Computational modeling of a tri-leaflet mechanical heart valve

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

25 al 27 de agosto de 2009, Rosario, Santa Fe, Argentina.

Taller; 1º Taller de Órganos Artificiales, Biomateriales e Ingeniería de Tejidos” (BIOOMAT; 2009

Asociacion Argentina de Biomateriales

A tri-leaflet mechanical heart valve was designed for getting the central flow and hemodynamic performance of a native valve. This trileaflet valve was designed using computational fluid dynamic modeling, solving the mathematical equations of the fluid flow assumed laminar and steady state flow. Following the premise of design a mechanical valve with three leaves, no obstruction in the center of the valve and peripheral pivots similar to a native valve, the optimum design was reached by progressive changes in the form. This design was compared with a standard bi-leaflet mechanical valve and a simplified model of a native valve. A right artery of 24 mm in diameter and aortic sinus whit rigid wall is assumed. For the comparison, the valves were located in this artery at 80 mm of the inlet and 200 mm of the outlet. Prosthetic valves of 24 mm in inner diameter were placed in suprananular position, with the leaves totally opened. The optimum design of the tri-leaflet valve shows that the effective surface area for flow across the valve is 84% of the total valve section; with that design the 98% of the flow is central. On the other hand, in the bi-leaflet valve the effective surface area is 79% of the total valve section, and the flow is divided in three channels: two laterals (76%) and one central (24%). For a stable flow of 5000 cm≈/min the pressure drop across the tri-leaflet valve is of 0.07 mmHg, considerably lower than the 0.17 mmHg for the bi-leaflet valve. As reference, the pressure drop calculated by our model of a native valve in the same conditions is of 0.045 mmHg. The shear stress for the tri-leaflet valve is 80% lower than for the bi-leaflet valve. It is concluded that this tri-leaflet mechanical valve design achieves a large central flow, which due to the large central area produce a reduced pressure drop and a lower shear stress than for the bi-leaflet valve and consequently a low consumption of energy and a lower risk for trombogenicity, slightly larger to the expected in a native valve.