramidase (GALC) activity and DNA analysis. However, genotype and phenotype often do not correlate due to considerable clinical variability, even for the same mutation, for unknown reasons. We find that altered trafficking to the lysosome and processing of GALC correlates with GLD severity and is modulated by cis-polymorphisms. Current diagnosis

  20. Invasive hemodynamics of constrictive pericarditis.

    PubMed

    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.

  1. Curcumin prevents maleate-induced nephrotoxicity: relation to hemodynamic alterations, oxidative stress, mitochondrial oxygen consumption and activity of respiratory complex I.

    PubMed

    Tapia, E; Sánchez-Lozada, L G; García-Niño, W R; García, E; Cerecedo, A; García-Arroyo, F E; Osorio, H; Arellano, A; Cristóbal-García, M; Loredo, M L; Molina-Jijón, E; Hernández-Damián, J; Negrette-Guzmán, M; Zazueta, C; Huerta-Yepez, S; Reyes, J L; Madero, M; Pedraza-Chaverrí, J

    2014-11-01

    The potential protective effect of the dietary antioxidant curcumin (120 mg/Kg/day for 6 days) against the renal injury induced by maleate was evaluated. Tubular proteinuria and oxidative stress were induced by a single injection of maleate (400 mg/kg) in rats. Maleate-induced renal injury included increase in renal vascular resistance and in the urinary excretion of total protein, glucose, sodium, neutrophil gelatinase-associated lipocalin (NGAL) and N-acetyl β-D-glucosaminidase (NAG), upregulation of kidney injury molecule (KIM)-1, decrease in renal blood flow and claudin-2 expression besides of necrosis and apoptosis of tubular cells on 24 h. Oxidative stress was determined by measuring the oxidation of lipids and proteins and diminution in renal Nrf2 levels. Studies were also conducted in renal epithelial LLC-PK1 cells and in mitochondria isolated from kidneys of all the experimental groups. Maleate induced cell damage and reactive oxygen species (ROS) production in LLC-PK1 cells in culture. In addition, maleate treatment reduced oxygen consumption in ADP-stimulated mitochondria and diminished respiratory control index when using malate/glutamate as substrate. The activities of both complex I and aconitase were also diminished. All the above-described alterations were prevented by curcumin. It is concluded that curcumin is able to attenuate in vivo maleate-induced nephropathy and in vitro cell damage. The in vivo protection was associated to the prevention of oxidative stress and preservation of mitochondrial oxygen consumption and activity of respiratory complex I, and the in vitro protection was associated to the prevention of ROS production.

  2. 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.

  3. 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

  4. Altered hemodynamics and hyperuricemia accompany an elevated sFlt-1/PlGF ratio before the onset of early severe preeclampsia.

    PubMed

    Doherty, Anne; Carvalho, Jose C A; Drewlo, Sascha; El-Khuffash, Afif; Downey, Kristi; Dodds, Madelaine; Kingdom, John

    2014-08-01

    Objectifs : L’identification précoce des femmes exposées à des risques d’en venir à présenter une prééclampsie grave d’apparition précoce (PEg) constitue un objectif clé en obstétrique. La constatation d’un rapport sFlt-1 (tyrosine kinase 1 de type fms soluble) - PlGF (facteur de croissance placentaire) (rapport sFlt-1/PlGF) élevé précède celle d’une hypertension patente. La relation longitudinale entre ce marqueur biologique, l’hémodynamique maternelle et le taux sérique maternel d’acide urique au cours de la phase préclinique est inconnue. Devis de l’étude : Nous avons suivi, de 20 semaines jusqu’à l’accouchement ou 34 semaines de gestation, 20 femmes normotendues exposées à un risque élevé d’en venir à présenter une PEg. Un monitorage hémodynamique non effractif (faisant appel à la technologie de la bioréactance) à été mené à 20-22, à 24-26, à 28-30 et à 32-34 semaines de gestation. Les taux sériques d’acide urique, de sFlt-1 et de PlGF ont été mesurés simultanément. Résultats : Six des 20 femmes (30 %) ont accouché avant 33 semaines et présentaient une PEg; elles présentaient une résistance vasculaire périphérique totale (RVPT) moyenne considérablement plus élevée, un taux sérique d’acide urique accru et des rapports sFlt-1/PlGF plus élevés à 24 semaines de gestation que les femmes non affectées. La surface sous la courbe, les valeurs seuils et la sensibilité / spécificité pour ce qui est de la prévision de la PEg à 24 semaines étaient les suivantes : RVPT = 0,84, 1 250 dyne.s.cm-5, 80 %, 93 %; rapport sFlt-1/PlGF = 0,94, 55, 100 %, 93 %; et taux sérique d’acide urique = 0,99, 255 μmol/l, 100 %, 93 %. La RVPT et la sFlt-1 présentaient une corrélation positive au sein du groupe PEg avant la mise en œuvre d’un traitement antihypertenseur (r = 0,65, P = 0,01). Le taux sérique d’acide urique présentait une corrélation tant avec la sFlt-1 (r = 0,65, P = 0,003) qu’avec le rapport sFlt-1/PlGF (r = 0,54, P = 0,02). Conclusion : La combinaison « détermination non effractive de la RVPT-mesure du taux sérique d’acide urique » pourrait permettre l’identification d’un sous-ensemble de femmes qui sont exposées à un risque élevé sur le plan clinique et qui présentent une PEg évolutive, sans devoir avoir recours à la détermination du rapport sFlt-1/PlGF. La valeur prédictive de cette approche intégrée doit être évaluée auprès d’une cohorte de femmes de plus grande envergure afin d’en confirmer davantage l’utilité.

  5. The Acute Impact of Smoking One Cigarette on Cardiac Hemodynamic Parameters

    PubMed Central

    Farha, Khalid Abou; AbouFarha, Ramy; Bolt, Marc

    2011-01-01

    Background The acute impact of tobacco smoking on the cardiac hemodynamic parameters and its pathological implication in the process of arterial atherosclerosis need further exploration. This investigation was purposed to assess the acute impact of tobacco smoke on blood pressure and cardiac hemodynamic parameters. Methods Using an Ultrasonic Cardiac Output Monitor, and DINAMAP Pro 400 Series V2 blood pressure monitor, several cardiac hemodynamic parameters and the blood pressure were assessed in 14 smokers, 11 females and 3 males, at 2 time points, before and after smoking of one cigarette. Data, in terms of ratio of the means and 95% confidence interval were analyzed using ANOVA. Results Single-subject design in which the subject has served as his/her own control has been used. Tobacco smoking led to statistically significant acute increase in the means of all hemodynamic parameters, except for heart rate in female subjects, as compared to the means obtained before smoking. Conclusions Cigarette smoking induces acute non-physiologic alteration in cardiac outflow forces, exposing the aortic valve and arch to mechanical injury that might be implicated in initiating and promoting the process of aortic arch atherosclerosis and associated pathological lesions.

  6. Hemodynamic effects of red blood cell aggregation.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2007-01-01

    The influence of red blood cell (RBC) aggregation on blood flow in vivo has been under debate since early 1900's, yet a full understanding has still has not been reached. Enhanced RBC aggregation is well known to increase blood viscosity measured in rotational viscometers. However, it has been demonstrated that RBC aggregation may decrease flow resistance in cylindrical tubes, due to the formation of a cell-poor zone near the tube wall which results from the enhanced central accumulation of RBC. There is also extensive discussion regarding the effects of RBC aggregation on in vivo blood flow resistance. Several groups have reported increased microcirculatory flow resistance with enhanced RBC aggregation in experiments that utilized intravital microscopy. Alternatively, whole organ studies revealed that flow resistance may be significantly decreased if RBC aggregation is enhanced. Recently, new techniques have been developed to achieve well-controlled, graded alterations in RBC aggregation without influencing suspending phase properties. Studies using this technique revealed that the effects of RBC aggregation are determined by the degree of aggregation changes, and that this relationship can be explained by different hemodynamic mechanisms.

  7. Inflammatory Serum Proteins Are Severely Altered in Metastatic Gastric Adenocarcinoma Patients from the Chinese Population

    PubMed Central

    Sharma, Ashok; He, Mingfang; Xue, Jing; Wu, Jianzhong; Dun, Boying; Li, Gang; Wang, Xiaoxiao; Ji, Minghua; She, Jin-Xiong; Tang, Jinhai

    2015-01-01

    Background Inflammation is one of the major hallmarks of cancer. This study was designed to profile a panel of inflammatory mediators in gastric adenocarcinoma (GA) and to identify their potential differences separately in metastatic and non-metastatic patient subgroups. Methods Serum samples from 216 GA patients and 333 healthy controls from China were analyzed for six proteins using the Luminex multiplex assay. Results The serum levels for all the six proteins were significantly elevated in metastatic GA compared to non-metastatic GA. Two acute phase proteins (SAA and CRP) and a CXC chemokine (GRO) were significantly elevated in metastatic GA (p <0.01) but smaller changes were observed in non-metastatic GA compared to healthy controls. OPN is moderately increased in non-metastatic GA (2.05-fold) and more severely elevated in metastatic GA (3.34-fold). Surprisingly, soluble VCAM1 and AGP were significantly lower in both non-metastatic and metastatic GA patients compared to controls. Several individual proteins were shown to possess moderate diagnostic value for non-metastatic GA (AUC = 0.786, 0.833, 0.823 for OPN, sVCAM1 and AGP, respectively) and metastatic GA (AUC = 0.931, 0.720, 0.834 and 0.737 for OPN, sVCAM1, SAA and CRP, respectively). However, protein combinations further improve the diagnostic potential for both non-metastatic GA (best AUC = 0.946) and metastatic GA (best AUC = 0.963). The protein combination with best AUC value for both comparisons is OPN+sVCAM1+AGP+SAA. Conclusions These results suggest that several serum proteins are directly related to the severity of gastric cancer. Overall, stronger associations are observed with metastatic than non-metastatic GA as the protein changes are greater with the metastatic status. A combination of these serum proteins may serve as non-invasive markers to assess the severity status and stage of gastric cancer. PMID:25884401

  8. 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.

  9. Sperm of patients with severe asthenozoospermia show biochemical, molecular and genomic alterations.

    PubMed

    Bonanno, Oriana; Romeo, Giulietta; Asero, Paola; Pezzino, Franca Maria; Castiglione, Roberto; Burrello, Nunziatina; Sidoti, Giuseppe; Frajese, Giovanni Vanni; Vicari, Enzo; D'Agata, Rosario

    2016-12-01

    The multifactorial pathological condition, that is, severe low sperm motility is a frequent cause of infertility. However, mechanisms underlying the development of this condition are not completely understood. Single abnormalities have been reported in sperm of patients with asthenozoospermia. In this study, we characterized, in 22 normozoospermic men and in 37 patients with asthenozoospermia, biochemical, molecular and genomic abnormalities that frequently occur in sperm of patients with asthenozoospermia. We evaluated a panel of sperm biomarkers that may affect the motility and fertilizing ability of sperm of patients with severe asthenozoospermia. Since reactive oxygen species (ROS) production is involved in the pathogenesis of such sperm abnormalities, we determined the association between ROS production and sperm abnormalities. High percentage of patients with severe asthenozoospermia showed increased basal and stimulated ROS production. Moreover, these patients showed increased mitochondrial DNA (mtDNA) copy number but decreased mtDNA integrity and they were associated with elevated ROS levels. Furthermore, mitochondrial membrane potential was also significantly decreased and again associated with high ROS production in these patients. However, the rate of nuclear DNA fragmentation was increased only in less than one-fifth of these patients. An important cohort of these patients showed multiple identical biochemical, molecular and genomic abnormalities, which are typical manifestations of oxidative stress. The most frequent association was found in patients with high ROS levels, increased mtDNA copy number and decreased integrity, and low MMP. A smaller cohort of the aforementioned patients also showed nDNA fragmentation. Therefore, patients with asthezoospermia likely present reduced fertilizing potential because of such composed abnormalities.

  10. Severe protein deficiency and repletion alter body and brain composition and organ weights in infant pigs.

    PubMed

    Pond, W G; Ellis, K J; Mersmann, H J; Heath, J P; Krook, L P; Burrin, D G; Dudley, M A; Sheng, H P

    1996-01-01

    Three-wk-old genetically lean or obese pigs were used in two experiments to determine the changes in body composition, visceral organs and brain in response to severe protein deficiency. In Experiment 1, 16 obese pigs were fed an adequate (A, 21% protein, 3% fat) or a protein-deficient (D, 5% protein, 23% fat) diet for 7 wk. One-half of each group was killed at 7 wk, and the remainder of each group was fed the A diet for an additional 8 wk. At 7 wk, pigs fed D contained a higher percentage of fat than those fed A (P < 0.01); after 8-wk of repletion, body composition of the two groups was similar. Duodenum, jejunum, and ileum of the protein-deficient pigs had severely atrophic villi, submucosal edema, and atrophic muscle layers; after 8 wk of repletion, however, microscopic architecture of the gastrointestinal tract was restored to normal. Absolute cerebrum weight at 7 wk, but not after 8 wk repletion, in the pigs fed D were significantly less than in pigs fed A, indicating reduced brain cellularity after 7 wk of protein restriction, but not after 8 wk repletion. In Experiment 2, genetically obese (O, n = 8) and lean (L, n = 8) pigs consumed the A or D diet ad libitum for 10 wk. L and O pigs responded similarly to protein deficiency; D pigs were fatter than A pigs and plasma constituents, bone mineral content, bone mineral density and most organ weights revealed no interactions between diet and genotype. The pig model system used in these experiments enabled the isolation of protein deficiency from infectious disease, parasites and social environmental stimulation that may confound interpretation of human infant malnutrition experiments. The data suggest that genetically controlled body fatness is not a major determinant in the response of the infant pig to severe protein deficiency.

  11. 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

  12. Severe pre-eclampsia is associated with alterations in cytotrophoblasts of the smooth chorion

    PubMed Central

    Garrido-Gomez, Tamara; Ona, Katherine; Kapidzic, Mirhan; Gormley, Matthew; Simón, Carlos; Genbacev, Olga

    2017-01-01

    Pre-eclampsia (PE), which affects ∼8% of first pregnancies, is associated with faulty placentation. Extravillous cytotrophoblasts (CTBs) fail to differentiate properly, contributing to shallow uterine invasion and deficient spiral artery remodeling. We studied the effects of severe PE (sPE) on the smooth chorion portion of the fetal membranes. The results showed a significant expansion of the CTB layer. The cells displayed enhanced expression of stage-specific antigens that extravillous CTBs normally upregulate as they exit the placenta. Transcriptomics revealed the dysregulated expression of many genes (e.g. placental proteins, markers of oxidative stress). We confirmed an sPE-related increase in production of PAPPA1, which releases IGF1 from its binding protein. IGF1 enhanced proliferation of smooth chorion CTBs, a possible explanation for expansion of this layer, which may partially compensate for the placental deficits. PMID:28232601

  13. Ocular hemodynamics during isometric exercise.

    PubMed

    Kiss, B; Dallinger, S; Polak, K; Findl, O; Eichler, H G; Schmetterer, L

    2001-01-01

    The autoregulatory capacity of the human retina is well documented, but the pressure-flow relationship of the human choroid is still a matter of controversy. Recent data, using laser Doppler flowmetry to measure choroidal blood flow, indicate that the choroid has some autoregulatory potential, whereas most data using other techniques for the assessment of choroidal hemodynamics indicate that the choroidal pressure-flow curve is linear. We used a new laser interferometric technique to characterize choroidal blood flow during isometric exercise. Twenty healthy subjects performed squatting for 6 min during normocapnia and during inhalation of 5% CO2 and 95% air. Ocular fundus pulsation amplitude, flow velocities in the ophthalmic artery, intraocular pressure, and systemic hemodynamics were measured in 2-min intervals. To gain information on choroidal blood flow fundus pulsation amplitude was corrected for changes in flow pulsatility using data from the ophthalmic artery and for changes in pulse rate. Ocular perfusion pressure was calculated from mean arterial pressure and intraocular pressure. The ocular pressure-flow relationship was calculated by sorting data according to ascending ocular perfusion pressure values. In a pilot study in 6 healthy subjects comparable ocular pressure flow relationships were obtained when choroidal blood flow was assessed with the method described above and with laser Doppler flowmetry. In the main study isometric exercise caused a significant increase in mean arterial pressure (56%, P < 0.001), pulse rate (84%, P < 0.001), and intraocular pressure (37%, P 0.004), but decreased fundus pulsation amplitude (-36%, P < 0.001). Significant deviations from baseline choroidal blood flow were observed only at ocular perfusion pressures >69% during normocapnia and 70% during hypercapnia. Our data indicate that during isometric exercise the choroid has a high capacity to keep blood flow constant despite changes in perfusion pressure and that this

  14. Trait Mindfulness, Problem-Gambling Severity, Altered State of Awareness and Urge to Gamble in Poker-Machine Gamblers.

    PubMed

    McKeith, Charles F A; Rock, Adam J; Clark, Gavin I

    2016-09-12

    In Australia, poker-machine gamblers represent a disproportionate number of problem gamblers. To cultivate a greater understanding of the psychological mechanisms involved in poker-machine gambling, a repeated measures cue-reactivity protocol was administered. A community sample of 38 poker-machine gamblers was assessed for problem-gambling severity and trait mindfulness. Participants were also assessed regarding altered state of awareness (ASA) and urge to gamble at baseline, following a neutral cue, and following a gambling cue. Results indicated that: (a) urge to gamble significantly increased from neutral cue to gambling cue, while controlling for baseline urge; (b) cue-reactive ASA did not significantly mediate the relationship between problem-gambling severity and cue-reactive urge (from neutral cue to gambling cue); (c) trait mindfulness was significantly negatively associated with both problem-gambling severity and cue-reactive urge (i.e., from neutral cue to gambling cue, while controlling for baseline urge); and (d) trait mindfulness did not significantly moderate the effect of problem-gambling severity on cue-reactive urge (from neutral cue to gambling cue). This is the first study to demonstrate a negative association between trait mindfulness and cue-reactive urge to gamble in a population of poker-machine gamblers. Thus, this association merits further evaluation both in relation to poker-machine gambling and other gambling modalities.

  15. Hemodynamic coherence and the rationale for monitoring the microcirculation

    PubMed Central

    2015-01-01

    This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such conditions. The article emphasizes that if resuscitation procedures are based on the correction of systemic variables, there must be coherence between the macrocirculation and microcirculation if systemic hemodynamic-driven resuscitation procedures are to be effective in correcting organ perfusion and oxygenation. However, in conditions of inflammation and infection, which often accompany states of shock, vascular regulation and compensatory mechanisms needed to sustain hemodynamic coherence are lost, and the regional circulation and microcirculation remain in shock. We identify four types of microcirculatory alterations underlying the loss of hemodynamic coherence: type 1, heterogeneous microcirculatory flow; type 2, reduced capillary density induced by hemodilution and anemia; type 3, microcirculatory flow reduction caused by vasoconstriction or tamponade; and type 4, tissue edema. These microcirculatory alterations can be observed at the bedside using direct visualization of the sublingual microcirculation with hand-held vital microscopes. Each of these alterations results in oxygen delivery limitation to the tissue cells despite the presence of normalized systemic hemodynamic variables. Based on these concepts, we propose how to optimize the volume of fluid to maximize the oxygen-carrying capacity of the microcirculation to transport oxygen to the tissues. PMID:26729241

  16. Growth and hemodynamics after early embryonic aortic arch occlusion.

    PubMed

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

    2015-08-01

    The majority of severe clinically significant forms of congenital heart disease (CHD) are 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. Here, we combine computational fluid dynamics (CFD) simulations with in vivo experiments to test how individual pharyngeal arch artery hemodynamics alter as a result of local interventions obstructing 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 h. 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

  17. 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

  18. 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

  19. 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

  20. Truncated Peroxisome Proliferator-Activated Receptor-γ Coactivator 1α Splice Variant Is Severely Altered in Huntington's Disease

    PubMed Central

    Johri, Ashu; Starkov, Anatoly A.; Chandra, Abhishek; Hennessey, Thomas; Sharma, Abhijeet; Orobello, Sara; Squitieri, Ferdinando; Yang, Lichuan; Beal, M. Flint

    2011-01-01

    Background Reduced peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) gene expression has been observed in striatal cell lines, transgenic mouse models of Huntington's disease (HD), and brain tissue from HD patients. As this protein is a key transcription regulator of the expression of many mitochondrial proteins, these observations strongly support the role of aberrant mitochondrial function in the pathogenesis of HD. The PGC1α protein undergoes posttranslational modifications that affect its transcriptional activity. The N-truncated splice variant of PGC1α (NT-PGC1α) is produced in tissues, but the role of truncated splice variants of PGC1α in HD and in the regulation of mitochondrial gene expression has not been elucidated. Objective To examine the expression and modulation of expression of NT-PGC1α levels in HD. Methods and Results We found that the NT-PGC1α protein, a splice variant of ∼38 kDa, but not full-length PGC1α is severely and consistently altered in human HD brain, human HD myoblasts, mouse HD models, and HD striatal cells. NT-PGC1α levels were significantly upregulated in HD cells and mouse brown fat by physiologically relevant stimuli that are known to upregulate PGC1α gene expression. This resulted in an increase in mitochondrial gene expression and cytochrome c content. Conclusion Our data suggest that NT-PGC1α is an important component of the PGC1α transcriptional network, which plays a significant role in the pathogenesis of HD. Copyright © 2011 S. Karger AG, Basel PMID:21757867

  1. 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.

  2. Hemodynamic Consequences of Malignant Ascites in Epithelial Ovarian Cancer Surgery∗

    PubMed Central

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

    2015-01-01

    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. 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…

  4. [Hemodynamic study of the elderly subject. Indications, risks and value].

    PubMed

    Ohayon, J; Colle, J P; Besse, P

    1985-04-30

    The authors record all the hemodynamic evaluations realised on aged population above severity years during two years (549 patients) representing ten per cent of the whole investigations in an hemodynamic department. The greater part of the indications were severe coronaritis resistant to medical treatment (54 percent) with unstable angina or steady state angina, and valvulopathy (37 percent) with prevalence of symptomatic aortic stenosis. The catheterization incidents and accidents do not appear more owing to the high risk pathology and to the taken precautions. The lethal accident frequency is three point five per thousand little above the frequency in a general catheterized population (two per thousand). Seldinger difficulties are easily got over by using axillary passage in case of need. The surgical interest is underlined by the fact that sixty six percent of the investigated patients will be operated. The hemodynamic evaluation in aged population between 70 and 80 years is realizable in good conditions with little risk increase when it's necessary.

  5. Hemodynamic forces in a model left ventricle

    NASA Astrophysics Data System (ADS)

    Domenichini, Federico; Pedrizzetti, Gianni

    2016-12-01

    Intraventricular pressure gradients were clinically demonstrated to represent one useful indicator of the left ventricle (LV) function during the development of heart failure. We analyze the fluid dynamics inside a model LV to improve the understanding of the development of hemodynamic forces (i.e., mean pressure gradient) in normal conditions and their modification in the presence of alterations of LV tissue motion. To this aim, the problem is solved numerically and the global force exchanged between blood flow and LV boundaries is computed by volume integration. We also introduce a simplified analytical model, based on global conservation laws, to estimate hemodynamic forces from the knowledge of LV tissue information commonly available in cardiac imaging. Numerical results show that the normal intraventricular gradients feature a deep brief suction at early diastolic filling and a persistent thrust during systolic ejection. In presence of abnormalities of the wall motion, the loss of time synchrony is more relevant than the loss of spatial uniformity in modifying the normal pressure gradient spatiotemporal pattern. The main findings are reproduced in the integral model, which represents a possible easy approach for integrating fluid dynamics evaluations in the clinical examination.

  6. 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

    2015-09-08

    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.

  7. 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

  8. Hemodynamic response to the upright posture.

    PubMed

    Smith, J J; Porth, C M; Erickson, M

    1994-05-01

    The authors' objective was to review previous studies of immediate (first 30 seconds) and stabilized (30 seconds to 20 minutes) hemodynamic responses of healthy adults to the head-up posture, with particular reference to alteration of such responses in the elderly and the usefulness of such data in the diagnosis of orthostatic hypotension. The immediate response in healthy young adults is characterized by a prompt rise in heart rate, which peaks at about 8 to 15 seconds and then tapers; the arterial pressure and total vascular resistance decrease sharply at 5 to 10 seconds, followed by a rapid rebound and overshoot. Over the first 30 seconds there is a steady parallel decline of thoracic blood volume and stroke volume; there is also an initial surge of cardiac output followed by a steady decrease. During the stabilized response (30 seconds to 20 minutes), the hemodynamic variables are relatively steady, showing average increases in heart rate of about 15 to 30%, in diastolic pressure of 10 to 15%, and in total vascular resistance of 30 to 40%; during the 5th to 20th minutes there are also decreases in thoracic blood volume averaging about 25 to 30%, in cardiac output 15 to 30%, and in pulse pressure about 5 to 10%. It is evident that in normal human subjects, assumption of the upright posture results in profound hemodynamic changes, most of them occurring during the first 30 seconds. In elderly subjects (aged 60-69 years), there are, in the upright posture, lesser increments of heart rate and diastolic pressure, but no significant differences from younger age groups in the response of thoracic blood volume, cardiac output or total vascular resistance. However, beginning at about age 75, there is an increasing incidence of orthostatic hypotension, which averages about 14 to 20% at age 75 and older. The tendency toward orthostatic hypotension in the elderly is due (1) to the structural and functional changes in the circulation itself, (2) to a decline in autonomic

  9. Expression, topography, and function of integrin receptors are severely altered in keratinocytes from involved and uninvolved psoriatic skin.

    PubMed Central

    Pellegrini, G; De Luca, M; Orecchia, G; Balzac, F; Cremona, O; Savoia, P; Cancedda, R; Marchisio, P C

    1992-01-01

    Psoriasis is a hyperproliferative cutaneous disease of unknown etiology and etiopathogenesis. Alteration of keratinocyte adhesiveness to basal lamina has been proposed as the initial disturbance leading to poorly controlled proliferation. Keratinocyte adhesion to basal lamina and lateral interactions among basal epidermal cells are mediated, besides other molecules, by integrin receptors that are segregated to discrete membrane domains. In this paper, the expression and function of integrins in psoriatic keratinocytes were examined, both in vivo and in vitro. We found that: (a) in psoriatic keratinocytes the integrin heterodimers alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 4 have lost their polarized distribution on the plasma membrane; (b) the role of these integrins in mediating keratinocyte adhesion in vitro is altered; (c) psoriatic keratinocytes form focal contacts containing both beta 1 and beta 4 integrins. In normal adult keratinocytes the alpha 5 beta 1 fibronectin receptor is poorly expressed and diffusely distributed on the basal keratinocyte plasma membrane and is not organized in defined adhesive structures. In contrast, psoriatic keratinocytes show a clear fibronectin receptor staining in vivo, and organize alpha 5 beta 1 in typical focal contacts in vitro without any obvious increase of its expression and synthesis. These multiple alterations of integrins are also present in uninvolved keratinocytes from psoriatic patients, suggesting a key role for altered integrin-mediated adhesion in the pathogenesis of this disease. Images PMID:1534817

  10. Expression, topography, and function of integrin receptors are severely altered in keratinocytes from involved and uninvolved psoriatic skin.

    PubMed

    Pellegrini, G; De Luca, M; Orecchia, G; Balzac, F; Cremona, O; Savoia, P; Cancedda, R; Marchisio, P C

    1992-06-01

    Psoriasis is a hyperproliferative cutaneous disease of unknown etiology and etiopathogenesis. Alteration of keratinocyte adhesiveness to basal lamina has been proposed as the initial disturbance leading to poorly controlled proliferation. Keratinocyte adhesion to basal lamina and lateral interactions among basal epidermal cells are mediated, besides other molecules, by integrin receptors that are segregated to discrete membrane domains. In this paper, the expression and function of integrins in psoriatic keratinocytes were examined, both in vivo and in vitro. We found that: (a) in psoriatic keratinocytes the integrin heterodimers alpha 2 beta 1, alpha 3 beta 1, and alpha 6 beta 4 have lost their polarized distribution on the plasma membrane; (b) the role of these integrins in mediating keratinocyte adhesion in vitro is altered; (c) psoriatic keratinocytes form focal contacts containing both beta 1 and beta 4 integrins. In normal adult keratinocytes the alpha 5 beta 1 fibronectin receptor is poorly expressed and diffusely distributed on the basal keratinocyte plasma membrane and is not organized in defined adhesive structures. In contrast, psoriatic keratinocytes show a clear fibronectin receptor staining in vivo, and organize alpha 5 beta 1 in typical focal contacts in vitro without any obvious increase of its expression and synthesis. These multiple alterations of integrins are also present in uninvolved keratinocytes from psoriatic patients, suggesting a key role for altered integrin-mediated adhesion in the pathogenesis of this disease.

  11. 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.

  12. Altered Cognitive Control Activations after Moderate-to-Severe Traumatic Brain Injury and Their Relationship to Injury Severity and Everyday-Life Function.

    PubMed

    Olsen, Alexander; Brunner, Jan Ferenc; Indredavik Evensen, Kari Anne; Finnanger, Torun Gangaune; Vik, Anne; Skandsen, Toril; Landrø, Nils Inge; Håberg, Asta Kristine

    2015-08-01

    This study investigated how the neuronal underpinnings of both adaptive and stable cognitive control processes are affected by traumatic brain injury (TBI). Functional magnetic resonance imaging (fMRI) was undertaken in 62 survivors of moderate-to-severe TBI (>1 year after injury) and 68 healthy controls during performance of a continuous performance test adapted for use in a mixed block- and event-related design. Survivors of TBI demonstrated increased reliance on adaptive task control processes within an a priori core region for cognitive control in the medial frontal cortex. TBI survivors also had increased activations related to time-on-task effects during stable task-set maintenance in right inferior parietal and prefrontal cortices. Increased brain activations in TBI survivors had a dose-dependent linear positive relationship to injury severity and were negatively correlated with self-reported cognitive control problems in everyday-life situations. Results were adjusted for age, education, and fMRI task performance. In conclusion, evidence was provided that the neural underpinnings of adaptive and stable control processes are differently affected by TBI. Moreover, it was demonstrated that increased brain activations typically observed in survivors of TBI might represent injury-specific compensatory adaptations also utilized in everyday-life situations.

  13. Altered Cognitive Control Activations after Moderate-to-Severe Traumatic Brain Injury and Their Relationship to Injury Severity and Everyday-Life Function

    PubMed Central

    Olsen, Alexander; Brunner, Jan Ferenc; Indredavik Evensen, Kari Anne; Finnanger, Torun Gangaune; Vik, Anne; Skandsen, Toril; Landrø, Nils Inge; Håberg, Asta Kristine

    2015-01-01

    This study investigated how the neuronal underpinnings of both adaptive and stable cognitive control processes are affected by traumatic brain injury (TBI). Functional magnetic resonance imaging (fMRI) was undertaken in 62 survivors of moderate-to-severe TBI (>1 year after injury) and 68 healthy controls during performance of a continuous performance test adapted for use in a mixed block- and event-related design. Survivors of TBI demonstrated increased reliance on adaptive task control processes within an a priori core region for cognitive control in the medial frontal cortex. TBI survivors also had increased activations related to time-on-task effects during stable task-set maintenance in right inferior parietal and prefrontal cortices. Increased brain activations in TBI survivors had a dose-dependent linear positive relationship to injury severity and were negatively correlated with self-reported cognitive control problems in everyday-life situations. Results were adjusted for age, education, and fMRI task performance. In conclusion, evidence was provided that the neural underpinnings of adaptive and stable control processes are differently affected by TBI. Moreover, it was demonstrated that increased brain activations typically observed in survivors of TBI might represent injury-specific compensatory adaptations also utilized in everyday-life situations. PMID:24557637

  14. Hemodynamic aspects of Alzheimer's disease.

    PubMed

    Nagata, Ken; Sato, Mika; Satoh, Yuichi; Watahiki, Yasuhito; Kondoh, Yasushi; Sugawara, Maki; Box, Georgia; Wright, David; Leung, Sumie; Yuya, Hiromichi; Shimosegawa, Eku

    2002-11-01

    Neuroradiological functional imaging techniques demonstrate the patterns of hypoperfusion and hypometabolism that are thought to be useful in the differential diagnosis of Alzheimer's disease (AD) from other dementing disorders. Besides the distribution patterns of perfusion or energy metabolism, vascular transit time (VTT), vascular reactivity (VR), and oxygen extraction fraction (OEF), which can be measured with positron emission tomography (PET), provide hemodynamic aspects of brain pathophysiology. In order to evaluate the hemodynamic features of AD, PET studies were carried out in 20 patients with probable AD and 20 patients with vascular dementia (VaD). The PET findings were not included in their diagnostic process of AD. Using oxygen-15-labeled compounds, cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO(2)), OEF, cerebral blood volume, and VTT were measured quantitatively during resting state. To evaluate VR, CBF was also measured during CO(2) inhalation. There was a significant increase in OEF in and around the parietotemporal cortices, but both VTT and VR were well preserved in patients with AD. By contrast, VR was markedly depressed and VTT was mildly prolonged in patients with VaD. Thus, from the hemodynamic point of view, the preservation of vascular reserve may be a distinct difference between AD and VaD. Furthermore, this indicates a hemodynamic integrity of the vasculature in the level of arterioles in AD.

  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. Assessment of Conjunctival Microvascular Hemodynamics in Stages of Diabetic Microvasculopathy

    PubMed Central

    Khansari, Maziyar M.; Wanek, Justin; Tan, Michael; Joslin, Charlotte E.; Kresovich, Jacob K.; Camardo, Nicole; Blair, Norman P.; Shahidi, Mahnaz

    2017-01-01

    Diabetes impairs the microcirculation and function of various vital tissues throughout the body. The conjunctival microcirculation can be non-invasively imaged and thus enables assessment of microvascular hemodynamics. In this study, alterations in conjunctival microvascular hemodynamics were quantitatively assessed at stages of increasing diabetic microvasculopathy based on diabetic retinopathy (DR). Subjects were categorized into non-diabetic control (C, N = 34), no clinically visible DR (NDR, N = 47), non-proliferative DR (NPDR, N = 45), and proliferative DR (PDR, N = 35). Conjunctival hemodynamic descriptors, namely vessel diameter (D), blood velocity (V), blood flow (Q), wall shear rate (WSR), and wall shear stress (WSS) were measured in arterioles and venules, and compared between DR and C subjects using generalized linear mixed models. In arterioles, V, WSR, and WSS were lower in NDR (P ≤ 0.01). V was lower in NDR than NPDR and PDR subjects (P ≤ 0.02). In venules, D was higher in NDR and NPDR (P ≤ 0.03), while V was lower in PDR (P = 0.04). Venular V and Q were higher in NPDR than PDR subjects (P ≤ 0.04). WSR and WSS were lower in all stages of DR (P ≤ 0.05), suggestive of the potential of WSS as a marker of diabetic microvasculopathy. Quantitative assessment of conjunctival hemodynamics can potentially be useful for evaluation of diabetic microvasculopathy. PMID:28387229

  17. Aortic hemodynamics and white matter hyperintensities in normotensive postmenopausal women.

    PubMed

    Barnes, Jill N; Harvey, Ronée E; Zuk, Samantha M; Lundt, Emily S; Lesnick, Timothy G; Gunter, Jeffrey L; Senjem, Matthew L; Shuster, Lynne T; Miller, Virginia M; Jack, Clifford R; Joyner, Michael J; Kantarci, Kejal

    2017-04-07

    Hypertension is associated with development of white matter hyperintensities (WMH) in the brain, which are risk factors for mild cognitive impairment. Hormonal shifts at menopause alter vascular function putting women at risk for both hypertension and WMH. Elevations in aortic hemodynamics precede the appearance of clinically defined hypertension but the relationship of aortic hemodynamics to development of WMH in women is not known. Therefore, this study aimed to characterize aortic hemodynamics in relationship to WMH in postmenopausal women. Aortic systolic and diastolic blood pressure (BP), aortic augmentation index (Alx) and aortic round trip travel time (Aortic T R) by tonometry were examined in 53 postmenopausal women (age 60 ± 2 years). WMH was calculated from fluid-attenuated inversion recovery MRI using a semi-automated segmentation algorithm. WMH as a fraction of total white matter volume positively associated with aortic systolic BP (regression coefficient = 0.018; p = 0.04) after adjusting for age. In addition, WMH fraction was positively associated with AIx (0.025; p = 0.04), and inversely associated with Aortic T R (-0.015; p = 0.04) after adjusting for age. Our results suggest that assessing aortic hemodynamics may identify individuals at risk for accelerated development of WMH and guide early treatment to reduce WMH burden and cognitive impairment in the future.

  18. 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.

  19. Altering embryonic cardiac dynamics with optical pacing.

    PubMed

    Peterson, L M; McPheeters, M; Barwick, L; Gu, S; Rollins, A M; Jenkins, M W

    2012-01-01

    Several studies have shown that altering blood flow early in development leads to congenital heart defects. In these studies the perturbations to hemodynamics were very gross manipulations (vessel ligation, conotruncal banding, etc.) that would be inappropriate for probing the delicate mechanisms responsible for mechanically-transduced signaling. Also, these perturbations lacked feedback from a monitoring system to determine the exact degree of alteration and the location of its effect. Here, we employed optical pacing (OP) to alter the heart rate in quail embryos and optical coherence tomography (OCT) to measure the resultant shear forces on the endocardium. OP is a new technique utilizing pulsed 1.851 µm infrared laser light to noninvasively capture the heart rate to the pulse frequency of the laser without the use of exogenous agents. To measure shear stress on the endocardium, we extended our previous OCT algorithms to enable the production of 4-D shear maps. 4-D shear maps allowed observation of the spatial and temporal distribution of shear stress. Employing both OCT and OP, we were able to develop perturbation protocols that increase regurgitant flow and greatly modify the oscillatory shear index (OSI) in a region of the heart tube where future valves will develop. Regurgitant flow has been linked with valve development and precise perturbations may allow one to determine the role of hemodynamics in valvulogenesis.

  20. 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.

  1. 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.

  2. Remodeling of blood vessels: responses of diameter and wall thickness to hemodynamic and metabolic stimuli.

    PubMed

    Pries, Axel R; Reglin, Bettina; Secomb, Timothy W

    2005-10-01

    Vascular functions, including tissue perfusion and peripheral resistance, reflect continuous structural adaptation (remodeling) of blood vessels in response to several stimuli. Here, a theoretical model is presented that relates the structural and functional properties of microvascular networks to the adaptive responses of individual segments to hemodynamic and metabolic stimuli. All vessels are assumed to respond, according to a common set of adaptation rules, to changes in wall shear stress, circumferential wall stress, and tissue metabolic status (indicated by partial pressure of oxygen). An increase in vessel diameter with increasing wall shear stress and an increase in wall mass with increased circumferential stress are needed to ensure stable vascular adaptation. The model allows quantitative predictions of the effects of changes in systemic hemodynamic conditions or local adaptation characteristics on vessel structure and on peripheral resistance. Predicted effects of driving pressure on the ratio of wall thickness to vessel diameter are consistent with experimental observations. In addition, peripheral resistance increases by approximately 65% for an increase in driving pressure from 50 to 150 mm Hg. Peripheral resistance is predicted to be markedly increased in response to a decrease in vascular sensitivity to wall shear stress, and to be decreased in response to increased tissue metabolic demand. This theoretical approach provides a framework for integrating available information on structural remodeling in the vascular system and predicting responses to changing conditions or altered vascular reactivity, as may occur in hypertension.

  3. [Hemorheology, hemodynamics and microcirculation. 1].

    PubMed

    Larcan, A; Stoltz, J F

    1989-01-01

    The microcirculation constitutes an ubiquitous vascular network presenting a mesh pattern, and comprising different types of vessels, arterioles, small veins, capillaries, arteriovenous shunts or similar structures, and lymphatics. Many dimensions have to be recognized, or simply mentioned, if one is to understand the hemodynamic and hemorheological particulars of this territory, which differ, in many aspects, from those specific to the macrocirculation (number and length of the vessels, diameter and cross section, intercapillary distance, geometric characteristics, intravascular pressure, pressure gradient, pressure-volume relationship, flow rate, mean velocity of plasma and RBC, velocity profile, local hematocrit, in situ viscosity, kinematic viscosity, wall shearing conditions, local oxygen transport, aggregation and deformability of RBC, leukocyte properties, etc.). The flow rate in capillary tubes and capillary vessels of the living organism varies with many factors, such as proximal hemodynamics, hemorheological characteristics of blood (fibrinogen, macro- and micro-hematocrit), some known effects (Farheus, Farheus Lindqvist), local diameter, the plasma layer which plays the role of the limiting layer, the endothelial film, the wall effect, and so forth. Models of the circulation have been propounded, none of which takes into account the whole of these phenomena due to their great complexity. Hemodynamic and hemorheological interactions provide for a better understanding of certain concepts, such as vascular resistance, hindrance, capacitance, local flow rates, real capillary opening and closing, development of two-directional functional shunts, autoregulation, pressure-volume relationship, critical closing pressure, circulatory current slowing effect, sequelae of intravascular aggregation of formed blood elements.

  4. Neurodegeneration severity can be predicted from early microglia alterations monitored in vivo in a mouse model of chronic glaucoma

    PubMed Central

    Bosco, Alejandra; Romero, Cesar O.; Breen, Kevin T.; Chagovetz, Alexis A.; Steele, Michael R.; Ambati, Balamurali K.; Vetter, Monica L.

    2015-01-01

    ABSTRACT Microglia serve key homeostatic roles, and respond to neuronal perturbation and decline with a high spatiotemporal resolution. The course of all chronic CNS pathologies is thus paralleled by local microgliosis and microglia activation, which begin at early stages of the disease. However, the possibility of using live monitoring of microglia during early disease progression to predict the severity of neurodegeneration has not been explored. Because the retina allows live tracking of fluorescent microglia in their intact niche, here we investigated their early changes in relation to later optic nerve neurodegeneration. To achieve this, we used the DBA/2J mouse model of inherited glaucoma, which develops progressive retinal ganglion cell degeneration of variable severity during aging, and represents a useful model to study pathogenic mechanisms of retinal ganglion cell decline that are similar to those in human glaucoma. We imaged CX3CR1+/GFP microglial cells in vivo at ages ranging from 1 to 5 months by confocal scanning laser ophthalmoscopy (cSLO) and quantified cell density and morphological activation. We detected early microgliosis at the optic nerve head (ONH), where axonopathy first manifests, and could track attenuation of this microgliosis induced by minocycline. We also observed heterogeneous and dynamic patterns of early microglia activation in the retina. When the same animals were aged and analyzed for the severity of optic nerve pathology at 10 months of age, we found a strong correlation with the levels of ONH microgliosis at 3 to 4 months. Our findings indicate that live imaging and monitoring the time course and levels of early retinal microgliosis and microglia activation in glaucoma could serve as indicators of future neurodegeneration severity. PMID:25755083

  5. Cerebral hemodynamics and endothelial function in patients with Fabry disease

    PubMed Central

    2013-01-01

    Background Cerebral vasculopathy have been described in Fabry disease, in which altered cerebral blood flow, vascular remodelling or impairment of endothelial function could be involved. Our study aims to evaluate these three possibilities in a group of Fabry patients, and compare it to healthy controls. Methods Cerebral hemodynamics, vascular remodelling and systemic endothelial function were investigated in 10 Fabry patients and compared to data from 17 healthy controls. Transcranial Doppler was used to study blood flow velocity of intracranial arteries and cerebral vasomotor reactivity. For the study of vascular remodelling and endothelial function, intima-media thickness of common carotid arteries, flow-mediated dilation in brachial artery and serum levels of soluble VCAM-1, TNF-α, high-sensitive CRP and IL-6 were measured. Differences between groups were evaluated using appropriate tests. Results No relevant differences were observed in cerebral hemodynamic parameters, intima-media thickness or flow-mediated dilation. There was a trend for low serum levels of IL-6 and high serum levels of TNF-α and high-sensitive CRP in Fabry patients; plasma concentrations of soluble VCAM-1 were significantly higher in Fabry disease patients than in healthy volunteers (p = 0.02). Conclusions In our sample, we did not find relevant alterations of cerebral hemodynamics in Fabry disease patients. Increased levels of plasmatic endothelial biomarkers seem to be the most important feature indicative of possible vascular dysfunction in Fabry disease patients. PMID:24207059

  6. 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.

  7. Systemic hemodynamics in advanced cirrhosis: Concerns during perioperative period of liver transplantation

    PubMed Central

    Hori, Tomohide; Ogura, Yasuhiro; Onishi, Yasuharu; Kamei, Hideya; Kurata, Nobuhiko; Kainuma, Motoshi; Takahashi, Hideo; Suzuki, Shogo; Ichikawa, Takashi; Mizuno, Shoko; Aoyama, Tadashi; Ishida, Yuki; Hirai, Takahiro; Hayashi, Tomoko; Hasegawa, Kazuko; Takeichi, Hiromu; Ota, Atsunobu; Kodera, Yasuhiro; Sugimoto, Hiroyuki; Iida, Taku; Yagi, Shintaro; Taniguchi, Kentaro; Uemoto, Shinji

    2016-01-01

    Advanced liver cirrhosis is usually accompanied by portal hypertension. Long-term portal hypertension results in various vascular alterations. The systemic hemodynamic state in patients with cirrhosis is termed a hyperdynamic state. This peculiar hemodynamic state is characterized by an expanded blood volume, high cardiac output, and low total peripheral resistance. Vascular alterations do not disappear even long after liver transplantation (LT), and recipients with cirrhosis exhibit a persistent systemic hyperdynamic state even after LT. Stability of optimal systemic hemodynamics is indispensable for adequate portal venous flow (PVF) and successful LT, and reliable parameters for optimal systemic hemodynamics and adequate PVF are required. Even a subtle disorder in systemic hemodynamics is precisely indicated by the balance between cardiac output and blood volume. The indocyanine green (ICG) kinetics reflect the patient’s functional hepatocytes and effective PVF, and PVF is a major determinant of the ICG elimination constant (kICG) in the well-preserved allograft. The kICG value is useful to set the optimal PVF during living-donor LT and to evaluate adequate PVF after LT. Perioperative management has a large influence on the postoperative course and outcome; therefore, key points and unexpected pitfalls for intensive management are herein summarized. Transplant physicians should fully understand the peculiar systemic hemodynamic behavior in LT recipients with cirrhosis and recognize the critical importance of PVF after LT. PMID:27660671

  8. Forest fuel reduction alters fire severity and long-term carbon storage in three Pacific Northwest ecosystems.

    PubMed

    Mitchell, Stephen R; Harmon, Mark E; O'Connell, Kari E B

    2009-04-01

    Two forest management objectives being debated in the context of federally managed landscapes in the U.S. Pacific Northwest involve a perceived trade-off between fire restoration and carbon sequestration. The former strategy would reduce fuel (and therefore C) that has accumulated through a century of fire suppression and exclusion which has led to extreme fire risk in some areas. The latter strategy would manage forests for enhanced C sequestration as a method of reducing atmospheric CO2 and associated threats from global climate change. We explored the trade-off between these two strategies by employing a forest ecosystem simulation model, STANDCARB, to examine the effects of fuel reduction on fire severity and the resulting long-term C dynamics among three Pacific Northwest ecosystems: the east Cascades ponderosa pine forests, the west Cascades western hemlock-Douglas-fir forests, and the Coast Range western hemlock-Sitka spruce forests. Our simulations indicate that fuel reduction treatments in these ecosystems consistently reduced fire severity. However, reducing the fraction by which C is lost in a wildfire requires the removal of a much greater amount of C, since most of the C stored in forest biomass (stem wood, branches, coarse woody debris) remains unconsumed even by high-severity wildfires. For this reason, all of the fuel reduction treatments simulated for the west Cascades and Coast Range ecosystems as well as most of the treatments simulated for the east Cascades resulted in a reduced mean stand C storage. One suggested method of compensating for such losses in C storage is to utilize C harvested in fuel reduction treatments as biofuels. Our analysis indicates that this will not be an effective strategy in the west Cascades and Coast Range over the next 100 years. We suggest that forest management plans aimed solely at ameliorating increases in atmospheric CO2 should forgo fuel reduction treatments in these ecosystems, with the possible exception of

  9. Infection with Chlamydia trachomatis alters the tyrosine phosphorylation and/or localization of several host cell proteins including cortactin.

    PubMed Central

    Fawaz, F S; van Ooij, C; Homola, E; Mutka, S C; Engel, J N

    1997-01-01

    Infection of epithelial cells by two biovars of Chlamydia trachomatis results in the tyrosine phosphorylation of several host proteins. The most prominent change in host protein tyrosine phosphorylation involves a complex of proteins with molecular masses of 75 to 85 kDa (pp75/85) and 100 kDa (pp100). The C. trachomatis-induced tyrosine phosphorylation of pp75/85 and pp100 is observed in several cell lines, including epithelial cells, fibroblasts, and macrophages. Subcellular fractionation and detergent solubility properties of pp75/85 are consistent with its association with the cytoskeleton. Phosphoamino acid analysis demonstrates that the pp75/85 complex is phosphorylated on both tyrosine and serine residues. Immunofluorescence studies of chlamydia-infected cells by using fluorescein isothiocyanate-phalloidin and antibodies to phosphotyrosine and cortactin demonstrate that tyrosine-phosphorylated proteins, as well as cortactin, are localized to the chlamydial vacuole and that this process is facilitated by actin. PMID:9393830

  10. Skeletal muscle myotubes of the severely obese exhibit altered ubiquitin-proteasome and autophagic/lysosomal proteolytic flux

    PubMed Central

    Bollinger, Lance M.; Powell, Jonathan J. S.; Houmard, Joseph A.; Witczak, Carol A.; Brault, Jeffrey J.

    2015-01-01

    Objective Whole-body protein metabolism is dysregulated with obesity. Our goal was to determine if activity and expression of major protein degradation pathways are compromised specifically in human skeletal muscle with obesity. Methods We utilized primary Human Skeletal Muscle cell (HSkM) cultures since cellular mechanisms can be studied absent of hormones and contractile activity that could independently influence metabolism. HSkM from 10 lean (BMI ≤ 26.0 kg/m2) and 8 severely obese (BMI ≥ 39.0) women were examined basally and when stimulated to atrophy (serum and amino acid starvation). Results HSkM from obese donors had a lower proportion of type I myosin heavy chain and slower flux through the autophagic/lysosomal pathway. During starvation, flux through the ubiquitin-proteasome system diverged according to obesity status, with a decrease in the lean and an increase in HSkM from obese subjects. HSkMC from the obese also displayed elevated proteasome activity despite no difference in proteasome content. Atrophy-related gene expression and myotube area were similar in myotubes derived from lean and obese individuals under basal and starved conditions. Conclusions Our data indicate that muscle cells of the lean and severely obese have innate differences in management of protein degradation, which may explain their metabolic differences. PMID:26010327

  11. 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

  12. [Pulmonary hemodynamics and hemostasis in rabbits exposed to high altitude].

    PubMed

    Almerekova, A A; Tartakovskiĭ, V N; Isakova, Zh T

    1993-01-01

    Pulmonary hemodynamics, homeostasis and red blood parameters were studied in 77 rabbits in the mountains of the Tien Shan (3200 m above sea-level). Exposure of animals in alpine environment gave rise to pulmonary hypertension, polycythemia, alterations of homeostasis by the pattern of hyper- and hypocoagulation syndrome. On certain stages of adaptation products of paracoagulation were observed in blood as well as intravascular aggregation of formed elements, increased sensitivity of blood plates to platelet activation, increased fibrinolysis. Given existing hypothesis about involvement of changes in homeostasis and red blood in the pathogenesis of altitude pulmonary hypertension, the coefficients of paired linear correlation between indices of pulmonary hemodynamics and blood have been calculated. These coefficients are valid only for low values of the ratio.

  13. Clinical relevance of fetal hemodynamic monitoring: Perinatal implications.

    PubMed

    Pruetz, Jay D; Votava-Smith, Jodie; Miller, David A

    2015-08-01

    Comprehensive assessment of fetal wellbeing involves monitoring of fetal growth, placental function, central venous pressure, and cardiac function. Ultrasound evaluation of the fetus using 2D, color Doppler, and pulse-wave Doppler techniques form the foundation of antenatal diagnosis of structural anomalies, rhythm abnormalities and altered fetal circulation. Accurate and timely prenatal identification of the fetus at risk is critical for appropriate parental counseling, antenatal diagnostic testing, consideration for fetal intervention, perinatal planning, and coordination of postnatal care delivery. Fetal hemodynamic monitoring and serial assessment are vital to ensuring fetal wellbeing, particularly in the setting of complex congenital anomalies. A complete hemodynamic evaluation of the fetus gives important information on the likelihood of a smooth postnatal transition and contributes to ensuring the best possible outcome for the neonate.

  14. Cerebral Hemodynamics and Cognitive Function in Cirrhotic Patients with Hepatic Encephalopathy

    PubMed Central

    Zhou, Yuqing; Dong, Qian; Zhang, Rong; Zhou, Shunfeng; Li, Linqiang; Cheng, Keran; Kong, Rui; Yu, Qiang; Xu, Shizan; Li, Jingjing; Li, Sainan; Feng, Jiao; Wu, Liwei; Liu, Tong; Lu, Xiya; Xia, Yujing

    2016-01-01

    Aims. To investigate cerebral hemodynamics in cirrhotic patients with HE and to observe effects of treatment in cerebral hemodynamics and correlations among ammonia, cerebral hemodynamics, and cognitive function. Methods. There were four groups: healthy controls (group 1), cirrhosis without HE (group 2), cirrhosis with MHE (group 3), and cirrhosis with OHE (group 4). Ammonia and cerebral hemodynamics (by TCD) were assessed. Patients in group 3 were subsequently randomized to two subgroups: the control (group A) and the treated (group B, treated with lactulose for two months), and they were retested for ammonia and TCD after treatment. Results. Ammonia, Vm, Vd, PI, and RI were statistically different before treatment, and ammonia, PI, and RI levels paralleled the severity of HE (P < 0.05). In group B, Vd increased and ammonia, PI, and RI declined following treatment (P < 0.05), while there were no differences in group A (P > 0.05). Correlations were found between ammonia and Vd, PI, RI, NCT-A, and DST and also found between Vd, PI, RI, and NCT-A and DST (P < 0.05). Conclusions. This study revealed that cerebral hemodynamics were related to the severity of HE and cerebral autoregulation was impaired. There were tight correlations among ammonia, cerebral hemodynamics, and cognitive function, and, following treatment, cerebral hemodynamics improved. PMID:28096811

  15. Hemodynamic Characterization of Peripheral Arterio-venous Malformations.

    PubMed

    Frey, Sabrina; Haine, A; Kammer, R; von Tengg-Kobligk, H; Obrist, D; Baumgartner, I

    2017-03-21

    Peripheral arterio-venous malformations (pAVMs) are congenital vascular anomalies that require treatment, due to their severe clinical consequences. The complexity of lesions often leads to misdiagnosis and ill-planned treatments. To improve disease management, we developed a computational model to quantify the hemodynamic effects of key angioarchitectural features of pAVMs. Hemodynamic results were used to predict the transport of contrast agent (CA), which allowed us to compare our findings to digital subtraction angiography (DSA) recordings of patients. The model is based on typical pAVM morphologies and a generic vessel network that represents realistic vascular feeding and draining components related to lesions. A lumped-parameter description of the vessel network was employed to compute blood pressure and flow rates. CA-transport was determined by coupling the model to a 1D advection-diffusion equation. Results show that the extent of hemodynamic effects of pAVMs, such as arterial steal and venous hypertension, strongly depends on the lesion type and its vascular architecture. Dimensions of shunting vessels strongly influence hemodynamic parameters. Our results underline the importance of the dynamics of CA-transport in diagnostic DSA images. In this context, we identified a set of temporal CA-transport parameters, which are indicative of the presence and specific morphology of pAVMs.

  16. Amphotericin B severely affects expression and activity of the endothelial constitutive nitric oxide synthase involving altered mRNA stability

    PubMed Central

    Suschek, Christoph Viktor; Bonmann, Eckhard; Kleinert, Hartmut; Wenzel, Michael; Mahotka, Csaba; Kolb, Hubert; Förstermann, Ulrich; Gerharz, Claus-Dieter; Kolb-Bachofen, Victoria

    2000-01-01

    The therapeutic use of the antifungal drug amphotericin B (AmB) is limited due to severe side effects like glomerular vasoconstriction and risk of renal failure during AmB administration. As nitric oxide (NO) has substantial functions in renal autoregulation, we have determined the effects of AmB on endothelial constitutive NO synthase (ecNOS) expression and activity in human and rat endothelial cell cultures.AmB used at concentrations of 0.6 to 1.25 μg ml−1 led to increases in ecNOS mRNA and protein expression as well as NO production. This was the result of an increased ecNOS mRNA half-life. In contrast, incubation of cells with higher albeit subtoxic concentrations of AmB (2.5–5.0 μg ml−1) resulted in a decrease or respectively in completely abolished ecNOS mRNA and protein expression with a strongly reduced or inhibited ecNOS activity, due to a decrease of ecNOS mRNA half-life. None of the AmB concentrations affected promoter activity as found with a reporter gene construct stably transfected into ECV304 cells.Thus, our experiments show a concentration-dependent biphasic effect of AmB on expression and activity of ecNOS, an effect best explained by AmB influencing ecNOS mRNA stability. In view of the known renal accumulation of this drug the results reported here could help to elucidate its renal toxicity. PMID:11015297

  17. Altered Modulation of Silent Period in Tongue Motor Cortex of Persistent Developmental Stuttering in Relation to Stuttering Severity

    PubMed Central

    Busan, Pierpaolo; Del Ben, Giovanni; Bernardini, Simona; Natarelli, Giulia; Bencich, Marco; Monti, Fabrizio; Manganotti, Paolo; Battaglini, Piero Paolo

    2016-01-01

    Motor balance in developmental stuttering (DS) was investigated with Transcranial Magnetic Stimulation (TMS), with the aim to define novel neural markers of persistent DS in adulthood. Eleven DS adult males were evaluated with TMS on tongue primary motor cortex, compared to 15 matched fluent speakers, in a “state” condition (i.e. stutterers vs. fluent speakers, no overt stuttering). Motor and silent period thresholds (SPT), recruitment curves, and silent period durations were acquired by recording tongue motor evoked potentials. Tongue silent period duration was increased in DS, especially in the left hemisphere (P<0.05; Hedge’s g or Cohen’s dunbiased = 1.054, i.e. large effect size), suggesting a “state” condition of higher intracortical inhibition in left motor cortex networks. Differences in motor thresholds (different excitatory/inhibitory ratios in DS) were evident, as well as significant differences in SPT. In fluent speakers, the left hemisphere may be marginally more excitable than the right one in motor thresholds at lower muscular activation, while active motor thresholds and SPT were higher in the left hemisphere of DS with respect to the right one, resulting also in a positive correlation with stuttering severity. Pre-TMS electromyography data gave overlapping evidence. Findings suggest the existence of a complex intracortical balance in DS tongue primary motor cortex, with a particular interplay between excitatory and inhibitory mechanisms, also in neural substrates related to silent periods. Findings are discussed with respect to functional and structural impairments in stuttering, and are also proposed as novel neural markers of a stuttering “state” in persistent DS, helping to define more focused treatments (e.g. neuro-modulation). PMID:27711148

  18. 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

  19. Hemodynamics in Coronary Arterial Tree of Serial Stenoses

    PubMed Central

    Lu, Bin; Jia, Xinwei; Zhong, Liang; Kassab, Ghassan S.; Tan, Wenchang

    2016-01-01

    Serial segmental narrowing frequently occurs in humans, which alters coronary hemodynamics and further affects atherosclerotic progression and plaque formation. The objective of this study was to understand the distribution of hemodynamic parameters in the epicardial left main coronary arterial (LMCA) tree with serial stenoses reconstructed from patient computer tomography angiography (CTA) images. A finite volume method was used in conjunction with the inlet pressure wave and outlet flow resistance. The time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) were determined from the flow field. A stenosis at a mother vessel mainly deteriorated the hemodynamics near the bifurcation while a stenosis at a daughter vessel affected the remote downstream bifurcation. In comparison with a single stenosis, serial stenoses increased the peak pressure gradient along the main trunk of the epicardial left anterior descending arterial tree by > 50%. An increased distance between serial stenoses further increased the peak pressure gradient. These findings have important implications on the diagnosis and treatment of serial coronary stenoses. PMID:27685989

  20. Particle Image Velocimetry studies of bicuspid aortic valve hemodynamics

    NASA Astrophysics Data System (ADS)

    Saikrishnan, Neelakantan; Yap, Choon-Hwai; Yoganathan, Ajit P.

    2010-11-01

    Bicuspid aortic valves (BAVs) are a congenital anomaly of the aortic valve with two fused leaflets, affecting about 1-2% of the population. BAV patients have much higher incidence of valve calcification & aortic dilatation, which may be related to altered mechanical forces from BAV hemodynamics. This study aims to characterize BAV hemodynamics using Particle Image Velocimetry(PIV). BAV models are constructed from normal explanted porcine aortic valves by suturing two leaflets together. The valves are mounted in an acrylic chamber with two sinuses & tested in a pulsatile flow loop at physiological conditions. 2D PIV is performed to obtain flow fields in three planes downstream of the valve. The stenosed BAV causes an eccentric jet, resulting in a very strong vortex in the normal sinus. The bicuspid sinus vortex appears much weaker, but more unstable. Unsteady oscillatory shear stresses are also observed, which have been associated with adverse biological response; characterization of the hemodynamics of BAVs will provide the first step to understanding these processes better. Results from multiple BAV models of varying levels of stenosis will be presented & higher stenosis corresponded to stronger jets & increased aortic wall shear stresses.

  1. The effects of hemodynamic lag on functional connectivity and behavior after stroke.

    PubMed

    Siegel, Joshua S; Snyder, Abraham Z; Ramsey, Lenny; Shulman, Gordon L; Corbetta, Maurizio

    2016-12-01

    Stroke disrupts the brain's vascular supply, not only within but also outside areas of infarction. We investigated temporal delays (lag) in resting state functional magnetic resonance imaging signals in 130 stroke patients scanned two weeks, three months and 12 months post stroke onset. Thirty controls were scanned twice at an interval of three months. Hemodynamic lag was determined using cross-correlation with the global gray matter signal. Behavioral performance in multiple domains was assessed in all patients. Regional cerebral blood flow and carotid patency were assessed in subsets of the cohort using arterial spin labeling and carotid Doppler ultrasonography. Significant hemodynamic lag was observed in 30% of stroke patients sub-acutely. Approximately 10% of patients showed lag at one-year post-stroke. Hemodynamic lag corresponded to gross aberrancy in functional connectivity measures, performance deficits in multiple domains and local and global perfusion deficits. Correcting for lag partially normalized abnormalities in measured functional connectivity. Yet post-stroke FC-behavior relationships in the motor and attention systems persisted even after hemodynamic delays were corrected. Resting state fMRI can reliably identify areas of hemodynamic delay following stroke. Our data reveal that hemodynamic delay is common sub-acutely, alters functional connectivity, and may be of clinical importance.

  2. Comparing a non-invasive hemodynamic monitor with minimally invasive monitoring during major open abdominal surgery

    PubMed Central

    Ong, Lawrence; Liu, Hong

    2014-01-01

    Abstract As part of the enhanced recovery after surgery (ERAS) protocol, the goal-directed fluid management with hemodynamic monitoring can effectively guide perioperative fluid use and significantly improve the outcomes in high-risk patients undergoing major surgeries. Several minimally invasive and non-invasive monitoring devices are commercially available for clinical use. As part of an internal evaluation, we reported the results from three different hemodynamic monitoring devices used in a patient undergoing a major abdominal surgery. PMID:25050116

  3. The effect of trabeculectomy on ocular hemodynamics.

    PubMed Central

    Cantor, L B

    2001-01-01

    PURPOSE: To evaluate the effects of chronic reduction of intraocular pressure (IOP) on ocular hemodynamics. METHODS: Multisite, prospective evaluation of patients requiring trabeculectomy for treatment of glaucoma. Patients were recruited from the glaucoma service of 2 university hospitals. Patients were evaluated prior to surgery and at 3, 6, and 12 months after trabeculectomy. Color Doppler imaging was used to measure blood flow in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries. Heidelberg retinal flowmetry was used to evaluate perfusion in the peripapillary and optic disc capillary beds. IOP was measured at baseline and at each study visit. RESULTS: There were highly significant reductions in IOP from presurgical baseline measures. At 3 months, mean IOP reduction was 17.1 mm Hg (62.3%; P < .001). At the 6- and 12-month evaluations, the mean IOP reductions were 15.7 mm Hg (57.3%) and 15.5 mm Hg (56.5%), respectively, P < .001. Despite the significant reduction in IOP, there were no significant differences in any ocular blood flow parameters before and after trabeculectomy. CONCLUSIONS: The findings of this study suggest that chronic reduction of IOP does not alter ocular blood flow and that IOP may be an independent risk factor for progression of glaucoma. These findings also suggest that the eye has the ability to autoregulate to chronically increased IOP over time and that additional studies evaluating the long-term effects of IOP changes are needed to further define this relationship. PMID:11797313

  4. Several Hfq-dependent alterations in physiology of Yersinia enterocolitica O:3 are mediated by derepression of the transcriptional regulator RovM.

    PubMed

    Leskinen, Katarzyna; Pajunen, Maria I; Varjosalo, Markku; Fernández-Carrasco, Helena; Bengoechea, José A; Skurnik, Mikael

    2017-03-01

    In bacteria, the RNA chaperone Hfq enables pairing of small regulatory RNAs with their target mRNAs and therefore is a key player of post-transcriptional regulation network. As a global regulator, Hfq is engaged in the adaptation to external environment, regulation of metabolism and bacterial virulence. In this study we used RNA-sequencing and quantitative proteomics (LC-MS/MS) to elucidate the role of this chaperone in the physiology and virulence of Yersinia enterocolitica serotype O:3. This global approach revealed the profound impact of Hfq on gene and protein expression. Furthermore, the role of Hfq in the cell morphology, metabolism, cell wall integrity, resistance to external stresses and pathogenicity was evaluated. Importantly, our results revealed that several alterations typical for the hfq-negative phenotype were due to derepression of the transcriptional factor RovM. The overexpression of RovM caused by the loss of Hfq chaperone resulted in extended growth defect, alterations in the lipid A structure, motility and biofilm formation defects, as well as changes in mannitol utilization. Furthermore, in Y. enterocolitica RovM only in the presence of Hfq affected the abundance of RpoS. Finally, the impact of hfq and rovM mutations on the virulence was assessed in the mouse infection model.

  5. Simulation of hemodynamic responses to the valsalva maneuver: an integrative computational model of the cardiovascular system and the autonomic nervous system.

    PubMed

    Liang, Fuyou; Liu, Hao

    2006-02-01

    The Valsalva maneuver is a frequently used physiological test in evaluating the cardiovascular autonomic functions in human. Although a large pool of experimental data has provided substantial insights into different aspects of the mechanisms underlying the cardiovascular regulations during the Valsalva maneuver, so far a complete comprehension of these mechanisms and the interactions among them is unavailable. In the present study, a computational model of the cardiovascular system (CVS) and its interaction with the autonomic nervous system (ANS) was developed for the purpose of quantifying the individual roles of the CVS and the ANS in the hemodynamic regulations during the Valsalva maneuver. A detailed computational compartmental parameter model of the global CVS, a system of mathematical equations representing the autonomic nervous reflex regulatory functions, and an empirical cerebral autoregulation (CA) model formed the main body of the present model. Based on simulations of the Valsalva maneuvers at several typical postures, it was demonstrated that hemodynamic responses to the maneuver were not only determined by the ANS-mediated cardiovascular regulations, but also significantly affected by the postural-change-induced hemodynamic alterations preceding the maneuver. Moreover, the large-magnitude overshoot in cerebral perfusion immediately after the Valsalva maneuver was found to result from a combined effect of the circulatory autonomic functions, the CA, and the cerebral venous blood pressure.

  6. Cerebrovascular hemodynamics during pranayama techniques

    PubMed Central

    Nivethitha, L.; Mooventhan, A.; Manjunath, N. K.; Bathala, Lokesh; Sharma, Vijay K.

    2017-01-01

    Background: Pranayama techniques are known to produce variable physiological effects on the body. We evaluated the effect of the two commonly practiced Pranayama techniques on cerebral hemodynamics. Materials and Methods: Fifteen healthy male volunteers, trained in Yoga and Pranayama, were included in the study. Mean age was 24 years (range 22–32 years). Study participants performed 2 Pranayamas in 2 different orders. Order 1 (n = 7) performed Bhastrika (bellows breaths) followed by Kumbhaka (breath retention) while order 2 (n = 8) performed Kumbhaka followed by Bhastrika. Both breathing techniques were performed for 1 min each. Continuous transcranial Doppler (TCD) monitoring was performed during the breathing techniques. TCD parameters that were recorded included peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity (MFV), and pulsatility index (PI) of the right middle cerebral artery at baseline, 15, 30, 45, and 60 s. Results: Significant reductions in EDV (3.67 ± 6.48; P < 0.001) and MFV (22.00 ± 7.30; P < 0.001) with a significant increase in PI (2.43 ± 0.76; P < 0.001) were observed during Bhastrika. On the contrary, a significant increase in PSV (65.27 ± 13.75; P < 0.001), EDV (28.67 ± 12.03; P < 0.001), and MFV (43.67 ± 12.85; P < 0.001) with a significant reduction in PI (0.89 ± 0.28; P < 0.01) was observed only during Kumbhaka. Conclusion: Bhastrika and Kumbhaka practices of Pranayama produce considerable and opposing effects on cerebral hemodynamic parameters. Our findings may play a potential role in designing the Pranayama techniques according to patients’ requirements. PMID:28149083

  7. Current Developments and Future Applications of Intracoronary Hemodynamics

    PubMed Central

    Coverstone, Edward; Shapiro, Robert; Singh, Jasvindar

    2015-01-01

    Intracoronary hemodynamic assessment of the physiologic significance of coronary lesions improves clinical outcomes in patients with coronary artery disease. Coronary flow velocity reserve (CFVR), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and index of microcirculatory resistance (IMR) utilize sensor-mounted guidewires to approximate coronary flow. CFVR and FFR rely on pharmacologic administration of adenosine to achieve hyperemia and diagnose epicardial lesion severity. As an adenosine-free index, iFR utilizes a wave-free period in mid-late diastole during which resistance is constant and low to assess lesion significance. IMR combines hyperemic pressure measurements with thermodilution to quantify microvascular resistance. We review the physiology, clinical trials, and clinical applications of these invasive hemodynamic assessments. PMID:25946656

  8. Evaluation of the hemodynamic impact of continuous renal replacement therapy in healthy dogs.

    PubMed

    Shimokawa Miyama, Takako; Itamoto, Kazuhito; Yoshioka, Chihiro; Minami, Koji; Okawa, Takumi; Fujisaki, Yuka; Hiraoka, Hiroko; Mizuno, Takuya; Okuda, Masaru

    2010-04-01

    We performed continuous renal replacement therapy (CRRT) on clinically healthy dogs to evaluate the effects of CRRT on hemodynamics. Heart rate, arterial blood pressure, and central venous pressure of the dogs (n=6) were recorded during the procedure, which was performed under general anesthesia. Throughout the CRRT, heart rate and arterial blood pressure were stable. Central venous pressure increased after CRRT termination but returned to the basal level within 30 min. In this study, hemodynamic alterations, including hypotension, hypertension, and arrhythmias, were not observed during CRRT. These observations suggest that the CRRT protocol used in the present study can be safely applied to clinical cases with acute renal failure.

  9. 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

    2015-01-01

    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.

  10. 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

  11. Determining the resilience of carbon dynamics in semi-arid biomes of the Southwestern US to severe drought and altered rainfall patterns

    NASA Astrophysics Data System (ADS)

    Litvak, M. E.; Krofcheck, D. J.; Hilton, T. W.; Fox, A. M.; Osuna, J. L.

    2011-12-01

    Water is critically important for biotic processes in semi-arid ecosystems and 2011 is developing as one of the most severe drought years on record for many parts of the Southwestern US. To quantify the impact of this severe drought on regional carbon and energy balance, we need a more detailed understanding of how water limitation alters ecosystem processes across a range of semi-arid biomes. We quantified the impact of severe drought and changes in both the quantity and distribution of precipitation on ecosystem biotic structure and function across the range of biomes represented in the NM elevation gradient network (desert grassland, creosote shrubland, juniper savanna, piñon-juniper woodland, ponderosa pine forest and subalpine mixed conifer forest). We compared how daily, seasonal and annual carbon and energy balance and their components in each of these biomes respond to changes in rainfall patterns using continuous measurements of carbon, water and energy exchange and associated measurements in each of these biomes during a 5 year period (2006-2011) that included a severe drought, and large variability in both winter precipitation and the timing and intensity of the monsoon. To understand the underlying mechanisms, we used time series of radiation absorbed by vegetation, surface albedo, soil moisture storage, phenology, gross primary productivity (GPP), ecosystem respiration (Re), and WorldView-2 images acquired pre- and post-monsoon in each of these biomes. In all of the biomes except the desert grassland site, the strength and timing of both winter and monsoon precipitation are important controls over carbon and energy dynamics in this region, though we see site-specific sensitivities across the elevation gradient. Over the past 5 years, carbon dynamics in the desert grassland site appears to be decoupled from winter precipitation. In addition, carbon dynamics in disturbed grassland and pinon-juniper ecosystems were more sensitive to severe drought than

  12. Non-Newtonian effects of blood flow on hemodynamics in distal vascular graft anastomoses.

    PubMed

    Chen, Jie; Lu, Xi-Yun; Wang, Wen

    2006-01-01

    Non-Newtonian fluid flow in a stenosed coronary bypass is investigated numerically using the Carreau-Yasuda model for the shear thinning behavior of the blood. End-to-side coronary bypass anastomosis is considered in a simplified model geometry where the host coronary artery has a 75% severity stenosis. Different locations of the bypass graft to the stenosis and different flow rates in the graft and in the host artery are studied. Particular attention is given to the non-Newtonian effect of the blood on the primary and secondary flow patterns in the host coronary artery and the wall shear stress (WSS) distribution there. Interaction between the jet flow from the stenosed artery and the flow from the graft is simulated by solving the three-dimensional Navier-Stokes equation coupled with the non-Newtonian constitutive model. Results for the non-Newtonian flow, the Newtonian flow and the rescaled Newtonian flow are presented. Significant differences in axial velocity profiles, secondary flow streamlines and WSS between the non-Newtonian and Newtonian fluid flows are revealed. However, reasonable agreement between the non-Newtonian and the rescaled Newtonian flows is found. Results from this study support the view that the residual flow in a partially occluded coronary artery interacts with flow in the bypass graft and may have significant hemodynamic effects in the host vessel downstream of the graft. Non-Newtonian property of the blood alters the flow pattern and WSS distribution and is an important factor to be considered in simulating hemodynamic effects of blood flow in arterial bypass grafts.

  13. Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy.

    PubMed

    Lu, Yang; Bernabeu, Miguel O; Lammer, Jan; Cai, Charles C; Jones, Martin L; Franco, Claudio A; Aiello, Lloyd Paul; Sun, Jennifer K

    2016-12-01

    Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients.

  14. Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy

    PubMed Central

    Lu, Yang; Bernabeu, Miguel O.; Lammer, Jan; Cai, Charles C.; Jones, Martin L.; Franco, Claudio A.; Aiello, Lloyd Paul; Sun, Jennifer K.

    2016-01-01

    Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients. PMID:28078170

  15. 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.

  16. 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

  17. 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; Gianesini, Sergio; 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.

  18. Alterations in Low-Level Perceptual Networks Related to Clinical Severity in PTSD after an Earthquake: A Resting-State fMRI Study

    PubMed Central

    Shang, Jing; Meng, Yajing; Zhu, Hongru; Qiu, Changjian; Gong, Qiyong; Liao, Wei

    2014-01-01

    Background Several task-based functional MRI (fMRI) studies have highlighted abnormal activation in specific regions involving the low-level perceptual (auditory, visual, and somato-motor) network in posttraumatic stress disorder (PTSD) patients. However, little is known about whether the functional connectivity of the low-level perceptual and higher-order cognitive (attention, central-execution, and default-mode) networks change in medication-naïve PTSD patients during the resting state. Methods We investigated the resting state networks (RSNs) using independent component analysis (ICA) in 18 chronic Wenchuan earthquake-related PTSD patients versus 20 healthy survivors (HSs). Results Compared to the HSs, PTSD patients displayed both increased and decreased functional connectivity within the salience network (SN), central executive network (CEN), default mode network (DMN), somato-motor network (SMN), auditory network (AN), and visual network (VN). Furthermore, strengthened connectivity involving the inferior temporal gyrus (ITG) and supplementary motor area (SMA) was negatively correlated with clinical severity in PTSD patients. Limitations Given the absence of a healthy control group that never experienced the earthquake, our results cannot be used to compare alterations between the PTSD patients, physically healthy trauma survivors, and healthy controls. In addition, the breathing and heart rates were not monitored in our small sample size of subjects. In future studies, specific task paradigms should be used to reveal perceptual impairments. Conclusions These findings suggest that PTSD patients have widespread deficits in both the low-level perceptual and higher-order cognitive networks. Decreased connectivity within the low-level perceptual networks was related to clinical symptoms, which may be associated with traumatic reminders causing attentional bias to negative emotion in response to threatening stimuli and resulting in emotional dysregulation. PMID

  19. Local Inflammation Alters MMP-2 and MMP-9 Gelatinase Expression Associated with the Severity of Nifedipine-Induced Gingival Overgrowth: a Rat Model Study.

    PubMed

    Li, Wu-Li; Wu, Cheng-Hai; Yang, Jun; Tang, Min; Chen, Long-Jie; Zhao, Shou-Liang

    2015-08-01

    Nifedipine-induced gingival overgrowth (NIGO) is characterized by cell proliferation and extracellular matrix (ECM) component accumulation in gingival connective tissues, with varying degrees of inflammation and fibrosis. Impaired collagen and ECM homeostasis may be among the underlying molecular mechanisms that lead to the fibrotic changes that occur in drug-induced gingival overgrowth (DIGO). Because matrix metalloproteinases (MMPs) play vital roles in regulating collagen and ECM metabolism, many studies have been performed to reveal the relationship between MMPs and DIGO. It is thought that the gelatinases MMP-2 and MMP-9, both type IV collagenases, are involved in the development of tissue inflammation and organ fibrosis. However, the few studies regarding gelatinase expression in DIGO are controversial. Recent studies have demonstrated the inhibitory effect of cyclosporine A (CsA) on gelatinase expression and/or activity; however, similar changes have yet to be detected in Nif-treated gingival tissues. In this study, we verified that Nif treatment could lead to gingival overgrowth in rats and that gingival inflammation played a pro-proliferative role in NIGO development. Additionally, we examined the temporal expression of gelatinases on days 0, 7, 14, 21, 30, and 40 during NIGO development. The aim was to investigate whether MMP-2 and MMP-9 played significant roles in regulating NIGO development and progression. MMP-2 gene expression was not altered by Nif treatment alone but was significantly inhibited by Nif treatment for 30 days in the presence of local inflammation. However, no significant alterations in MMP-2 protein expression were detected in the Nif-treated gingival tissue, regardless of the presence or absence of local inflammation. Moreover, Nif treatment could lead to transient and significant increases in MMP-9 gene and protein expression levels in the presence of local inflammation. In particular, active MMP-9 expression increased significantly

  20. Neutralization of MMP-2 and TNFR1 Regulates the Severity of S. aureus-Induced Septic Arthritis by Differential Alteration of Local and Systemic Proinflammatory Cytokines in Mice.

    PubMed

    Sultana, Sahin; Adhikary, Rana; Bishayi, Biswadev

    2017-03-22

    Despite advancement in the field of antibiotics septic arthritis remains a serious concern till date. Staphylococcus aureus is the most common bacterium that causes septic arthritis. Severity of this disease is directly correlated with chronic inflammation induced by proinflammatory cytokines like TNF-α, interleukin (IL)-1β, IL-6, and induction of matrix metalloproteinases (MMPs) including MMP-2. The objective of our study was to evaluate the role of MMP-2 and tumor necrosis factor receptor 1 (TNFR1) in the pathogenesis of S. aureus infection-induced septic arthritis. Mice were infected with live S. aureus (5 × 10(6) cells/ml) followed by administration of MMP-2 inhibitor and TNFR1 antibody. Arthritis index showed highest reduction in severity of arthritis in mice treated with both MMP-2 inhibitor and TNFR1 antibody after infection. Combined neutralization of MMP-2 and TNFR1 led to marked diminution in bacterial count in the combined group. Lowest levels of pro inflammatory cytokines like TNF-α, IL-1β, IL-6, and IFN-γ were observed in both serum and synovial tissues indicating maximum protection in S. aureus arthritis during combination treatment. Increment in the level of IL-10 in the combination group could be positively correlated with the recovery of arthritis. Similarly, expressions of COX-2 and iNOS, markers of acute inflammation were also significantly reduced in the combination group due to resolution of inflammation. Levels of O2(.-) and NO also showed a significant fall in case of the group treated with MMP-2 inhibitor and TNFR1 antibody both. Neutralization of both MMP-2 and TNFR1 caused rapid decline in recruitment of neutrophil and macrophages in the synovial tissues as evident from reduced MPO and MCP-1 levels, respectively, compared to other groups. Overall, it can be suggested that administration of MMP-2 inhibitor and TNFR1 antibody in combination is protective against the severity of inflammation and cartilage destruction associated with S

  1. Post-stenotic Recirculating Flow May Cause Hemodynamic Perforator Infarction

    PubMed Central

    Kim, Bum Joon; Ha, Hojin; Huh, Hyung Kyu; Kim, Guk Bae; Kim, Jong S.; Kim, Namkug; Lee, Sang-Joon; Kang, Dong-Wha; Kwon, Sun U.

    2016-01-01

    Background and Purpose The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. Methods 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. Results A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). Conclusions Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis. PMID:26687122

  2. Hemodynamic Features of Symptomatic Vertebrobasilar Disease

    PubMed Central

    Amin-Hanjani, Sepideh; Du, Xinjian; Rose-Finnell, Linda; Pandey, Dilip K.; Richardson, DeJuran; Thulborn, Keith R.; Elkind, Mitchell S.V.; Zipfel, Gregory J.; Liebeskind, David S.; Silver, Frank L.; Kasner, Scott E.; Aletich, Victor A.; Caplan, Louis R.; Derdeyn, Colin P.; Gorelick, Philip B; Charbel, Fady T.

    2015-01-01

    Background and Purpose Atherosclerotic vertebrobasilar (VB) disease is an important etiology of posterior circulation stroke. To examine the role of hemodynamic compromise, a prospective multi-center study, Vertebrobasilar Flow Evaluation and Risk of Transient Ischemic Attack and Stroke (VERiTAS), was conducted. Here we report clinical features and vessel flow measurements from the study cohort. Methods Patients with recent VB TIA or stroke and ≥50% atherosclerotic stenosis or occlusion in vertebral (VA) and/or basilar (BA) arteries were enrolled. Large vessel flow in the VB territory was assessed using quantitative MRA. Results The cohort (n=72, 44% female) had a mean age of 65.6 years; 72% presented with ischemic stroke. Hypertension (93%) and hyperlipidemia (81%) were the most prevalent vascular risk factors. BA flows correlated negatively with percentage stenosis in the affected vessel, and positively to the minimal diameter at the stenosis site (p<0.01). A relative threshold effect was evident, with flows dropping most significantly with ≥80% stenosis/occlusion (p<0.05). Tandem disease involving the BA and either/both VAs had the greatest negative impact on immediate downstream flow in the BA (43 ml/min vs. 71 ml/min, p=0.01). Distal flow status assessment, based on an algorithm incorporating collateral flow by examining distal vessels (BA and posterior cerebral arteries), correlated neither with multifocality of disease nor severity of the maximal stenosis. Conclusions Flow in stenotic posterior circulation vessels correlates with residual diameter, and drops significantly with tandem disease. However, distal flow status, incorporating collateral capacity, is not well predicted by the severity or location of the disease. PMID:25977279

  3. Practical issues of hemodynamic monitoring at the bedside.

    PubMed

    Polanco, Patricio M; Pinsky, Michael R

    2006-12-01

    The hemodynamic monitoring of a surgical patient acquires a major relevance in high-risk patients and those suffering from surgical diseases associated with hemodynamic instability, such as hemorrhagic or septic shock. This article reviews the fundamental physiologic principles needed to understand hemodynamic monitoring at the bedside. Monitoring defines stability, instability, and response to therapy. The major hemodynamic parameters measured and derived from invasive hemodynamic monitoring, such as arterial, central venous, and pulmonary catheterization, are discussed, as are its clinical indications, benefits, and complications. The current clinical data relevant to hemodynamic monitoring are reviewed and discussed.

  4. Hemodynamic Changes following Aortic Valve Bypass: A Mathematical Approach

    PubMed Central

    Benevento, Emilia; Djebbari, Abdelghani; Keshavarz-Motamed, Zahra; Cecere, Renzo; Kadem, Lyes

    2015-01-01

    Aortic valve bypass (AVB) has been shown to be a viable solution for patients with severe aortic stenosis (AS). Under this circumstance, the left ventricle (LV) has a double outlet. The objective was to develop a mathematical model capable of evaluating the hemodynamic performance following the AVB surgery. A mathematical model that captures the interaction between LV, AS, arterial system, and AVB was developed. This model uses a limited number of parameters that all can be non-invasively measured using patient data. The model was validated using in vivo data from the literature. The model was used to determine the effect of different AVB and AS configurations on flow proportion and pressure of the aortic valve and the AVB. Results showed that the AVB leads to a significant reduction in transvalvular pressure gradient. The percentage of flow through the AVB can range from 55.47% to 69.43% following AVB with a severe AS. LV stroke work was also significantly reduced following the AVB surgery and reached a value of around 1.2 J for several AS severities. Findings of this study suggest: 1) the AVB leads to a significant reduction in transvalvular pressure gradients; 2) flow distribution between the AS and the AVB is significantly affected by the conduit valve size; 3) the AVB leads to a significant reduction in LV stroke work; and 4) hemodynamic performance variations can be estimated using the model. PMID:25881082

  5. Neonatal aortic arch hemodynamics and perfusion during cardiopulmonary bypass.

    PubMed

    Pekkan, Kerem; Dur, Onur; Sundareswaran, Kartik; Kanter, Kirk; Fogel, Mark; Yoganathan, Ajit; Undar, Akif

    2008-12-01

    The objective of this study is to quantify the detailed three-dimensional (3D) pulsatile hemodynamics, mechanical loading, and perfusion characteristics of a patient-specific neonatal aortic arch during cardiopulmonary bypass (CPB). The 3D cardiac magnetic resonance imaging (MRI) reconstruction of a pediatric patient with a normal aortic arch is modified based on clinical literature to represent the neonatal morphology and flow conditions. The anatomical dimensions are verified from several literature sources. The CPB is created virtually in the computer by clamping the ascending aorta and inserting the computer-aided design model of the 10 Fr tapered generic cannula. Pulsatile (130 bpm) 3D blood flow velocities and pressures are computed using the commercial computational fluid dynamics (CFD) software. Second order accurate CFD settings are validated against particle image velocimetry experiments in an earlier study with a complex cardiovascular unsteady benchmark. CFD results in this manuscript are further compared with the in vivo physiological CPB pressure waveforms and demonstrated excellent agreement. Cannula inlet flow waveforms are measured from in vivo PC-MRI and 3 kg piglet neonatal animal model physiological experiments, distributed equally between the head-neck vessels and the descending aorta. Neonatal 3D aortic hemodynamics is also compared with that of the pediatric and fetal aortic stages. Detailed 3D flow fields, blood damage, wall shear stress (WSS), pressure drop, perfusion, and hemodynamic parameters describing the pulsatile energetics are calculated for both the physiological neonatal aorta and for the CPB aorta assembly. The primary flow structure is the high-speed canulla jet flow (approximately 3.0 m/s at peak flow), which eventually stagnates at the anterior aortic arch wall and low velocity flow in the cross-clamp pouch. These structures contributed to the reduced flow pulsatility (85%), increased WSS (50%), power loss (28%), and blood

  6. The role of venous capacitance, circulating catecholamines, and heart rate in the hemodynamic response to increased temperature and hypoxia in the dogfish.

    PubMed

    Sandblom, Erik; Cox, Georgina K; Perry, Steve F; Farrell, Anthony P

    2009-05-01

    Hypoxia and increased temperature alter venous blood pressures in teleosts through active changes in venous tone. Elasmobranchs possess a capacious venous system but have limited adrenergic vascular innervation and subambient central venous pressure (P(cv)). In this study, we explored venous hemodynamic responses to acute temperature increase and moderate (6.9 kPa) and severe (2.5 kPa) hypoxia in the dogfish (Squalus acanthias). Normoxic dogfish at 10 degrees C had a P(cv) between -0.08 and -0.04 kPa and a mean circulatory filling pressure (P(mcf)) of approximately 0.12 kPa. At 16 degrees C, heart rate (f(H)), cardiac output (Q), and P(mcf) increased but P(cv) and plasma epinephrine and norepinephrine levels were unchanged. In contrast, moderate and severe hypoxia increased P(cv) and decreased Q and stroke volume (V(S)). f(H) decreased in severe hypoxia, whereas P(mcf) was unaffected despite elevated catecholamine levels. Atropine abolished hypoxic reductions in Q, V(S), and f(H), but P(cv) still increased. In contrast to the response in teleosts, this study on dogfish suggests that venous capacitance changes associated with warming and hypoxia are minimal and likely not mediated by circulating catecholamines. Thus hemodynamic status of the capacious elasmobranch venous circulation is potentially regulated by blood volume shifts from passive flow-mediated events and possibly through myogenic mechanisms.

  7. [Comparison of clinical assessment and invasive evaluation of hemodynamic parameters in septic shock].

    PubMed

    Vucić, N; Pilas, V

    1995-06-01

    The authors compare, in this prospective study, the accuracy of their own clinical assessment of hemodynamic parameters and severity of disease with the findings obtained by right heart catheterization in 50 patients with septic shock. The purpose of the study was to determine whether Swan-Ganz catheter insertion was necessary in all patients with septic shock. As soon as the diagnosis was established, the value of pulmonary capillary wedge pressure was estimated, as well as presence or absence of pathological uptake/supply dependency in all patients. The latter is an excellent indicator of severity of disease. The accurate assessment was noted in 27 (54%) patients (1. investigator), and in 30 (60%) patients (2. investigator). The sensitivity of detection of pathological uptake/supply dependency amounted to 53% and 65%; specificity was 73% and 79%, respectively. The therapy was altered in 21 patients (42%) after catheter insertion. The results were tested with chi2-test (p < 0.01). The findings of this study warrant catheter insertion in patients with septic shock.

  8. Severe hypertension in children and adolescents: pathophysiology and treatment.

    PubMed

    Flynn, Joseph T; Tullus, Kjell

    2009-06-01

    Severe, symptomatic hypertension occurs uncommonly in children, usually only in those with underlying congenital or acquired renal disease. If such hypertension has been long-standing, then rapid blood pressure reduction may be risky due to altered cerebral hemodynamics. While many drugs are available for the treatment of severe hypertension in adults, few have been studied in children. Despite the lack of scientific studies, some agents, particularly continuous intravenous infusions of nicardipine and labetalol, are preferred in many centers. These agents generally provide the ability to control the magnitude and rapidity of blood pressure reduction and should--in conjunction with careful patient monitoring--allow the safe reduction of blood pressure and the avoidance of complications. This review provides a summary of the underlying causes and pathophysiology of acute severe hypertension in childhood as well as a detailed discussion of drug treatment and the optimal clinical approach to managing children and adolescents with acute severe hypertension.

  9. Hemodynamic effects of mebutamate in spontaneously hypertensive rats.

    PubMed

    Pfeffer, J M; Pfeffer, M A; Frohlich, E D

    1975-05-01

    The acute hemodynamic effects of the antihypertensive agent mebutamate were evaluated in spontaneously hypertensive and normotensive Wistar rats. Arterial and venous pressures and cardiac output (electromagnetic flowmeter) were recorded in artificially ventilated, open-chest, ether-anesthetized animals before and after varying doses of mebutamate were injected intravenously. In both normotensive and hypertensive rats mebutamate produced a moderate decrease in arterial pressure which was associated with a reduction in both heart rate and cardiac output; total peripheral resistance remained unchanged. These data suggest that mebutamate may have therapuetic value in reducing arterial pressure in mild to moderately severe hypertensive patients.

  10. Enteral nutrition in the hemodynamically unstable critically ill patient.

    PubMed

    Flordelís Lasierra, J L; Pérez-Vela, J L; Montejo González, J C

    2015-01-01

    The benefit of enteral nutrition in critically ill patients has been demonstrated by several studies, especially when it is started early, in the first 24-48h of stay in the Intensive Care Unit, and this practice is currently advised by the main clinical guidelines. The start of enteral nutrition is controversial in patients with hemodynamic failure, since it may trigger intestinal ischemia. However, there are data from experimental studies in animals, as well as from observational studies in humans that allow for hypotheses regarding its beneficial effect and safety. Interventional clinical trials are needed to confirm these findings.

  11. Post-operative consequences of hemodynamic optimization.

    PubMed

    Lazkani, A; Lebuffe, G

    2016-12-01

    Hemodynamic optimization begins with a medical assessment to identify the high-risk patients. This stratification is needed to customize the choice of hemodynamic support that is best adapted to the patient's level of risk, integrating the use of the least invasive procedures. The macro-circulatory hemodynamic approach aims to maintain a balance between oxygen supply (DO2) and oxygen demand (VO2). Volume replacement plays a crucial role based on the titration of fluid boluses according to their effect on measured stroke volume or indices of preload dependency. Good function of the microcirculatory system is the best guarantee to achieve this goal. An assessment of the DO2/VO2 ratio is needed for guidance in critical situations where tissue hypoxia may occur. Overall, all of these strategies are based on objective criteria to guide vascular replacement and/or tissue oxygenation in order to improve the patient's post-operative course by decreasing morbidity and hospital stay.

  12. Flow-volume loops derived from three-dimensional echocardiography: a novel approach to the assessment of left ventricular hemodynamics

    PubMed Central

    Shahgaldi, Kambiz; Söderqvist, Emil; Gudmundsson, Petri; Winter, Reidar; Nowak, Jacek; Brodin, Lars-Åke

    2008-01-01

    Background This study explores the feasibility of non-invasive evaluation of left ventricular (LV) flow-volume dynamics using 3-dimensional (3D) echocardiography, and the capacity of such an approach to identify altered LV hemodynamic states caused by valvular abnormalities. Methods Thirty-one patients with moderate-severe aortic (AS) and mitral (MS) stenoses (21 and 10 patients, respectively) and 10 healthy volunteers underwent 3D echocardiography with full volume acquisition using Philips Sonos 7500 equipment. The digital 3D data were post- processed using TomTec software. LV flow-volume loops were subsequently constructed for each subject by plotting instantaneous LV volume data sampled throughout the cardiac cycle vs. their first derivative representing LV flow. After correction for body surface area, an average flow-volume loop was calculated for each subject group. Results Flow-volume loops were obtainable in all subjects, except 3 patients with AS. The flow-volume diagrams displayed clear differences in the form and position of the loops between normal individuals and the respective patient groups. In patients with AS, an "obstructive" pattern was observed, with lower flow values during early systole and larger end-systolic volume. On the other hand, patients with MS displayed a "restrictive" flow-volume pattern, with reduced diastolic filling and smaller end-diastolic volume. Conclusion Non-invasive evaluation of LV flow-volume dynamics using 3D-echocardiographic data is technically possible and the approach has a capacity to identify certain specific types of alteration of LV flow-volume pattern caused by valvular abnormalities, thus reflecting underlying hemodynamic states specific for these abnormalities. PMID:18394157

  13. [Hemodynamic evaluation of the patient with microvarices].

    PubMed

    Alvarez Sánchez, J A; Vega Gómez, M E; Rodríguez Lacaba, B; Martínez Griñán, M A

    1992-01-01

    The present study included 21 lower limbs with micro varicosities, 56 lower limbs with retrograde flow-varicosities (positive Rivlin) and 35 health lower limbs. Technics used for diagnosis were: Doppler ultrasonography and strain gauge plethysmography. We found a higher incidence of valvular failure on the varicose patients with retrograde flow (showing changes on their viscoelastic features of their venous walls). On the contrary, patient with microvaricosities showed an hemodynamics similar to the healty patient: we did not found any difference on the variables analyzed between the two groups. We conclude that the presence of microvaricosities has no influence on the analyzed hemodynamic parametres.

  14. Asymptomatic Pulmonary Vein Stenosis: Hemodynamic Adaptation and Successful Ablation

    PubMed Central

    Weinberg, Denis

    2016-01-01

    Pulmonary vein stenosis is a well-established possible complication following an atrial fibrillation ablation of pulmonary veins. Symptoms of pulmonary vein stenosis range from asymptomatic to severe exertional dyspnea. The number of asymptomatic patients with pulmonary vein stenosis is greater than originally estimated; moreover, only about 22% of severe pulmonary vein stenosis requires intervention. We present a patient with severe postatrial fibrillation (AF) ablation pulmonary vein (PV) stenosis, which was seen on multiple imaging modalities including cardiac computed tomography (CT) angiogram, lung perfusion scan, and pulmonary angiogram. This patient did not have any pulmonary symptoms. Hemodynamic changes within a stenosed pulmonary vein might not reflect the clinical severity of the obstruction if redistribution of pulmonary artery flow occurs. Our patient had an abnormal lung perfusion and ventilation (V/Q) scan, suggesting pulmonary artery blood flow redistribution. The patient ultimately underwent safe repeat atrial fibrillation ablation with successful elimination of arrhythmia. PMID:28105376

  15. 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

  16. 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.

  17. Stress Echocardiography in Aortic Stenosis: Insights into Valve Mechanics and Hemodynamics.

    PubMed

    Bermejo, Javier; García-Fernández, Miguel A.; Antoranz, J. Carlos; Moreno, M. Mar; Delcán, Juan Luis

    1999-10-01

    Stress interventions have been classically combined with cardiac catheterization recordings to understand the hemodynamic principles of valvular stenosis. Indices of aortic stenosis such as pressure gradient and valve area were based on simple hydraulic principles and have proved to be clinically useful for patient management during a number of decades. With the advent of Doppler echocardiography, these hemodynamic indices can be readily obtained noninvasively. Abundant evidence obtained using exercise and pharmacological stress echocardiography has demonstrated that the assumptions of classic hemodynamic models of aortic stenosis were wrong. Consequently, it is recognized that conventional indices may be misleading indicators of aortic stenosis significance in particular clinical situations. To improve diagnostic accuracy, several alternative hemodynamic models have been developed in the past few years, including valve resistance and left ventricular stroke work loss, among others. Nevertheless, these more-accurate indices should be obtainable noninvasively and need to demonstrate greater diagnostic and prognostic power than conventional indices; preliminary data suggest such superiority. Stress echocardiography is well established as the tool of choice for testing hypothesis and physical models of cardiac valve function. Although the final role of alternative indices is not yet well established, the new insights into valvular hemodynamics provided by this technique may change the clinical assessment of aortic stenosis.

  18. Resuscitation of traumatic shock: a hemodynamic review.

    PubMed

    Cottingham, Christine A

    2006-01-01

    Shock, or tissue hypoperfusion, is a frequent complication from traumatic injury. Despite the etiology of the shock state, there is always some component of hypovolemia. The body's innate ability to compensate for impaired perfusion may mask clinical signs, leading to delays in treatment. This article presents an overview of these compensatory mechanisms and resuscitation strategies from the vantage point of routine hemodynamic monitoring.

  19. Renal hemodynamic effects of relaxin in humans.

    PubMed

    Smith, Marie; Davison, John; Conrad, Kirk; Danielson, Lee

    2005-05-01

    Rat studies have convincingly demonstrated the essential role of the ovarian hormone relaxin in mediating gestational renal hemodynamic and osmoregulatory changes in that species. We describe a model in nonpregnant volunteers using exogenous hCG to stimulate the production and release of ovarian relaxin in order to assess renal hemodynamic responses. Women (n = 10) were serially studied +/- hCG stimulation during menstrual cycles with measurement of inulin, PAH, and neutral dextran clearances (to determine glomerular filtration rate [GFR], renal plasma flow [RPF], and glomerular porosity, respectively). Controls were women without ovarian function (n = 6) and men (n = 10). GFR and RPF were increased in the luteal phase compared to the follicular phase (15.3% increase in GFR, P < 0.005; 17.8% increase in RPF, P < 0.05). In controls, GFR and RPF were not significantly different between study occasions. Although exogenous hCG did not stimulate relaxin secretion in women without ovarian function or in men, it did so in normal women, but not into the pregnancy range. In no group were renal hemodynamics augmented by administered hCG. In naturally occurring cycles, increased serum relaxin is associated with augmented renal hemodynamics. As luteal stimulation with hCG failed to yield pregnancy relaxin levels, the use of exogenous relaxin for human administration is needed to further elucidate the renal vasodilatory properties of relaxin.

  20. 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...

  1. Hemodynamics of physiological blood flow in the aorta with nonlinear anisotropic heart valve

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Gilmanov, Anvar; Stolarski, Henryk

    2016-11-01

    The hemodynamic blood flow in cardiovascular system is one of the most important factor, which causing several vascular diseases. We developed a new Curvilinear Immersed Boundary - Finite Element - Fluid Structure Interaction (CURVIB-FE-FSI) method to analyze hemodynamic of pulsatile blood flow in a real aorta with nonlinear anisotropic aortic valve at physiological conditions. Hyperelastic material model, which is more realistic for describing heart valve have been incorporated in the CURVIB-FE-FSI code to simulate interaction of aortic heart valve with pulsatile blood flow. Comparative studies of hemodynamics for linear and nonlinear models of heart valve show drastic differences in blood flow patterns and hence differences of stresses causing impact at leaflets and aortic wall. This work is supported by the Lillehei Heart Institute at the University of Minnesota.

  2. 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.

  3. The impact of deformation of an aneurysm model under pulsatile flow on hemodynamic analysis.

    PubMed

    Kawakami, T; Takao, H; Ichikawa, C; Kamiya, K; Murayama, Y; Motosuke, M

    2016-08-01

    Hemodynamic analysis of cerebral aneurysms has been widely carried out to clarify the mechanisms of their growth and rupture. In several cases, patient-specific aneurysm models made of transparent polymers have been used. Even though periodic changes in aneurysms due to the pulsation of blood flow could be important, the deformation of the model geometry and its effect on hemodynamic evaluation has not been fully investigated. In addition, the fabrication accuracy of aneurysm models has not been evaluated even though it may affect the hemodynamic parameters to be analyzed. In this study, the fabrication accuracy of a silicone aneurysm model was investigated. Additionally, the deformation of the model under pulsatile flow as well as its correlation with flow behavior was evaluated. Consequently, a fabrication method for an aneurysm model with high accuracy was established and the importance of the wall thickness of the model was also specified.

  4. 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

  5. Functional Imaging of the Hemodynamic Sensory Gating Response in Schizophrenia

    PubMed Central

    Mayer, Andrew R.; Ruhl, David; Merideth, Flannery; Ling, Josef; Hanlon, Faith; Bustillo, Juan; Cañive, Jose

    2013-01-01

    The cortical (auditory and prefrontal) and/or subcortical (thalamic and hippocampal) generators of abnormal electrophysiological responses during sensory gating remain actively debated in the schizophrenia literature. Functional magnetic resonance imaging (fMRI) has the spatial resolution for disambiguating deep or simultaneous sources but has been relatively under-utilized to investigate generators of the gating response. Thirty patients with chronic schizophrenia (SP) and 30 matched controls participated in the current experiment. Hemodynamic response functions (HRF) for single (S1) and pairs (S1 + S2) of identical (IT; “gating-out” redundant information) or non-identical (NT; “gating-in” novel information) tones were generated through deconvolution. Increased or prolonged activation for patients in conjunction with deactivation for controls was observed within auditory cortex, prefrontal cortex and thalamus in response to single tones during the late hemodynamic response, and these group differences were not associated with clinical or cognitive symptomatology. Although patient hyper-activation to paired-tones conditions was present in several ROI, the effects were not statistically significant for either the gating-out or gating-in conditions. Finally, abnormalities in the post-undershoot of the auditory HRF were also observed for both single and paired tones conditions in patients. In conclusion, the amalgamation of the entire electrophysiological response to both S1 and S2 stimuli may limit hemodynamic sensitivity to paired tones during sensory gating, which may be more readily overcome by paradigms that utilize multiple stimuli rather than pairs. Patient hyperactivation following single tones is suggestive of deficits in basic inhibition, neurovascular abnormalities or a combination of both factors. PMID:22461278

  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. 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

  8. 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.

  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. 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.

  11. Misexpression of a Chloroplast Aspartyl Protease Leads to Severe Growth Defects and Alters Carbohydrate Metabolism in Arabidopsis1[C][W

    PubMed Central

    Paparelli, Eleonora; Gonzali, Silvia; Parlanti, Sandro; Novi, Giacomo; Giorgi, Federico M.; Licausi, Francesco; Kosmacz, Monika; Feil, Regina; Lunn, John E.; Brust, Henrike; van Dongen, Joost T.; Steup, Martin; Perata, Pierdomenico

    2012-01-01

    The crucial role of carbohydrate in plant growth and morphogenesis is widely recognized. In this study, we describe the characterization of nana, a dwarf Arabidopsis (Arabidopsis thaliana) mutant impaired in carbohydrate metabolism. We show that the nana dwarf phenotype was accompanied by altered leaf morphology and a delayed flowering time. Our genetic and molecular data indicate that the mutation in nana is due to a transfer DNA insertion in the promoter region of a gene encoding a chloroplast-located aspartyl protease that alters its pattern of expression. Overexpression of the gene (oxNANA) phenocopies the mutation. Both nana and oxNANA display alterations in carbohydrate content, and the extent of these changes varies depending on growth light intensity. In particular, in low light, soluble sugar levels are lower and do not show the daily fluctuations observed in wild-type plants. Moreover, nana and oxNANA are defective in the expression of some genes implicated in sugar metabolism and photosynthetic light harvesting. Interestingly, some chloroplast-encoded genes as well as genes whose products seem to be involved in retrograde signaling appear to be down-regulated. These findings suggest that the NANA aspartic protease has an important regulatory function in chloroplasts that not only influences photosynthetic carbon metabolism but also plastid and nuclear gene expression. PMID:22987884

  12. Optimal design for nonlinear estimation of the hemodynamic response function.

    PubMed

    Maus, Bärbel; van Breukelen, Gerard J P; Goebel, Rainer; Berger, Martijn P F

    2012-06-01

    Subject-specific hemodynamic response functions (HRFs) have been recommended to capture variation in the form of the hemodynamic response between subjects (Aguirre et al., [ 1998]: Neuroimage 8:360-369). The purpose of this article is to find optimal designs for estimation of subject-specific parameters for the double gamma HRF. As the double gamma function is a nonlinear function of its parameters, optimal design theory for nonlinear models is employed in this article. The double gamma function is linearized by a Taylor approximation and the maximin criterion is used to handle dependency of the D-optimal design on the expansion point of the Taylor approximation. A realistic range of double gamma HRF parameters is used for the expansion point of the Taylor approximation. Furthermore, a genetic algorithm (GA) (Kao et al., [ 2009]: Neuroimage 44:849-856) is applied to find locally optimal designs for the different expansion points and the maximin design chosen from the locally optimal designs is compared to maximin designs obtained by m-sequences, blocked designs, designs with constant interstimulus interval (ISI) and random event-related designs. The maximin design obtained by the GA is most efficient. Random event-related designs chosen from several generated designs and m-sequences have a high efficiency, while blocked designs and designs with a constant ISI have a low efficiency compared to the maximin GA design.

  13. 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.

  14. 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

  15. [Invasive and minimally invasive hemodynamic monitoring].

    PubMed

    Hansen, Matthias

    2016-10-01

    Advanced hemodynamic monitoring is necessary for adequate management of high-risk patients or patients with derangement of circulation. Studies demonstrate a benefit of early goal directed therapy in unstable cardiopulmonary situations. In these days we have different possibilities of minimally invasive or invasive hemodynamic monitoring. Minimally invasive measurements like pulse conture analysis or pulse wave analysis being less accurate under some circumstances, however only an artery catheter is needed for cardiac output monitoring. Pulmonary artery, transpulmonary thermodilution and lithium dilution technology have acceptable accuracy in cardiac output measurement. For therapy of unstable circulation there are additionally parameters to obtain. The pulmonary artery catheter is the device with the largest rate of complications, used by a trained crew and with a correct indication, his use is unchained justified.

  16. Comparison of hemodynamic, biochemical and hematological parameters of healthy pregnant women in the third trimester of pregnancy and the active labor phase

    PubMed Central

    2011-01-01

    Background Pregnancy is accompanied by several hemodynamic, biochemical and hematological changes which revert to normal values after labor. The mean values of these parameters have been reported for developed countries, but not for Mexican women. Furthermore, labor constitutes a stress situation, in which these factors may be altered. It is known that serologic increase of heat shock protein (Hsp) 70 is associated with abnormal pregnancies, presenting very low level in normal pregnant women. Nevertheless, there are no studies where these measurements are compared in healthy pregnant women at their third trimester of pregnancy (3TP) and the active labor phase (ActLP). Methods Seventy five healthy Mexican pregnant women were included. Hemodynamic, biochemical and hematological parameters were obtained in all cases, and serum Hsp70 levels were measured in a sample of 15 women at 3TP and at ActLP. Results Significant differences were found in most analysis performed and in Hsp70 concentration at 3TP as compared to ActLP, however all were within normal range in both conditions, supporting that only in pathological pregnancies Hsp70 is drastically increased. Conclusion Results obtained indicate that 3TP and ActLP have clinical similarities in normal pregnancies, therefore if abnormalities are found during 3TP, precautions should be taken before ActLP. PMID:21548965

  17. Image-based modeling of hemodynamics in coronary artery aneurysms caused by Kawasaki disease.

    PubMed

    Sengupta, Dibyendu; Kahn, Andrew M; Burns, Jane C; Sankaran, Sethuraman; Shadden, Shawn C; Marsden, Alison L

    2012-07-01

    Kawasaki Disease (KD) is the leading cause of acquired pediatric heart disease. A subset of KD patients develops aneurysms in the coronary arteries, leading to increased risk of thrombosis and myocardial infarction. Currently, there are limited clinical data to guide the management of these patients, and the hemodynamic effects of these aneurysms are unknown. We applied patient-specific modeling to systematically quantify hemodynamics and wall shear stress in coronary arteries with aneurysms caused by KD. We modeled the hemodynamics in the aneurysms using anatomic data obtained by multi-detector computed tomography (CT) in a 10-year-old male subject who suffered KD at age 3 years. The altered hemodynamics were compared to that of a reconstructed normal coronary anatomy using our subject as the model. Computer simulations using a robust finite element framework were used to quantify time-varying shear stresses and particle trajectories in the coronary arteries. We accounted for the cardiac contractility and the microcirculation using physiologic downstream boundary conditions. The presence of aneurysms in the proximal coronary artery leads to flow recirculation, reduced wall shear stress within the aneurysm, and high wall shear stress gradients at the neck of the aneurysm. The wall shear stress in the KD subject (2.95-3.81 dynes/sq cm) was an order of magnitude lower than the normal control model (17.10-27.15 dynes/sq cm). Particle residence times were significantly higher, taking 5 cardiac cycles to fully clear from the aneurysmal regions in the KD subject compared to only 1.3 cardiac cycles from the corresponding regions of the normal model. In this novel quantitative study of hemodynamics in coronary aneurysms caused by KD, we documented markedly abnormal flow patterns that are associated with increased risk of thrombosis. This methodology has the potential to provide further insights into the effects of aneurysms in KD and to help risk stratify patients for

  18. Tempol improves renal hemodynamics and pressure natriuresis in hyperthyroid rats.

    PubMed

    Moreno, Juan Manuel; Rodríguez Gómez, Isabel; Wangensteen, Rosemary; Alvarez-Guerra, Miriam; de Dios Luna, Juan; García-Estañ, Joaquín; Vargas, Félix

    2008-03-01

    Hyperthyroidism in rats is associated with increased oxidative stress. These animals also show abnormal renal hemodynamics and an attenuated pressure-diuresis-natriuresis (PDN) response. We analyzed the role of oxidative stress as a mediator of these alterations by examining acute effects of tempol, a superoxide dismutase mimetic. The effects of increasing bolus doses of tempol (25-150 micromol/kg) on mean arterial pressure (MAP), renal vascular resistance (RVR), and cortical (CBF) and medullary (MBF) blood flow were studied in control and thyroxine (T4)-treated rats. In another experiment, tempol was infused at 150 micromol.kg(-1).h(-1) to analyze its effects on the glomerular filtration rate (GFR) and on PDN response in these animals. Tempol dose dependently decreased MAP and RVR and increased CBF and MBF in control and T4-treated rats, but the T4 group showed a greater responsiveness to tempol in all of these variables. The highest dose of tempol decreased RVR by 13.5 +/- 2.1 and 5.5 +/- 1.2 mmHg.ml(-1).min(-1) in hyperthyroid (P < 0.01) and control rats, respectively. GFR was not changed by tempol in controls but was significantly increased in the hyperthyroid group. Tempol did not change the absolute or fractional PDN responses of controls but significantly improved those of hyperthyroid rats, although without attaining normal values. Tempol increased the slopes of the relationship between renal perfusion pressure and natriuresis (T4+tempol: 0.17 +/- 0.05; T4: 0.09 +/- 0.03 microeq.min(-1).g(-1).mmHg(-1); P < 0.05) and reduced 8-isoprostane excretion in hyperthyroid rats. These results show that antioxidant treatment with tempol improves renal hemodynamic variables and PDN response in hyperthyroid rats, indicating the participation of an increased oxidative stress in these mechanisms.

  19. 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

  20. Hemodynamic management of septic shock: is it time for "individualized goal-directed hemodynamic therapy" and for specifically targeting the microcirculation?

    PubMed

    Saugel, Bernd; Trepte, Constantin J; Heckel, Kai; Wagner, Julia Y; Reuter, Daniel A

    2015-06-01

    Septic shock is a life-threatening condition in both critically ill medical patients and surgical patients during the perioperative phase. In septic shock, specific alterations in global cardiovascular dynamics (i.e., the macrocirculation) and in the microcirculatory blood flow (i.e., the microcirculation) have been described. However, the presence and degree of microcirculatory failure are in part independent from systemic macrohemodynamic variables. Macrocirculatory and microcirculatory failure can independently induce organ dysfunction. We review current diagnostic and therapeutic approaches for the assessment and optimization of both the macrocirculation and the microcirculation in septic shock. There are various technologies for the determination of macrocirculatory hemodynamic variables. We discuss the data on early goal-directed therapy for the resuscitation of the macrocirculation. In addition, we describe the concept of "individualized goal-directed hemodynamic therapy." Technologies to assess the local microcirculation are also available. However, adequate resuscitation goals for the optimization of the microcirculation still need to be defined. At present, we are not ready to specifically monitor and target the microcirculation in clinical routine outside studies. In the future, concepts for an integrative approach for individualized hemodynamic management of the macrocirculation and in parallel the microcirculation might constitute a huge opportunity to define additional resuscitation end points in septic shock.

  1. 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.

  2. Regurgitation Hemodynamics Alone Cause Mitral Valve Remodeling Characteristic of Clinical Disease States In Vitro.

    PubMed

    Connell, Patrick S; Azimuddin, Anam F; Kim, Seulgi E; Ramirez, Fernando; Jackson, Matthew S; Little, Stephen H; Grande-Allen, K Jane

    2016-04-01

    Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5 mm displacement of papillary muscles towards the annulus), and FMR (5 mm apical, 5 mm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics.

  3. Numerical simulation of aneurysm hemodynamics

    NASA Astrophysics Data System (ADS)

    MacVicar, Stephen; Huynh, Sophia; Rossmann, Jenn

    2003-11-01

    Rupture of intracranial aneurysms is the leading cause of spontaneous subarachnoid hemorrhage, with high rates of morbidity and mortality. Numerical simulations of flow in a variety of two-dimensional and three-dimensional saccular aneurysm geometries were performed to evaluate possible sites and mechanisms for aneurysm growth and rupture. The governing equations were solved in their finite volume formulation for both steady and pulsatile flows. Recirculation zones and secondary flows were observed in aneurysms and arteries. Regions of elevated and oscillating shear stress were observed, often at the aneurysm's distal shoulder. The influence of several geometric factors, including vessel curvature, branching angle, and aneurysm shape, on flow patterns and fluid mechanical forces was studied, with the goal of assessing the risks posed by given aneurysm geometry.

  4. Hemodynamics and transient flow reversal in real deployed stents

    NASA Astrophysics Data System (ADS)

    Metcalfe, Ralph; Ionescu, Mircea

    2011-11-01

    Restenosis rates caused by neointimal hyperplasia are relatively high (~ 30 %) after stent implantation in stenosed arteries. The flow around stent struts under steady and unsteady conditions using computational hemodynamics (CHD) was studied to identify contributing factors to the formation of low and oscillating wall shear stress regions that have been shown to promote endothelial dysfunction and atherosclerotic plaque formation in arteries. Datasets of the Neuroform, BxVelocity, and Taxus stents deployed in straight polymer tubes were obtained from high resolution micro computed tomography. Finite volume CHD simulations of steady and unsteady flow with and without flow reversal were performed. Stagnation zones were noticed adjacent to the strut junctions as the flow enters and exits the stent cells. The stagnation zones were larger in the case of the stents with larger strut diameter (BxVelocity, Taxus), wider strut junctions and larger angles between the struts. Unsteady flow simulations showed enhanced flow reversal with thicker struts and large regions of recirculation flow developing inside the stent at Reynolds numbers higher than 200. It was shown that alterations in blood flow due to real stent deployment (strut prolapse, junction misalignment) cannot be captured with computer generated stent models, that stent specific geometry, and time dependent flow effects can locally alter the wall shear stress and stagnation zones.

  5. Coupling hemodynamics with vascular wall mechanics and mechanobiology to understand intracranial aneurysms

    PubMed Central

    Humphrey, J.D.

    2009-01-01

    Arteries exhibit a remarkable ability to adapt in response to sustained alterations in hemodynamic loading, to heal in response to injuries, and to compensate in response to diverse disease conditions. Nevertheless, such compensatory adaptations are limited and many vascular disorders, if untreated, lead to significant morbidity or mortality. Parallel advances in vascular biology, medical imaging, biomechanics, and computational methods promise to provide increased insight into many arterial diseases, including intracranial aneurysms. In particular, although it may be possible to identify useful clinical correlations between either the blood flow patterns within or the shape of aneurysms and their rupture-potential, our ultimate goal should be to couple studies of hemodynamics with those of wall mechanics and the underlying mechanobiology so that we can understand better the mechanisms by which aneurysms arise, enlarge, and rupture and thereby identify better methods of treatment. This paper presents one such approach to fluid-solid-growth (FSG) modeling of intracranial aneurysms. PMID:20526461

  6. 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.

  7. Hemodynamically Driven Vein Graft Remodeling: A Systems Biology Approach

    PubMed Central

    Berceli, Scott A.; Tran-Son-Tay, Roger; Garbey, Marc; Jiang, Zhihua

    2011-01-01

    Despite intense investigation over several decades to understand the mechanisms of vein graft failure, few therapeutic modalities have emerged. Emphasis using standard reductionist approaches has been focused on cataloging the components involved in the early events following vein graft implantation, but limited insight has been gained in understanding the dynamic interaction of these components. We propose that the application of systems theory offers the opportunity for significant advances in this area. Focused on modeling the dynamic relationships that define living organisms, systems biology provides the necessary tools to further our understanding of the complex series of overlapping biologic events on surgical implantation of the vein graft. Through the use of ordinary differential equation and agent-based modeling techniques, we present our ongoing efforts to define the nonlinear interactions between hemodynamics and vascular adaptation. PMID:19426605

  8. A Point Mutation in the FRNK Motif of the Potyvirus Helper Component-Protease Gene Alters Symptom Expression in Cucurbits and Elicits Protection Against the Severe Homologous Virus.

    PubMed

    Gal-On, A

    2000-05-01

    Sequence comparison had previously shown three amino acid changes in conserved motifs in the 455-amino acid sequence of the helper component-protease (HC-Pro) between a severe field strain of Zucchini yellow mosaic virus (ZYMV-NAT) and a mild field strain of ZYMV (ZYMV-WK). In this study, exchange of fragments and site-directed mutagenesis within the HC-Pro gene in an infectious clone of ZYMV enabled the effects of the mutations on symptom expression to be mapped. The substitution of Ile for Arg at position 180 in the conserved motif Phe-Arg-Asn-Lys (FRNK) of potyviruses was found to affect symptom expression. Infection of cucurbits with the engineered ZYMV (ZYMV-AG) that contained this mutation caused a dramatic symptom change from severe to mild in squash and to a symptom-free appearance in cucumber, melon, and watermelon. The Ile to Arg mutation was found to be stable, and no revertant virus was found after several passages through plants after long incubation periods. The AG strain was detected 4 days postinoculation and accumulated in cucurbits to a level and with kinetics similar to that of the wild-type ZYMV-AT strain. Cucurbit plants infected with the AG strain were protected against infection by the severe strain.

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

    PubMed

    Conde, Vanessa R; Oliveira, Pedro F; Nunes, Ana R; Rocha, Cátia S; 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.

  10. 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.

  11. Hemodynamic and thrombogenic analysis of a trileaflet polymeric valve using a fluid-structure interaction approach

    PubMed Central

    Piatti, Filippo; Sturla, Francesco; Marom, Gil; Sheriff, Jawaad; Claiborne, Thomas E.; Slepian, Marvin J.; Redaelli, Alberto; Bluestein, Danny

    2015-01-01

    Surgical valve replacement in patients with severe calcific aortic valve disease using either bioprosthetic or mechanical heart valves is still limited by structural valve deterioration for the former and thrombosis risk mandating anticoagulant therapy for the latter. Prosthetic polymeric heart valves have the potential to overcome the inherent material and design limitations of these valves, but their development is still ongoing. The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach. The FSI model replicated experimental conditions of the valve as tested in a left heart simulator. Hemodynamic parameters (transvalvular pressure gradient, flow rate, maximum velocity, and effective orifice area) were compared to assess the validity of the FSI model. The thrombogenic footprint of the polymeric valve was evaluated using a Lagrangian approach to calculate the stress accumulation (SA) values along multiple platelet trajectories and their statistical distribution. In the commissural regions, platelets were exposed to the highest SA values because of highest stress levels combined with local reverse flow patterns and vortices. Stress-loading waveforms from representative trajectories in regions of interest were emulated in our Hemodynamic Shearing Device (HSD). Platelet activity was measured using our platelet activation state (PAS) assay and the results confirmed the higher thrombogenic potential of the commissural hotspots. In conclusion, the proposed method provides an in depth analysis of the hemodynamic and thrombogenic performance of the polymer valve prototype and identifies locations for further design optimization. PMID:26329461

  12. 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.

  13. [Second Clinical Consensus of the Ibero-American Society of Neonatology: hemodynamic management of newborns].

    PubMed

    Golombek, Sergio G; Fariña, Diana; Sola, Augusto; Baquero, Hernando; Cabañas, Fernando; Dominguez, Fernando; Fajardo, Carlos; Goldsmit, Gustavo S; Flores, Gabriel Lara; Lee, Mario; Varela, Lourdes Lemus; Mariani, Gonzalo; Miura, Ernani; Pérez, Jose Maria; Zambosco, Guillermo; Pellicer, Adelina; Bancalari, Eduardo

    2011-04-01

    This study reports on the process and results of the Second Clinical Consensus of the Ibero-American Society of Neonatology. Eighty neonatologists from 23 countries were invited to collaborate and participate in the event. Several questions of clinical-physiological importance in the hemodynamic management of newborns were addressed. Participants were divided into groups to facilitate interaction and teamwork, with instructions to respond to three to five questions by analyzing the literature and local factors. Meeting in Mar del Plata, Argentina, the Consensus Group served as a form for various presentations and discussions. In all, 54 neonatologists from 21 countries attended, with the objective of reaching a consensus on such matters as concepts and definitions of hemodynamic instability, the physiopathology of hemodynamic compromise, recommended therapy strategies, and hemodynamic monitoring. It is hoped that this international experience will serve as a useful initiative for future consensus building and reduction of the existing disparities among the countries of the Region in terms of treatment and outcomes.

  14. [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.

  15. Pathologic findings in adenosine deaminase deficient-severe combined immunodeficiency. II. Thymus, spleen, lymph node, and gastrointestinal tract lymphoid tissue alterations.

    PubMed Central

    Ratech, H.; Hirschhorn, R.; Greco, M. A.

    1989-01-01

    Eight autopsies of patients with adenosine deaminase deficient-severe combined immunodeficiency disease (ADA-SCID) were reviewed with special emphasis on the lymphoid tissues. The thymus histology in five cases was remarkably uniform, whether or not prior ADA enzyme replacement or immunologic reconstitution therapy had been administered. Lymph nodes and spleens in all cases examined showed a residual nonlymphoid architectural framework corresponding to usual T and B cell zones found in normals. The development of an extranodal, monoclonal IgA lambda B cell immunoblastic lymphoma as a terminal event in one patient after several years of successful ADA enzyme replacement therapy through multiple red blood cell transfusions is described. In another patient with long-term ADA enzyme replacement, a terminal autoimmune hemolytic anemia developed. Autopsy revealed severe deposits of iron in the B cell zones of the lymph nodes, which is an unusual location. In addition, iron deposits outlined the splenic trabeculae, as well as the ring fibers and bridging fibers of the splenic sinuses. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 PMID:2596574

  16. Impact of Therapeutic Plasma Exchange on Hemodynamic Parameters in Medical Intensive Care Unit Patients: An Observational Study.

    PubMed

    Lahmer, Tobias; Messer, Marlena; Schnappauf, Christopher; Rasch, Sebastian; Fekecs, Lisa; Beitz, Analena; Eser, Stefan; Schmid, Roland M; Huber, Wolfgang

    2017-02-01

    Therapeutic plasma exchange (TPE) is an extracorporeal treatment with reported beneficial as well as detrimental effects on circulation. However, there is a lack of data using advanced hemodynamic monitoring during TPE. Therefore, we investigated the effects of TPE on hemodynamic parameters derived from transpulmonary thermodilution (TPTD) as well as the risk for transfusion-related acute lung injury (TRALI). We compared hemodynamic parameters obtained before and after a total of 30 sessions of TPE treatment in 10 intensive care unit patients. Among standard hemodynamic parameters, heart rate (P < 0.012) and systolic blood pressure (P < 0.008) significantly increase, whereas neither mean arterial pressure nor diastolic blood pressure was altered after TPE. The TPTD-derived cardiac function parameters, cardiac index (CI; P = 0.035), cardiac power index (CPI; P = 0.008), global ejection fraction (GEF; P = 0.002), and stroke volume index (SVI; P = 0.014), were significantly higher after TPE. Furthermore, systemic vascular index significantly increased (P < 0.042). Among the cardiac preload parameters, central venous pressure was significantly lower after TPE (P < 0.001), while the global end-diastolic volume index (GEDVI) did not change. Contractility marker dPmax did not change. Finally, TPE application did not significantly alter the pulmonary hydration and permeability parameters, extravascular lung water index (EVLWI) and pulmonary vascular permeability index. Vasopressor dose was not statistically significantly altered. Considering increases in SVI, CI, GEF, and CPI and stable values for GEDVI, EVLWI, and dPmax, our data do not give any hint for hemodynamic impairment or TRALI.

  17. Depletion of Foxp3+ regulatory T cells increases severity of mechanical allodynia and significantly alters systemic cytokine levels following peripheral nerve injury.

    PubMed

    Lees, Justin G; Duffy, Samuel S; Perera, Chamini J; Moalem-Taylor, Gila

    2015-02-01

    Neuropathic pain is a debilitating condition caused by damage to the somatosensory nervous system, such as peripheral nerve injury. The immune system, and in particular the adaptive T cell response, plays a key role in mediating such pain. Regulatory T (Treg) cells are a small subpopulation of inhibitory T cells that prevent autoimmunity, limit immunopathology and maintain immune homeostasis. Here, we investigated the effects of conditional depletion of Treg cells on mechanical allodynia and serum cytokines in mice with chronic constriction injury (CCI) of the sciatic nerve, an animal model of neuropathic pain. We demonstrate that CCI induced the infiltration of small numbers of Treg cells within effected neuronal tissue. Utilising the transgenic DEREG (DEpletion of REGulatory T cells) mice, we confirmed effective depletion of Foxp3+ Treg cells by diphtheria toxin injections. Following CCI we observed a transient, though significant, increase in pain hypersensitivity for Treg-depleted DEREG mice compared to non-Treg-depleted mice. Analysis of systemic cytokine levels demonstrated significant changes in serum cytokine expression profiles. In particular, we observed significant increases in systemic concentration of RANTES, IL-2 and IL-5, and significant decreases in IL-12 and IFN-γ in nerve-injured Treg-depleted DEREG mice. Further analysis indicated a substantial increase in the serum concentration of IL-12p40 as a direct result of Treg cell depletion. These results suggest that depletion of Foxp3+ Treg cells promote nerve injury-induced pain hypersensitivity, partially by inducing altered systemic concentrations of cytokines, which may act to regulate neuropathic pain.

  18. 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. PMID:27630562

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

    PubMed

    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 BRCA1(null) 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.

  20. 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

  1. Altered Brain Functional Activity in Infants with Congenital Bilateral Severe Sensorineural Hearing Loss: A Resting-State Functional MRI Study under Sedation

    PubMed Central

    Che, Jing; Li, Qiang; Chai, Chao; Zheng, Meizhu; Shen, Wen

    2017-01-01

    Early hearing deprivation could affect the development of auditory, language, and vision ability. Insufficient or no stimulation of the auditory cortex during the sensitive periods of plasticity could affect the function of hearing, language, and vision development. Twenty-three infants with congenital severe sensorineural hearing loss (CSSHL) and 17 age and sex matched normal hearing subjects were recruited. The amplitude of low frequency fluctuations (ALFF) and regional homogeneity (ReHo) of the auditory, language, and vision related brain areas were compared between deaf infants and normal subjects. Compared with normal hearing subjects, decreased ALFF and ReHo were observed in auditory and language-related cortex. Increased ALFF and ReHo were observed in vision related cortex, which suggest that hearing and language function were impaired and vision function was enhanced due to the loss of hearing. ALFF of left Brodmann area 45 (BA45) was negatively correlated with deaf duration in infants with CSSHL. ALFF of right BA39 was positively correlated with deaf duration in infants with CSSHL. In conclusion, ALFF and ReHo can reflect the abnormal brain function in language, auditory, and visual information processing in infants with CSSHL. This demonstrates that the development of auditory, language, and vision processing function has been affected by congenital severe sensorineural hearing loss before 4 years of age. PMID:28255465

  2. Short-term oral administration of several manganese compounds in mice: Physiological and behavioral alterations caused by different forms of manganese

    SciTech Connect

    Komura, Junko; Sakamoto, Michiko )

    1991-06-01

    In Kanazawa, Japan, air pollution from a Mn treatment factory was found to affect local junior high school students, who showed reduced respiratory function relative to their exposure to Mn. The use of Mn as an antiknock ingredient in automobile fuels has recently been introduced, placing the general population at risk of chronic low-level exposure. There are few animal studies on the effects of compounds other than manganese chloride (MnCl{sub 2}). In the case of environmental pollution by Mn, the differing physiological effects of the various chemical forms of Mn must be considered. The present study therefore examined the differences in the effects of several Mn compounds on the physiology and behavior of mice by short-term oral administration.

  3. Calpain Protects the Heart from Hemodynamic Stress*

    PubMed Central

    Taneike, Manabu; Mizote, Isamu; Morita, Takashi; Watanabe, Tetsuya; Hikoso, Shungo; Yamaguchi, Osamu; Takeda, Toshihiro; Oka, Takafumi; Tamai, Takahito; Oyabu, Jota; Murakawa, Tomokazu; Nakayama, Hiroyuki; Nishida, Kazuhiko; Takeda, Junji; Mochizuki, Naoki; Komuro, Issei; Otsu, Kinya

    2011-01-01

    Calpains make up a family of Ca2+-dependent intracellular cysteine proteases that include ubiquitously expressed μ- and m-calpains. Both are heterodimers consisting of a distinct large catalytic subunit (calpain 1 for μ-calpain and calpain 2 for m-calpain) and a common regulatory subunit (calpain 4). The physiological roles of calpain remain unclear in the organs, including the heart, but it has been suggested that calpain is activated by Ca2+ overload in diseased hearts, resulting in cardiac dysfunction. In this study, cardiac-specific calpain 4-deficient mice were generated to elucidate the role of calpain in the heart in response to hemodynamic stress. Cardiac-specific deletion of calpain 4 resulted in decreased protein levels of calpains 1 and 2 and showed no cardiac phenotypes under base-line conditions but caused left ventricle dilatation, contractile dysfunction, and heart failure with interstitial fibrosis 1 week after pressure overload. Pressure-overloaded calpain 4-deficient hearts took up a membrane-impermeant dye, Evans blue, indicating plasma membrane disruption. Membrane repair assays using a two-photon laser-scanning microscope revealed that calpain 4-deficient cardiomyocytes failed to reseal a plasma membrane that had been disrupted by laser irradiation. Thus, the data indicate that calpain protects the heart from hemodynamic stresses, such as pressure overload. PMID:21795695

  4. 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.

  5. 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

  6. Sustained low-efficiency dialysis in septic shock: Hemodynamic tolerability and efficacy

    PubMed Central

    Mishra, Shakti Bedanta; Singh, Ratender Kumar; Baronia, Arvind Kumar; Poddar, Banani; Azim, Afzal; Gurjar, Mohan

    2016-01-01

    Aim of the Study: Acute kidney injury (AKI) in septic shock has poor outcomes. Sustained low-efficiency dialysis (SLED) is increasingly replacing continuous renal replacement therapy as the preferred modality in Intensive Care Units (ICUs). However, the essential aspects of hemodynamic tolerability and efficacy of SLED in septic shock AKI has been minimally studied. Patients and Methods: We describe hemodynamic tolerability using modified vasopressor index (VI) and vasopressor dependency (VD) and efficacy using a combination of Kt/v, correction of acidosis, electrolyte, and fluid overload. Adult ICU patients of septic shock in AKI requiring SLED were included in this study. Results: One hundred and twenty-four patients of septic shock AKI requiring SLED were enrolled in the study. There were 74 nonsurvivors (NSs). Approximately, 56% (278/498) of the sessions in which vasopressors were required were studied. Metabolic acidosis (49%) was the predominant indication for the initiation of SLED in these patients. Baseline characteristics between survivors and NSs were comparable, except for age, severity scores, AKI stage, and coexisting illness. VI and VD prior to the initiation of SLED and delta VI and VD during SLED were significantly higher in NSs. Hemodynamic tolerability and efficacy of SLED was achievable only at lower vasopressor doses. Conclusion: VI, VD, and combination of Kt/v together with correction of acidosis, electrolyte, and fluid overload can be used to describe hemodynamic tolerability and efficacy of SLED in septic shock AKI. However, at higher vasopressor doses in septic shock, hemodynamic tolerability and efficacy of SLED requires further evidence. PMID:28149027

  7. Arterial stiffness, central hemodynamics, and cardiovascular risk in hypertension

    PubMed Central

    Palatini, Paolo; Casiglia, Edoardo; Gąsowski, Jerzy; Głuszek, Jerzy; Jankowski, Piotr; Narkiewicz, Krzysztof; Saladini, Francesca; Stolarz-Skrzypek, Katarzyna; Tikhonoff, Valérie; Van Bortel, Luc; Wojciechowska, Wiktoria; Kawecka-Jaszcz, Kalina

    2011-01-01

    This review summarizes several scientific contributions at the recent Satellite Symposium of the European Society of Hypertension, held in Milan, Italy. Arterial stiffening and its hemodynamic consequences can be easily and reliably measured using a range of noninvasive techniques. However, like blood pressure (BP) measurements, arterial stiffness should be measured carefully under standardized patient conditions. Carotid-femoral pulse wave velocity has been proposed as the gold standard for arterial stiffness measurement and is a well recognized predictor of adverse cardiovascular outcome. Systolic BP and pulse pressure in the ascending aorta may be lower than pressures measured in the upper limb, especially in young individuals. A number of studies suggest closer correlation of end-organ damage with central BP than with peripheral BP, and central BP may provide additional prognostic information regarding cardiovascular risk. Moreover, BP-lowering drugs can have differential effects on central aortic pressures and hemodynamics compared with brachial BP. This may explain the greater beneficial effect provided by newer antihypertensive drugs beyond peripheral BP reduction. Although many methodological problems still hinder the wide clinical application of parameters of arterial stiffness, these will likely contribute to cardiovascular assessment and management in future clinical practice. Each of the abovementioned parameters reflects a different characteristic of the atherosclerotic process, involving functional and/or morphological changes in the vessel wall. Therefore, acquiring simultaneous measurements of different parameters of vascular function and structure could theoretically enhance the power to improve risk stratification. Continuous technological effort is necessary to refine our methods of investigation in order to detect early arterial abnormalities. Arterial stiffness and its consequences represent the great challenge of the twenty-first century for

  8. Hemodynamic changes by drug interaction of adrenaline with chlorpromazine.

    PubMed

    Higuchi, Hitoshi; Yabuki, Akiko; Ishii-Maruhama, Minako; Tomoyasu, Yumiko; Maeda, Shigeru; Miyawaki, Takuya

    2014-01-01

    Adrenaline (epinephrine) is included in dental local anesthesia for the purpose of vasoconstriction. In Japan, adrenaline is contraindicated for use in patients receiving antipsychotic therapy, because the combination of adrenaline and an antipsychotic is considered to cause severe hypotension; however, there is insufficient evidence supporting this claim. The purpose of the present study was to clarify the changes in hemodynamics caused by drug interaction between adrenaline and an antipsychotic and to evaluate the safety of the combined use of adrenaline and an antipsychotic in an animal study. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital. A catheter was inserted into the femoral artery to measure blood pressure and pulse rate. Rats were pretreated by intraperitoneal injection of chlorpromazine or chlorpromazine and propranolol, and after 20 minutes, saline or 1 of 3 different doses of adrenaline was administered by intraperitoneal injection. Changes in the ratio of mean arterial blood pressure and pulse rate were measured after the injection of adrenaline. Significant hypotension and tachycardia were observed after the injection of adrenaline in the chlorpromazine-pretreated rats. These effects were in a dose-dependent manner, and 100 μg/kg adrenaline induced significant hemodynamic changes. Furthermore, in the chlorpromazine and propranolol-pretreated rats, modest hypertension was induced by adrenaline, but hypotension and tachycardia were not significantly shown. Hypotension was caused by a drug interaction between adrenaline and chlorpromazine through the activation of the β-adrenergic receptor and showed a dose-dependent effect. Low-dose adrenaline similar to what might be used in human dental treatment did not result in a significant homodynamic change.

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

    PubMed Central

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

    2009-01-01

    To investigate whether or not a successful aneurysm treatment procedure can subject a 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. Prior to treatment, the aneurysm at systole is filled with a periodic train of vortex tubes, which form at the aneurysm neck and advect upwards into the dome. Following the treatment procedure however, the motion of the vortex train is inhibited by the aneurysm filling material, which confines the vortex tubes to the region beneath the aneurysm neck. Analysis of the post-treatment flow field indicates that the impingement of the basilar artery flow upon the treated aneurysm neck and the close proximity of a vortex tube to the parent artery wall increase the maximum wall shear stresses to values approximately equal to 50 Pa at systole. Calculation of the time-averaged wall shear stresses indicates that there is a 1.4 × 9 10−7 m2 area on the parent artery exposed to wall shear stresses greater than 37.9 Pa, a value shown by Fry [Circ. Res. 22(2):165–197, 1968] to cause severe damage to the endothelial cells that line the artery wall. The results of this study demonstrate that it is possible for a treatment procedure, which successfully isolates the aneurysm from the circulation and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the artery wall. PMID:18629647

  10. Hemodynamic Effect of Laser Therapy in Spontaneously Hypertensive Rats

    PubMed Central

    Tomimura, Suely; Silva, Bianca Passos Assumpção; Sanches, Iris Callado; Canal, Marina; Consolim-Colombo, Fernanda; Conti, Felipe Fernandes; Angelis, Katia De; Chavantes, Maria Cristina

    2014-01-01

    Systemic arterial hypertension (SAH) is considered to be the greatest risk factor for the development of neuro-cardiovascular pathologies, thus constituting a severe Public Health issue in the world. The Low-Level Laser Therapy (LLLT), or laser therapy, activates components of the cellular structure, therefore converting luminous energy into photochemical energy and leading to biophysical and biochemical reactions in the mitochondrial respiratory chain. The LLLT promotes cellular and tissue photobiomodulation by means of changes in metabolism, leading to molecular, cellular and systemic changes. The objective of this study was to analyze the action of low-level laser in the hemodynamic modulation of spontaneously hypertensive rats, in the long term. Animals (n = 16) were randomly divided into the Laser Group (n = 8), which received three weekly LLLT irradiations for seven weeks, and into the Sham Group (n = 8), which received three weekly simulations of laser for seven weeks, accounting for 21 applications in each group. After seven weeks, animals were cannulated by the implantation of a catheter in the left carotid artery. On the following day, the systemic arterial pressure was recorded. The Laser Group showed reduced levels of mean blood pressure, with statistically significant reduction (169 ± 4 mmHg* vs. 182 ± 4 mmHg from the Sham Group) and reduced levels of diastolic pressure (143 ± 4 mmHg* vs. 157 ± 3 mmHg from the Sham Group), revealing a 13 and 14 mmHg decrease, respectively. Besides, there was a concomitant important decline in heart rate (312 ± 14 bpm vs. 361 ± 13 bpm from the Sham Group). Therefore, laser therapy was able to produce hemodynamic changes, thus reducing pressure levels in spontaneously hypertensive rats. PMID:25211315

  11. Advanced Hemodynamic Management in Patients with Septic Shock

    PubMed Central

    Huber, Wolfgang; Nierhaus, Axel; Kluge, Stefan; Reuter, Daniel A.; Wagner, Julia Y.

    2016-01-01

    In patients with sepsis and septic shock, the hemodynamic management in both early and later phases of these “organ dysfunction syndromes” is a key therapeutic component. It needs, however, to be differentiated between “early goal-directed therapy” (EGDT) as proposed for the first 6 hours of emergency department treatment by Rivers et al. in 2001 and “hemodynamic management” using advanced hemodynamic monitoring in the intensive care unit (ICU). Recent large trials demonstrated that nowadays protocolized EGDT does not seem to be superior to “usual care” in terms of a reduction in mortality in emergency department patients with early identified septic shock who promptly receive antibiotic therapy and fluid resuscitation. “Hemodynamic management” comprises (a) making the diagnosis of septic shock as one differential diagnosis of circulatory shock, (b) assessing the hemodynamic status including the identification of therapeutic conflicts, and (c) guiding therapeutic interventions. We propose two algorithms for hemodynamic management using transpulmonary thermodilution-derived variables aiming to optimize the cardiocirculatory and pulmonary status in adult ICU patients with septic shock. The complexity and heterogeneity of patients with septic shock implies that individualized approaches for hemodynamic management are mandatory. Defining individual hemodynamic target values for patients with septic shock in different phases of the disease must be the focus of future studies. PMID:27703980

  12. Effect of Hemodynamics on Outcome of Subtotally Occluded Paraclinoid Aneurysms after Stent-Assisted Coil Embolization

    PubMed Central

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

    2016-01-01

    BACKGROUND and OBJECTIVE Endovascular treatment of paraclinoid aneurysms is preferred in clinical practice. Flow alterations caused by stents and coils may affect treatment outcome. Our aim was to assess hemodynamic changes following stent-assisted coil embolization in subtotally embolized paraclinoid aneurysms with residual necks that were predisposed to recanalization. METHODS We studied 27 paraclinoid aneurysms (seven recanalized and 20 stable) treated with coils and Enterprise™ stents. Computational fluid dynamics simulations were performed on patient-specific aneurysm geometries using virtual stenting and porous media technology. RESULTS After stent placement in 27 cases, aneurysm flow velocity decreased significantly, gradually increasing from the neck plane (11.9%), to the residual neck (12.3%), to the aneurysm dome (16.3%). Subsequent coil embolization was performed after stent placement and the hemodynamic factors decreased further and significantly at all aneurysm regions except the neck plane. Compared between recanalized and stable cases, univariate analysis showed no significant differences in any parameter before treatment. After stent-assisted coiling, only the reduction in area-averaged velocity at the neck plane differed significantly between recanalized (8.1%) and stable cases (20.5%) (p=0.016). CONCLUSION Aneurysm flow velocity can be significantly decreased by stent placement and coil embolization. However, hemodynamics at the aneurysm neck plane was less sensitive to coils. Significant reduction in flow velocity at the neck plane may be an important factor in preventing recanalization of paraclinoid aneurysms after subtotal stent-assisted coil embolization. PMID:26610731

  13. Assessment of Hemodynamic Conditions in the Aorta Following Root Replacement with Composite Valve-Conduit Graft.

    PubMed

    Cheng, Zhuo; Kidher, Emaddin; Jarral, Omar A; O'Regan, Declan P; Wood, Nigel B; Athanasiou, Thanos; Xu, Xiao Yun

    2016-05-01

    This paper presents the analysis of detailed hemodynamics in the aortas of four patients following replacement with a composite bio-prosthetic valve-conduit. Magnetic resonance image-based computational models were set up for each patient with boundary conditions comprising subject-specific three-dimensional inflow velocity profiles at the aortic root and central pressure waveform at the model outlet. Two normal subjects were also included for comparison. The purpose of the study was to investigate the effects of the valve-conduit on flow in the proximal and distal aorta. The results suggested that following the composite valve-conduit implantation, the vortical flow structure and hemodynamic parameters in the aorta were altered, with slightly reduced helical flow index, elevated wall shear stress and higher non-uniformity in wall shear compared to normal aortas. Inter-individual analysis revealed different hemodynamic conditions among the patients depending on the conduit configuration in the ascending aorta, which is a key factor in determining post-operative aortic flow. Introducing a natural curvature in the conduit to create a smooth transition between the conduit and native aorta may help prevent the occurrence of retrograde and recirculating flow in the aortic arch, which is particularly important when a large portion or the entire ascending aorta needs to be replaced.

  14. 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.

  15. 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.

  16. 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.

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

    PubMed

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

    2008-08-01

    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 Pco(2) 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.

  18. Altered intrinsic regional brain activity in male patients with severe obstructive sleep apnea: a resting-state functional magnetic resonance imaging study

    PubMed Central

    Peng, De-Chang; Dai, Xi-Jian; Gong, Hong-Han; Li, Hai-Jun; Nie, Xiao; Zhang, Wei

    2014-01-01

    Background Previous studies have demonstrated that obstructive sleep apnea (OSA) is associated with abnormal brain structural deficits. However, little is known about the changes in local synchronization of spontaneous activity in patients with OSA. The primary aim of the present study was to investigate spontaneous brain activity in patients with OSA compared with good sleepers (GSs) using regional homogeneity (ReHo) analysis based on resting-state functional magnetic resonance imaging (MRI). Methods Twenty-five untreated male patients with severe OSA and 25 male GSs matched for age and years of education were included in this study. The ReHo method was calculated to assess the strength of local signal synchrony and was compared between the two groups. The observed mean ReHo values were entered into Statistical Package for the Social Sciences software to assess their correlation with behavioral performance. Results Compared with GSs, patients with OSA showed significantly lower ReHo in the right medial frontal gyrus (BA11), right superior frontal gyrus (BA10), right cluster of the precuneus and angular gyrus (BA39), and left superior parietal lobule (BA7), and higher ReHo in the right posterior lobe of the cerebellum, right cingulate gyrus (BA23), and bilateral cluster covering the lentiform nucleus, putamen, and insula (BA13). The lower mean ReHo value in the right cluster of the precuneus and angular gyrus had a significant negative correlation with sleep time (r=−0.430, P=0.032), and higher ReHo in the right posterior lobe of the cerebellum showed a significant positive correlation with stage 3 sleep (r=0.458, P=0.021) and in the right cingulate gyrus showed a significant positive correlation with percent rapid eye movement sleep (r=0.405, P=0.045). Conclusion Patients with OSA showed significant regional spontaneous activity deficits in default mode network areas. The ReHo method is a useful noninvasive imaging tool for detection of early changes in cerebral

  19. 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

  20. 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

  1. [Hemodynamic adaptations in proximal cerebrovascular occlusion].

    PubMed

    De Ley, G

    1990-01-01

    In order to gain more insight into the pathophysiology of extracerebral cerebrovascular occlusion, the cerebral hemodynamic behaviour after uni- or bilateral carotid occlusion was investigated. In Wistar rats, acute occlusion of one common carotid artery leads to a moderate bilateral lowering of the resting hemispheric brain blood flow; no interhemispheric perfusion asymmetry is observed. During hypercapnia, however, a manyfold increase of the hemispheric blood flow is seen at the intact side, whereas blood flow increase at the side of the occlusion is suppressed indicating that the cerebrovascular reserve at the side of the occlusion is largely used to preserve resting hemispheric perfusion. During the days (1, 5, 15 and 30) following the occlusion, resting hemispheric blood flow is progressively restored rather rapidly (bilateral normalization on the fifth day) whereas restoration of the cerebrovascular reserve (hemispheric blood flow increase in hypercapnia) proceeds more slowly and a nearly normal hypercapnic response is reached on day thirty. Spontaneously Hypertensive Rats (SHR) show structural abnormalities of their blood vessels during the development of hypertension, leading to impaired adaptation possibilities of the cerebral vasculature after unilateral common carotid occlusion. This is indicated by the striking comparability of the compensation of hemispheric cerebral blood flow (in normo- and hypercapnia) of SH rats five days after unilateral carotid occlusion with the cerebral hemodynamic status of normotensive animals already seen 24 hours after the same occlusion. Consecutive bilateral common carotid occlusion shows that survival rate increases by increasing the interval between both occlusions. This survival relation is much more unfavorable in SH rats. The parallelism between the restoration of the measured CO2-reactivity of the blood flow in the involved hemisphere after unilateral carotid occlusion and the evolution of survival rate after

  2. Cardioselectivity, kinetics, hemodynamics, and metabolic effects of xamoterol.

    PubMed

    Jennings, G; Bobik, A; Oddie, C; Restall, R

    1984-05-01

    Xamoterol is a new orally active partial beta-adrenoceptor agonist. Its kinetics, hemodynamic and metabolic effects, and cardioselectivity were investigated in eight normal subjects. Plasma xamoterol concentrations after 100 micrograms/kg iv declined biexponentially over 8 hr and t 1/2 beta averaged 2.6 hr. Resting heart rate (HR) increased slightly in the supine position but was unchanged on sitting. Systolic blood pressure (SBP) rose by 5 to 10 mm Hg and cardiac index (CI) rose 15% to 20%. Both parameters were above control values 6 hr after dosing, when plasma xamoterol concentrations had fallen to about 10 ng/ml. There were no changes in diastolic or mean arterial pressure (MAP). During graded exercise the effects of xamoterol on HR and SBP were the reverse of those at rest, with lowering of exercise HR and SBP at higher work loads. CI during exercise was not altered by xamoterol. Doses of xamoterol were calculated from the kinetic data to give plasma concentrations of 100, 200, 400, and 800 ng/ml. HR and blood pressure effects at each xamoterol level were compared before and after inhibition of cardiovascular reflexes with prazosin, atropine, and clonidine. Hemodynamic effects of xamoterol and isoproterenol were compared. Before autonomic block xamoterol increased HR by 10 bpm and MAP by 7 mm Hg at the highest dose. After autonomic block there was a 200% to 300% rise in HR at each dose and MAP still rose. The rise in MAP after block could be entirely accounted for by a 23% increase in CI because total peripheral resistance did not change. The effects of isoproterenol after autonomic block were a rise in HR and a fall in MAP. Metabolic responses to xamoterol were measured at the four dose levels. There was a dose-related increase in nonesterified fatty acids and a fall in plasma lactate levels but no changes in plasma renin activity or blood glucose. Results suggest that xamoterol is a cardioselective partial beta-adrenoceptor agonist in man.

  3. Flow imaging and computing: large artery hemodynamics.

    PubMed

    Steinman, David A; Taylor, Charles A

    2005-12-01

    The objective of our session at the International Bio-Fluid Mechanics Symposium and Workshop was at the International Bio-Fluid Mechanics Symposium and Workshop to review the state-of-the-art in, and identify future directions for, imaging and computational modeling of blood flow in the large arteries and the microcirculation. Naturally, talks in other sessions of the workshop overlapped this broad topic, and so here we summarize progress within the last decade in terms of the technical development and application of flow imaging and computing, rather than the knowledge derived from specific studies. We then briefly discuss ways in these tools may be extended, and their application broadened, in the next decade. Furthermore, owing to the conceptual division between the hemodynamics of large arteries, and those within the microcirculation, we review these regimes separately: The former here by Steinman and Taylor; and the latter in a separate paper by Cristini.

  4. Hemodynamic traveling waves in human visual cortex.

    PubMed

    Aquino, Kevin M; Schira, Mark M; Robinson, P A; Drysdale, Peter M; Breakspear, Michael

    2012-01-01

    Functional MRI (fMRI) experiments rely on precise characterization of the blood oxygen level dependent (BOLD) signal. As the spatial resolution of fMRI reaches the sub-millimeter range, the need for quantitative modelling of spatiotemporal properties of this hemodynamic signal has become pressing. Here, we find that a detailed physiologically-based model of spatiotemporal BOLD responses predicts traveling waves with velocities and spatial ranges in empirically observable ranges. Two measurable parameters, related to physiology, characterize these waves: wave velocity and damping rate. To test these predictions, high-resolution fMRI data are acquired from subjects viewing discrete visual stimuli. Predictions and experiment show strong agreement, in particular confirming BOLD waves propagating for at least 5-10 mm across the cortical surface at speeds of 2-12 mm s-1. These observations enable fundamentally new approaches to fMRI analysis, crucial for fMRI data acquired at high spatial resolution.

  5. 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

  6. 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.

  7. 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.

  8. Focused assessment with sonography for trauma (FAST) versus multidetector computed tomography in hemodynamically stable emergency patients.

    PubMed

    Fornell Pérez, R

    2017-02-10

    This critically appraised topic (CAT) study aims to evaluate the quality and extent of the scientific evidence that supports the use of focused assessment with sonography for trauma (FAST) versus multidetector computed tomography (MDCT) in hemodynamically stable trauma patients in the emergency room. An efficient search of the literature yielded several recent articles with a high level of evidence. The CAT study concludes that FAST is an acceptable initial imaging test in hemodynamically stable patients, although its performance is limited in certain circumstances. The decision whether to use MDCT should be determined by evaluating the patient's degree of instability and the distance to the MDCT scanner. Nevertheless, few articles address the question of the distance to MDCT scanners in emergency departments.

  9. Hemodynamic assessment of pre- and post-operative aortic coarctation from MRI.

    PubMed

    Ralovich, Kristóf; Itu, Lucian; Mihalef, Viorel; Sharma, Puneet; Ionasec, Razvan; Vitanovski, Dime; Krawtschuk, Waldemar; Everett, Allen; Ringel, Richard; Navab, Nassir; Comaniciu, Dorin

    2012-01-01

    Coarctation of the aorta (CoA), is a congenital defect characterized by a severe narrowing of the aorta, usually distal to the aortic arch. The treatment options include surgical repair, stent implantation, and balloon angioplasty. In order to evaluate the physiological significance of the pre-operative coarctation and to assess the post-operative results, the hemodynamic analysis is usually performed by measuring the pressure gradient (deltaP) across the coarctation site via invasive cardiac catheterization. The measure of success is reduction of the (deltaP > 20 mmHg) systolic blood pressure gradient. In this paper, we propose a non-invasive method based on Computational Fluid Dynamics and MR imaging to estimate the pre- and post-operative hemodynamics for both native and recurrent coarctation patients. High correlation of our results and catheter measurements is shown on corresponding pre- and post-operative examination of 5 CoA patients.

  10. Perioperative hemodynamic instability in patients undergoing laparoscopic adrenalectomy for pheochromocytoma

    PubMed Central

    Pisarska, Magdalena; Budzyński, Andrzej

    2016-01-01

    Perioperative hemodynamic instability still remains the biggest surgical and anesthetic challenge in surgery for pheochromocytoma. The aim of this review was to discuss pre-, intra- and postoperative factors that may impact on hemodynamic condition of a patient. It describes patients’ preparation with appropriate medication, principles of surgical technique as well as risk factors for development of hemodynamic instability in postoperative period. Currently the gold standard in the treatment of pheochromocytoma is preoperative use of alpha-blockers and laparoscopic surgery. This approach allowed improving outcomes by lowering both mortality and morbidity. PMID:27867865

  11. Invasive hemodynamics of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade.

    PubMed

    Sorajja, Paul

    2011-05-01

    Cardiac catheterization historically has been the principal diagnostic modality for the evaluation of constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade. In many instances, the hemodynamic consequences of these disorders can be accurately delineated with non-invasive methods. However, cardiac catheterization should be considered when there is a discrepancy between the clinical and non-invasive imaging data, and particularly may be required for the evaluation of patients with complex hemodynamic disorders. This report describes the methods and clinical utility of invasive hemodynamic catheterization for the evaluation of constriction, restriction, and cardiac tamponade.

  12. 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.

  13. 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

  14. Inhibition of endoplasmic reticulum-resident glucosidases impairs severe acute respiratory syndrome coronavirus and human coronavirus NL63 spike protein-mediated entry by altering the glycan processing of angiotensin I-converting enzyme 2.

    PubMed

    Zhao, Xuesen; Guo, Fang; Comunale, Mary Ann; Mehta, Anand; Sehgal, Mohit; Jain, Pooja; Cuconati, Andrea; Lin, Hanxin; Block, Timothy M; Chang, Jinhong; Guo, Ju-Tao

    2015-01-01

    Endoplasmic reticulum (ER)-resident glucosidases I and II sequentially trim the three terminal glucose moieties on the N-linked glycans attached to nascent glycoproteins. These reactions are the first steps of N-linked glycan processing and are essential for proper folding and function of many glycoproteins. Because most of the viral envelope glycoproteins contain N-linked glycans, inhibition of ER glucosidases with derivatives of 1-deoxynojirimycin, i.e., iminosugars, efficiently disrupts the morphogenesis of a broad spectrum of enveloped viruses. However, like viral envelope proteins, the cellular receptors of many viruses are also glycoproteins. It is therefore possible that inhibition of ER glucosidases not only compromises virion production but also disrupts expression and function of viral receptors and thus inhibits virus entry into host cells. Indeed, we demonstrate here that iminosugar treatment altered the N-linked glycan structure of angiotensin I-converting enzyme 2 (ACE2), which did not affect its expression on the cell surface or its binding of the severe acute respiratory syndrome coronavirus (SARS-CoV) spike glycoprotein. However, alteration of N-linked glycans of ACE2 impaired its ability to support the transduction of SARS-CoV and human coronavirus NL63 (HCoV-NL63) spike glycoprotein-pseudotyped lentiviral particles by disruption of the viral envelope protein-triggered membrane fusion. Hence, in addition to reducing the production of infectious virions, inhibition of ER glucosidases also impairs the entry of selected viruses via a post-receptor-binding mechanism.

  15. 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.

  16. Hemodynamic changes in patients with extracorporeal membrane oxygenation (ECMO) demonstrated by contrast-enhanced CT examinations - implications for image acquisition technique.

    PubMed

    Lambert, Lukas; Grus, Tomas; Balik, Martin; Fichtl, Jaromir; Kavan, Jan; Belohlavek, Jan

    2017-04-01

    Extracorporeal membrane oxygenation (ECMO) is an established tool for respiratory and circulatory support. In computed tomography, altered hemodynamics in ECMO patients requires special considerations and handling in contrast injection and its timing. In this article, we demonstrate changes in hemodynamics in ECMO patients captured on contrast-enhanced CT examinations and pitfalls in strategies for contrast injection in relation to the ECMO flow, cardiac function and the placement of ECMO cannulas. Contrast-enhanced CT of patients with ECMO requires prior knowledge of the ECMO cannulas, central venous lines, changes of hemodynamics induced by low cardiac output and the influence of adjustment of ECMO on blood flow in order to optimize injection of the contrast material and timing of the scan. Special considerations include temporary reduction of the ECMO flow, selection of the injection site and increasing volume or flow rate of the contrast material.

  17. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV

    PubMed Central

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-01-01

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models. PMID:27892505

  18. Patient-specific structural effects on hemodynamics in the ischemic lower limb artery

    PubMed Central

    Xu, Pengcheng; Liu, Xin; Song, Qi; Chen, Guishan; Wang, Defeng; Zhang, Heye; Yan, Li; liu, Dan; Huang, Wenhua

    2016-01-01

    Lower limb peripheral artery disease is a prevalent chronic non-communicable disease without obvious symptoms. However, the effect of ischemic lower limb peripheral arteries on hemodynamics remains unclear. In this study, we investigated the variation of the hemodynamics caused by patient-specific structural artery characteristics. Computational fluid dynamic simulations were performed on seven lower limb (including superficial femoral, deep femoral and popliteal) artery models that were reconstructed from magnetic resonance imaging. We found that increased wall shear stress (WSS) was mainly caused by the increasing severity of stenosis, bending, and branching. Our results showed that the increase in the WSS value at a stenosis at the bifurcation was 2.7 Pa. In contrast, the isolated stenosis and branch caused a WSS increase of 0.7 Pa and 0.5 Pa, respectively. The WSS in the narrow popliteal artery was more sensitive to a reduction in radius. Our results also demonstrate that the distribution of the velocity and pressure gradient are highly structurally related. At last, Ultrasound Doppler velocimeter measured result was presented as a validation. In conclusion, the distribution of hemodynamics may serve as a supplement for clinical decision-making to prevent the occurrence of a morbid or mortal ischemic event. PMID:27976693

  19. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV.

    PubMed

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-11-28

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models.

  20. Restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension

    PubMed Central

    Garbuzenko, Dmitry Victorovich; Arefyev, Nikolay Olegovich; Belov, Dmitry Vladimirovich

    2016-01-01

    In recent years, defined progress has been made in understanding the mechanisms of hemodynamic disturbances occurring in liver cirrhosis, which are based on portal hypertension. In addition to pathophysiological disorders related to endothelial dysfunction, it was revealed: There is the restructuring of the vasculature, which includes vascular remodeling and angiogenesis. In spite of the fact that these changes are the compensatory-adaptive response to the deteriorating conditions of blood circulation, taken together, they contribute to the development and progression of portal hypertension causing severe complications such as bleeding from esophageal varices. Disruption of systemic and organ hemodynamics and the formation of portosystemic collaterals in portal hypertension commence with neovascularization and splanchnic vasodilation due to the hypoxia of the small intestine mucosa. In this regard, the goal of comprehensive treatment may be to influence on the chemokines, proinflammatory cytokines, and angiogenic factors (vascular endothelial growth factor, placental growth factor, platelet-derived growth factor and others) that lead to the development of these disorders. This review is to describe the mechanisms of restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension. Development of pathogenetic methods, which allow correcting portal hypertension, will improve the efficiency of conservative therapy aimed at prevention and treatment of its inherent complications. PMID:28083082

  1. In vivo measurement of hemodynamic information in stenosed rat blood vessels using X-ray PIV

    NASA Astrophysics Data System (ADS)

    Park, Hanwook; Park, Jun Hong; Lee, Sang Joon

    2016-11-01

    Measurements of the hemodynamic information of blood flows, especially wall shear stress (WSS), in animal models with circulatory vascular diseases (CVDs) are important to understand the pathological mechanism of CVDs. In this study, X-ray particle image velocimetry (PIV) with high spatial resolution was applied to obtain velocity field information in stenosed blood vessels with high WSS. 3D clips fabricated with a 3D printer were applied to the abdominal aorta of a rat cadaver to induce artificial stenosis in the real blood vessel of an animal model. The velocity and WSS information of blood flows in the stenosed vessel were obtained and compared at various stenosis severities. In vivo measurement was also conducted by fastening a stenotic clip on a live rat model through surgical intervention to reduce the flow rate to match the limited temporal resolution of the present X-ray PIV system. Further improvement of the temporal resolution of the system might be able to provide in vivo measurements of hemodynamic information from animal disease models under physiological conditions. The present results would be helpful for understanding the relation between hemodynamic characteristics and the pathological mechanism in animal CVD models.

  2. Patient-specific structural effects on hemodynamics in the ischemic lower limb artery

    NASA Astrophysics Data System (ADS)

    Xu, Pengcheng; Liu, Xin; Song, Qi; Chen, Guishan; Wang, Defeng; Zhang, Heye; Yan, Li; Liu, Dan; Huang, Wenhua

    2016-12-01

    Lower limb peripheral artery disease is a prevalent chronic non-communicable disease without obvious symptoms. However, the effect of ischemic lower limb peripheral arteries on hemodynamics remains unclear. In this study, we investigated the variation of the hemodynamics caused by patient-specific structural artery characteristics. Computational fluid dynamic simulations were performed on seven lower limb (including superficial femoral, deep femoral and popliteal) artery models that were reconstructed from magnetic resonance imaging. We found that increased wall shear stress (WSS) was mainly caused by the increasing severity of stenosis, bending, and branching. Our results showed that the increase in the WSS value at a stenosis at the bifurcation was 2.7 Pa. In contrast, the isolated stenosis and branch caused a WSS increase of 0.7 Pa and 0.5 Pa, respectively. The WSS in the narrow popliteal artery was more sensitive to a reduction in radius. Our results also demonstrate that the distribution of the velocity and pressure gradient are highly structurally related. At last, Ultrasound Doppler velocimeter measured result was presented as a validation. In conclusion, the distribution of hemodynamics may serve as a supplement for clinical decision-making to prevent the occurrence of a morbid or mortal ischemic event.

  3. Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review.

    PubMed

    Ghista, Dhanjoo N; Kabinejadian, Foad

    2013-12-13

    In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs.

  4. Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review

    PubMed Central

    2013-01-01

    In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs. PMID:24330653

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Concurrent bias correction in hemodynamic data assimilation.

    PubMed

    Hu, Zhenghui; Liu, Huafeng; Shi, Pengcheng

    2012-10-01

    Low-frequency drift in fMRI datasets can be caused by various sources and are generally not of interest in a conventional task-based fMRI experiment. This feature complicates the assimilation approach that is always under specific assumption on statistics of system uncertainties. In this paper, we present a novel approach to the assimilation of nonlinear hemodynamic system with stochastic biased noise. By treating the drift variation as a random-walk process, the assimilation problem was translated into the identification of a nonlinear system in the presence of time-varying bias. We developed a bias aware unscented Kalman estimator to efficiently handle this problem. In this framework, the estimates of bias-free states and drift are separately carried out in two parallel filters, the optimal estimates of the system states then are corrected from bias-free states with drift estimates. The approach can simultaneously deal with the fMRI responses and drift in an assimilation cycle in an on-line fashion. It makes no assumptions of the structure and statistics of the drift, thereby is particularly suited for fMRI imaging where the formulation of real drift remains difficult to acquire. Experiments with synthetic data and real fMRI data are performed to demonstrate feasibility of our approach and to explore its potential advantages over classic polynomial approach. Moreover, we include the comparison of the variability of observables from the scanner and of normalized signal used in assimilation procedure in Appendix.

  10. Repeated restraint stress produces acute and chronic changes in hemodynamic parameters in rats.

    PubMed

    Sikora, Mariusz; Konopelski, Piotr; Pham, Kinga; Wyczalkowska-Tomasik, Aleksandra; Ufnal, Marcin

    2016-11-01

    Noninvasive hemodynamic measurements in rats require placing animals in restrainers. To minimize restraint stress-induced artifacts several habituation protocols have been proposed, however, the results are inconclusive. Here, we evaluated if a four-week habituation is superior to a shorter habituation, or no habituation. This is the first study comparing different habituation protocols with the use of four-week continuous telemetry measurements. We did the experiments on male, 16-week old, Sprague-Dawley rats. Continuous recordings of mean arterial blood pressure (MABP) and heart rate (HR) were made before and during habituation protocols. Rats were subjected either to control (four weeks of restraint-free recordings, n = 5) or two-week (seven restraints, n = 6) or four-week (14 restraints, n = 6) restraint sessions. The restraint protocols included placement of rats in the middle of the dark phase into plastic restrainers as used for tail-cuff measurements. Restraint lasted for 60 min, and was repeated every second day. Each restraint significantly increased MABP (by 15-25 mmHg) and HR (by 40-120 beats/min). Exposure to the restraint protocols decreased diurnal variation in MABP. There was no hemodynamic adaptation to repeated restraint, and no significant difference in hemodynamic response to restraint among controls, the two-week and the four-week groups. In conclusion, our study indicates that measurements in restrained rats are not likely being made without stress-induced changes in MABP. Moreover, in hemodynamic studies in repeatedly restrained rats longer habituation is not superior to shorter habituation.

  11. ED 02-3 CLINICAL IMPLICATIONS OF CENTRAL HEMODYNAMICS ON AORTIC AND END-ORGAN DISEASES.

    PubMed

    Hashimoto, Junichiro

    2016-09-01

    The central aorta constitutes the main trunk of the systemic arterial tree. It dilates passively with cardiac ejection during systole and then constricts with its recoil function during diastole, thereby regulating blood pressure and blood flow. The central pulsatile hemodynamics affects local hemodynamics within as well as downstream of the aorta (e.g., end organs).The aorta progressively stiffens and dilates with advancing age, and such age-dependent change is accelerated by hypertension. According to the law of Laplace, wall stress depends on the diameter and pressure of the blood vessel. This has been confirmed by substantial studies which have associated baseline aortic diameter with subsequent development of aortic dissection and progressive dilatation of aortic lumen. This law can also imply potential importance of local pressure within the aorta (i.e., the central pressure) in predicting the development and progression of aortic aneurysms.Several previous studies have shown that hypertension (together with age and obesity) is related to dilatation of the proximal ascending aorta (rather than of the aortic root). In addition, aortic blood flow abnormality may also be importantly related to aortic dilatation because of strong positive association between the diastole flow reversal and lumen diameter in the proximal thoracic aorta. As for the abdominal (infrarenal) aorta, aneurysmal development and progression have been attributed to aortic segmental stiffening (of the bifurcational versus infrarenal segment) and aortic pressure elevation, respectively.Central pulsatile pressure not only represents aortic wall stress but also determines cardiac afterload and microvascular wall stress in the brain and kidney. Central pulsatile flow (in both directions) could also affect the flow distribution into the upper and lower parts of the body and control end-organ function. Aortic structural change (including segmental stiffening and aneurysmal formation) causes central

  12. 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.

  13. Hemodynamic forces regulate developmental patterning of atrial conduction.

    PubMed

    Bressan, Michael C; Louie, Jonathan D; Mikawa, Takashi

    2014-01-01

    Anomalous action potential conduction through the atrial chambers of the heart can lead to severe cardiac arrhythmia. To date, however, little is known regarding the mechanisms that pattern proper atrial conduction during development. Here we demonstrate that atrial muscle functionally diversifies into at least two heterogeneous subtypes, thin-walled myocardium and rapidly conducting muscle bundles, during a developmental window just following cardiac looping. During this process, atrial muscle bundles become enriched for the fast conduction markers Cx40 and Nav1.5, similar to the precursors of the fast conduction Purkinje fiber network located within the trabeculae of the ventricles. In contrast to the ventricular trabeculae, however, atrial muscle bundles display an increased proliferation rate when compared to the surrounding myocardium. Interestingly, mechanical loading of the embryonic atrial muscle resulted in an induction of Cx40, Nav1.5 and the cell cycle marker Cyclin D1, while decreasing atrial pressure via in vivo ligation of the vitelline blood vessels results in decreased atrial conduction velocity. Taken together, these data establish a novel model for atrial conduction patterning, whereby hemodynamic stretch coordinately induces proliferation and fast conduction marker expression, which in turn promotes the formation of large diameter muscle bundles to serve as preferential routes of conduction.

  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. 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

  16. 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.

  17. Portal hypertension: angiographic and hemodynamic evaluation.

    PubMed

    Koolpe, H A; Koolpe, L

    1986-09-01

    There has been a correlation of three hemodynamic parameters with the etiology of portal hypertension and one of the major determinants of therapeutic success, namely, the direction of portal flow. The presence of a 4 mm Hg or greater gradient between the right atrium and the intrahepatic inferior vena cava associated with a "lumpy" pull-back tracing between the wedged and free positions has been associated with alcoholic liver disease. Such patients have antegrade portal flow when their AoD/HWP ratio is in the range of 2.6 to 2.0, and flow becomes stagnant or reversed below this range. Nonalcoholic liver disease is characterized by the absence of a gradient between the right atrium and the inferior vena cava and by a pull-back tracing that falls smoothly and rapidly to the free hepatic vein value. These patients have antegrade portal flow with an AoD/HWP ratio in the range of 1.7 to 1.5. The correct characterization of the cause for diffuse liver disease and direction of portal flow applies to the selection process for patients being considered for the selective distal splenorenal shunt as well as for the newer procedure of orthotopic liver transplantation. It is hoped that the wider application of these physiologic parameters, in the context of an increasing array of imaging tools for the portal system, including high-resolution ultrasound, computed tomography, and magnetic resonance imaging (MRI), will continue to offer all clinicians interested in the problem of portal hypertension a reliable guide to prognosis and the success of the particular treatment provided.

  18. Full Mimicking of Coronary Hemodynamics for Ex-Vivo Stimulation of Human Saphenous Veins.

    PubMed

    Piola, Marco; Ruiter, Matthijs; Vismara, Riccardo; Mastrullo, Valeria; Agrifoglio, Marco; Zanobini, Marco; Pesce, Maurizio; Soncini, Monica; Fiore, Gianfranco Beniamino

    2017-04-01

    After coronary artery bypass grafting, structural modifications of the saphenous vein wall lead to lumen narrowing in response to the altered hemodynamic conditions. Here we present the design of a novel ex vivo culture system conceived for mimicking central coronary artery hemodynamics, and we report the results of biomechanical stimulation experiments using human saphenous vein samples. The novel pulsatile system used an aortic-like pressure for forcing a time-dependent coronary-like resistance to obtain the corresponding coronary-like flow rate. The obtained pulsatile pressures and flow rates (diastolic/systolic: 80/120 mmHg and 200/100 mL/min, respectively) showed a reliable mimicking of the complex coronary hemodynamic environment. Saphenous vein segments from patients undergoing coronary artery bypass grafting (n = 12) were subjected to stimulation in our bioreactor with coronary pulsatile pressure/flow patterns or with venous-like perfusion. After 7-day stimulation, SVs were fixed and stained for morphometric evaluation and immunofluorescence. Results were compared with untreated segments of the same veins. Morphometric and immunofluorescence analysis revealed that 7 days of pulsatile stimulation: (i) did not affect integrity of the vessel wall and lumen perimeter, (ii) significantly decreased both intima and media thickness, (iii) led to partial endothelial denudation, and (iv) induced apoptosis in the vessel wall. These data are consistent with the early vessel remodeling events involved in venous bypass adaptation to arterial flow/pressure patterns. The pulsatile system proved to be a suitable device to identify ex vivo mechanical cues leading to graft adaptation.

  19. Hemodynamic Conditions in a Failing Peripheral Artery Bypass Graft

    PubMed Central

    McGah, Patrick M.; Leotta, Daniel F.; Beach, Kirk W.; Zierler, R. Eugene; Riley, James J.; Aliseda, Alberto

    2012-01-01

    Objective The mechanisms of restenosis in autogenous vein bypass grafts placed for peripheral artery disease are not completely understood. We seek to investigate the role of hemodynamic stress in a case study of a revised bypass graft that failed due to restenosis. Methods The morphology of the lumen is reconstructed from a custom 3D ultrasound system. Scans were taken at one, six, and sixteen months after a patch angioplasty procedure. Computational hemodynamic simulations of the patient-specific model provide the blood flow features and the hemodynamic stresses on the vessel wall at the three time points studied. Results The vessel was initially free of any detectable lesions, but a 60% diameter reducing stenosis developed over the 16 month interval of study. As determined from the simulations, chaotic and recirculating flow occurred downstream of the stenosis due to the sudden widening of the lumen at the patch location. Curvature and a sudden increase in the lumen cross-sectional area induce these flow features that are hypothesized to be conducive to intimal hyperplasia. Favorable agreement was found between simulation results and in vivo Doppler ultrasound velocity measurements. Conclusions Transitional and chaotic flow occurs at the site of the revision, inducing a complex pattern of wall shear are computed with the hemodynamic simulations. This supports the hypothesis that the hemodynamic stresses in the revised segment, produced by the coupling of vessel geometry and chaotic flow, led to the intimal hyperplasia and restenosis of the graft. PMID:22551907

  20. Vasopressin Improves Hemodynamic Status in Infants with Congenital Diaphragmatic Hernia

    PubMed Central

    Acker, Shannon N.; Kinsella, John P.; Abman, Steven H.; Gien, Jason

    2014-01-01

    Objective To assess the ability of vasopressin to stabilize hemodynamics in infants with systemic hypotension secondary to congenital diaphragmatic hernia (CDH). Study design A retrospective chart review was performed to identify 13 patients with CDH treated with vasopressin for refractory hypotension, to assess the effect of vasopressin on pulmonary and systemic hemodynamics and gas exchange in this setting. Data collected included demographics, respiratory support, inotropic agents, pulmonary and systemic hemodynamics, urine output, and serum and urine sodium levels during vasopressin therapy. Results Vasopressin therapy increased mean arterial pressure and decreased pulmonary: systemic pressure ratio, heart rate and FiO2. In 6 of 13 patients, ECMO was no longer indicated after vasopressin treatment. Improvement in left ventricular (LV) function and oxygenation index after vasopressin initiation were associated with a decreased need for ECMO. Prolonged vasopressin treatment was associated with hyponatremia, increased urine output and increased urine sodium. Conclusions Vasopressin stabilized systemic hemodynamics without adverse effects on pulmonary hemodynamics in a subset of infants with CDH. Our results suggest a potential role for vasopressin therapy in patients with CDH with catecholamine resistant refractory hypotension. PMID:24840762

  1. Use of Bioimpedance to Assess Changes in Hemodynamics During Acute Administration of CPAP

    PubMed Central

    Digby, Genevieve C.; Driver, Helen S.; Fitzpatrick, Michael; Ropchan, Glorianne; Parker, Christopher M.

    2011-01-01

    Background Attempts to investigate the mechanisms by which continuous positive airway pressure (CPAP) therapy improves heart function in patients with obstructive sleep apnea (OSA) have been limited by the lack of non-invasive methods to assess cardiac performance. We used transthoracic electrical bioimpedance (TEB) to assess acute hemodynamic changes including heart rate (HR), stroke volume (SV), cardiac output (CO) and cardiac index (CI) during PAP titration in (1) post-operative cardiac surgery patients, (2) patients with severe OSA, and (3) normal healthy volunteers. Methods Post-operative cardiac surgery patients were studied via TEB and pulmonary artery catheter (PAC) during acute titration of positive end-expiratory pressure (PEEP) while mechanically ventilated. Patients with severe OSA were studied non-invasively by TEB during acute CPAP titration in supine stage 2 sleep, and normal subjects while awake and recumbent. Results In post-operative cardiac surgery patients (n = 3), increasing PEEP to 18 cmH2O significantly reduced SV and CI relative to baseline. There was no difference between TEB and PAC in terms of ability to assess variations in hemodynamic parameters. In patients with severe OSA (n = 3), CPAP titration to optimal pressure to alleviate obstructive apneas reduced HR, SV, CO and CI significantly compared to without CPAP. In three healthy subjects, maximal tolerated CPAP reduced SV and CO significantly compared to baseline. Conclusions Acute administration of CPAP causes a decrease in CO and CI, apparently a consequence of a reduction in SV. TEB appears to be an accurate and reproducible non-invasive method of detecting changes in hemodynamics.

  2. The effect of indomethacin on systemic and renal hemodynamics in neonatal piglets during experimental endotoxemia.

    PubMed

    Furtado, Nicholas; Beier, Ulf H; Gorla, Sema Rao; Fornell, Linda; Lumpaopong, Adisorn; Radhakrishnan, Jayant; John, Eunice

    2008-08-01

    Systemic and renal hemodynamics are affected by prostaglandin production during endotoxemia. To study indomethacin effects on endotoxinemia in a neonatal piglet model, sixteen 7-10 day old piglets were anesthetized, ventilated, and catheterized. Mean arterial pressure (MAP), heart rate (HR), and urine output were continuously monitored. Endotoxin (0.06 mcg/kg) was injected after baseline measurements. We studied two groups with either endotoxinemia alone (n = 7) or an additional indomethacin infusion (0.2 mg/kg per h, n = 9). HR, MAP, renal blood flow (RBF), systemic and renal vascular resistance (SVR, RVR), cardiac index (CI), and glomerular filtration rate (GFR), were obtained at baseline, at 1, 2 and 3 h. We observed a drop in CI and an increase in SVR and HR within 3 h of endotoxinemia, while MAP remained unchanged. These effects were prevented by indomethacin. RVR was not altered significantly. Endotoxinemia triggered a drop of RBF in both control (P < 0.01) and intervention group (P < 0.05). In the intervention group, drop of GFR, urine volume, and paraaminohippuric acid clearance were apparent signs of nephrotoxicity (P < 0.01, <0.05, and <0.01). In conclusion, indomethacin maintains hemodynamic parameters during endotoxinemia at the expense of nephrotoxicity. We speculate that indomethacin counteracts the renoprotective effect of prostaglandins.

  3. Effect of inhibition of converting enzyme on renal hemodynamics and sodium management in polycystic kidney disease.

    PubMed

    Torres, V E; Wilson, D M; Burnett, J C; Johnson, C M; Offord, K P

    1991-10-01

    We compared the tubular transport of sodium and the erythrocyte sodium-lithium countertransport activity in hypertensive patients with autosomal dominant polycystic kidney disease (ADPKD) and in normotensive control subjects. In addition, we assessed the effects of inhibition of converting enzyme on renal hemodynamics and sodium excretion in hypertensive patients with ADPKD to provide information on mechanisms responsible for the increased renal vascular resistance and filtration fraction and the adjustment of the pressure-natriuresis relationship during saline expansion, observed in patients with ADPKD, hypertension, and preserved renal function. In comparison with normotensive control subjects, the hypertensive patients with ADPKD had lower renal plasma flows, higher renal vascular resistances and filtration fractions, and similar proximal and distal fractional reabsorptions of sodium. The administration of enalapril resulted in significant increases in the renal plasma flow and significant reductions in mean arterial pressure, renal vascular resistance, and filtration fraction, but the glomerular filtration rate remained unchanged. Despite the significant reduction in mean arterial pressure during inhibition of converting enzyme, the distal fractional reabsorption of sodium decreased while the total fractional excretion of sodium remained unchanged or increased slightly. No significant differences were detected between the normotensive control subjects and the hypertensive patients with ADPKD in erythrocyte sodium-lithium countertransport activity, plasma renin activity, plasma aldosterone concentration, or atrial natriuretic factor. These results suggest that the renal renin-angiotensin system plays a central role in the alterations in renal hemodynamics and sodium management associated with the development of hypertension in ADPKD.

  4. [The hemodynamic effect of thoracic sympathetic ganglion blockade in the anesthetized adult mongrel dogs].

    PubMed

    Yamagami, H

    1994-03-01

    Hemodynamic alterations with the thoracic sympathetic ganglion blockade were elucidated in the anesthetized open-chest dogs, under controlled ventilation with 100% oxygen and receiving fentanyl, pentobarbital and pancuronium administration, and the effect of blockade was assessed by increase in skin-surface temperature at the specific regions of the upper extremity. All dogs with thoracic sympathetic ganglion blockade revealed the increased skin temperature in blocked extremities and decreased skin temperature in the contralateral side with simultaneous compensatory vasoconstriction ("Borrowing-Lending phenomenon"). Four groups were classified according to the side and range of blockade: A-group (right Th7.8 ganglion, N = 17), B-group (left-Th7.8 ganglion, N = 8), C-group (right Th2.3 ganglion, N = 13) and D-group (left-Th2.3 ganglion, N = 10). The hemodynamic variables after the middle thoracic sympathetic ganglion blockade showed no remarkable changes but heart-rate, mean arterial blood pressure and cardiac output decreased significantly with the upper right-side thoracic sympathetic ganglion blockade, and the inhibited circulatory state lasted twenty minutes after blockade. No significant skin temperature changes were observed after blockade among four groups. The results suggest that the patient after upper thoracic sympathetic ganglion blockade should be cared with these circulatory changes in mind.

  5. Fertility and uterine hemodynamic in cows after artificial insemination with semen assessed by fluorescent probes.

    PubMed

    Oliveira, Bruna Marcele; Arruda, Rubens Paes; Thomé, Helder Esteves; Maturana Filho, Milton; Oliveira, Guilherme; Guimarães, Carina; Nichi, Marcílio; Silva, Luciano Andrade; Celeghini, Eneiva Carla Carvalho

    2014-09-15

    Fluorescent probes (propidium iodide, Hoechst 33342, fluorescein isothiocyanate-conjugated Pisum sativum agglutinin, and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide) were used to simultaneously evaluate the integrity of plasma and acrosomal membranes as well as mitochondrial membrane function in cryopreserved bovine semen and to verify its influence on fertility and postinsemination uterine vascularization. One hundred eighty-two Nellore cows were distributed for artificial insemination (AI) using semen batches separated according to the cell percentage presenting intact plasma membrane, intact acrosome, and high mitochondrial function (IPIAH): group G (44.5% IPIAH, n = 68), group M (23.0% IPIAH, n = 56), and group R (8.5% IPIAH, n = 58). The uterine hemodynamic was evaluated by Doppler sonogram in three periods: 30 hours before AI, 4 and 24 hours after AI were considered the resistance index and the uterine vascularization score. The pregnancy rate of group G (64.7%) was greater (P > 0.05) compared with group R (36.2%), but both did not differ from group M (50.0%). There was no effect (P > 0.05) of semen quality on uterine vascularization. Greater vascularization was noticed 4 hours after AI than 30 hours before and 24 hours after AI. Semen evaluation using fluorescent probes contributes to predicting fertilizing potential of semen. The use of semen with less percentage of IPIAH sperm does not alter uterine hemodynamic in cows.

  6. Effects of a left ventricular assist device with a centrifugal pump on left ventricular diastolic hemodynamics.

    PubMed

    Saito, Akira

    2002-10-01

    The purpose of this investigation was to analyze how left ventricular assist device (LVAD) with a centrifugal pump alters left ventricular diastolic hemodynamics and energy by means of a left ventricular pressure volume relationship. Fifteen anesthetized normal pig hearts were studied after placement of an apical drainage LVAD with a centrifugal pump. Indices of the left ventricular isovolumic relaxation phase, left ventricular filling phase and general hemodynamic data were recorded with the LVAD in on and off situations. The pump assist rate was adjusted to 25%, 50% and 75%. Left ventricular stroke work, with a high correlation with oxygen consumption, decreased as the assist rate increased. Left ventricular relaxation delayed as the assist rate increased, but the atrioventricular pressure gradient increased in the left ventricular rapid filling phase. This finding clarifies left ventricular rapid filling. In this study, it was suggested that although left ventricular isovolumic relaxation was affected, 75% assistance is the most effective for the pump flow in terms of circulation support and restoration of cardiac function.

  7. The optimal hemodynamics management of post-cardiac arrest shock.

    PubMed

    Pellis, Tommaso; Sanfilippo, Filippo; Ristagno, Giuseppe

    2015-12-01

    Patients resuscitated from cardiac arrest develop a pathophysiological state named "post-cardiac arrest syndrome." Post-resuscitation myocardial dysfunction is a common feature of this syndrome, and many patients eventually die from cardiovascular failure. Cardiogenic shock accounts for most deaths in the first 3 days, when post-resuscitation myocardial dysfunction peaks. Thus, identification and treatment of cardiovascular failure is one of the key therapeutic goals during hospitalization of post-cardiac arrest patients. Patients with hemodynamic instability may require advanced cardiac output monitoring. Inotropes and vasopressors should be considered if hemodynamic goals are not achieved despite optimized preload. If these measures fail to restore adequate organ perfusion, a mechanical circulatory assistance device may be considered. Adequate organ perfusion should be ensured in the absence of definitive data on the optimal target pressure goals. Hemodynamic goals should also take into account targeted temperature management and its effect on the cardiovascular function.

  8. Non-invasive quantification of hemodynamics in human choriocapillaries

    NASA Astrophysics Data System (ADS)

    Yu, Huidan (Whitney); Chen, Rou; An, Senyou; McDonough, James; Gelfand, Bradley; Yao, Jun

    2016-11-01

    The development of retinal disease is inextricably linked to defects in the choroidal blood supply. However, to date a description of the hemodynamics in the human choroidal circulation is lacking. Through high resolution choroidal vascular network mapped from immunofluorescent labeling and confocal microscopy of human cadaver donor eyes. We noninvasively quantify hemodynamics including velocity, pressure, and wall-shear stress (WSS) in choriocapillaries through mesoscale modeling and GPU-accelerated fast computation. This is the first-ever map of hemodynamic parameters (WSS, pressure, and velocity) in anatomically accurate human choroidal vasculature in health and disease. The pore scale simulation results are used to evaluate porous media models with the same porosity and boundary conditions. School of Medicine, Indiana University.

  9. Cerebral Hemodynamics With rTMS in Alcohol Dependence: A Randomized, Sham-Controlled Study.

    PubMed

    Mishra, Biswa Ranjan; Maiti, Rituparna; Nizamie, S Haque

    2016-04-08

    The authors studied cerebral hemodynamics in alcohol dependence and evaluated their changes with application of high-frequency rTMS. A prospective, single-blind, randomized, parallel-group, sham-controlled clinical study was conducted with patients with alcohol dependence (DSM-IV-TR). The study population comprised 25 subjects each in active rTMS, sham rTMS, and healthy control groups. At baseline, cerebral hemodynamic indices were measured with transcranial Doppler sonography. Subjects in the active rTMS group received 10 sessions of rTMS daily; the sham group was administered sham rTMS with the same parameters. Cerebral hemodynamic parameters were repeated 5 minutes after the last rTMS session. At baseline, mean velocity (MV) of both middle cerebral artery (MCA; R-MCA: p=0.003; L-MCA: p=0.002) and anterior cerebral artery (ACA; R-ACA: p=0.003; L-ACA: p=.001) was significantly reduced. Pulsatility index (PI) of MCA (p<0.001) and resistance index (RI) of ACA (R-ACA: p=0.009; L-ACA: p=0.008) were increased in alcohol-dependent subjects in comparison with healthy controls. In the active rTMS group, except L-MCA PI, significant differences were observed in values of MV, PI, and RI of both MCA and ACA following rTMS intervention; such changes were not evident in the sham rTMS group. The changes in mean difference in MV of L-MCA (p=0.006) and L-ACA (p=0.015) were statistically significant in the active rTMS group, in comparison with the sham group. Significant differences were also observed between the two groups postintervention, in RI of L-MCA (p=0.001) and ACA (R-ACA: p=0.010; L-ACA: p=0.015). Alcohol dependence may result in altered cerebral hemodynamic parameters, which can be improved with high-frequency rTMS application.

  10. 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

  11. 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

  12. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow

    NASA Astrophysics Data System (ADS)

    Nitta, N.; Homma, K.

    Hemodynamic forces including blood pressure and shear stress affect vulnerable plaque rupture in arteriosclerosis and biochemical activation of endothelium such as NO production. In this study, a method for estimating and imaging shear stress and pressure gradient distributions in blood vessel as the hemodynamic force based on viscosity estimation is presented. Feasibility of this method was investigated by applying to human carotid blood flow. Estimated results of shear stress and pressure gradient distributions coincide with the ideal distributions obtained by numerical simulation and flow-phantom experiment.

  13. The clinical and hemodynamic presentation of the shock patient.

    PubMed

    Summers, G

    1990-06-01

    It is the nurse's responsibility to assess the critically ill patient and to interpret data so that therapy can be directed to optimally treat that individual. Shock is a complex progressive syndrome that includes specific types, such as cardiogenic, septic, anaphylactic, and hypovolemic. Clinical and hemodynamic parameters provide clues to the specific type of shock and its clinical progress. The progression of the shock state must be monitored by critical care nurses who are knowledgeable of and proficient in clinical assessment skills and the acquisition and interpretation of significant hemodynamic data.

  14. 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.

  15. 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

  16. Circadian rhythms of renal hemodynamics in unanesthetized, unrestrained rats.

    PubMed

    Pons, M; Tranchot, J; L'Azou, B; Cambar, J

    1994-10-01

    Catheters were placed in the jugular vein and femoral artery of male Sprague-Dawley rats and connected to a specially designed perfusor for continuous constant infusion of 0.9% NaCl and a syringe to perform simultaneous and intermittent blood collections. This permitted continuous 24-h study of renal hemodynamics, estimated by inulin (Cin) and p-amino-hippuric acid (CPAH) clearances; Cin represents glomerular filtration rate and CPAH renal plasma flow. Animals were individually housed in metabolism cages in a controlled environment with light/dark 12:12 h. Urine was collected every 4 h (12:00, 16:00, 20:00, 24:00, 04:00, and 08:00) and blood sampled at the midpoint of urine collection periods. Urine and plasma sodium, potassium, inulin, and PAH were spectrophotometrically assessed. During continuous infusion of isotonic saline, Cin exhibited circadian changes with large decrease between 12:00 and 20:00 h (0.9 +/- 0.2 ml/min) and acrophase at 00:30 h. Rhythmicity in CPAH was similar with the minimum between 16:00 and 20:00 h (2.5 +/- 0.3 ml/min) and peak between 00:00 and 04:00 h (acrophase at 00:25 h). Water and electrolyte excretion were also circadian rhythmic with a similar nighttime enhancement and daytime minimum. Such circadian changes persisted during continuous 0.9% NaCl infusion for several consecutive days. The unanesthetized, unrestrained rat model enables investigations in renal chronopharmacology and chronotoxicology.

  17. In vivo imaging of hepatic hemodynamics and light scattering property during ischemia-reperfusion in rats based on spectrocolorimetry

    PubMed Central

    Akter, Sharmin; Kawauchi, Satoko; Sato, Shunichi; Aosasa, Suefumi; Yamamoto, Junji; Nishidate, Izumi

    2017-01-01

    A red-green-blue camera-based imaging method is proposed for estimating spatial maps of concentrations of oxyhemoglobin (CHbO), deoxyhemoglobin (CHbR), total hemoglobin (CHbT), tissue oxygen saturation (StO2), and scattering power (b) in liver tissue. Hemodynamic responses to hepatic ischemia-reperfusion of in vivo rat liver tissues induced by portal triad occlusion were evaluated. Upon portal triad occlusion, this method yielded images of decreased CHbO, CHbT, StO2, and b, and increased CHbR followed by a progressive increase in CHbO and StO2 during reperfusion. Time courses of the changes in CHbO, CHbR, CHbT, and StO2 over different regions of interest (ROIs) revealed that ischemia results in an abrupt significant (P<0.05) reduction in CHbO, CHbT, and StO2 with a simultaneous increase in CHbR compared to the baseline level, indicative of the hemodynamic responses during hepatic ischemia-reperfusion. Upon reperfusion, there was a gradual increase in CHbO and StO2, and decrease in CHbR. The change in average scattering power b implies the presence of morphological alterations in the cellular and subcellular structures induced by ischemia or anoxia. This study shows the potential of monitoring spatiotemporal changes in hemodynamic parameters and morphological changes in studies of hepatic pathophysiology. PMID:28270997

  18. Atherosclerosis-prone hemodynamics differentially regulates endothelial and smooth muscle cell phenotypes and promotes pro-inflammatory priming.

    PubMed

    Hastings, Nicole E; Simmers, Michael B; McDonald, Oliver G; Wamhoff, Brian R; Blackman, Brett R

    2007-12-01

    Atherosclerosis is an inflammatory disease that preferentially forms at hemodynamically compromised regions of altered shear stress patterns. Endothelial cells (EC) and smooth muscle cells (SMC) undergo phenotypic modulation during atherosclerosis. An in vitro coculture model was developed to determine the role of hemodynamic regulation of EC and SMC phenotypes in coculture. Human ECs and SMCs were plated on a synthetic elastic lamina and human-derived atheroprone, and atheroprotective shear stresses were imposed on ECs. Atheroprone flow decreased genes associated with differentiated ECs (endothelial nitric oxide synthase, Tie2, and Kruppel-like factor 2) and SMCs (smooth muscle alpha-actin and myocardin) and induced a proinflammatory phenotype in ECs and SMCs (VCAM-1, IL-8, and monocyte chemoattractant protein-1). Atheroprone flow-induced changes in SMC differentiation markers were regulated at the chromatin level, as indicated by decreased serum response factor (SRF) binding to the smooth muscle alpha-actin-CC(a/T)(6)GG (CArG) promoter region and decreased histone H(4) acetylation. Conversely, SRF and histone H(4) acetylation were enriched at the c-fos promoter in SMCs. In the presence of atheroprotective shear stresses, ECs aligned with the direction of flow and SMCs aligned more perpendicular to flow, similar to in vivo vessel organization. These results provide a novel mechanism whereby modulation of the EC phenotype by hemodynamic shear stresses, atheroprone or atheroprotective, play a critical role in mechanical-transcriptional coupling and regulation of the SMC phenotype.

  19. 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

  20. [Influence of iron nanoparticles on cardiac performance and hemodynamics in rabbits after intravenous administration in acute experiment].

    PubMed

    Doroshenko, A M

    2014-01-01

    Iron nanoparticles are possessed by high potential in the creation of effective and safe antianemic drugs due to the enhanced biological activity of metal nanoparticles. As a step of intravenous dosage form development the study of short-term effects of iron nanoparticles on the cardiovascular system is important. Dose-dependent changes of systemic hemodynamics' parameters were established in acute experiment on rabbits after several intravenous injections of zero-valent iron nanoparticles solution.

  1. 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

  2. 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.

  3. The acute effect of resistance exercise with blood flow restriction with hemodynamic variables on hypertensive subjects.

    PubMed

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

    2014-09-29

    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.

  4. Thirst Perception and Osmoregulation of Vasopressin Secretion Are Altered During Recovery From Septic Shock

    PubMed Central

    Siami, Shidasp; Polito, Andrea; Porcher, Raphael; Hissem, Tarik; Blanchard, Anne; Boucly, Catherine; Carlier, Robert; Annane, Djillali; Haymann, Jean-Philippe; Sharshar, Tarek

    2013-01-01

    Objective Vasopressin (AVP) secretion during an osmotic challenge is frequently altered in the immediate post-acute phase of septic shock. We sought to determine if this response is still altered in patients recovering from septic shock. Design Prospective interventional study Setting Intensive care unit (ICU) at Raymond Poincaré and Etampes Hospitals. Patients Normonatremic patients at least 5 days post discontinuation of catecholamines given for a septic shock. Intervention Osmotic challenge involved infusing 500 mL of hypertonic saline solution (with cumulative amount of sodium not exceeding 24 g) over 120 minutes. Measurements and main results Plasma AVP levels were measured 15 minutes before the infusion and then every 30 minutes for two hours. Non-responders were defined as those with a slope of the relation between AVP and plasma sodium levels less than < 0.5 ng/mEq. Among the 30 included patients, 18 (60%) were non-responders. Blood pressure and plasma sodium and brain natriuretic peptide levels were similar in both responders and non-responders during the course of the test. Critical illness severity, hemodynamic alteration, electrolyte disturbances, treatment and outcome did not differ between the two groups. Responders had more severe gas exchange abnormality. Thirst perception was significantly diminished in non-responders. The osmotic challenge was repeated in 4 non-responders several months after discharge and the abnormal response persisted. Conclusion More than half of patients recovering from septic shock have an alteration of osmoregulation characterised by a dramatic decrease in vasopressin secretion and thirst perception during osmotic challenge. The mechanisms of this alteration but also of the relationship between haematosis and normal response remain to be elucidated. PMID:24223220

  5. 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.

  6. Quantifying the Large-Scale Hemodynamics of Intracranial Aneurysms

    PubMed Central

    Byrne, G.; Mut, F.; Cebral, J.

    2013-01-01

    BACKGROUND AND PURPOSE Hemodynamics play an important role in the mechanisms that govern the initiation, growth, and possible rupture of intracranial aneurysms. The purpose of this study was to objectively characterize these dynamics, classify them, and connect them to aneurysm rupture. MATERIALS AND METHODS Image-based computational fluid dynamic simulations were used to re-create the hemodynamics of 210 patient-specific intracranial aneurysm geometries. The hemodynamics were then classified according to their spatial complexity and temporal stability by using quantities derived from vortex core lines and proper orthogonal decomposition. RESULTS The quantitative classification was compared with a previous qualitative classification performed by visual inspection. Receiver operating characteristic curves provided area-under-the-curve estimates for spatial complexity (0.905) and temporal stability (0.85) to show that the 2 classifications were in agreement. Statistically significant differences were observed in the quantities describing the hemodynamics of ruptured and unruptured intracranial aneurysms. Specifically, ruptured aneurysms had more complex and more unstable flow patterns than unruptured aneurysms. Spatial complexity was more strongly associated with rupture than temporal stability. CONCLUSIONS Complex-unstable blood flow dynamics characterized by longer core line length and higher entropy could induce biologic processes that predispose an aneurysm for rupture. PMID:23928142

  7. 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)

  8. [Ibopamine--acute hemodynamic, renal and neurohumoral effects].

    PubMed

    Wehling, M; Theisen, K

    1991-01-01

    Ibopamine (IP) is a novel dopamine analogue for which beneficial effects have been shown in chronic heart failure. Hemodynamic effects of the substance include an increase in cardiac output and a decrease in the peripheral resistance. Aside from these hemodynamic effects, changes in renal (increased diuresis) and neurohumoral parameters (decreased plasma renin activity, aldosterone, norepinephrine, increased ANF and cGMP) have been found. The renal effects may originate from three independent mechanisms: 1) direct impact of improved hemodynamic parameters on the renal perfusion; 2) the improved cardiac performance results in a reduction of compensatory hormonal adaptations, such as the activation of the renin-angiotensin-aldosterone-axis or the sympathetic system; 3) direct effects on the intrarenal hemodynamic and glomerular/tubular functions induced by stimulation of renal dopaminergic receptors. The continued decrease of the plasma renin activity by 35% results in a reduction of the plasma levels of angiotensin II and aldosterone. Additionally, an increase in plasma atrial natriuretic factor (ANF) and its second messenger cyclic guanosine monophosphate (cGMP) was observed after ibopamine, which could contribute to the diuretic action of the drug. These findings underline the importance of extrarenal effects of a drug in the treatment of heart failure, this may essentially contribute to the improvement of cardiac performance, independent of positive inotropy.

  9. 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).

  10. Restrictive hemodynamics are present at the time of diagnosis of allograft coronary artery disease in children.

    PubMed

    Law, Yuk; Boyle, Gerard; Miller, Susan; Clendaniel, James; Ettedgui, Jose; Beerman, Lee; Counihan, Peter; Webber, Steven

    2006-12-01

    Clinical recognition of allograft coronary artery disease (ACAD) is challenging. We examined whether right heart hemodynamics can aid its diagnosis in pediatric recipients. We retrospective analyzed hemodynamic data of recipients with ACAD versus age and date-of-transplant matched controls. From 1982-2001, 18 cases fulfilled study entry criteria. Median age at transplant was 12 years for subjects and 8 years for controls. Median time to diagnosis of ACAD was 65 months (14.5-124 months) and 67 months (16-140 months) to arteriography for controls. The median right ventricular end-diastolic pressure (RVEDP) at diagnosis was 11.0 vs. 6.0 mmHg for controls (p = 0.003). Pulmonary capillary wedge pressure (PCWP) at diagnosis was 14.0 vs. 8.0 mmHg for controls (p = 0.001). When subdivided by severity of ACAD, the difference was greater in the moderate/severe group. Compared to the previous catheterization (median interval 10 months for subjects, 12.0 for controls ), there was an increase of 4.0 mmHg in RVEDP in ACAD subjects (n = 13, p = .003) versus 0 mmHg in controls (p = 0.042), and an increase in PCWP of 5.5 in subjects (p = .002) versus 0 mmHg in controls (p = 0.066). The presence of elevated filling pressures plus an interim increase should alert to the presence of ACAD and help guide further investigation.

  11. The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

    PubMed Central

    Sundareswaran, Kartik S.; Pekkan, Kerem; Dasi, Lakshmi P.; Whitehead, Kevin; Sharma, Shiva; Kanter, Kirk R.; Fogel, Mark A.; Yoganathan, Ajit P.

    2008-01-01

    Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96 ± 0.80 WU) and systemic vascular resistances (18.4 ± 7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39 ± 0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n = 16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output (CO) dependence on TCPC resistance was negligible (sensitivity = −0.064 l·min−1·WU−1) but not for the SV circulation (sensitivity = −0.88 l·min−1·WU−1). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+35%) and decreased preload (−12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology. PMID:18931028

  12. Impact of the calf perforators on the venous hemodynamics in primary varicose veins.

    PubMed

    Recek, C

    2006-12-01

    The hemodynamic significance of the calf perforating veins continues to be the point of controversy. The conception that incompetent perforating veins cause hemodynamic disturbance and are responsible for the formation of leg ulceration has still many adherents prefering perforator surgery, whereas others reject any causal relation between large, incompetent perforators and severe forms of chronic venous insufficiency. In this study well documented facts concerning the impact of the calf perforators on the venous hemodynamics are reviewed. There is a bidirectional flow within calf perforators in healthy subjects enabling a quick equilibration of pressure changes produced during calf muscle contractions and relaxations, so that recordings of the mean pressure display identical values in superficial and deep veins of the lower leg, a feature typical of conjoined vessels. In cases with saphenous reflux, the bidirectional flow within calf perforators has a distinct inward vector directed to the deep veins; this inward component is the more pronounced, the larger the saphenous reflux is. Incompetent calf perforators do not cause ambulatory venous hypertension, exactly the opposite happens: the high hydrostatic pressure found in the quiet standing position drops significantly during ambulation, as soon as the saphenous reflux is interrupted. In primary varicose veins calf perforators can not become the source of reflux because they are situated at the lower pole of the ambulatory pressure gradient, which occurs between thigh and lower leg veins during ambulation. The size of the calf perforators is determined by the amount of saphenous reflux. When the saphenous reflux is abolished (e.g. by high ligation), the enlarged calf perforators diminish.

  13. [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.

  14. Bedside calculation of hemodynamic parameters with a hand-held programmable calculator. Part I.: Choice of hemodynamic formulas.

    PubMed

    Laurent, M

    1980-01-01

    Currently used hemodynamic and oxygen transport formulas are reviewed in order to chose the shortest form compatible with an optimal clinical accuracy. Programming of hand held calculators with these selected equations spares steps available in the program memory. (Acta anaesth. belg., 1980, 31, 45-52).

  15. Comprehensive physiological cardiovascular model enables automatic correction of hemodynamics in patients with acute life-threatening heart failure.

    PubMed

    Uemura, Kazunori; Kamiya, Atsunori; Shimizu, Shuji; Shishido, Toshiaki; Sugimachi, Masaru; Sunagawa, Kenji

    2006-01-01

    Saving life of patients with acute life-threatening heart failure is a major challenge. One has to correct several fatal hemodynamic abnormalities at the same time within a limited time frame. The formulation of such complicated treatments enables the development of a system that can be used to save automatically lives of patients with acute heart failure, an autopilot system. To accomplish this, we established a comprehensive physiological cardiovascular model, on which we based the design of the autopilot system. By translating hemodynamics into cardiovascular parameters (pumping ability, vascular resistance, blood volume), and by controlling each of these with individual drugs, we were able to correct blood pressure, cardiac output, and left atrial pressure to the target values rapidly (5.2 +/- 6.6, 6.8 +/- 4.6, and 11.7 +/- 9.8 minutes), stably, and simultaneously.

  16. Endothelial Receptor a Blockade Alters the Hemodynamic Response to Nitric Oxide Inhibition in the Rat

    DTIC Science & Technology

    2007-11-02

    pressure and a fall in renal blood flow and GFR (3,9,19,22). These studies indicate that the constitutive production of NO contibutes to the modulation...of basal vascular tone in the resistance vessels of the kidney and other organs and plays an essential role in the regulation of blood pressure and...probe in the carotid artery and maintained between 36 and 38°C. Both femoral arteries were cannulated with PE-50 tubing, one for blood pressure

  17. Hypertension in primary immunoglobulin A nephropathy (Berger's disease): hemodynamic alterations and mechanisms.

    PubMed

    Valvo, E; Gammaro, L; Bedogna, V; Giorgetti, P G; Tonon, M; Panzetta, G O; Lupo, A; Loschiavo, C; Tessitore, N; Oldrizzi, L

    1987-01-01

    Twenty-two patients with primary IgA nephropathy (Berger's disease), 12 with normal and 10 with high blood pressure, were studied. The mean intra-arterial pressure was 88 +/- 6 mm Hg in the normotensive group and 113 +/- 10mm Hg in hypertensive patients; plasma renin activity was high in normotensives and normal in hypertensives. The glomerular filtration rate was 83 +/- 23 and 73 +/- 26 ml/m in 1.73 m2 in normotensive and hypertensive patients, respectively (p = n.s.). Blood volume was high in IgA nephropathy patients: 82 +/- 12 ml/kg body weight in normotensives and 96 +/- 7 ml/kg body weight in hypertensives. Mean arterial pressure was significantly correlated with blood volume (r = 0.541, p less than 0.01), but not with plasma renin activity and glomerular filtration rate. The cardiac index was high in both groups: 4.20 +/- 0.88 liters/min/m2 in normotensive and 3.95 +/- 0.87 liters/min/m2 in hypertensive patients. The total peripheral resistance index was significantly lower than normal in normotensives (1,659 +/- 387 dyn/s/cm-5/m2) and significantly higher (2,419 +/- 562 dyn/s/cm-5 m2) in hypertensives. The cardiac index did not correlate with blood volume and mean arterial pressure; a positive correlation was found between mean arterial pressure and peripheral vascular resistance (r = 0.630, p less than 0.01). No correlation was observed between blood volume and plasma renin activity. Our study indicates that hypertension in IgA nephropathy is primarily volume dependent, and that this increase in blood volume is not related to the deterioration of renal function. The role of the renin-angiotensin system in the maintenance of the hypertension is not well-defined.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Comparison of the pulsatility index and input impedance parameters in a model of altered hemodynamics.

    PubMed

    Downing, G J; Yarlagadda, A P; Maulik, D

    1991-06-01

    Clinical use of Doppler waveform analysis assumes that vascular resistance is accurately represented by the Doppler indices. This assumption was examined by correlating the pulsatility index (PI) with measures of input impedance including peripheral vascular resistance (Zpr), characteristic impedance (Zo), and reflection coefficient (Rc). Assessment of these parameters from the descending aorta was performed in five chronically instrumented, newborn lambs subjected to administration of norepinephrine and hydralazine. Significant increases in PI, Zpr, Zo, and Rc were seen in response to administration of norepinephrine, and decreases in PI and Zpr occurred with hydralazine use. Significant correlation existed between PI and Zpr throughout the study, but changes in PI did not correlate with changes in Zo and Rc. PI appears to reflect changes in Zpr accurately. However, the lack of ability for PI to assess Zo or Rc requires further investigation.

  19. Exercise pretraining attenuates endotoxin-induced hemodynamic alteration in type I diabetic rats.

    PubMed

    Hung, Ching-Hsia; Chen, Yu-Wen; Shao, Dong-Zi; Chang, Che-Ning; Tsai, Yung-Yuh; Cheng, Juei-Tang

    2008-10-01

    Higher expression of heat shock protein 72 (HSP72) reduces the mortality rate and organ damage in septic shock and prevents cardiac mitochondrial dysfunction due to lipopolysaccharide (LPS). Our hypothesis is that exercise preconditioning may increase the expression of HSP72 in heart and the nucleus tractus solitarii (NTS) of the brain to alleviate the cardiovascular dysfunction in type I diabetic rats receiving endotoxin. Wistar rats were randomly assigned to the following groups: sedentary normal, sedentary type I diabetic rats, and type I diabetic rats with exercise training. The trained rats ran on a treadmill 5 d.week-1, 30-60 min.d-1, at an intensity of 1.0 mile.h-1 (1 mile = 1.6 km) over a 3 week period. Twenty-four hours after the last training session, we compared the temporal profiles of mean arterial pressure, heart rate, cardiac output, stroke volume, and serum tumor necrosis factor alpha level in rats receiving an injection of LPS. In addition, HSP72 expression in heart and NTS from each group was determined. We found that HSP72 expression in the heart and NTS was significantly increased in diabetic rats with exercise training. After administration of LPS, the survival time was significantly longer in diabetic rats with exercise training. Additionaly, serum tumor necrosis factor alpha levels decreased as compared with those rats not receiving exercise training. Exercise training also diminished cardiovascular dysfunction in diabetic rats during endotoxemia. These data suggest that exercise may increase the expression of HSP72 in the heart and NTS to protect against the high mortality rate and attenuate cardiovascular dysfunction in diabetic rats during endotoxemia.

  20. 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

  1. 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.

  2. Postprandial hemodynamics in the conscious rat

    SciTech Connect

    Anzueto Hernandez, L.; Kvietys, P.R.; Granger, D.N.

    1986-07-01

    The postprandial intestinal hyperemia was studied in conscious and anesthetized rats using the radioactive microsphere technique. Carbohydrate, protein, lipid, and mixed meals, and the vehicle (Tyrode's solution), were placed in the stomach via a gastrostomy tube. In conscious rats, blood flow increased by 40-80% in the duodenum and jejunum 1 h after either a carbohydrate, lipid, protein, or mixed meal. Tyrode's solution produced a comparable hyperemia. Blood flow in the distal bowel segments (ileum, cecum, and colon) was significantly increased only by Tyrode's solution and the carbohydrate meal. The proximal intestinal hyperemia produced by the mixed meal in conscious animals was significantly attenuated by vagotomy yet unaltered by atropine pretreatment. In contrast to the results obtained from conscious rats, the mixed meal did not significantly alter intestinal blood flow in anesthetized animals. The results of this study indicate that the postprandial intestinal hyperemia is much greater in conscious than anesthetized animals. This difference may result from the higher resting blood flows in the latter group. The hyperemic response in conscious animals may be mediated by the vagus nerve.

  3. 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.

  4. 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.

  5. Predisposition to essential hypertension and renal hemodynamics in recent-onset insulin-dependent diabetic patients.

    PubMed

    Hannedouche, T P; Marques, L P; Guicheney, P; Lacour, B; Boitard, C; Grünfeld, J P

    1992-10-01

    The offspring of essential hypertensive parents have been found to exhibit abnormalities in renal hemodynamics and sodium handling before the eventual occurrence of hypertension. The reported abnormalities represent a wide spectrum of changes including increased GFR, normal or decreased RPF, slight increase in blood pressure (although within the normal range), and an exaggerated natriuresis response to a sodium load. The heterogeneity of these abnormalities may reflect the specific conditions of the studies, the lability of the changes, or different subgroups of subjects with genetic predisposition to essential hypertension. Several lines of evidence have suggested a relationship between hypertension and the development of diabetic nephropathy in insulin-dependent diabetics. This laboratory has found that recent-onset insulin-dependent diabetics can exhibit renal hemodynamics abnormalities very early in the course of diabetes according to a positive or negative family history of essential hypertension. These changes include increased GFR and mean arterial pressure, but no differences in renal sodium and lithium handling in diabetics with a genetic predisposition to essential hypertension. In addition, diabetics with a positive family history of essential hypertension exhibited a more-marked vasodilative response to an acute interruption of the renin-angiotensin system, further suggesting inadequate angiotensin modulation of renal vascular tone. The significance of these abnormalities in relation to the development of diabetic nephropathy requires further investigation.

  6. Numerical modeling of hemodynamics scenarios of patient-specific coronary artery bypass grafts.

    PubMed

    Ballarin, Francesco; Faggiano, Elena; Manzoni, Andrea; Quarteroni, Alfio; Rozza, Gianluigi; Ippolito, Sonia; Antona, Carlo; Scrofani, Roberto

    2017-03-13

    A fast computational framework is devised to the study of several configurations of patient-specific coronary artery bypass grafts. This is especially useful to perform a sensitivity analysis of the hemodynamics for different flow conditions occurring in native coronary arteries and bypass grafts, the investigation of the progression of the coronary artery disease and the choice of the most appropriate surgical procedure. A complete pipeline, from the acquisition of patient-specific medical images to fast parameterized computational simulations, is proposed. Complex surgical configurations employed in the clinical practice, such as Y-grafts and sequential grafts, are studied. A virtual surgery platform based on model reduction of unsteady Navier-Stokes equations for blood dynamics is proposed to carry out sensitivity analyses in a very rapid and reliable way. A specialized geometrical parameterization is employed to compare the effect of stenosis and anastomosis variation on the outcome of the surgery in several relevant cases.

  7. 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

  8. 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.

  9. [The hemodynamic characterization of the diabetic patient with arterial calcifications].

    PubMed

    Vega Gómez, M E; Ley Pozo, J; Aldama Figueroa, A; Lima Santana, B; Montalvo Diago, J; Bustillo, C; Fernández Boloña, A; Gutiérrez Jiménez, O; Ramirez Muñoz, O; Martínez Hernández, R

    1993-01-01

    This study was designed to describe the presence of calcifications according to the clinical features of the diabetic patient and the hemodynamics of the calcified arteries. With this purpose, 197 lower limbs from diabetic patients (type I and II) and carbon-hydrate intolerant patients, were studied. In all of the patients, the pressure ratio leg/arm was measured. On the same way, the arterial flow velocity was recorded using the Doppler ultrasonography on the pedia and postero-tibial arteries. The arterial calcifications, evident on the radiography of the foot, were more frequent between the type I patients and the neuro-infections diabetic foot. According to the hemodynamics point of view, we found a trend of association of more pathologic arterial flow velocity curves with the presence of calcifications (specially on the intima layer). It was also remarkable that an arterial incomprensibility was always associated with arterial calcifications.

  10. 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.

  11. A numerical hemodynamic tool for predictive vascular surgery.

    PubMed

    Marchandise, Emilie; Willemet, Marie; Lacroix, Valérie

    2009-01-01

    We suggest a new approach to peripheral vascular bypass surgery planning based on solving the one-dimensional (1D) governing equations of blood flow in patient-specific models. The aim of the present paper is twofold. First, we present the coupled 1D-0D model based on a discontinuous Galerkin method in a comprehensive manner, such as it becomes accessible to a wider community than the one of mathematicians and engineers. Then we show how this model can be applied to predict hemodynamic parameters and help therefore clinicians to choose for the best surgical option bettering the hemodynamics of a bypass. After presenting some benchmark problems, we apply our model to a real-life clinical application, i.e. a femoro-popliteal bypass surgery. Our model shows good agreement with preoperative and intraoperative measurements of velocity and pressure and post-surgical reports.

  12. Leg vein hemodynamics during bedrests simulating lunar trip.

    PubMed

    Louisy, F; Guezennec, C Y; Güell, A

    1994-05-01

    When contemplating future trips to the Moon whose gravity is one sixth of Earth gravity, the question is to know what the adaptive changes in the lower limb venous system would be. In fact, one can suppose that the presence of a partial gravity on the Moon would be able to attenuate venous hemodynamics adaptative changes observed in microgravity. In the present experiment changes in the venous hemodynamics of lower limbs have been studied with mercury strain gauge plethysmography during a simulated Moon mission including a 4 day trip to the Moon (-6 degrees bedrest), a stay of 6 days on the Moon (+11 degrees bedrest), and a 4-day trip back to Earth (-6 degrees bedrest). It was previously demonstrated that +11 degrees bedrest was a good model to simulate the effects of lunar gravity on the cardiovascular system (Vernikos-Danellis J 1986, personnal communication).

  13. Hemodynamic effects of acute digitalization several months after acute myocardial infarction.

    PubMed

    Ressl, J; Jandová, R; Jebavý, P; Kasalický, J; Widimský, J

    1975-01-01

    Left ventricular function was investigated at rest and during exercise by heart catheterization in 15 patients 3-5 months after acute myocardial infarction. The effect of 1 mg digoxin i.v. in ten patients was correlated to placebo (saline solution) in five patients. A significant decrease of the left ventricular enddiastolic pressure, increase of left ventricular systolic ejection fraction and a shift of the left ventricular function curve to left upwards was found after digoxin with no changes in the placebo group. This beneficial effect of acute digitalization in patients convalescing from uncomplicated myocardial infarction without clinical signs of manifest heart failure could have therapeutic implication.

  14. 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.

  15. Combined Visualization of Vessel Deformation and Hemodynamics in Cerebral Aneurysms.

    PubMed

    Meuschke, Monique; Voss, Samuel; Beuing, Oliver; Preim, Bernhard; Lawonn, Kai

    2017-01-01

    We present the first visualization tool that combines patient-specific hemodynamics with information about the vessel wall deformation and wall thickness in cerebral aneurysms. Such aneurysms bear the risk of rupture, whereas their treatment also carries considerable risks for the patient. For the patient-specific rupture risk evaluation and treatment analysis, both morphological and hemodynamic data have to be investigated. Medical researchers emphasize the importance of analyzing correlations between wall properties such as the wall deformation and thickness, and hemodynamic attributes like the Wall Shear Stress and near-wall flow. Our method uses a linked 2.5D and 3D depiction of the aneurysm together with blood flow information that enables the simultaneous exploration of wall characteristics and hemodynamic attributes during the cardiac cycle. We thus offer medical researchers an effective visual exploration tool for aneurysm treatment risk assessment. The 2.5D view serves as an overview that comprises a projection of the vessel surface to a 2D map, providing an occlusion-free surface visualization combined with a glyph-based depiction of the local wall thickness. The 3D view represents the focus upon which the data exploration takes place. To support the time-dependent parameter exploration and expert collaboration, a camera path is calculated automatically, where the user can place landmarks for further exploration of the properties. We developed a GPU-based implementation of our visualizations with a flexible interactive data exploration mechanism. We designed our techniques in collaboration with domain experts, and provide details about the evaluation.

  16. Neural correlates of single vessel hemodynamic responses in vivo

    PubMed Central

    O'Herron, Philip; Chhatbar, Pratik Y; Levy, Manuel; Shen, Zhiming; Schramm, Adrien E; Lu, Zhongyang; Kara, Prakash

    2016-01-01

    Neural activation increases blood flow locally. This vascular signal is used by functional imaging techniques to infer the location and strength of neural activity1,2. However, the precise spatial scale over which neural and vascular signals are correlated is unknown. Furthermore, the relative role of synaptic and spiking activity in driving hemodynamic signals is controversial3-9. Prior studies recorded local field potentials (LFPs) as a measure of synaptic activity together with spiking activity and low-resolution hemodynamic imaging. Here we used two-photon microscopy to measure sensory-evoked responses of individual blood vessels (dilation, blood velocity) while imaging synaptic and spiking activity in the surrounding tissue using fluorescent glutamate and calcium sensors. In cat primary visual cortex, where neurons are clustered by their preference for stimulus orientation, we discovered new maps for excitatory synaptic activity, which were organized similar to spiking activity but were less selective for stimulus orientation and direction. We generated tuning curves for individual vessel responses for the first time and found that parenchymal vessels in cortical layer 2/3 were orientation selective. Neighboring penetrating arterioles had different orientation preferences. Pial surface arteries in cats, as well as surface arteries and penetrating arterioles in rat visual cortex (where orientation maps do not exist10), responded to visual stimuli but had no orientation selectivity. We integrated synaptic or spiking responses around individual parenchymal vessels in cats and established that the vascular and neural responses had the same orientation preference. However, synaptic and spiking responses were more selective than vascular responses—vessels frequently responded robustly to stimuli that evoked little to no neural activity in the surrounding tissue. Thus, local neural and hemodynamic signals were partly decoupled. Together, these results indicate that

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Left Ventricular Mass: Correlation with Fatness, Hemodynamics and Renal Morphology

    PubMed Central

    Wykrętowicz, Mariusz; Katulska, Katarzyna; Milewska, Agata; Krauze, Tomasz

    2014-01-01

    Summary Background Left ventricular mass (LVM) is correlated with body composition and central hemodynamics as well as kidney function. Recently, fat-free mass has been considered to be more strongly correlated with LVM in comparison to other descriptors of fatness. We therefore address the question of whether comprehensive descriptors of fatness, central hemodynamics and renal characteristics demonstrate the association with left ventricular mass in healthy non-obese population. Material/Methods 119 healthy non-obese subjects (53 females, 66 males, mean age 50 yrs) were evaluated. Central hemodynamics was measured by Pulse Wave Analysis, left ventricular mass was assessed by echocardiography, fatness was evaluated by anthropometry, bioimpedance, and ultrasound. Results Left ventricular mass index (LVMI) correlated to the same extent with central and peripheral blood pressure but not with descriptors of wave reflection. Fat-free mass as well as intraabdominal fat correlated to a similar extent with LVMI. Kidney morphological characteristics indexed to body surface area were associated inversely and independently with LVMI. Conclusions Comprehensive assessment of fatness reinforced the concept that intraabdominal fat compartment is strongly correlated with left ventricular mass. Descriptors of wave reflection are not associated with left ventricular mass. The interrelationsh between kidney morphology and LVMI indicates that such associations may be a biologically plausible phenomenon. PMID:25436020

  2. [Study on Indicator Densitometry Determination Method of Hemodynamic Parameters].

    PubMed

    Liu, Guang-da; Zhou, Run-dong; Zha, Yu-tong; Cai, Jing; Niu, Jun-qi; Gao, Pu-jun; Liu, Li-li

    2016-03-01

    Measurement for hemodynamic parameters has always been a hot spot of clinical research. Methods for measuring hemodynamic parameters clinically have the problems of invasiveness, complex operation and being unfit for repeated measurement. To solve the problems, an indicator densitometry analysis method is presented based on near-infrared spectroscopy (NIRS) and indicator dilution theory, which realizes the hemodynamic parameters measured noninvasively. While the indocyanine green (ICG) was injected into human body, circulation carried the indicator mixing and diluting with the bloodstream. Then the near-nfrared probe was used to emit near-infrared light at 735, 805 and 940 nm wavelengths through the sufferer's fingertip and synchronously capture the transmission light containing the information of arterial pulse wave. By uploading the measured data, the computer would calculate the ICG concentration, establish continuous concentration curve and compute some intermediate variables such as the mean transmission time (MTT) and the initial blood ICG concentration (c(t0)). Accordingly Cardiac Output (CO) and Circulating Blood Volume (CBV) could be calculated. Compared with the clinical "gold standard" methods of thermodilution and I-131 isotope-labelling method to measure the two parameters by clinical controlled trials, ten sets of data were obtained. The maximum relative errors of this method were 8.88% and 4.28% respectively, and both of the average relative errors were below 5%. The result indicates that this method can meet the clinical accuracy requirement and can be used as a noninvasive, repeatable and applied solution for clinical hemodynamnic parameters measurement.

  3. 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.

  4. 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.

  5. 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.

  6. Differences in the Pulsatile Component of the Skin Hemodynamic Response to Verbal Fluency Tasks in the Forehead and the Fingertip

    PubMed Central

    Takahashi, Toshimitsu; Takikawa, Yoriko; Kawagoe, Reiko

    2016-01-01

    Several studies have claimed that hemodynamic signals measured by near-infrared spectroscopy (NIRS) on the forehead exhibit different patterns during a verbal fluency task (VFT) in various psychiatric disorders, whereas many studies have noted that NIRS signals can reflect task-related changes in skin blood flow. If such a task-related skin hemodynamic response is also observed in the fingertip, a simpler biomarker may be developed. Furthermore, determining the difference in the response pattern may provide physiological insights into the condition. We found that the magnitude of the pulsatile component in skin hemodynamic signals increased on the forehead (p < 0.001 for N = 50, p = 0.073 for N = 8) but decreased on the fingertip (p < 0.001, N = 8) during the VFT, whereas the rate in both areas increased (p < 0.02, N = 8). We also did not find a repetition effect in both the rate and the magnitude on the fingertip, whereas the effect was present in the magnitude (p < 0.02, N = 8) but not in the rate on the forehead. These results suggest that the skin vasomotor system in the forehead could have a different vessel mechanism to psychological tasks compared to the fingertip. PMID:26905432

  7. 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

  8. Pharmacological profiling of the hemodynamic effects of cannabinoid ligands: a combined in vitro and in vivo approach

    PubMed Central

    Walsh, Sarah K; Hepburn, Claire Y; Keown, Oliver; Åstrand, Annika; Lindblom, Anna; Ryberg, Erik; Hjorth, Stephan; Leslie, Stephan J; Greasley, Peter J; Wainwright, Cherry L

    2015-01-01

    The receptors mediating the hemodynamic responses to cannabinoids are not clearly defined due to the multifarious pharmacology of many commonly used cannabinoid ligands. While both CB1 and TRPV1 receptors are implicated, G protein-coupled receptor 55 (GPR55) may also mediate some of the hemodynamic effects of several atypical cannabinoid ligands. The present studies attempted to unravel the pharmacology underlying the in vivo hemodynamic responses to ACEA (CB1 agonist), O-1602 (GPR55 agonist), AM251 (CB1 antagonist), and cannabidiol (CBD; GPR55 antagonist). Agonist and antagonist profiles of each ligand were determined by ligand-induced GTPγS binding in membrane preparations expressing rat and mouse CB1 and GPR55 receptors. Blood pressure responses to ACEA and O-1602 were recorded in anesthetized and conscious mice (wild type, CB1−/− and GPR55−/−) and rats in the absence and presence of AM251 and CBD. ACEA demonstrated GTPγS activation at both receptors, while O-1602 only activated GPR55. AM251 exhibited antagonist activity at CB1 and agonist activity at GPR55, while CBD demonstrated selective antagonist activity at GPR55. The depressor response to ACEA was blocked by AM251 and attenuated by CBD, while O-1602 did not induce a depressor response. AM251 caused a depressor response that was absent in GPR55−/− mice but enhanced by CBD, while CBD caused a small vasodepressor response that persisted in GPR55−/− mice. Our findings show that assessment of the pharmacological profile of receptor activation by cannabinoid ligands in in vitro studies alongside in vivo functional studies is essential to understand the role of cannabinoids in hemodynamic control. PMID:26236485

  9. 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.

  10. 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

  11. Pneumatic compression hemodynamics in total hip arthroplasty.

    PubMed

    Westrich, G H; Specht, L M; Sharrock, N E; Sculco, T P; Salvati, E A; Pellicci, P M; Trombley, J F; Peterson, M

    2000-03-01

    A crossover study was performed to evaluate the effect of several pneumatic compression devices and active dorsoplantar flexion in 10 patients who underwent total hip arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5-MHz linear array probe, peak venous velocity and venous volume were assessed above and below the greater saphenous vein and common femoral vein junction. A computer generated randomization table was used to determine the order of the test conditions. The pneumatic compression devices evaluated included two foot pumps, one foot and calf pump, one calf pump, and three calf and thigh pumps. Statistical analyses included analysis of variance and analysis of variance with covariance between devices and patients. The covariates tested were the baseline measurements and the order in which the devices were tested. Differences between devices relate in part to the frequency and rate of inflation and the location and type of compression. Pulsatile calf and foot and calf pneumatic compression with a rapid inflation time produced the greatest increase in peak venous velocity, whereas compression of the calf and thigh showed the greatest increase in venous volume. Because patient and nursing compliance is essential to the success of mechanical prophylaxis for thromboembolic disease, the more simple, yet efficacious, devices that are easier to apply and less cumbersome appear to have a greater likelihood of success. In the active and alert patient, active dorsoplantar flexion should be encouraged.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. Hemodynamic effects of intra-aortic balloon counterpulsation in patients with acute myocardial infarction complicated by cardiogenic shock: the prospective, randomized IABP shock trial.

    PubMed

    Prondzinsky, Roland; Unverzagt, Susanne; Russ, Martin; Lemm, Henning; Swyter, Michael; Wegener, Nikolas; Buerke, Ute; Raaz, Uwe; Ebelt, Henning; Schlitt, Axel; Heinroth, Konstantin; Haerting, Johannes; Werdan, Karl; Buerke, Michael

    2012-04-01

    We conducted the IABP Cardiogenic Shock Trial (ClinicalTrials.gov ID NCT00469248) as a prospective, randomized, monocentric clinical trial to determine the hemodynamic effects of additional intra-aortic balloon pump (IABP) treatment and its effects on severity of disease in patients with acute myocardial infarction complicated by cardiogenic shock (CS). Intra-aortic balloon pump counterpulsation is recommended in patients with CS complicating myocardial infarction. However, there are only limited randomized controlled trial data available supporting the efficacy of IABP following percutaneous coronary intervention (PCI) and its impact on hemodynamic parameters in patients with CS. Percutaneous coronary intervention of infarct-related artery was performed in 40 patients with acute myocardial infarction complicated by CS, within 12 h of onset of hemodynamic instability. Serial hemodynamic parameters were determined over the next 4 days and compared in patients receiving medical treatment alone with those treated with additional intra-aortic balloon counterpulsation. There were no significant differences among severity of disease (i.e., Acute Physiology and Chronic Health Evaluation II score) initially and no differences among both groups for disease improvement. We observed significant temporal improvements of cardiac output (4.8 ± 0.5 to 6.0 ± 0.5 L/min), systemic vascular resistance (926 ± 73 to 769 ± 101 dyn · s(-1) · cm(-5)), and the prognosis-validated cardiac power output (0.78 ± 0.06 to 1.01 ± 0.2 W) within the IABP group. However, there were no significant differences between the IABP group and the medical-alone group. Additional IABP treatment did not result in a significant hemodynamic improvement compared with medical therapy alone in a randomized prospective trial in patients with CS following PCI. Therefore, the use and recommendation for IABP treatment in CS remain unclear.

  17. Moderate exercise training does not worsen left ventricle remodeling and function in untreated severe hypertensive rats.

    PubMed

    Boissiere, Julien; Eder, Véronique; Machet, Marie-Christine; Courteix, Daniel; Bonnet, Pierre

    2008-02-01

    Exercise training and hypertension induced cardiac hypertrophy but modulate differently left ventricle (LV) function. This study set out to evaluate cardiac adaptations induced by moderate exercise training in normotensive and untreated severe hypertensive rats. Four groups of animals were studied: normotensive (Ctl) and severe hypertensive (HT) Wistar rats were assigned to be sedentary (Sed) or perform a moderate exercise training (Ex) over a 10-wk period. Severe hypertension was induced in rat by a two-kidney, one-clip model. At the end of the training period, hemodynamic parameters and LV morphology and function were assessed using catheterism and conventional pulsed Doppler echocardiography. LV histology was performed to study fibrosis infiltrations. Severe hypertension increased systolic blood pressure to 202 +/- 9 mmHg and induced pathological hypertrophy (LV hypertrophy index was 0.34 +/- 0.02 vs. 0.44 +/- 0.02 in Ctl-Sed and HT-Sed groups, respectively) with LV relaxation alteration (early-to-atrial wave ratio = 2.02 +/- 0.11 vs. 1.63 +/- 0.12). Blood pressure was not altered by exercise training, but arterial stiffness was reduced in trained hypertensive rats (pulse pressure was 75 +/- 7 vs. 62 +/- 3 mmHg in HT-Sed and HT-Ex groups, respectively). Exercise training induced eccentric hypertrophy in both Ex groups by increasing LV cavity without alteration of LV systolic function. However, LV hypertrophy index was significantly decreased in normotensive rats only (0.34 +/- 0.02 vs. 0.30 +/- 0.02 in Ctl-Sed and Ctl-Ex groups, respectively). Moreover, exercise training improved LV passive filling in Ctl-Ex rats but not in Ht-Ex rats. In this study, exercise training did not reduce blood pressure and induced an additional physiological hypertrophy in untreated HT rats, which was slightly blunted when compared with Ctl rats. However, cardiac function was not worsened by exercise training.

  18. Neural and Hemodynamic Responses Elicited by Forelimb- and Photo-stimulation in Channelrhodopsin-2 Mice: Insights into the Hemodynamic Point Spread Function

    PubMed Central

    Vazquez, Alberto L.; Fukuda, Mitsuhiro; Crowley, Justin C.; Kim, Seong-Gi

    2014-01-01

    Hemodynamic responses are commonly used to map brain activity; however, their spatial limits have remained unclear because of the lack of a well-defined and malleable spatial stimulus. To examine the properties of neural activity and hemodynamic responses, multiunit activity, local field potential, cerebral blood volume (CBV)-sensitive optical imaging, and laser Doppler flowmetry were measured from the somatosensory cortex of transgenic mice expressing Channelrhodopsin-2 in cortex Layer 5 pyramidal neurons. The magnitude and extent of neural and hemodynamic responses were modulated using different photo-stimulation parameters and compared with those induced by somatosensory stimulation. Photo-stimulation-evoked spiking activity across cortical layers was similar to forelimb stimulation, although their activity originated in different layers. Hemodynamic responses induced by forelimb- and photo-stimulation were similar in magnitude and shape, although the former were slightly larger in amplitude and wider in extent. Altogether, the neurovascular relationship differed between these 2 stimulation pathways, but photo-stimulation-evoked changes in neural and hemodynamic activities were linearly correlated. Hemodynamic point spread functions were estimated from the photo-stimulation data and its full-width at half-maximum ranged between 103 and 175 µm. Therefore, submillimeter functional structures separated by a few hundred micrometers may be resolved using hemodynamic methods, such as optical imaging and functional magnetic resonance imaging. PMID:23761666

  19. 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,…

  20. 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…

  1. Percutaneous Hemodynamic Support (Impella) in Patients with Advanced Heart Failure and/or Cardiogenic Shock Not Eligible to PROTECT II Trial.

    PubMed

    Liu, Wei; Mukku, Venkata Kishore; Gilani, Syed; Fujise, Ken; Barbagelata, Alejandro

    2013-12-01

    PROTECT I and II trials have tested the efficacy of Impella in patents with high-risk percutaneous coronary intervention (PCI). However, patients with severe hemodynamic instability such as cardiac arrest, ST-segment elevated myocardial infarction (STEMI), or cardiogenic shock were excluded. The objective was to investigate the efficacy of Impella in sicker patient population who were not included in PROTECT trials. These patients merit high-risk PCI who had cardiogenic shock and unstable or decompensated heart failure (HF). From December 2010 to March 2012, 10 consecutive patients with extremely high surgical risk and hemodynamic instability underwent urgent PCI with Impella 2.5 support (Abiomed Inc., Danvers, MA). These patients were presented with advance HF and/or cardiogenic shock. Among the 10 included patients, 3 patients were with cardiac arrest and 1 patient was with acute myocardial infarction. All patients had successful Impella implantation and remained hemodynamically stable during high-risk PCI. Among the 10 patients 2 patients (20%) died within 1 month and 1 patient developed limb ischemia. In high-risk population nonrandomizable to PROTECT trials with advance HF/cardiogenic shock, Impella could be an important tool for hemodynamic support to PCI or could be a bridge to left ventricle assist device to achieve good recovery. Larger studies need to be conducted on this high-risk population.

  2. Axial penile rigidity: determinants and relation to hemodynamic parameters.

    PubMed

    Goldstein, I; Udelson, D

    1998-05-01

    Erectile dysfunction may be defined in terms of axial penile rigidity, the physical property that enables the erection to be utilized as a penetration tool during sexual activity. Erectile dysfunction occurs when inadequate axial penile rigidity results in buckling of the penile column when subjected to axial compressive loading situations during vaginal intromission. New multi-disciplinary engineering studies of penile hemodynamic and structural dynamic relationships are reviewed concerning the determinants of axial penile rigidity. Axial penile rigidity develops as a continuum during the increases in intracavernosal pressure and volume changes from the flaccid state and is influenced by intracavernosal pressure, penile tissue mechanical properties and penile geometry. Two penile tissue mechanical properties are especially relevant; cavernosal maximum volume at relatively low intracavernosal pressure, and tunical distensibility, the relative volume of the fully erect to completely flaccid pendulous penis. Two penile geometric properties are critical; the penile aspect ratio, defined as the diameter to length ratio of the pendulous penis, and the magnitude of the flaccid penile diameter. Clinically measured values of axial buckling forces in patients undergoing dynamic pharmacocavernosometry strongly correlated to theoretic-based analytic derived magnitudes of axial penile rigidity based on these above pressure, tissue and geometric determinants. Since axial penile rigidity is not exclusively dependent upon intracavernosal pressure, patients with normal erectile hemodynamics may be erroneously labelled as having psychogenic dysfunction where their true pathophysiology may be related to abnormal penile tissue properties and/or penile geometric factors. Similarly, some patients may claim sufficient rigidity for penetration, but have abnormal hemodynamic erectile function studies. They may have uniquely advantageous tissue mechanical and/or geometric properties. More

  3. 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

  4. 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.

  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.

  6. Clitoral hemodynamic changes after a topical application of alprostadil.

    PubMed

    Becher, E F; Bechara, A; Casabe, A

    2001-01-01

    We performed duplex ultrasonography of the clitoris to assess the local hemodynamic changes after a topical application of alprostadil. Color duplex ultrasonography was used to evaluate 18 women before and after the application of 1 g of 0.2% alprostadil gel. The peak systolic velocity and end diastolic velocity showed a statistically significant difference after the application. All women showed labial and clitoral engorgement, 72% reported a pleasant sensation of warmth, and no systemic side effects were found. These findings are similar to the values reported after sexual stimulation, indicating that topical vasoactive drugs might help in the differential diagnosis of the vascular component of female sexual dysfunction.

  7. Mathematical modeling of renal hemodynamics in physiology and pathophysiology.

    PubMed

    Sgouralis, Ioannis; Layton, Anita T

    2015-06-01

    In addition to the excretion of metabolic waste and toxin, the kidney plays an indispensable role in regulating the balance of water, electrolyte, acid-base, and blood pressure. For the kidney to maintain proper functions, hemodynamic control is crucial. In this review, we describe representative mathematical models that have been developed to better understand the kidney's autoregulatory processes. We consider mathematical models that simulate glomerular filtration, and renal blood flow regulation by means of the myogenic response and tubuloglomerular feedback. We discuss the extent to which these modeling efforts have expanded the understanding of renal functions in health and disease.

  8. 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

  9. 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.

  10. Effect of Arched Leaflets and Stent Profile on the Hemodynamics of Tri-Leaflet Flexible Polymeric Heart Valves.

    PubMed

    Yousefi, Atieh; Bark, David L; Dasi, Lakshmi P

    2017-02-01

    Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations. Three models were created with height to diameter ratio of 0.6, 0.7, and 0.88. The other three models were designed by altering arch height to stent diameter ratio, to be 0, 0.081, and 0.116. Particle image velocimetry experiments were conducted on each PHV to characterize velocity, vorticity, turbulent characteristics, effective orifice area, and regurgitant fraction. This study revealed that the presence of arches as well as higher stent profile reduced regurgitant flow down to 5%, while peak systole downstream velocity reduced to 58% and Reynolds Shear Stress values reduced 40%. Further, earlier reattachment of the forward flow jet was observed in PHVs with leaflet arches. These findings indicate that although both geometric factors help diminish the commissural gap during diastole, leaflet arches induce a larger jet opening, yielding to earlier flow reattachment and lower energy dissipation.

  11. 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

  12. The multiple parameter hemodynamic imaging system based on ARM

    NASA Astrophysics Data System (ADS)

    Tang, Xuejun; He, Heng; Jiang, Chao; Li, Pengcheng; Luo, Qingming

    2008-12-01

    Optical imaging with high resolution is significant to reveal the functional activities of brain and the mechanism of disease, and has grown into a diverse field. The high-resolution multi-parameters optical imaging system which combines the laser speckle contrast imaging method and optical intrinsic signal imaging method can obtain more hemodynamic information in cortex simultaneously. However, most of current optical imaging systems use He-Ne laser and mercury xenon arc lamp as the light source. Meanwhile, the control unit of the system which includes a personal computer, is not portable. In this paper, we develop a multiple parameters hemodynamic imaging system based on ARM. To make the system more compact, three wavelengths light-emitting diode and laser diode as imaging illuminants were adopted. In addition, the real-time embedded operation system (μC/OS-II) and embedded Graphic User Interface (μC/GUI) were introduced. Animal experimental results also show that changes in oxyhemoglobin, deoxyhemoglobin, total hemoglobin concentration and cerebral blood flow during Cortical Spreading Depression can be simultaneously accessed using this optical imaging system based on embedded ARM.

  13. 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.

  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.

  15. Neuronal or hemodynamic? Grappling with the functional MRI signal.

    PubMed

    Bandettini, Peter A

    2014-09-01

    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.

  16. Coronary Flow Impacts Aortic Leaflet Mechanics and Aortic Sinus Hemodynamics.

    PubMed

    Moore, Brandon L; Dasi, Lakshmi Prasad

    2015-09-01

    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.

  17. Immediate hemodynamic response to furosemide in patients undergoing chronic hemodialysis.

    PubMed

    Schmieder, R E; Messerli, F H; deCarvalho, J G; Husserl, F E

    1987-01-01

    To evaluate the effect of furosemide on cardiovascular hemodynamics in patients with end-stage renal failure, we studied ten patients undergoing hemodialysis three times a week. Arterial pressure, heart rate, and cardiac output (indocyanine green dye) were measured in triplicate; total peripheral resistance and central blood volume were calculated by standard formulas. Hemodynamics were determined at baseline and 5, 10, 15, and 30 minutes after intravenous (IV) bolus injection of furosemide 60 mg. Furosemide produced a decrease in central blood volume of -13% +/- 2.2% from pretreatment values (P less than .01) that was most pronounced five minutes after injection, together with a fall in cardiac output (from 6.76 +/- 0.59 to 6.17 +/- 0.52 L/min, P less than .10). Stroke volume decreased with a maximum fall occurring after 15 minutes (from 84 +/- 7 to 79 +/- 7 mL/min, P less than .05), and total peripheral resistance increased (from 15.8 +/- 2.1 to 17.8 +/- 2.3 units, P less than .05) after furosemide. Arterial pressure and heart rate did not change. The decrease in central blood volume reflects a shift of the total blood volume from the cardiopulmonary circulation to the periphery, suggesting dilation of the peripheral venous bed. Thus, even in patients undergoing hemodialysis, furosemide acutely decreases left ventricular preload by venous dilation and should therefore prove to be beneficial in acute volume overload.

  18. Antiangiogenic factors and maternal hemodynamics during intensive hemodialysis in pregnancy.

    PubMed

    Cornelis, Tom; Spaanderman, Marc; Beerenhout, Charles; Perschel, Frank H; Verlohren, Stefan; Schalkwijk, Casper G; van der Sande, Frank M; Kooman, Jeroen P; Hladunewich, Michelle

    2013-10-01

    We report on a 21-year-old pregnant patient with IgA nephropathy who was initiated on intensive hemodialysis (8 hours of hemodialysis 3 times a week) at a gestational age of 26 weeks on the basis of worsening kidney function resulting in rapidly progressive fatigue and difficulties in metabolic control. Throughout the pregnancy, and while on intensive hemodialysis, 24-hour ambulatory blood pressure control was within the target, and results of weekly 24-hour measurement of central hemodynamics and pulse wave velocity, and of serial levels of circulating (anti-)angiogenic factors were comparable to normal pregnancies. Estimated fetal growth evolved along the 50th percentile, and no polyhydramnios was detected. After induction for a sudden, unexplained increase in blood pressure, she delivered a healthy boy of 2480 g at a gestational age of 36 weeks. This case adds to the expanding literature that supports the use of intensive hemodialysis in pregnant patients with end-stage renal disease and illustrates, for the first time, the potential use of serial (anti-) angiogenic factors and 24-hour measurements of blood pressure and hemodynamic indices in order to facilitate monitoring of these complicated patients.

  19. [Hemodynamic Status of Prepubertal and Pubertal Hockey Players].

    PubMed

    Shayhelislamova, M V; Sitdikov, F G; Zefirov, T L; Dikopolskaya, N B

    2015-01-01

    The hemodynamic status of 11-15-year-old hockey players depending on their age and puberty stage were studied and compared with hemodynamic parameters of the control group. It was found that regular muscle training has a dominant effect on the functional state of cardiovascular system (CVS) in prepuberty and puberty. It was proved that in hockey players a decrease in the heart rate (H R) and an increase in the stroke volume (SV) result in a significant increase in systolic blood pressure (SBP) at the age of 11-14 years and a progressive increase in total peripheral vascular resistance (PVR), in contrast to significantly lower values in the control group. The urgent adaptation of CVS to graduated physical activities at the age of 11-13 years leads to an enhancement of vascular spasmodic reactions while SV remains constant. It was found that in adolescent hockey players have consistently high SV and SBP; at the same time, maximal values of HR, cardiac output (CO) and diastolic blood pressure (DBP) were observed at the stages I and II of the puberty period; then, at the stage III, these parameters decrease. I n the control group, hymodinamic status changed in an opposite way. This may be an evidence of the stress effect of physical activities which results in the adaptive reactions of CVS rather than reactions typical of the puberty period.

  20. 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.

  1. Cardiovascular and hemodynamic effects of glucagon-like peptide-1.

    PubMed

    Goodwill, Adam G; Mather, Kieren J; Conteh, Abass M; Sassoon, Daniel J; Noblet, Jillian N; Tune, Johnathan D

    2014-09-01

    Glucagon-like peptide-1 (GLP-1) is an incretin hormone that has been shown to have hemodynamic and cardioprotective capacity in addition to its better characterized glucoregulatory actions. Because of this, emerging research has focused on the ability of GLP-1 based therapies to drive myocardial substrate selection, enhance cardiac performance and regulate heart rate, blood pressure and vascular tone. These studies have produced consistent and reproducible results amongst numerous laboratories. However, there are obvious disparities in findings obtained in small animal models versus those of higher mammals. This species dependent discrepancy calls to question, the translational value of individual findings. Moreover, few studies of GLP-1 mediated cardiovascular action have been performed in the presence of a pre-existing comorbidities (e.g. obesity/diabetes) which limits interpretation of the effectiveness of incretin-based therapies in the setting of disease. This review addresses cardiovascular and hemodynamic potential of GLP-1 based therapies with attention to species specific effects as well as the interaction between therapies and disease.

  2. 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.

  3. 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.

  4. Renal Hemodynamics in AKI: In Search of New Treatment Targets

    PubMed Central

    Matejovic, Martin; Ince, Can; Chawla, Lakhmir S.; Blantz, Roland; Molitoris, Bruce A.; 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

  5. 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.

  6. Bedside calculation of hemodynamic parameters with a hand held programmable calculator. Part II: Programs for hemodynamic and oxygen transport parameters computation.

    PubMed

    Laurent, M

    1980-01-01

    Two programs calculating oxygen transport parameters and hemodynamic values respectively are described. They may be used indifferently with HP 67 or HP 97 Hewlett Packard calculators. (Acta anaesth. belg., 1980, 31, 53-59).

  7. Early Cerebral Hemodynamic, Metabolic, and Histological Changes in Hypoxic–Ischemic Fetal Lambs during Postnatal Life

    PubMed Central

    Rey-Santano, Carmen; Mielgo, Victoria E.; Gastiasoro, Elena; Murgia, Xabier; Lafuente, Hector; Ruiz-del-Yerro, Estibaliz; Valls-i-Soler, Adolf; Hilario, Enrique; Alvarez, Francisco J.

    2011-01-01

    The hemodynamic, metabolic, and biochemical changes produced during the transition from fetal to neonatal life may be aggravated if an episode of asphyxia occurs during fetal life. The aim of the study was to examine regional cerebral blood flow (RCBF), histological changes, and cerebral brain metabolism in preterm lambs, and to analyze the role of oxidative stress in the first hours of postnatal life following severe fetal asphyxia. Eighteen chronically instrumented newborn lambs were randomly assigned to either a control group or the hypoxic–ischemic (HI) group, in which case fetal asphyxia was induced just before delivery. All the animals were maintained on intermittent positive pressure ventilation for 3 h after delivery. During the HI insult, the injured group developed acidosis, hypoxia, hypercapnia, lactic acidosis, and tachycardia (relative to the control group), without hypotension. The intermittent positive pressure ventilation transiently improved gas exchange and cardiovascular parameters. After HI injury and during ventilatory support, there continued to be an increased RCBF in inner regions among the HI group, but no significant differences were detected in cortical flow compared to the control group. Also, the magnitude of the increase in TUNEL positive cells (apoptosis) and antioxidant enzymes, and decrease of ATP reserves was significantly greater in the brain regions where the RCBF was not higher. In conclusion, our findings identify early metabolic, histological, and hemodynamic changes involved in brain damage in premature asphyxiated lambs. Such changes have been described in human neonates, so our model could be useful to test the safety and the effectiveness of different neuroprotective or ventilation strategies applied in the first hours after fetal HI injury. PMID:21960958

  8. 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

  9. Glucose-insulin-potassium correlates with hemodynamic improvement in patients with septic myocardial dysfunction

    PubMed Central

    Kim, Won-Young; Baek, Moon Seong; Kim, Young Shin; Seo, Jarim; Huh, Jin Won; Lim, Chae-Man; Koh, Younsuck

    2016-01-01

    Background Glucose-insulin-potassium (GIK) demonstrates a cardioprotective effect by providing metabolic support and anti-inflammatory action, and may be useful in septic myocardial depression. The aim of this study was to examine the relationship between GIK and hemodynamic outcomes in septic shock patients with myocardial depression. Methods Between October 2012 and March 2014, 45 patients in the intensive care unit who fulfilled the criteria for severe sepsis/septic shock and were treated with GIK were recruited. Patients were divided into two groups according to echocardiographic findings: hypodynamic (27%) and non-hypodynamic (36%). Results Baseline vasopressor requirements did not differ between both groups. In 12 patients with hypodynamic septic shock with myocardial depression, mean arterial pressure (MAP) increased with the median [interquartile range (IQR)] area under the curve of 16 (8 to 29) mmHg, and the heart rate (HR) decreased with the median (IQR) area under the curve of −9 (−20 to 2)/min during the first 72 h. The total insulin dose correlated with improvement in MAP (r=0.61, P=0.061) and the cardiovascular Sequential Organ Failure Assessment score (r=−0.64, P=0.045) at 72 h, although this phenomenon was not observed in patients with non-hypodynamic septic shock. Serum glucose and potassium levels were within the target ranges in both groups during the 72-h study period. Conclusions Short-term improvement in hemodynamics correlated with GIK administration in septic shock patients with myocardial depression. The use of GIK was well tolerated in all patients. Further studies are required to demonstrate the role of GIK in septic myocardial dysfunction. PMID:28149560

  10. Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system.

    PubMed

    Choy, Jenny S; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease progression and

  11. Longitudinal Hemodynamic Measurements in Swine Heart Failure Using a Fully Implantable Telemetry System

    PubMed Central

    Choy, Jenny S.; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S.

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease

  12. Thoracic Aorta 3D Hemodynamics in Pediatric and Young Adult Patients With Bicuspid Aortic Valve

    PubMed Central

    Allen, Bradley D.; van Ooij, Pim; Barker, Alex J.; Carr, Maria; Gabbour, Maya; Schnell, Susanne; Jarvis, Kelly B.; Carr, James C.; Markl, Michael; Rigsby, Cynthia; Robinson, Joshua D.

    2015-01-01

    Background To evaluate the 3D hemodynamics in the thoracic aorta of pediatric and young adult bicuspid aortic valve (BAV) patients. Methods 4D flow MRI was performed in 30 pediatric and young adult BAV patients (age: 13.9 ± 4.4 (range: [3.4, 20.7]) years old, M:F = 17:13) as part of this Institutional Review Board-approved study. Nomogram-based aortic root Z-scores were calculated to assess aortic dilatation and degree of aortic stenosis (AS) severity was assessed on MRI. Data analysis included calculation of time-averaged systolic 3D wall shear stress (WSSsys) along the entire aorta wall, and regional quantification of maximum and mean WSSsys and peak systolic velocity (velsys) in the ascending aorta (AAo), arch, and descending aorta (DAo). The 4D flow MRI AAo velsys was also compared with echocardiography peak velocity measurements. Results There was a positive correlation with both mean and max AAo WSSsys and peak AAo velsys (mean: r = 0.84, P < 0.001, max: r = 0.94, P < 0.001) and AS (mean: rS = 0.43, P = 0.02, max: rS = 0.70, P < 0.001). AAo peak velocity was significantly higher when measured with echo compared with 4D flow MRI (2.1 ± 0.98 m/s versus 1.27 ± 0.49 m/s, P < 0.001). Conclusion In pediatric and young adult patients with BAV, AS and peak ascending aorta velocity are associated with increased AAo WSS, while aortic dilation, age, and body surface area do not significantly impact AAo hemodynamics. Prospective studies are required to establish the role of WSS as a risk-stratification tool in these patients. PMID:25644073

  13. 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.

  14. 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

  15. 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

  16. [Effect of complex sanatorium treatment including magnetotherapy on hemodynamics in patients with arterial hypertension].

    PubMed

    Efremushkin, G G; Duruda, N V

    2003-01-01

    Forty nine patients with arterial hypertension of stage I-II received combined sanatorium treatment. Of them, 21 had adjuvant total magnetotherapy. All the patients were examined for parameters of central, cerebral hemodynamics and microcirculation. The adjuvant magnetotherapy produced a beneficial effect on hypertension: clinical symptoms attenuated, arterial pressure became more stable, hemodynamics improved, duration of hospitalization reduced, requirement in hypotensive drugs diminished.

  17. Hemodynamic measurements in rat brain combining diffuse near-infrared absorption and correlation spectroscopies

    NASA Astrophysics Data System (ADS)

    Yu, Guoqiang; Durduran, Turgut; Furuya, Daisuke; Greenberg, Joel H.; Yodh, Arjun G.

    2002-09-01

    Measurement of concentration, oxygenation, and flow characteristics of blood cells can reveal information about tissue metabolism and functional heterogeneity. An instrument has been built that combines two near-infrared diffuse optical techniques to simultaneously monitor blood flow, blood volume and blood oxygen saturation. 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 measured tissue absorption and scattering. The modularized design of the instrument provides the instrument great flexibility for trading off the temporal, spectral and spatial resolution by selecting the number of source-detector pairs and wavelengths. The frame acquisition rate of the current instrument is 0.2 Hz with 3l (wavelengths) x 15s (source positions) x 4d (detectors) for DPDW measurement in the frequency domain, and 1λ x 3s; x 9d for DCS. Higher frame acquisition rate could be achieved by reducing the spatial resolution, for example, 2 Hz with 3λ x 1s x 4d for DPDW and 1l x 1s x 9d for DCS. The unique non-contact probe mounted on the back of a camera allows non-contact measurement that avoids potentially altering blood flow. We used this instrument to monitor in vivo the hemodynamic responses in rat brain during KCl induced cortical spreading depression (CSD).

  18. Acute Cardiovascular and Hemodynamic Responses to Low Intensity Eccentric Resistance Exercise with Blood Flow Restriction

    PubMed Central

    Bazgir, Behzad; Rezazadeh Valojerdi, Mojtaba; Rajabi, Hamid; Fathi, Rouhollah; Ojaghi, Seyed Mojtaba; Emami Meybodi, Mohammad Kazem; Neto, Gabriel R.; Rahimi, Mostafa; Asgari, Alireza

    2016-01-01

    Background Recently it has been suggested that low intensity (LI) resistance exercise (RE) alone or in combination with blood flow restriction (BFR) can be applied for cardiovascular function improvement or rehabilitation. Objectives The aim of the present study was to investigate the acute effects of LI eccentric RE with and without BFR on heart rate (HR), rate pressure product (RPP), blood pressure (BP) parameters [systolic, diastolic, and mean arterial pressure (MAP)], oxygen saturation (SpO2) and rate of perceived exertion (RPE). Methods In a semi-experimental study 16 young adults (26.18 ± 3.67 years) volunteered and performed LI (30% maximum voluntary contraction) eccentric RE alone or combined with BFR. Results The results indicated that HR, RPP, and RPE increased significantly within both groups (P < 0.05); SBP and DBP increased significantly only with BFR (P < 0.05); MAP increased significantly during exercise without BFR (P < 0.05); and no change was observed in SpO2 in either groups (P > 0.05). Furthermore, studied parameters did not vary amongst different groups (P > 0.05). Conclusions It is concluded that LI eccentric RE with BFR positively regulated the hemodynamic and cardiovascular responses. Therefore, the eccentric RE combined with BFR seems to be a good option for future studies with the aim of time efficacy, since it alters these parameters within normal values. PMID:28144415

  19. [Pathogenic role of intracellular energy insufficiency (hypoenergy) in the development of circulatory collapse (hemodynamic shock)].

    PubMed

    Kovac, Z

    1995-06-01

    Hemodynamic shock syndrome represents an acute circulatory failure due to a decrease of arteriovenous pressure gradient. Three unrelated groups of processes, cardiogenic, vasohypotonic and hypovolemic mechanisms, are possible starting points of the shock syndrome pathogenesis. The basic features of those principal pathogenic steps are outlined in the paper. In addition, clinical practice very often encounters a complex forms of the syndrome, which include two or all three basic pathogenic mechanisms simultaneously. Direct consequence of arteriovenous pressure gradient loss is diminishing perfusion of tissues. Tissue hypoperfusion causes a progressive depletion of cellular energy rich compounds. Such lowering of cellular ATP concentration (cellular hypoenergosis), very often less than 0.1 mmol/L, plays an important pathogenic role in the conversion of homeostatic regulation processes from a negative into a positive feedback mode. Positive feedback regulation amplifies deterioration of arteriovenous blood pressure gradient loss, which reversely intensifies the degree of energy depletion in tissues. Individual cell death decreases a tissue adjustment capacity to hypoperfusion. The critical step leading to a decompensation (systemic failure) or progressive phase of the shock is the reversal of the homeostasis into the positive feedback mode of action. Final outcome of the syndrome reflects a degree of compensation capacity loss as well as irreversible tissue alterations. Clinical manifestations correlate with the underlying pathogenic processes. Short summary of clinical correlative relations with the pathogenic processes, at the cellular, molecular and/or energy level, is given in the paper.

  20. 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.

  1. Verification of a research prototype for hemodynamic analysis of cerebral aneurysms.

    PubMed

    Suzuki, Takashi; Ioan Nita, Cosmin; Rapaka, Saikiran; Takao, Hiroyuki; Mihalef, Viorel; Fujimura, Soichiro; Dahmani, Chihebeddine; Sharma, Puneet; Mamori, Hiroya; Ishibashi, Toshihiro; Redel, Thomas; Yamamoto, Makoto; Murayama, Yuichi

    2016-08-01

    Owing to its clinical importance, there has been a growing body of research on understanding the hemodynamics of cerebral aneurysms. Traditionally, this work has been performed using general-purpose, state-of-the-art commercial solvers. This has meant requiring engineering expertise for making appropriate choices on the geometric discretization, time-step selection, choice of boundary conditions etc. Recently, a CFD research prototype has been developed (Siemens Healthcare GmbH, Prototype - not for diagnostic use) for end-to-end analysis of aneurysm hemodynamics. This prototype enables anatomical model preparation, hemodynamic computations, advanced visualizations and quantitative analysis capabilities. In this study, we investigate the accuracy of the hemodynamic solver in the prototype against a commercially available CFD solver ANSYS CFX 16.0 (ANSYS Inc., Canonsburg, PA, www.ansys.com) retrospectively on a sample of twenty patient-derived aneurysm models, and show good agreement of hemodynamic parameters of interest.

  2. First implantable hemodynamic monitoring device placement in single ventricle fontan anatomy.

    PubMed

    Bradley, Elisa A; Berman, Darren; Daniels, Curt J

    2016-08-01

    The Fontan anatomy leads to elevated central venous pressure along with chronic venous congestion and low cardiac output; this is felt to be responsible for deterioration of exercise tolerance and functional capacity over time. Real-time hemodynamic evaluation of the Fontan anatomy has not been evaluated until now. Here, we report the technical aspects of the first two adult Fontan patients to undergo placement of an invasive hemodynamic monitor (IHM). We validate IHM readings with invasive pulmonary artery catheter derived hemodynamics in the Fontan and show successful home transmission of pulmonary artery hemodynamic tracings. This technology has the capacity to change current understanding of Fontan hemodynamics and treatment in patients with complex single-ventricle anatomy. © 2016 Wiley Periodicals, Inc.

  3. Sever's Disease

    MedlinePlus

    ... good flexibility while your child is growing. The stretching exercises pictured in the treatment section can lower ... your child has already recovered from Sever's disease, stretching and putting ice on the heel after activity ...

  4. Hemodynamic response to treatment of iron deficiency anemia in pulmonary arterial hypertension: longitudinal insights from an implantable hemodynamic monitor

    PubMed Central

    2016-01-01

    Abstract Despite new therapeutic options, pulmonary arterial hypertension (PAH) remains a progressive disease associated with substantial morbidity and mortality. As such, additional strategies for monitoring and adjunctive management of this disease are important. A 59-year-old woman with scleroderma-associated PAH received an implantable hemodynamic monitor (IHM) as part of a research protocol at our institution. Pulmonary artery pressures, heart rate, and cardiac output (sensor-based algorithm) were measured on a daily basis, and parameters of right ventricular (RV) performance and afterload were calculated. At the time of IHM implant, the patient had functional class III symptoms, was receiving triple-drug therapy, and had normal hemoglobin levels. Four months after implant, and with further optimization of prostacyclin therapy, she had improvement in her symptoms. However, shortly thereafter, while the patient was receiving stable drug therapy, her case regressed with worsening symptoms, and the patient received a new diagnosis of iron deficiency anemia. Oral iron supplementation resulted in normalization of hemoglobin levels and improvement in the patient’s iron profile. A gradual and sustained reduction in pulmonary pressures was noted after initiation of oral iron accompanied by increased RV performance and favorable reduction in RV afterload. The patient had significant symptomatic improvement. Iron deficiency is an underappreciated yet easily treatable risk factor in PAH. Use of IHM in this case longitudinally illustrates the optimization of pulmonary hemodynamics and RV afterload in tandem with clinical improvement achieved by a simple therapy. PMID:28090307

  5. Hemodynamic response to treatment of iron deficiency anemia in pulmonary arterial hypertension: longitudinal insights from an implantable hemodynamic monitor.

    PubMed

    Mehmood, Muddassir; Agarwal, Richa; Raina, Amresh; Correa-Jaque, Priscilla; Benza, Raymond L

    2016-12-01

    Despite new therapeutic options, pulmonary arterial hypertension (PAH) remains a progressive disease associated with substantial morbidity and mortality. As such, additional strategies for monitoring and adjunctive management of this disease are important. A 59-year-old woman with scleroderma-associated PAH received an implantable hemodynamic monitor (IHM) as part of a research protocol at our institution. Pulmonary artery pressures, heart rate, and cardiac output (sensor-based algorithm) were measured on a daily basis, and parameters of right ventricular (RV) performance and afterload were calculated. At the time of IHM implant, the patient had functional class III symptoms, was receiving triple-drug therapy, and had normal hemoglobin levels. Four months after implant, and with further optimization of prostacyclin therapy, she had improvement in her symptoms. However, shortly thereafter, while the patient was receiving stable drug therapy, her case regressed with worsening symptoms, and the patient received a new diagnosis of iron deficiency anemia. Oral iron supplementation resulted in normalization of hemoglobin levels and improvement in the patient's iron profile. A gradual and sustained reduction in pulmonary pressures was noted after initiation of oral iron accompanied by increased RV performance and favorable reduction in RV afterload. The patient had significant symptomatic improvement. Iron deficiency is an underappreciated yet easily treatable risk factor in PAH. Use of IHM in this case longitudinally illustrates the optimization of pulmonary hemodynamics and RV afterload in tandem with clinical improvement achieved by a simple therapy.

  6. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons

    PubMed Central

    Ma, Ying; Shaik, Mohammed A.; Kozberg, Mariel G.; Portes, Jacob P.; Timerman, Dmitriy

    2016-01-01

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI. PMID:27974609

  7. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons.

    PubMed

    Ma, Ying; Shaik, Mohammed A; Kozberg, Mariel G; Kim, Sharon H; Portes, Jacob P; Timerman, Dmitriy; Hillman, Elizabeth M C

    2016-12-27

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI.

  8. 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

  9. 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

  10. 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

  11. Hemodynamic and histomorphometric characteristics of dilated cardiomyopathy of Syrian hamsters (Bio TO-2 strain).

    PubMed

    Goineau, S; Pape, D; Guillo, P; Ramée, M P; Bellissant, E

    2001-04-01

    The natural history of the disease of the dilated strain Bio TO-2 of cardiomyopathic hamsters (CMH) is not totally characterized. We investigated its hemodynamic and histomorphometric characteristics at 140, 180, 220, 260, and 300 days of age. Forty CMH and 40 controls were investigated (8 at each stage). Mean arterial pressure (MAP, carotid artery catheter) and cardiac output and femoral blood flow (CO, FBF, transit time method) were measured in anesthetized animals. Systemic (SVR) and femoral (FVR) vascular resistances were calculated. Atria, left and right ventricles (LV, RV), lungs, and liver were weighed. LV cavity area, LV and RV wall thicknesses and collagen densities were determined (computer-assisted image analyzer). Pulmonary and hepatic congestion were assessed (arbitrary scales). Compared with controls, MAP, CO and FBF were significantly lower in CMH throughout the study (on average: -22%, -34%, -33%, respectively), FVR was significantly increased (+15%), but SVR was not significantly modified. Concerning histomorphometric characteristics, differences between groups significantly increased with age for most variables: at 300 days, atria (+292%), RV (+13%), lungs (+44%), and liver (+23%) weights, LV cavity area (+130%), LV (+364%) and RV (+181%) collagen densities were significantly increased in CMH vs controls, whereas LV (-40%) and RV (-23%) wall thicknesses were significantly decreased. At 260 and 300 days, CMH showed significant pulmonary congestion without hepatic alteration. Bio TO-2 CMH progressively develop an alteration of cardiac function leading to decreased MAP and musculo-cutaneous blood flow associated with cardiac remodeling including atria hypertrophy and LV dilation, wall thinning and a rise in collagen density.

  12. Genetic variant rs3750625 in the 3'UTR of ADRA2A affects stress-dependent acute pain severity after trauma and alters a microRNA-34a regulatory site.

    PubMed

    Linnstaedt, Sarah D; Walker, Margaret G; Riker, Kyle D; Nyland, Jennifer E; Hu, JunMei; Rossi, Catherine; Swor, Robert A; Jones, Jeffrey S; Diatchenko, Luda; Bortsov, Andrey V; Peak, David A; McLean, Samuel A

    2017-02-01

    α2A adrenergic receptor (α2A-AR) activation has been shown in animal models to play an important role in regulating the balance of acute pain inhibition vs facilitation after both physical and psychological stress. To our knowledge, the influence of genetic variants in the gene encoding α2A-AR, ADRA2A, on acute pain outcomes in humans experiencing traumatic stress has not been assessed. In this study, we tested whether a genetic variant in the 3'UTR of ADRA2A, rs3750625, is associated with acute musculoskeletal pain (MSP) severity following motor vehicle collision (MVC, n = 948) and sexual assault (n = 84), and whether this influence was affected by stress severity. We evaluated rs3750625 because it is located in the seed binding region of miR-34a, a microRNA (miRNA) known to regulate pain and stress responses. In both cohorts, the minor allele at rs3750625 was associated with increased musculoskeletal pain in distressed individuals (stress*rs3750625 P = 0.043 for MVC cohort and P = 0.007 for sexual assault cohort). We further found that (1) miR-34a binds the 3'UTR of ADRA2A, (2) the amount of repression is greater when the minor (risk) allele is present, (3) miR-34a in the IMR-32 adrenergic neuroblastoma cell line affects ADRA2A expression, (4) miR-34a and ADRA2A are expressed in tissues known to play a role in pain and stress, (5) following forced swim stress exposure, rat peripheral nerve tissue expression changes are consistent with miR-34a regulation of ADRA2A. Together, these results suggest that ADRA2A rs3750625 contributes to poststress musculoskeletal pain severity by modulating miR-34a regulation.

  13. [Hemodynamic types of hypertensive disease according to echocardiographic data].

    PubMed

    Zamotaev, I P; Dechko, E P

    1978-11-01

    Central hemodynamics was studied by means of echocardiography in 7 patients suffering from neurocirculatory dystonia with a high cardiac index but normal arterial pressure, and in 41 patients with essential hypertension prior to, and after treatment. Two groups of patients suffering from essential hypertension were distinguished: with a hyperkinetic type of circulation and with a normal cardiac index. In the first group there was a statistically significant increase in the stroke index and the index of diastolic left ventricular diameter with a normal ejection fraction. The increase in the cardiac index in the hyperkinetic type of essential hypertension is caused by an increase in the stroke output according to the Frank--Starling law. The authors believe that the increase in peripheral resistance is the principal pathogenetic mechanism of hypertension with any level of the minute volume.

  14. Hemodynamic changes in post-suspension rats during gradual hemorrhage

    NASA Astrophysics Data System (ADS)

    Vinogradova, O. L.; Borovik, A. S.; Tsvirkoun, D. V.; Tarasova, O. S.

    2005-08-01

    In urethane-anasthetized rats the effects of 2-week tail suspension upon the hemodynamic changes during simulated orthostatism and during loss of blood were studied. Baseline values of mean arterial pressure (MAP) and pulse interval (PI) did not differ in cage control (C) and post-suspension rats (TS). In both groups 45o head-up tilt resulted in prominent decline of MAP. In C group this effect was followed by the compensatory phase, which was virtually lost in TS group. No significant postural changes of PI were observed. Gradual hemorrhage (30% blood loss during 30 min) resulted in similar MAP drop in C and TS (up to 40% of baseline level). Along with that, PI increase was less prominent in TS (25%) compared to C (60%) indicating higher resistance of the heart to hypovolemia after suspension.

  15. Portal hypertension in vinyl chloride monomer workers. A hemodynamic study.

    PubMed

    Blendis, L M; Smith, P M; Lawrie, B W; Stephens, M R; Evans, W D

    1978-08-01

    Hemodynamic studies were performed in 5 vinyl chloride monomer workers in whom splenomegaly or thrombocytopenia was detected during a screening program at major chemical plant. Three patients had portal hypertension and collateral venous circulations, with intrasplenic pressures between 20 and 29 mm Hg and normal wedged hepatic venous pressures, but the gradient between the wedged and free hepatic vein pressures was also increased. Splenic blood flows were increased in both hypertensive and normotensive patients. There was no correlation between the splenic blood flow and the portal pressure or the presence of portal fibrosis. The portal hypertension associated with vinyl chloride exposure is mainly presinusoidal in type, and may be attributed to an abnormality of the portal vein radicles, or hepatic sinusoids.

  16. 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

  17. Vascular development and hemodynamic force in the mouse yolk sac

    PubMed Central

    Garcia, Monica D.; Larina, Irina V.

    2014-01-01

    Vascular remodeling of the mouse embryonic yolk sac is a highly dynamic process dependent on multiple genetic signaling pathways as well as biomechanical factors regulating proliferation, differentiation, migration, cell-cell, and cell-matrix interactions. During this early developmental window, the initial primitive vascular network of the yolk sac undergoes a dynamic remodeling process concurrent with the onset of blood flow, in which endothelial cells establish a branched, hierarchical structure of large vessels and smaller capillary beds. In this review, we will describe the molecular and biomechanical regulators which guide vascular remodeling in the mouse embryonic yolk sac, as well as live imaging methods for characterizing endothelial cell and hemodynamic function in cultured embryos. PMID:25191274

  18. 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.

  19. Pros and Cons of Using the Informed Basis Set to Account for Hemodynamic Response Variability with Developmental Data.

    PubMed

    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.

  20. 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

  1. Comparison of Remifentanil and Fentanyl Regarding Hemodynamic Changes Due to Endotracheal Intubation in Preeclamptic Parturient Candidate for Cesarean Delivery

    PubMed Central

    Pournajafian, Alireza; Rokhtabnak, Faranak; Kholdbarin, Alireza; Ghodrati, Mohammadreza; Ghavam, Siamak

    2012-01-01

    Background Intravenous opioids are administered to prevent and control hemodynamic changes due to endotracheal intubation. Except for special cases such as preeclampsia, these drugs are not recommended for parturants candidate for cesarean section because of the respiratory depression caused in the newborn. Objectives According to rapid metabolism of remifentanil, the current study aimed to compare hemodynamic changes in preeclamptic parturants who received remifentanil and fentanyl for cesarean section under general anesthesia. Patients and Methods This single blind randomized clinical trial was performed on preeclamptic pregnant women candidate for cesarean section under general anesthesia. They were divided into two groups. In the first group 0.05 μg/kg/min remifentanil was infused for 3 minutes before induction of anesthesia and in the second group 1ml (50 μg) fentanyl was injected before induction. Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) before and after intubation and also Apgar index were measured and compared between the two groups. Results All hemodynamic variables increased after intubation in the fentanyl group (pSBP = 0.146, pDBP = 0.019, pHR < 0.001). Additionally, decrease in SBP (P = 0.018) and DBP (P = 0.955) and mild increase in HR (P = 0.069) after intubation in the remifentanil group was observed. No significant difference was found between Apgar indexes of the two groups (P = 0.771). Conclusions It can be postulated that remifentanil can be used in partituents candidate for cesarean delivery under general anesthesia to prevent severe increase in blood pressure and heart rate during tracheal intubation without adverse effects on newborn. PMID:24223345

  2. Pulmonary arterial hypertension in Saudi Arabia: Patients' clinical and physiological characteristics and hemodynamic parameters. A single center experience

    PubMed Central

    Idrees, MM; Al-Najashi, K; Khan, A; Al-Dammas, S; Al-Awwad, H; Batubara, E; Al Otai, A; Abdulhameed, J; Fayed, A; Kashour, T

    2014-01-01

    AIMS: The main objective of this study is to describe patients' clinical characteristics and physiological and hemodynamic parameters at the time of diagnosis in a pulmonary hypertension center in Saudi Arabia. MATERIALS AND METHODS: This study reports the results from a single pulmonary hypertension specialized center in Riyadh, Saudi Arabia, namely Prince Sultan Medical Military City/Cardiac Center (PSMMC & CC). Both newly diagnosed (incidence) and referred (prevalence) cases of pulmonary arterial hypertension are included. All characteristics, including clinical, physiological, and hemodynamic parameters at the time of diagnosis are described. RESULTS: A total of 107 patients were identified as having pulmonary arterial hypertension as diagnosed by right heart catheterization. The mean age at diagnosis was 36 (± 9) years, and there was a female preponderance of 62.6%. The mean duration between symptom onset and diagnosis was 27.8 (± 9.0) months. At the time of enrollment, 56.1% of patients were in functional class III and 16.8% were in functional class IV. Fifty five patients (51.4%) were diagnosed as idiopathic pulmonary arterial hypertension, 29 patients (27.1%) as congenital heart disease associated with pulmonary arterial hypertension, 16 patients (15.0%) as connective tissue diseases associated with pulmonary arterial hypertension, 4 patients (3.7%) as heritable pulmonary arterial hypertension, and 3 patients (2.8%) as portopulmonary hypertension. CONCLUSION: This data highlights the current situation of pulmonary arterial hypertension in Saudi Arabia. Our patients are much younger than patients described in other international registries but still detected as late in the course of the disease. A majority of patients displays severe functional and hemodynamic compromise. PMID:25276239

  3. Effects of cardiac motion on right coronary artery hemodynamics.

    PubMed

    Zeng, Dehong; Ding, Zhaohua; Friedman, Morton H; Ethier, C Ross

    2003-04-01

    The purpose of this work was to investigate the effects of physiologically realistic cardiac-induced motion on hemodynamics in human right coronary arteries. The blood flow patterns were numerically simulated in a modeled right coronary artery (RCA) having a uniform circular cross section of 2.48 mm diam. Arterial motion was specified based on biplane cineangiograms, and incorporated physiologically realistic bending and torsion. Simulations were carried out with steady and pulsatile inflow conditions (mean ReD=233, alpha=1.82) in both fixed and moving RCA models, to evaluate the relative importance of RCA motion, flow pulsation, and the interaction between motion and flow pulsation. RCA motion with a steady inlet flow rate caused variations in wall shear stress (WSS) magnitude up to 150% of the inlet Poiseuille value. There was significant spatial variability in the magnitude of this motion-induced WSS variation. However, the time-averaged WSS distribution was similar to that predicted in a static model representing the time-averaged geometry. Furthermore, the effects of flow pulsatility dominated RCA motion-induced effects; specifically, there were only modest differences in the WSS history between simulations conducted in fixed and moving RCA models with pulsatile inflow. RCA motion has little effect on time-averaged WSS patterns. It has a larger effect on the temporal variation of WSS, but even this effect is overshadowed by the variations in WSS due to flow pulsation. The hemodynamic effects of RCA motion can, therefore, be ignored as a first approximation in modeling studies.

  4. 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.

  5. Effect of Sildenafil on Neuropathic Pain and Hemodynamics in Rats

    PubMed Central

    Huang, Lan Ji; Choi, Jeong Il; Kim, Woong Mo; Lee, Hyung Gon; Kim, Yeo Ok

    2010-01-01

    Purpose The inhibition of phosphodiesterase 5 produces an antinociception through the increase of cyclic guanosine monophosphate (cGMP), and increasing cGMP levels enhance the release of γ-aminobutyric acid (GABA). Furthermore, this phosphodiesterase 5 plays a pivotal role in the regulation of the vasodilatation associated to cGMP. In this work, we examined the contribution of GABA receptors to the effect of sildenafil, a phosphodiesterase 5 inhibitor, in a neuropathic pain rat, and assessed the hemodynamic effect of sildenafil in normal rats. Materials and Methods Neuropathic pain was induced by ligation of L5/6 spinal nerves in Sprague-Dawley male rats. After observing the effect of intravenous sildenafil on neuropathic pain, GABAA receptor antagonist (bicuculline) and GABAB receptor antagonist (saclofen) were administered prior to delivery of sildenafil to determine the role of GABA receptors in the activity of sildenafil. For hemodynamic measurements, catheters were inserted into the tail artery. Mean arterial pressure (MAP) and heart rate (HR) were measured over 60 min following administration of sildenafil. Results Intravenous sildenafil dose-dependently increased the withdrawal threshold to the von Frey filament application in the ligated paw. Intravenous bicuculline and saclofen reversed the antinociception of sildenafil. Intravenous sildenafil increased the magnitude of MAP reduction at the maximal dosage, but it did not affect HR response. Conclusion These results suggest that sildenafil is active in causing neuropathic pain. Both GABAA and GABAB receptors are involved in the antinociceptive effect of sildenafil. Additionally, intravenous sildenafil reduces MAP without affecting HR. PMID:20046518

  6. 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

  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. Investigation of cerebral hemodynamics and collateralization in asymptomatic carotid stenoses.

    PubMed

    AlMuhanna, Khalid; Zhao, Limin; Kowalewski, Gregory; Beach, Kirk W; Lal, Brajesh K; Sikdar, Siddhartha

    2012-01-01

    Stroke is the second leading cause of death in the world, and one of the major causes of disability. Approximately 30% of ischemic strokes are due to plaque rupture in the carotid arteries. The most popular diagnostic method uses Doppler ultrasound to find the percent stenosis. However, other factors, such as the hemodynamics around the plaque may play a larger role in identifying the risk of plaque rupture. It has been shown previously in simulations that non-collateral flow in the circle of Willis (COW) could cause an increase of the intraluminal velocity around carotid plaque. This added strain may increase the vulnerability of the plaque to rupture. We investigated asymmetries in flow waveforms in the middle cerebral artery (MCA) in asymptomatic patients with carotid artery stenosis. We compared clinical results of velocity waveforms in the MCA, acquired using transcranial Doppler (TCD), with a simple linear simulation model of the intra- and extracranial arterial network to investigate the relationship between contralateral and ipsilateral flow profiles in the MCA for patients with asymptomatic carotid stenosis. In 17 out of 23 patients we found waveforms consistent with those predicted for a collateralized COW, with minimal differences in delay, velocity magnitude and resistivity index. In 6 cases, some unexpected findings were noted, such as large delays for 2 patients ≤ 50% stenosis, and a large velocity difference with low delay for 4 patients. More studies are needed to elucidate the role of incomplete intracranial collateralization on the hemodynamics around carotid plaque and to use imaging of the COW to corroborate our results.

  9. 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

  10. Leonardo da Vinci and the first hemodynamic observations.

    PubMed

    Martins e Silva, J

    2008-02-01

    Leonardo da Vinci was a genius whose accomplishments and ideas come down to us today, five centuries later, with the freshness of innovation and the fascination of discovery. This brief review begins with a summary of Leonardo's life and a description of the most important works of art that he bequeathed us, and then concentrates on his last great challenge. There was a point at which Leonardo's passion for art gave way to the study of human anatomy, not only to improve his drawing but to go beyond what had been simply a representation of form to understand the underlying functioning. Among his many interests, we focus on his study of the heart and blood vessels, which he observed carefully in animals and human autopsies, and reproduced in drawings of great quality with annotations of astonishing acuteness. The experience that he had acquired from observing the flow of water in currents and around obstacles, and the conclusions that he drew concerning hydrodynamics, were central to his interpretation of the mechanisms of the heart and of blood flow, to which he devoted much of his time between 1508 and 1513. From these studies, immortalized in drawings of great clarity, come what are acknowledged to be the first hemodynamic records, in which Leonardo demonstrates the characteristics of blood flow in the aorta and great vessels and the importance of blood reflux and the formation of eddies in the sinus in aortic valve his assiduous and careful observations, and his subsequent deductions, Leonardo put forward detailed findings on hemodynamic questions that advanced technology has only recently enabled us to confirm.

  11. Fast Computation of Hemodynamic Sensitivity to Lumen Segmentation Uncertainty.

    PubMed

    Sankaran, Sethuraman; Grady, Leo; Taylor, Charles A

    2015-12-01

    Patient-specific blood flow modeling combining imaging data and computational fluid dynamics can aid in the assessment of coronary artery disease. Accurate coronary segmentation and realistic physiologic modeling of boundary conditions are important steps to ensure a high diagnostic performance. Segmentation of the coronary arteries can be constructed by a combination of automated algorithms with human review and editing. However, blood pressure and flow are not impacted equally by different local sections of the coronary artery tree. Focusing human review and editing towards regions that will most affect the subsequent simulations can significantly accelerate the review process. We define geometric sensitivity as the standard deviation in hemodynamics-derived metrics due to uncertainty in lumen segmentation. We develop a machine learning framework for estimating the geometric sensitivity in real time. Features used include geometric and clinical variables, and reduced-order models. We develop an anisotropic kernel regression method for assessment of lumen narrowing score, which is used as a feature in the machine learning algorithm. A multi-resolution sensitivity algorithm is introduced to hierarchically refine regions of high sensitivity so that we can quantify sensitivities to a desired spatial resolution. We show that the mean absolute error of the machine learning algorithm compared to 3D simulations is less than 0.01. We further demonstrate that sensitivity is not predicted simply by anatomic reduction but also encodes information about hemodynamics which in turn depends on downstream boundary conditions. This sensitivity approach can be extended to other systems such as cerebral flow, electro-mechanical simulations, etc.

  12. Correlation between electrical and hemodynamic responses during visual stimulation with graded contrasts

    NASA Astrophysics Data System (ADS)

    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.

  13. Effects of resuscitation with polymerized porcine hemoglobin (pPolyHb) on hemodynamic stability and oxygen delivery in a rat model of hemorrhagic shock.

    PubMed

    Wang, Li; Liu, Fang; Yan, Kunping; Pan, Wencan; Xu, Lijuan; Liu, Huifang; Yan, Chengbin; Chen, Chao; Zhu, Hongli

    2017-02-01

    The objective of this study was to evaluate the effects of polymerized porcine hemoglobin (pPolyHb) on hemodynamic stability and oxygen delivery in a rat model of hemorrhagic shock. Rats underwent controlled hemorrhage, resulting in the loss of 65% of their blood volume in 90 minutes. The results showed that pPolyHb was superior to hetastarch and saline, and similar to whole blood, in restoring hemodynamic stability and reversing anaerobic metabolism caused by hemorrhage. Furthermore, pPolyHb improved oxygen supply and increased blood oxygen content. These data suggest that pPolyHb can be effective in improving tissue perfusion under conditions of severe hemorrhagic shock.

  14. Establishment of the intracranial hemodynamic model based on contrast medium and clinical applications

    PubMed Central

    Cheng, Yaoer; He, Wen

    2016-01-01

    Abstract Ischemic cerebrovascular diseases are one of the most common vascular diseases in aged people and CT perfusion (CTP) is a very popular tool to detect the ischemic changes in brain vascular. The present study aims to establish a novel intracranial hemodynamic model to simulate anterior cerebral artery blood flow, and compare the actual and simulated hemodynamic parameters of healthy people and patients with carotid stenosis or occlusion. A mathematical model of the intracranial hemodynamic was generated using MATLAB software, and data from patients with or without infarct disease (57 and 44 cases, respectively) were retrospectively collected to test the new model. The actual time-density curve (TDC) of anterior cerebral artery was obtained from the original intracranial CTP data, and simulated TDC was calculated from our intracranial hemodynamic model. All model parameters were adjusted according to patients’ sex, height, and weight. Time to peak enhancement (TTP), maximum enhancement (ME), and mean transit time (MTT) were selected to evaluate the status of hemodynamics. In healthy people, there were no significant differences of TTP and ME between actual and simulated curves. For patients with infarct symptoms, ME was significantly decreased in actual data compared with simulated curve, while there was no obvious difference of TTP between actual and simulated data. Moreover, MTT was delayed in infarct patients compared with healthy people. Our group generated a computer-based, physiologic model to simulate intracranial hemodynamics. The model successfully simulated anterior cerebral artery hemodynamics in normal healthy people and showed noncompliant ME and MTT in infarct patients, reflecting their abnormal cerebral hemodynamic status. The digital model is reliable and may help optimize the protocol of contrast medium enhancement in intracranial CT, and provide a solid tool to study intracranial hemodynamics. PMID:27930555

  15. 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

  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. Echocardiographic and hemodynamic determinants of right coronary artery flow reserve and phasic flow pattern in advanced non-ischemic cardiomyopathy

    PubMed Central

    Graziosi, Pedro; Ianni, Barbara; Ribeiro, Expedito; Perin, Marco; Beck, Leonardo; Meneghetti, Claudio; Mady, Charles; Filho, Eulogio Martinez; Ramires, Jose AF

    2007-01-01

    Background In patients with advanced non-ischemic cardiomyopathy (NIC), right-sided cardiac disturbances has prognostic implications. Right coronary artery (RCA) flow pattern and flow reserve (CFR) are not well known in this setting. The purpose of this study was to assess, in human advanced NIC, the RCA phasic flow pattern and CFR, also under right-sided cardiac disturbances, and compare with left coronary circulation. As well as to investigate any correlation between the cardiac structural, mechanical and hemodynamic parameters with RCA phasic flow pattern or CFR. Methods Twenty four patients with dilated severe NIC were evaluated non-invasively, even by echocardiography, and also by cardiac catheterization, inclusive with Swan-Ganz catheter. Intracoronary Doppler (Flowire) data was obtained in RCA and left anterior descendent coronary artery (LAD) before and after adenosine. Resting RCA phasic pattern (diastolic/systolic) was compared between subgroups with and without pulmonary hypertension, and with and without right ventricular (RV) dysfunction; and also with LAD. RCA-CFR was compared with LAD, as well as in those subgroups. Pearson's correlation analysis was accomplished among echocardiographic (including LV fractional shortening, mass index, end systolic wall stress) more hemodynamic parameters with RCA phasic flow pattern or RCA-CFR. Results LV fractional shortening and end diastolic diameter were 15.3 ± 3.5 % and 69.4 ± 12.2 mm. Resting RCA phasic pattern had no difference comparing subgroups with vs. without pulmonary hypertension (1.45 vs. 1.29, p = NS) either with vs. without RV dysfunction (1.47 vs. 1.23, p = NS); RCA vs. LAD was 1.35 vs. 2.85 (p < 0.001). It had no significant correlation among any cardiac mechanical or hemodynamic parameter with RCA-CFR or RCA flow pattern. RCA-CFR had no difference compared with LAD (3.38 vs. 3.34, p = NS), as well as in pulmonary hypertension (3.09 vs. 3.10, p = NS) either in RV dysfunction (3.06 vs. 3.22, p

  18. Diagnosis and treatment guidelines for aberrant portal hemodynamics: The Aberrant Portal Hemodynamics Study Group supported by the Ministry of Health, Labor and Welfare of Japan.

    PubMed

    2017-01-06

    Idiopathic portal hypertension (IPH), causing aberrant portal hemodynamics, is a disease with an as yet unidentified cause and no established treatment protocol. The Japanese research group on IPH in Japan was set up in 1975 by the Ministry of Health, Labor and Welfare. Extrahepatic portal obstruction and Budd-Chiari syndrome (BCS) have since been added to the group's research subjects. The aims of the research group are to accurately evaluate the current status of the three diseases in Japan, elucidate their etiology and pathogenesis, and develop new treatments. Due to the long-term efforts of the Japanese research group, aberrant portal hemodynamics has been investigated in a variety of aspects, from epidemiological and pathological studies to molecular biology analyses. As a result, it has been shown that there are abnormal genes in the liver, specific for IPH. In addition, pathological findings of BCS were internationally compared and the difference in findings between Japan and Europe (or North America) has been clarified. Furthermore, it was found that complication rates of hepatocellular carcinoma in BCS were higher in Japan. Based on the research, "Diagnosis and treatment of aberrant portal hemodynamics (2001)", including diagnostic criteria for aberrant portal hemodynamics, was published in 2001. In 2013, it was revised to "Diagnosis and treatment guidelines for aberrant portal hemodynamics (2013)" after the incorporation of diagnosis and treatment in accordance with its current status.

  19. [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.

  20. Assessment of turbulent viscous stress using ICOSA 4D Flow MRI for prediction of hemodynamic blood damage

    PubMed Central

    Ha, Hojin; Lantz, Jonas; Haraldsson, Henrik; Casas, Belen; Ziegler, Magnus; Karlsson, Matts; Saloner, David; Dyverfeldt, Petter; Ebbers, Tino

    2016-01-01

    Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size. PLVS and PRSS were also overestimated by about 1.2 and 4.6 times at medium signal to noise ratio (SNR) = 20. In contrast, the square sum of the turbulent viscous shear stress (TVSS), which is used for blood damage index (BDI) estimation, was not severely affected by SNR and voxel size. The square sum of TVSS and the BDI at SNR >20 were underestimated by less than 1% and 10%, respectively. In conclusion, this study demonstrated the feasibility of 4D Flow MRI based quantification of TVSS and BDI which are closely linked to blood damage. PMID:28004789

  1. Assessment of turbulent viscous stress using ICOSA 4D Flow MRI for prediction of hemodynamic blood damage

    NASA Astrophysics Data System (ADS)

    Ha, Hojin; Lantz, Jonas; Haraldsson, Henrik; Casas, Belen; Ziegler, Magnus; Karlsson, Matts; Saloner, David; Dyverfeldt, Petter; Ebbers, Tino

    2016-12-01

    Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size. PLVS and PRSS were also overestimated by about 1.2 and 4.6 times at medium signal to noise ratio (SNR) = 20. In contrast, the square sum of the turbulent viscous shear stress (TVSS), which is used for blood damage index (BDI) estimation, was not severely affected by SNR and voxel size. The square sum of TVSS and the BDI at SNR >20 were underestimated by less than 1% and 10%, respectively. In conclusion, this study demonstrated the feasibility of 4D Flow MRI based quantification of TVSS and BDI which are closely linked to blood damage.

  2. 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.

  3. Assessment of turbulent viscous stress using ICOSA 4D Flow MRI for prediction of hemodynamic blood damage.

    PubMed

    Ha, Hojin; Lantz, Jonas; Haraldsson, Henrik; Casas, Belen; Ziegler, Magnus; Karlsson, Matts; Saloner, David; Dyverfeldt, Petter; Ebbers, Tino

    2016-12-22

    Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size. PLVS and PRSS were also overestimated by about 1.2 and 4.6 times at medium signal to noise ratio (SNR) = 20. In contrast, the square sum of the turbulent viscous shear stress (TVSS), which is used for blood damage index (BDI) estimation, was not severely affected by SNR and voxel size. The square sum of TVSS and the BDI at SNR >20 were underestimated by less than 1% and 10%, respectively. In conclusion, this study demonstrated the feasibility of 4D Flow MRI based quantification of TVSS and BDI which are closely linked to blood damage.

  4. Axial flow pump treatment during myocardial depression in calves: an invasive hemodynamic and echocardiographic tissue Doppler study.

    PubMed

    Hubbert, Laila; Peterzén, Bengt; Traff, Stefan; Janerot-Sjoberg, Birgitta; Ahn, Henrik

    2008-01-01

    The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.

  5. 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

  6. Resting hemodynamics after total versus standard orthotopic heart transplantation.

    PubMed

    Aleksic, I; Czer, L S; Freimark, D; Takkenberg, J J; Dalichau, H; Valenza, M; Blanche, C; Queral, C A; Nessim, S; Trento, A

    1996-08-01

    Total orthotopic heart transplantation (TOHT) requires longer surgery than standard orthotopic heart transplantation (SOHT), but offers normal anatomy and synchronous atrial contraction. We endeavored to test whether TOHT improves resting hemodynamics. We analyzed 60 patients with SOHT and 66 with TOHT transplanted between 12/89 and 7/94. Age, preoperative NYHA class, ejection fraction, and donor characteristics were similar. After applying exclusion criteria at 2 weeks postoperatively, 53 SOHT and 58 TOHT patients were accepted for further study. Right-heart hemodynamics were examined at 2 weeks and 6 months posttransplant. Despite a longer ischemic time (161 +/- 36 vs. 142 +/- 37 min, p = 0.004), cardiac output and index were higher in the TOHT group at 2 weeks (6.1 +/- 1.4 vs. 5.4 +/- 1.0 L/min, TOHT vs. SOHT, p = 0.01; and 3.3 +/- 0.7 vs. 2.9 +/- 0.6 L/min/m2, p = 0.005) but similar at 6 months (5.9 +/- 1.2 vs. 5.6 +/- 1.4 L/min; and 3.0 +/- 0.6 vs. 2.9 +/- 0.7 L/min/m2). Right-atrial pressure was lower with TOHT at both time points (7 +/- 4 vs. 9 +/- 4 mmHg, p = 0.02: and 5 +/- 2 vs. 7 +/- 3, p = 0.0006). Wedge pressure was similar at 2 weeks (12 +/- 5 vs. 13 +/- 5, p = 0.045). Heart rate (bpm) was higher at both time points with TOHT (84 +/- 10 vs. 75 +/- 12, p = 0.0003: and 90 +/- 12 vs. 82 +/- 9, p = 0.0006). Pulmonary vascular resistance was similar at both time points. Despite a longer ischemic time, total orthotopic heart transplantation does not impair postoperative cardiac function. There is an early improvement in cardiac output, a sustained higher heart rate reflecting preservation of donor sinus node function, and a lower right-atrial pressure.

  7. Renal nerve ultrastructural alterations in short term and long term experimental diabetes

    PubMed Central

    2014-01-01

    Background Despite the evidence that renal hemodynamics is impaired in experimental diabetes, associated with glomeruli structural alterations, renal nerves were not yet investigated in experimental models of diabetes and the contribution of nerve alterations to the diabetic nephropathy remains to be investigated. We aimed to determine if ultrastructural morphometric parameters of the renal nerves are affected by short term and/or long term experimental diabetes and if insulin treatment reverses these alterations. Left renal nerves were evaluated 15 days or 12 weeks (N = 10 in each group) after induction of diabetes, with a single injection of streptozotocin (STZ). Control rats (N = 10 in each group) were injected with vehicle (citrate buffer). Treated animals (N = 10 in each group) received a single subcutaneous injection of insulin on a daily basis. Arterial pressure, together with the renal nerves activity, was recorded 15 days (short-term) or 12 weeks (long-term) after STZ injection. After the recordings, the renal nerves were dissected, prepared for light and transmission electron microscopy, and fascicle and fibers morphometry were carried out with computer software. Results The major diabetic alteration on the renal nerves was a small myelinated fibers loss since their number was smaller on chronic diabetic animals, the average morphometric parameters of the myelinated fibers were larger on chronic diabetic animals and distribution histograms of fiber diameter was significantly shifted to the right on chronic diabetic animals. These alterations began early, after 15 days of diabetes induction, associated with a severe mitochondrial damage, and were not prevented by conventional insulin treatment. Conclusions The experimental diabetes, induced by a single intravenous injection of STZ, in adult male Wistar rats, caused small fiber loss in the renal nerves, probably due to the early mitochondrial damage. Conventional treatment with insulin was able

  8. ADIPONECTIN IN SEVERE PREECLAMPSIA

    PubMed Central

    Nien, Jyh Kae; Mazaki-Tovi, Shali; Romero, Roberto; Erez, Offer; Kusanovic, Juan Pedro; Gotsch, Francesca; Pineles, Beth L.; Gomez, Ricardo; Edwin, Samuel; Mazor, Moshe; Espinoza, Jimmy; Yoon, Bo Hyun; Hassan, Sonia S.

    2008-01-01

    Aims Adiponectin is an adipokine with insulin-sensitizing, anti-atherogenic, anti-inflammatory and angiogenic properties. The aims of this study were to determine whether maternal plasma adiponectin concentrations differ between patients with severe preeclampsia and those with normal pregnancies, and to explore the relationship between plasma adiponectin and the results of Doppler velocimetry of the uterine arteries. Methods This case-control study included two groups: (1) patients with severe preeclampsia (n=50) and (2) patients with normal pregnancies (n=150). Pulsed-wave and color Doppler ultrasound examination of the uterine arteries were performed. Plasma adiponectin concentrations were determined by ELISA. Non-parametric statistics were used for analysis. Results (1) Patients with severe preeclampsia had a higher median plasma concentration of adiponectin than that of normal pregnant women. (2) The median plasma adiponectin concentration did not differ between women with severe preeclampsia who had a high impedance to blood flow in the uterine arteries and those with normal impedance to blood flow. (3) Among patients with normal pregnancies, plasma adiponectin concentrations were negatively correlated with BMI in the first trimester and at sampling. Conclusions Women with severe preeclampsia have a higher median plasma concentration of adiponectin than that of normal pregnant women. This may reflect a compensatory feedback mechanism to the metabolically-altered, anti-angiogenic and pro-atherogenic state of severe preeclampsia. PMID:17919115

  9. Temporal analysis of fluctuations in cerebral hemodynamics revealed by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Toronov, Vlad; Fantini, Sergio; Franceschini, Maria-Angela; Filiaci, Mattia A.; Wolf, Martin; Gratton, Enrico

    2000-04-01

    We have non-invasively studied the motor cortex hemodynamics in human subjects under rest and motor stimulation conditions using a multichannel near-IR tissue spectrometer. We obtained optical maps of oxy- and deoxy-hemoglobin concentration changes in terms of amplitudes of folding average, power spectrum and coherence at the stimulation repetition frequency, and the phase synchronization index. Under periodic motor stimulation conditions, we observed coherence and phase synchronization of the local hemodynamic changes with stimulation.

  10. [Cerebral hemodynamics in patients with neurosensory hearing loss before and after magnetotherapy].

    PubMed

    Morenko, V M; Enin, I P

    2001-01-01

    Magnetotherapy effects on cerebral hemodynamics were studied using rheoencephalography (REG). When the treatment results and changes in cerebral hemodynamics were compared it was evident that normalization or improvement of vascular status in vertebrobasilar and carotid territories registered at REG results in better hearing. This confirms the role of vascular factor in pathogenesis of neurosensory hypoacusis of different etiology and effectiveness of magnetotherapy in such patients.

  11. 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.

  12. 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.

  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. The Effect of Hemodynamic Remodeling on the Survival of Arterialized Venous Flaps

    PubMed Central

    Yan, Hede; Kolkin, Jon; Zhao, Bin; Li, Zhefeng; Jiang, Shichao; Wang, Wei; Xia, Zhen; Fan, Cunyi

    2013-01-01

    Objective To evaluate the effect of hemodynamic remodeling on the survival status of the arterialized venous flaps (AVFs) and investigate the mechanism of this procedure. Materials and Methods Two 7 x 9 cm skin flaps in each rabbit (n=36) were designed symmetrically in the abdomen. The thoracoepigastric pedicle and one femoral artery were used as vascular sources. Four groups were included: Composite skin grafts group and arterial perfusion group were designed in one rabbit; AVF group and hemodynamic remodeling group by ligation of the thoracoepigastric vein in the middle were outlined in another rabbit. Flap viability, status of vascular perfusion and microvasculature, levels of epidermal metabolite and water content in each group were assessed. Results Highly congested veins and simple trunk veins were found using angiography in the AVF group; while a fairly uniform staining and plenty of small vessels were observed in the hemodynamic remodeling group. The metabolite levels of the remodeling group are comparable with those in the arterial perfusion group. There was no statistically significant difference in the percentage of flap survival between the arterial perfusion group and hemodynamic remodeling group; however, significant difference was seen between the AVF group and the hemodynamic remodeling group. Conclusions Under the integrated perfusion mode, the AVFs are in an over-perfusion and non-physiological hemodynamic state, resulting in unreliability and unpredictability in flap survival; under the separated perfusion mode produced by remodeling, a physiological-like circulation will be created and therefore, better flap survival can be expected. PMID:24265782

  15. Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension.

    PubMed

    Brito, L C; Queiroz, A C C; Forjaz, C L M

    2014-08-01

    Due to differences in study populations and protocols, the hemodynamic determinants of post-aerobic exercise hypotension (PAEH) are controversial. This review analyzed the factors that might influence PAEH hemodynamic determinants, through a search on PubMed using the following key words: "postexercise" or "post-exercise" combined with "hypotension", "blood pressure", "cardiac output", and "peripheral vascular resistance", and "aerobic exercise" combined only with "blood pressure". Forty-seven studies were selected, and the following characteristics were analyzed: age, gender, training status, body mass index status, blood pressure status, exercise intensity, duration and mode (continuous or interval), time of day, and recovery position. Data analysis showed that 1) most postexercise hypotension cases are due to a reduction in systemic vascular resistance; 2) age, body mass index, and blood pressure status influence postexercise hemodynamics, favoring cardiac output decrease in elderly, overweight, and hypertensive subjects; 3) gender and training status do not have an isolated influence; 4) exercise duration, intensity, and mode also do not affect postexercise hemodynamics; 5) time of day might have an influence, but more data are needed; and 6) recovery in the supine position facilitates systemic vascular resistance decrease. In conclusion, many factors may influence postexercise hypotension hemodynamics, and future studies should directly address these specific influences because different combinations may explain the observed variability in postexercise hemodynamic studies.

  16. 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.

  17. Importance of hemodynamic forces as signals for exercise-induced changes in endothelial cell phenotype.

    PubMed

    Laughlin, M Harold; Newcomer, Sean C; Bender, Shawn B

    2008-03-01

    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.

  18. Computational assessment of the effects of the catheter type on particle-hemodynamics during liver radioembolization.

    PubMed

    Aramburu, Jorge; Antón, Raúl; Rivas, Alejandro; Ramos, Juan Carlos; Sangro, Bruno; Bilbao, José Ignacio

    2016-11-07

    Radioembolization, which consist of the implantation of radioactive microspheres via intra-arterially placed microcatheter, is a safe and effective treatment for liver cancer. Nevertheless, radioembolization-related complications and side effects may arise, which are an active area of ongoing research. The catheter design has been claimed as an option in reducing these complications. In this paper, the influence of catheter type and location are investigated. The study was undertaken by numerically simulating the particle-hemodynamics in a patient-specific hepatic artery during liver radioembolization. The parameters modified were cancer scenario (30% liver involvement in the right lobe, 'scenario A', and in both lobes, 'scenario B'), catheter type (standard end-hole microcatheter, SMC, and antireflux catheter, ARC), and the location of the tip in the proper hepatic artery (in the straight part, 'inlet', and near the bifurcation, 'bifurcation'). Comparing ARC with SMC, the maximum and average (over segments) absolute difference in the percentage of particles that reached each segment were 19.62% and 9.06% when injecting near the inlet for scenario A; 3.54% and 1.07% injecting near the bifurcation for scenario A; and 18.31% and 11.85% injecting near the inlet for scenario B. It seems, therefore, that the location of the catheter tip in the artery is crucial in terms of particle distribution. Moreover, even though the near-tip blood flow was altered due to the presence of a catheter, the particle distribution matched the flow split if the distance between the injection point and the first bifurcation encountered enabled the alignment of particles with blood flow.

  19. 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.

  20. 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

  1. 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

  2. Hemodynamic shear stress and the endothelium in cardiovascular pathophysiology

    PubMed Central

    Davies, Peter F

    2010-01-01

    SUMMARY Endothelium lining the cardiovascular system is highly sensitive to hemodynamic shear stresses that act at the vessel luminal surface in the direction of blood flow. Physiological variations of shear stress regulate acute changes in vascular diameter and when sustained induce slow, adaptive, structural-wall remodeling. Both processes are endothelium-dependent and are systemically and regionally compromised by hyperlipidemia, hypertension, diabetes and inflammatory disorders. Shear stress spans a range of spatiotemporal scales and contributes to regional and focal heterogeneity of endothelial gene expression, which is important in vascular pathology. Regions of flow disturbances near arterial branches, bifurcations and curvatures result in complex spatiotemporal shear stresses and their characteristics can predict atherosclerosis susceptibility. Changes in local artery geometry during atherogenesis further modify shear stress characteristics at the endothelium. Intravascular devices can also influence flow-mediated endothelial responses. Endothelial flow-induced responses include a cell-signaling repertoire, collectively known as mechanotransduction, that ranges from instantaneous ion fluxes and biochemical pathways to gene and protein expression. A spatially decentralized mechanism of endothelial mechanotransduction is dominant, in which deformation at the cell surface induced by shear stress is transmitted as cytoskeletal tension changes to sites that are mechanically coupled to the cytoskeleton. A single shear stress mechanotransducer is unlikely to exist; rather, mechanotransduction occurs at multiple subcellular locations. PMID:19029993

  3. Hemodynamics before and after bleb formation in cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan R.; Radaelli, Alessandro; Frangi, Alejandro; Putman, Christopher M.

    2007-03-01

    We investigate whether blebs in cerebral aneurysms form in regions of low or high wall shear stress (WSS), and how the intraaneurysmal hemodynamic pattern changes after bleb formation. Seven intracranial aneurysms harboring well defined blebs were selected from our database and subject-specific computational models were constructed from 3D rotational angiography. For each patient, a second anatomical model representing the aneurysm before bleb formation was constructed by smoothing out the bleb. Computational fluid dynamics simulations were performed under pulsatile flow conditions for both models of each aneurysm. In six of the seven aneurysms, the blebs formed in a region of elevated WSS associated to the inflow jet impaction zone. In one, the bleb formed in a region of low WSS associated to the outflow zone. In this case, the inflow jet maintained a fairly concentrated structure all the way to the outflow zone, while in the other six aneurysms it dispersed after impacting the aneurysm wall. In all aneurysms, once the blebs formed, new flow recirculation regions were formed inside the blebs and the blebs progressed to a state of low WSS. Assuming that blebs form due to a focally damaged arterial wall, these results seem to indicate that the localized injury of the vessel wall may be caused by elevated WSS associated with the inflow jet. However, the final shape of the aneurysm is probably also influenced by the peri-aneurysmal environment that can provide extra structural support via contact with structures such as bone or dura matter.

  4. Image based numerical simulation of hemodynamics in a intracranial aneurysm

    NASA Astrophysics Data System (ADS)

    Le, Trung; Ge, Liang; Sotiropoulos, Fotis; Kallmes, David; Cloft, Harry; Lewis, Debra; Dai, Daying; Ding, Yonghong; Kadirvel, Ramanathan

    2007-11-01

    Image-based numerical simulations of hemodynamics in a intracranial aneurysm are carried out. The numerical solver based on CURVIB (curvilinear grid/immersed boundary method) approach developed in Ge and Sotiropoulos, JCP 2007 is used to simulate the blood flow. A curvilinear grid system that gradually follows the curved geometry of artery wall and consists of approximately 5M grid nodes is constructed as the background grid system and the boundaries of the investigated artery and aneurysm are treated as immersed boundaries. The surface geometry of aneurysm wall is reconstructed from an angiography study of an aneurysm formed on the common carotid artery (CCA) of a rabbit and discretized with triangular meshes. At the inlet a physiological flow waveform is specified and direct numerical simulations are used to simulate the blood flow. Very rich vortical dynamics is observed within the aneurysm area, with a ring like vortex sheds from the proximal side of aneurysm, develops and impinge onto the distal side of the aneurysm as flow develops, and destructs into smaller vortices during later cardiac cycle. This work was supported in part by the University of Minnesota Supercomputing Institute.

  5. Clinical and hemodynamic effects of the new dilator drug molsidomine.

    PubMed

    Malcolm, A D

    1985-03-01

    The effects of a single 2 mg oral dose of molsidomine were assessed with treadmill multistage exercise testing in six men with stable angina. A double-blind, placebo-controlled protocol was used, with exercise to the point when anginal pain forced the patient to stop. Exercise was undertaken before and at 1/2, 1 1/2, 4, and 6 hours after drug administration. Molsidomine improved exercise performance, with the best antianginal effect at 1 1/2 hours after administration, when the mean times to limiting angina were approximately 6 3/4 minutes with placebo and 11 1/2 minutes with molsidomine (p less than 0.05). The corresponding energy expenditures were 33.8 and 77.6 mets, an increase of 130% with the active drug. Intra-arterial blood pressure recording verified that molsidomine had a vasodilator hemodynamic profile, and the immediate postexercise rate-pressure product 1 1/2 hours after molsidomine treatment was 232 mm Hg/min X 10(-2), compared with 183 mm Hg/min X 10(-2) after administration of placebo (NS). Side effects of molsidomine were limited to headache in two patients.

  6. [Hemodynamic sequelae following valve replacement in patients with aortic regurgitation].

    PubMed

    Onishi, S; Handa, S; Ikeda, F; Hosokawa, M; Yoshino, H; Ogawa, S; Nakamura, Y; Soma, Y; Inoue, T

    1989-06-01

    Serial echocardiographic analyses of the left ventricle (LV) were performed in 61 patients with aortic regurgitation before, one-six months, and six years after aortic valve replacement (AVR). There was no significant difference in the preoperative hemodynamic and echocardiographic data between 54 survivors and six deceased patients. There was a linear correlation (r = 0.69) between LV end-diastolic volume (EDV) by cineangiography and LV end-diastolic dimension (LVDd) by echocardiography. In patients with LV end-diastolic pressure (EDP) less than 12 mmHg, the LV was markedly dilated before surgery, and LVDd was not normalized until half a year after surgery in half the cases. In 20 patients with LVEDP greater than 12 mmHg, LVDd was normalized in 17 patients up to half a year after surgery. In 11 patients with LV end-systolic dimension (LVDs) greater than 5.2 cm, LVDs was not normalized until six years post surgery in three patients. LVDd was improved six years after surgery in patients with LVDs less than 5.2 cm. Echocardiographically-determined LVDs less than 5.2 cm is recommended for preservation of LV function following aortic valve replacement.

  7. Effects of adenosine infusion into renal interstitium on renal hemodynamics

    SciTech Connect

    Pawlowska, D.; Granger, J.P.; Knox, F.G.

    1987-04-01

    This study was designed to investigate the hemodynamic effects of exogenous adenosine in the interstitium of the rat kidney. Adenosine or its analogues were infused into the renal interstitium by means of chronically implanted capsules. In fusion of adenosine decreased glomerular filtration rate (GFR) from 0.81 +/- 0.06 to 0.37 +/- 0.06 ml/min while having no effect on renal blood flow (RBF). The metabolically stable analogue, 2-chloradenosine (2-ClAdo), decreased GFR from 0.73 +/- 0.07 to 021 +/- 0.06 ml/min. Interstitial infusion of theophylline, an adenosine receptor antagonist, completely abolished the effects of adenosine and 2-ClAdo on GFR. The distribution of adenosine, when infused into the renal interstitium, was determined using radiolabeled 5'-(N-ethyl)-carboxamidoadenosine (NECA), a metabolically stable adenosine agonist. After continuous infusion, (/sup 3/H)NECA was distributed throughout the kidney. The effects of NECA to reduce GFR were similar to those of adenosine and 2-ClAdo. They conclude that increased levels of adenosine in the renal interstitium markedly decrease GFR without affecting RBF in steady-state conditions. The marked effects of adenosine agonists during their infusion into the renal interstitium and the complete blockade of these effects by theophylline suggest an extracellular action of adenosine.

  8. Ocular hemodynamic effects of nitrovasodilators in healthy subjects.

    PubMed

    Schmidl, D; Polska, E; Kiss, B; Sacu, S; Garhofer, G; Schmetterer, L

    2010-01-01

    Nitric oxide (NO) plays a key role in the regulation of ocular blood flow and may be an interesting therapeutic target in ocular ischemic disease. In the present study, we hypothesized that NO-releasing drugs may increase blood flow to the head of the optic nerve and also in the choroid. The study employed a randomized, placebo-controlled, double blind, four-way crossover design. On separate study days, 12 healthy subjects received infusions of nitroglycerin, isosorbide dinitrate, sodium nitroprusside, or placebo. All three study drugs reduced the mean arterial pressure (MAP) and ocular perfusion pressure (OPP) (P < 0.001). None of the administered drugs increased the ocular hemodynamic variables. By contrast, vascular resistance decreased dose dependently during administration of the study drugs (P < 0.001). These results indicate that systemic administration of NO-donor drugs is associated with a decrease in vascular resistance in the ocular vasculature. However, because these drugs also reduce blood pressure, they do not improve perfusion to the posterior eye pole.

  9. Posttraumatic shock in children: CT findings associated with hemodynamic instability.

    PubMed

    Sivit, C J; Taylor, G A; Bulas, D I; Kushner, D C; Potter, B M; Eichelberger, M R

    1992-03-01

    Twenty-seven of 1,018 children evaluated with contrast material-enhanced computed tomography (CT) after blunt trauma demonstrated a characteristic hypoperfusion complex. This complex was usually seen in young children (median age, 2 years). CT findings in all 27 patients included a dilated, fluid-filled bowel and abnormally intense enhancement of the bowel wall, mesentery, kidneys, aorta, and inferior vena cava. Twenty-four percent of all children with a Trauma Score of 10 or less and 20% with a Glasgow Coma Score of 6 or less had the hypoperfusion complex. All 27 patients had a normal blood pressure immediately before CT, but five (19%) became hypotensive within 10 minutes of intravenous contrast material administration. Twenty-three children (85%) died. Of 16 children who survived 24 hours, four (25%) developed renal insufficiency. The intense multiorgan enhancement pattern seen in the hypoperfusion complex indicates tenuous hemodynamic stability. Recognition that the constellation of CT findings is due to hypovolemic shock and not to injured viscera helps avoid unnecessary laparotomy.

  10. Renal Function and Hemodynamic Study in Obese Zucker Rats

    PubMed Central

    Park, Sung Kwang; Kang, Sung Kyew

    199