Fig 2. The computer activation model of the human SAN complex was validated using the optical mapping of the same human heart under both baseline and adenosine (Ado).

A, The activation maps of the human SAN-RA in the computer model where the earliest pacemaker originated from the SAN center and propagated into the RA via the middle lateral SACP under baseline conditions. The introduction of Ado shifted the leading pacemaker to the SAN tail and changed the exit site to the superior lateral SACP as in ex-vivo optical mapping experiments. B, Optical mapping of the same human heart ex-vivo had qualitatively similar leading pacemaker sites and propagation patterns [1]. SAN–sino-atrial node, RA–right atrium, SACP–SAN conduction pathway, SACTsr–SAN conduction time during sinus rhythm, Ado–Adenosine, CT–crista terminals, IAS–interatrial septum, SVC–superior vena cava.