To evaluate the electrocardiographic (ECG) characteristics and radiofrequency catheter ablation (RFCA) efficacy for ventricular arrhythmias (VA) originating from ventricular basal-septum (VBS) areas.

Retrospective analyses of VA originating from VBS confirmed by electrophysiological study were conducted in Fuwai Hospital from January 2015 to May 2018.All the mapping and RFCA procedures were guided by both fluoroscopy and three dimensional mapping systems.The targets were demonstrated through activation and pace mapping.The characteristics of surface 12-lead ECG, efficacy of RFCA were analyzed.

Among 859 consecutive VA cases, 29 (3.4%) were confirmed as origin of VBS (11 cases were left VBS, 18 cases right VBS separately). The ratio of para-His region origin was higher than other areas.After a mean follow up of 21.6±11.7(4-42)months, the overall success rate for RFCA of VA originating from VBS was 84% (24/29), no atrioventricular conduction block occurred.ECG characteristics of right VBS were: QS or W morphology on V₁, the later the originating location, the earlier the precordial transition zone between V₂ and V₃.R wave decrease in Ⅱ, aVF, Ⅲ leads from anterior to posterior septum.ECG characteristics of left VBS were: qR or qr morphology on V₁.Dominant-positive R on precordial leads, rarely s wave in superior VBS.Rs morphology on V₅ and V₆ in mid-posterior VPS.R wave decrease in Ⅱ, aVF, Ⅲ leads from anterior to posterior septum (from R to RS and rS).

The prevalence of VA originating from VBS is relative low, and the ratio of para-His bundle origin is higher than that of other areas.There are distinctive ECG characteristics of VA originating from VBS which guided effectively ablation.

Catheter ablation; Ventricular arrhythmias; Basal-septum areas