Autonomic Hemodynamic Control in Pregnancy-Induced Hypertension

Abstract

Objective: To elucidate the role of the parasympathetic and sympathetic control of circulation in pregnancy-induced hypertension (PIH) and to investigate whether the short-term regulation of blood pressure is disturbed in PIH.

Methods: The Valsalva maneuver, the deep breathing test, the active orthostatic test, and the isometric handgrip test were used to study the autonomic circulatory control in 14 patients with PIH and 14 healthy pregnant controls. The Finapres® method was used to assess blood pressure continuously and noninvasively during the tests.

Main Outcome Measures: The heart rate and blood pressure responses to standard cardiovascular reflex tests.

Results: The Valsalva maneuver reduced the systolic blood pressure significantly more in PIH than in healthy pregnant controls (-19% vs. -10%, P = 0.02). In the orthostatic test the rise in diastolic blood pressure (20% vs. 29%, P = 0.03) and in the heart rate (19 bpm vs. 24 bpm, P = 0.05), and the max/min ratio (1.31 vs. 1.48, P = 0.04) were smaller in the PIH group.

Conclusion: The changes in blood pressure and heart rate responses indicate that the autonomic control of hemodynamics is disturbed in PIH. The regulation of the sympathetically mediated peripheral vasoconstriction is impaired and the baroreflex sensitivity may be decreased.

Key Words:

• Autonomic nervous system
• Cardiovascular reflex test
• Finapres®
• Pregnancy