Low-flow mediated constriction as a marker of endothelial function in healthy pregnancy and preeclampsia: A pilot study

Abstract Objectives Overwhelming clinical evidence exists on disturbed vascular and endothelial function in the pathophysiology of preeclampsia (PE). In a non-pregnant (NP) population, L-FMC (low-flow mediated constriction) provides insight in the ‘resting’ endothelial capacity in contrast to the gold standard of flow mediated dilatation (FMD), reflecting endothelial nitric oxide bioavailability. Study design Longitudinal follow-up of 100 healthy pregnant (HP) women, 33 PE women and 16 NP controls with non-invasive vascular assessments. HP women were evaluated at 12 and 35 weeks of gestation and at 6 months postpartum. PE patients were assessed at diagnosis (mean 30 weeks) and 6 months postpartum. Main outcome measures. Endothelial function (L-FMC, FMD, peripheral arterial tonometry (PAT)) and arterial stiffness (pulse wave velocity (PWV) and analysis (PWA)) were measured at the different visits and compared between groups. Results Overall endothelial dysfunction is present in PE (FMD HP 9.09 ± 4.20 vs PE 5.21 ± 4.47, p = 0.0004; L-FMC HP −1.90 ± 2.66 vs PE −0.40 ± 2.09, p = 0.03). L-FMC gradually elevates during the course of a HP (1st trim −0.31 ± 1.75 vs 3rd trim −1.97 ± 3.02, p   0.05). Conclusion PE is characterized by dysfunction of both resting and recruitable endothelial capacity. This study offers new insights in different aspects of endothelial function in pregnancy, since L-FMC reflects an adaptation in HP that is absent in PE.