A peritoneovenous shunt (PVS) is a device that is inserted surgically into the body to create a passage between the peritoneum (abdominal cavity) and the jugular vein to treat refractory cases of peritoneal ascites. Ascites is a condition in which an excessive amount of fluid builds up within the abdominal cavity.
Purpose
The abnormal build-up of fluid in the spaces found between the tissues and organs of the abdominal cavity is a common symptom of liver disease such as cirrhosis of the liver, but approximately 10% of the diagnosed cases occur as a side effect of several types of cancers, such as ovarian, gastric, exocrine pancreatic, and colorectal cancers and lymphoma. This condition is known as ascites and it causes pain and discomfort in patients. When doctors can not treat advanced ascites with medication, they recommend an operation such as the PVS procedure as a means to empty the abdomen of the accumulated fluid.
The ascites that results from cancer contains high levels of proteins. It occurs because of functional imbalances in the cells of the organs affected by the cancer and because the walls of the capillaries containing the normal abdominal fluid start leaking. Depending on the type of cancer, there may also be a decrease in the ability of the lymphatic system of the body to absorb fluids.
Precautions
The PVS procedure is restricted to patients with livers that function normally. Additionally, the required veins must be healthy so as to allow the insertion of the shunt device. The PVS insertion is not performed in the following cases:
patients having undergone previous extensive abdominal surgery
In cases of ascites due to cancer (malignant ascites), there is a concern that the use of a PVS could enhance the spread of the cancer. In evaluating a cancer patient as a candidate for a PVS, the risk of cancer spread must be balanced against pain/discomfort relief, quality of life issues, and the expected survival period.
Description
The most common PVS device is the LeVeen shunt, used since the 1970s to relieve ascites due to liver disease and since the 1980s for cancer-related ascites. It consists of a plastic or silicon rubber tube fitted with a pressure-activated one-way polypropylene valve that connects the peritoneal space where the fluid is collecting to a large vein located in the neck called the jugular vein. The tube enters the jugular vein and terminates in another large vein called the superior vena cava that returns blood to the heart. Thus, the fluid goes from the abdominal cavity to the venous blood circulatory system and is then eliminated by the kidneys. The function of the one-way valve is to prevent blood from flowing back into the peritoneal space.
The PVS is inserted under the skin of the chest under local or general anesthesia, depending on the general health condition of the patient.
An alternative option to treat ascites due to cirrhosis is to use a transjugular intrahepatic portosystemic shunt (TIPS). This is also a tube that is passed through the skin of the neck and into the jugular vein but it is pushed all the way through the liver and into the portal vein, which drains into the liver. It thus creates a shunt of blood across the liver in an attempt to reduce pressure and fluid formation.
Preparation
Abdominal computed tomography scans are used to determine the extent of the ascites. Lab tests are usually performed to determine if the excess abdominal fluid is infected and other imaging studies such as ultrasound may be performed to assess the general condition of the veins selected for insertion of the PVS tube. For the operation, the patient is usually injected with a mild sedative and local anesthetic. The surgeon uses a puncture needle to create the opening required for insertion of the PVS device so as to avoid surgical incisions which take longer to heal.
Aftercare
Antibiotics are usually prescribed for approximately four days after surgery. Any fever or chills that the patient experiences should be reported to the doctor without delay.
Risks
Complications following PVS insertion are very common and include infection, leakage of fluid, fluid build-up in the lungs, problems with blood coagulation, heart failure and blockage of the PVS device.
Normal results
The PVS insertion is considered successful when the abdominal fluid build-up gradually disappears after the operation.
Abnormal results
The most common complication resulting from PVS insertion is obstruction of the valve or tube, which can be due to a blood clot or to scar tissue forming around the shunt and eventually blocking it. This complication occurs in approximately 60% of cases during the first year of follow-up.
Resources
BOOKS
Drake, J. M., and C. Sainte-Rose. Shunt Book. New York: Blackwell Science Publishers, 1995.
Grannis, F. W, et al. "Fluid Complications." In Cancer Man agement: A Multidisciplinary Approach. Melville, NY: Publisher Research & Representation, Inc., 2000.
PERIODICALS
Bechstein, W. O., et al. "Peritoneovenous Shunting for the Treatment of Massive Ascites". New England Journal of Medicine 322 (1990): 1750-1756.
LeVeen, H. H. "The LeVeen Shunt." Annual Reviews of Medi cine 36 (1985): 453-469.
Lee, C. W., G. Boclek, and W. Faught. "A Survey of Practice in Management of Malignant Ascites." Journal of Pain and Symptom Management 16 (1998): 96-101.
Runyon, B. A. "Care of Patients with Ascites." New England Journal of Medicine 330 (1994): 337-342.
Monique Laberge, PhD
Abdomen
—The part of the body which lies between the diaphragm and the rim of the pelvis.
Circulatory system
—The circulatory system consists of the heart and blood vessels. It serves as the body's transportation system.
Esophagus
—The part of the digestive tract that brings food from the mouth to the stomach.
Jugular veins
—Large veins returning the blood from the head to the heart into two branches (external and internal) located on each side of the neck.
Lymph
—Colorless liquid that carries the white blood cells in the lymphatic vessels.
Lymphatic system
—A subsystem of the circulatory system, it consists of lymphatic fluid, lymphatic vessels, and lymphatic tissues (lymph nodes, tonsils, spleen, and thymus). It returns excess fluid to the blood and defends the body against disease.
Peritoneum
—Smooth membrane which lines the cavity of the abdomen and which surrounds the viscera (large interior organs) forming a nearly closed bag.
Peritonitis
—Inflammation of the peritoneum.
Vena cava
—Very large veins. There are two vena cava in the body. The superior vena cava returns blood from the upper limbs, head, and neck to the heart and the inferior vena cava returns blood from the lower limbs to the heart.
