Successful Ablation of Cavo-tricuspid Isthmus Dependent Atrial Flutter in a Patient with Senning Operation

Correspondence To the Editor: Intraatrial reentry tachycardia (IART) has been reported to occur in 2% to 10% of Mustard and Senning patients at 10 years' follow‑up. We reported a case in which the cavo‑tricuspid isthmus (CTI) in both the systemic venous atrium (SVA) and pulmonary venous atrium (PVA) was necessarily targeted in a patient following Senning operation. The patient was a 26‑year‑old man who was diagnosed d‑transposition of the great arteries and accepted Senning operation at 14 months of age. At the age of 6 years, he underwent permanent pacemaker implantation for sinus bradycardia. In recent 2 years, he developed persistent drug refractory atrial flutter with the highest ventricular rate of 210 beats/min. and was referred for an electrophysiological study and ablation procedure in our center. A 6‑French octapolar deflectable catheter was deployed in the left atrial appendage via the right femoral vein for activation reference. An atrial flutter with a 240 ms tachycardia cycle length (TCL) was recorded. The ostium of the coronary sinus was kept in the PVA in this patient. Thus, the CTI was partitioned in two, with the inferior vena cava (IVC) portion on the SVA and the tricuspid valve (TV) portion on the PVA. Electroanatomic mapping was initiated in the more accessible SVA via right femoral vein access. The activation mapping showed a focal activation pattern with a total activation time <50% of the TCL. The PVA was mapped thereafter. A retrograde access via the femoral artery, aorta, right ventricle, and TV was used. The activation sequence achieved in PVA showed a macroreentry rotating around the TV clockwise. Entrainment pacing at multiple sites around the TV [Figure 1] confirmed the circuit with the postpacing interval approximating the TCL (≤30 ms difference). This patient had developed a significant degree of TV insufficiency, we met great difficulty in stabilizing the catheter when ablating the CTI in PVA, so we tried the transbaffle approach to access the PVA. The transbaffle puncture was made by a transseptal needle which was directed superiorly and anteriorly (12 o'clock). The needle traversed into the PVA through the superior portion of the baffle limb [Figure 2], an 8.5‑French sheath was then advanced in the PVA through a guidewire. A linear radiofrequency (RF) lesion bridging the large scar area on the free wall of the PVA to the tricuspid annulus terminated the tachycardia. A 20‑electrode mapping catheter (Halo, Biosense Webster, Inc.) was positioned in …