Comparative hemodynamic effects of coronary vasodilators and contrast material on the normal and ischemic canine myocardium: determination of the optimal agent for clinical augmentation of coronary blood flow.

The systemic hemodynamic and myocardial effects of potent vasodilators administered directly into the left coronary artery were determined and compared with the actions of contrast material in 10 anesthetized dogs in the normal state and in the presence of segmental myocardial ischemia. Contrast material (Renografin 76) caused systemic hypotension, rise in left ventricular diastolic pressure and decreases in LV dp/dt and dp/dt/LVP in both states. Doses of ATP (7.2 microgram/kg and 20 microgram/kg/min) which are maximally effective in augmenting coronary blood flow caused only mild arterial hypotension and minimal inotropic effects in both states. Nitroglycerin (3 microgram/kg and 10 microgram/kg/min) induced no inotropic effects but slightly greater arterial hypotension than ATP in both states. On the other hand, papaverine HCl (300 microgram/kg and 800 microgram/kg/min) induced profound increases in LV dp/dt and dp/dt/LVP, decreases in LVEDP and arterial hypotension in the non-ischemic state. In the presence of segmental ischemia, papaverine HCl caused significantly less increases in LV dp/dt and dp/dt/LVP, paradoxical increases in LVEDP in 5 dogs and ventricular fibrillation in 3 dogs. Thus, maximally effective vasodilatory doses of ATP causes only small alterations in hemodynamics and myocardial contractile state of the normal and ischemic heart. Similar doses of papaverine induce profound positive inotropic effects which are apparently deleterious to the ischemic heart.