Bipolar Ablation of Ventricular Tachycardia in a Patient After Atrial Switch Operation for Dextro-Transposition of the Great Arteries

Abstract

A 39-year-old man with atrial switch repair (Mustard baffle) and transpulmonary resection of infundibular muscle for dextro-transposition of the great arteries and subpulmonary stenosis was referred for ablation of a drug-refractory monomorphic ventricular tachycardia (VT). Before the ablation, the patient underwent multidetector CT to detect anomalous coronary anatomy (Figure 1A–1C) and contrast-enhanced MRI (CE-MRI) to determine the extent of scar after surgical resection. CE-MRI showed late enhancement in the basal interventricular septum extending toward aortic sinus 2 (origin of the circumflex artery) (Figure 1D and 1E). During the ablation procedure, both multidetector CT and CE-MRI-derived images were integrated with the electroanatomical maps. VT was induced, and diastolic activity could be recorded at the aortic sinus 2 and at the opposing site in the right ventricle (RV). There was no capture when high-output pacing at these sites was performed to entrain the VT. Irrigated-tip radiofrequency (RF) delivery resulted in slowing of the VT when applied from the aortic sinus site (up to 40 W; flow rate, 20 mL/min) and consecutive late termination when RF was delivered from the RV site (up to 50 W; flow rate, 30 mL/min). Figure 1. MDCT and CE-MRI images. A , The RV is connected to the AO. The LAD and the RCA have a common ostium in sinus 1, whereas the CX has a separate ostium in sinus 2. B , The PVs are connected to the RA, and the VCS to the Mustard baffle, directing blood to the LV. C , The poststenotic dilation of the PT is clearly visible. The infundibular septum is indicated by white arrowheads. D and E , The 3D reconstruction of the CE-MRI-derived scar, with red indicating core scar and yellow, border zone scar. Note the potential anatomic isthmus bordered by aortic sinus 2 and a scar in …