Incremental pacing for the diagnosis of complete cavotricuspid isthmus block during radiofrequency ablation of atrial flutter.
BACKGROUND
Complete conduction block of the cavotricuspid isthmus (CTI) reduces atrial flutter recurrences after ablation. Incremental rapid pacing may distinguish slow conduction from complete CTI conduction block.


RESULTS
Fifty-two patients (67 +/- 9 years) undergoing 55 CTI ablation procedures were included. With ablation, double potentials (DPs) separated by an isoelectric line of > or =30 ms were obtained. Incremental atrial pacing (600-250 ms) was performed from coronary sinus (CS) and low lateral right atrium (LLRA). A <20 ms increase in the DPs distance during incremental pacing was indexed as complete CTI block. In 8 patients, an initial <20 ms DPs distance increase was noted; direct complete isthmus block was suggested and no additional ablation performed. In the remaining, the CTI line was remapped for conduction gaps and additional radiofrequency energy pulses applied. Complete block, as indexed by incremental pacing, occurred in 46 of 55 procedures, with one flutter recurrence (follow-up 8 +/- 2 months): DPs interval variation of 116 +/- 20 to 123 +/- 20 ms (CS), P = 0.21; and 122 +/- 25 to 135 +/- 35 ms (LLRA), P = 0.17. The remaining 9 patients (persistent rate-dependent DPs increase) presented 3 flutter recurrences, P = 0.01: DP distance from 127 +/- 15 to 161 +/- 18 ms (CS), P < 0.001; and 114 +/- 24 to 142 +/- 10 ms (LLRA), P = 0.007.


CONCLUSIONS
Incremental pacing distinguishes complete CTI block from persistent conduction. Such identification, accompanied by additional ablation to achieve block, should minimize flutter recurrences after ablative therapy.
Bazan
Victor
V
Electrophysiology Unit, Cardiology Department, Hospital del Mar, IMAS, UAB, Barcelona, Spain. vbazan@imas.imim.es
Martí-Almor
Julio
J
Perez-Rodon
Jordi
J
Bruguera
Jordi
J
Gerstenfeld
Edward P
EP
Callans
David J
DJ
Marchlinski
Francis E
FE
D000368:Aged; D001282:Atrial Flutter / Q000150:complications* / Q000175:diagnosis / Q000601:surgery*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation / Q000009:adverse effects*; D005260:Female; D006327:Heart Block / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014261:Tricuspid Valve; D014682:Vena Cava, Inferior