Kates RA, Zaidan JR, Kaplan JA. Anesth Analg 1982 61(9):781-5. The use and safety of the esophageal electrocardiogram for detection and diagnosis of dysrhythmias or ischemia during anesthesia was compared with the conventional electrocardiogram using leads II and V5 in 20 patients undergoing coronary artery bypass graft surgery. Using an intra-atrial electrocardiogram as the standard to provide detection and definitive diagnosis of dysrhythmias, the correct diagnosis from leads II and V5 was made in 53.8% and 42.3% of cases, respectively, whereas 100% of the dysrhythmias were properly diagnosed from the esophageal electrocardiogram (p less than 0.05). In two patients, the presence of a significant dysrhythmia was not detected using standard leads II and V5 alone. Large, distinct P waves, resulting from the proximity of the esophageal lead to the left atrium, clearly established the temporal relationship between atrial and ventricular depolarization. Posterior myocardial ischemia was diagnosed in one patient by ST-segment elevation in the esophageal electrocardiogram, whereas leads II and V5 did not demonstrate ischemic changes. No complications were encountered during the study. The esophageal lead is safe, simple to use, and provides valuable information for detection or diagnosis of dysrhythmias and myocardial ischemia during anesthesia.