Portal decompression is indicated in patients who have portal hypertension complicated by gastrointestinal hemorrhage from esophageal varices that are not effectively controlled with sclerotherapy injections. Some procedures completely interrupt portal venous flow to the liver (end-to-side portacaval shunt), while others selectively decompress the portal system via a collateral shunt (side-to-side portacaval, splenorenal, and mesocaval). The procedure selected will depend upon the patency of the portal and splenic veins, the results of liver function studies, the amount of portal venous blood being shunted, whether the patient is bleeding acutely, and whether the patient is a candidate for liver transplantation.
Selection of patients should be based on their clinical status, results of liver function studies, and interpretation of hepatic hemodynamics as determined by radiologic studies. Patients considered for shunting procedures generally should be under 60 years of age. Ideally, there should be no evidence of encephalopathy, jaundice, ascites, or muscle wasting. Serum albumin should be above 3 g/dL, prothrombin time greater than 1.5 times normal, or other evidence of intact hepatic synthetic function. Deviation from these criteria does not absolutely contraindicate surgery, but the surgical risk is directly proportional to the degree of hepatic decompensation.
Shunting procedures for portal hypertension can be divided into three types: portacaval, splenorenal, and mesocaval. Figures a to f show diagrammatically the basic surgical choices for diversion of the portal venous flow.
The primary indication for portacaval shunt is the control of massive upper-gastrointestinal hemorrhage from varices which cannot be controlled with endoscopic ablation or by transjugular intrahepatic portosystemic shunts (TIPS). Portacaval shunts are sometimes preferred when there has been prior splenectomy, splenic vein thrombosis, reversal of flow in the portal vein, thrombosed splenorenal shunt, ascites, or hepatic vein thrombosis. The selection of a direct portacaval shunt, of course, depends upon the demonstration of a patent portal vein preoperatively or at laparotomy.
The side-to-side anastomosis (figure a) has been preferred by some in the presence of portal hypertension with no evidence of a rise in pressure on the hepatic end of the temporarily occluded portal vein. This suggests that the arterial blood supply is going through the liver and that lowering of the portal pressure by the side-to-side anastomosis with the vena cava will not result in diversion of the arterial supply to the liver. Another advantage of this type of shunt is that it decompresses the hepatic sinusoids, and this may be beneficial in the treatment of patients with intractable ascites accompanied by variceal hemorrhage.
The usefulness of the portacaval shunt in the treatment of refractory ascites is not accepted universally, although several studies have suggested that this is an effective mode of therapy. If shunting is indicated to control ascites, a direct side-to-side shunt or a side-to-side H-shunt with an 8- or 10-mm ringed PTFE interposition graft is usually preferred. This is ...