Origgi MS, Gallo Junior L, Godoy RA, Marin-Neto JA, Maciel BC. Universidad de Sao Paulo, Brasil. Arch Inst Cardiol Mex 1990;60(3):241-51. (Published erratum appears in Arch Inst Cardiol Mex 1991;61(1):91). Considering that catheterization of the esophagus is a relatively easy procedure, we studied the electrical transesophageal atrial stimulation in ninety patients (age range 15 to 75 years (mean 42 +/- 9 years). A multipolar electrode catheter was introduced through the nose into the esophagus of each patient and fixed in position at a site where the simultaneous recording of intraesophageal unipolar electrocardiographic derivations showed the greatest P wave potentials. Electrical atrial capture through the esophagus was obtained at frequency values higher than that of the heart, with lower voltages needed for atrial stimulation at the site in which the unipolar recording of the intraesophageal P wave was of highest amplitude. The difference of potential used was between 6 and 30 volts, with the highest values corresponding to patients with megaesophagus, whereas values below 15 volts were tolerated without major discomfort. Electric pulses of more than 10 ms duration did not significantly reduce the intensity of electric current needed to produce the atrial command. The stimulation bipole (area to be stimulated per pole, 0.72 cm2) had an interpolar distance of 22 or 30 mm, our overall experience showing that distances up to 44 mm did not require higher voltages. No cases of esophageal damage or severe arrhythmia were reported due to stimulation. In the present study, programmed transesophageal stimulation proved to be a good option for the evaluation of sinus node function and for the study and reversal of paroxysmal supraventricular tachycardia attacks by a reentry mechanism, representing in some cases an alternative approach for the study of atrioventricular conduction.