Abnormal transcranial Doppler pattern in a pregnant woman during orthostatic hypotension

The effect of nifedipine and methyldopa on maternal cerebral circulation

OBJECTIVE

To study how the treatment of severe gestational hypertension affects maternal middle cerebral artery velocimetry.

DESIGN

Prospective, clinical, descriptive study.

SETTING

John Radcliffe Maternity Hospital, 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 Doppler 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 Doppler changes induced by the antihypertensive medication.

RESULTS

Blood pressure and middle cerebral artery velocities decreased significantly following both short- and long-acting antihypertensive therapy. Nifedipine-induced changes were more pronounced and uniform than those found after methyldopa (16.7% and 6.4% decrease in middle cerebral artery mean velocity, respectively). The middle cerebral artery mean velocity decrease was independent of changes in the blood pressure or heart rate.

CONCLUSIONS

Maternal cerebral haemodynamics are influenced by antihypertensive 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 effect of the medication on the arteries in question.

Detection of reverse flow by duplex ultrasonography in orthostatic hypotension

BACKGROUND AND PURPOSE

The aim of this study is to elucidate the effect of orthostatic hypotension on changes in cerebral blood flow.

METHODS

Blood flow velocities of both the common carotid artery and vertebral artery were measured using duplex ultrasonography in 12 patients: 6 with familial amyloidotic polyneuropathy, 3 with Shy-Drager syndrome, 2 with pandysautonomia, and 1 with senile orthostatic hypotension. Simultaneously, peripheral blood flow was also evaluated by laser-Doppler flowmetry.

RESULTS

The patients showing dizziness or syncope when tilted to a 70 degrees upright position exhibited characteristic reverse flow at the end-diastolic phase on the Doppler flow image of both the common carotid and vertebral arteries, which was effectively treated by infusion of 2.5 micrograms/min norepinephrine for 10 minutes. This end-diastolic reverse flow was not seen in any patients who did not have dizziness or syncope. After subjects were tilted from a supine to a 70 degrees upright position, decrease in the peripheral blood flow of the patients with orthostatic hypotension remained unchanged for at least 5 minutes, whereas that of control subjects was recovered within 2 minutes. However, no significant difference between the patients with and without clinical symptoms was observed.

CONCLUSIONS

These results suggest that detection of this specific echographic pattern may be quantitatively useful in examination of clinical symptoms accompanying orthostatic hypotension and that duplex ultrasonography may be a helpful tool to evaluate the effect of drugs used for controlling these clinical signs.