Background-Little information is available about changes in left ventricula
r diastolic function during pregnancy. We used mitral inflow and pulmonary
venous flow profiles to evaluate left ventricular diastolic function in 37
healthy pregnant women 26 to 41 years old (mean, 32 years).
Methods and Results-Echocardiographic studies were performed at the end of
each trimester. Eight subjects (control group) underwent similar testing 1
to 3.5 months (mean, 1.7 months) postpartum. During pregnancy, the cardiac
output increased significantly as a result of an increased heart rate and,
to a lesser degree, stroke volume. Significantly decreased systemic vascula
r resistance and increased left ventricular mass were also noted. Peak mitr
al flow velocity in early diastole (E) increased 13.3% during the first tri
mester and remained at the high end of normal throughout pregnancy. Peak A-
wave velocity (A) increased maximally in the third trimester. Compared with
control subjects, first-trimester subjects had a significantly increased E
/A ratio. The ratio subsequently decreased, reflecting the augmented A-wave
velocity. Pulmonary venous peak systolic forward flow velocity increased,
peaking in the second trimester (nonsignificant), but returned to baseline
levels postpartum. The pulmonary venous diastolic time-velocity integral de
creased significantly from the first to the third trimester. Peak pulmonary
venous reverse flow velocity at atrial contraction increased significantly
, without being markedly changed in duration.
Conclusions-Pregnancy, a chronic, natural volume-overload state, has import
ant effects on hemodynamic and echocardiographic variables. Based on pulmon
ary venous flow and left ventricular inflow velocities, our results provide
a standard reference concerning diastolic filling dynamics by trimester.