Analysis of fetal ECG in fetal growth restriction

INTRODUCTION: Chronic intrauterine hypoxia influences fetal autonomous nervous system. Phase Rectified Signal Averaging (PRSA), a novel method of analysis of heart rate variability, is capable to calculate the average acceleration (AAC) and deceleration (ADC) capacity of the heart. PRSA depends on the parameter T which determines the periodicities that can be detected (i.e. the larger T the smaller the frequency of oscillations for which the method is most sensitive). The aim of the study was to explore AAC and ADC in intrauterine fetal growth restriction (IUGR) and controls. METHODS: Fetal ECG (fECG) was acquired by trans-abdominal ECG recording device (Monica AN24, UK) in 21 IUGR close to the time of delivery, and in 37 controls (defined as appropriate fetal growth and no maternal complications). All cases were recruited <34 weeks of gestation. AAC and ADC were calculated by PRSA, on inter-beats series automatically derived from fECG, adopting different T values (from T=1 to 50). Mann-Whitney test was used to test the differences. RESULTS: There were no differences in maternal demographic characteristics and gestational age at recruitment. Except for the analysis at T=1 and 2, AAC and ADC resulted significantly lower in IUGR for all other explored T values. The magnitude of the difference was higher at increasing values of T and was essentially given by the change in IUGR, while in the control group there were no significant differences in AAC and ADC at different T values (data not shown). The figure represents the ADC in IUGR and controls at T=1, 5, 25 and 50. CONCLUSIONS: Our results highlight the significant autonomic dysfunction in severe IUGR fetuses for a broad range of oscillations’periodicities (T>2). PRSA represents a novel promising tool for antepartum monitoring of fetal wellbeing.