Pathology of antibiotic-treated human heart valve allografts

Gavin, J. B., Herdson, P. B., Monro, J. L., and Barratt-Boyes, B. G. (1973).Thorax, 28, 473-481. Pathology of antibiotic-treated human heart valve allografts. Forty-two human heart valves treated with an antibiotic solution were examined by light and electron microscopy 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 half-way 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.