Chung DC; Townsend GE; Kerr CR. Anesthesiology 1986, 65(4) p428-31. Stimulation threshold for atrial capture was investigated at varying levels of the esophagus and the relationship between pulse strength and duration was evaluated with respect to atrial capture. Study population consisted of 6 anesthetized patients undergoing gynecological or orthopedic surgery and 5 patients undergoing examination for paroxysmal supraventricular tachycardia. A quadratic relationship was found between depth of catheter insertion (cm) and threshold current (mA), with minimum threshold ranging from 4.6 to 9.3 mA. The stimulus strength-duration relationship showed a rapid decline in threshold current amplitude as pulse duration was increased from 1 to 5 msec, with relatively no change in threshold over the range 5 to 9.9 msec. In conclusion, transesophageal atrial pacing is safe and has few complications. Signs of irritation during pacing in conscious patients (e.g. coughing) are observed with proximal insertion of electrodes. An average depth of insertion of 36 cm and pulse width of 10 msec are recommended, allowing for atrial capture with stimulus current below 15 mA in most patients. (CardioCommand abstract).