A SIMPLE IN-LINE PULSE WAVE DEVICE RESTORES PULSATILE PRESSURE DURING, AND BARORECEPTOR CONTROL AFTER CARDIOPULMONARY BYPASS

ASAIO Journal ◽  
1999 ◽  
Vol 45 (2) ◽  
pp. 150
Author(s):  
C McCotter ◽  
Y S Sun ◽  
R M Lust
Author(s):  
Jifeng Peng ◽  
Lili Zheng ◽  
Michael Egnor ◽  
Mark Wagshul

In this paper, a computational study was carried out to investigate the CSF dynamics in the spinal cavity. A theoretical and computational model was developed to simulate the pulsatile CSF flow and the deformation of the spinal cavity that results from transmission of the CSF pulse wave from the cranial cavity. Under a pulsatile pressure gradient, the velocity profile of the flow is blunt for large Womersley numbers, while for small Womersley numbers the velocity profile is parabolic. The phase relationship between the pressure and the velocity is also related to Womersley number. This is the first step to understand the pulsatile dynamics of the CSF in the spinal cavity and will help explain the cause of related diseases and improve the clinical treatment.


2001 ◽  
Vol 16 (5) ◽  
pp. 307
Author(s):  
Harumasa Takano ◽  
Nobutaka Motohashi ◽  
Tetsuji Nakai ◽  
Hidenori Atsuta ◽  
Shunsuke Kitou ◽  
...  

Author(s):  
Eleonora Tubaldi ◽  
Marco Amabili ◽  
Michael P. Paidoussis

In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron vascular prosthesis is modelled as a transversely isotropic circular cylindrical shell described by means of nonlinear Novozhilov shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. An input oscillatory pressure at the shell entrance is considered and it propagates down the shell causing a wave motion within the shell where, as a consequence, the pressure gradient and the flow velocity are functions of both the axial coordinate and time. For the first time in literature, coupled fluid-structure Lagrange equations for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity changes’ propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron vascular graft conveying blood flow. A pulsatile time-dependent blood flow model is considered in order to study the effect of pressurization by applying the first and second harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure considering the propagation of pressure and velocity changes inside the shell are here presented via frequency-response curves and time histories. It is shown how traveling waves of pressure and velocity cause a delay in the radial displacement of the shell at different values of the axial coordinate. This study provides a deep insight into the currently unknown nonlinear behavior of vascular prostheses whose dynamic response can cause unwanted hemodynamic effects leading to failure. Indeed, it is well known that vascular prostheses mechanical properties are very different from those of natural arteries. In particular, the compliance mismatch between the host artery and the prosthesis causes a different wave speed resulting in a change in the performance of the cardiovascular system. In the near future, a more refined model to the one here presented will be applied to reproduce and compare the dynamic behavior of vascular prostheses and the human aorta, helping in vascular prostheses design and implementation.


2016 ◽  
Vol 34 (Supplement 1) ◽  
pp. e123-e124
Author(s):  
Jie Dong ◽  
Hongbo Dong ◽  
Peiyu Ye ◽  
Yinkun Yan ◽  
Jie Mi
Keyword(s):  

Author(s):  
Qingping Yao ◽  
Danika M. Hayman ◽  
Qiuxia Dai ◽  
Merry L. Lindsey ◽  
Hai-Chao Han

Arteries are subjected to a pulsatile pressure centered on a constant mean pressure in vivo. This oscillating pressure may increase due to atherosclerotic and age-related wall stiffening, or may be disrupted by the use of cardiopulmonary bypass machines and ventricular assist devices. Previous research has reported that restoration of pulsatile flow improves microcirculation and blood flow to the organs, however little is known about how pulsatile pressure affects the vasculature.


2020 ◽  
Vol 33 (4) ◽  
pp. 291-296 ◽  
Author(s):  
Yi Zhang ◽  
Patrick Lacolley ◽  
Athanase D Protogerou ◽  
Michel E Safar

Abstract BACKGROUND Arterial stiffness—typically assessed from non-invasive measurement of pulse wave velocity along a straight portion of the vascular tree between the right common carotid and femoral arteries—is a reliable predictor of cardiovascular risk in patients with essential hypertension. METHODS We reviewed how carotid-femoral pulse wave velocity increases with age and is significantly higher in hypertension (than in age- and gender-matched individuals without hypertension), particularly when hypertension is associated with diabetes mellitus. RESULTS From the elastic aorta to the muscular peripheral arteries of young healthy individuals, there is a gradual but significant increase in stiffness, with a specific gradient. This moderates the transmission of pulsatile pressure towards the periphery, thus protecting the microcirculatory network. The heterogeneity of stiffness between the elastic and muscular arteries causes the gradient to disappear or be inversed with aging, particularly in long-standing hypertension. CONCLUSIONS In hypertension therefore, pulsatile pressure transmission to the microcirculation is augmented, increasing the potential risk of damage to the brain, the heart, and the kidney. Furthermore, elevated pulse pressure exacerbates end-stage renal disease, particularly in older hypertensive individuals. With increasing age, the elastin content of vessel walls declines throughout the arterial network, and arterial stiffening increases further due to the presence of rigid wall material such as collagen, but also fibronectin, proteoglycans, and vascular calcification. Certain genes, mainly related to angiotensin and/or aldosterone, affect this aging process and contribute to the extent of arterial stiffness, which can independently affect both forward and reflected pressure waves.


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