An abnormal passageway between an artery and vein that occurs in the blood vessels of the lungs. This produces a right-to-left shunting of blood (blood is not oxygenated properly) and is present in as many as one third of cases of hereditary hemorrhagic telangiectasia (rendu-osler-weber disease). There may not be any symptoms, or symptoms may include difficulty breathing or bloody sputum . Other symptoms that may occur include blue skin ( cyanosis ), clubbing of the fingers (enlargement of the tips of the fingers), and a murmur heard with a stethoscope placed over the malformation. Treatment may be unnecessary if there are no symptoms; symptomatic malformations may require surgical resection (cutting out) or embolization (clotting off).

Alternative Names

Pulmonary arteriovenous malformation; Arteriovenous malformation - pulmonary

Causes, incidence, and risk factors

Pulmonary arteriovenous fistulas are congenital (present at birth) malformations that result from abnormal development of the blood vessels of the lung. Patients with Rendu-Osler-Weber disease (ROWD), also called hereditary hemorrhagic telangiectasis (HHT), frequently have abnormal blood vessel development at many sites in the body, including the lungs, brain, nasal passages, liver, and gastrointestinal organs. This condition is slightly more common in women than in men.

Signs and tests

The oxygen saturation level in the blood is decreased. There may be an abnormally high red blood cell count. The chest radiograph usually demonstrates the presence of the abnormal blood vessels. The chest CT scan confirms the presence of the abnormal blood vessels. A pulmonary arteriogram (motion picture x-rays taken after the injection of dye) is used to make a "road map" of the abnormal blood vessels before surgery or other treatments.

Treatment

A small number of patients who have no symptoms may need no specific treatment. For most patients with either single or multiple fistulas, operation for removal of the abnormal vessels and the adjacent lung tissue is the treatment of choice. For some patients, with favorable anatomy of the abnormal blood vessels, embolization (blockage) of the fistula at the time of arteriogram may be possible.

Expectations (prognosis)

The prognosis for patients with HHT is less favorable than for those without HHT. The results of surgery are very good, and recurrence is unlikely. Recurrence is possible after embolization.

Complications

The most worrisome complication for patients with untreated pulmonary arteriovenous fistulas is "paradoxical embolism"—embolization of blood clot from the lungs to the arms, legs, or brain (producing stroke).Major complications after treatment for this condition are unusual.

Calling your health care provider

Patients with frequent nosebleeds or difficulty breathing, especially if there is also a history of HHT, should consult their physician.

Prevention

Because this condition is congenital, prevention is not usually possible.