Model of complete separation of the hepatic veins from the systemic venoussystem

Background. In patients undergoing a Fontan operation, partial diversion of the hepatic veins to the pulmonary venous atrium has been tried with vario us techniques. They failed because of the development of intrahepatic colla terals leading to an unacceptable right-to-left shunting. We postulate that to avoid the formation of intrahepatic collaterals, the totality of the li ver has to be drained into the same pressure compartment. We have designed a model of cavopulmonary anastomosis in which a prosthetic conduit reproduc es an azygos continuation, associated with the diversion of the totality of the hepatic venous return. This article reports on the early hemodynamics and the fate of the separation of the two venous compartments in long-term survivors. Methods. Eighteen goats were operated on; the pulmonary artery and hepatic vein pressures were recorded. During month 2, an opacification of the infer ior,vena cava and the cavopulmonary connection was performed. Between month s 6 and 14, another opacification was performed, together with pressure rec ording at both ends of the conduit. Results. Postoperatively the pulmonary artery pressure was pulsatile with a mean of 10 mm Hg and the hepatic vein pressure was 0 mm Hg. The first angi ogram showed patent tubes with fast progression of the contrast. Throughout the inferior vena cava injection, there was no opacification of the portal or hepatic veins. The late study showed a narrowed conduit in all animals. During the injection, a collateral was injected, feeding into the inferior mesenteric vein. No collateral circulation could be seen draining directly into the liver. The median gradient between the two ends of the conduit wa s II mm Hg. Conclusions. The isolation of the entire hepatic venous drainage is feasibl e and efficient for the separation of two pressure compartments. No intrahe patic collaterals are observed with this model at short- or long-term follo wup. The separation of the hepatic venous drainage should persist without c ollateral circulation as long as the inferior vena cava pressure stays at t he levels observed in Fontan circulation. (Ann Thorac Surg 2000;70:2096-101 ) (C) 2000 by The Society of Thoracic Surgeons.