Direct intrahepatic portocaval shunt through transhepatic puncture via retrohepatic inferior vena cava: applied anatomical study.

Background: DIPS is to create a portosystemic shunt directly between the portal vein and the retrohepatic inferior vena cava (RIVC) without passing through the hepatic vein. It has been recommended that the DIPS could be applied when routine TIPS is unsuccessful or the patient has anatomical variations of the hepatic vein. The aim of this study was to identify the safe area of the RIVC where the DIPS can be safely established.

Materials And Methods: The lengths of the safe and unsafe areas of the RIVC were measured. The tributaries of the RIVC were examined. The diameter of these tributaries was measured and their incidence and relation to the safe area of the RIVC were observed. The puncture distances of DIPS and TIPS were measured and compared.

Results: The liver together with the RIVC was collected from 31 adult cadavers (age 32-65 years; M/F 25/6). 1. The safe and unsafe areas of the RIVC: the total length of the RIVC was 70.1 +/- 13.0 mm (33.1-92.0 mm), whereas the length of the safe area of the RIVC was 54.3 +/- 12.3 mm (20.2-71.1 mm), which was about over 70% of the total length. The length of the unsafe area at the upper end was 5.9 +/- 1.8 mm (3.0-10.2 mm), and at the lower end was 8.9 +/- 2.9 mm (3.1-20.0 mm). 2. The tributaries of the RIVC: In about 90% of the cadavers (90.3%; 28 out of 31), the LHV and MHV had the common trunk. The other three cadavers (9.7%; 3 out of 31) had independent RHV, MHV and LHV. There were 217 of small hepatic veins draining into the lower segment of the RIVC. Over 70% of the small hepatic veins were smaller than 5 mm in diameter and distributed on the anterior and left wall of the lower RIVC. 3. Puncture distances of the DIPS and TIPS: The distances from the bifurcation of the portal vein to the RIVC, to the right and to middle hepatic veins were 31.2 +/- 7.9 mm (15.0-47.2 mm), 38.6 +/- 8.1 mm (17.2-59.0 mm), and 46.6 +/- 8.2 mm (34.0-68.1 mm), respectively. Thus, the puncture distances via the RIVC, RHV and LHV were significantly different (P < 0.001). The puncture distance of the DIPS was shortest.

Conclusion: Anatomically, DIPS is a feasible interventional procedure to make a intrahepatic shunt between IVC and portal vein directly, and has its anatomical advantages compared to TIPS.