Maternal cardiac function, uterine artery hemodynamics and natriuretic peptides at 22-24 weeks of gestation and subsequent development of hypertensive disorders of pregnancy

Abstract

<p><i>Introduction - </i>Maternal cardiac dysfunction as well as abnormal uterine artery (UtA) Doppler are associated with hypertensive disorders of pregnancy (HDP), but their relation is unclear. We investigated the correlation between maternal cardiac function, UtA hemodynamics and natriuretic peptides, and explored differences between women who subsequently developed HDP and those who did not. <p><i>Material and methods - </i>This was a prospective cross‐sectional cohort study of 347 pregnant women at 22‐24 weeks. Maternal cardiac function and systemic hemodynamics were investigated at baseline and after 90 seconds of passive leg raising using impedance cardiography. Preload reserve was defined as percent change (Δ%) in stroke volume and cardiac output from baseline to passive leg raising. UtA hemodynamics was studied using Doppler ultrasonography. UtA blood flow, resistance and pulsatility index were calculated. Fasting venous blood samples were analyzed for natriuretic peptides (pro atrial natriuretic peptide [proANP], N‐terminal pro brain natriuretic peptide [Nt‐proBNP] and C‐type natriuretic peptide [CNP]). The course and outcome of pregnancy were recorded. <p><i>Results - </i>At baseline, ProANP correlated significantly with cardiac output (r = −0.122; P = .023) and left cardiac work index (r = −0.112; P = .037), whereas Nt‐ProBNP correlated significantly with acceleration index (r = .127; P = .018) and velocity index (r = −0.111; P = .039. CNP correlated significantly with UtA blood flow (r = .118; P = .028) and resistance (r = −0.112; P = .037) but not with UtA pulsatility index (r = .034; P = .523). None of the natriuretic peptides correlated with preload reserve. At 22‐24 weeks, women who subsequently developed HDP had lower UtA blood flow (552 vs 692 mL/min; P = .028), higher UtA resistance (0.28 vs .17 mmHg/mL/min; P = .004) and higher mean UtA pulsatility index (1.12 vs .84; P < .001) compared with those who did not; however, the natriuretic peptide levels were similar in the two groups. Women developing HDP had a significantly higher increase in stroke volume and cardiac output and more reduction in systemic vascular resistance following passive leg raising compared with the reference group. Left cardiac work index, acceleration index and velocity index decreased following passive leg raising in the reference group but increased in women who later developed HDP. <p><i>Conclusions - </i>ProANP correlated with cardiac output and cardiac work, Nt‐proBNP with indices of cardiac contractility, and CNP with UtA blood flow and resistance. None of these natriuretic peptides measured at 22‐24 weeks of gestation reflected cardiac preload reserve or predicted development of HDP.