Vascular reactivity in patients with preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome

OBJECTIVE: Early structural and functional changes in the systemic vasculature have been proposed to play a major pathogenetic role in preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome. The aim of the study was to determine vascular reactivity in patients with preeclampsia with and without HELLP syndrome with respect to those in healthy pregnant control subjects. STUDY DESIGN: Forearm blood flow was measured by strain gauge plethysmography with the venous occlusion technique in 12 hypertensive patients with HELLP syndrome, in 8 patients with preeclampsia without HELLP syndrome, and in 8 healthy normotensive pregnant control subjects. To determine vascular reactivity the forearm blood flow was measured at baseline and after forearm occlusion for a period of 5 minutes (reactive hyperemia). The investigations were repeated 4 to 6 months post partum. Forearm vascular resistance was calculated as the ratio of mean arterial pressure to forearm blood flow. RESULTS: Mean arterial pressure at rest was elevated in patients with preeclampsia (116 +/- 20 mm Hg) and in patients with HELLP syndrome (110 +/- 16 mm Hg) with respect to healthy pregnant control subjects (86 +/- 10 mm Hg; P<.05). Forearm blood flow at rest was not statistically different in patients with preeclampsia (5.1 +/- 2.6 mL/min per 100 mL) and with HELLP syndrome (4.7 +/- 1.5 mL/min per 100 mL) with respect to pregnant control subjects (5.9 +/- 3.1 mL/min per 100 mL), however, forearm vascular resistance at rest was elevated in patients with preeclampsia (25.9 +/- 9.5 units; P <.05) and in patients with HELLP syndrome 124.6 +/- 6.9 units; P<.05) with respect to healthy control subjects (17.0 +/- 6.1 units). During reactive hyperemia the peak forearm blood flow, which is an indicator of maximal vasodilatory capacity, was impaired in patients with preeclampsia (21.9 +/- 8.2 mL/min per 100 mL; P <.05) but not in patients with HELLP syndrome (37.4 +/- 17.5 mL/min per 100 mL) and healthy control subjects (44.9 +/- 15.0 mL/min per 100 mL). Consequently. minimum forearm Vascular resistance was higher in women with preeclampsia (6.1 +/- 1.9 units) than in both women with HELLP syndrome (3.5 +/- 1.6 units) and the control subjects (2.8 +/- 2.4 units). CONCLUSION: Despite similarly elevated forearm vascular resistances at rest in patients with HELLP syndrome and in patients with preeclampsia, forearm vascular resistance during reactive hyperemia did not differ significantly from that in healthy control subjects in the women with HELLP syndrome but was increased in women with preeclampsia. Vasodilatory reactivity thus is reduced in preeclampsia but not in HELLP syndrome. which suggests different alterations of the vasculature.