Impaired vasoconstriction in pregnancy-induced hypertension assessed using Doppler fluximetry

Abstract

Objective: To determine whether there is a difference in peripheral vascular reactivity between normal women and those with pregnancy-induced hypertension. Methods: Capillary blood flow (flux) was recorded in the skin over the ankle in 26 pregnant women with pregnancy-induced hypertension at term. Twelve of these women had proteinuria, and 14 were nonproteinuric. Leg lowering was used to activate the venoarteriolar reflex, and the resultant change in flux, expressed as a percentage change from the baseline, was used as an index of vascular reactivity. The results were compared with those of a control group comprising 23 matched normotensive women. The study was repeated on all of the women after delivery. Results: Women with hypertension showed a median (range) increase in flux of +24.4% (−15.5% to +151.1%), significantly different from controls: −39.3% (−80.9% to −4.3%, P < .001). This difference persisted regardless of the presence or absence of proteinuria. Responses in women with pregnancy-induced hypertension were significantly different after delivery (median −60.7%; range −158.5% to −19.5%, P < .001) when compared with predelivery responses. Similar changes as a result of delivery were seen in women with proteinuric (medians +25.9% and −57.9%, P < .002) and nonproteinuric (medians +7.8% and −62.8%, P < .001) hypertension but not in controls. Postdelivery responses in women with hypertension were no different from those of controls. Conclusion: Women with pregnancy-induced hypertension have abnormal cutaneous vascular reactivity that returns to normal after delivery.