Design of a Cardiovascular Blood Flow Simulator and Utilization in Hemodynamic Evaluation of Mechanical Circulatory Support Devices.

Abstract

Increasing numbers of old and sick patients who are no longer eligible for prolonged invasive implantation surgery have encouraged many researchers to investigate the development of a Mechanical Circulatory Support (MCS) device with more reliability and less possible invasive complications, which would benefit the majority of patients. This thesis will test experimentally and numerically the feasibility of installing an MCS device, as a bridge to destination, in the descending aorta, in a series configuration with the heart. To this end, a multi-chamber Simulator of the Cardio-Vascular blood-flow Loop (SCVL) was designed to simulate the in-vitro flow rates, pressures and other parameters representing normal and diseased conditions of the human cardiovascular system. The multi-chamber SCVL includes models for all four chambers of the heart, and the systemic as well as the pulmonic circulations. Next, a comprehensive study was conducted using the SCVL system to compare the novel in-series placement of the pump, in the descending aorta, with traditional in-parallel placements. Then, a comprehensive numerical study was conducted using the modified Concentrated Lumped Parameter (CLP) model developed by the same team. The numerical results are compared and verified by the experimental results under various conditions. The results for the pump installed in the descending aorta show that the pressure drop, upstream of the pump, facilitates the cardiac output as a result of after-load reduction. However, at the same time the generated pressure drop at the proximal part of the descending aorta induces a slight drop in the carotid perfusion which will be autoregulated by the brain in a native system. Further, the pressure rise downstream of the pump improves the blood perfusion in the renal artery. The pulse wave analysis show that the placement of the pump in the descending aorta leads to improved pulsatility which is beneficial for end-organ functionality in the native cardiovascular system.