Effects of a natural volume overload state (pregnancy) on left ventricular performance in normal human subjects.

Abstract

To assess the effects of a natural volume overload state (pregnancy) on left ventricular function we recorded echocardiograms each trimester (TM) and four to 12 weeks postpartum. Heart rate increased from 77 ± 2 (SEM) to 88 ± 2 heats/min (TM I vs TM 3, P < 0.01) and declined to 69 ± 2.0 beats/min postpartum (P < 0.05 vs TM 3). Despite these changes, end-diastolic dimension increased from 46.3 ± 0.7 to 50.7 0.7 mm (TM I vs TM 3, P < 0.01) and decreased postpartum to 47.5 ± 0.7 mm (P < 0.01 vs TM 3). Calculated stroke volume and cardiac index changed correspondingly, but ejection fraction, percent of fractional shortening and mean normalized rate of internal diameter shortening were not significantly altered. Left ventricular wall mass increased during gestation but decreased between TM 3 and postpartum 162 ± 8.3 vs 143 ± 6.2 g, P < 0.05). THE OPTIMAL MANAGEMENT of pregnancy, especially for women with heart disease, requires an understanding of the basic hemodynamic stresses that occur during gestation. The most important hemodynamic change in the maternal circulation during pregnancy is an increase in cardiac output of 30-40%.' This alteration has several unique features: 1) the augmentation occurs relatively early in pregnancy (20-24 weeks), 2) it cannot be explained entirely on the basis of fetal needs, and 3) fluctuations in cardiac output occur with changes in body position as the gravid uterus impinges in varying degree on the inferior vena cava, thus altering systemic venous return.2 A second fundamental hemodynamic change is a decrease in peripheral vascular resistance as a consequence of the creation of a low-resistance circuit (placenta). This alteration is manifest as a widened pulse pressure due to a decline in levels of diastolic arterial blood pressure and a fall in mean blood pressure.3 A third hemodynamically important shift during pregnancy is a dramatic increase in maternal blood volume approaching 40% above nonpregnant values.4While the effects on cardiac output have been welldocumented, there is conflicting information concerning left ventricular performance during pregnancy. Normal, augmented and depressed function have been reported at various stages of gestation."' In addition, normal gestation provides the opportunity to study a naturally occurring volume overload state in normal human subjects. This study was designed to provide quantitative information regarding serial alterations in left ventricular performance during normal pregnancy. Methods Study DesignThe study group was comprised of 19 pregnant women who had normal, full-term spontaneous deliveries. They were 19-37 years of age (mean = 25) and had no cardiovascular disease as assessed by a complete history and physical examination. The resting electrocardiogram was within normal limits in all subjects. All subjects underwent identical procedures at the end of the first and second trimesters and during the third trimester within one to two weeks before the expected date of delivery and six to 12 weeks postpartum. At each visit the f...

Alterations of left ventricular function in women with insulin-dependent diabetes mellitus during pregnancy

“…The left ventricular enddiastolic and endsystolic dimensions did not change during or after pregnancy. This result of our study agrees [6] and differs from those of other investigators [1,5]. The slight increase in atrial size during pregnancy has already been documented [1] and it was interpretated as an indirect indicator of the left ventricular filling status.…”

“…Other studies, however, described an unchanged left ventricular ejection fraction during the entire course of pregnancy [5,20]. The left ventricular enddiastolic and endsystolic dimensions did not change during or after pregnancy.…”

“…namic parameters in the maternal cardiovascular system were evaluated noninvasively by echocardiography [2,3]. In earlier studies, echocardiography was frequently applied in order to describe left ventricular systolic function and cardiac haemodynamics during pregnancy [1,4,5,6,7,8], since it allows assessment of cardiac haemodynamics without endangering the pregnancy. However little data on left ventricular diastolic function during pregnancy has been assessed.…”

Left Ventricular Concentric Geometry as a Risk Factor in Gestational Hypertension

“…This hemodynamic feature has been already reported in essential hypertension by Ganau et al 2 Furthermore, in the past a progressive eccentric left ventricular enlargement with a decreased ratio between posterior wall thickness and left ventricular end-diastolic diameter was reported in normal pregnancy. 26 Normal geometry and eccentric hypertrophy probably represent the adequate cardiac adaptation in GH pregnancies in response to a plasma volume expansion. Patients with concentric geometry are those with pressure overload and volume underload, as they show the highest TVR and the lowest stroke volume.…”

Alterations in Heart Rate and Atria to Ventricular Conductivity in Third Trimester Pregnancy: A Comparative Study

“…There is evidence from various studies to suggest that some electrocardiographic parameters are, indeed, altered in the pregnant state [4]- [8]. According to the study conducted upon pregnant women, Katz et al (1978) reported that the heart rate increased throughout pregnancy and reached to a peak in third trimester [9]. Similarly, this increase in heart rate was not purely linear but slightly curved according to Carla et al [10].…”