Fu H, Lang EP. Hua Hsi I Ko Ta Hsueh Hsueh Pao 1989 Mar;20(1):99-102. In order to assess the diagnostic methods of dual atrioventricular node pathway (DAVNP), we performed transesophageal atrial pacing in 58 patients with palpitation. These patients were classified into two groups, group A comprising 40 patients without broken A-V conduction curve during pacing, compared with group B of 18 patients with broken A-V conduction curve. In our study, both atypical Wenckebach cycle and 3:2 A-V conduction during the increment atrial pacing (IAP) had no significant difference between the two groups (P greater than 0.05). The maximum increments of SR interval in Wenckebach cycle of group A and B during pacing (Wenckebach delta SRmax) were 83.59 +/- 20.92 ms and 125.00 +/- 32.52 ms respectively (P less than 0.001) and at the cut-off point of Wenckebach delta SRmax at 120 ms the specificity and positive predicative value were very high (96.88% and 90.91%), but sensitivity was not so high (71.43%). The minimum increments of RS interval (delta RSmin) in a greater change of SR interval showed a significant difference between the two groups and the specificity and positive predicative value were also high, but the sensitivity was not so high, either (78.57%). We conclude that the diagnostic value of both Wenckebach delta SRmax and delta RSmin, when the SR interval is of greater change during pacing to the DAVNP, is rather significant. As the sensitivity is very low, isolated atypical Wenckebach phenomenon is not as reliable a diagnostic criterion to the DAVNP as previously supposed.