Cerebrovascular hemodynamics in pregnant women with mild chronic hypertension.
OBJECTIVE
To evaluate and compare the cerebrovascular autoregulation in pregnant normotensive and mild chronic hypertensive patients without preeclampsia.


METHODS
Transcranial Doppler ultrasound was used to measure peak, end-diastolic, and mean velocities in the middle cerebral arteries of 34 normotensive and 17 mild chronic hypertensive women in the third trimester of pregnancy. Measurements were performed in the left lateral position at baseline, during 5% CO(2) inhalation, and during an isometric handgrip test. Mean pulsatility index, resistance index, and cerebral perfusion pressure at each time were compared using 2-way repeated measures analysis of variance. Using an alpha error of 5%, the statistical power to identify differences in middle cerebral artery indices in response to the two maneuvers was at least 90% and 50% in comparison between the two groups. Significance was P <.05.


RESULTS
Pregnant women with mild chronic hypertension had higher baseline mean blood pressure but similar pulsatility index (0.73 versus 0.75), resistance index (0.50 versus 0.50), and cerebral perfusion pressure (59.9 versus 61.8 mm Hg) compared with normotensive pregnant women. Both maneuvers caused a significant reduction in pulsatility index and resistance index and higher cerebral perfusion pressure. No significant differences were noted in the response to either 5% CO(2) inhalation or isometric handgrip test between the two groups.


CONCLUSIONS
Pregnant women with mild chronic hypertension show normal cerebral vasomotor reactivity to CO(2) breathing and isometric handgrip. This suggests that the abnormal cerebrovascular autoregulation in preeclampsia is not directly linked to the elevated blood pressure but rather is determined by a separate pathophysiologic pathway.


METHODS
II-2
Riskin-Mashiah
Shlomit
S
Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas, USA. ariskin@newmail.net
Belfort
Michael A
MA
D000328:Adult; D001783:Blood Flow Velocity; D001795:Blood Pressure Determination; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000175:diagnosis*; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D017585:Ultrasonography, Doppler, Transcranial