An attempt to evaluate prosthetic heart valves in terms of fluid mechanics

Abstract

In order to elucidate performance characteristics of a few prosthetic heart valves, the present in vitro study was carried out to investigate disturbances of flow past the prostheses. Measurements of pressure and velocity around, and visualization of flow across, the valves were made with three kinds of the valves attached to the entrance of a metacrylate model of the aorta. Comparison of the pressure drops caused by these valves with those by plate orifices revealed that the prostheses corresponded to the orifices, the opening area of which was approximately 45% of the cross-sectional area of the inlet section. The pressure drop by the Björk-Shiley valve was smaller than the drops by the Kay-Suzuki and the SAM-MT valves. Highly turbulent flow taking place downstream of the valves seemed to be responsible for the energy loss induced by the valves. The structure of the turbulence was studied in association with the formation of thrombi and focal vascular lesions.