Cardiovascular responses to the change from the left lateral to the upright position in pregnant hypertensives.

OBJECTIVES

To evaluate by non-invasive means, the autonomically mediated changes in heart rate and blood pressure in response to postural change in pregnancy.

METHODS

Ninety-one patients were studied, of whom 17 were non-pregnant controls, 21 were normotensive parturients, 22 had non-proteinuric hypertension, and 31 were pre-eclamptics. In all patients the heart rate and blood pressure response to the change from the left lateral to the erect position was measured non-invasively, during the third trimester in the pregnant groups.

RESULTS

The change from the left lateral to the erect position induced significantly greater mean changes (increases) in systolic blood pressure in the normotensive pregnant (PC) women than all other groups (P<0.05). Pre-eclamptic patients (PE) exhibited significantly less of an increase in systolic blood pressure than the non-proteinuric hypertensive (H) group. Both the H and PC groups showed significantly greater increases in diastolic pressure than the non-pregnant (NP) group. PE patients had a significantly smaller increase in diastolic pressure than the H group. There were no significant differences between heart rate changes when comparing the PC, NP and H groups. The PE group exhibited a significantly greater increase in heart rate on adopting the erect position than all other groups.

CONCLUSIONS

Pre-eclamptics exhibit smaller changes in blood pressure than normotensive pregnant patients and non-proteinuric hypertensives on standing, while producing an exaggerated heart rate response, indicating altered autonomic compensatory mechanisms in these patients.