Transmural activation dynamics of the sinus node in structural heart disease : mechanistic insights for arrhythmogenesis

and endocardial mapping of the sinus node region using two HD grid catheters (❋endocardial grid, ❋ epicardial grid) are shown along with an epicardial quadripolar pacing catheter (orange). SVC: superior vena cava, IVC: inferior vena cava, RAA: right atrial appendage, RA: right atrium, RV: right ventricle, AO: aorta. (C) Phase mapping showing increasing dispersion of signal phase between the epicardial and endocardial surfaces with sinus rhythm post overdrive pacing than at baseline. (D) Isochronal activation maps showing uniform wavefront propagation on endocardial and epicardial surfaces at baseline (black lines) but asymmetric propagation and conduction slowing on endocardial surface (white line) during sinus rhythm post overdrive pacing. TRANSMURAL ACTIVATION DYNAMICS OF THE SINUS NODE IN STRUCTURAL HEART DISEASE: MECHANISTIC INSIGHTS FOR ARRHYTHMOGENESIS