Transmural ventricular activation during consecutive cycles of sustained ventricular tachycardia associated with
N A Branyas1, M E Cain, J L Cox
1Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri 63110.
Insights
Beat-to-beat analysis of ventricular tachycardia (VT) activation maps is reliable. Single-beat mapping accurately reflects ventricular activation, aiding clinical decisions in patients with sustained monomorphic VT.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Computerized mapping aids intraoperative delineation of ventricular activation during ventricular tachycardia (VT).
- Beat-to-beat reproducibility of isochronic maps for VT has not been previously defined.
- Reliability of single-beat analysis is crucial for accurate intraoperative mapping.
Purpose of the Study:
- To determine the reliability and reproducibility of single-beat isochronic maps.
- To assess beat-to-beat variations in ventricular activation during sustained monomorphic VT.
- To evaluate the clinical utility of single-beat analysis in intraoperative mapping.
Main Methods:
- Analyzed epicardial and transmural ventricular electrograms from 10 patients during sustained monomorphic VT.
- Recorded bipolar electrograms from up to 96 epicardial and 156 transmural sites over 6 consecutive VT cycles.
- Compared local activation time, electrogram duration, and morphology across consecutive beats.
Main Results:
- Isochronic activation maps were reproducible for each patient.
- Mean beat-to-beat variations in local activation times were minimal (epicardial: 1.7 ± 1.7 ms; transmural: 2.04 ± 1.9 ms).
- Electrogram durations showed no significant variation (epicardial: 2.1 ± 1.8 ms; transmural: 1.4 ± 1.9 ms).
- Only two instances of 2:1 conduction failure were observed, both intramurally near the VT origin.
Conclusions:
- Single-beat analysis of ventricular activation during VT is reliable and reproducible.
- Intraoperative computerized mapping using single-beat analysis is expedient for clinical decision-making.
- Transmural ventricular activation during sustained monomorphic VT is consistent, irrespective of electrode site or electrogram duration.
Abstract:
Although computerized mapping has enabled the intraoperative delineation of global ventricular activation from a single complex of ventricular tachycardia (VT), beat-to-beat reproducibility of isochronic maps has not been defined. To determine the reliability of single-beat analysis, epicardial and transmural ventricular electrograms during 6 consecutive VT cycles were analyzed in 10 patients during intraoperative mapping of sustained monomorphic VT. Bipolar electrograms were recorded simultaneously using sock and needle electrodes from up to 96 epicardial and 156 transmural sites. In each patient, at each electrode site, local activation time, electrogram duration and morphology were compared over 6 consecutive beats. A total of 9,816 electrograms were analyzed. For each patient, the isochronic activation map during VT was reproducible. Mean beat-to-beat variations in local epicardial and transmural activation times were only 1.7 +/- 1.7 and 2.04 +/- 1.9 ms, respectively (difference not significant). Moreover, electrogram duration did not vary significantly. Mean variations in epicardial and transmural electrogram durations were 2.1 +/- 1.8 and 1.4 +/- 1.9 ms, respectively (difference not significant). There were only 2 instances of 2:1 conduction failure; both occurred intramurally and adjacent to a site of VT origin. Thus, transmural ventricular activation during sustained monomorphic VT is reproducible regardless of electrode site or electrogram duration. These results demonstrate that analysis of a single beat of VT is a reliable and expedient method to delineate ventricular activation during intraoperative computerized mapping for the purpose of clinical decision-making in patients with sustained monomorphic VT.
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