The coronary circulation is unique in that it is responsible for maintaining adequate oxygen and substrate delivery to the organ that generates the pressure needed to drive blood throughout the entire circulatory system. In the simplest terms, coronary blood flow is directly proportional to the arterial pressure gradient across the coronary vasculature and inversely proportional to coronary vascular resistance. However, myocardial perfusion is collectively regulated by a complex variety of mechanisms which include: (1) extravascular compressive forces; (2) diastolic time fraction; (3)...