Deng ZW. Chung Hua I Hsueh Tsa Chih 1989 Feb;69(2):66-8. A method of transesophageal atrial activation sequence determination was created by using simultaneous recording with two unipolar esophageal leads and V1, as well as by the bipolar esophageal lead. Based on the assumption that the peak of P wave in the uni-polar esophageal lead (PE) reflects roughly the activation time of the left posterior atrium wall, and so as to the peak of P wave in V1 (PV1) for the right anterior atrium wall, four items were used as indicators of atrial activation sequence: 1. PV1-PE interval; 2. PEp-PED interval (measured from the peak of P wave in the proximal to that in the distal esophageal lead); 3. Morphology of the bipolar esophageal P wave (PEB); 4. PEp-PED-PV1 sequence; In 190 cases having undergone transesophageal atrial pacing with sinus rhythm, PV1-PE measurement was 28.0 +/- 13.9 ms and PEp-PED was 3 +/- 12 ms. During atrioventricular reciprocating tachycardia in 17 cases with type-A preexcitation and 18 cases with left-sided concealed accessory pathway, PV1-PE was -63.3 +/- 19.0 and -63.7 +/- 27.5 ms, with PEp-PED -17.1 +/- 22.0 and 16.4 +/- 16.7 ms respectively. Transesophageal atrial activation sequence determination is helpful in raising the diagnostic accuracy for arrhythmia.