A fistula is referred to as an abnormal connection between two structures. They usually form due to an injury or surgery. Sometimes, an inflammation or infection can also result in the formation of a fistula. ‘Hepato’ refers to the liver, and the formation of a fistula between the hepatic artery and the vein is called a hepato-venous fistula. It is a rare site for a fistula to occur and is difficult to diagnose. Hepato-venous fistula is associated with certain unfavorable outcomes when left untreated. Hence, early diagnosis and treatment are needed for these patients.
What Is Hepato-Venous Fistula?
Hepato-venous fistula is usually detected as an incidental finding during investigations for any other disease. They can be congenital or acquired. The congenital form is present since birth, whereas the acquired condition has been developed after birth due to any reason. It has been found that the acquired type is common among those who have developed this condition. The cause for the acquired type to develop is either blunt or penetrating trauma. The doctor has to find the cause of the disease to arrive at an accurate diagnosis and formulate a proper treatment plan.
What Are the Causes of Hepato-Venous Fistula Formation?
The following are the causes for the formation of hepato-venous fistula:
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Injury or Trauma: A penetrating type of trauma in the abdominal region is the most common cause of hepato-venous fistula.
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Congenital Causes: It usually occurs in syndromic individuals such as those with Osler-Weber-Rendu (a hereditary disease associated with malformation of blood vessels) or Ehler-Danlos syndrome (an inherited disease that affects the connective tissues such as skin, joints, and blood vessels).
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Tumor: The development of a tumor can also lead to an abnormal connection between a hepatic artery and a portal vein.
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Aneurysm: An abnormal ballooning or bulging of the blood vessel can also lead to a fistula formation.
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Iatrogenic: This refers to the fistula formation induced by the surgeon or physician during a medical examination or treatment. The most common iatrogenic causes of hepato-venous fistula are while performing a liver biopsy and percutaneous transhepatic cholangio drainage (or biliary drainage). Liver biopsy is the procedure wherein liver tissues or cells are collected and examined under a microscope for detailed visualization. Percutaneous transhepatic cholangio drainage is a procedure used in the blocked bile duct to drain the bile secretion and release the pressure within the bile duct.
What Are the Signs and Symptoms of a Hepato-Venous Fistula?
The signs and symptoms of a Hepato-venous fistula are as follows:
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Abdominal pain.
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Vomiting.
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Diarrhea.
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Fever.
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Hematemesis (blood in vomit).
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Jaundice (a condition characterized by abnormal bilirubin levels causing yellowish discoloration of the skin, eyes, and mucous membranes).
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The liver or spleen gets enlarged in size.
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Purplish, bulging veins can be seen through the skin in severe cases.
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Gastrointestinal bleeding.
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Congestive heart failure (a condition where the heart muscle cannot pump enough blood).
All of these symptoms do not appear simultaneously. Each symptom occurs at a different time throughout the course of the disease. About 25 % of the patients experience no symptoms at all, and they come to know that they are suffering from this condition after taking a radiograph in the abdomen for a different disease.
What Are the Risk Factors for a Hepato-Venous Fistula?
Certain conditions increase the risk for the development of a hepato-venous fistula. They include:
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Individuals more than 60 years of age.
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Females.
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Patients with underlying medical illnesses such as hypertension (high blood pressure levels).
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Medications like Aspirin (blood thinners) and antifibrinolytics (drugs that control bleeding).
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Obesity.
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Patients with syndromes like Osler-Weber-Rendu and Ehler-Danlos syndrome.
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Patients undergoing investigation or treatment near the liver leading to an iatrogenic cause for the formation of a Hepato-venous fistula.
What Are the Investigations Performed to Diagnose a Hepato-Venous Fistula?
Diagnosis is the most important step before starting the treatment for patients with a hepato-venous fistula.
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Medical History: A thorough medical history regarding the signs and symptoms, past medical conditions, underlying medical illnesses, and allergies must be noted. The doctor must get details about the history, diarrhea, and previous medications.
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Physical Examination: A physical examination of the abdomen is conducted to detect any tenderness, swelling, or enlargement of the liver, spleen, or other organs in the abdominal region is noted down. Signs of portal hypertension, such as ascites (fluid collection within the abdomen), heart failure, and bleeding, if present, are checked and noted. Any rumbling sound or sensation in the abdominal region is checked with the stethoscope. An epigastric bruit is one of the features pointing to the Hepato-venous fistula, wherein a rumbling sound is heard on a stethoscope.
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Laboratory Tests: A liver function test is performed to determine if the levels are in the normal range. Blood tests are done to detect the presence of hepatitis.
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Ultrasound Doppler: A non-invasive investigation method that uses sound waves to detect the blood flow through the blood vessels. It also shows the speed and the direction in which the blood flows and helps find clots, narrowing, and any other pathology related to the blood vessels.
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CT (Computed Tomography) Scan: An imaging technique that uses an x-ray to show detailed images of the abdominal region. The images are displayed on a computer and can also be printed.
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Hepatic Arteriography: An invasive procedure wherein a catheter (a thin, long, flexible tube) is inserted into arteries of the liver through the femoral artery in the thigh. This procedure helps in clearly visualizing the arterial branches within the liver and knowing the cause, size, and location of the fistula.
The above-mentioned diagnostic procedures help arrive at the conclusion of a Hepato-venous fistula and assist in providing a proper treatment strategy to the patient.
What Are the Treatment Modalities for a Hepato-Venous Fistula?
The decision about the appropriate treatment plan depends on the size and location of the fistula and the patient’s condition. Spontaneous closure can occur if the fistula is small in size and asymptomatic, and no treatment is required in such cases. But in patients with large fistulas causing discomfort, immediate intervention is necessary. The following are the various treatment plans for a patient with a hepato-venous fistula:
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Transcatheter Arterial Embolization: A technique that closes the fistula by embolization. Embolization is a minimally invasive procedure that uses gel foam, steel coils, or detachable balloons to occlude the fistula and stop the bleeding. This technique causes a complete closure in 92 % to 100 % of cases and has a recurrence rate of less than twenty percent.
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Surgery: Surgical intervention is the last resort for these patients when all other treatment modalities fail to provide relief. Surgical ligation can be done wherein the hepatic artery is sutured tightly, or the whole or a portion of the liver is removed. The liver can be replaced with a transplant from another person after proper matching to prevent conditions that may precipitate rejection reactions.
Conclusion
Hepato-venous fistula is a rare entity that is often misdiagnosed or found only as an incidental finding during routine radiographs of the abdominal region. Any symptoms felt in the abdomen must be checked with the doctor to diagnose the condition and get treated at an early stage. Angiography is most helpful in the precise diagnosis of the condition and helps to formulate a treatment plan according to the size and location of the fistula. The outcome of the embolization technique is good, with less recurrence but a few cases require the removal of the whole liver, which a transplant can replace.
