Pulmonary arteriovenous malformation

Pulmonary arteriovenous malformation (PAVM), also known as pulmonary arteriovenous fistula or pulmonary arteriovenous aneurysm, is a rare vascular anomaly in which abnormal direct connections form between pulmonary arteries and pulmonary veins, bypassing the normal capillary bed of the lungs. This right-to-left shunt allows deoxygenated blood to pass through the lungs without being oxygenated, leading to hypoxemia (low blood oxygen levels). PAVMs can occur as isolated sporadic lesions, but approximately 70-80% of cases are associated with hereditary hemorrhagic telangiectasia (HHT, also known as Osler-Weber-Rendu syndrome), an autosomal dominant disorder caused by mutations in genes such as ENG or ACVRL1. The condition primarily affects the pulmonary vascular system but can have serious consequences for the brain and other organs due to paradoxical embolism, where clots or bacteria bypass the lung's filtering function and travel to the systemic circulation. Key symptoms include dyspnea (shortness of breath), cyanosis (bluish discoloration of the skin), hemoptysis (coughing up blood), and exercise intolerance. Many patients may be asymptomatic, with the malformation discovered incidentally on chest imaging. Serious complications include stroke, brain abscess, and massive hemoptysis, which can be life-threatening. Physical examination may reveal digital clubbing and a bruit over the affected area of the lung. Oxygen saturation is often reduced, particularly in the upright position (orthodexia), and patients may experience platypnea (worsening breathlessness when upright). Diagnosis is typically established through contrast echocardiography (bubble study), chest CT angiography, or pulmonary angiography. The primary treatment is transcatheter embolotherapy, a minimally invasive procedure in which the feeding arteries of the PAVM are occluded using coils or vascular plugs. This approach has largely replaced surgical resection as the standard of care. Patients with HHT-associated PAVMs require lifelong surveillance, as new lesions may develop or treated lesions may recanalize. Antibiotic prophylaxis before dental and surgical procedures is recommended to reduce the risk of brain abscess. Screening for PAVMs is advised in all patients diagnosed with HHT.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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