Mechanism and outcomes of catheter ablation for ventricular tachycardia in adults with repaired congenital heart disease

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

“…Most spontaneous and induced monomorphic VTs in patients with CHD referred for ablation are due to macroreentry, with a critical isthmus defined by anatomical barriers, bordered by unexcitable tissue ( S9.11.3.1 – S9.11.3.4 , S9.11.3.6 , S9.11.3.7 ); however, focal mechanisms are occasionally encountered ( S9.11.3.3 , S9.11.3.4 , S9.11.3.6 ). The boundaries of AIs are the valve annuli and (unlike most other acquired heart diseases) patch material and surgical incisions.…”

“…Four VT-related AIs in tetralogy of Fallot have been identified: isthmus 1, bordered by the tricuspid annulus and the scar or patch in the anterior RVOT; isthmus 2, between the pulmonary annulus and the RV free wall incision or RVOT patch, sparing the pulmonary valve annulus; isthmus 3, between the pulmonary annulus and the VSD patch or septal scar; and isthmus 4 (which is rarely encountered), between the VSD patch or septal scar and the tricuspid annulus in case of an inferior muscular rim ( S9.11.3.2 ) ( Figure 12 ). Additional AIs bordered by surgical scars and valve annuli have been described after surgery for other CHDs, including complex D-TGA, VSD closure, and surgery for Ebstein’s anomaly ( S9.11.3.4 , S9.11.3.6 , S9.11.3.15 ). Substrate formation might depend on the coincidence of pathological myocardial remodeling and anatomical boundaries determined by the type and timing of prior corrective surgery.…”

Point catheter ablation of macro-re-entrant ventricular tachycardia in a patient after surgical repair for double-outlet right ventricle

“…A previous report recommended linear ablation for re-entrant ventricular tachycardia in patients after surgical repair for CHD; 1 moreover, the strategy to confirm conduction block across the anatomical isthmus has recently been underscored for ablation of ventricular tachycardia in patients with repaired CHD 2 . In contrast, this is the first case report to demonstrate the effective use of intra-cardiac ultrasound technique for successful point ablation of re-entrant ventricular tachycardia in a patient with a ventricular septal defect patch.…”

Ventricular arrhythmias and sudden cardiac death in adults with congenital heart disease

“…Identification of a select group of low-risk patients in whom catheter ablation may be performed without ICD implantation remains a challenge. For example, the incidence of recurrent ventricular tachycardia or sudden death appears to be low in the subset of adults with CHD who have preserved ventricular function, macroreentrant ventricular tachycardia and successful catheter ablation with demonstrated bidirectional conduction block across the transected isthmus 14 15. Recommendations for ablation are summarised in table 1.…”