THE EFFECT OF NIFEDIPINE AND METHYLDOPA ON MATERNAL CEREBRAL-CIRCULATION

Objective To study how the treatment of severe gestational hypertensio n affects maternal middle cerebral artery velocimetry. Design Prospect ive, clinical, descriptive study. Setting John Radcliffe Maternity Hos pital, Oxford, England. Participants Pregnant and puerperal women who required acute or chronic antihypertensive treatment with nifedipine ( n = 46) or methyldopa (n = 26), respectively. Methods Transcranial Dop pler ultrasound examinations of maternal middle cerebral arteries were performed before and 45 min after nifedipine; and before and 48 hours after the onset of methyldopa therapy. Blood pressure and heart rate were also recorded. Main outcome measures Clinical and transcranial Do ppler changes induced by the antihypertensive medication. Results Bloo d pressure and middle cerebral artery velocities decreased significant ly following bath short- and long-acting antihypertensive therapy. Nif edipine-induced changes were more pronounced and uniform than those fo und after methyldopa (16.7% and 6.4% decrease in middle cerebral arter y mean velocity, respectively). The middle cerebral artery mean veloci ty decrease was independent of changes in the blood pressure or heart rate. Conclusions Maternal cerebral haemodynamics are influenced by an tihypertensive treatment. The reduction of middle cerebral artery flow velocities following administration of nifedipine and methyldopa may suggest that cerebral vasodilatation is occurring, which is consistent with the concept that cerebral vasospasm is present in women with pre -eclampsia. The cerebral vasodilatation could result from a direct eff ect of the medication on the arteries in question.