Anatomic Considerations Related to the TIPS Procedure

Abstract

Learning objectives: As a result of attending this plenary session, the attendee will be able to (1) Identify the technique-related complications oftransjugular intrahepatic portosystemic shunt (7IPS),. (2) identify the anatomic-dependent complications of TIPS,. (3) understand the anatomic landmarks necessary to successfully perform TIPS,. and (4) correctly understand the steps necessary to avoid complications when peljorming TIPS. THE creation of a TIPS is a recent development in the treatment of portal hypertension 0). In this procedure, the portal vein is decompressed by creating an artificial communication between one of the hepatic veins and the portal vein with a metallic stent mesh. Multiple reports suggest that the TIPS procedure is an effective, safe, reliable, and repeatable technique 0-13). However, as more experience was gained with the procedure, several anatomicand technique-related complications were reported that increased the difficulties in placing and maintaining the shunt 00,14-22). Technique-related complications include shunt occlusion, extraparenchymal puncture, creation of an intraperitoneal shunt, intraperitoneal bleeding, liver capsule perforation by the transjugular needle, misplacement and migration of the stent, and cardiac perforation 04-22). Anatomic-dependent complications are related primarily to traversing a hepatic arterial or venous branch or biliary radicle during parenchymal puncture and stent placement. In addition, failure to gain transjugular access, to find an adequate hepatic vein for puncture, or failure to perform the puncture of the portal vein due to an anatomic variation 04-23) complicates the performance of the TIPS procedure. Knowledge of the vascular and biliary liver anatomic structures is imperative to perform the TIPS procedure safely. The most common anatomic variations of the hepatic veins and portal vein, and the relation between the different structures of the portal triad must be mastered before attempting the procedure (24). The anatomic basis for performing the TIPS procedure is the assumption that the right hepatic vein (RHV) is located superior and posterior to the portal vein bifurcation. As the RHV courses along the right hepatic fissure, it receives branches from segments V and VIII anteriorly and segments VI and VII posteriorly. In the periphery of the liver, the RHV is located along the right fissure of the liver in a path between the anterior and posterior branches of the right portal trunk, whereas more centrally the ostium and the final few centimeters of the RHV are cranial and dorsal to the bifurcation of the portal vein and the right portal trunk. The transparenchymal puncture made to create the intrahepatic shunt is, therefore, performed from the more central portion of the RHV in a caudal and anterior (or medial) direction. The portal vein is punctured along the right portal trunk at the portal bifurcation or, less frequently, at the proximal left portal trunk. Alternatively, the portal vein may be approached from the middle hepatic vein (MHV) or left hepatic vein (LHV). In that case, the direction of the transparenchymal puncture must be posterior for the MHV and posteromedial for the LHV (24). Liver casts of 25 healthy liver specimens were injected with acrylic material into the vascular elements and bile duct at the hepatic pedicle. After corrosion with sodium hydroxide, the specimens were washed thoroughly to remove organic material. The anatomy of the RHV, MHV, and LHV; the position of the main portal vein bifurcation; the distance between the RHV, MHV, LHV and the portal bifurcation; the anatomy of the portal bifurcation; and the relation of the structures of the portal triad at the portal bifurcation and the proximal right and left portal trunks were reviewed (24).