The majority of atrial arrhythmias in congenital heart disease are driven by a scar-related reentrant mechanism. As evidenced in this diagram, the scars and postsurgical fibrotic tissue provide boundaries as well as a substrate for slow conduction, which allows for propagation of electrical reentry and intraatrial reentrant tachycardia (IART). The arrows delineate potential routes for electrical reentry during the propagation of IART.
