Congenital arteriovenous fistula between descending aorta and the left innominate vein

Thoracic aortocaval fistulae are rare entities where a direct shunt between thoracic arteries and systemic veins is seen. They can be traumatic or congenital in origin. Congenital thoracic aortocaval fistulae usually involve descending aorta and azygos, hemiazygos systems. Presenting symptoms range from continuous murmur to signs of congestive heart failure. In this case report, imaging findings of a 3-year-old girl referred for continuous murmur over the left sternal border are presented. Computed tomography angiography revealed multiple tortuous vessels along the descending aorta with a course toward the left brachiocephalic vein, and was suspicious for an aorta-venous fistula. Subsequent digital subtraction angiography for treatment planning showed a fistula originating at the level of the left 6th intercostal artery, with direct drainage into the left brachiocephalic vein without involvement of the azygos/hemiazygos system.