A numerical simulation of mechanical heart valve closure fluid dynamics.

A computational fluid dynamics model for the analysis of the bileaflet mechanical heart valve closure process is presented. The objective of the study is to demonstrate the ability of the numerical model to simulate the leaflet motion during the closing phase in order to investigate the closure fluid dynamics and to evaluate the effect of alterations in the leaflet tip geometry. The model has been applied to six different combinations of the leaflet tip geometry and the gap width between the leaflet tip and the housing. The results show that the negative pressure quickly develops on the atrial side of the leaflet tip. The pressure becomes more negative as the leaflet closure progresses and the lowest pressure is reached before the leaflet comes to a stop in the closed position. The flow dynamics at the instant of valve closure is strongly dependent on the leaflet velocity during the closing phase. Decrease of the tip velocity by a factor of three in the last four degrees of leaflet motion leads to a 50% reduction in the negative pressure magnitude.