Paravertebral Arteriovenous Malformation with Venous Connection to Left Iliac Vein

Abstract

An unusual systemic arteriovenous malformation arising from the left 9th intercostal artery, taking a caudal course through the left paravertebral veins, eventually drained into the left ascending lumbar vein, as illustrated at computed tomography and angiography. An embryologic maldevelopment of the azygos venous system is not the only possible explanation for venous drainage in the caudal direction. We believe that predominant venous drainage can take place in either direction because of the potentially bidirectional flow in the vertebral venous systems.