MULTIFRACTAL ANALYSIS OF HEART RATE VARIABILITY IN NORMAL AND GROWTH-RESTRICTED FETUSES

Abstract

Multifractal analysis has recently been validaded as an excellent method by which to analyze heart rate variability and in distinguishing healthy subjects from patients with various types of the cardiac nervous system dysfunction. Our objective was to improve the understanding of the multifractal properties of fetal heart rate (FHR) variability in healthy normal fetuses according to gestational age, and to determine whether the heart rate dynamics in growth-restricted fetuses is different from normal fetuses by multifractal analysis. One hundred nineteen FHR recordings obtained from healthy normal fetuses and 68 recordings obtained from small-for-gestational-age (SGA) fetuses were analyzed to examine gestational and pathologic changes of the degree of multifractality. A significant decrease was observed in the degree of multifractality of healthy normal fetuses according to gestational age. The degree of multifractality of SGA fetuses was significantly higher than that of healthy normal fetuses. Moreover, the degree of multifractality of complicated SGA fetuses who ultimately showed nonreassuring FHR patterns was significantly higher than that of uncomplicated SGA fetuses. And the latter was significantly higher than that of healthy normal fetuses. The degree of multifractality appears to be a sensitive probe for detecting subtle, and possibly important, changes that occur in fetuses with intrauterine growth restriction (IUGR), and may be helpful in the early and non-invasive detection of placental insufficiency or incipient IUGR. The mechanisms underlying FHR regulation in IUGR fetuses seem to be different from those of cardiac pathology in adults.