Stent fracture in Wessex porcine heart valve bioprostheses.

By January 1994, a total of 40 Wessex porcine bioprostheses (21 mitral, 18 aortic, and 1 tricuspid) were explanted from 31 subjects. They belonged to a series of 150 patients who received 184 of such prostheses in our unit. Seventeen of these explanted prostheses were available for study, and 11 of them presented some sort of stent fracture or fissuring (mean of 3.6 +/- 1.6 fractures per prosthesis). The disruption occurred in all cases at the base of the commissural arch or at the commissural bar of the stent. The fractures were not detected clinically nor echo-cardiographically before reoperation, and most valves were explanted for reasons other than the stent rupture itself. The actuarial probability of freedom from stent fracture in our series is 66 +/- 12% at 9 years of follow-up. In our experience, fracture of the stent is an important mode of structural dysfunction of the Wessex porcine bioprostheses.