Observation of cavitation pits on a mechanical heart valve surface in an artificial heart used in in vivo testing.

The aim of this study was to observe mechanical heart valve (MHV) cavitation pits resulting from in vivo testing of an electrohydraulic total artificial heart (EHTAH). During in vivo testing with three sets of valves (one set used in two animals), the slope of the driving pressure (left and right driving pressure) was used as a factor for investigating cavitation intensity, and the occurrence of cavitation was determined by the observation of cavitation pits on the explanted valve surfaces. Medtronic Hall valves were installed at the inlet and outlet positions of the two blood pumps. The EHTAH was tested using calves weighing 69-80 kg. The cavitation pits on the valve surface of the inlet valves of the left and right blood pumps were examined by scanning electron micrography. The driving pressure slope 5 ms before valve closure exceeded the cavitation threshold during in vitro testing. On both inlet valves, many large pits formed when the driving pressure slope was high and the pump operating time was long. When estimating cavitation intensity during in vivo testing, both a high driving pressure slope and a long operating time are important factors. The cavitation pits observed on the valve surfaces resulting from in vivo testing will eventually lead to leaflet fracture.