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Pulsatile flow

About: Pulsatile flow is a research topic. Over the lifetime, 6278 publications have been published within this topic receiving 149638 citations.


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TL;DR: Understanding the pulsatile arterial hemodynamics that elevate cardiovascular risk has led to the use of pharmacological therapies, which prevent arterial stiffness and reduce wave reflections, and improve cardiovascular morbidity and mortality.
Abstract: Arterial aging can be attributed to two different pathophysiological changes--increase in arterial stiffness and disturbed wave reflections The capacity of the aorta to absorb the force exerted by the left ventricular ejection and dampen pulsatile flow becomes diminished with advancing age, owing to the progressive hardening of the arterial wall These changes contribute to increase blood pressure, mainly systolic blood pressure and pulse pressure, which can trigger cardiovascular events Understanding the pulsatile arterial hemodynamics that elevate cardiovascular risk has led to the use of pharmacological therapies, which prevent arterial stiffness and reduce wave reflections, and improve cardiovascular morbidity and mortality Antifibrotic agents, such as those that block the renin-angiotensin-aldosterone pathway, are often given in association with diuretics, calcium-channel blockers, or both, but not with standard beta-blockers Consistent reductions in cardiovascular outcomes obtained using these agents can be predicted through noninvasive measurements of central systolic blood pressure and pulse pressure

142 citations

Journal ArticleDOI
TL;DR: Steady flow results that model the inspiratory phase at Reynolds numbers of 518, 1036 and 2089, corresponding to Dean numbers of 98, 196 and 395, show that in the bifurcation plane velocity profiles in the daughter branches are skewed toward the inner wall.
Abstract: Flow in a bifurcating tube system typifying a major bronchial bifurcation is studied experimentally with a two color, two velocity component laser Doppler anemometer. The flow loop is composed of a pumping station, flow stratifiers and a constant head pressure tank; it can accommodate steady, pulsatile or oscillatory flow. The test section is a symmetric bifurcation of constant cross sectional area and has a branching angle of 70 deg. The test section is a cast of clear silicon rubber in a plexiglass mold that was milled on a numerically controlled milling machine. The flow division ratio from the parent to daughter branches is about unity. Steady flow results that model the inspiratory phase at Reynolds numbers of 518, 1036 and 2089, corresponding to Dean numbers of 98, 196 and 395, show that in the bifurcation plane velocity profiles in the daughter branches are skewed toward the inner wall. In the transverse plane, "m" shaped velocity profiles are found with low velocity at the center. Secondary flow patterns, which are responsible for such phenomena, are first observed at the axial position where the flow begins to turn. Flow separation was not observed at any point in the bifurcation.

142 citations

Journal ArticleDOI
TL;DR: In patients with primary pulmonary hypertension, the stroke volume response to exercise was strongly related to rest levels of pulmonary artery diastolic pressure, pulmonary vascular resistance and the reflection factor, whereas no such relation was found in the control subjects.

142 citations

Journal ArticleDOI
TL;DR: The stress phase angle (SPA), which characterizes the dynamics of the mechanical force pattern applied to the endothelial cell layer, shows that CS and WSS are more out of phase in the coronaries than in any other region of the circulation, suggesting that in addition to WSS, SPA may play a role in localization of coronary atherosclerosis.
Abstract: The endothelial cells (ECs) lining a blood vessel wall are exposed to both the wall shear stress (WSS) of blood flow and the circumferential strain (CS) of pulsing artery wall motion. These two forces and their interaction are believed to play a role in determining remodeling of the vessel wall and development of arterial disease (atherosclerosis). This study focused on the WSS and CS dynamic behavior in a compliant model of a coronary artery taking into account the curvature of the bending artery and physiological radial wall motion. A three-dimensional finite element model with transient flow and moving boundaries was set up to simulate pulsatile flow with physiological pressure and flow wave forms characteristic of the coronary arteries. The characteristic coronary artery curvature and flow conditions applied to the simulation were: aspect ratio (lambda) = 10, diameter variation (DV) = 6 percent, mean Reynolds number (Re) = 150, and unsteadiness parameter (alpha) = 3. The results show that mean WSS is about 50 percent lower on the inside wall than the outside wall while WSS oscillation is stronger on the inside wall. The stress phase angle (SPA) between CS and WSS, which characterizes the dynamics of the mechanical force pattern applied to the endothelial cell layer, shows that CS and WSS are more out of phase in the coronaries than in any other region of the circulation (-220 deg on the outside wall, -250 deg on the inside wall). This suggests that in addition to WSS, SPA may play a role in localization of coronary atherosclerosis.

142 citations

Journal ArticleDOI
TL;DR: The findings suggest that the cell junction remodeling induced by different flow patterns may result from a redistribution of VE-cadherin within the cell membrane.
Abstract: Atherosclerosis occurs preferentially at vascular curvature and branch sites where the vessel walls are exposed to fluctuating shear stress and have high endothelial permeability. Endothelial permeability is modulated by intercellular adhesion molecules such as VE-cadherin. This study was designed to elucidate the effects of different flow patterns on the localization and expression of VE-cadherin in endothelial cells (ECs) both in vivo and in vitro. VE-cadherin staining at EC borders was much stronger in the descending thoracic aorta and abdominal aorta, where the pulsatile flow has a strong net forward component than in the aortic arch and the poststenotic dilatation site beyond an experimental constriction, where the flow near the wall is complex and reciprocating with little net flow. With the use of flow chambers the effects of pulsatile flow (12 +/- 4 dyn/cm2 at 1 Hz) and reciprocating flow (0.5 +/- 4 dyn/cm2 at 1 Hz) on VE-cadherin organization in endothelial monolayers were studied in vitro. VE-cadherin staining was continuous along cell borders in static controls. Following 6 h of either pulsatile or reciprocating flow, the VE-cadherin staining at cell borders became intermittent. When the pulsatile flow was extended to 24, 48 or 72 h the staining around the cell borders became continuous again, but the staining was still intermittent when the reciprocating flow was similarly extended. Exposure to pulsatile or reciprocating flow for 6 and 24 h neither change the expression level of VE-cadherin nor its distribution between membrane and cytosol fractions as determined by Western blot and compared with static controls. These findings suggest that the cell junction remodeling induced by different flow patterns may result from a redistribution of VE-cadherin within the cell membrane. Both the in vivo and in vitro data indicate that pulsatile and reciprocating flow patterns have different effects on cell junction remodeling. The lack of junction reorganization in regions of reciprocating flow in vivo and in vitro may provide a mechanistic basis for the high permeability and the preferential localization of atherosclerosis in regions of the arterial stress with complex flow patterns and fluctuating shear stress.

142 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023274
2022641
2021170
2020181
2019171
2018189