Cardiac function, myocardial mechano-energetic efficiency, and ventricular-arterial coupling in normal pregnancy

To assess cardiac function, myocardial mechanoenergetic efficiency (MEE), and ventricular-arterial coupling (VAC) longitudinally during normal pregnancy, and to study if there was an association between cardiac structure and function, and fetal growth.

Cardiac structure and function, MEE, and ventricular-arterial coupling was assessed longitudinally in 52 healthy nulliparous women at 14, 24, and 34 weeks' gestation and 9-month postpartum.

Left atrial diameter increased during pregnancy (30.41 ± 3.59 mm in the nonpregnant state and 31.02 ± 3.91, 34.06 ± 3.58, and 33.9 ± 2.97 mm in the first, second, and third trimesters, P < 0.001). Left ventricular mass increased 117.12 ± 45.0 g in the nonpregnant state and 116.5 ± 33.0, 126.9 ± 34.5, 128.4 ± 36 g in the first, second, and third trimesters (P < 0.001). Cardiac output increased from 3.4 ± 1.2 l/min to 4.3 ± 0.7 l/min in the second and third trimesters (P < 0.001). Diastolic function decreased as both E/A and e'/a' decreased during pregnancy (P < 0.05 and P < 0.001, respectively). MEE and VAC were retained during pregnancy. Heart rate was associated with birth weight centile in the first (r = 0.41, P = 0.002) and second (r = 0.46, P = 0.002) trimester.

The increase in cardiac output during normal pregnancy is obtained by an increase in heart rate, followed by structural cardiac changes. The impaired systolic function is accomplished by a deteriorated diastolic function. Despite these rapid changes, the myocardium manages to work efficient with a preserved MEE. Cardiac and arterial adaption to pregnancy seems to appear parallel as evidenced by a preserved VAC.