Pressure and flow in epicardial coronary veins of the dog heart: responses to positive inotropism.

Peripheral coronary venous pressures and coronary sinus venous flow were measured in the canine heart as well as intramyocardial, intraventricular, aortic, and coronary artery pressures. Maximum coronary venous flow occurred after maximum intramyocardial and peripheral coronary artery pressures had been reached. Maximum venous flow occurred at or following the maximum peripheral coronary vein pressure. Positive inotropic changes induced by stimulation of the right or left stellate ganglia or infusing isoproterenol, norepinephrine, or dobutamine significantly increased intramyocardial pressure, systolic epicardial coronary venous pressure, and systolic coronary venous flow. Mean coronary sinus flow was augmented by all interventions except isoproterenol. The estimated systolic vein resistance was slightly increased following right stellate ganglion stimulation, but not following left stellate ganglion stimulation, isoproterenol, or dobutamine. Norepinephrine reduced this parameter minimally. These data indicate that coronary veins respond differently to a variety of different positive inotropic interventions.