EXPERIMENTAL RIGHT VENTRICLE TO PULMONARY-ARTERY DISCONTINUITY - OUTCOME OF POLYURETHANE VALVED CONDUITS

Objective: The ideal substitute for the treatment of ventricle-pulmona ry artery discontinuity remains a topic of controversy, because of cal cifications and degeneration of biologic substitutes leading to subseq uent reoperations, Because polyurethane valves used in ventricular ass ist devices show a satisfactory biocompatibility, the aim of this stud y was to evaluate a valved conduit composed of a Dacron graft incorpor ating a trileaflet 25 mm polyurethane valve. Methods: The conduit was implanted between the right ventricle and the main pulmonary artery in adult sheep, with ligation of the proximal pulmonary artery. The anim als received no medications. Serial hemodynamic data were collected at the time of implantation and at postoperative intervals of 6 and 12 m onths. Results: The peak pressure gradient across the valve increased significantly between implantation (0.17 +/- 5.6 mm Hg) and 6 months a fter operation (7.3 +/- 3 mm Hg, p = 0.0007) and remained stable there after (6.7 +/- 3 mm Hg at 12 months), whereas the cardiac output remai ned unchanged (4.6 +/- 0.6 L/min at implantation, 4 +/- 0.6 L/min at 6 months, and 3.9 +/- 1.1 L/min at 12 months). At the completion of the study, valve samples were processed and vapor coated,vith carbon for microscopic examination. There was one instance of nonadherent thrombu s formation inside a cusp but no structural failures. The other valves , were free of calcium deposits and no significant amounts of phosphor us could be detected by scanning electron microscopy and energy disper sive spectrometry, Conclusions: These data demonstrate the good hemody namic performance, low thrombogenicity, and acceptable durability of t he polyurethane valves implanted in the right side of the heart in a c hronic sheep model.