Background:
Pediatric care for children with congenital heart disease (CHD) has continuously improved over the past few decades. As a result, clinicians are increasingly confronted with medical conditions that arise from the natural progression of the disease. More than half of adults with CHD experience atrial arrhythmias during their lifetime, with atrial fibrillation (AFib) emerging as the dominant form after the age of 50. Double Inlet Left Ventricle (DILV) is an extremely rare heart defect, accounting for approximately 1% of all CHD. Catheter ablation of AFib in this set of patients can pose challanges because of their complex cardiac anatomy and unique procedural considerations.
Clinical Case:
We report a rare case of a 50-year-old woman with DILV and pulmonary valve stenosis, allowing her to remain unoperated into adulthood. In 2018, she underwent a cryoballoon ablation and now presented with highly symptomatic recurrences of AFib for redo procedure.
The patient's cardiac anatomy was consistent with a classic DILV featuring a functional single ventricle and ventriculo-arterial discordance. Additional findings included a large atrial septal defect (ASD) with a functional common atrium and a common right pulmonary vein (RCPV). Pre-procedural evaluation comprised an MRI and right-heart catheterization.
Electroanatomic mapping was performed with the EnSite™ NavX™. A significant medial shift of the left atrial sagittal axis was observed, along with a leftward and caudal displacement of the left atrial appendage. In nearly most of the left atrium, endocardial bipolar voltage was <1.5 mV, with only scattered low-voltage areas (LVA) <0.5 mV. The lateral pulmonary veins demonstrated preserved antral conduction, likely reflecting a previously deep balloon position. On the septal aspect, conduction into the RCPV was fully preserved.
Ablation was guided by the Lesion Size Index (LSI) using a TactiFlex™ catheter, with a target LSI of 5.5 along the anterior wall and 5.0 along the posterior wall, resulting in first-pass isolation of all pulmonary veins. Due to the large ASD, maintaining a stable catheter position along the septal line was challenging, allowing for only a ~5-safety margin to the pulmonary veins inferiorly.
Conclusion:
A catheter ablation of AFib can be performed safely and effectively in patients with DILV, although it can prove technically demanding due to the complex and unusual atrial anatomy—such as when maintaining a safe distance on the septal side in the presence of a large ASD or common atrium. Children with uncorrected DILV rarely reach their adulthood. However, due to improved survival and a high prevalence of atrial arrhythmias a growing number of patients with CHD are expected to require catheter ablation in the future. A thorough understanding of the underlying morphology and careful procedural planning are essential for a successful outcome.
