Ventricular Arrhythmias Arising from the Left Ventricular Outflow Tract below the Aortic Sinus Cusps: Mapping and Catheter Ablation via Transseptal Approach and Electrocardiographic Characteristics
Background—VA originating from the anterosuperior left ventricular outflow tract (LVOT) represents a challenging location for catheter ablation. This study investigates mapping and ablation of ventricular arrythmias (VA) from anterosuperior LVOT via a transseptal approach.
Methods and Results—This study included 27 patients with symptomatic VA, in whom 13 patients had previous failed ablations. LVOT endocardial 3D-mapping via retrograde transaortic and antegrade transseptal approachs were performed. Previous ECG markers for procedure failure were analyzed. In all patients, earliest activation with low-amplitude potentials was identified at the antero-superior LVOT 5.1±2.8mm below the aortic cusp and preceded QRS onset by 39.5±7.7ms only via an antegrade transseptal approach using a 'reversed S-curve'. In all patients, pace mapping failed to demonstrate perfect QRS morphology match. The anatomical location was below the left coronary cusp (LCC) in 16, below the LCC/right coronary cusp (RCC) junction in 8, and below the RCC in 3 patients. Radiofrequency (RF) energy resulted in rapid disappearance of VAs in all patients. ECG analysis showed aVL/aVR Q-wave amplitude ratios >1.4 in 7, III/II R-wave amplitude ratios >1.1 in 10, and Peak deflection index >0.6 in 11 patients. There were no complications or clinical VA recurrence during a mean follow-up of 8.4±2.5 months.
Conclusions—The anterosuperior LVOT can be reached via a transseptal approach with a reversed S-curve of the ablation catheter. The rapid effect from RF energy indicates that the VA is most likely located under the endocardium. Also, previous ECG markers for procedure failure need further investigation.
- Received January 30, 2014.
- Revision received March 28, 2014.
- Accepted March 29, 2014.