Introduction: The number of pregnant women with congenital heart disease (CHD) is increasing. Validation of non-invasive techniques to monitor cardiac output (CO) in this population is needed. Uteroplacental blood flow, impaired in women with CHD, is associated with their cardiac function. B-type natriuretic peptide (BNP), cytokines and cellular adhesion molecules (CAMs) could provide insight into the higher adverse pregnancy/cardiovascular events in women with CHD.
Methods: Low-risk pregnant women (LR-group) and pregnant women with CHD (CHD-group) were seen in each trimester. Visits included blood sampling for BNP, cytokine/CAM analyses and measurement of haemodynamic parameters at T1-rest, T2-immediately after exercise and T3-after recovery, simultaneously with transthoracic echocardiography (TTE) and impedance cardiography (PhysioFlow®). Fetal growth and Doppler studies performed in the third trimester.
Results: PhysioFlow® showed good trending ability (LR-group: concordance rate-CR=95.4%, angular bias=4.5o; CHD-group: CR=100%, angular bias=4.1o). Their blood pressure profile followed a J-shape pattern, heart rate increased, peripheral oxygen saturations decreased and CO remained stable with advancing gestation. No association found between uterine artery Doppler and CO/ΔCO or mean arterial pressure in either group. Umbilical artery Doppler was negatively associated with birthweight (BW-p=0.004, BW centile-p=0.006), as was the cerebroplacental ratio (BW-p=0.002, BW centile-p=0.003) in the LR-group. BNP decreased throughout pregnancy, without significant differences between groups. IL-6 was higher in the CHD-group (p=0.005) in the first trimester, IL-10 lower in the third trimester (p=0.018). High levels of IL-6 in the first trimester were associated with lower BW (p=0.002, BW centiles-p=0.020). Higher ICAM in the CHD-group in the first trimester was associated with lower BW (p=0.002, BW centiles-p=0.006).
Conclusion: PhysioFlow® can be used in low-risk pregnancy to study trends in CO. BNP decreased throughout pregnancy in both groups. The proinflammatory cytokine profile in women with CHD could explain the higher incidence of adverse outcomes, although more research is needed.