Re-entrant ventricular tachycardia in a postoperative case of tetralogy of Fallot – Ablated successfully under the three-dimensional mapping system

A 47-year-old female underwent cardiac repair for tetralogy of Fallot at the age of 12 years. Subsequently, she was asymptomatic on follow-up. Recently, she presented elsewhere with palpitations and presyncope with documented ventricular tachycardia (VT) having left bundle branch block morphology with inferior QRS axis and late precordial transition. She was reported to have cardioverted and referred to our center for electrophysiology study (EP). She underwent EP study which induced clinical VT which was hemodynamically stable and the mechanism of VT was confirmed as re-entry. With the help of three-dimensional mapping system, VT circuit was identified in the posterior right ventricular outflow tract region between the pulmonary valve and upper end of ventricular septal defect patch. Delivery of radiofrequency energy during VT terminated the tachycardia with no further inducible VT despite aggressive pacing protocols.