Characteristics of ventricular tachycardia arising from the inflow region of the right ventricle

IntroductionVentricular tachycardia (VT) arising from the right ventricular inflow (RVI) region is uncommon. There is minimal literature on the clinical and electrocardiographic characteristics of RVI VT.MethodsA retrospective analysis of patients with RVI VT who underwent electrophysiology study between 2006 and 2011 was performed. Patients with structural heart disease (including arrhythmogenic right ventricular dysplasia) were excluded.ResultsSeventy patients underwent an electrophysiology study for VT arising from the right ventricle during the study period. Nine patients (13%) met the inclusion criteria for RVI VT and were the subject of this analysis. The median age was 46 years (range, 14-71), and VT cycle length was 295 milliseconds (range, 279-400 milliseconds). All VTs had an left bundle-branch block morphology. An inferiorly directed QRS axis was noted in 7 (78%) of 9 patients and a left superior axis in 2 (22%) of 9 patients. A QS or rS pattern was noted in all patients in aVR and V1. A transition from S to R wave occurred in V3 to V5 in all patients, with 78% of the patients transitioning in V4 or V5. Ablation was attempted in 8 (89%) of 9 patients and was successful in 6 (67%) of 9 patients. Ablation was limited in all unsuccessful patients due to the proximity to the His and risk of complete heart block.ConclusionsElectrocardiographic findings of a left bundle-branch block with a normal QRS axis, QS or rS patterns in aVR and V1, and late S to R transition (V4/V5) are commonly found in RVI VT. Because of the proximity to the His, ablation of RVI VT may be more challenging than that of right ventricular outflow tract VT.