Acute Effects of Liver Vein Occlusion by Stent-Graft Placed in Transjugular Intrahepatic Portosystemic Shunt Channel: An Experimental Study

Abstract

The purpose of this study was to evaluate the effects of hepatic vein occlusion by stent-graft used in transjugular intrahepatic portosystemic shunt (TIPS). The experiments were performed in six healthy pigs under general anesthesia. Following percutaneous transhepatic implantation of a porta-cath in the right hepatic vein, TIPS was created with a stent-graft (Viatorr; W L Gore, Flagstaff, AZ, USA). The outflow from the hepatic vein, blocked by the stent-graft was documented by injection of contrast medium and repeated injections of 99 Tc m -labeled human serum albumin through the port-a-cath. After 2 weeks, the outflow was reevaluated, the pigs were sacrificed, and histopathologic examination of the liver was performed. Occlusion of the hepatic vein by a stent-graft had a short and temporary effect on the outflow. Histopathological examination from the affected liver segment showed no divergent pattern. Stentgrafts used in TIPS block the outflow from the liver vein, but do not have a prolonged circulatory effect and do not affect the liver parenchyma.Key words: Portal hypertension-Transjugular intrahepatic portosystemic shunt-Stent-graft-Hepatic vein occlusion Over the last 10 years, transjugular intrahepatic portosystematic shunt (TIPS) procedures have almost completely replaced surgical portosystemic shunts in treatment of patients with portal hypertension and repeated bleeding from gastroesophageal varices [1][2][3][4][5] or refractory ascites. Longterm results of TIPS are, however, unsatisfactory due to the development of pseudointimal hyperplasia in the shunt channel and/or intimal hyperplasia in the adjacent hepatic vein [6].To overcome these problems, stent-grafts have been used [7][8][9][10][11][12]. These stent-grafts separate the shunt channel from the liver tissue, bile ducts, and the wall of the hepatic vein, preventing development of hyperplasia.Following TIPS, blood from the portal vein passes through the created shunt toward the right atrium, whereas flow to the intrahepatic portal vein branches is substantially decreased [13]. The cranial portion used for the TIPS stentgraft might block the outflow from the hepatic vein to which the shunt extends. A decrease in the hepatic arterial flow to the liver segment drained by the blocked liver vein was reported [14] as well as segmental liver ischemia [15]. Patients treated with a TIPS often have an impaired liver function. Reduced blood flow through one liver segment can cause further deterioration.The present study was performed in order to evaluate if the outflow from the hepatic vein blocked by a stent-graft, causing a ''pseudo-Budd-Chiari-syndrome,'' changed over 2 weeks of time and if there were any possible consequences for the affected liver segment. Materials and Methods Animals and AnesthesiaSix healthy pigs, 36-40 kg body weight, were used for the experiments after approval from the local ethics committee for animal research. All procedures were performed under general anesthesia, induced by intramuscular injection of 2 mg/kg azapCorr...