What is the clinical evidence from this study?

Study design: Observational. Population: Patients after radiofrequency ablation for reentrant tachycardias (n=50). Intervention: Differential pacing technique vs. Previously described criteria for isthmus block. Primary outcome: Sensitivity, specificity, and predictive values for linear block.

What question did this study set out to answer?

This research aims to develop a technique for distinguishing between complete linear conduction block and persistent conduction through an ablation line.

September 26, 2000Open Access

Differential Pacing for Distinguishing Block From Persistent Conduction Through an Ablation Line

Key Result

Differential pacing accurately distinguished complete linear block from persistent conduction with 100% sensitivity, 75% specificity, 94% positive predictive value, and 100% negative predictive value.

Key Points

This research aims to develop a technique for distinguishing between complete linear conduction block and persistent conduction through an ablation line.
Prospective evaluation of cavotricuspid isthmus conduction in 50 patients post-radiofrequency ablation.
Distal and proximal bipoles of a quadripolar catheter were stimulated to assess conduction at the ablation line.
Timing of local potentials was analyzed to determine presence of block versus persistent conduction.
Initial component timing was delayed by an average of 19±9 ms after complete isthmus block.
Terminal component timing was advanced by 13±8 ms after block, while delayed by 12±9 ms in persistent conduction.
Sensitivity was 100%, specificity was 75%, and predictive values were 94% for positive and 100% for negative.

Study Design

Type

Observational (n=50)

PICO

Population

Patients after radiofrequency ablation for reentrant tachycardias (n=50)

Intervention / Comparator

Differential pacing technique vs Previously described criteria for isthmus block

Primary Outcome

Sensitivity, specificity, and predictive values for linear block

Abstract

BACKGROUND: Because complete linear conduction block is necessary to minimize the recurrence of reentrant tachycardias such as typical atrial flutter, we investigated a simple technique to recognize a persistent gap or complete linear block. METHODS AND RESULTS: We prospectively evaluated cavotricuspid isthmus conduction in 50 patients (age 63+/-8 years, 43 men) after radiofrequency ablation. The distal and proximal bipoles of a quadripolar catheter placed close to the ablation line were successively stimulated during recording from the ablation line. We hypothesized that because the initial and terminal components of local potentials reflected activation at the ipsilateral and contralateral borders of the ablation lesion, a change to a more proximal pacing site without moving the catheter would prolong the stimulus to the initial component timing, whereas the response of the terminal component would depend on the presence of block or persistent conduction. A shortening or no change in timing of the terminal component would indicate block, whereas lengthening would indicate persistent gap conduction. The results were compared with previously described criteria for isthmus block. Ninety-two sites were assessed: 17 before and 75 after the achievement of complete isthmus block. The timing of the initial component was delayed by 19+/-9 ms, and the terminal component was advanced by 13+/-8 ms after block and delayed by 12+/-9 ms in case of persisting conduction. The sensitivity, specificity, and positive and negative predictive values for linear block were 100%, 75%, 94%, and 100%, respectively. CONCLUSIONS: An accurate assessment of isthmus block or persistent isthmus conduction is possible with this technique of differential pacing.