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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14 May 1997TL;DR: In this article, a synchronous, pulsatile angioplasty system utilizes a control apparatus which controls balloon inflation and deflation in a pulsatile fashion synchronized with the heartbeat of a patient.
Abstract: A synchronous, pulsatile angioplasty system utilizes a control apparatus which controls balloon inflation and deflation in a pulsatile fashion synchronized with the heartbeat of a patient. A heart monitor provides an input, a signal to the control apparatus which serves as a baseline for operation of the pulsatile inflation and deflation of the balloon. A triggering circuit reads the baseline signal and generates a control signal to selectively generate valves interconnecting the angioplasty catheter with sources of inflation media and low pressure. Time delay circuits may be utilized which delay either the duration of the control signal or the receipt thereof by the control valves.
62 citations
TL;DR: Numerical simulations of pulsatile, non-Newtonian blood flow through life-like femorodistal bypass models have been performed to determine whether haemodynamic benefits arise from the modified geometry of the Taylor anastomosis.
62 citations
TL;DR: It is concluded that catecholamines and the renin-angiotensin system contribute to the production of postoperative hypertension and that pulsatile flow diminishes renin stimulation, which results in a decreased incidence of postoperatively hypertension.
62 citations
TL;DR: Findings indicate acute psychosocial stress inhibits pulsatile LH secretion, at least in part, by reducing pituitary responsiveness to GnRH, implicating an additional pathway of suppression that is independent of cortisol acting via this receptor.
Abstract: This study assessed the importance of cortisol in mediating inhibition of pulsatile LH secretion in sheep exposed to a psychosocial stress. First, we developed an acute psychosocial stress model that involves sequential layering of novel stressors over 3-4 h. This layered-stress paradigm robustly activated the hypothalamic-pituitary-adrenal axis and unambiguously inhibited pulsatile LH secretion. We next used this paradigm to test the hypothesis that cortisol, acting via the type II glucocorticoid receptor (GR), mediates stress-induced suppression of pulsatile LH secretion. Our approach was to determine whether an antagonist of the type II GR (RU486) reverses inhibition of LH pulsatility in response to the layered stress. We used two animal models to assess different aspects of LH pulse regulation. With the first model (ovariectomized ewe), LH pulse characteristics could vary as a function of both altered GnRH pulses and pituitary responsiveness to GnRH. In this case, antagonism of the type II GR did not prevent stress-induced inhibition of pulsatile LH secretion. With the second model (pituitary-clamped ovariectomized ewe), pulsatile GnRH input to the pituitary was fixed to enable assessment of stress effects specifically at the pituitary level. In this case, the layered stress inhibited pituitary responsiveness to GnRH and antagonism of the type II GR reversed the effect. Collectively, these findings indicate acute psychosocial stress inhibits pulsatile LH secretion, at least in part, by reducing pituitary responsiveness to GnRH. Cortisol, acting via the type II GR, is an obligatory mediator of this effect. However, under conditions in which GnRH input to the pituitary is not clamped, antagonism of the type II GR does not prevent stress-induced inhibition of LH pulsatility, implicating an additional pathway of suppression that is independent of cortisol acting via this receptor.
62 citations
TL;DR: The amplitude and phase of the pressure gradient over the stenosis, relative to those in a normal section of artery, were found to be sensitive indicators of stenosis development.
62 citations