Systemic Arterial Response and Ventriculo-Arterial Interaction During Normal Pregnancy

BACKGROUND During normal pregnancy (NP), cardiac output (CO) increases, and blood pressure and systemic vascular resistance are reduced. We wanted to evaluate systemic arterial properties and interaction between the left ventricle (LV) and systemic arteries during NP. The role of systemic arteries and their interaction with LV-function in this hemodynamic response, lack description. METHODS We used noninvasive methods to study 65 healthy women (32 +/- 5 years) with NP repeatedly at gestational weeks 14-16, 22-24, 36, and 6 months postpartum (PP). Aortic root pressure and flow were obtained by calibrated right subclavian artery pulse traces and aortic annular Doppler flow recordings. Arterial properties were described by estimates of total arterial compliance (C), proximal aortic stiffness (characteristic impedance (Z(0))), arterial elastance (Ea), and peripheral arterial resistance (R). Ventriculo-arterial coupling (VAC) was characterized by the ratio between arterial (EaI) and LV (ELVI) elastance index. RESULTS During NP, CO increased by 20% due to increased heart rate and stroke volume. Mean arterial pressure was reduced by 10% (P < 0.001) as compared to 6 months PP. R was reduced by 5% (P < 0.01), Z(0) trended lower and C higher. EaI decreased (P < 0.01) and ELVI was reduced to a higher extent resulting in 29% increase of EaI/ELVI during NP (P < 0.01). CONCLUSIONS During NP there is an increase in CO, and decrease in blood pressure and R whereas central aortic properties are less altered. The increased VAC index (EaI/ELVI) during NP indicates a decrease in LV-function not fully compensated for by vascular adaptation.