A 56 year old man suffered a Q wave myocardial infarction complicating a massive lower gastrointestinal haemorrhage, with postinfarction dyspnoea. He had bilateral lower extremity intermittent claudication despite femoropopliteal artery bypass grafting several years previously. Cardiac catheterisation was performed via the left brachial artery because of absent femoral pulses. There was severe global left ventricular systolic dysfunction, ostial left main coronary artery stenosis, right coronary artery occlusion, and there were suitable targets for coronary artery bypass grafting. The aorta was completely occluded below the renal arteries (Leriche phenomenon, panel A). Weak abdominal (ureteral) collateral arteries reconstituted the femoral arteries (arrowhead). A selective angiogram of the left internal mammary artery (LIMA, panel B) showed significantly more collateral supply from the left subclavian artery to the left femoral artery via the inferior epigastric artery.

Internal mammary collaterals to the femoral arteries are well described but little remembered. Surgical harvest of the LIMA for coronary artery bypass interrupts these collaterals and would likely precipitate limb threatening ischaemia.