Thrombosis and degeneration of Hancock valves: clinical and pathological findings.

Of 415 Hancock valves implanted in 370 patients, 26 valve specimens were recovered at postmortem examination and 8 at reoperation. In 9 of these 34, thrombosis had formed without apparent alteration of the heterograft tissue (Group A). All were mitral prostheses, and the thrombi were attached to the sewing ring. Six of the patients died in the early postoperative period following prolonged low cardiac output syndrome and coagulation disturbances. Three patients had late valve thrombosis 12 to 26 months after operation and were in chronic atrial fibrillation with a very large left atrium. Four valve specimens (Group B) demonstrated degenerative changes of the heterograft leaflets such as shrinkage, perforation, and calcification. The clinical courses and possible pathogenesis are discussed.