Pulmonary site bioprostheses: morphologic findings in 40 cases.

CONTEXT: From January 1995 to June 2003, there were 514 patients who underwent pulmonary valve replacements at either the Hospital for Sick Children or Toronto General Hospital. Fifty-four (10.5%) of these adults returned for replacement of their prostheses because of failure. Forty (74.1%) of the 54 explants were bioprostheses, and 14 (25.9%) were homografts. OBJECTIVE: To present the morphologic findings from this consecutive series of 40 pulmonary-site bioprostheses. DESIGN: Data were obtained by review of pathologic, clinical, and surgical records for all 40 patients with bioprosthetic pulmonary valves explanted from 1995 to June of 2003. RESULTS: The mean duration of valve implantation was 14.3 +/- 5.2 years (2-26 years). Median age at implantation was 16.7 +/- 10.3 years (range, 3 months to 53 years). Structural valve deterioration was found in 39 (97.5%) of the valves. Morphologic evidence of stenosis was found in all valves, whereas incompetence was found in 28 (70.0%). Calcification was present in 32 (80.0%) of the valves and was severe and diffuse in 22 (55.0%). Host tissue overgrowth, or pannus, was present on 39 (97.5%) of the valves and was severe in 35 (87.5%). Tears were present in 19 (47.5%) of the valves. CONCLUSIONS: Explanted bioprostheses showed a high degree of calcification and pannus, which together led to stenosis. Cusp immobilization, involving all 3 cusps, was frequent and was more common in patients younger than 30 years of age at explantation (P < .001). Host-tissue overgrowth is a significant problem with bioprostheses, and pulmonary-site bioprostheses are no exception.