Background: Most right ventricular arrhythmias (VA) originate from the outflow tract. Experiences of VA arising from the basal septum of the right ventricle (RV) are limited. We aimed to describe the ablation procedure and results, focusing on the characteristics and clinical significance of junctional rhythm (JR) appearing during radiofrequency application.
Methods and results: Among 86 consecutive patients undergoing radiofrequency ablation for VA from the RV, 12 (14%) (mean age, 71 ± 7 years) had their origin in the basal septum of the RV defined as the region from 1 to 5 o'clock of the tricuspid annulus (TA) in the left anterior oblique view and extending anteriorly from the TA to 2 cm. A mean QRS duration of VA was 137 ± 8 msec with normal (10/12, 83%) or left-deviated axis (2/12, 17%). Five patients (41%) had structural heart diseases including three dilated cardiomyopathies. Radiofrequency energy was applied to the sites showing the earliest activation during VA and/or best pacemap. Complete elimination of VA was achieved in 11 (92%) patients. The successful ablation site was 12 ± 4 mm away from the His-bundle electrogram recording site. Among 11 patients with successful ablation, 10 (91 %) exhibited JR (mean cycle length, 638 ± 172 ms) during ablation without subsequent atrioventricular conduction disturbance (AVCD) except for one showing high-rate JR (181 beats/min) and transient AVCD. All these patients were free from VA during 32 ± 21 months.
Conclusions: VA originating from the basal septum of the RV can be ablated effectively. JR appears in most cases without causing AVCD, unless the rate is high.
Keywords: Catheter ablation; His-bundle; Junctional rhythm; Right ventricle; Tricuspid annulus; Ventricular arrhythmia.