An ostial stenosis of the left internal mammary artery graft anastomosed to the left anterior descending artery was responsible for unstable angina in a patient with a previous coronary artery bypass graft. A T-shape arterectomy was performed between the left subclavian artery and left internal mammary artery. Successful revascularization of the lesion was achieved with a carotid-to-subclavian bypass and surgical ostial plasty extending to the proximal left internal mammary graft using a Hemashild a graft. This procedure was performed through a transverse supraclavicular incision to avoid potential hazards of a redo median sternotomy.