Influence of the myocardium contractile state in the coronary venous flow deviation phenomenon

Twenty-Four mongrel dogs were anesthetized and submitted to normothermic extracorporeal circulation and to selective perfusion of the coronary arteries with flows of 10.0, 5.0 and 2.5 ml/kg body weight/min. A catheter was introduced inside the coronary sinus, in a 2.0 to 2.5 cm extension, for the flow measurements. The following conditions where investigated: Group I-with hearts beating spontaneously; Group II-under ventricular fibrilation; Group III-under stimulation by isoproterenol (200 mcg); Group IV-under artificial estimulation by pace-maker. Results in Group I hearts demonstrated all inverse relationship between the coronary arterial flow and its proportional drainage in coronary sinus. This phenomenon was not altered (p < 0.05) in Group II (fibrilating) and IV (pacemaker, 80-180 bpm). In Group II hearts, under isoproterenol stimulation an inversion of the above pattern occured with linear increasing of the coronary sinus proportional drainage with the coronary arterial flow augmentation. It is concluded that the coronary venous flow distribution pattern is altered by the improvement in myocardial contractility induced by isoproterenol.