Serial assessment of variability in heart rate in children with the Fontan circulation

Area of Science:

• Cardiology
• Pediatric Cardiology
• Autonomic Neuroscience

Background:

• Autonomic nervous system (ANS) function is crucial for cardiovascular regulation.
• Reduced heart rate variability (HRV) is observed in patients with Fontan circulation.
• Longitudinal changes in HRV in pediatric Fontan patients are not well-documented.

Purpose of the Study:

• To investigate longitudinal changes in heart rate variability (HRV) in children with Fontan circulation.
• To assess the development of autonomic nervous system (ANS) imbalance over time post-Fontan procedure.
• To determine if routine ambulatory electrocardiogram (ECG) monitoring can detect these changes.

Main Methods:

• Studied 13 pediatric patients post-total cavopulmonary connection (Fontan procedure) and 37 age/gender-matched healthy controls.
• Performed complete echocardiography and 24-hour ambulatory ECG for HRV analysis.
• Conducted three follow-up examinations at mean intervals of 4.4, 5.6, and 7.2 years post-procedure.

Main Results:

• Patients with Fontan circulation exhibited reduced HRV compared to controls.
• Significant differences in high-frequency power (p=0.05, p=0.03) were observed at second and third follow-ups.
• The low-to-high-frequency ratio progressively increased, indicating sympatovagal imbalance (p=0.03 at third examination).

Conclusions:

• Ambulatory ECG monitoring with HRV analysis is effective in detecting progressive autonomic dysfunction in Fontan patients.
• Fontan circulation is associated with a developing sympatovagal imbalance over time.
• Findings highlight the importance of long-term cardiovascular monitoring in pediatric Fontan survivors.