Preoperative Heart Rate Variability and Parasympathetic Modulation in Newborns with Transposition of the Great Arteries Undergoing Arterial Switch Operation

Introduction: We retrospectively assessed preoperative cardiac autonomic regulation in neonates with TGA who subsequently underwent arterial switch operation. Materials and Methods: Neonates treated between 1 January and 31 December 2024 were studied. Heart rate variability was derived from continuous ECG recordings, with low-frequency and high-frequency spectral components calculated from RR intervals. Longitudinal associations between HRV indices and the interval to surgery were evaluated using linear mixed-effects models with adjustment for relevant clinical covariates. Results: Twenty neonates were included. The median age at ASO was 7 days (IQR 5–9), median weight was 3100 g (IQR 2900–3400), and median preoperative oxygen saturation was 76% (IQR 70–82%). Balloon atrial septostomy had been performed in 10 patients. HRV data represented 150 patient-days of monitoring. In unadjusted analyses, both LF and HF power declined as surgery was delayed, with the strongest association observed for HF power. In the adjusted mixed-effects model, longer time to surgery remained independently associated with lower HF power (β = −0.07, 95% CI −0.129 to −0.011, p = 0.03). Conclusions: Serial HF measurements may reflect progressive changes in autonomic regulation during the preoperative period in neonates with TGA.