Changes in coupling interval of >=100 ms or pacing cycle lengths (600 vs 300 ms) altered QRS morphology in a mean of 4/12 electrocardiographic leads during ventricular pace mapping.
Observational (n=20)
Does varying the coupling interval and pacing cycle length affect QRS morphology during ventricular pace mapping?
During ventricular pace mapping, the coupling interval or cycle length of the template arrhythmia should be matched during pacing to avoid rate-dependent changes in QRS morphology that could confound results.
BACKGROUND: Ventricular pace mapping is performed by comparing the QRS morphology of ventricular paced complexes to that of a template arrhythmia, either a premature ventricular depolarization or a QRS complex during ventricular tachycardia. The objective of this study was to evaluate the effect of coupling interval and pacing cycle length on QRS morphology. METHODS AND RESULTS: The study population consisted of 20 patients (mean age, 38 +/- 16 years) undergoing a clinically indicated electrophysiology procedure. In the first 10 patients, the effect of coupling interval on the morphology of single paced ventricular complexes was evaluated visually and by signal processing techniques. Visually apparent differences in QRS morphology occurred in a mean of 4/12 electrocardiographic leads with a change in coupling interval of > or = 100 ms. In the next 10 patients, the QRS complex morphology during ventricular overdrive pacing at cycle lengths of 600 and 300 ms was found to differ significantly in a mean of 4/12 leads. The QRS morphology during overdrive pacing differed significantly from that of a single paced complex whenever the pacing cycle length differed from the coupling interval of the single paced complex by > 80 ms. CONCLUSIONS: The morphology of single paced QRS complexes may vary, depending on coupling interval, and the QRS morphology during overdrive pacing is affected by the pacing cycle length. During ventricular pace mapping, the coupling interval or cycle length of the template arrhythmia should be matched during pacing. If not, rate-dependent changes in QRS morphology that are independent of the pacing site may confound the results of pace mapping.
Goyal et al. (Sun,) conducted a observational in Patients undergoing a clinically indicated electrophysiology procedure (n=20). Varying coupling intervals and pacing cycle lengths was evaluated on Differences in QRS morphology across 12 electrocardiographic leads. Changes in coupling interval of >=100 ms or pacing cycle lengths (600 vs 300 ms) altered QRS morphology in a mean of 4/12 electrocardiographic leads during ventricular pace mapping.