What is Hepatic Veno-Occlusive Disease: Causes, Symptoms, Treatment, Pathophysiology, Epidemiology, Prognosis
Hepatic veno-occlusive disorder or hepatic VOD in a medical condition in which the sinusoidal capillaries present within the liver undergo injury due to consumption of toxic entities like pyrrolizidine alkaloids or oral chemotherapeutic agents which is present in herbal tea. This further leads blockage and impaired functioning of the hepatic veins. This condition though of rare occurrence but has mortality rate greater than thirty percent.
What is Hepatic Veno-Occlusive Disease?
The hepatic veno-occlusive disease is also known as hepatic sinusoidal obstruction syndrome or SOS in which potentially fatal substances enters the body due to consumption of them and causes hepatic injury. Post the toxin exposures, the obstruction of sinusoids take place which further hampers the flow of blood in liver. The liver gets enlarged and inflamed due to damage and the hepatic cells die as a consequence of absence of optimal supply of blood. The obstructed blood supply also causes elevated pressure in the portal vein which causes fluid accumulation within the abdominal region as well as spleen enlargement. Eventually, the liver damage leads to cirrhosis. This condition usually arises after a period of one to three weeks of hematopoietic cell transplantation acclimatized with cytotoxic agents or chemoradiations.
Symptoms of Hepatic Veno-occlusive Disease
The symptoms for hepatic veno-occlusive disease vary slightly depending on the severity of the condition. The hepatic veno-occlusive disease symptoms are:
- Acute Hepatic Veno-Occlusive Disease Symptoms: The symptoms of acute hepatic veno-occlusive disease are:
- Chronic Hepatic Veno-occlusive Disease Symptoms: The chronic condition witnesses below symptoms:
- Hepatic encephalopathy
- Muscle weakness
- Abdominal Swelling
- Pale color of skin and eyes.
Epidemiology of Hepatic Veno-Occlusive Disease
The incidence rate for hepatic veno-occlusive disease is directly related to the cases of hematopoietic stem cell transplantation since around sixty percent cases tend to develop the condition. Apart from the transplants the factors that contribute to the condition are chemotherapy and radiation therapy and ingestion of cytotoxic agents.
Prognosis of Hepatic Veno-Occlusive Disease
The outlook for hepatic veno-occlusive disease depends on the causative factor of the condition. When linked to hematopoietic transplant, over thirty percent cases prove to be fatal with a high mortality rate of the severe cases; whereas in the case of chemotherapy, postoperative hepatic failure is common. When the condition arises due to ingestion of cytotoxic agents, then the condition has a scope of full recovery through interruption of the consumption and prevention of further damage to the liver.
Causes of Hepatic Veno-Occlusive Disease
The common causes behind the presence of the condition are:
- Ingestion of pyrrolizidine alkaloids commonly found in Jamaican bush tea.
- Consumption of drugs that are immune suppressants and have cytotoxic effects on the liver like azathioprine and cyclophosphamide.
- Graft versus host disease due to bone marrow transplantation.
- Chemotherapy particularly through oxaliplatin.
Pathophysiology of Hepatic Veno-Occlusive Disease
The occurrence of toxic injury of the hepatic sinusoids is due to impairment and apoptosis of hepatic endothelial cells which leads to the blockage of sinusoids and progressive fibrosis of the hepatic veins. The fat storing cells or stellate cells within the liver get activated and synthesize collagen and extracellular matrix which also contribute to hepatocellular necrosis. This then impairs the blood flow to the liver causing enlargement and inflammation of the liver. It also leads to death of hepatic cells and spleen enlargement.
Risk Factors of Hepatic Veno-Occlusive Disease
The common risk factors that pose a threat of hepatic veno-occlusive disease are:
- Old age of the transplant recipient.
- Age of transplant recipient younger than six years.
- Prominence in female gender.
- Prior cases of abdominal radiations.
- Past history of liver disease or cirrhosis.
- Repetitive chemotherapy
- Patient with advanced malignancy.
- HLA disparity between the donor and the recipient in case of transplant.
Complications of Hepatic Veno-Occlusive Disease
The complications that generally occur due to hepatic veno-occlusive disease are:
- Liver failure
- Renal Failure
- Elevated pressure in the portal venous system.
Diagnosis of Hepatic Veno-Occlusive Disease
The diagnostic procedure for hepatic veno-occlusive disease is based on checking of the symptoms, blood tests and radiography. The tests followed are:
- Blood Test to Detect Hepatic Veno-Occlusive Disease: The blood tests are conducted to check for abnormal functioning of liver. It also checks ingested toxic agents in the blood along with the blood clotting evaluation.
- Ultrasound for Diagnosing Hepatic Veno-Occlusive Disease: It is usually opted to confirm the diagnosis. It checks for liver enlargement or hepatomegaly, abnormalities in the portal vein, thickening of gall bladder wall and ascites.
- CT Scan to Diagnose Hepatic Veno-Occlusive Disease: The CT scan analysis is done to check for hepatomegaly, impairment of liver due to portal vein congestion and ascites.
- Hepatic Veno-Occlusive Disease Diagnosis with Liver Biopsy: In some cases, the liver biopsy is conducted to assess the blood pressure in hepatic and portal veins through insertion of catheter into the vein of the neck.
Treatment for Hepatic Veno-Occlusive Disease
The treatment for hepatic veno-occlusive disease focuses on treating the symptoms and complications rather than treatment of the blockage because there exists no specific treatment for the blockage. The available treatments for the condition are both surgical as well as non-surgical.
- Non-Surgical Measure for Treating Hepatic Veno-Occlusive Disease: The non-surgical treatments include:
- Preventive Medications for Transplants: Medications like Ursodeoxycholic acid is given to the patient to prevent the chances of developing hepatic veno-occlusive disease post the hematopoietic transplantation.
- Balancing Body Fluid Levels: The level of bodily fluids is monitored through limiting the amount of fluid intake and assessing the amount of fluid lost during excretion. A balanced fluid intake to done to prevent dehydration.
- Surgical Measures for Hepatic Veno-Occlusive Disease: Surgical measures are opted when the non-surgical ones fail to provide the desired result. These include:
- Abdominocentesis: This is a surgical measure which is opted for removal of extra fluid from the abdominal region by inserting a hollow needle into the abdomen and sucking the fluid out.
- TIPS: It stands for Transjugular Intrahepatic Portal Systemic Shunting. It is a surgical procedure in which an alternate blood flow route is devised to check for portal venous congestion around the liver.
- Liver Transplant: This measure is opted when liver in completely impaired and no alternative medication prove effective.
Hepatic veno-occlusive disease is a potentially fatal medical condition which occurs due to sinusoidal lesions and damage in the liver. The condition usually arises as a complication to chemotherapy, stem cell transplantation and ingestion of toxins. If the possible causes are eliminated then the chances of recovery are good. In cases where optimal recovery is not observed, then the complications can range from liver failure to death.