Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways

Annibale Sandro Montenero, Filippo Crea, Maria Grazia Bendini, Gemma Pelargonio, Anselma Intini, Maria Luisa Finocchiaro, Francesco Biscione, Fabio Pigozzi, Fulvio Bellocci, Paolo Zecchi

Research output: Contribution to journalArticlepeer-review


Background: Catheter oblation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson- White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. Methods and Results: One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in <10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) 'unipolar' electrogram was recorded, the following time intervals were measured: (1)from the onset of the atrial to the onset of the K potential (A-K); (2)from the onset of the delta wave to the onset of the K potential (delta-K); and (3)from the onset of the K potential to the onset of the ventricular deflection (K-V). During unsuccessful versus successful attempts, A-K (51 ± 11 ms vs 28 ± 8 ms, P <0.0001 for left pathways [LPs]; and 44 ± 8 ms vs 31 ± 8 ms, P <0.02 for right pathways [RPs]) and delta-K intervals (2 ± 9 ms vs -18 ± 10 ms, P <0.0001 for LPs; and 13 ± 7 ms vs 5 ± 8 ms, P <0.02 ms for RPs) were significantly longer. Conclusions: Short A-K interval (<40 ms), and a negative delta-K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A-K and delta- K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A-K and delta-K interval.

Original languageEnglish
Pages (from-to)905-912
Number of pages8
JournalPACE - Pacing and Clinical Electrophysiology
Issue number6
Publication statusPublished - 1996


  • catheter ablation
  • electrophysiology
  • mapping
  • Wolff-Parkinson-White syndrome

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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