Hemodynamics of various designs of 19 mm pericardial aortic valve bioprosthesis

Abstract

The hemodynamics of five designs of 19 mm pericardial aortic valve bioprostheses were examined in 47 resting patients by Doppler echocardiography. The salient differences among the five designs are that valve leaflets are mounted inside the support frame in one (the Carpentier-Edwards valve, evaluated in 4 patients) and outside the frame in the other four (the Ionescu-Shiley (16 patients), Mitroflow (4), Bioflo (8) and Labcor-Santiago (15)); and that two models have either total (Bioflo) or partial (Labcor-Santiago) protective pericardial sheaths on the stent, while the other three do not. The hemodynamic parameters determined included transvalvular pressure drop, valve area, left ventricular outflow tract diameter, subvalvular/valvular velocity ratio and subvalvular/valvular velocity-time integral ratio. 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 outflow tract diameter and subvalvular velocity (r = -0.66, P < 0.001) confirmed the need to correct for prevalvular velocities when using the Bernouilli equation to calculate the pressure drop across small pericardial aortic valve bioprostheses. The Bioflo design caused significantly greater pressure drops (peak 38.3 +/- 8.3 mmHg, mean 24.6 +/- 4.8 mmHg) and smaller areas (0.82 +/- 0.17 cm2) than the Ionescu-Shiley (20.3 +/- 5.6 and 11.7 +/- 3.8 mmHg, 1.19 +/- 5.3 and 10.1 +/- 3.1 mmHg, 1.27 +/- 0.12 cm2) valves.

A novel comparison of stentless versus stented valves in the small aortic root

“…Intuitively, surgeons avoid inserting 19-or 21-mm bioprostheses in patients with a body surface area above 1.7 m 2 . 2,9,10 The alternatives to implanting a small bioprosthesis include mechanical valve replacement, patch enlargement of the aortic anulus, 3 or implantation of a stentless bioprosthesis. 15,19 Mechanical valves have a proportionally larger effective orifice area for a given anulus size and have been shown to produce lower gradients when compared with similarly sized bioprostheses.…”

“…15,19 Mechanical valves have a proportionally larger effective orifice area for a given anulus size and have been shown to produce lower gradients when compared with similarly sized bioprostheses. 8,10 However, elderly patients are at increased risk for anticoagulant-related hemorrhage; therefore mechanical valve replacement may be inadvisable. Sommers and David 3 demonstrated that anulus-enlarging procedures resulted in long-term survivals comparable with those of patients receiving larger aortic prostheses; however, the operative mortality of aortic valve replacement increased from 3.5% to 7.1% when enlargement of the aortic anulus was performed.…”

“…6 Experienced surgeons can then decide to choose a different prosthesis, perform an annular enlarging procedure, 3 or alternatively insert the valve in a supra-annular position.When comparing bioprostheses from different manufacturers, most authors have stratified their analyses on the basis of the industry-labeled valve size. [7][8][9][10] Unfortunately, recent reports have demonstrated a discrepancy between the labeled valve size and the actual dimensions of the valve or its sizer. 11,12 Furthermore, in a previous study we demonstrated that the industrylabeled valve size bore no relation to any hemodynamically significant dimension and varied considerably among manufacturers.…”