Right Bundle Branch Area Pacing in a Patient with Congenitally Corrected Transposition of the Great Arteries Using Three-dimensional Electroanatomic Mapping

DOI: 10.19102/icrm.2025.16012

SERKAN CAY, MD,¹ HANDE CETIN, MD,¹ and SERKAN TOPALOGLU, MD¹

¹Division of Arrhythmia and Electrophysiology, Department of Cardiology, University of Health Sciences, Ankara City Hospital, Ankara, Turkey

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ABSTRACT. A 35-year-old man with congenitally corrected transposition of the great arteries (ccTGA) and prior ventricular septal defect repair developed pacing-induced cardiomyopathy after 30 years of single-chamber VVI pacemaker use. Right bundle branch area pacing (RBBAP) was chosen for device upgrade due to its potential benefits over conventional cardiac resynchronization therapy. Advanced three-dimensional electroanatomic mapping was employed to navigate a synthetic patch from previous surgery and guide mid-septal electrode placement. Successful RBBAP was achieved with optimal parameters, complemented by atrial and defibrillator lead implantation. At 12 months, the patient showed improved ejection fraction (from 30% to 40%) and stable electrocardiographic results. This case illustrates the role of RBBAP and advanced mapping in addressing complex structural and conduction abnormalities in ccTGA.

KEYWORDS. Corrected transposition, electroanatomic mapping, right bundle branch, pacing.

The authors report no conflicts of interest for the published content. No funding information was provided.
Manuscript received May 23, 2024. Final version accepted August 9, 2024.
Address correspondence to: Serkan Cay, MD, Division of Arrhythmia and Electrophysiology, Department of Cardiology, University of Health Sciences, Yuksek Ihtisas Cardiovascular Building, Ankara City Hospital, Bilkent, 06800 Cankaya, Ankara, Turkey. Email: cayserkan@yahoo.com.

Case presentation

A 35-year-old man, dependent on a pacemaker, with congenitally corrected transposition of the great arteries (ccTGA) (situs solitus) and a previously operated large ventricular septal defect, has had a VVI-mode single-chamber permanent pacemaker implanted for 30 years post-surgery. The initial implantation involved left-sided morphological right ventricular epicardial single-electrode unipolar pacing for 10 years. Subsequently, transvenous right-sided endocardial right-sided morphological left ventricular apical pacing was performed due to dysfunction of the epicardial electrode. He was referred to our division for a device upgrade due to pacing-induced cardiomyopathy of the left-sided morphological right ventricle. Given its inherent advantages over conventional cardiac resynchronization therapy, we opted for conduction system pacing using the right bundle branch area pacing (RBBAP) strategy. Due to a previous ventricular septal defect operation involving the use of a synthetic patch, three-dimensional electroanatomic mapping was performed before placing the pacing electrode to accurately locate the site of ventricular septal penetration. Using the EnSite™ X EP System (Abbott, Chicago, IL, USA) with omnipolar technology and the Advisor™ HD Grid Mapping Catheter (Abbott), we conducted three-dimensional mapping of the right and left heart structures. This mapping revealed a clear identification of the patch area, which manifested as a scar in the basal septal regions of both ventricles without any discernable retrograde His- or left-bundle potentials (Figures 1A–1E, Videos 1–4).

Following this, an active-fixation pacing electrode (Solia S60; Biotronik, Berlin, Germany) was introduced from the left axillary vein through a pre-shaped delivery catheter (Selectra 3D; Biotronik) toward the morphological left ventricular side of the septum. Using a unipolar configuration, the pacing electrode was connected to both the pace/sense analyzer and the EnSite™ X EP System. By switching the electrophysiology mode to NavX™ (Abbott), the tip of the pacing electrode became visible in the preformed three-dimensional maps, appearing as a movable tag. With the assistance of both three-dimensional maps and fluoroscopy, we successfully achieved mid-ventricular septal placement of the pacing electrode just under the scar/patch area. Subsequent clockwise rotations of the pacing electrode from the shaft facilitated deep penetration toward the subendocardial region of the left side of the septum (Figures 1F–1H, Videos 5 and 6). Unipolar pacing confirmed the capture of fibers of the right bundle branch, displaying a right bundle branch block morphology, negative concordance in the inferior leads, an R-wave peak time of 57 ms in lead V6, and an interpeak delay of 69 ms between leads V1 and V6. The QRS changes resulting in RBBAP were observed as the septal pacing electrode started from the entry site on the morphological left ventricular septal side, progressed first into the deep septal area, and then captured the conduction system on the morphological right ventricular septal side (Figure 2). Pacing impedance and capture threshold were measured as 590 Ω and 0.9 V, respectively.

Following this, an active-fixation electrode was implanted into the right atrial appendage, and it was also visible in the three-dimensional map in a unipolar configuration, appearing as a movable tag (Figure 1I, Video 7). Finally, a DF-4 single-coil defibrillator electrode was implanted in the morphological left ventricle (Video 8). A cardiac resynchronization therapy device was also implanted, with the atrial port connected to the atrial lead, the left ventricular port connected to the septal electrode, and the right ventricular sense/pace and defibrillator ports connected to the respective proximal tips of the defibrillator electrode (Figure 1J, Video 9). Left ventricular–only pacing with the dual-chamber configuration was selected to enhance battery longevity. The patient declined extraction of the older pacing electrode, citing inherent risks, and thus, the electrode and the pulse generator were left in situ. At the 12-month follow-up, the ejection fraction had improved from the initial 30% before the upgrade procedure to 40%, and electrocardiography at this time showed the same findings as electrocardiography at implantation (Figure 3). The gross anatomy of structural heart disease, the conduction system, and all implanted electrodes are seen in Figure 4.

Discussion

A significant proportion of patients with ccTGA develop dysfunction over time in the morphological right ventricle connected with systemic arterial circulation, typically manifesting during the fourth and fifth decades of life.¹ Additionally, long-term pacing from the apex of the morphological left ventricle can adversely contribute to this process by causing dyssynchrony. In our relatively young patient, both conditions require consideration; although the ejection fraction has improved with conduction system pacing, complete normalization remains elusive. Optimal medical therapy for heart failure is also recognized to enhance ventricular dysfunction. Furthermore, according to our patient’s medical history, he has been receiving guideline-directed medical therapy, including newly introduced medications for heart failure, since the onset of symptoms of heart failure and determination of low ejection fraction.

Reference

1. Filippov AA, Del Nido PJ, Vasilyev NV. Management of systemic right ventricular failure in patients with congenitally corrected transposition of the great arteries. Circulation. 2016;134(17):1293–1302. [CrossRef] [PubMed]