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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109 citations
TL;DR: Numerical results obtained for the positive taper angle show that the blood flow characteristics such as the axial velocity profiles, flow rate and wall shear stress have lower values, while the resistive impedances have higher values than the Newtonian model.
109 citations
TL;DR: It is demonstrated that by judiciously applying fluid shear stress, cell signaling cascades can be augmented with subsequent profound effects on cardiac tissue regeneration, as compared to static-cultivated constructs.
Abstract: Deciphering the cellular signals leading to cardiac muscle assembly is a major challenge in ex vivo tissue regeneration. For the first time, we demonstrate that pulsatile interstitial fluid flow in three-dimensional neonatal cardiac cell constructs can activate ERK1/2 sixfold, as compared to static-cultivated constructs. Activation of ERK1/2 was attained under physiological shear stress conditions, without activating the p38 cell death signal above its basic level. Activation of the ERK1/2 signaling cascade induced synthesis of high levels of contractile and cell-cell contact proteins by the cardiomyocytes, while its inhibition diminished the inducing effects of pulsatile flow. The pulsed medium-induced cardiac cell constructs showed improved cellularity and viability, while the regenerated cardiac tissue demonstrated some ultra-structural features of the adult myocardium. The cardiomyocytes were elongated and aligned into myofibers with defined Z-lines and multiple high-ordered sarcomeres. Numerous intercalated disks were positioned between adjacent cardiomyocytes, and deposits of collagen fibers surrounded the myofibrils. The regenerated cardiac tissue exhibited high density of connexin 43, a major protein involved in electrical cellular connections. Our research thus demonstrates that by judiciously applying fluid shear stress, cell signaling cascades can be augmented with subsequent profound effects on cardiac tissue regeneration.
109 citations
TL;DR: The results indicate that, with reductions in flow at constant pressure in vitro, S/D ratio does not relate to calculated resistance in the same linear manner as PI and RI.
Abstract: Using an in vitro flow model, volume flow and pressure were measured to compare calculated resistance with simultaneously measured continuous-wave Doppler indices during imposed changes in downstream resistance to pulsatile flow. With stepwise reductions in flow, the peak (S) and trough (D) points of the maximum shifted-frequency envelope fell in parallel in a linear fashion until D reached zero. Pressure remained constant, and the pressure waveform remained unchanged. As calculated resistance increased, resistance index (RI) and pulsatility index (PI) both increased in a linear fashion until the point at which D became zero. However, S/D ratio was not linear, and the slope increased as resistance increased. The results obtained from microspheres suspended in water and with heparinized sheep's blood were similar. The results indicate that, with reductions in flow at constant pressure in vitro, S/D ratio does not relate to calculated resistance in the same linear manner as PI and RI.
109 citations
TL;DR: The reflex decrease in arterial pressure is greater and more sustained with elevated pulsatile than with elevated static carotid sinus pressure, and the inhibition of SNA was sustained with the phasic input during pulsatile pressure.
Abstract: The reflex decrease in arterial pressure is greater and more sustained with elevated pulsatile than with elevated static carotid sinus pressure. The purpose of this study was to relate afferent bar...
109 citations