Pulsatile flow

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

The fluid mechanics of the aortic valve

Abstract: The closure mechanism of the human aortic valve is investigated experimentally with a rigid-walled model placed in a pulsatile water-tunnel. It is shown that the valve is controlled by a fluid feed-back system incorporating a stagnation point at the downstream end of each sinus and a trapped vortex within it, and that threequarters of the valve's closure is accomplished during forward flow, requiring only very little reversed flow to seal it. The experiments are complemented by solutions of the inviscid-flow equations, based on a Hill spherical vortex model.

Phase-velocity cine magnetic resonance imaging measurement of pulsatile blood flow in children and young adults: in vitro and in vivo validation.

Abstract: Quantification of blood flow in vessels provides valuable information that aids management decisions in a variety of cardiac conditions. Current flow measurement techniques are often limited by accuracy, time resolution, convenience, or anatomic localization. This study examined the accuracy of a commercially available phase-velocity cine magnetic resonance imaging (PVC MRI) technique to quantify flow rate in a pulsatile flow phantom. In addition, the equivalence of PVC MRI measurements of pulmonary and systemic flow was evaluated in children and adults without any pathologic shunt. Using a pulsatile flow phantom, volume flow rates measured by PVC MRI were compared to those by a transit-time ultrasound flowmeter over a range of flow rates (1.25–3.5 L/min, 13 trials). Close agreement was found between these techniques (y= 1.02x− 0.02, r= 0.99, Bland–Altman bias =−0.045 L/min, 95% limits of agreement =−0.19–0.10 L/min). Twenty subjects (median age 12.8 years, range 0.7–49 years) with no pathologic shunt underwent PVC MRI measurement of blood flow in the main pulmonary artery (Qp) and the ascending aorta (Qs). Data processing time for each location was 20 minutes. The Qp/Qs ratio closely approximated unity (mean = 0.99, SD = 0.10, range 0.85–1.19). Interobserver agreement was excellent (Bland–Altman bias = 0.09 L/min, 95% limits of agreement = 0.15–0.33 L/min). PVC MRI is an accurate technique to quantify pulsatile blood flow at a specific location. It can be used to noninvasively calculate Qp and Qs under normal flow conditions.

A microscope-television system for studying flow velocity in human skin capillaries

Abstract: A noninvasive technique for studying blood flow dynamics in human skin capillaries is described A light microscope combined with a closed-circuit TV system was used to monitor and record capillary blood flow velocity on video tape Arterial pulsations were recorded plethysmographically and converted into video signals by modulating the position of a square, white area in the televised scene Twelve healthy subjects were studied The mean (+/- SD) resting capillary blood flow velocity was 065 +/- 03 mm/s at an average skin temperature of 304 +/- 23 degrees C Spontaneous fluctuations at a frequency of 6-10 cycles/min were observed in most subjects A well-pronounced flow pulsatile component could be demonstrated in all capillaries studied The technique can be used in clinical practice for studying the physiology and pathophysiology of cutaneous microcirculation in man It can be expected that the method may become an important diagnostic tool in diseases that involve disturbances of the microcirculation, such as diabetes, hypertension, and atherosclerosis