What is portal hypertension?
In people with liver failure and cirrhosis, the liver is incapable of processing blood from the bowels. As a result, abnormally high pressure develops within the veins that drain blood from the bowels as the body tries to form other channels for the blood to empty into the main (systemic) circulation. These alternate pathways of blood drainage are known as portosystemic collaterals and consist of fragile veins that surround the esophagus, stomach or other areas in the digestive tract.
Because of the fragility of these veins, they are prone to rupturing, which can result in massive amounts of bleeding. The abnormally high pressure within the veins draining into the liver (portal hypertension) can also result in the formation of fluid seeping from the surface of the liver and collecting in large quantities in the abdominal cavity. This is known as ascites. Therapies that lower the blood pressure within the veins draining into the liver can lessen the formation of ascites and lower the risk of bleeding from the fragile veins (varices).
What treatments can lower the blood pressure in the portal venous system?
A number of therapies can lower the pressure of the veins that drain from the bowel into the liver. The first choice of therapy usually consists of drug therapy with medications known as non-selective beta-blockers. These medications need to be taken everyday to produce an effect. Some people may not be able to remain on beta-blocker therapy if they develop side effects from taking them. Other people on beta-blocker therapy will remain at risk for bleeding from varices and from the development of fluid formation (ascites).
Another approach is to seal off the veins to prevent rupturing. In sclerotherapy, a camera (endoscope) is passed down through the esophagus to inject the abnormal veins with substances that close them off. With variceal band ligation, the abnormal veins are tied off with small rubber bands. Although sclerotherapy and variceal band ligation are very effective in targeting the abnormal and fragile veins around the esophagus, they do not lower the pressure of the blood inside the portal venous system. This portal hypertension may continue to allow fluid to develop inside the abdominal cavity, or may allow bleeding to occur from other areas of the bowel such as the stomach (portal gastropathy).
Transjugular Intrahepatic Portosystemic Shunts (TIPS) and Surgical Shunts
Pressure inside the portal venous system draining blood into the liver can be relieved by shunting blood away from these veins. Surgical portocaval shunts require an abdominal incision followed by sewing together a portion of the portal venous system to the main venous system. Often these two structures are connected using a short piece of tubing made of Teflon®. The surgical shunts are highly effective at reducing the risk of bleeding from varices. Most surgical shunts will also relieve ascites. The main drawback of surgical shunts is that they are major vascular surgery, and may be associated with a high risk of complications in some patients.
Unlike surgical shunts, TIPS is performed through a small nick in the skin, working through specialized instruments, which are passed through the body using an x-ray camera for guidance. The TIPS procedure creates a shunt within the liver itself, by linking the portal vein with a vein draining away from the liver (a hepatic vein) together with a device called a stent-graft. The stent-graft acts as a scaffold to support the connection between these two veins inside the liver. With the TIPS stent-graft in place, the pressure inside the portal veins is relieved by the blood draining through the stent-graft into the vein draining blood away from the liver.
The best way to relieve the excessive pressure within a person's portal venous system is by replacing their liver with a new one capable of filtering the blood. However, many people are not candidates for a liver transplant. The selection process for determining who is a good candidate for a liver transplant may be complicated and require a long period of time. Even in people who are candidates for a liver transplant, less than a third will ever receive a liver; in these people, TIPS may serve as a potentially lifesaving bridge to transplantation while they await the availability of a donor liver.
How well does a TIPS work?
Over 90% of people that undergo TIPS to prevent bleeding from varices will have a relief in their symptoms and experience little to no bleeding thereafter. When TIPS is performed for ascites, 60-80% of people will have relief in their ascites. Some of these patients will no longer require paracentesis, a procedure where a needle is placed into the abdominal cavity to drain away excessive fluid. Other patients will still need paracentesis, but much less often than before the TIPS procedure. When TIPS is performed for other liver conditions, such as Budd-Chiari syndrome, many patients will have a return to nearly normal liver function once the congested blood drains through the TIPS.
How long will a TIPS work?
Unfortunately, the TIPS can develop areas of narrowing or blockage within the liver. Usually, these areas can be detected early through regular ultrasound scans performed every three months. Once an area of narrowing has been identified, it can be treated with a balloon to widen the area of blockage (angioplasty). The angioplasty restores normal blood flow through the TIPS. This procedure, known as a TIPS revision, can be performed as a day procedure on an outpatient basis.
How will I know if I am a candidate for TIPS?
Most patients with portal hypertension do not need to have a TIPS. Patients that have esophageal varices and problems with bleeding can often be managed with the drug therapy described above. However, for those patients that continue to be at risk for bleeding or who cannot tolerate the usual first-line treatments, TIPS may be an effective form of therapy. In patients with ascites who continue to form large amounts of fluids within their abdomen, even while taking water pills (diuretics), and who require frequent sessions of paracentesis to drain away the fluid, TIPS may also be a very effective therapy.
TIPS is performed by an Interventional Radiologist. The Interventional Radiologist will determine from your medical history, physical, blood work and liver imaging (CT scans, ultrasounds and/or MRI scans), in consultation with your gastroenterologist, hepatologist, or surgeon, whether or not you are a candidate for TIPS.
You should discuss all your treatment options with your physician. Some questions to ask include:
- Can my portal hypertension be controlled with drug therapy?
- What medications might be appropriate for me?
- If a procedure is required, am I a candidate for a less invasive, Interventional Radiology treatment like a transjugular intrahepatic portosystemic shunt?
- What are the risks and benefits of the treatment plan prescribed for me?
- What are the risks of TIPS?
Because blood that normally flows through the liver gets bypassed through a TIPS, some of the substances absorbed into the body from the intestines can build-up within the blood stream and produce a condition known as hepatic encephalopathy. This is a condition that can affect your brain, causing difficulty in concentration, excessive sleepiness and, in rare cases, a coma.
Most cases of hepatic encephalopathy are manageable by taking a medication known as lactulose. This is a laxative in a syrup form that reduces the amount of certain types of toxins absorbed by the intestines into the blood stream. In rare situations, a person can develop severe hepatic encephalopathy after TIPS. If this occurs, the TIPS may need to be closed off or a smaller stent placed within the original stent to slow down the amount of blood passing through the TIPS. Other risks of TIPS include hepatic failure, bleeding and infection.