Changes in Heart Rate and Heart Rate Variability During Surgical Stages to Completed Fontan Circulation

Area of Science:

• Pediatric Cardiology
• Autonomic Nervous System Function
• Cardiac Surgery Outcomes

Background:

• Arrhythmia is linked to heart rate variability (HRV), reflecting autonomic nervous system control of the heart.
• The bidirectional Glenn procedure (BDG) may impact autonomic nervous ganglia, potentially reducing HRV.
• Understanding these effects is crucial for managing children with univentricular heart defects.

Purpose of the Study:

• To investigate changes in heart rate and HRV in children with univentricular heart defects undergoing stepwise surgical palliation.
• To compare HRV and heart rate in patients before and after BDG and total cavopulmonary connection (TCPC) with healthy controls.
• To determine the impact of surgical procedures on cardiac autonomic regulation.

Main Methods:

• Collected 24-hour Holter-ECG recordings from pediatric patients (n=47 before BDG, n=47 after BDG, n=45 after TCPC) and healthy controls (n=38).
• Analyzed heart rate variability (HRV) using spectral and Poincaré methods.
• Compared age-related z scores using linear mixed effects modeling.

Main Results:

• Total HRV was significantly lower in patients pre-BDG compared to controls.
• Mean heart rate decreased significantly after BDG compared to before.
• Patients after BDG and TCPC exhibited reduced heart rate and HRV compared to controls, with further HRV reduction post-TCPC.

Conclusions:

• Autonomic regulation of cardiac rhythm is significantly affected by both BDG and TCPC procedures.
• Reduced heart rate and HRV post-surgery may contribute to postoperative arrhythmic events in these patients.
• Stepwise surgical palliation impacts cardiac autonomic function in children with univentricular heart defects.