Mechanisms of atrial reentry tachycardia after surgery for congenital heart disease

Abstract

The concept of reentry was first postulated in the late 19th century. Decades of work culminated in the revelation that transient entrainment could establish reentry as the mechanism for a number of tachyarrhythmias. The first atrial arrhythmia so defined was type I atrial flutter (or isthmus dependent artial flutter). Pace mapping using entrainment revealed atrial flutter as a macroreentrant right atrial arrhythmia moving in a counterclockwise fashion dependent on anisotropic barriers (crista terminalis–eustachian valve ridge and tricuspid annulus) for its maintenance. As a consequence of the surgical repair of congenital heart disease, other fixed barriers to conduction are created such as atriotomy scars and suture lines around septal defect patches and intra-atrial baffles. Concomitant changes in the size and thickness of the right atrium along with hemodynamic perturbations may contribute to arrhymogenicity. These factors have resulted in a significant post-operative incidence of isthmus dependent atrial flutter and intra-atrial reentrant tachycardia (IART). Because of the poor response to drug therapy, attention has shifted to radiofrequency ablation as a means of management. Immediate results have been gratifying. However, the recurrence risk is high indicating the need for better methods for delivering ablative and non-ablative therapies.