History of Preeclampsia Adds to the Deleterious Effect of Chronic Stress on the Cardiac Ability to Flexibly Adapt to Challenge

Preeclampsia, a pregnancy-specific disorder, presents a major health problem during gestation, but is also associated with increased risk for cardiovascular complications in later life. We aimed to investigate whether chronic stress experience and preeclampsia may have additive adverse effects on the cardiac ability to flexibly adapt to challenge, that is, to mount an appropriately vigorous heart rate response to an acute psychological challenge, or whether they may perhaps have synergistic effects (e.g., mutual augmentation of effects). Blunted cardiac responding to challenge has been linked to poor health outcomes in the longer term. Women previously affected by preeclampsia and women after uncomplicated pregnancies were tested 15–17 weeks post-partum in a standardized stress-reactivity protocol, while cardiovascular variables were simultaneously recorded. Changes in heart rate and blood pressure in response to the stressor were analyzed with regard to the effects of history of preeclampsia and chronic stress experience. Findings indicated blunted cardiac responses in women with higher chronic stress experience (p = 0.020) and, independently from that, in women with a history of preeclampsia (p = 0.018), pointing to an additive nature of the effects of preeclampsia and chronic stress on impaired cardiovascular functioning. Consequently, if both are present, a history of preeclampsia may add to the already deleterious effects of the experience of chronic stress. The additive nature of the effects suggests that stress-reducing interventions, albeit they will not eliminate the heightened cardiovascular risk in patients with a history of preeclampsia, may improve their overall prognosis by avoiding further accumulation of risk

Phase synchronization of hemodynamic variables at rest and after deep breathing measured during the course of pregnancy.

BACKGROUND: The autonomic nervous system plays a central role in the functioning of systems critical for the homeostasis maintenance. However, its role in the cardiovascular adaptation to pregnancy-related demands is poorly understood. We explored the maternal cardiovascular systems throughout pregnancy to quantify pregnancy-related autonomic nervous system adaptations. METHODOLOGY: Continuous monitoring of heart rate (R-R interval; derived from the 3-lead electrocardiography), blood pressure, and thoracic impedance was carried out in thirty-six women at six time-points throughout pregnancy. In order to quantify in addition to the longitudinal effects on baseline levels throughout gestation the immediate adaptive heart rate and blood pressure changes at each time point, a simple reflex test, deep breathing, was applied. Consequently, heart rate variability and blood pressure variability in the low (LF) and high (HF) frequency range, respiration and baroreceptor sensitivity were analyzed in resting conditions and after deep breathing. The adjustment of the rhythms of the R-R interval, blood pressure and respiration partitioned for the sympathetic and the parasympathetic branch of the autonomic nervous system were quantified by the phase synchronization index γ, which has been adopted from the analysis of weakly coupled chaotic oscillators. RESULTS: Heart rate and LF/HF ratio increased throughout pregnancy and these effects were accompanied by a continuous loss of baroreceptor sensitivity. The increases in heart rate and LF/HF ratio levels were associated with an increasing decline in the ability to flexibly respond to additional demands (i.e., diminished adaptive responses to deep breathing). The phase synchronization index γ showed that the observed effects could be explained by a decreased coupling of respiration and the cardiovascular system (HF components of heart rate and blood pressure). CONCLUSIONS/SIGNIFICANCE: The findings suggest that during the course of pregnancy the individual systems become increasingly independent to meet the increasing demands placed on the maternal cardiovascular and respiratory system

Disturbed Cardiorespiratory Adaptation in Preeclampsia: Return to Normal Stress Regulation Shortly after Delivery?

Women with pregnancies complicated by preeclampsia appear to be at increased risk of metabolic and vascular diseases in later life. Previous research has also indicated disturbed cardiorespiratory adaptation during pregnancy. The aim of this study was to follow up on the physiological stress response in preeclampsia several weeks postpartum. A standardized laboratory test was used to illustrate potential deviations in the physiological stress responding to mildly stressful events of the kind and intensity in which they regularly occur in further everyday life after pregnancy. Fifteen to seventeen weeks postpartum, 35 women previously affected by preeclampsia (19 mild, 16 severe preeclampsia), 38 women after uncomplicated pregnancies, and 51 age-matched healthy controls were exposed to a self-relevant stressor in a standardized stress-reactivity protocol. Reactivity of blood pressure, heart rate, stroke index, and systemic vascular resistance index as well as baroreceptor sensitivity were analyzed. In addition, the mutual adjustment of blood pressure, heart rate, and respiration, partitioned for influences of the sympathetic and the parasympathetic branches of the autonomic nervous system, were quantified by determining their phase synchronization. Findings indicated moderately elevated blood pressure levels in the nonpathological range, reduced stroke volume, and elevated systemic vascular resistance in women previously affected by preeclampsia. Despite these moderate abnormalities, at the time of testing, women with previous preeclampsia did not differ from the other groups in their physiological response patterns to acute stress. Furthermore, no differences between early, preterm, and term preeclampsia or mild and severe preeclampsia were observed at the time of testing. The findings suggest that the overall cardiovascular responses to moderate stressors return to normal in women who experience a pregnancy with preeclampsia a few weeks after delivery, while the operating point of the arterial baroreflex is readjusted to a higher pressure. Yet, their regulation mechanisms may remain different

Maternal cardiovascular and endothelial function from first trimester to postpartum

<div><p>Objective</p><p>To explore noninvasively the complex interactions of the maternal hemodynamic system throughout pregnancy and the resulting after-effect six weeks postpartum.</p><p>Methods</p><p>Eighteen women were tested beginning at the 12^th week of gestation at six time-points throughout pregnancy and six weeks postpartum. Heart rate, heart rate variability, blood pressure, pulse transit time (PTT), respiration, and baroreceptor sensitivity were analyzed in resting conditions. Additionally, hemoglobin, asymmetric and symmetric dimethylarginine and Endothelin (ET-1) were obtained.</p><p>Results</p><p>Heart rate and sympathovagal balance favoring sympathetic drive increased, the vagal tone and the baroreflex sensitivity decreased during pregnancy. Relative sympathetic drive (sympathovagal balance) reached a maximum at 6 weeks postpartum whereas the other variables did not differ compared to first trimester levels. Postpartum diastolic blood pressure was higher compared to first and second trimester. Pulse transit time and endothelial markers showed no difference throughout gestation. However, opposing variables PTT and asymmetric dimethylarginine (ADMA) were both higher six weeks postpartum.</p><p>Conclusions</p><p>The sympathetic up regulation throughout pregnancy goes hand in hand with a decreased baroreflex sensitivity. In the postpartum period, the autonomic nervous system, biochemical endothelial reactions and PTT show significant and opposing changes compared to pregnancy findings, indicating the complex aftermath of the increase of blood volume, the changes in perfusion strategies and blood pressure regulation that occur in pregnancy.</p></div

Steps to compute the phase synchronization: First, the signals, here systolic blood pressure (SBP) and R-R interval (RRI), were band-pass filtered.

<p>The black line denotes the filter characteristic of the band pass filter for the LF-component, the grey line denotes the filter characteristic of the band pass filter for the HF-component. The Hilbert transformation was employed to calculate the phase of the filtered signals. The rectangles with the symbol φ_ti denote the Hilbert transformation and the resulting phase at the time t_i. In the final step the phase difference Ψ_ti was used to quantify the phase synchronization γ for the related period.</p

Phase synchronization indices of the <i>LF-components</i> (mean ± SD) of participants and statistical results.

<p>LF = low frequency; γ = synchronization index; RRI = R-R interval; SBP = systolic blood pressure; DBP = diastolic blood pressure; DB = deep breathing. Note : Multivariate analyses of variance significant for main effect “week” only.</p

Heart rate and heart rate variability variables (mean ± SD) of participants and statistical results.

<p>HR = heart rate; SDNN = standard deviation of normal-to-normal beat; rMSSD = root mean squared successive differences of R-R intervals; LF = low frequency (0.04–0.15 Hz); HF = low frequency (0.15–0.40 Hz); ln = natural logarithmic transformation; DB = deep breathing. <b>*</b>denotes a significant difference (<i>p<.05) between rest and post DB</i> in case of a significant univariate interaction effect.</p

LF/HF ratio (ln(LF/HR)_RRI; mean ± SD) throughout gestation: Black bars depict the values of the variables in rest, the grey bars show the post stress (deep breathing) condition (RRI = R-R interval; LF = low frequency; HF = high frequency; ln = natural logarithmic transformation).

<p>*denotes a significant difference (<i>p<.05) between rest and post DB</i> in case of a significant univariate interaction effect.</p

Phase synchronization indices of the <i>HF-components</i> (mean ± SD) of participants and statistical results.

<p>LF = low frequency; γ = synchronization index; RRI = R-R interval; SBP = systolic blood pressure; DBP = diastolic blood pressure; RESP = respiration; DB = deep breathing. <b>*</b>denotes a significant difference (<i>p<.05) between rest and post DB</i> in case of significant a univariate interaction effect. Note : Multivariate analyses of variance of γ<i>_SBPxRRI,HF</i>, γ<i>_DBPxRRI,HF</i> and γ<i>_SBPxDBP,HF</i> significant for main effects only.</p