Experimental Study of Coronary Circulation by Coronary Artery Catheterization. (Direct effects of various drugs on Coronary Circulation and electrocardiographic changes) : Part I. Introduction and Control Experiment

Abstract

Experimental studies on the coronary circulation in the past have been done mostly on open-chest animals, isolated hearts, or heart-lung preparations. An investigation of hemodynamic changes electrocardiographically under such unphysiological conditions is open to criticism.In order to study the direct effects of drugs on the coronary vessels and the electrocardiographic changes under physiological conditions, the author introduced a catheter via the carotid artery into the left caronary artery in the closed-chest dog under the fluoroscopic control. Various drugs were infused directly into the coronary artery during continuous coronary artery perfusion with the dog's own femoral arterial blood through the catheter.In Part I, as a control experiment, the effects of different concentrations of glucose solution, and different rate of infusion on the coronary vessels were examined ; this was because glucose solution was used to dilute various drugs in this series of experiments.Method As shown in Fig. 1 a catheter was introduced into the left coronary artery in the closed-chest dog under the fluoroscopic control. Through the catheter the left coronary artery was perfused with the dog's own arterial blood conveyed from the femoral artery via a drip counter. Coronary blood flow was measured by the drip counter and blood pressure by the Hamilton manometer. Leads CψD and Cψs were mostly used in taking electrocardiograms.Results(1) Influence of different rates of infusion(a) When 2 cc of glucose solution was infused over 45 seconds at the same time with the whole blood, coronary blood flow increased, and the electrocardiogram showed depression of the S-T segment as weel as of the T wave.(b) When 2 cc of glucose solution was infused over 90, 120, or 180 seconds at the same time with the whole blood, there was little significant change in either coronary blood flow or the electrocardiogram.(2) Influence of concentration (a) When 5 % glucose solution was used, neither coronary blood flow nor the electrocardiogram revealed any significant change.(b) When 10 % glucose solution was used, the coronary blood flow and the electrocardiogram showed a little changes.Conclusions (1) Details of the author's experiments on the coronary circulation through the coronary artery catheterization in the closed-chest dog were presented and discussed.(2) As a control expetiment, the influences of the rate of glucose infusion and concentration of glucose solution were studied. It was found that the coronary blood flow and the electrocardiogram showed no significant changes when a fixed amount of glucose solution was infused at the same time with the whole blood, over a period of 90 seconds or more.The difference in concentration of glucose solusion between 5% and 10% had scarecely any effect.