Double potentials along the ablation line as a guide to radiofrequency ablation of typical atrial flutter

OBJECTIVES The purpose of this study was to determine the characteristics o f double potentials (DPs) that are helpful in guiding ablation within the c avo-tricuspid isthmus. BACKGROUND Double potentials have been considered a reliable criterion of c avo-tricuspid isthmus block in patients undergoing radiofrequency ablation of typical atrial flutter (AFL). However, the minimal degree of separation of the two components of DPs needed to indicate complete block has not been well defined. METHODS Radiofrequency ablation was performed in 30 patients with isthmus-d ependent AFL. Bipolar electrograms were recorded along the ablation line du ring proximal coronary sinus pacing at sites at which radiofrequency ablati on resulted in incomplete or complete isthmus block. RESULTS Double potentials were observed at 42% of recording sites when ther e was incomplete isthmus block, compared with 100% of recording sites when the block was complete. The mean intervals separating the two components of DPs were 65 +/- 21 ms and 135 +/- 30 ms during incomplete and complete blo ck, respectively (p < 0.001). An interval separating the two components of DPs (DP1-2 interval) < 90 ms was always associated with a local gap, wherea s a DP1-2 interval greater than or equal to 110 ms was always associated wi th local block. When the DP1-2 interval was between 90 and 110 ms, an isoel ectric segment within the DP and a negative polarity in the second componen t of the DP were helpful in indicating local isthmus block. A DP1-2 interva l greater than or equal to 90 ms with a maximal variation of 15 ms along th e entire ablation line was an indicator of complete block in the cavo-tricu spid isthmus. CONCLUSIONS Detailed analysis of DPs is helpful in identifying gaps in the ablation line and in distinguishing complete from incomplete isthmus block in patients undergoing radiofrequency ablation of typical AFL. (C) 2001 by the American College of Cardiology.