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

Introduction: Ventricular 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. Methods: A 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. Results: Seventy 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 V ₁. A transition from S to R wave occurred in V ₃ to V ₅ in all patients, with 78% of the patients transitioning in V ₄ or V ₅. 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. Conclusions: Electrocardiographic findings of a left bundle-branch block with a normal QRS axis, QS or rS patterns in aVR and V ₁, and late S to R transition (V ₄/V ₅) 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.