OP 45 Maternal functional hemodynamics and natriuretic peptides at 22–24 weeks of gestation

Abstract

Introduction We have previously shown that pregnant women have a limited preload reserve perhaps due to volume overload (1,2). Cardiac overload may result in increased production of natriuretic peptides by the heart. Objective Our primary objective was to investigate the association between functional hemodynamics and natriuretic peptides in pregnant women at 22–24 weeks of gestation. A secondary aim was to explore differences in maternal hemodynamics and natriuretic peptide levels between women who later develop preeclampsia and those who do not. Materials and methods This was a prospective cross-sectional study of 347 pregnant women. Maternal cardiac function and systemic hemodynamics was investigated at baseline and after 90s of passive leg raising (PLR) using impedance cardiography (ICG). Uterine artery pulsatility index (UtA PI) was measured using Doppler ultrasonography. Fasting venous blood samples were obtained for the analysis of natriuretic peptides (proANP and NT-proBNP). Results proANP correlated significantly with maternal cardiac output ( r = −0.118; p = 0.028) and cardiac index ( r = −0.107; p = 0.047) but not with NT-ProBNP. Preload reserve defined as percent change in stroke volume or cardiac output from baseline to PLR did not correlate with natriuretic peptide levels. However, NT-ProBNP correlated significantly with percent change in diastolic ( r = −0.157; p = 0.003) and mean arterial blood pressure (MAP) caused by PLR ( r = −0.151; p = 0.005). At 22–24 weeks, 21 (6.0%) women who later developed preeclampsia had higher mean UtA PI (1.22 vs. 0.85; p = 0.018), MAP (88 vs. 79 mmHg; p = 0.018) and systemic vascular resistance index 2296 vs. 1770 dyne s m 2 /cm 5 ; p = 0.010) compared to those who did not, but had similar natriuretic peptide levels. Conclusion Cardiac output correlated with proANP but not with NT-proBNP at 22–24 weeks of gestation. These natriuretic peptides did not reflect preload reserve and did not predict the development of preeclampsia later in pregnancy. Further studies are needed to clarify the role of natriuretic peptides in predicting and stratifying pregnancy complications.