Surgical Shunt Procedures and Endoscopic Therapy
Normally, blood from the intestines and spleen is brought to the liver through the portal vein. In people with severe liver damage (cirrhosis) however, the normal flow of blood through the liver is blocked. This can lead to swelling of the liver and potentially the spleen. Blood from the intestines is then rerouted around the liver through small vessels primarily in the stomach and esophagus. Some of these blood vessels become quite large and swollen (varices). These varices may rupture due to high blood pressure (portal hypertension) and thin vessel walls, causing bleeding in the upper stomach or esophagus.
In cases where severe bleeding occurs, surgical shunt procedures may be used to improve the flow of blood through the varices and to stop bleeding and relieve pressure in these swollen blood vessels.
Introduced in 1945, the portal shunt (portal systemic shunt) was the first definitive form of therapy used for patients who had bled from varices. The procedure involves the surgical joining of two veins, the portal vein and the inferior vena cava, to relieve pressure in the portal vein that carries blood into the liver.
Elective portal shunt surgery is performed in only a relatively small number of patients who bleed from esophageal varices. About one-fourth have severe, uncontrollable bleeding requiring emergency surgery.
The shunt operation virtually eliminated recurrent bleeding from varices but its use declined in the 1970's for two major reasons. One was the frequency of encephalopathy (dysfunction of the brain) as a complication. The other was the failure of controlled clinical trials to establish a statistically significant advantage in survival for patients treated with shunts, over those treated with nonsurgical therapy. The failure of portal shunts to enhance survival, reflected the associated complications of encephalopathy and post shunt failure.
This operation was devised to preserve the flow of blood through the portal vein to the liver, while decompressing varices in the stomach and esophagus by joining the splenic vein to the left kidney vein. Studies comparing portal systematic shunts with DSRS, found similar rates of overall mortality and cumulative survival. DSRS had a higher operative mortality but a lower rate of encephalopathy afterwards. Also, patients with alcoholic cirrhosis do poorly with DSRS compared to nonalcoholic cirrhotic patients.
Endoscopic therapy is a way of reducing variceal bleeding without surgery. In one procedure called endoscopic sclerotherapy, a flexible endoscope is used to inject diluted mixtures of sclerosing (hardening) solutions into the esophageal varices. Another technique called variceal banding, involves placing rubber bands around the veins through the endoscope.
The major merit of endoscopic therapy is that it is relatively easy to apply and can be administered at many primary care hospitals. It is commonly used in the initial management of patients with cirrhosis and variceal bleeding. However, patients experiencing gastric (stomach) variceal bleeding, hypertensive gastritis bleeding or repeated esophageal variceal bleeding following endoscopic therapy, should be treated surgically. In this combination, initial endoscopic therapy and selective shunt surgery may significantly improve survival in patients with variceal bleeding.
An important recent advance has been the development of the transjugular intrahepatic portal-systemic shunt (TIPS). TIPS is performed by radiologists using only a local anesthetic and a sedative. A long needle is inserted via the jugular vein in the neck, advanced into a hepatic vein and then into a large branch of the portal vein in the liver. Using an inflatable balloon-tipped catheter tube, the section between the portal vein branch and the hepatic vein is widened and then kept open (stented) with a cylindrical wire-mesh stent.
The major advantages of TIPS are that it dispenses with the need for a general anesthetic and a major surgical procedure, both of which are often poorly tolerated by patients with cirrhosis. Another advantage of TIPS is that it reduces ascites (accumulation of fluid in the abdomen) while the DSRS does not. It has been used successfully to treat severe ascites that no longer respond to the use of drugs (diuretic) to reduce the amount of fluid. TIPS is a valuable innovation but it is not without its hazards. Although the direct mortality from TIPS complications is relatively low (less than 5%), this is true only in the hands of experienced radiologists in specialized centres. Approximately one quarter of patients develop encephalopathy after TIPS and these shunts frequently narrow or block up, requiring additional interventional procedures. In the setting of life-threatening bleeding that cannot be controlled by endoscopic therapy, TIPS is probably the ideal shunt procedure if it is readily available. In patients with portal hypertension who have failed treatment with endoscopic therapy and are candidates for liver transplantation in the near future, TIPS is not the preferred type of shunt. The presence of a surgical shunt makes transplant surgery more difficult and may therefore result in an increased risk of complications following liver transplantation. In patients who have recurrent bleeding in spite of endoscopic therapy and whose liver function is good, DSRS may be preferable in the elective or non-emergency setting. Appropriate clinical comparisons between TIPS, DSRS and endoscopic therapy are not yet available and will help to further clarify the place of TIPS in the management of variceal bleeding.
