Symptoms vary from being totally asymptomatic to
severe with presentation in childhood with cyanosis and shortness of breath
on exertion, congestive heart failure, or respiratory failure. Murmurs or
bruits over the site of the PAVM may be present in half the patients and
louder during inspiration. Increased FiO2 (fraction of inspired oxygen)
may not significantly improve oxygenation. Secondary polycythemia is present
and the degree depends on the severity of cyanosis. The condition is
associated with hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber
syndrome) in 60 to 70% of patients; conversely, 15 to 30% of patients
with hereditary hemorrhagic telangiectasia have PAVM. Hemoptysis from
rupture of the lesions may occur. Thrombosis may occur within the fistula
with systemic embolization leading to neurological complications (transient
ischemic attacks, hemiplegia, brain abscesses, or seizures) in about
one-third of the patients. Hemothorax and/or hemoptysis are often lethal
complications of arteriovenous fistulae. Because mortality is high in
symptomatic patients, surgical resection of the involved lung segment is
often performed. However, embolotherapy based on occlusion of the feeding
arteries of the PAVM is currently the treatment of choice.