R-wave synchronised atrial pacing in pediatric patients with postoperative junctional ectopic tachycardia: the atrioventricular interval investigated by computational analysis and clinical evaluation.

BACKGROUND: R-wave synchronised atrial pacing is an effective temporary pacing therapy in infants with postoperative junctional ectopic tachycardia. In the technique currently used, adverse short or long intervals between atrial pacing and ventricular sensing (AP-VS) may be observed during routine clinical practice.

OBJECTIVES: The aim of the study was to analyse outcomes of R-wave synchronised atrial pacing and the relationship between maximum tracking rates and AP-VS intervals.

METHODS: Calculated AP-VS intervals were compared with those predicted by experienced pediatric cardiologist.

RESULTS: A maximum tracking rate (MTR) set 10 bpm higher than the heart rate (HR) may result in undesirable short AP-VS intervals (minimum 83 ms). A MTR set 20 bpm above the HR is the hemodynamically better choice (minimum 96 ms). Effects of either setting on the AP-VS interval could not be predicted by experienced observers. In our newly proposed technique the AP-VS interval approaches 95 ms for HR > 210 bpm and 130 ms for HR < 130 bpm. The progression is linear and decreases strictly (- 0.4 ms/bpm) between the two extreme levels.

CONCLUSIONS: Adjusting the AP-VS interval in the currently used technique is complex and may imply unfavorable pacemaker settings. A new pacemaker design is advisable to allow direct control of the AP-VS interval.