Cardiac resynchronization therapy by pacing the right ventricular dorsal site of inflow and anterior outflow for congenitally corrected transposition of the great arteries: a case report.

Background: Evidence regarding cardiac resynchronization therapy (CRT) for congenitally corrected transposition of the great arteries (ccTGA) is insufficient. The timing to perform CRT and optimal pacing sites have not been systematically studied. We performed CRT for ccTGA with a complete atrioventricular block (CAVB) by pacing the dorsal site of right ventricular inflow (dRVI) and anterior RV outflow tract (aRVOT). Case summary: We examined a man aged 19 with ccTGA (S.L.L) and Ebstein anomaly, who developed CAVB at 19. We decided to implant CRT rather than a conventional pacemaker for preventing right ventricular (RV) dysfunction. At first, we implanted transvenous pacing leads on the right atrium and dRVI via the coronary sinus. During dRVI pacing, the most delayed contraction site was the aRVOT by the echocardiographic speckle tracking and the electrophysiological study. Accordingly, we implanted additional epicardial lead in the aRVOT and completed the implantation of CRT. After the CRT, the QRS duration was shortened from 187 to 132 ms and RV ejection fraction (RVEF) by right ventriculography increased from 35% to 42%.The distance between two ventricular leads (dRVI and aRVOT) was 93% with 85% of longitudinal and radial direction in the RV. The effective CRT in this case was characterized by covering RV in the longitudinal and radial direction. Conclusion: Separate two-point pacing on the dRVI and aRVOT, which assists the contraction in the longitudinal and radial dimension, is considered a potential position for CRT pacing and an effective method in ccTGA.