Direct Portacaval Shunt Experimental And Clinical Studies

Part One: Direct intrahepatic portacaval shunt: the experimental studyPurpose: To determine the safety and feasibility of creating direct intrahepatic portacaval shunt (DIPS) in swine with puncture under transcutaneous ultrasound guidance. Material and Methods: DIPS was created in swine by puncturing intrahepaic portal vein through retrohepatic segment of inferior vena cava (RHSIVC) guided by transcutaneous ultrasound. Liver function, serum NH3 level and portosystemic pressure gradient of swine were compared before and after DIPS. Patency of shunt was followed by portography every 7 days after procedure. When the shunt totally occluded which confirmed by portography or at the end of experiment swine was sacrificed and the shunts with surrounding liver tissue were excised for gross and histological examination.Results: DIPS was successfully established in 10 animals without any complications. 3.70±1.25 (2~5) passes were required to accomplish puncturing from RHSIVC to portal vein. Mean distance of puncture and the angle between the axial of stent and RHSIVC were 17.13±3.18mm (11.3~21.0mm) and 30.68±2.57°(22°~34.1°) respectively. The portosystemic pressure gradient of swine was decreased from 4.00±0.94mmHg before DIPS to 1.50±0.74mmHg after procedure (P=0.001). After DIPS, animal's alanine aminotransferase (ALT) and aspartate aminotransferase (AST) became significantly higher than the pre-DIPS values transiently. 14 days after procedure the ALT and AST returned to their normal pre-DIPS level. Animal's total bilirubin (TB) and combined bilirubin (CB) remained unchanged before and after DIPS. Swine' serum NH3 level increased significantly 1 day after procedure and returned to its baseline value at the 7th day after DIPS. 10 DIPS shunts kept patent 7 to 28 days (median patent time was 14 days). Patency rates in 7, 14, 21, and 28 days were 80%, 50%, 20% and 10% respectively. 90% shunt occulded when swine was sacrified. Gross and histological examination of excised shunt specimen showed that the incidience of occlusion occurred in the parenchymal portion, IVC-end and portal venous end of stent was 100%, 33.3% and 11.1% respectively. Intraluminal thrombosis, ingrowgh of the proliferating pseudointima and liver tissue through the mesh of stent were 100%, 66.7% and 44.4% respectively for the occlusion of the shunt.Conclusions: Our initial experience demonstrated that it was safe and feasible to establish a direct intrahepatic portacaval shunt by puncturing into intrahepatic portal vein through retrohepatic segment of IVC guided by transcutaneous ultrasound in swine. Further studies seemed to be necessary for application of DIPS in cirrhotic patients.