Enhancement of non-coronary collateral blood flow from the internal thoracic arteries: the theoretical and practical basis of an alternative method of myocardial blood supply.

Non-coronary collateral blood flow arrives to the heart from mediastinal, bronchial, and pericardial channels. These enter the heart through the pericardial reflections surrounding the pulmonary and systemic veins, as well as from the vasa vasorum of the aorta and the pulmonary artery leading to and from the myocardium. Before the advent of cardiopulmonary bypass surgery, surgical bilateral ligature of the internal thoracic arteries (ITAs) was performed in patients with ischemic heart disease to increase the perfusion pressure within the channels leading to the heart.