IMMEDIATE HEMODYNAMIC EFFECTS OF ACUTE CORONARY OCCLUSION AND THEIR MODIFICATION BY ANESTHESIA

Biplane cineangiography was used to study the effects of an acute reversible circumflex artery occlusion by an implanted exteriorized polyethylene snare in the intact anesthetized dog. Occlusion of the left circumflex coronary artery produced an increase in end-diastolic (43 to 58 ml.) and end-systolic volumes (19 to 37 ml.) in 12 studies. Ejection fraction fell (57 to 36 per cent), whereas stroke volume was often unaltered. A regional loss of contractility in the myocardium supplied by the occluded artery was observed cineangiographically as was late systolic mitral insufficiency, probably as a result of papillary muscle dysfunction. Because different anesthetics produced different control states, the influence of two anesthetics on the hemodynamic response to occlusion were compared. The circumflex artery occlusion with chloralose-urethane anesthesia resulted in a fall in heart rate (149 to 131/min.) and mean blood pressure (134 to 98 mm. Hg) and a rise in left ventricular end-diastolic pressure (9 to 13 mm. Hg). With chloralose-morphine there was a rise in heart rate (84 to 103/min.) and little change in blood pressure (108 to 106 mm. Hg) or left ventricular end-diastolic pressure (6 to 8 mm. Hg). The causes of these differences require further investigation. It is emphasized that when anesthesia cannot be avoided in experimental physiology, the results of the experiment should be carefully reviewed in terms of the anesthetic used. © 1968.