Figure 34-8 In the cardioesophagoscope, the esophageal leads are made of plastic. The electrocardiographic (ECG) wires are connected to the right and left arms, with lead I selected on the electrocardiographic monitor. (Adapted from Narang J, Thys DM: Electrocardiographic monitoring. In Ehrenwerth J, Eisenkraft JB [eds]: Anesthesia Equipment: Principles and Applications. St. Louis, Mosby-Year Book, 1992, p 284.)