Topic
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: A summary of in vivo IOP-induced patterns of cyclic flow that can be used as part of a framework for interpretation of responses to cyclic stresses identified in the laboratory are provided.
100 citations
Patent•
01 Dec 1982
TL;DR: In this paper, a mechanism, such as a motor driving a pump, creates a pulsating fluid flow and a control for varying the pulsation frequency independently of the fluid pressure or rate of flow.
Abstract: A mechanism, such as a motor driving a pump, creates a pulsating fluid flow. There is a control for varying the pulsation frequency independently of the fluid pressure or rate of flow. Another control varies the pressure or rate of fluid flow independently of the frequency of pulsation. Separate pulsatile lavage, irrigation, and aspiration functions are provided. In another aspect, the mechanism for producing the pulsating flow includes a fluid driving means, such as a reciprocating pump, and there is a means for varying the length of stroke of the driving means.
99 citations
TL;DR: Plasma modified ePTFE vascular grafts enhanced the endothelial cell lining under constant and pulsatile flow conditions, revealing the presence of nitrogen-containing functional groups on the plasma modified graft surfaces, along with an increased surface hydrophilicity.
Abstract: We sought to examine whether surface modification of expanded polytetrafluoroethylene (ePTFE) vascular grafts might extend graft patency without modifying the graft structure. Amide and amine plasma (butylamine) were applied to graft surfaces using radio frequency glow discharge. Surface analyses by Fourier transform infrared spectroscopy-attenuated total reflectance, X-ray photoelectron spectroscopy, and dynamic contact angle measurements revealed the presence of nitrogen-containing functional groups on the plasma modified graft surfaces, along with an increased surface hydrophilicity. Bovine aortic endothelial cells were seeded on amide and amine plasma coated ePTFE vascular grafts and placed inside an artificial circulatory system under well-defined flow conditions. The seeded endothelial cells were exposed to either constant or pulsatile flow condition for 5 days. Their corresponding maximum wall shear stresses were 1 dyn/cm2 under constant flow and 65, 108, and 259 dyn/cm2 under various pulsatile flows. Plasma modified ePTFE vascular grafts enhanced the endothelial cell lining under constant and pulsatile flow conditions. Fluorescence nuclear staining, scanning electron microscopy, and histological staining indicated the formation of an endothelial cell monolayer on the plasma coated graft surfaces.
99 citations
TL;DR: Heart failure patients with continuous, nonpulsatile LVADs have marked sympathetic activation, which is likely due, at least in part, to baroreceptor unloading, and it is speculated that such chronic sympathetic activation may contribute to, or worsen end-organ diseases, and reduce the possibility of ventricular recovery.
Abstract: Background—Left ventricular assist devices (LVADs) are now widely accepted as an option for patients with advanced heart failure. First-generation devices were pulsatile, but they had poor longevity and durability. Newer generation devices are nonpulsatile and more durable, but remain associated with an increased risk of stroke and hypertension. Moreover, little is understood about the physiological effects of the chronic absence of pulsatile flow in humans. Methods and Results—We evaluated patients with pulsatile (n=6) and nonpulsatile (n=11) LVADs and healthy controls (n=9) during head-up tilt while measuring hemodynamics and muscle sympathetic nerve activity. Patients with nonpulsatile devices had markedly elevated supine and upright muscle sympathetic nerve activity (mean±SD, 43±15 supine and 60±21 bursts/min at 60° head-up tilt) compared with patients with pulsatile devices (24±7 and 35±8 bursts/min; P<0.01) and controls (11±6 and 31±6 bursts/min; P<0.01); however, muscle sympathetic nerve activity w...
99 citations
TL;DR: A mathematical model is developed here to explain the results obtained when pressure is applied to either covered or uncovered samples, and predicts the rate of exudation in both instances should be substantially identical for a period of time ∼0.2τ, where τ is the consolidation time.
99 citations