The technique of preparing prosthetic aortic heterologous valves for clinical use is outlined in detail, and the surgical implantation of these grafts into the mitral, aortic, and tricuspid areas is described. Between February and December 1967, 42 such grafts have been inserted into 41 patients with good results up to 10 months since the operation. No systemic emboli have occurred although anticoagulants have not been used for more than four to six weeks postoperatively. The possibility of replacing heart valves with reconstructed heterografts has recently been demonstrated (Ionescu, Wooler, Smith, and Grimshaw, 1967; Ionescu, Stoker, and Wooler, 1968; Wooler and Ionescu, 1968). In Leeds, altogether 42 prosthetic heterologous aortic valves have be.n inserted into 41 patients between February and December 1967. The immediate and short-term results are encouraging. The details of clinical use and the results in patients operated upon have been reported (Ionescu, 1968; Ionescu, Wooler, Grimshaw, and Smith, 1968; Wooler and Ionescu, 1967a, b, and c). Replacement of the mitral valve with a prosthetic aortic heterograft has proved to be a simple surgical procedure, and so we have used the same technique for the aortic and tricuspid valves. The purpose of this paper is to outline step by step the technique of preparation and surgical implantation of prosthetic aortic heterografts when replacing the mitral, aortic, and tricuspid human valves. PREPARATION OF THE GRAFTS COLLECTION AND DISSECTION OF THE VALVES The aortic valves are taken from pigs 1 to 2 years old and weighing between 150 and 300 kg. The hearts are collected without sterile precautions immediately after slaughter and are brought to the laboratory. The 1Commercially available from Hypodermic Services, 45 Hare Park Lane, Hightown, Liveredae, Yorks
