ENLARGEMENT OF THE RIGHT-VENTRICULAR OUTFLOW TRACT AND THE PULMONARY-ARTERY WITH A NEW BIODEGRADABLE PATCH IN TRANSANNULAR POSITION

Absorbable, nonwoven patches made from polyhydroxybutyrate (PHB) were implanted as transannular patches into the right ventricular outflow tract and pulmonary artery in 13 weanling sheep, the test group. Six sheep, in which a transannular Dacron patch was implanted, served as control group. The test and the control patches were harvested 3-24 months later. The results were documented macroscopically, by histological examination, and by scanning electron microscopy. The 6-keto-PGF(1 alpha) activity was measured in the regenerated tissue and compared with that in the native pulmonary artery. No aneurysms were noted. Regeneration of a neointima and a neomedia, comparable to native arterial tissue, was observed in the test group. In the control group, a neointimal layer was present but no neomedia comparable to native arterial tissue. Scanning electron microscopy disclosed differences in the endothelial structure between the test and control groups. 6-keto-PGF(1 alpha) activity was present in both the test and control groups. It is concluded that absorbable, nonwoven patches of PHB can be used as a scaffold for tissue regeneration in low-pressure systems. The regenerated vessel had structural and biochemical qualities in common with the native pulmonary artery.