Risk factors for early degeneration of allografts in pulmonary circulation

The aim of this study was to define risk factors for early degeneration of allografts in pulmonary circulation and to recommend some guidelines to minimize them.

Between January 1988 and March 1995, 202 patients with various types of congenital heart disease received cryopreserved allograft conduits for reconstruction of their right ventricular outflow tract. We report on 63 patients receiving allografts ranging from 9-24 mm size within the first 2 years of life.

Survivors have been followed for 4-67 months. Survival at 5 years, including hospital mortality, was 66%. Two patients died at reoperation. Of the patients 19.6% (9/46) had early structural deterioration (SD) of their vascular allografts at a mean of 15.2 months after implantation. Seven of these have already been reoperated with allograft exchange. Freedom of reoperation was 66% at 5 years. Infants showed 48% freedom of reoperation at 5 years compared to 90% in the 1-2 years age group, while freedom of SD was 59% in infants at 48 months compared to 87% in the 1-2 years age group. Of allografts with SD in the infant group 66% had an allograft size of < 14 mm. In aortic allografts freedom of SD was 62% compared to 93% in pulmonary allografts. Freedom of allograft wall calcification was 46% at 18 months in all patients. In the statistical analysis, only infant age (P = 0.03) and aortic allograft (P = 0.02) were shown to be significant risk factors for early SD.

The use of pulmonary allografts, avoidance of relatively short and small conduits of < 14 mm in diameter, might improve the durability of allografts in infants and small children.