Numerical Simulation of Nonpulsatile Left Ventricular Bypass

Abstract

A computer simulation was carried out to investigate the influence of nonpulsatile left ventricular assistance on hemodynamics. A simulation circuit was constructed to represent the circulatory system. A source of current was added to denote the nonpulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. We introduced a pulsatility indicator (PI) to clarify the pulsatility characteristics in the hemodynamics; this PI was defined as the ratio of the pulse pressure (PP) to the mean aortic pressure (AoP). When nonpulsatile bypass flow increased, the mean AoP, tension time index (TTI), and diastolic pressure time index (DPTI) increased, and cardiac output, PP, and PI decreased. When assisted flow increased with the constant total flow rate, the mean AoP and DPTI changed little; the PP, TTI, and PI decreased, and the endocardial viability rate increased. The PI would be helpful in evaluating the effect of pulsatility.

Study of Left Ventricular Bypass Using Wankel Type Semipulsatile Blood Pump

“…Those parameter changes are similar to those of our previous simulation studies on a type of nonpulsatile bypass pump (11). However, although the PI was small, the pulse of the AoP curve was clearly identified with semipulsatile assistance.…”

“…Each parameter used for the calculation is shown in Table 1. These parameters were based upon our previous studies (8–11) and other studies (13,14). The tension time index (TTI), the diastolic pressure time index (DPTI), the endocardial viability ratio (EVR), and the pulsatility indicator (PI) were also calculated according to the equations below:…”

“…The circulatory simulation circuit, governing equations, numerical method, and computational procedure are described subsequently, which are similar to those we have previously reported (11).…”

“…On the other hand, computer simulations of the circulatory system are being employed to investigate hemodynamics (5–7). We have developed a simple numerical simulation circuit and studied the effect of the total artificial heart, intraaortic balloon pumping, biventricular assistance and nonpulsatile left ventricular bypass (8–11). In this paper, the effect of a Wankel type semipulsatile left ventricular assist pump was investigated with computer simulation and an animal experiment.…”

An Electro‐Fluid‐Dynamic Simulator for the Cardiovascular System

“…Ventricular elastance is defined as the relation between the variation of the ventricular pressure and volume. In general, the ventricle is modeled as a time variable elastance (8–11). The graphic representation of elastances is performed through the cardiac work cycle in a Pressure × Volume ( P × V ) diagram (12), as presented in Fig.…”