Cardiovascular hemodynamics throughout normal pregnancy and postpartum as measured by impedance cardiography

Abstract

Objective To evaluate the feasibility of non-invasive assessment of maternal cardiac and arterial characteristics throughout uncomplicated pregnancy and postpartum. Design A longitudinal evaluation throughout gestation, at seven weeks postpartum and at one year postpartum. Setting Antenatal outpatient clinic of Ziekenhuis Oost-Limburg (Genk, Belgium). Sample 16 women with uncomplicated pregnancy. Methods Impedance cardiography measurements were performed in supine, standing, and sitting position using a standard protocol with known reproducibility. SAS procedure MIXED for linear mixed models was used, and fitted to the data for each parameter separately: Data were binned in four-weekly intervals. Differences between gestational and postpartum measurements were evaluated by One-Sample Wilcoxon Signed Rank Tests. Data are presented as mean (standard error of mean). Main outcome measures Gestational and postnatal evolution of blood pressure, stroke volume, cardiac output, cardiac cycle time intervals, aortic flow characteristics, total peripheral vascular resistance, and thoracic fluid content. Results In all positions, stroke volume and cardiac output changed significantly throughout gestation (n=16; p≤0.0001), and supine values differed from standing (p≤0.008) and sitting positions (p≤0.048). As compared to early postpartum, all cardiovascular parameters remained unchanged after one year postpartum (n=12; p≥0.074), except for standing diastolic blood pressure which decreased with 5±2 mmHg (p=0.037). Conclusions Gestational evolutions of left ventricular output were similar to reported changes in literature, and were influenced by maternal position. Our study illustrates that impedance cardiography has the potential to become a useful tool in perinatal medicine to assess maternal hemodynamics