Key result
Mechanical termination identifies effective RVOT ablation targets, linked to ~6 ms earlier local activation.
Why the study?
Mechanical interruption of idiopathic ventricular arrhythmias originating in the right ventricular outflow tract has not been described systematically.
Does mechanical termination during mapping indicate effective radiofrequency ablation sites in patients with idiopathic RVOT arrhythmias?
Observational (n=18)
Does mechanical termination during mapping indicate effective radiofrequency ablation sites in patients with idiopathic RVOT arrhythmias?
Absolute Event Rate: -31% vs -25%
p-value: p=0.04
Mechanical termination of RVOT arrhythmias during mapping is a reliable indicator of an effective ablation site.
Mechanical pressure may interrupt RVOT arrhythmias during mapping; leaves open diagnostic utility pending larger prospective studies.
BACKGROUND: Termination of ventricular tachycardia (VT) by mechanical pressure has been described for fascicular and postinfarction VT. Mechanical interruption of idiopathic ventricular arrhythmias (VT/premature ventricular complexes [PVCs]) arising in the right ventricular outflow tract (RVOT) has not been described in systematic fashion. METHODS: Eighteen consecutive patients (13 females, age 49 +/- 13 years, ejection fraction 0.55 +/- 0.12) underwent mapping and ablation of RVOT VT or PVCs. In 7 patients, 9 distinct VTs (mean cycle length 440 +/- 127 ms), and in 11 patients, 11 distinct PVCs originating in the RVOT were targeted. Mechanical termination was considered present if a reproducibly inducible VT was no longer inducible or if frequent PVCs suddenly ceased with the mapping catheter at a particular location. Endocardial activation time, electrogram characteristics, and pace-mapping morphology were assessed at this location. Radiofrequency energy was delivered if mechanical termination was observed. RESULTS: All targeted arrhythmias were successfully ablated. In 7 of 18 patients (39%), catheter manipulation terminated the arrhythmia with the mapping catheter located at a particular site. Local endocardial activation time was earlier at sites of mechanical termination (-31 +/- 7 ms) compared with effective sites without termination (-25 +/- 3 ms, P = 0.04). The 10-ms isochronal area was smaller in patients with mechanical interruption (0.35 +/- 0.2 cm(2)) than in patients without mechanical termination (1.33 +/- 0.9 cm(2), P = 0.01). At all sites susceptible to mechanical trauma, the pace map displayed a match with the targeted VT/PVC. All sites where mechanical termination of VT or PVCs occurred were effective ablation sites. CONCLUSIONS: Mechanical suppression at the site of origin of idiopathic RVOT arrhythmias frequently occurs during the mapping procedure and is a reliable indicator of effective ablation sites. Mechanical termination of RVOT arrhythmias may be indicative of a more localized arrhythmogenic substrate.
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Kühne et al. (2009) conducted an observational in Idiopathic ventricular arrhythmias originating in the right ventricular outflow tract (RVOT) (n=18). Mechanical termination of arrhythmia during mapping vs. Effective ablation sites without mechanical termination was evaluated on Local endocardial activation time (p=0.04). Mechanical termination of RVOT arrhythmias occurred in 39% of patients, with these sites showing earlier local endocardial activation times (-31 vs -25 ms, P=0.04) and serving as effective ablation targets.
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