Detailed delineation and electrophysiological assessments of an atriofascicular pathway masking antegrade right bundle branch block

Figures

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  Figure 1. A: Twelve-lead electrocardiogram (ECG) during sinus rhythm showed ventricular preexcitation with a left bundle branch block (LBBB) pattern. B: Twelve-lead ECG during tachycardia showed wide-QRS tachycardia with LBBB pattern. C: Atrial extrastimulation from the high right atrium revealed progressive preexcitation with LBBB pattern. D: Twelve-lead ECG and intracardiac recordings at tachycardia initiation by atrial extrastimulation. The earliest atrial potential was in the His bundle region, and the His potential (H) could not be identified during the tachycardia. A = atrial electrogram, CS = coronary sinus, d = distal, p = proximal, RV = right ventricle, V = ventricular electrogram.

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  Figure 2. A: Delineation of the Mahaim potentials and the Purkinje-like potentials following the Mahaim potentials. Green tags indicate Mahaim potentials and the Purkinje-like potentials following the Mahaim potentials recorded during pacing from the right atrial appendage. The interval from atrial pacing to the Mahaim or Purkinje-like potential at each green tag is shown. At site 5, the Purkinje-like potential was observed immediately before the ventricular electrocardiogram. Yellow and pink tags indicate His and right bundle branch (RBB) potentials recorded during sinus rhythm, respectively. B: The course of the Mahaim potentials (white line), the Purkinje-like potentials following the Mahaim potentials (white dotted lines), and the breakthrough site to the ventricular myocardium (white star). C: The position of the Advisor HD Grid (Abbott, St. Paul, MN) catheter and intracardiac recordings at the time of occurrence of RBB block (RBBB). D: Schematic drawing of the estimated anatomic course of the atriofascicular pathway and its relationship with the RBB. CS = coronary sinus; HRA = high right atrium; LAO = left anterior oblique view; LV = left ventricle; RAO = right anterior oblique view;…

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  Figure 3. A: Twelve-lead electrocardiogram (ECG) and intracardiac recordings at entrainment pacing from the electrodes of the Advisor HD Grid catheter (Abbott, St. Paul, MN) where the Mahaim potential was recorded. The post-pacing interval of the Mahaim potential was identical to the tachycardia cycle length, and the QRS morphology indicated concealed entrainment. The interval between the pacing spike to the local ventricular potentials was identical to that between the Mahaim potential to the local ventricular potentials during tachycardia. B: Intracardiac recordings and 3-dimensional image at the successful radiofrequency (RF) application site (red tag). Although the Mahaim potential was recorded at this site with HD grid catheter, it could not be identified with the ablation catheter. C: Twelve-lead ECG during the RF application. The RF application was performed during pacing from the right atrial appendage. Preexcitation disappeared and right bundle branch block (RBBB) was manifested simultaneously 6 seconds after the start of RF application. AF = atriofascicular. Other abbreviations are as in Figures 1 and 2.