A new concept on mechanical heart valve, new design and materials

AMERIO, O. N.; MARIO ROBERTO ROSENBERGER; SCHVEZOV, C. E.

Buenos Aires

Congreso; 19th World Congress of the World Society of Cardio-Thoracic Surgeons; 2009

Two objectives were proposed in this work: design a tri-leaflet mechanical valve with central flow closest to the flow of a native valve and select the optimal material for building the valve with good haemocompatibility. It will meet an optimum hemodynamic performance with low thrombogenicity. The effect of the morphological design on the blood flow across the valve is studied employing computational fluid dynamic modeling with the finite element method. The results of the flow for a tri-leaflet valve are compared with the flows obtained for a standard prosthetic bi-leaflet valve. The design of this tri-leaflet valve shows the effective surface area for flow across the valve is 84% of the total valve section. In addition 98% of the flow is central. For a stable flow of 5,000 cm³/min the pressure drop across the tri-leaflet valve is of 0.055 mmHg, considerably lower than for the bi-leaflet valve which is of 0.080 mmHg. The shear stress, a parameter that increases the potential for thrombogenicity, for the tri-leaflet valve is 80% lower than for the bi-leaflet valve. With respect to the valve fabrication the material selected is a titanium alloy coated with a layer of titanium dioxide. In this way the good mechanical properties of the titanium alloy is combined with an oxide layer with a good haemocompatibility.  It is concluded that an optimum hemodynamic performance was achieved in this design meeting the central flow, a low pressure drop across the valve, and a low shear stress. These factors plus a good hemocompatible material will reduce the risk for thrombogenicity.