The term pulmonary arteriovenous malformation (AVM) refers to lesions that have abnormal communications between the pulmonary arteries and pulmonary veins. Numerous other names have been used in the past to describe these lesions, such as pulmonary telangiectasias, aneurysms, fistulas, hemangiomas, and cavernous angiomas. These lesions can be congenital, usually as part of the hereditary hemorrhagic telangiectasia, also known as Rendu–Osler–Weber syndrome, or acquired from bronchiectasis, infections, hepatic cirrhosis, mitral stenosis, malignancies, or trauma. AVMs have been described based on number (single vs. multiple), location (unilateral vs. bilateral; parenchymal vs. pleural), and size or type of drainage (simple vs. complex).1,2