New approach for replacement of degenerated mitral bioprostheses

OBJECTIVE: The most common indication for reoperation in patients with a mitral bioprosthetic valve is primary tissue failure. Explanation of the bioprosthesis is time-consuming and may be complicated by cardiac rupture at the atrioventricular junction or the posterior left ventricular wall where a strut is imbedded, injury to the circumflex artery and late perivalvular leak. A new approach to avoid these complications by excising only the bioprosthetic tissue and attaching a reversed aortic St. Jude valve to the intact stent has been developed and evaluated. METHODS: We have replaced degenerated mitral bioprostheses with a St. Jude valve in 73 patients during the last 12 years. In 57, including all who had their operation before 1991, explantation was used. The stent was preserved in 16 patients; in the first four we implanted a mitral St. Jude valve (SJM) within the stent, but this only allows a SJM 6-8 mm smaller than the bioprosthesis. We evolved our approach in the last 12 patients to suture a reversed aortic St. Jude valve with extended cuff to the atrial side of the bioprosthetic cuff; this allows the use of a St. Jude valve 2 mm smaller than the bioprosthesis with exact matching of the orifice sizes. The demographic and clinical profiles of the two groups were similar. RESULTS: Operative mortality was 8/57 (14%) in the explantation group and none in the stent-preservation group. Three late perivalvular leaks occurred in the explanation group, and none in the stent-preservation group. Thirteen late deaths occurred in the explanation group, with a 5-year survival rate of 68%, and one late death (cancer) in the stent-preservation group, but the follow-up is significantly shorter. CONCLUSIONS: Leaving the mitral bioprosthetic stent and cuff intact eliminates the need for extensive dissection, thus shortening and simplifying the procedure and diminishing its attendant mortality and morbidity. It offers a safe and logical approach to replacement of a degenerated mitral bioprosthesis with a St. Jude valve of comparable size which projects into the left atrium, rather than a smaller one jammed into the orifice of the bioprosthetic stent.