Prospective study of a prosthetic H-graft portacaval shunt. This study was undertaken to prospectively evaluate the 8-mm Gore-Tex interposition H-graft portacaval shunt. Thirty-six high-risk patients at the University of South Florida-affiliated hospitals received small-diameter shunts because of bleeding esophagogastric varices over a recent 2-year period. Portal vein and portal vein-inferior vena cava gradients were significantly reduced after shunting. These pressure changes were manifested clinically by the absence of variceal rebleeding and improvement of ascites; in addition, the incidence of encephalopathy was low. The 8-mm graft maintained hepatopedal flow in 67% of the patients, but reversal of flow did not result in complications commonly associated with poor portal perfusion. Graft thrombosis occurred in four (11%) patients. All grafts were successfully revised, three by operative revision and one by an interventional radiologist. Operative mortality was low (11%), and morbidity was unusual. The small-diameter H-graft portacaval shunt is a safe and effective method of treatment for bleeding esophagogastric varices. 