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KG is a 38-year-old woman with the diagnosis of transposition of the great arteries (TGA). She underwent an atrial switch operation at age 2 (Figure 13-1). Her first episode of atrial flutter occurred at age 11 and was refractory to antiarrhythmic drug therapy with multiple cardioversions and ultimately required permanent pacemaker implant to support drug therapy. A prior electrophysiologic (EP) study and radiofrequency ablation (RFA) was unsuccessful. She recently had an episode of atrial flutter while taking sotalol 120 mg bid and metoprolol 12.5 mg daily. Her symptoms abruptly began with exertion and including dizziness and dyspnea associated with ventricular rates greater than 200 bpm (Figure 13-2). She underwent cardioversion and beta-blocker dose titration but unfortunately could not tolerate higher beta-blockade. She was subsequently referred for repeat EP study. Two separate arrhythmias were induced, an atrial tachycardia that had not been seen clinically (Figure 13-3) and atrial flutter (Figures 13-4 and 13-5). Mapping was initially performed on the systemic venous side and the atrial tachycardia location was identified and ablated. In order to map the atrial flutter a transbaffle puncture was performed to access the tricuspid valve and the pulmonary venous side (Figure 13-6). Entrainment mapping was used to identify the circuit (Figure 13-5). The atrial flutter was successfully ablated (Figure 13-7) by placing lesions from the inferior vena cava (IVC) to the baffle on the systemic venous side and then from the baffle to the tricuspid valve on the pulmonary venous side (Figure 13-8). She has since had no recurrence of her atrial flutter.
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