Late ball variance with the Model 1000 Starr-Edwards aortic valve prosthesis. Risk analysis and strategy of operative management.

The first generation of aortic ball-valve prostheses, used until 1965, was associated with poppet damage owing to fatty infiltration of the silicone rubber ball, a phenomenon termed ball variance. For the Model 1000 Starr-Edwards valves, almost all cases were discovered before 8 years. However, a review of our patients still at risk with the original valve and poppet, prompted by other recent reports of late ball variance, has shown that severe variance can exist up to 20 years after implantation. There is a relationship between the year of valve implantation and the timing and severity of ball variance for the overall series of patients surviving operation, but for the subgroup currently at risk the sample sizes are too small to detect any difference, if one still exists. Only three of 12 patients in the current subset were found to have severe variance. Simple ball change has been the operation of choice. Prophylactic reoperation is not indicated in the current subset, but patients require careful follow-up and should be considered for reoperation should symptoms develop.