One hundred and four patients with complex congenital heart disease were operated between 1966 and 1978 for reconstruction of the right ventricular outflow using an aortic homograft conduit. The average age was 14 years, ranging between 3 years and 28 years of age with an equal male/female ratio. Hospital mortality was 50% and there were 3 late deaths (6%) amongst the surviving 52 patients. Seventy-nine percent of the survivors are well and asymptomatic between 1 year and 12 years follow-up. Only 2 patients (4%) developed homograft conduit obstruction with a peak systolic gradient over 40 mmHg and 1 patient needed reoperation 9 years after the original primary reconstruction. Thirty-one patients underwent cardiac catheterization between 1 year and 9 years following the original operation, and a further 9 patients underwent a second cardiac catheterization at a mean of 36 months after their first cardiac catheterization. Ninety-three percent of these 31 patients had a resting peak systolic gradient across the homograft conduit of between 0 and 55 mmHg (mean 14.16 +/- 14.03). Calcification in the wall of the aortic homograft appeared within the first 2 years in about 80% of the patients but this had no correlation to the gradient across the homograft, nor did it interfere with the valve performance.

Three forms of discrete sub-aortic stenosis have been recognised and described. A long tunnel-like narrowing of the left ventricular outflow tract was the most severe form and was recognized as different from hypertrophic obstruction cardiomyopathy (HOCM). Sixty patients with discrete sub-aortic stenosis have been operated on with enucleation of the stenosis during the past 15 years at the National Heart Hospital, London, and followed-up for up to 14 years. Overall there were 4 hospital deaths (6.6%) and only one late death. Emphasis has been placed on the superiority of blunt dissection in the enucleation of the entire, discrete stenosis when contrasted with the conventional sharp dissection technique which may well lead to subsequent accretions of obstructive thickening. The surgical enucleation of the discrete sub-aortic stenosis has been an entirely satisfactory procedure from a hemodynamic viewpoint and carries a low operative risk with every possibility of a subsequent event-free follow-up.