THE EFFECTS OF RETROGRADE PORTAL VENOUS FLOW FOLLOWING SIDE-TO-SIDE PORTACAVAL ANASTOMOSIS: A COMPARISON WITH END-TO-SIDE SHUNTS*

Abstract

Hemodynamic and metabolic studies were performed on 13 dogs following side-to-side portacaval anastomosis. Directional flow data indicated the proximal portal vein no longer carried blood toward the liver but served as an outflow vessel. Available evidence indicates that hepatic arterial inflow communicates extensively with portal venous blood by presinusoidal and intralobular anastomosis; following a side-to-side shunt these vessels afford a low resistance pathway to the inferior vena cava which bypasses the hepatic vein. An arterio-portal venous oxygen difference (3.30 vols.%) and sulfobromophthalein extraction (14%) indicated some hepatic cell perfusion. In no instance was the evidence of metabolic efficiency as great in the portal vein as it was in the hepatic vein (9.10 vols.% and 29% respectively). Moreover, it appeared that retrograde flow out the portal vein occurred at the expense of adequate perfusion of the center of the liver lobule. This results in central lobular ischemia, which was felt to be responsible for the lower sulfobromophthalein clearance, greater anemia and poorer survival in side-to-side shunts when compared with end-to-side anastomosis.