Trileaflet valve hydrodynamic resistance assessment.

Valve hydrodynamic performance is usually assessed by effective orifice area, transvalvular resistance, regurgitation and blood damage effect. Some studies suggest effects in effective orifice area due to cardiovascular resistance, compliance and angle position of the valve. We suppose that silicone rubber valves under study have a good performance under different cardiovascular resistance conditions. Two in vitro experiments were made to test this hypothesis under constant and pulsatile flow rate. Transvalvular gradient pressure, transvalvular resistance, Gorling effective orifice area, effective orifice area in the ascending aorta and Reynolds numbers were estimated in both flow rates. Results suggest that cardiovascular resistance has no significant effect for this kind of valves, however resistance effect is observed in pumping pressure. Small transvalvular resistance and transvalvular pressure gradients were found. Gorlin effective orifice areas greater than 0.3 cm(2) have not viscosity effect. P-value 0.001 was found between Gorlin effective orifice area under constant and pulsatile flow rate.