15 - Atrial tachyarrhythmias in adults with congenital heart disease

Abstract

Cardiac arrhythmias are a common problem in patients with congenital heart disease (CHD), particularly after they have undergone reparative or palliative surgical procedures. Atrial tachyarrhythmias are the most prevalent, with a lifetime risk of approximately 50%, regardless of the severity of the congenital defects. Macroreentry localized to the right atrium (RA) is the most common mechanism, followed by atrial fibrillation. Focal atrial tachycardias (ATs) are also observed, but less frequently. For macroreentrant ATs in adults with repaired CHD, three RA circuits are generally identified: (1) lateral wall circuits with reentry around or related to the lateral atriotomy scar; (2) septal circuits with reentry around an atrial septal patch; and (3) typical atrial flutter circuits using the cavotricuspid isthmus (CTI). Typical atrial flutter is the most common single mechanism and usually coexists with other forms. Atrial macro- reentry in the RA free wall is the most common form of non–CTI-dependent RA macroreentry. Left atrial macroreentrant circuits are infrequent in this patient population. The complexity of the macroreentrant AT circuits depends on the underlying congenital anomaly and the complexity of the surgical repair. Very complex or multiple reentry circuits can be seen after placement of an intraatrial baffle (Mustard or Senning correction for transposition of the great vessels) in an extremely dilated RA, after a Fontan procedure, and in patients with a univentricular heart.