Evaluation of prosthetic heart valve performance by a time integrated power loss analysis

Traditional evaluation of heart valve prosthesis (HVP) by the method of transvalvular pressure drop and percentage of flow regurgitation has shown discrepancies among investigators. In order to alleviate the ambiguities associated with this type of approach, a phase-by-phase analysis based on the time integrated power loss through a HVP is proposed. The theoretical basis and physical significance for such an analysis are discussed by Stibdividing the cardiac cycle into three phase categories: the ejection phase, the dynamic regurgitation phase, and the leakage phase. The summation of HVP power losses during each of these three phases constitute the total power loss (TPL) for the HVP during the cardiac cycle. Utilizing a mock circulatory flow loop to produce physiologic pressure and flow waveforms, the performance of five current aortic HVPs and four current mitral HVPs is examined by the power loss analysis. The TPL illustrates an upward trend with increasing heart rate. At heart rates less than 90 bpm, results indicated the ejection phase power losses (EPL) dominated the TPL for the valves, and at heart rates greater than 90 bpm, the TPL was influenced to a greater extent by the regurgitation phase power losses (RPL) than the EPL.