HEART-RATE AND BLOOD-PRESSURE VARIABILITIES ARE INCREASED IN PREGNANCY-INDUCED HYPERTENSION

OBJECTIVE: Our purpose was to study whether cardiovascular changes in pregnancy-induced hypertension are associated with the increase in sym pathetic control of hemodynamics and change in sympathovagal balance. STUDY DESIGN: Fourteen women with pregnancy-induced hypertension and 1 6 women with uncomplicated pregnancies of similar duration were studie d. Electrocardiographic signals and arterial blood pressure (Finapres monitor, Ohmeda) were continuously measured noninvasively throughout t he study. Heart rate and blood pressure were measured while the subjec t was breathing (1) with her normal tidal volume at a frequency of 15 breaths per minute and (2) as deeply as possible at a frequency of six breaths per minute. Heart rate and systolic blood pressure variabilit y were calculated with use of the autoregressive model of spectral ana lysis. RESULTS: Heart rate and systolic blood pressure variabilities w ere significantly increased in women with pregnancy-induced hypertensi on compared with normotensive pregnant women. This increase was greate st in the high frequency component of heart rate variability (p = 0.02 ) while the women were breathing with a normal tidal volume. Further, the medium frequency (p = 0.03) and high-frequency variabilities (p = 0.03) of systolic blood pressure were significantly increased in women with preeclampsia compared with normotensive pregnant subjects, CONCL USIONS: Neural control of the heart rate and blood pressure are distur bed in pregnancy-induced hypertension, as shown by increased heart rat e and blood pressure variability. Both the sympathetic and parasympath etic control of the heart rate and blood pressure appear to be increas ed. The maladaptation of the cardiovascular system in women with pregn ancy-induced hypertension is manifested as a lack of the physiologic d ecline in cardiovascular oscillations.