Bilateral ligation of the internal mammary arteries was proposed by Battezzati and coworkers1 to increase the flow of blood from the internal mammary arteries to the coronary arteries via the pericardiophrenic arteries. In dogs and human cadavers, they injected methylene blue or India ink into the internal mammary artery, after its ligation in the second intercostal space and demonstrated the dye in epicardial fat and myocardial vessels and in vessels about the roots of the aorta and pulmonary arteries. They described the normal course of the pericardiophrenic arteries arising from the internal mammary arteries and ramifying over the pericardium. In a report that includes a review of the literature, Glover et al.,2 using Evans blue dye, injected the internal mammary arteries of dogs immediately following their ligation. They found similar anastomoses. Comparative injection studies in dogs with and without ligation of the internal mammary arteries were not performed.