Publication Date

2016

Document Type

Thesis

Committee Members

Mark Anstadt (Committee Member), Chandler Phillips (Committee Member), David Reynolds (Advisor)

Degree Name

Master of Science in Biomedical Engineering (MSBME)

Abstract

Most conventional cardiac assist devices today employ continuous flow blood pumps to supplement function in the dysfunctional heart. Continuous flow pumps are predominantly preferred to the original pulsatile pumps due to the smaller size (greater implantability) and higher efficiency they achieve. However, interest in the impact of vascular pulsatility on human health has arisen from the growing evidence of higher complications with nonpulsatile devices compared to pulsatile devices. Direct cardiac compression (DCC) offers a unique solution to the pulsatility issue through the application of force directly to the heart's surface. It is believed that employing the existing pump architecture of the heart better produces natural pulsatility than blood pumps in series with the heart. The purpose of this study was to determine if external cardiac compression by direct mechanical ventricular actuation (DMVA), produces arterial pulsatile quality to that of the naturally beating heart. This concept was tested using DMVA, a non-blood contacting DCC device capable of actively augmenting diastole, on an acute fibrillating model in nine large animals (seven canine and two swine). Hearts, being fibrillated in order to eliminate the heart's natural function to generate pulsatile blood flow, were supported by the DMVA device. Progressive myocardial weakening and acute failure throughout the experiment resulted from repeated cycles of fibrillation and defibrillation. Aortic pressures and flows were recorded periodically in ten second captures. Conventional measures of pulsatility (pulse pressure, energy equivalent pressure, surplus hemodynamic energy, frequency pulsatility index) were computed from these captures for comparison of arterial pulsatility between the naturally beating heart and the fibrillating heart supported by DMVA. Pulsatility in the naturally beating heart was measured from both the healthy normal heart and the weakened heart. Mean aortic flows and pressures were equivalent between DMVA condition and unsupported weakened heart condition. The results suggests pulsatile similarity between DMVA support for the fibrillating heart and the unsupported naturally beating heart. No index of arterial pulsatility was significantly lower from DMVA support heart compared to the unsupported beating heart at the same level of cardiac output (p>0.05). DMVA proved able to restore arterial blood flow pulsatility in the fibrillating heart compared to the naturally beating heart.

Page Count

78

Department or Program

Department of Biomedical, Industrial & Human Factors Engineering

Year Degree Awarded

2016

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