The Clinical Application And Anatomy Of Percutaneous Direct Intrahepatic Portacaval Shunt

[Background] Since Rosch firstly carried through the experimental research of transjugular intrahepatic portacaval shunt in 1969, TIPS has been one of the major interventional treatment to portal hypertension. But TIPS is disadvantageous in that it's hard to keep the shunt permanently unobstructed. Researches have revealed that the incidence of severe stricture or obstruction within 6 or 12 months was respectively 17% -50% and 23%-87% and about 75% stenosis occurs in the draining veins of TIPS—the hepatic veins. This, in turn, has dramatically affected the long-term curative effects of TIPS and confined its further development and application . So TIPS has been considered only as a temporary portal decompression. Inferior vena cava is the largest vein in human body , wider than the hepatic vein, so some researchers propose direct intrahepatic portacaval shunt to lead some portal blood flow directly into vena cava, hoping to obtain more stable bypass. As DIPS establishes shunt between intrahepatic portal vein and the thick retrohepatic segment of inferior vena cava, which makes interventional portal shunt possible for patients difficult to undergo TIPS, it becomes a hot spot. Peterson reported 40 cases of IVUS-guided DIPS in 2001. Follow-up results of them during 8-38 months were satisfactory: portal vein pressure dropped from 16mmHg～38mmHg before operation to 9mmHg～24mmHg after operation with an average decrease of 10mmHg while hemorrhage control rate incresed to as high as 80% and as much as 74% ascites. Subsided. Although there was no obvious difference between the short-term effects of DIPS and TIPS, yet in the long run, there was a far lower incidence of stricture and obstruction of shunted veins for DIPS. Quinn's report showed 60% of the shunts were unobstructed within a year and in Petersen's report 100% were unblocked within 6 months and 75% within a year. DIPS operations were IVUS-guided portal venocentesis via RHSIVC in Petersen's reaport. But in our country most cirrhotic patients have suffered hepatitis so it's harder to puncture their livers than those of alcoholic cirrhotic patients. What's more, centesis on the convergence of hepatic veins and inferior vena cava via RHSIVC not only leads to heart stent into the right atria owing to the high centesis position and affects later liver transplant but also is expensive. So this project aims to expolre the feasibility and security of CD(color Doppler)-guided DIPS operations by percutaneous direct portal venocentesis to retrohepatic segment of inferior vena cava, which is simple, accurate and cheap.[Objective] This project is directed at exploring the feasibility and security of DIPS operations through anatomic study on adult liver specimens and radiological study on cirrhotic patients; the feasibility and security of CD(color Doppler)-guided DIPS operations by percutaneous direct portal venocentesis to retrohepatic segment of inferior vena cava and evaluate its preliminary clinical effects.[Methods] (1) 30 formaldehyde-fixed adult livers are stripped off bluntly from the diaphragmatic and splanchnic surface respectively to expose clearly the right and left branch of portal vein and retrohepatic segment of inferior vena cava to measure the diameter and pathway of the right and left branch of portal vein, their proximal distance to the retrohepatic segment of inferior vena cava(the nearest two points can be perceived as punture points), the diameter, length of the retrohepatic segment of inferior vena cava and the radius of liver parenchyma. (2) 30 chronic cirrhotic patients were randomly selected to undergo 2 or 3 dimentional multiple color Doppler, CT or MRI screening to measure the size, shape, resonance of the liver; the inner diameter, pathway and velocity of flow of the right and left branch of portal vein; the diameter, length of RHSIVC and the radius of liver parenchyma; the nearest distance from the right and left branch of portal vein to RHSIVC respectively. (3) 2 patients of hepatocirrhosis accompanied with ascites or massive hemorrhage of the the alimentary canal were selected to undergo CD(color Doppler)-guided DIPS operations. Comparison concerning the number of erythrocytes, the volume of hemoglobins, the function of liver, the change of blood ammonia level and portal venous pressure, the decrease of ascites volume was made before and after the operation. Color Doppler ultrasonography was also employed in the follow-up to examine the shunt and evaluate the the long-term and short-term clinical effects of DIPS.[Results] (1) The form of caudate lobe of the liver enclosing the retrohepatic segment of inferior vena cava:"C"shape accounted for 56%(17 cases) while"U"shape and"O"shape were 37%(11cases) and 6.6%( 2 cases) respectively. The length and outer diameter of RHSIVC were 39.79±6.71 mm and 26.63±4.51 mm. The length, midpoint outer diameter of the left branch of portal vein and the distance from its midpoint to the front wall of RHSIVC were 33.97±5.88 mm,10.40±1.8 mm,24.80±7.79 mm. The length, midpoint outer diameter of the right branch of portal vein and the distance from its midpoint to the front wall of RHSIVC were 23.58±6.10 mm,9.77±2.01 mm,18.49±5.57 mm. The thickness of the caudate lobe of the liver between front wall of the inferior vena cava and the right branch of portal vein was 12.0±4.68 mm. The angle from the vertical midpoint axis of inferior vena cava to the right and left branches was 30～45°.(2) Measured by color Doppler sonograoghy, CT and MRI, the lengths of RHSIVC were 66.88±13.55mm,65.31±12.61 mm,68.11±14.80 mm,which is statistically insignifican(tp>0.05). Similarily the lengths of RHSIVC enclosed by liver parenchyma were 14.71±7.55mm,14.31±6.61 mm,14.98±7.90 mm(p>0.05), the distance from the right branch of intrahepatic portal vein to the portal branch and to RHSIVC were 24.58±6.66 mm,25.45±8.16 mm,27.10±8.66 mm(p>0.05). All these figures show no statistic importance. (3)Recent outcomes of DIPS operations: Both 2 cases succeeded with an average time of 1.5h and there were no complications resulted from incorrect operation skill. The success rate was 100%. Portal venography showed no stenosis or obstruction in shunts and intrahepatic portal vein branches. Esophageal varices bleeding was effectively controlled and difficult ascites subsided or disappeared. Symptoms of splenomegaly and hypersplenism were obviously relieved. Relevant laboratory detections revealed distinct redintegration of platelets, common serous bilirubin, serous protein, PT and SGPT. Intrahepatic hemodynamic examinations performed by 7 D color Doppler showed there was no sign of rush blood flow and the speed of blood flow in the shunts was faster than in those of transhepatic venous TIPS operations. Barium meal examination of the upper alimentary tract showed Esophageal varices bleeding was fundamentally cured with continous mucous rugae though sectional esophageal wall was still loose. DIPS follow-up results: Both two patients were strictly followed up with monthly color Doppler ultrosonography, barium meal examination of the upper alimentary tract and routin laboratory detection. Till now, there is no stenosis resulting from the hyperplasia of pseudointima in the shunts as well as on both sides of the stents; Child-Pugh grade is improved averagely to B in three months after the operation. Results of different stages of follow-up are constant and there are no realpases of clinical complications of portal vein hypertension .[Conclusion] (1)The anatomic study of liver specimens reveals that retrohepatic segment of inferior vena cava and RHSIVC enclosed by liver parenchyma are comparatively long so it's safe and feasible to perform DIPS operation. (2) Color Doppler Sonography, CT and MRI can all clearly reveal the anatomy of RHSIVC and the portal vein. The average length of RHSIVC is 60.56±4.23mm. At the beginning and ending transect of RHSIVC, about 56.7%and 93.1%of the lumen are enclosed completely by liver parenchyma, which assures the safe performance of DIPS. (3) CD(color Doppler)-guided DIPS operations by percutaneous direct portal venocentesis to RHSIVC are simple, safe and feasible with satisfactory preliminary clinical curative effects.