The Pathology of Pulmonary and Aortic Valve Allografts Used as Mitral Valve Replacements in Dogs

Abstract

Thirty aortic and 30 pulmonary valves were mounted on stents following storage in Hanks balanced salt solution with or without the addition of antibiotics. These were then used as allografts to replace the mitral valve in dogs. Thirteen dogs with pulmonary valve grafts and 9 with aortic valve grafts died or were sacrificed for reasons unrelated to the allografts per se. All the 17 remaining pulmonary valve grafts failed because of obstruction by vegetations (47%) or central incompetence due to cusp rupture (29.5%) or cusp shrinkage (23.5%). With the 21 comparable aortic valve grafts, 59.1 % developed endocarditis but the remaining 40.9% of the animals had competent allograft valves when they were killed after 94-522 days. Organizing granulation tissue progressively replaced much of the donor arterial wall and sometimes merged with the intimal fibrous sheaths which tapered from the graft margins toward or onto the base of the valve cusps. These sheaths were a discrete layer in antibiotic-treated valves, bu...