Current status of porcine heterograft prostheses: a 5-year appraisal.

Between 1970 and 1975, 234 porcine heterograft valve prostheses were implanted in 193 patients with 12 operative (6%) and 21 late deaths (11%). Detailed hemodynamic studies were made 6 months to 1 year following operation in 72 patients. Mean atrioventricular (A-V) diastolic pressure gradients averaged 5.2 mm Hg for 29 mm heterografts and 2.3, 2.5, and 2.7 mm Hg for 31 mm, 33 mm, and 35 mm heterografts, respectively. In 10 patients with aortic prostheses peak systolic gradients averaged 16 mm Hg at rest (range 0-26) but increased to 70 mm Hg during exercise (range 20-125). Anticoagulants were not used except when intracardiac clot was present at operation. There were 12 systemic arterial emboli, all with mitral prostheses and low cardiac output; nine patients were in atrial fibrillation and three were in sinus rhythm. Three patients evidenced late tissue failure. Hydraulic function in the A-V position is excellent: prosthetic valve size is not limited by tertiary orifice and A-V anulus accepts large prosthesis. The patient's anulus is the determinant of aortic prosthesis size; heterograft internal diameter to outside diameter ratio is suboptimal and hydraulic function of the aortic prosthesis is marginal. In our clinical practice we consider the performance characteristics of currently available valves in relation to the individual patient's priorities to select an appropriate prosthesis.