Pearls for ablation in congenital heart disease.

Tachyarrhythmias occur in patients having congenital heart disease most commonly related to surgically created or naturally occurring conduction obstacles, and to postoperative hemodynamic effects on cardiac muscle. Less frequently, the underlying disease is associated with tachycardia substrates. Thorough knowledge of the patient's congenital anatomy and surgical procedures is required before considering catheter ablation. In many instances, procedural considerations should include meticulous hemodynamic surveillance, analogous to patients having structurally normal heart but cardiomyopathy. This includes careful selection of sedating and anesthetic agents. Congenital heart defects that have a higher than expected incidence of naturally occurring tachyarrhythmia substrates include Ebstein anomaly of the tricuspid valve, congenitally corrected transposition, and some of the heterotaxies. Intraatrial reentry tachycardia and atrial flutter are especially prevalent following the Mustard or Senning operations for d-transposition of the great arteries and the earlier Fontan type operations. Although these tachyarrhythmias are not as frequent following atrial septal defect repair, the high incidence of this defect also makes these patients germaine to this discussion. Focal atrial tachyacrdia and atrioventricular nodal reentry tachycardia also occur in these patient groups. Macroreentry ventricular tachycardia occurs most frequently following right ventricular outflow tract surgery, especially following repair of tetralogy of Fallot. This article focuses on the technical aspects of catheter ablation of these arrhythmias, due to the challenges presented by the underlying anatomy compared with patients having normal hearts.