Comparison of a new bioprosthetic mitral valve to other commercially available devices under controlled conditions in a porcine model.

BACKGROUND/AIM: To evaluate three mitral bioprostheses (of comparable measured internal diameters) under controlled, stable, hemodynamic and surgical conditions by bench, echocardiographic, computerized tomography and autopsy comparisons pre- and postvalve implantation.

METHODS

Fifteen similar-sized Yorkshire pigs underwent preprocedural computerized tomography anatomic screening. Of these, 12 had consistent anatomic features and underwent implantation of a mitral bioprosthesis via thoracotomy on cardiopulmonary bypass (CPB). Four valves from each of three manufacturers were implanted in randomized fashion: 27-mm Epic, 27-mm Mosaic, and 25-mm Mitris bioprostheses. After CPB, epicardial echocardiographic studies were performed to assess hemodynamic function and define any paravalvular leaks, followed by postoperative gated contrast computerized tomography. After euthanasia, animals underwent necropsy for anatomic evaluation.

RESULTS

All 12 animals had successful valve implantation with no study deaths. Postoperative echocardiographic trans-valve gradients varied among bioprosthesis manufacturers. The 25-mm Mitris (5.1 ± 2.7)/(2.6 ± 1.3 torr) had the lowest peak/mean gradient and the 27-mm Epic bioprosthesis had the highest (9.2 ± 3.7)/(4.6 ± 1.9 torr). Surgical valve opening area (SOA) varied with the 25-mm Mitris having the largest SOA (2.4 ± 0.15 cm2 ) followed by the 27-mm Mosaic (2.04 ± 0.23 cm2 ) and the 27-mm Epic (1.8 ± 0.27 cm2 ) valve. Bench device orthogonal internal diameter measurements did not match manufacturer device size labeling: 25-mm Mitris (23 × 23 mm), 27-mm Mosaic (23 × 22 mm), 27-mm Epic (21 × 21 mm).

CONCLUSIONS

Current advertisement/packaging of commercial surgical mitral valves is not uniform. This study demonstrates marked variations in hemodynamics, valve opening area and anatomic dimensions between similar sized mitral bioprostheses. These data suggest a critical need for standardization and close scientific evaluation of surgical mitral bioprostheses to ensure optimal clinical outcomes.