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

Abstract

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