The interplay of coronary vascular resistance and myocardial compression in regulating coronary flow.

By integrating phasic coronary sinus flow curves in such a way that volume flow during systole plus isometric contraction and that during the remainder of diastole can be compared, the relative contribution of ventricular compression and coronary resistance to mean coronary flow can be assessed. It was found that anoxia, adenylic acid, compression of the aorta or pulmonary artery reduces coronary vascular resistance while epinephrine increases it. The augmentation in coronary mean flow following epinephrine is due solely to the greater force of ventricular contractions. On the basis of such evidence a revival of the "massaging theory" in modified form is suggested. Evidence was incidentally obtained which supports a former conclusion that the coronary sinus drains territories supplied by the right as well as the left coronary artery.