A Physiologically Relevant, Simple Outflow Boundary Model for Truncated Vasculature

Abstract

A realistic outflow boundary condition model for pulsatile flow in a compliant vessel is studied by taking into account physiological effects: compliance, resistance, and wave reflection of the downstream vasculature. The new model extends the computational domain with an elastic tube terminated in a rigid contraction. The contraction ratio, the length, and elasticity of the terminal tube can be adjusted to represent effects of the truncated vasculature. Using the wave intensity analysis method, we apply the model to the test cases of a straight vessel and the aorta and find good agreement with the physiological characteristics of blood flow and pressure. The model is suitable for cardiac transient (non-periodic) events and easily employed using so-called black box software.

Fast and Accurate Pressure-Drop Prediction in Straightened Atherosclerotic Coronary Arteries

“…However, it cannot be visualized directly with the available imaging techniques. Although several models have already modeled the microcirculation, 10,16,17 further research is still needed for the resistance distal to diseased coronary arteries. A third requirement is that the lumen segmentations in a clinical setting are based on automatic reconstructions from (bi-plane) angiography, while in this study patient-specific lumen data from IVUS were used which have more detail.…”

A numerical model of pulsatile blood flow in compliant arteries of a truncated vascular system

“…(1), while the vessel lengths were calculated using Eq. (2). Accordingly the taper angle used in this study corresponds to 0.54°, which is within the physiological range as determined by in vivo studies.…”

“…4, to represent the compliance, the wave reflection, and the pressure drop due to the small arteries, arterioles, and capillaries that would follow the truncated vascular system. The Young's modulus and the length of the elastic tube are selected by the following relations to match the compliance, C, and wave arrival time, t arr [2]:…”

“…An outflow boundary model, proposed by Pahlevan et al [2], is used to specify the boundary condition at the four outlets. This outflow boundary model extends the computational domain with a straight elastic tube and contraction tube, as shown in Fig.…”

“…The dynamics of blood flow are an underlying factor in many of these diseases and a better understanding of blood flow dynamics plays an especially important role in the diagnosis and treatment of these diseases. A better understanding of blood flow dynamics is also essential in the design and performance evaluation of cardiovascular devices such as left ventricular assist devices, artificial heart valves, stents, and grafts [2]. There are two methods that can be used to investigate blood flow in the cardiovascular system: in vivo studies and computational studies.…”