Effects of Sustained Ventricular Pacing During Cardioplegic Arrest on Global and Regional Postischemic Left Ventricular Performance

Although coronary artery bypass graft surgery is frequently performed in patiejits with permanent ventricular pacemakers, the effects of pacemaker generator stimuli during cardioplegic arrest are unknown. This study was undertaken to detennine whether, during cardioplegic arrest in the presentee of a coronary occlusion, pacemaker stimuli accentuate postischemic LV damage. Twelve pigs were placed on cardiopulmonary bypass and subjected to 80 min ofischemic arrest with multiple doses of crystalloid potassium crystalloid caidioplegia supplemented with topical and systemic (28C) hypothermia. During arrest, the mid LAD was occluded with a snare that was released upon reperfusion. In all animals, epicardial ventricular pacing wires were placed and capture was confirmed. In 6 pigs, pacing was instituted prior to ischemic arrest and continued throughout the ischemic and postischemic periods. Six other pigs were not paced and served as controls. Pacemaker stimuli during arrest had no effect on LV temperature. There was no difference in postischemic Lt mass, compliance curves, wall‐motion scores, or stroke xvork itidex between the paced and nonpaced hearts. We conclude that sustained pacemaker stimuli during cardioplegic arrest does not impair global and regional postischemic LV function.