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: Hemodynamic alterations of magnitudes documented in this study assume clinical importance and the assumption that a solitary critical stenosis must exist before significant hemodynamic changes occur is no longer tenable.
Abstract: Diminished poststenotic pressure and flow accompanied experimental application of multiple subcritical arterial stenoses in series. Effects of additional stenoses, causing equivalent constrictions, were cumulative in a nonlinear fashion. Seven-hundred-twenty measurements were performed using 10 cm ileofemoral canine arterial segments in vitro and in vivo with pulsatile and nonpulsatile blood flow. Pressures and flow volumes utilized for testing were within normal physiologic ranges. Data analysis included correlations of experimental observations with predictions generated from a theoretic hydraulic model. Kinetic energy losses with multiple subcritical stenoses were associated with decreased pressure and flow. Poststenotic pressure decreased as much as 51% in some experiments. Diminutions in flow paralleled pressure changes. Measured pressure changes were nonlinear and followed mathematic predictions of appreciable but lesser effects of added stenoses. Hemodynamic alterations of magnitudes documented in this study assume clinical importance. The assumption that a solitary critical stenosis must exist before significant hemodynamic changes occur is no longer tenable.
68 citations
TL;DR: The finite element method is used to solve the time-dependent Navier-Stokes equations for pulsatile flow through a model of the human carotid bifurcation and the mathematical results show the zones of reversed flow during the pulse period and the paths of single blood particles in the flow field.
68 citations
TL;DR: Data demonstrate that pulsatile flow can significantly attentuate the vasopressin stress response to bypass and may partially explain the higher flow requirements and the decrease in Na+ excretion.
68 citations
TL;DR: Once-daily treatment with 0.005% latanoprost provides a significant and stable IOP reduction in the majority of NTG patients after short-term treatment, accompanied by a significant increase in POBF.
Abstract: The effect of once-daily latanoprost on intraocular pressure and pulsatile ocular blood flow in normal tension glaucoma
68 citations
TL;DR: PhS-OCT reveals pulse-induced motion of the TM that may provide insights into the biomechanics of the tissues involved in the regulation of IOP, and develops and applies a phase compensation algorithm to permit quantification of TM motion and relationships.
Abstract: Aqueous leaves the anterior chamber of eye by passing through the trabecular meshwork (TM), a tissue thought to be responsible for increased outflow resistance in glaucoma. Motion assessment could permit characterization of TM biomechanical properties necessary to maintain intra-ocular pressure (IOP) within a narrow homeostatic range. In this paper, we report the first in vivo identification of TM motion in humans. We use a phase-sensitive optical coherence tomography (PhS-OCT) system with sub-nanometer sensitivity to detect and image dynamic pulse-induced TM motion. To permit quantification of TM motion and relationships we develop and apply a phase compensation algorithm permitting removal of the otherwise evitable confounding effects of bulk motion. Twenty healthy human eyes from 10 subjects are imaged. The results permit visualization of pulsatile TM motion visualization by PhS-OCT; correlation with the digital/cardiac pulse is highly significant. The correlation permits assessment of the phase lag and time delay between TM motion and the cardiac pulse. In this study, we find that the digital pulse leads the pulsatile TM motion by a mean phase of 3.53 ± 0.48 rad and a mean time of 0.5 ± 0.14 s in the fundamental frequency. A significant linear relationship is present between the TM phase lag and the heart rate (p value < 0.05). The TM phase lag is also affected by age, the relationship not quite reaching significance in the current study. PhS-OCT reveals pulse-induced motion of the TM that may provide insights into the biomechanics of the tissues involved in the regulation of IOP.
68 citations