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.