Pathology of antibiotic-treated human heart valve allografts.

Pathology of antibiotic-treated human heart valve allografts. Forty-two human heart valves treated with an antibiotic solution were examined by light and electron micro-scopy up to 168 weeks after grafting in aortic, mitral, and tricuspid positions. There was a progressive degeneration of donor cells and by 40 days both fibroblasts and endothelial cells had vanished, leaving grafts virtually acellular. However, host inflammatory cells, together with fibrin and erythrocytes, infiltrated some regions. After 12 weeks macrophages were present in these focal collections of cells and were associated with the removal of intracuspal fibrin and the disruption of cuspal collagen. Avascular intimal fibrous sheaths of host tissue tapered from the margins of all grafts after six weeks and extended as much as halfway out of the cusp leaflets of some with consequent cusp thickening. Slow, progressive replacement fibrosis occurred along the deep surface of grafts but calcification of donor arterial wall was not observed. There was little invasion of the graft by fibroblasts from the intimal sheaths although macrophages were common along the interface between them and the underlying graft. These changes were qualitatively similar to those following chemical sterilization although intracuspal macrophage activity was generally much less and intimal fibrous sheaths were more extensive. Heart valve allografts treated with antibiotic solution before placement have been found clinically to be superior to those sterilized chemically , and in particular they have a much lower incidence of cusp rupture. It is significant that leaflet failure has not so far been observed at Green Lane Hospital in antibiotic-treated aortic valve allografts regardless of site, although cusp rupture has occurred in 4-3% of antibiotic-treated pulmonary valve allografts placed in the mitral position. The clinical performance of untreated, chemically sterilized, and antibiotic-treated heart valve allografts in this series has been comprehensively reviewed elsewhere (This paper describes the histopathology of antibiotic-treated human heart valve allografts and compares these findings with earlier studies of the pathology of chemically treated allografts Forty-two heart valves which had been used as allo-grafts for from several hours to 168 weeks were examined. Sixteen were recovered when they were surgically replaced and 26 were recovered at necropsy following hospital death (22) or late death (4) from subdural haemorrhage, hepatitis or cardiac arrhythmia. Twenty-seven grafts were aortic valves used to replace aortic (18) or mitral (9) valves, and 15 were pulnonary valves used as grafts in the mitral (13) and tricuspid (2) positions. The allografts …