BACKGROUND

Neonates with critical congenital heart disease (cCHD) undergo a complicated transition to ex-utero life. However, continuous monitoring of autonomic tone using heart rate variability is currently lacking.

MATERIALS AND METHODS

We retrieved continuous electrocardiograms from the time of admission or from 10 days prior to surgery for neonates with dextro-transposition of the great arteries (d-TGA) and hypoplastic left heart syndrome (HLHS). Beat-to-beat intervals (RRi) were calculated and divided into 10-min epochs. Spectral metrics, including low-frequency (LF) and high-frequency (HF) powers, as well as detrended fluctuation analysis metrics (α, α, RMS, and RMS), were computed for RRi within each epoch and averaged over 24 h. The relationship between RRi metrics and time to surgery was analyzed using linear mixed-effects models, adjusting for prenatal and postnatal factors.

RESULTS

The study included 10 neonates with HLHS and 23 with d-TGA. RRi metrics were available for 110 days. In the unadjusted models, LF power (Estimate: -4.4×10, P = 0.02), HF power (-4.1 x 10, 5 x 10), RMS(-3.7 x 10, 8.7 x 10), and RMS(-1.4× 10, 0.02) were all negatively associated with time to surgery, with HF power showing the strongest association. After adjusting for covariates, HF power retained its significant negative association with time (-0.04, P = 0.03). The cCHD diagnosis did not significantly influence RRi metrics.

CONCLUSIONS

In neonates with cCHD, there is a progressive decline in autonomic function leading up to surgery. RRi metrics may serve as valuable indicators of deteriorating physiology in these patients.