A COMPUTER MODEL OF THE PEDIATRIC CIRCULATORY SYSTEM FOR TESTING PEDIATRIC ASSIST DEVICES

Abstract

To predict hemodynamic responses of mechanical circulatory support devices in the pediatric circulation, computer models of the circulatory systems for one and four year olds were developed. Model parameters were adjusted to match the hemodynamic pressure and flow waveforms, percent systole, and heart rate from 6 pediatric patients with normal ventricles. Left ventricular failure was modeled by adjusting the time-varying compliance curve of the left heart to produce aortic pressures (AoP) and cardiac outputs (CO) consistent with clinical observations. Models of a continuous flow (CF) and pulsatile flow (PF) pediatric ventricular assist device (VAD) and intra aortic balloon pump (IABP) were developed and integrated to the model. Simulations were conducted to predict acute hemodynamic responses to PF and CF VAD operating at 50%, 75% and 100% support and 2.5 and 5 ml IABP. PF VAD, CF VAD, and IABP increased CO, mean AoP and mean coronary flow (CoF) and reduced left ventricular work (LVEW) with increasing levels of support. CF VAD decreased aortic pressure pulsatility with increasing levels of support while PF VAD and IABP maintained physiologic aortic pulse pressures. Although both CF and PF VAD reduce ventricular volume toward the normal range, the variation in end-systolic and end-diastolic volume (ΔV) for CF diminishes with increasing levels of VAD support compared to PF VAD which maintains a normal physiologic ΔV. Computer simulation may aid in development of pediatric devices and control strategies.