Capacitive effects on canine coronary artery diastolic pressure-flow relationships.

The extent of capacitive effects on coronary diastolic pressure-flow relationships was investigated by proposing a theoretical model and by actually measuring the time constants of the coronary and systemic circulation. The dynamic pressure-flow relationship obtained by an aortic declining pressure perfusion and the static pressure-flow relationship obtained by constant pressure reservoir perfusion were compared to support the theoretical model, which revealed that the capacitive effects could be quantified by the alpha value, i.e. the ratio of the time constants of the coronary and systemic circulations. In 10 anesthetized dogs, the two independent methods disclosed that capacitive effects are limited and diastolic outflow pressure in the coronary circulation is the static zero-flow pressure intercept determined by the vascular tonus and intramyocardial pressure.