Pulmonary arteriovenous aneurysm is a congenital pulmonary vascular malformation. The blood vessels are enlarged and tortuous or form cavernous hemangiomas. The blood in the pulmonary artery flows directly into the pulmonary veins without passing through the alveoli. The pulmonary artery and veins are directly connected to form a short circuit. It was first discovered and described by Churton in 1897 and was called multiple pulmonary artery aneurysms. In 1939, Smith used cardiovascular angiography to confirm this disease. There are many names in the literature, such as pulmonary arteriovenous aneurysm, haemagiectasis of the lung, and haemonreac telangiectasia with pulmonary artery aneurysm. In addition, this disease is familial and related to genetic factors, such as hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease).