Unique collateralisation between the left internal thoracic artery and the coeliac artery.

Collateralisation around stenotic or occlusive arterial disease is a commonly observed adaptation for maintenance of arterial perfusion. It occurs through pathways of well-understood embryological origin. Examples include Winslow's pathway (internal thoracic artery to iliac artery via the epigastric arteries) and the arc of Riolan (between superior and inferior mesenteric arteries). In this article, we describe a pathway of collateralisation around stenotic disease of the coeliac and superior mesenteric arteries in a 76-year-old man with an abdominal aortic aneurysm. The collateral pathway was identified on computed tomography angiography between the left internal thoracic artery in the thorax and the coeliac artery in the abdomen via the left inferior phrenic artery. This has implications for routine cardiac surgery, such that left internal thoracic artery harvest during coronary artery bypass surgery would likely result in acute ischaemia of the abdominal viscera.