Pulmonary arteriovenous fistulas are usually the result of abnormal development of the blood vessels of the lung. Most occur in people with hereditary hemorrhagic telangiectasia (HHT). These people often have abnormal blood vessels in many other parts of the body.

Fistulas also can be a complication of liver disease or lung injury, although these causes are much less common.

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

• Bloody sputum
• Difficulty breathing
• Difficulty exercising
• Nosebleeds
• Shortness of breath with exertion
• Chest pain 
• Blue skin (cyanosis)
• Clubbing of the fingers

The health care provider will examine you. The exam may show:

• Abnormal blood vessels (telangiectasias) on the skin or mucous membranes
• Abnormal sound, called a murmur when a stethoscope is placed over the abnormal blood vessel
• Low oxygen when measured with a pulse oximeter

Tests that may be done include:

• Arterial blood gas, with and without oxygen (usually oxygen treatment does not improve the arterial blood gas as much as expected)
• Complete blood count (CBC)
• Chest x-ray
• Chest CT scan
• Echocardiogram with bubble study to check the function of the heart and assess for presence of a shunt
• Lung function tests
• Perfusion radionuclide lung scan to measure breathing and circulation (perfusion) in all areas of the lungs
• Pulmonary arteriogram to view the lung arteries

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

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

When arteriovenous fistulas are caused by liver disease, the treatment is a liver transplant.

The outlook for people with HHT is not as good as for those without HHT. For people without HHT, surgery to remove the abnormal vessels usually has a good outcome, and the condition is not likely to return.

For people with liver disease as a cause, prognosis depends on liver disease.

Complications may include:

• Bleeding in the lung
• Stroke due to blood clot that travels from the lungs to the arms, legs, or brain (paradoxical venous embolism)
• Infection in the brain or heart valve, especially in patients with HHT

Contact your provider if you often have nosebleeds or difficulty breathing, especially if you also have a personal or family history of HHT.

Because HHT is often genetic, prevention is not usually possible. Genetic counseling may help in some cases.

Arteriovenous malformation - pulmonary

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Stowell J, Gilman MD, Walker CM. Congenital thoracic malformations. In: Shepard JO, ed. Thoracic Imaging: The Requisites. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 8.

Valente AM, Dorfman AL, Babu-Narayan SV, Krieger EV. Congenital heart disease in the adolescent and adult. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 82.

Updated by: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.