DYNAMIC BEHAVIOR ANALYSIS OF MECHANICAL MONOLEAFLET HEART-VALVE PROSTHESES IN THE OPENING PHASE

In this paper, fluttering behavior of a mechanical monoleaflet tilting disk heart valve prostheses during the opening phase was analyzed. The impact between the occluder and the guiding strut at the fully open position was included in the analysis with a Bjork-Shiley monoleaflet aortic valve. The motion of the valve occluder was modeled as a rotating system, and equations were derived by employing the moment equilibrium principle. Forces due to lift, drag, gravity, and buoyancy were considered as external forces acting on the occluder. The 4th-order Runge-Kutta method was used to solve the governing equations. The results demonstrated that the occluder reaches the steady equilibrium position only after damped vibration. Fluttering frequency varies as a function of time after opening and is in the range of 8-84 Hz. Valve opening appears to be affected by the orientation of the valve relative to gravitational force. The opening velocities are in the range of 0.56-1.37 m/sec and the dynamic loads by impact of the occluder and the strut are in the range of 60-190 N.