Prosthetic valve endocarditis. A clinicopathological study of 31 cases

Prosthetic valve infective endocarditis was found in 31 out of 275 autopsies on patients with valvular prostheses. Mean postoperative survival was 332 days. Thirty patients had mechanical valves and only 1 had an infected tissue valve. The commonest pathogens were staphylococci, followed by Gram-negative bacilli and fungi. In all the patients with mechanical valves the infection was situated at the host-prosthesis sewing ring interface, and most also had vegetations on the prosthetic struts or cage. The infected tissue valve had vegetations on the prosthetic cusps only. Ring abscesses were present in one-third of cases and had destroyed the bundle of His in 1 patient. Clinically recognized pre-operative infective endocarditis was present in only 3 out of the 31 patients. Seven of the 31 patients died because of malfunction of the prosthesis, 10 died of systemic embolism, 4 of ruptured mycotic aneurysms, and the remaining 10 of other causes including myocardial failure, pyaemic abscesses and toxaemia.