Pulmonary arteriovenous fistula is a condition in which an abnormal connection (fistula) develops between an artery and vein in the lungs. As a result, blood passes through the lungs without receiving enough oxygen.

Pulmonary arteriovenous fistulas are usually the result of a genetic disease that causes the blood vessels of the lung to develop abnormally. Fistulas also can be a complication of liver disease.

Patients with Rendu-Osler-Weber disease (ROWD) -- also called hereditary hemorrhagic telangiectasis (HHT) -- often have abnormal blood vessels in many parts of the body. These abnormal vessels can be in the lungs, brain, nasal passages, liver, and gastrointestinal organs. This condition is slightly more common in women than in men.

Many people have no symptoms. When symptoms occur, they can include:

• Bloody sputum
• Difficulty breathing
• Difficulty exercising
• Nosebleeds (in patients with HHT)
• Shortness of breath with exertion

Other possible symptoms include:

• A murmur heard with a stethoscope placed over the abnormal blood vessel
• Abscesses or infections of the heart valves
• Blue skin (cyanosis)
• Clubbing of the fingers

• High red blood cell count
• Low blood oxygen level

Tests include:

• Chest x-ray
• Chest CT scan
• Pulmonary arteriogram

A small number of patients who have no symptoms may not need specific treatment. For most patients with fistulas, the treatment of choice is to block the fistula during an arteriogram (embolization).

Some patients may need surgery to remove the abnormal vessels and nearby lung tissue.

The outlook for patients with HHT is not as good as for those without HHT. It is possible for the condition to come back after blocking the fistula (embolization).

Surgery to remove the abnormal vessels usually has a good outcome, and the condition is not likely to return.

Major complications after treatment for this condition are unusual. Complications may include:

• Bleeding in the lung
• Blood clot that travels from the lungs to the arms, legs, or brain (paradoxical embolism)
• Infection in the brain or heart valve

Call your health care provider if you often have nosebleeds or difficulty breathing, especially if you also have a history of HHT.

Because this condition is often genetic, prevention is not usually possible.

Bernstein D. Other Congenital Heart and Vascular Malformations. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 432.