THE INFLUENCE OF THE DESIGN ON THE MEDIUM TO LONG-TERM HEMODYNAMIC BEHAVIOR OF 19 MM PERICARDIAL AORTIC-VALVE PROSTHESES

Background and aims of the study: The hemodynamics of five designs of 19 mm pericardial aortic valve bioprosthesis were examined by Doppler echocardiography in 48 resting patients at medium or long term follow up. Methods: The salient differences among the five designs are that v alve leaflets are mounted inside the support frame in one (the Carpent ier-Edwards valve, evaluated in five patients) and outside the frame i n the other four (the Ionescu-Shiley (14 patients), Mitroflow(six pati ents), Bioflo (eight patients) and Labcor-Santiago (15 patients)); and that two models have either total (Bioflo) or partial (Labcor-Santiag o) protective pericardial sheaths on the stent, while the other three do not. The hemodynamic parameters determined included transvalvular p ressure drop, valve area, left ventricular outflow tract diameter, sub valvular/valvular velocity ratio and subvalvular/valvular velocity-tim e integral ratio. Results: There were no significant differences among the various valves as regards left ventricular outflow tract diameter , subvalvular/valvular velocity ratio or subvalvular/valvular velocity -time integral ratio. Negative correlation between left ventricular ou tflow tract diameter and subvalvular velocity (r = -0.63, p<0.001) con firmed the need to correct for prevalvular velocities when using the B ernoulli equation to calculate the pressure drop across small pericard ial aortic valve bioprostheses. The Bioflo design caused significantly greater pressure drops (peak 49.6 +/- 11.3 mmHg, mean 28.1 +/- 6.1 mm Hg) and provided smaller areas (0.80 +/- 0.16 cm(2)) than the Ionescu- Shiley (26.7 +/- 6.6 and 15.2 +/- 4.1 mmHg, 1.17 +/- 0.17 cm(2)) and L abcor-Santiago (24.8 +/- 5.9 and 15.1 +/- 3.7 mmHg, 1.24 +/- 0.12 cm(2 )) valves. Conclusions: Of the currently available 19 mm bovine perica rdium heart valve bioprostheses, the Mitroflow and Labcor-Santiago val ves, in both of which the leaflets are mounted outside the stent, have better hemodynamics in the aortic position than the Carpentier-Edward s valve, which has internal leaflet mounting, Sheathing the stent tota lly in pericardium, as in the withdrawn Bioflo valve, gives rise to re latively poor hemodynamics.