Power losses through mechanical heart valve prostheses

A new parameter for the evaluation of the performance of heart valve prosthesis (HVP) is developed. The mean power loss is computed from the pressure drop and the flow through HVPs obtained in a pulsatile mock loop system. Eight mechanical HVPs are studied (five in the mitral position and three in the aortic position). The power loss is categorized into three periods within a heart cycle: the first two periods together constitute the ejection power loss (EPL). The last period is the power loss due to regurgitation (RPL). The discussion is more concerned about the mitral HPVs because, in the aortic position, the conditions of measurements combined with the potential energy storage in the elastic aorta make the results less interpretable. The results indicate that EPL closely reflects the closure behavior of the valve occluder and the mean transvalvular pressure drop. RPL is much higher (almost IO times more) than EPL. The overall power loss (OPL) shows that RPL is more important compared to EPL. OPL evaluates the relative Influence of energy losses resulting from the pressure drop and regurgitation volume, and defines a unique performance parameter.