Heart Rate Variability in Intrauterine Growth Retarded Infants and Normal Infants with Smoking and Non-smoking Parents, Using Time and Frequency Domain Methods

摘要

Intrauterine growth retardation (IUGR) and low birth weight have been linked with an increased risk of cardiovascular disease, hypertension and stroke in later life. Studies have shown cardiovascular mortality is associated with altered autonomic nervous system activity, which can be assessed using measurements of how the heart rate is changing over time, known as heart rate variability (HRV). A reduced HRV indicates a reduction in the autonomic activity. Heart rate data of 24 children, at age 9-10 years, was analysed, to investigate the HRV of IUGR and normal birth weight children in relation to their parents' smoking habits. In the time domain Poincare plots were produced, and in the frequency domain periodograms created using the FFT and the Lomb method. The Lomb method can cope with non-uniformly sampled data series without the need for interpolation and re-sampling. Measurements of the low to high frequency ratios showed no difference between the groups of children in the study, however measurements of the energy of peaks in the high frequency region due to respiratory sinus arrhythmia showed a reduction in high frequency strength for IUGR children with smoking parents, when compared to IUGR children with nonsmoking parents.