COMPOSITE AND PLAIN TUBULAR SYNTHETIC GRAFT CONDUITS IN RIGHT VENTRICLE-PULMONARY ARTERY POSITION - FATE IN GROWING LAMBS

Our goal was to identify the most appropriate material for right ventr icle-pulmonary artery conduits in growing animals. We used 100 lambs t hat were 3 to 4 weeks old (mean weight 11.7 kg), Follow-up was up to 2 4 months. Group I received plain tubular conduits: (1) Dacron knitted fabric, (2) collagen-coated knitted fabric, (3) Milliknit and Microkni t material, (4) woven Dacron fabric, (5) three-dimensional Dacron fabr ic (crossweave 500 and 800), or (6) polytetrafluoroethylene. Group II received either a (1) woven Dacron fabric conduit with a built-in tiss ue valve or (2) polytetrafluoroethylene graft with a built-in St. Jude Medical valve. We did angiograms and catheterizations every 3 to 6 mo nths and killed the lambs at 6, 12, 18, or 24 months. Tubular Dacron f abric woven or knitted grafts, regardless of matrix, pore size, thickn ess, or coating, caused formation of a thick acellular pseudointima bu ildup, which led to progressive obstruction starting as early as 3 mon ths. Polytetrafluoroethylene grafts in groups I and II showed the form ation of thin inner and outer capsules (0.5 mm) and none developed obs truction despite wall calcification. Conduits of woven Dacron fabric w ith a built-in tissue valve degenerated rapidly, leading to calcificat ion thrombosis and obstruction within 3 months; no lamb survived 12 mo nths, Polytetrafluoroethylene conduits with a St. Jude Medical valve i n lambs receiving anticoagulants remained free of obstruction and cont inued to function well. It appears that synthetic conduits of polytetr afluoroethylene perform well in either of the situations here tested a nd may be the best choice at present.