Poster Presentation & Flash Talk 46th Annual Meeting of the Fetal and Neonatal Physiological Society 2019

Fetal heart rate variability: a biomarker for evolving fetal hypoxic-ischaemic brain injury (#151)

Yoshiki Maeda 1 2 3 , Christopher A Lear 2 , Michi Kasai 2 4 , Victoria King 2 , Michael J Beacom 2 , Joanne O Davidson 2 , Tomoaki Ikeda 3 , Alistair J Gunn 2 , Laura Bennet 2
  1. Sakakibra Heart Institute, Fuchu, TOKYO, Japan
  2. Physiology, University of Auckland, Auckland, New Zealand
  3. Obstetrics and Gynecology, Mie University, Tsu, Mie, Japan
  4. Obstetrics and Gynecology, Yokohama Municipal University, Yokohama, Kanagawa, Japan

5d280c0eba71d-Figure+3+-+Frequency+domain.tifPurpose:Many cases of cerebral palsy after preterm birth are associated with hypoxia-ischaemia (HI) before birth. We assessed the utility of fetal heart rate (FHR) and FHR variability (FHRV) to predict evolving neural injury in utero.

Methods:Preterm fetal sheep (0.7 gestation) were surgically instrumented and underwent sham HI (n=8) or HI (25 min of umbilical cord occlusion) (n=8), with 21 days post-HI monitoring of FHR, FHRV and electroencephalographic (EEG) activity. Very low frequency (VLF), low frequency (LF) and high frequency (HF) FHRV power were calculated. Sample entropy (SampEn) was calculated as the complexity. The laboratory light phase was 06.00-18.00h. Sheep were fed ad libitum.

Results:HI was associated with transient suppression of VLF (0-8h), LF (0-3h) and HF (0-1h) power, followed by return to control and then a striking secondary reduction from ~18-72h. In contrast, SampEN was markedly increased from 0–48h post-HI (P<0.05), falling to control values in the last week, with increased nocturnal circadian activity and greater diurnal falls. Intriguingly, the circadian rhythms in VLF, LF and HF became markedly exaggerated after HI, with a significantly greater diurnal fall between 06.00-12.00h (P<0.05) > 7days post-HI. The magnitude of the circadian rhythm correlated with the severity of EEG suppression.

Conclusion:FHRV indices reflect evolving preterm neural injury. Their diurnal patterns may be particularly useful for assessing long-term recovery after HI.