Extended Data Fig. 5: AERP.

(Upper) Stimulation protocol parameters, surface ECG lead II and intracardiac leads HRAp, RVd and RVp are displayed during atrial stimulation. At a critical S2S3 interval, no atrial response is elicited because the atrial tissue is still refractory. AERP is determined as the first (longest) S2S3 interval with loss of atrial depolarization. (Lower) Representative refractory curve and recovery curve of the atrial myocardium. The curves are determined by premature stimulation using the protocol described in the upper panel. Representative recordings and graphical analysis are obtained from a 4-month-old male mouse.