Regional myocardial metabolism following acute coronary artery occlusion.

Regional measurements of the consequences of coronary artery occlusions indicate myocardial derangements in both the coronary occluded and nonoccluded myocardium. The proximal left anterior descending coronary artery (LAD) was acutely occluded in 34 closed-chest anesthetized dogs through inflation of an intracoronary balloon. Temporary seperation of venous compartments was achieved by means of a balloon catheter placed within the great cardiac vein, and simultaneous blood sampling from both occluded and nonoccluded segments was carried out. Acute coronary occlusion resulted in early cardiac dysfunction which persisted during the subsequent 3 hours of LAD occlusion. Oxygen extraction increased 6-8% in both occluded and nonoccluded zones. Lactate extraction in the nonoccluded segment decreased significantly from 34.4 to 23.7% (P less than 0.05). In the occluded zone, lactate extraction dropped from 35.0 to 7.8% (P less than 0.05). Of the 34 dogs studied, 17 exhibited lactate production in the occluded segment, while 7 dogs also had lactate production in the nonoccluded region. Significant postocclusion myocardial potassium efflux was noted in both zones.