AUTONOMIC CARDIOVASCULAR CONTROL IN NORMAL AND PREECLAMPTIC PREGNANCY

Background. Pre-eclampsia is regarded as a primary placental disorder, in which defect placentation causes endothelial and cardiovascular di sturbances. Evidence of disturbed neural cardiovascular control in thi s condition has been suggested, as well as in other hypertensive disea ses. The purpose of the present study was to non-invasively evaluate t he sympathovagal balance during normal and pre-eclamptic pregnancy. Me thods. In twelve healthy pregnant women, thirteen pre-eclamptic women and ten nonpregnant controls, heart rate, blood pressure and breathing movements were registered and recorded on a tape recorder for off-lin e analysis. Variability in heart rate, blood pressure and breathing mo vements were computed by an autoregressive spectral analysis algorithm . Heart rate variability was quantitated as the area under the spectra l curve, and Student's t-test was performed on logarithmic values. Res ults. Heart rate variability contained two major components in power, a low frequency peak predominantly attributed to sympathetic tone, and a high frequency peak reflecting vagal tone. Women with pre-eclampsia were characterized by a significantly reduced high frequency peak com pared to healthy pregnant (p = 0.03) and non-pregnant (p = 0.02) women . In the low frequency band there were no significant differences in p ower between the groups. Blood pressure variability did not differ bet ween the groups. Conclusions. The present results indicate that pre-ec lampsia is associated with decreased vagal control of the heart. Furth ermore, the results indicate that pregnancy pel se does not change sym patho-vagal balance.