Blood Pressure Variability as a Marker of Sympathetic Hyperreactivity in Postpartum Patients with Preeclampsia, with and without Chronic Hypertension
Michael Kirschner1, Helen Woolcock Martinez2, Leonidas Taliadouros3, Noora Haghighi1, Pedro Castro4, Whitney Booker2, Natalie Bello5, Nils Petersen6, Eliza Miller1
1Department of Neurology, 2Department of Obstetrics & Gynecology, Columbia University Irving Medical Center, 3Department of Civil Engineering and Engineering Mechanics, Columbia University, 4Department of Neurology, University of Porto, 5Department of Cardiology, Cedars-Sinai Medical Center, 6Department of Neurology, Yale University
Objective:
Compare blood pressure variability (BPV) between postpartum patients with preeclampsia (PE) and patients with preeclampsia superimposed on chronic hypertension (siPE).
Background:
Preeclampsia, a multi-organ system hypertensive syndrome complicating pregnancy, is associated with sympathetic hyperreactivity. BPV reflects a component of sympathetic noradrenergic activity and, when coupled with impaired cerebral autoregulation, increases susceptibility to cerebral hypo- or hyper-perfusion. siPE is associated with a higher stroke risk than PE. Data are limited regarding autonomic function in PE during the postpartum period, when stroke risk is highest. We hypothesized that postpartum patients with siPE have higher BPV compared to those with PE.
Design/Methods:
We recruited postpartum patients with PE and siPE and continuously measured mean arterial blood pressure (MAP) using finger plethysmography for up to 24 hours. We converted MAP data to the frequency domain using a Fourier Transform. Low frequency (LF, 0.04-0.15 Hz) signals, associated with sympathetic noradrenergic activity, were isolated and transformed to a normal distribution using a power ladder. We averaged frequency-domain BPV every hour and over the entire monitoring period for each patient using spectral analysis. We compared average and hourly BPV using repeated measures ANOVA between those with PE and siPE.
Results:
We analyzed data from 23 patients (total 295.8 hours). Median monitoring time was 11.7 hours (IQR 5.2 – 19.5). Nine (39%) patients had siPE. Total LF BPV was non-significantly lower in those with siPE compared to PE (4.62 mmHg2 vs. 7.31 mmHg2, P = 0.098), as was hourly LF BPV (P = 0.139).
Conclusions:
Contrary to our hypothesis, patients with siPE did not have higher LF BPV than those with PE, suggesting similar sympathetic activity and autonomic function in the postpartum period. Further studies with larger sample sizes should correlate sympathetic activity and autonomic function to clinical risk and mechanism of neurovascular injury in PE and siPE.
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