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.

Abstract

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.