Non-contact mapping and linear ablation of the left posterior fascicle during sinus rhythm in the treatment of idiopathic left ventricular tachycardia

Abstract

The reentry circuit of idiopathic left ventricular tachycardia (ILVT) has been demonstrated to be confined to the left posterior Purkinje network. We hypothesized that mapping and linear ablation of the left posterior fascicle (LPF) during sinus rhythm guided by non-contact mapping can effectively modify the arrhythmogenic substrate in patients with ILVT and abolish the tachycardia. Six patients with ILVT, consisting of one case in which conventional mapping failed three times, one recurrent case, one non-inducible case and three common cases, were included in the study. After a three-dimensional endocardial geometry of the left ventricle (LV) was created, the conduction system in the LV was mapped during sinus rhythm using a filter setting of 8 Hz. The His bundle area, left bundle branch, fascicles and sinus breakout point (SBO) were mapped in detail and tagged as special landmarks in the geometry. A linear lesion was placed perpendicular to the wave front propagation direction of the LPF, 1 cm above the SBO. There was a small Purkinje potential preceding the ventricular activation at its starting and ending point. The mean tachycardia cycle length of ILVT in this study was 340.3±51.4 ms. After a mean of 5.5±1.6 radiofrequency deliveries, the clinical tachycardias could not be induced and the 12-lead surface ECG showed right QRS axis deviation (mean 39.7±26.0 degrees) in all patients. The total procedure time was 160.0±32.2 min with fluoroscopic time of 26.0±6.8 min. No ILVT was inducible during control stimulation, and none recurred during a mean follow-up of 13.0±4.8 months. Mapping and linear ablation of the Purkinje network in LPF area guided by non-contact mapping is an effective and safe treatment of ILVT with radiofrequency energy, especially for those ILVTs which were unsuccessfully treated by conventional means or were non-inducible or non-sustained during the procedure.