An Incessant Atrial Tachycardia Originating from Epicardial Left Atrial Appendage in a 12-Year-Old Girl: Ablation or Excision?
Atrial tachycardia (AT) originating from the left atrial appendage (LAA) is a rare but clinically significant arrhythmia, particularly in pediatric patients. The LAA, a remnant of the embryonic left atrium, is a complex structure with thin walls and a trabeculated interior, making it a challenging site for catheter ablation (CA). This case report details the successful management of incessant AT in a 12-year-old girl through a combination of epicardial CA and surgical left atrial appendectomy (SAE), highlighting the technical challenges, clinical outcomes, and long-term follow-up.
Clinical Presentation and Initial Evaluation
The patient, a 12-year-old girl weighing 46 kg and standing 165 cm tall (body surface area of 1.45 m²), presented with a 5-month history of drug-refractory palpitations. Her electrocardiogram (ECG) revealed persistent AT with variable conduction (3:1 to 1:1) and a maximum heart rate of 150 beats per minute. The echocardiogram showed an enlarged left atrial diameter (LAD) of 37 mm (normal range <35 mm) and normal left ventricular dimensions (left ventricular end-diastolic diameter [LVEDD] of 48 mm and left ventricular end-systolic diameter [LVESD] of 30 mm) with a preserved left ventricular ejection fraction (LVEF) of 67%. Laboratory tests indicated elevated levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP, 2586 pg/mL; normal range <285 pg/mL), alanine aminotransferase (ALT, 109 U/L; normal range <75 U/L), and aspartate aminotransferase (AST, 43 U/L; normal range <38 U/L), suggesting secondary cardiac strain. The P-wave morphology on ECG, characterized by negativity in leads I and aVL and positivity in the inferior leads and lead V1, localized the arrhythmia to the left atrium.
Electrophysiological Study and Endocardial Ablation Attempt
After ruling out reversible causes and confirming the absence of left atrial thrombus via transesophageal echocardiography, the patient underwent an electrophysiological study. Standard catheters were positioned in the coronary sinus, His bundle region, and high anterolateral right atrial wall. A transseptal puncture was performed using the modified Brockenbrough technique, and systemic anticoagulation was achieved with intravenous heparin. Activation mapping with the Ensite Precision cardiac mapping system revealed a distal-to-proximal atrial activation sequence in the coronary sinus. Endocardial mapping identified early activation sites in the right ventricular outflow tract (112 ms) and LAA (105 ms) relative to the onset of the A wave at CS9-10.
Radiofrequency ablation was attempted at multiple sites in the LAA ostium using a TactiCath Quartz ablation catheter (temperature of 43°C, power settings of 17–25 W). Despite these efforts, the tachycardia persisted, prompting consideration of an alternative approach.
Epicardial Ablation and Surgical Appendectomy
Given the failure of endocardial ablation and the risk of complications such as LAA perforation, the patient was referred for epicardial ablation. Under general anesthesia with selective single-lung ventilation, the left pericardium was accessed through the fourth intercostal space. Activation mapping on the epicardial surface of the LAA identified the earliest activation site (120 ms ahead of CS9-10) at the apex of the upper lobe. Angiography confirmed this site’s proximity to the endocardial site of earliest activation.
Radiofrequency ablation was performed using a FlexAbility irrigated ablation catheter (temperature of 43°C, irrigation rate of 30 mL/min, power settings of 30 W). The tachycardia was terminated within 5 seconds of energy application, and no further arrhythmias could be induced. Following ablation, the LAA was excised, and macroscopic examination revealed ablation lesions on the epicardial surface. The surgical procedure lasted 90 minutes without complications.
Post-Procedure Outcomes and Follow-Up
Seven days post-procedure, echocardiography showed a reduction in LAD to 29 mm, LVEDD to 48 mm, and LVESD to 32 mm, with an LVEF of 61%. Laboratory markers normalized (NT-proBNP: 133 pg/mL, ALT: 47 U/L, AST: 28 U/L). Over a 12-month follow-up period, the patient remained free of symptomatic arrhythmias, demonstrating the efficacy of the combined approach.
Discussion
The LAA’s complex anatomy and thin walls make it a challenging site for catheter ablation. Endocardial ablation, while often effective, carries a risk of perforation and incomplete lesion formation due to the trabeculated structure. Epicardial ablation offers an alternative but is limited by the pericardial space and the thermal homeostatic effect of cavitary saline infusion. In this case, the combination of epicardial ablation and surgical appendectomy provided a definitive solution, eliminating the arrhythmia and reducing the risk of recurrence.
The mechanisms underlying AT originating from the LAA remain unclear, but abnormal automaticity and anisotropic junctional tissue are thought to play a role. The success of this approach underscores the importance of individualized treatment strategies, particularly in pediatric patients with complex arrhythmias.
Conclusion
This case illustrates the challenges and successful management of incessant AT originating from the epicardial LAA in a pediatric patient. The combination of epicardial catheter ablation and surgical appendectomy provided a definitive solution, with excellent short- and long-term outcomes. Further studies are needed to evaluate the safety and efficacy of this approach in a larger cohort of pediatric patients.
doi.org/10.1097/CM9.0000000000001778
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