Anomalous origin of left internal mammary artery arising directly from the aortic arch.

To cite: Hailan A, Obaid D, Zaidi A, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2014206583 DESCRIPTION A 72-year-old man who had undergone coronary artery bypass grafting 18 years previously (including left internal mammary artery (LIMA) graft to the left anterior descending artery) presented with an acute coronary syndrome. He underwent angiography to assess coronary artery bypass graft patency. Attempts to locate the origin of the LIMA in the left subclavian artery were unsuccessful (figure 1A). An aortic arch angiogram was performed using a 4 Fr Pigtail catheter (figure 1B). This revealed that the LIMA arose directly from the aortic arch, which was subsequently selectively engaged with a 5 Fr multipurpose catheter (figure 1C). The LIMA arises from the inferior aspect of the proximal third of the subclavian artery in 92% of cases, the middle third in 7% and the distal third in 1% of cases. There are reports of the LIMA originating from the junction of the left subclavian artery and aorta, and from the vertebral artery. To the best of our knowledge, this is the first description of the LIMA arising directly from the aortic arch. Angiographic evaluation of the LIMA is not routinely performed prior to coronary artery bypass grafting. This case therefore exemplifies the importance of performing non-selective aortic arch angiography before concluding that the LIMA graft is occluded.