Sudden Occlusion of Coronary Arteries Following Removal of Cardiosensory Pathways

In a previous paper1experiments were reported showing that in dogs morphine and ether anesthesia markedly reduced the mortality rate after ligation of coronary arteries. In those experiments sudden death following ligation of the circumflex branch of the left coronary artery in the anesthetized dogs occurred in 25 per cent. Similar ligation in dogs in the conscious state resulted in a mortality rate of 75 per cent. Again, when ligation of the anterior descending branch of the left coronary artery was effected with anesthesia the mortality rate was less than 10 per cent, while similar ligation in conscious animals was followed by an increase in the mortality rate to approximately 40 per cent. From direct and indirect observations on the conscious animals in that series of experiments it was suggested that in addition to the primary ischemic area produced by such ligation other areas of myocardium were rendered ischemic