Partition of coronary flow and cardiac oxygen extraction between coronary sinus and other coronary drainage channels.

• Coronary flow measurements in the intact animal and in man have been based principally on the amount of the coronary sinus drainage. Two assumptions are involved in the use of the coronary sinus drainage as an index of total and of left ventricular coronary flow: (1) The coronary sinus flow is a fixed percentage of total coronary flow, and (2) it represents all or a constant portion of the venous drainage of the left ventricle. Determination of the oxygen consumption of the left ventricle also has been based on the same assumptions, the calculation being the product of coronary sinus flow and the difference in oxygen content between arterial and coronary sinus blood.