Decrease In Coronary Blood Flow Research Articles

Effects of selective coronary embolization on coronary blood flow and coronary sinus venous blood oxygen saturation in dogs.

The cardiovascular effects of selective coronary embolization were studied with improved techniques in an attempt to obtain evidence for the existence of intercoronary reflexes and their role in potentiating myocardial ischemia. These studies demonstrated that embolization of the coronary arterial bed by lycopodium spores produced an initial marked decrease in coronary blood flow followed by a maintained (approximately 10 minutes) increase which was accompanied by an increase in coronary sinus venous oxygen saturation. Supporting evidence was obtained from selective coronary angiograms and from changes in coronary vascular resistance. Attempts at eliminating these responses by certain autonomic blocking agents (atropine, hydralazine, tetraethylammonium chloride, hexamethonium, and dibozane), surgical denervation of the heart, and adrenalectomy were all ineffective. Experimental evidence obtained by comparing the initial effect of embolization with pitressin vasoconstriction and coronary occlusion all led to the conclusion that reflex coronary spasm does not occur during coronary occlusion. The cause of the initial decrease in coronary blood flow during embolization (lycopodium spores) is, therefore, mechanical block within the distribution of the vessel by the emboli.

Experimental Study of Coronary Circulation by Coronary Artery Catheterization : (5) Direct Effects of Various Drugs on Coronary Circulation and Electrocardiographic Changes. Direct Effect of Nicotine and Ethyl Alcohol on Coronary Circulation and the Electrocardiographic Changes

Nicotine has been believed to exert a vasoconstrictor action on the coronary vessels ; some investigators, however, recently claim a vaso-dilator action of the drug on the coronary vessels. No agreement has yet been reached on the action of ethyl alcohol as to whether it exerts a vaso-constrictor a vaso-dilator action on the coronary vessels. The author attempted to examine the action of both drugs on coronary circulation following the direct infusion of each drug into the left coronary artery through a coronary artery catheter in anesthetized, closed-chest dogs. Electrocardiographic changes were also studied.Method Using the same methods as in parts II, III and IV, the experiments were performed 12 times on 3 adult dogs. Leads CψD and CψS, representing right and left ventricular electrocardiogram respectively, were used in taking the serial electrocardiograms.Results(1) Nicotine(a) With 0.133 mg of nicotine coronary wedge pressure remained unchanged, and femoral arterial pressure rose slightly in the experiments with coronary artery perfusion from the dog's own femoral artery. With the same dose of the drug coronary blood flow increased in the experiments with coronary artery perfusion from a donor dog's femoral artery.(b) Infusion of 0.25 mg of nicotine caused a slight decrease in coronary blood flow with unchanged coronary wedge and femoral arterial pressures in the experiments with coronary artery perfusion from a donor dog's femoral artery.(c) Infusion of 0.4 mg of nicotine caused a slight decrease in coronary blood flow and unchanged coronary wedge and femoral arterial pressures in the experiments with coronary artery perfusion from a donor dog's femoral artery.(d) With 0.67 mg of nicotine coronary blood flow increased slightly, coronary wedge pressure remained unchanged, and femoral arterial pressure rose slightly in the experiments with coronary artery perfusion from the dog's own femoral artery. With the same dose of the drug coronary blood flow increased slightly and coronary wedge pressure remained unchanged in the experiments with coronary artery perfusion from a donor dog's femoral artery.(e) Infusion of 1.0 mg of nicotine slightly increased coronary blood flow in the experiments with coronary artery perfusion from the dog's own femoral artery. Coronary wedge pressure remained unchanged and femoral arterial pressure rose slightly.(2) Ethyl alcohol(A) Experiments with coronary artery perfusion from the dog's own femoral artery.(a) Infusion of 1.7% ethyl alcohol caused a slight increase followed by a decrease in coronary blood flow. Coronary wedge and femoral arterial pressures remained unchanged.(b) With 3.3% ethyl alcohol coronary blood flow decreased while coronary wedge and femoral arterial pressures showed no change.(c) With 5.0% ethyl alcohol coronary blood flow decreased and coronary wedge and femoral arterial pressures remained unchanged.(B) Experiments with coronary artery perfusion form a donor dog's femoral artery.(a) With 0.67% ethyl alcohol coronary blood flow increased, while coronory wedge pressure fell and femoral arterial pressure remained unchanged.(b) With 1.7% ethyl alcohol coronary blood flow increased slightly, coronary wedge pressure fell, and femoral arterial pressure remained unchanged in some and rose in other.(c) With 3.3% ethyl alcohol coronary blood flow decreased, coronary wedge pressure fell, and femoral arterial pressure remained unchanged.Conclusions(1) Nicotine exerts no direct action on the coronary vessels.(2) A small dose of ethyl alcohol tends to exert a vaso-dilator action, while a large dose causes vaso-constrictor of the coronary vessels.(3) Nicotine causes hardly any change in the electrocardiogram.(4) The more ethyl alcohol is used, the more the electrocardiogram changes. The changes are mostly depression of the S-T segment and inversion of the T wave.

Experimental Study of Coronary Circulation by Coronary Artery Catheterization : (4) Direct Effects of Various Drugs on Coronary Circulation and Electrocardiographic Changes. Direct Effects of Theophylline Ethylenediamine on Coronary Vessel and the Electrocardiographic Changes.

The author attempted to examine the action of theophylline ethylenediamine, so-called coronary dilator, by following the effect of the direct infusion of the drug into the left coronary artery through a coronary artery catheter in anesthetized, closed-chest dogs. Electrocardiographic changes caused by the infusion of the drug were also studied.Method : In addition to the experimental method described in part I, the left coronary artery was also perfused from a donor dog's femoral artery at a constant blood pressure. The experiments were done 6 times on 2 adult dogs. Leads CψD and CψS, representing right and left ventricular electrocardiogram, respectively, were used in taking serial electrocardiograms.Results : (1) Experiments with coronary artery perfusion from the dog's own femoral artery(a) With 12.5 mg of theophyline ethylenediamine coronary blood flow flincreased, while coronary wedge pressure and femoral arterial pressure showed no change.(b) With 25 mg of theophylline ethylenediamine coronary blood flow decreased, coronary wedge pressure showed no change, and femoral arterial pressure fell.(c) With 125mg of theophylline ethylenediamine coronary blood flow decreased, coronary wedge pressure fell and femoral arterial pressure became markedly reduced.(2) Experiments with coronary artery perfusion from a donor dog's femoral artery under constant blood pressure(a) Infusion of 12.5 mg of theophylline ethylenediamine caused a slight decrease in coronary blood flow, an elevation in coronary wedge pressure and no change in femoral arterial pressure.(b) With 25 mg of theophylline ethylenediamine coronary blood flow increased, while coronary wedge pressure and femoral arterial pressure fell.(c) Infusion of 62.5 mg of theophylline ethylenediamine caused an increase in coronary blood flow, a fall in coronary wedge pressure and a marked fall in femoral arterial pressure.Conclusions : (1) Theophylline ethylenediamine tends to exert a vaso-dilating action on the coronary vessels.(2) Infusion of a large amount of theophylline ethylenediamine caused a dangerous decrease incoronary blood flow followed by a fall in aortic pressure.(3) The electrocardiogram showed a tendency to elevation of the S-T segments with a slight increase in the heart rate.

冠循環の神経性調節に関する研究(第3報) : 迷走神経末梢端刺戟による冠流血量の変化

In the present patper, the effects of the stimulation of the peripheral end of the vagal nerve were reported, with consideration of the relationship between vasomotor and hemodynamic factors. Experimental methods were same as already described in the Part I of this study.Results were as follows : 1) Stimulations of the peripheral ends of the cut vagal nerves were performed, on the left side in 15 experiments on 11 dogs, on the right side in 4 experiments on 4 dogs. During the stimulation of the vagal nerve, the depression of the blood pressure and the bradycardia occurred in all experiments.2) Coronary blood flow decreased with the depression of the blood pressure, for example, as shown in Fig. 1. But, in about a half cases of all experiments, coronary blood flow increased initially for a short time, and then decreased with marked depression of the blood pressure, for example, as shown in Fig. 2 and 3. Experimental results of all cases in the initial increase and maximal decrease in coronary blood flow, were shown in Tab. I and II, respectively.3) Coronary vascular resistance decreased markedly during phases of the initial increase in coronary blood flow (white dots in Fig. 4). In addition, it decreased also during phases of the maximal decrease in coronary blood flow, in over a half cases of experiments (black dots in Fig. 4). Changes in coronary vascular resistance in the vagal nerve stimulation (Fig. 4) were quite different from that in the depressor response by the stimulation of the proximal end of the vagal nerve (Fig. 5) (already discussed in Part I of this study). It suggests coronary vasodilatory actions by the stimulation of the peripheral end of the vagal nerve.4) It seems likely that, the more decreases the heart rate, the more decreases the coronary vascular resistance, when the degree of the bradycardia is not over approximatery 40 %, but, in marked bradycardia, the coronary vascular resistance tended to increase, as shown in Fig. 6.The initial increase in coronary blood flow (white dots in Fig. 6), however, occurred with either very slight or marked bradycardia, in spite of depression of the blood pressure. It suggests the vagal active vasodilatation.5) From results reported in this paper, it may be concluded that ; the vagal nerve stimulation produces the coronary vosodilation and the initial increase in coronary blood flow ; but, the coronary blood flow decreases thereafter, or throughout during the stimulation from its beginning, because of the marked depression of the blood pressure ; the bradycardia itself may have some vasodilatatory effects on the coronary blood flow.

The effect of immersion hypothermia on coronary blood flow.

In severe hypothermia resistance in the coronary vascular bed is reduced and flow continues despite very low aortic pressure. Moderate artificial acceleration of the hypothermic heart at constant coronary perfusion pressures produces a decrease in coronary blood flow. This decrease in flow is roughly proportional to the increase in heart rate and is due to the longer periods of extravascular compression in each cardiac cycle. Epinephrine produces transient improvement in blood pressure and coronary blood flow but is followed in a matter of minutes by ventricular fibrillation.