NONINVASIVE DETECTION OF THE MORPHOLOGICAL AND HEMODYNAMIC-CHANGES DURING NORMAL-PREGNANCY

To characterize the morphologic and hemodynamic changes during normal pregnancy, serial echocardiographic measurements (n = 210) of left ventricular (LV) dimensions and mass (M-mode), volumes and ejection fraction (two-dimensional), stroke volume, and cardiac output (Doppler: aortic, apical, and suprasternal) were performed in 15 patients (mean age 30 years) beginning as early as 12 weeks of gestation, at 2-week intervals through delivery, and up to 12 weeks postpartum. Left atrial size increased from 3.4 +/- 0.4 (SD) to 3.8 +/- 0.4 cm near term, decreasing to 3.4 +/- 0.5 cm postpartum (p = 0.006 overall). LV mass changes correlated with increases in body weight. No consistent significant changes in LV volumes and ejection fraction were observed. LV outflow tract cross-sectional area increased significantly from 3.0 +/- 0.2 cm2 at baseline to 3.5 +/- 0.3 cm2 near term, decreasing to 3.2 +/- 0.3 cm2 postpartum (p < 0.002 for both). Heart rate increased from 70 +/- 7 to 77 +/- 10 beats/min near term decreasing to baseline postpartum (p < 0.02 for both). Accordingly, cardiac output increased significantly, as detected from both the apical and suprasternal positions averaging from 4.7 +/- 0.6 to 6.5 +/- 1.5 l/min near term, returning to 4.3 +/- 0.6 l/min postpartum (p < 0.0005 for both). Thus, in normal pregnancy, left atrial size increases significantly without significant changes in LV dimensions, volumes, and ejection fraction. Increased LV mass is related to increased body weight. Cardiac output changes result from increased heart rate and an increase in LV outflow area, which contributes to increased stroke volume. Doppler echocardiography permits accurate detection and timing of the morphologic and hemodynamic changes during normal pregnancy.