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The aortic diameters of 89 normotensive pregnant women were compared with those of nine rigorously defined preeclamptic women and 59 women who required antihypertensive therapy. Over the course of normal pregnancy, the diameter increased significantly; it was larger in preeclamptic than in normotensive women throughout pregnancy. The aortic diameter in women with high-resistance hypertension was smaller than that in normotensive women and in those with high-output, low-resistance hypertension, but it was larger in women with low-resistance hypertension than in normotensive women. The aortic diameter increased after treatment of high-resistance hypertension with hydralazine, but decreased after treatment of high-output, low-resistance hypertension.

Preeclampsia is a disease unique to pregnancy that contributes substantially to maternal and fetal morbidity and mortality. The condition has been thought to be one of hypoperfusion in which increased vascular resistance characterizes the associated hypertension. This study was designed to test an alternative hypothesis, that preeclampsia is characterized by high cardiac output. In a blinded longitudinal study of nulliparas with uncomplicated pregnancies, cardiac output was measured serially by Doppler technique. Cardiac output was elevated throughout pregnancy in patients who became preeclamptic (P = .006). Six weeks postpartum, the hypertension of the preeclamptic subjects had resolved but cardiac output remained elevated (P = .001) and peripheral resistance remained lower than in the normotensive subjects (P = .001). This study demonstrates that preeclampsia is not a disease of systemic hypoperfusion and challenges most current models of the disease based on that assumption.

Preeclampsia is a common disease and as such is a significant contributor to maternal and neonatal morbidity and mortality. Despite the ubiquity of the disease and its public health impact, no comprehensive mechanism has been established. Therapy has been limited to bed rest and premature delivery. The purpose of this article is to examine preeclampsia from a hemodynamic point of view and to advance a hypothesis of disease mechanism.

In 12 patients requiring pulmonary artery catheterization, cardiac output was measured using Doppler and thermodilution techniques. The Doppler technique accurately predicted measurements made by thermodilution (r = 0.91; P less than .001). Eighteen normal patients in the third trimester and 36 preeclamptics who had not been treated with medications other than magnesium sulfate were evaluated with Doppler alone. Of note was the heterogeneity among preeclamptics. Although their mean systemic vascular resistance was elevated, it ranged from 2256-648 dyne X sec X cm-5. Cardiac output ranged from 13.2-3.9 L/minute.

To assess the effects of hydrostatic pressure on the interpretation of the supine pressor test (SPT), blood pressure (BP) measurements were made with a mercury sphygmomanometer in 35 normotensive primigravid patients between 28 and 32 weeks' gestation. BP was recorded in both left lateral recumbent and supine positions. Blood pressure was also recorded in both arms simultaneously by separate observers. A positive supine pressor test was defined as a diastolic BP rise of 20 mm Hg. There were no positive SPTs when BP was recorded in the lower arm despite the development of preeclampsia in eight patients. When BP was corrected for the hydrostatic effect of position, no correlation was seen between position change and blood pressure (p greater than 0.05). Diastolic BP was significantly higher (p less than 0.01) in patients who later developed preeclampsia than in patients who remained normotensive.

Ten patients with severe pre-eclampsia were studied throughout labor and delivery and during the early puerperium with a flow-directed pulmonary artery catheter. Cardiac output was higher than previously described in normal patients. Pulmonary artery pressures were not significantly altered from the normal pregnant values. The usual increase in cardiac output occurring in the early puerperium was not observed in the patients with severe pre-eclampsia. Central venous pressure and pulmonary artery wedge pressure did not correlate in three of the nine patients studied. Left ventricular stroke work index was elevated in the patients with severe pre-eclampsia, suggesting a hyperdynamic state. The pulmonary artery catheter provided important new information in patients with severe pre-eclampsia and may be a useful clinical adjunct in patients with hemorrhage or oliguria and in patients needing a regional or general anesthetic.

Ten patients with severe preeclampsia complicated by pulmonary edema were studied with invasive hemodynamic monitoring. Eight of 10 patients developed pulmonary edema during the postpartum period. Five patients had alterations in the colloid osmotic pressure--pulmonary artery wedge pressure gradient related to elevations in the pulmonary artery wedge pressure and a reduction in the colloid osmotic pressure. Three patients had hemodynamic findings consistent with pulmonary capillary leak. Two patients had evidence of left ventricular failure. In three of the patients, the central venous pressure was significantly lower than the simultaneously determined pulmonary artery wedge pressure during the acute phase of the pulmonary edema.