Middle Cerebral Artery Waveforms Research Articles

The prediction of estimated cerebral perfusion pressure with trans-systolic time in preterm and term infants.

It is important to monitor cerebral perfusion in infants because hypo- and hyperperfusion can contribute to neurological injury. This study aimed to clarify the relationship between trans-systolic time (TST) and critical closing pressure (CrCP) or estimated cerebral perfusion pressure (CPPe) in neonates. Moreover, we aimed to determine the TST values in preterm and term infants with stable cerebral perfusion to clarify normative reference data. This multicentre prospective study included infants with arterial lines admitted to the neonatal intensive care units between December 2021 and August 2023. TST, CrCP, and CPPe were calculated using middle cerebral artery waveforms recorded using transcranial Doppler ultrasonography when clinicians collected arterial blood samples. Three hundred and sixty samples were obtained from 112 infants with a gestational age of 32 (interquartile range, 27-37) weeks and a birth weight of 1481 (956-2355) g. TST was positively correlated with CPPe (r = 0.60, p < 0.001), but not with CrCP (r = 0.08, p = 0.10). The normative reference values of TST in preterm and term infants without samples of hyper- or hypocapnia and/or hyper- or hypotension, which may affect cerebral perfusion, were as follows: ≤ 29weeks, 0.12 (0.11-0.14) s; 30-36weeks, 0.14 (0.12-0.15) s; and ≥ 37weeks, 0.16 (0.14-0.17) s, respectively. Conclusion: TST in neonates significantly correlated with CPPe, but not with CrCP. TST may be a good predictor of cerebral perfusion and potentially have wider clinical applications. What is Known: •Trans-systolic time (TST) is used in evaluating the effects of increased intracranial pressure on cerebral haemodynamics. However, little is known about the efficacy of TST in predicting neonatal cerebral perfusion pressure. What is New: •This study added evidence that TST correlated with estimated cerebral perfusion pressure, but not with critical closing pressure. Additionally, we showed the normative reference values of the TST in preterm and term infants.

M-Sign in Middle Cerebral Artery Doppler Waveforms: A Sign of Fetal Vasoconstriction Before and After Open Fetal Spina Bifida Repair.

Increased pulse wave reflection in the fetal arterial system, illustrated by a second systolic peak (M-sign) in middle cerebral artery (MCA) Doppler waveforms, allows interpretation of fetal systemic vasoconstriction. Little is known about fetal vascular regulation during fetal spina bifida (fSB) repair. Therefore, the aim of this study was to analyze MCA-Doppler waveform changes before, during, and after fSB repair. 31 pregnant women who underwent fSB repair were included. Fetal MCA-Doppler waveforms were prospectively analyzed before, during and after fSB repair, and categorized as follows: normal systolic downslope, systolic shoulder, second systolic peak (M-sign), and concave systolic downslope. These MCA waveforms were related to maternal and fetal characteristics, to anesthetic medication, and to umbilical artery (UA) waveforms. Before fSB repair, all fetuses repeatedly presented M-signs. After initiation of desflurane for general anesthesia, systolic shoulder and the M-sign vanished in 24/31 (78%) fetuses and 19/31 (61%) showed transient UA ARED flow. A significant association between these two Doppler findings was found (p=0.007). After fSB repair, signs of increased pulse wave reflection reappeared but resolved over time (23 days ± 20, SD) in all fetuses. Both fSB and intrauterine repair influence fetal vascular regulation. This phenomenon can be illustrated by MCA-Doppler waveforms. While anesthetic agents transiently eliminated M-signs and often provoked a UA ARED flow, fSB repair finally led to normalization of MCA-Doppler waveforms indicating return to normal fetal vascular regulation.

VP51.01: The “M” sign: systolic middle cerebral artery waveform changes before, during and after fetal myelomeningocele repair

VP51.01: The “M” sign: systolic middle cerebral artery waveform changes before, during and after fetal myelomeningocele repair

Correlation Between Internal Carotid Artery Patency and Middle Cerebral Artery Waveform During CEA

The blunted signal distal to an arterial occlusion is a well-known phenomenon. Here we try to assess this entity, correlate it to different hemodynamic parameters and understand its modification in case of internal carotid artery (ICA) status.

Maternal sigara kullamının doppler ölçümleri üzerine etkisinin araştırılması

Objective: It is suggested that smoking has adverse effects on pla- centa development by decreasing placental vascularization. Cigarette exposure is associated with intrauterine and perinatal death, preterm labor, ablatio placenta, placenta previa and intrauterine growth retardation. The aim of this study is to inves- tigate the effect of smoking on fetal Doppler ultrasound wave- forms and its pathophysiological relationship with fetal birth weight. Methods: The study was conducted in Gynecology and Obstetrics Department of Dokuz Eylul University between January 13th and 24th April 2011. One hundred nineteen single- ton pregnancies were included to the study. Group 1 consisted of 22 patients who were smoking 4-10 cigarettes daily. Group 2 con- sisted of 97 non-smoker patients before and during their pregnan- cies. Patients' maternal uterine, fetal umbilical and fetal middle cerebral arteries Doppler measurements were done on 37th week of gestation. Results: Weight gain in the Group 1 was statistically higher than non-smoking patients. There were statistically significant changes in fetal Doppler measurements, but no difference was found in maternal Doppler waveforms between the two groups. Maternal uterine artery Doppler waveforms were similar in both groups; in fact fetal umbilical artery and middle cerebral artery waveforms were statistically higher for Group 1. Conclusion: Cigarette contains nicotine, carbon monoxide and thousands of other toxic chemicals. Carbon monoxide reduces the oxygen transfer to the fetus. Chronic tobacco use decreases pla- cental blood flow, hypoxic pathologic environment occurs, and changes appear on fetal Doppler ultrasound waveforms.

Comparison of Diagnostic Efficacy of Umbilical Artery and Middle Cerebral Artery Waveform with Color Doppler Study for Detection of Intrauterine Growth Restriction

Intrauterine growth restriction is associated with increased perinatal mortality and morbidity, possibly extending also in adult life, as compared to fetuses and newborns presenting characteristics of normal growth. The present study had been planned to measure the pulsatility index (PI) and resistive index of the middle cerebral artery with pulsatility and resistive index of the umbilical artery in predicting fetal growth restriction. A total of 60 pregnant women with a clinical history and grayscale-screened patients were taken for Doppler analysis, and a final comparison of accuracy of Doppler indices was done with perinatal outcome. The statistical analysis was done using the Statistical Package for Social Sciences version 15.0 statistical analysis software. The values were represented in number (%) and mean±SD. The umbilical artery PI had maximum sensitivity at the third visit (32-37weeks) and maximum specificity also at the third visit (32-37weeks). The umbilical artery resistive index had maximum sensitivity at the second visit (28-32weeks) and maximum specificity at the third visit (32-37weeks). The MCA PI had an overall diagnostic accuracy of 52.8%. The PI of the umbilical artery was more sensitive than the PI of the middle cerebral artery. Umbilical artery PI has the maximum overall diagnostic accuracy of 75%.

The Foetal 'Mind' as a Reflection of its Inner Self: Evidence from Colour Doppler Ultrasound of Foetal MCA.

The unborn healthy foetus is looked upon as a blessing by one and all. A plethora of thoughts arise in the brains of expectant parents. But what goes on in the brain of the yet unborn still remains a mystery. ‘Foetal mind’ is a reflection of functions of its organs of sense, an instrument of knowledge that may even be reduced to machine to demonstrate the effect of sense organs and brain contact. Testimony to this fact are the various waveform patterns obtained non-invasively from the foetal Middle Cerebral Artery (MCA) by using Colour Doppler Ultrasound. Our study, conducted for evaluating the foetal MCA in a rural obstetric population in Maharashtra, India, explains how the MCA - a major artery supplying foetal brain, can give abundant information about foetal heart and foetal stress. When only the foetal heart is stressed by the presence of arrhythmias or ectopic beats, these changes are manifest in the foetal MCA velocity waveform pattern as seen on Colour Doppler study. When the entire foetus is under stress, as in cases of intra uterine growth retardation (IUGR), changes again manifest in the foetal MCA velocity waveform pattern and are designated as the foetal Brain Sparing Effect. Thus scientific evaluation of foetal MCA waveform can objectively demonstrate that the overtly non-communicating foetal brain indeed remains an internal organ of sense and a vital instrument of knowledge to clarify the various effects of sense organs and brain contact. Although the brain parenchyma or cerebral metabolism has not been studied here, cerebral vessels serve as a window to cerebral metabolism, as auto regulatory function of brain leads to changes in haemodynamics of cerebral vessels. Also, like other vessels, MCA mirrors foetal distress and IUGR; but unlike other vessels, e.g. the umbilical or uterine artery, which show these changes in the form of reduction or even reversal of diastolic flow, MCA shows an increase in diastolic component due to brain sparing effect. The unique connection between physical changes in the foetal heart, brain and mental operations are thus critically clarified to some extent, and this helps untangle and comprehend the lattice of mental operations. Although this preliminary study has its limitations, it still carries forward the present corpus of knowledge on the strength of its evidential and critical enquiry and helps unravel the concept of foetal consciousness.

Differences between middle cerebral artery blood velocity waveforms of young and postmenopausal women

We characterized middle cerebral artery (MCA) blood flow velocity waveforms measured by transcranial Doppler ultrasonography in premenopausal (26.6 +/- 6.1 years, mean +/- SD) and postmenopausal (54.0 +/- 3.6 years) women, of whom six were receiving hormone therapy (PM-HT) and seven were not (PM-non-HT). We hypothesized that feature points on MCA waveforms are altered in postmenopausal women compared with those in young women. A short protocol involved maintaining end-tidal PO2 at euoxia (88 mm Hg) and end-tidal PCO2 at 1.5 mm Hg above eucapnic values using a dynamic end-tidal forcing system. Doppler data for the velocity spectral outline (Vp) were collected every 10 ms, and velocity waveform analyses were done on a beat-by-beat basis. Waveform features were identified over each cardiac cycle, including the average Vp (VCYC), maximum acceleration (AMAX), and the ratio of the velocity at the reflected wave and the velocity at peak systole (VR:VMAX). VCYC was unchanged between premenopausal and postmenopausal women (69.4 +/- 9.6 and 67.5 +/- 11.1 cm/s, respectively). AMAX was significantly higher (P = 0.007) in premenopausal women (987.9 +/- 280.7 cm/s) compared with postmenopausal women (743.1 +/- 100.3). Conversely, VR:VMAX was significantly smaller (P < 0.001) in premenopausal women (0.90 +/- 0.09) compared with postmenopausal women (1.11 +/- 0.05). In postmenopausal women, the reflected wave is higher than the maximum velocity at peak systole, suggesting the presence of a shoulder in the MCA waveform. Further investigations are required to assess whether this waveform analysis can provide insight into pathophysiologic changes in cerebral hemodynamics with aging.

The clinical significance of Doppler findings in fetal middle cerebral artery during labor

Objectives: (1) To investigate fetal intracranial circulation, relative to peripheral blood flow, during labor with abnormal cardiotocographic (CTG) patterns, using three non-invasive methods. (2) To determine the utility of monitoring middle cerebral artery (MCA) Doppler during labor. Interventions: Fetuses were assessed using simultaneous CTG, pulse oximetry, and Doppler ultrasonography of both the MCA and umbilical artery (UA) to measure the pulsatility index (PI), resistance index (RI), and flow velocity integral (FVI). Study design: During labor 20 term fetuses with abnormal CTG patterns and oxygen saturation values >30%, and 24 term fetuses with abnormal CTG patterns and oxygen saturation values <30% were studied, and peripartum outcomes were compared. The groups were comparable with regard to maternal age and parity. Results were evaluated using the Student’s t-test and Fisher exact test. Results: MCA Doppler showed significantly lower PI and RI, and higher FVI in the presence of reduced oxygen saturation. Differences in fetal outcomes between the two groups correlated with MCA Doppler findings. Conclusions: In experienced hands, Doppler screening of fetal middle cerebral artery waveforms during labor can be useful in the evaluation of intrapartum hypoxia in complicated pregnancies.

Vascular surgical society of great britain and ireland: transcranial doppler-directed dextran therapy in the prevention of postoperative carotid thrombosis

BACKGROUND: Evidence suggests that embolization precedes carotid thrombosis, a previously unpredictable event complicating 2-3 per cent of all carotid endarterectomies. It was hypothesized that dextran 40 therapy might prevent progression to complete thrombosis in high-risk patients. METHODS: Between October 1995 and July 1998, 400 consecutive patients were monitored following carotid endarterectomy using transcranial Doppler ultrasonography. Those with sustained embolization (more than 25 in 10 min) or those with emboli that distorted the middle cerebral artery waveform were commenced on an incremental dextran 40 infusion. RESULTS: Two hundred and sixteen patients (54 per cent) had one or more emboli detected (96 per cent within 2 h of flow restoration) but only 15 (4 per cent) required dextran therapy. Embolization ceased in each case although the dextran dose had to be adjusted in four. In one of the latter patients, embolization recurred on day 5 but was again controlled with high-dose dextran. Overall, the death and any stroke rate was 2 per cent and no patient suffered a stroke due to carotid thrombosis. CONCLUSION: A few patients develop sustained embolization following carotid endarterectomy which, in previous studies, has been shown to be highly predictive of carotid thrombosis. The authors' experience to date suggests that dextran can stop this phase of embolization and prevent progression to complete carotid thrombosis. However, the dose of dextran has to be adjusted in 25 per cent of patients (i.e. blind administration of dextran may not be effective) and, very rarely, embolization may recur later.

Uterine and fetal cerebral Doppler predict the outcome of third-trimester small-for-gestational age fetuses with normal umbilical artery Doppler.

To assess the value of different admission tests in predicting the outcome of small-for-gestational age (SGA) fetuses with normal Doppler waveforms in the umbilical artery. Criteria for admission into this retrospective study included: singleton pregnancy with a birth weight < 10th centile; absence of severe maternal complications; no evidence of fetal anomalies on the sonogram; normal umbilical artery Doppler; and availability of complete follow-up. At the first antenatal sonogram classifying the fetus as SGA, Doppler analysis of the uterine and middle cerebral arteries was performed and amniotic fluid volume was assessed. Outcome variables included adverse perinatal outcome (perinatal death, severe morbidity) and emergency Cesarean section for fetal distress. Two hundred and thirty-one pregnancies were included in the study. The mean +/- standard deviation birth weight and gestational age at delivery were 2222 +/- 502 g and 37.3 +/- 2.9 weeks, respectively. In 37 cases (16%), an emergency Cesarean section was performed. There was one intrauterine death and three fetuses delivered by emergency Cesarean section developed severe morbidity. Logistic regression demonstrated that abnormal velocimetry of the uterine arteries and fetal middle cerebral artery were independently correlated with the occurrence of Cesarean section. SGA fetuses with normal umbilical artery Doppler waveforms and abnormal uterine arteries and fetal middle cerebral artery waveforms have an increased risk of developing distress and being delivered by emergency Cesarean section. Particularly when both uterine and fetal cerebral waveforms are altered at the same time, the risk is exceedingly high (86%) and delivery as soon as fetal maturity is achieved seems advisable. On the other hand, when both vessels have normal waveforms, the chances of fetal distress are small (4%) and expectant management is the most reasonable choice.

Prevention of postoperative thrombotic stroke after carotid endarterectomy: the role of transcranial Doppler ultrasound.

To determine the incidence of particulate embolization after carotid endarterectomy (CEA), the effect of dextran-40 infusion in patients with sustained postoperative embolization, and the impact of transcranial Doppler (TCD) monitoring plus adjuvant dextran therapy on the rate of postoperative carotid thrombosis. Prospective study in 100 patients who underwent CEA with 6-hour postoperative monitoring using a TCD that was modified to allow automatic, intermittent recording from the ipsilateral middle cerebral artery waveform (10 minute sample every 30 minutes). An incremental dextran-40 infusion was commenced if 25 or more emboli were detected in any 10-minute period. Overall, 48% of patients had one or more emboli detected in the postoperative period, particularly in the first 2 hours. However, sustained embolization that required Dextran therapy developed in only five patients. In each case, the rate of embolization rapidly diminished. A small proportion of patients have sustained embolization after CEA, which in previous studies has been shown to be highly predictive of thrombotic stroke. Intervention with dextran reduced and subsequently stopped all the emboli in those in whom it was used and contributed to a 0% perioperative morbidity and mortality rate in this series.

Doppler ultrasound of the middle cerebral artery: pre-final normalization of cerebrovascular circulation?

We report on the circulatory changes of a severely growth-retarded fetus at 26 weeks of gestation with intrauterine death after 6 days of observation and a birth weight of 480 g. On admission the fetus already showed signs of circulatory centralisation; furthermore, we found pulsation in the umbilical vein and diastolic reverse flow in the umbilical artery. During the days of observation this reverse flow increased and the compensatory phase of fetal circulatory centralisation was followed on the last day by a phase of circulatory decompensation with an apparently normal middle cerebral artery waveform, mimicking preterminal normalisation of fetal cerebral blood flow.

Middle cerebral artery flow velocity waveforms in normal and small-for-gestational-age fetuses

The middle cerebral artery flow velocity waveforms were obtained in 16 normal fetuses in a longitudinal study and in 128 normal fetuses in a cross-sectional study with pulsed Doppler ultrasonography. The pulsatility index values of the middle cerebral artery were higher at 25 to 30 weeks' gestation than those observed during the two periods of major cerebral cellular multiplication in the human fetus. In 9 of the 16 fetuses studied longitudinally we compared the pulsatility index values obtained at the end of gestation with those obtained at 1 month after delivery; no significant difference was observed. The pulsatility index of the middle cerebral artery was also determined in 33 small-for-gestational-age fetuses. A middle cerebral artery pulsatility index value below our normal range was recorded in 9 of the 33 small-for-gestational-age fetuses (27.3%). These small-for-gestational-age fetuses with abnormal pulsatility index values had a significantly higher incidence of abnormal fetal heart rate and admission into the neonatal intensive care unit. There were three deaths in the nine small-for-gestational-age fetuses with abnormal pulsatility index values (33.3%) and three deaths in the 24 small-for-gestational-age fetuses with normal pulsatility index values (12.5%). Our data indicate that the pulsatility index of the middle cerebral artery in the normal human fetus has a parabolic pattern during pregnancy and does not change significantly after delivery. The results suggest that the small-for-gestational-age fetus with a normal middle cerebral artery pulsatility index is at lower risk than the fetus with abnormal pulsatility index values; moreover, management of the small-for-gestational-age fetus may be aided by the study of the middle cerebral artery waveforms.

Middle cerebral artery flow velocity waveforms in normal and small-for-gestational-age fetuses

The middle cerebral artery flow velocity waveforms were obtained in 16 normal fetuses in a longitudinal study and in 128 normal fetuses in a cross-sectional study with pulsed Doppler ultrasonography. The pulsatility index values of the middle cerebral artery were higher at 25 to 30 weeks' gestation than those observed during the two periods of major cerebral cellular multiplication in the human fetus. In 9 of the 16 fetuses studied longitudinally we compared the pulsatility index values obtained at the end of gestation with those obtained at 1 month after delivery; no significant difference was observed. The pulsatility index of the middle cerebral artery was also determined in 33 small-for-gestational-age fetuses. A middle cerebral artery pulsatility index value below our normal range was recorded in 9 of the 33 small-for-gestational-age fetuses (27.3%). These small-for-gestational-age fetuses with abnormal pulsatility index values had a significantly higher incidence of abnormal fetal heart rate and admission into the neonatal intensive care unit. There were three deaths in the nine small-for-gestational-age fetuses with abnormal pulsatility index values (33.3%) and three deaths in the 24 small-for-gestational-age fetuses with normal pulsatility index values (12.5%). Our data indicate that the pulsatility index of the middle cerebral artery in the normal human fetus has a parabolic pattern during pregnancy and does not change significantly after delivery. The results suggest that the small-for-gestational-age fetus with a normal middle cerebral artery pulsatility index is at lower risk than the fetus with abnormal pulsatility index values; moreover, management of the small-for-gestational-age fetus may be aided by the study of the middle cerebral artery waveforms.