Successful radiofrequency catheter ablation of an anteroseptal accessory pathway in cardiac dextroposition presenting with aborted sudden cardiac death: a case report

(A) Chest radiograph showing right-sided displacement of the cardiac silhouette. The cardiac chambers and aortic arch are located within the right hemithorax. (B) 12-lead electrocardiogram (ECG) was obtained with the precordial electrodes relocated further rightward from the standard positions. (C) The ECG showed a positive P-QRS complex in lead I and a normal axis, while the shortened PR interval and delta waves in the precordial leads. (D) CARTO 3 electroanatomical map (right anterior oblique [RAO]/left anterior oblique [LAO] projections) depicting the earliest ventricular activation at the anteroseptal tricuspid annulus, adjacent to the tagged His bundle (yellow dots). (E) (Left panel) The CARTO 3 map and intracardiac electrograms demonstrating successful ablation: Earliest activation at the anteroseptal tricuspid annulus (yellow dots), ablation lesions (pink), and the successful lesion (blue). (Right panel) Corresponding pre- and post-ablation EGM/ECGs showing complete elimination of the delta wave.

Figure 1. (A) This electrocardiogram strip demonstrates ventricular fibrillation, as documented by emergency medical services at the moment of defibrillation. (B) This electrocardiogram strip, recorded on arrival to the emergency department, shows findings consistent with atrial fibrillation with pre-excitation.

Figure 2. Chest radiograph in anteroposterior projection demonstrating right-sided position of the cardiac silhouette. Cardiac chambers and the aortic arch are visualized within the right hemithorax (black arrow). Simultaneously, the gastric air bubble can be seen in the left upper abdomen.

Figure 3. Surface 12-lead electrocardiograms showing various precordial-lead and limb-lead configurations. (A) Electrocardiogram recorded using reversed limb leads and right-sided precordial leads based on known dextrocardia (Dextrocardia lead placement). Leads I and aVL display negative QRS complexes, while leads II, III, aVR, and aVF show positive QRS complexes. The precordial leads reveal a shortened PR interval and marked delta waves with an inverted R-wave progression. (B) Electrocardiogram obtained with precordial electrodes shifted further to the right (modified based on chest computed tomography findings, indicating dextroposition rather than dextrocardia). The frontal plane axis is restored to normal, although pre-excitation in the precordial leads remains present.

Figure 4. Fluoroscopy and electroanatomical mapping images during electrophysiological study. (A) Right anterior oblique (RAO 30°) fluoroscopic image showing the duodecapolar catheter positioned along the high right atrium–tricuspid annulus and the His–right ventricular catheter. (B) Anteroposterior (AP) image depicting catheter positions relative to altered anatomy due to cardiac dextroposition. (C) CARTO 3 electroanatomical mapping (right anterior oblique/left anterior oblique projections) illustrating the site of earliest ventricular activation at the anteroseptal tricuspid annulus, adjacent to the mapped His bundle (yellow dots). (D) (Left panel) The CARTO 3 map and intracardiac electrograms confirming successful ablation: earliest activation at the anteroseptal tricuspid annulus (yellow dots), ablation sites (pink), and the effective lesion (blue). (Right panel) Corresponding pre-ablation and post-ablation electrogram (EGM) showing complete resolution of the delta wave.

Figure 5. With the precordial electrodes relocated further to the right, the 12-lead electrocardiograms showed absence of delta waves and demonstrated preserved R/S progression across the precordial leads.