Homograft replacement of the aortic valve. A clinical and pathologic study.

Abstract The results are described of replacement of the diseased aortic valve in 91 patients by a chemically sterilized and freeze-dried homograft. The cases are the Guy's Hospital complement of a total series of 250 such operations performed by one of us (D.N.R.) since July 1962. The total mortality in the first 31 cases was 22 (71 per cent), and in the last 60 cases, after a radical change in operative technic, was 9 (15 per cent). In only one of the latter was death due to malfunction of the valve. Forty-two of this second group were in clinically ‘excellent’ condition at 3 months after operation. Of 37 of the patients so classed at 3 months, 33 were unchanged when followed up at one to four and one-half years after operation. Those grafts later examined histologically, while firmly attached to the host by direct fibrous union and intimal fibrous sheaths, remained substantially acellular and unorganized. Some cusps had severe “degeneration” of their connective tissue, and others were found to be ruptured or perforated. Calcification was present in one or more homograft cusps of 4 patients who died from aortic regurgitation 14, 42, 44 and 52 months, respectively, after operation, and in a fifth, whose graft was excised after 43 months. In 2 of these patients, 1 of whom had survived bacterial endocarditis, calcification was sufficient to interfere with function. At this writing, calcification has been found only in hemodynamically abnormal valves. Systolic gradients of 15 to 35 mm. Hg across the homograft valve have been found postoperatively in 5 of 13 patients. Evidence of spontaneous systemic embolism was found in 3 patients. Anticoagulant drugs were given to 1 only. One case was complicated by bacterial endocarditis. Two fatal cases of fungal endocarditis occurred in early patients receiving corticosteroid drugs. Postoperative heart block was not encountered. Antibodies to myocardium were found transiently in the serum of several patients who had received aortic valve homografts but also in comparable or greater proportions of those who had undergone other cardiac operations. Other tests for circulating antibodies against graft components, or for lymphocytes sensitized to them, proved negative. The chemically sterilized freeze-dried homograft has certain clear advantages over the prosthetic aortic valve, but there is doubt as to its ultimate fate. For this reason we attach great importance to comparative trials of different methods of preparing and storing homografts. Relevant published data are reviewed. Secure insertion of a well fitting homograft is considered to be of the first importance. In favorable circumstances such valves have maintained good function for over four years. There is good reason to suppose that improved methods of selection, preparation and storage will lengthen their effective life.