Interaction of the Cardiovascular System with an Implanted Rotary Assist Device: Simulation Study with a Refined Computer Model>

Abstract

In recent years, implanted rotary pumps have achieved the level of extended clinical application including complete mobilization and physical exercise of the recipients. A computer model was developed to study the interaction between a continuous-flow pump and the recovering cardiovascular system, the effects of changing pre- and afterloads, and the possibilities for indirect estimation of hemodynamic parameters and pump control. A numerical model of the cardiovascular system using Matlab Simulink simulation software was established. Data of circulatory system modules were derived from patients, our own in vitro and in vivo experiments, and the literature. Special care was taken to simulate properly the dynamic pressure-volume characteristics of both left and right ventricle, the Frank-Starling behavior, and the impedance of the proximal vessels. Excellent correlation with measured data was achieved including pressure and flow patterns within the time domain, response to varying loads, and effects of previously observed pressure-flow hysteresis in rotary pumps. Potential energy, external work, pressure-volume area, and other derived heart work parameters could be calculated. The model offers the possibility to perform parameter variations to study the effects of changing patient condition and therapy and to display them with three-dimensional graphics (demonstrated with the effects on right ventricular work and efficiency). The presented model gives an improved understanding of the interaction between the pump and both ventricles. It can be used for the investigation of various clinical and control questions in normal and pathological conditions of the left ventricular assist device recipient.

A Preload and Afterload Sensitive Artificial Ventricle to Test Cardiovascular Prostheses

“…The ventricle is modeled by the time varying differential elastance model with internal resistance (Arabia et al, 2003), (Vollkron et al, 2002) and (Campbell et al, 1984). This model links the instantaneous ventricular pressure with the instantaneous ventricular volume in one cardiac cycle.…”

Simulation and enhancement of a cardiovascular device test rig

“…Resistance, compliance and inertiance were also incorporated in this model. Cardiovascular system models have also been created by other groups (Vollkron et al, 2002;Wu et al, 2003;Vrettos, 2005;Hassani et al, 2007), however, the mentioned simulations concentrate solely on the cardiovascular system, and do not provide an accurate representation of an MCL.…”

Effects of Muscle Pump on Rotary Blood Pumps in Dynamic Exercise: A Computer Simulation Study

“…To achieve this primary goal, the interaction between the circulatory system and RBPs needs to be thoroughly analyzed. Computer simulation is one important tool that has been widely used to study this interaction due to its flexibility and low cost (Avanzolini et al 1988;Xu and Fu 2000;Zhou et al 1999;Vollkron et al 2002). In most computer simulation model developed, the exercise is simulated by the drop of peripheral resistance plus the increase of heart rate and heart contractility.…”