Left-Sided Ablation of Ventricular Tachycardia in Adults with Repaired Tetralogy of Fallot: A Case Series
Background—Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in repaired Tetralogy of Fallot (rTOF) focuses on isthmuses in the right ventricle but may be hampered by hypertrophied myocardium or prosthetic material. These patients may benefit from ablation at the left side of the ventricular septum.
Methods and Results—Records from 28 consecutive rTOF patients from two centres, who underwent VT ablation, were reviewed. Ablation targeted anatomical isthmuses containing VT reentry circuits identified by 3D substrate, pace and/or entrainment mapping. A left-sided approach was considered beneficial if (1) right-sided RFCA failed, (2) part of the circuit was mapped to the left side and (3) left-sided RFCA resulted in isthmus transection and prevention of VT induction. In 4/28 patients (52±13 years, 75% male), inducible for 1.5 (quartiles, 1.0 - 2.0) VTs (335±58 msec), left-sided RFCA was performed. In 3 patients RFCA at aortic sites terminated VT related to a septal isthmus and prevented re-induction. In 1 patient, with prior biventricular ICD, diastolic activity was recorded at the left side of the septum in proximity to the His-bundle. RFCA prevented VT re-induction with anticipated complete AV-block. The left-sided approach resulted in complete procedural success (transection of anatomical isthmus and non-inducibility) and freedom of VT recurrence during follow-up (20±15 months) in all patients. Right-sided RFCA failure was likely due to septal hypertrophy in 2, the overlying pulmonary homograft in 1 and overlying VSD patch in 1.
Conclusions—Left-sided RFCA for VTs dependent on septal anatomical isthmuses improves ablation outcome in rTOF.
- Received March 9, 2014.
- Revision received July 14, 2014.
- Accepted July 28, 2014.