Valve-containing conduits have made possible the repair of many congenital anomalies that involve right ventricular-pulmonary arterial discontinuity. The distressing problem of neointimal peel formation with eventual conduit obstruction in patients with
Dacron valved conduits has led to the need for premature replacement in many patients. Externally stented polytetrafluorethylene has demonstrated superior patency in the venous system experimentally and clinically and was believed to have potential advantages over
Dacron for conduit construction. This study compares the transconduit resistance and the thickness of the neointimal peel in right ventricular-pulmonary arterial conduits constructed of externally stented
polytetrafluoroethylene with those of woven
Dacron. The 19 mm externally stented
polytetrafluoroethylene conduits (
Impra, Inc.) containing a Hancock porcine valve (Extracorporeal Inc.) were implanted in six adult mongrel dogs followed by proximal occlusion of the pulmonary artery. In six additional animals, a
Dacron valved conduit of similar size and length was inserted. Cardiac output, transconduit gradient, and resistance were measured at operation and at 3 months. All conduits were subsequently explanted, opened longitudinally, and the thickness of the neointimal peel (excluding
suture lines) measured. No hemodynamic differences were noted during the 3 month follow-up. However, the thickness of the neointimal peel was fourfold greater in
Dacron conduits (609 +/- 144 mu) than in the conduits constructed of externally stented
polytetrafluoroethylene (156 +/- 50 mu) (p less than 0.01). The thick peel in
Dacron conduits extended into the outflow portion of the porcine valve cusps and prevented their full excision. The
neointima in externally stented
polytetrafluoroethylene conduits was thin and uniform and did not extend onto the leaflets or limit their mobility. This study demonstrated that the early hemodynamic performance of externally stented
polytetrafluoroethylene conduits was comparable to that of
Dacron conduits;
Dacron conduits were subject to an accelerated rate of peel formation that affected leaflet mobility and may be
a factor in early valve degeneration; a thin
neointima formed in externally stented
polytetrafluoroethylene conduits and valve leaflet motion was preserved. This study showed that externally stented
polytetrafluoroethylene conduits offer advantages over
Dacron valved conduits and warrant clinical application.