Maternal Middle Cerebral Artery Research Articles

Maternal middle cerebral artery velocity changes in HELLP syndrome versus pre-eclampsia.

Our objective was to determine whether there is a difference in middle cerebral artery blood flow velocity in patients with the syndrome of hemolysis, elevated liver enzymes and low platelet counts (HELLP syndrome) compared to a matched controlled group of patients with pre-eclampsia and without HELLP syndrome. Six pre-eclamptic patients with HELLP syndrome and 12 pre-eclamptic women without HELLP syndrome had maternal middle cerebral artery blood flow velocity assessed antepartum and at 24 and 48 h postpartum. We compared the effect of the development of HELLP syndrome on middle cerebral artery blood flow velocity changes using non-parametric tests. Patients with HELLP syndrome showed no significant differences in diastolic, systolic, mean middle cerebral artery blood flow velocity or pulsatility index in either the antepartum or 24-h and 48-h postpartum phases when compared to non-HELLP pre-eclamptic patients. Our data suggest that there is no difference in the blood flow velocity waveform of the maternal middle cerebral artery between patients with pre-eclampsia and those with HELLP syndrome.

Maternal middle cerebral artery velocimetry in normal pregnancy and postpartum.

To study changes throughout gestation and the puerperium of middle cerebral artery flow velocity waveforms obtained by transcranial Doppler ultrasound. Prospective, observational study. John Radcliffe Maternity Hospital, Oxford, UK. Middle cerebral artery velocities were measured by transcranial Doppler ultrasound in 25 nonpregnant women, 22 women longitudinally followed throughout pregnancy and 21 women serially studied from delivery until the late puerperium. Transcranial Doppler changes in pregnancy and the puerperium. The transcranial Doppler ultrasound measurements showed good reproducibility. Signals from one middle cerebral artery could not be obtained in 4.6% of the examinations, but otherwise readings were similar on both sides. Women in the second half of pregnancy had lower middle cerebral artery mean velocities than nonpregnant women. Velocities decreased with advancing gestation but increased in the immediate puerperium to levels comparable to those found in nonpregnant women. Transcranial Doppler ultrasound is a noninvasive technique suitable for studying maternal cerebral haemodynamics in pregnancy and postpartum. Middle cerebral artery mean velocity decreased with advancing gestation and increased to nonpregnant values in the immediate puerperium. These physiological changes need to be considered when comparing data with measurements taken in abnormal pregnancy states.

The effect of nifedipine and methyldopa on maternal cerebral circulation.

To study how the treatment of severe gestational hypertension affects maternal middle cerebral artery velocimetry. Prospective, clinical, descriptive study. John Radcliffe Maternity Hospital, Oxford, England. Pregnant and puerperal women who required acute or chronic antihypertensive treatment with nifedipine (n = 46) or methyldopa (n = 26), respectively. 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. Clinical and transcranial Doppler changes induced by the antihypertensive medication. 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. 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.

Transcranial doppler findings of cerebral vasospasm in preeclampsia

The objective of this study was to evaluate the effect of preeclampsia and its severity on maternal mean middle cerebral artery blood flow velocity (mean MCA-CBFV) using transcranial doppler sonography (TCD), as well as the effect of magnesium on mean MCA-CBFV in preeclampsia. This study used a prospective, comparative design. TCD was used to examine maternal mean MCA-CBFV in both healthy subjects (controls) and preeclamptic subjects (cases). The two groups were similar in age, gestational age, and parity. Healthy subjects were categorized into three groups: Group I, 6-14 weeks, n = 10; Group II, 24-40 weeks, n = 27; Group III, postpartum n = 15, 12-36 h. Serial TCD examinations of the middle cerebral artery were completed in 21 preeclamptic subjects at four different points in time: Time I is an initial measurement before delivery; Time 2 is also before delivery but after magnesium had been administered. Time 3 is postpartum while on magnesium (12-24 h), Time 4 is postpartum off magnesium, (24-48 h). Preeclamptic subjects had significantly increased mean MCA-CBFV when compared to healthy subjects: antepartum (mean 78.2 vs. 55.1 cm/sec, P < 0.0005); postpartum (mean 101.3 vs. 69.8 cm/sec, P < 0.0001). Severe preeclamptics had significantly higher mean MCA-CBFV than mild preeclamptics at each point in time: Time 1: P < 0.016; Time 2: P < 0.040; Time 3: P < 0.002; and Time 4: P < 0.028. These data support the theory that cerebral vasospasm of the smaller diameter vessels is a major component of preeclampsia.

Randomised study assessing the effect of phenytoin and magnesium sulphate on maternal cerebral circulation in eclampsia using transcranial Doppler ultrasound

To assess maternal middle cerebral artery flow velocity patterns as measured by transcranial Doppler ultrasound (TCD) in eclampsia and to investigate the effect of the anticonvulsants magnesium sulphate (MgSO4) and phenytoin on cerebral circulation. Prospective randomised study. High care obstetric unit, King Edward VIII Hospital, Durban, South Africa. Twenty-four eclamptic patients: 13 received MgSO4 and 11 phenytoin. Middle cerebral artery flow velocity waveforms were measured using 2 MHz pulsed Doppler ultrasound via the transtemporal approach in eclamptic patients, before and 15 minutes after the loading dose of anticonvulsant. Magnesium sulphate significantly reduced the pulsatility index (P = 0.002) and mean flow velocity (P = 0.02) in the middle cerebral artery, whereas phenytoin failed to produce any statistically significant effect. However, differences between groups were not statistically significant. Systolic and diastolic blood pressures were reduced in both the MgSO4 and phenytoin groups. These findings provide firm evidence that MgSO4 relieves cerebral vasospasm, compared with phenytoin, and may therefore be the better drug for the prevention of eclamptic convulsion.

The effect of magnesium sulfate on maternal and fetal blood flow in pregnancy‐induced hypertension

The purpose of this study was to evaluate the effects of magnesium sulfate on maternal and fetal blood flow in pregnancy-induced hypertension. Twelve patients with pregnancy-induced hypertension were prospectively studied with transcranial pulsed Doppler and transabdominal color flow Doppler before and after infusion of a 6 gram intravenous loading dose of magnesium sulfate. The maternal vessels studied included the middle cerebral, common carotid, and internal carotid arteries. The fetal vessels studied included the middle cerebral, renal, and umbilical arteries. In addition the maternal circulation in the placental base plate was imaged. The results of this descriptive study suggest that a 6 gram loading dose of magnesium sulfate significantly vasodilates the vascular bed distal to the maternal middle cerebral artery, and increases blood velocity in this distribution. There was no significant change in pulsatility index or blood velocity in the central large vessels of the head and neck. There were no acute effects noted in the fetal or placental vessels evaluated.

Noninvasive assessment of the maternal cerebral circulation by transcranial Doppler ultrasound during angiotensin II infusion.

To examine the relationship between experimentally induced increments in blood pressure and maternal middle cerebral artery flow velocity patterns measured by transcranial Doppler ultrasound (TCD). Prospective experimental study. John Radcliffe Maternity Hospital, Oxford. Middle cerebral artery flow velocity waveforms were measured using 2 MHz pulsed Doppler ultrasound via the temporal cranial approach at 28 weeks gestation before, during and 10 min following an angiotensin II infusion. 101 normotensive primiparous women at 28 weeks gestation. A significant rise in blood pressure and fall in heart rate were demonstrated between pre-infusion and maximum angiotensin II infusion (maximum blood pressure) recordings. Simultaneous changes were observed in all flow velocity indices, shown as a decrease in systolic velocity and pulsatility index, and an increase in diastolic and mean velocity (P < 0.0001). These values all returned to baseline levels 10 min post infusion (P < 0.0001). Statistical analysis suggested that the change in flow velocity is related to the rise in blood pressure rather than the direct effect of angiotensin II on the cerebral circulation. Transcranial Doppler can detect changes in the cerebral circulation associated with alterations in blood pressure during pregnancy. The technique needs to be evaluated further in hypertensive disease.