Study of the changes in the position and the pattern of changes of the brain arteries in fetuses and full-term stillborns

We studied cerebral blood vessels in 20 fetuses of the gestation age between 16-36 weeks, and in 5 full-term stillborn cadavers by the method of dissection. One portion of the brain samples were processed by filling the blood vessels with 10% solution of formalin, whereas in the other group we used Mixobar and injected it through carotid artery to demonstrate brain arteries. In early fetal life the arteries are thin and have a straightforward pattern, which is in a direct correlation with the development of the brain. In brain arteries of a 28-week old fetus we observed progressive changes at all three brain arteries that began to assume more curved pattern. Since a significant increase in the brain growth and formation of the gyruses and sulcuses of the brain occurs in the 32nd week, the arteries also assume a wavier pattern, and the number of its branches increases. In full-term stillborns, the arteries are much larger in caliber, they branch abundantly, and due to relatively wide brain sulcuses we may also conclude that their pattern is partially tortuous. From our results it is evident that there are changes in the position, pattern and relationship of brain arteries that are parallel with the brain development and formation gyruses and sulcuses of the brain.

Contribution to the knowledge of position, flow and arterial distribution of cerebral blood vessels in foetuses 4 to 9 months of age

We studied cerebral blood vessels in 25 fetuses of gestational age 16-36 weeks and in 10 cadavers of still-born babies by injection-corrosive method. In the early fetal life, arteries are thin with the straight flow, which is directly connected with the brain development. Progressive changes are observed in all the three cerebral arteries in 28-week old fetus, which straight flow becomes more and more tortuous. As in the 32nd week the brain develops faster and gyri and sulci are being formed, the arteries assume wavy flow and number of their rami increases. In a still-born baby, arteries are of rather bigger caliber; they branch abundantly; and due to their relatively broad cerebral sulci, it can be said that their flow is partly tortuous. Our results show evidently that position, flow and relation of cerebral arteries change concurrently with the brain development and appearance of cerebral gyri and sulci.

Changes in blood vessels in fetuses 4 to 9 months intrauterine life old by postmortem angiography method

We monitored changes in caliber, position and branching of blood vessels in fetuses of 4 - 9 months of intrauterine life. By precise dissection we prepared starting parts of common carotid artery and internal jugular vein in 40 cadaver fetuses. The vessels were injected with Telebrix and subjected to postmortem angiography at the Institute of Radiology Clinics Center in Sarajevo. Thereafter, arteries obtained were compared and analyzed. In preparations of few months old fetal material we observed arteries of fairly straight course, low caliber and with no observable ramification. When preparations of more mature stillborn infants were examined, we detected arteries of undulating course, more expressed ramification and higher caliber. In stillborn babies, all three arteries are of high caliber with rich branching. Considering that in this phase of brain development sulcuses are relatively wide, we can say that course of arteries is partially tortuous. Analysis of venous vessels shows good distinction of venous sinuses and sub-arachnoidal cisterns. We can conclude with great certainty that the changes occur in position, caliber and relationship among vessels in fetus during the period of brain sulci and gyri formation.

3D reconstruction of the cardiovascular and central nervous system of a human embryo Carnegie-stage 15--case report

A human embryo at Carnegie stage 15 was serially sectioned and 3D computer aided reconstructions were made to demonstrate the cardiovascular system and cranial structures and to study developmental variations at this stage. The development of the heart and pharyngeal arteries was according to the existing literature. Differences were found in the development of the arterial circle of Willis and the central nervous system. The cranial venous system seemed to show great variability. Whereas the telencephalon was not developed according to the stage, the development of the hypophysis had occurred prior to stage 15. From the results we conclude that there are remarkable individual differences in embryological differentiation of structures which have to be taken into account during staging of human embryos.

Expression of several cytoskeletal proteins in ovine cerebral arteries: developmental and functional considerations

Cytoskeleton proteins play important roles in regulating vascular smooth muscle (VSM) contraction and relaxation. We tested the hypotheses that the expression levels of several of these proteins change significantly during the course of development, and that these changes contribute to age-related changes in contractile responses. In cerebral arteries from 95-day (d) gestation and 140-d fetus, newborn lambs, and adult sheep, by Western immunoblot (n= 5 for each age) we quantified the relative expression of alpha-actin, alpha-tubulin, cyclophilin A, and proliferating cell nuclear antigen (PCNA). In addition, we examined middle cerebral artery tension responses to phenylephrine (PHE) stimulation in the absence or presence of cytochalasin D (3 x 10(-7)m) and nocodazole (3 x 10(-6)m), inhibitors of alpha-actin and alpha-tubulin polymerization, respectively. The expression levels of alpha-actin and cyclophilin A varied little during the course of development. In contrast, alpha-tubulin expression was approximately 2.5-fold greater in both fetal age groups as compared to adult. Also, as compared to adult and as expected, expression of PCNA was several-fold greater in cerebral arteries of the 95-d fetus (x8), 140-d fetus (x 5), and newborn (x 3). In both adult and fetal middle cerebral artery, cytochalasin D-induced inhibition of actin polymerization decreased PHE-induced contraction, to approximately 60 and approximately 40% of control, respectively (despite no significant change in expression level). In contrast, alpha-tubulin inhibition by nocodazole showed little effect on PHE-induced tension (in spite of the age-related decrease in expression). In conclusion, expression levels of alpha-actin, a thin filament protein involved in contraction, remained relatively constant during the course of development, as did the effects of inhibition of its polymerization on contractility. In contrast, alpha-tubulin, important in intracellular protein trafficking, showed a significant age-related decrease in expression and played a relatively minor role in contractility. The present studies suggest that other cytoskeletal structural proteins and/or elements of pharmaco-mechanical coupling are important to developmental differences in cerebrovascular contractility. In addition, the relatively constant expression levels of alpha-actin and cyclophilin A with development, suggest that these are useful internal standards for studies of cytosolic protein expression.

Fetal cardiac and cerebrovascular acclimatization responses to high altitude, long-term hypoxia

In response to high altitude long-term hypoxemia, the heart of fetal sheep shows a decrease in cardiac output that is secondary to a decrease in myocardial cell contractile function. The intracellular mechanisms responsible for these reductions might include reduced myofibrillar Mg(2+)-activated ATPase. There is also a decrease in beta(1)-adrenergic receptor stimulated augmentation of myocardial contraction. An overproduction of cAMP by beta(1)-adrenergic receptor stimulation, resulting in overphosphorylation of troponin I, may reduce calcium binding by troponin C. Fetal coronary arteries have a reduced contractile response to K(+) depolarization and a reduced sensitivity to a thromboxane A(2) receptor agonist-stimulated contraction. Cerebral arteries of adult sheep (but not the fetus) show decreased responses to both K(+)-depolarization and norepinephrine-induced contraction. Nonetheless, cerebral arteries in the long-term hypoxic fetus demonstrated a number of significant changes from control. For the cerebral arteries in general, high altitude hypoxia is associated with augmented or upregulation of presynaptic functions. In contrast, postsynaptic functions tend to be significantly depressed or downregulated. The results emphasize the role of high altitude, long-term hypoxemia in modulating adrenergic- and serotonergic-mediated signal transduction in the cerebral vasculature. They specifically highlight the significant differences in acclimatization responses between the fetus and adult.

Acute reversible placental dysfunction and abnormal fetal heart rate at delivery

Acute placental dysfunction induced by malaria is characterized by umbilical artery resistance increase and cerebral artery resistance decrease during the crisis. The objective was to evaluate the sensitivity and specificity of fetal Doppler indices and crisis duration for predicting abnormal fetal heart rate (aFHR) at delivery several weeks after the crisis.

METHOD

Every day during the crisis, the umbilical and cerebral resistance indices were measured by Doppler. These indices allowed evaluation of the amplitude of the fetal flow redistribution (C/U = cerebral resistance/umbilical resistance ratio), the duration of the flow redistribution period (i.e. crisis duration) and the Hypoxic index (HI) (mean %C/U change x crisis duration).

RESULTS

POPULATION

46 pregnancies. Mean duration of the flow redistribution period 8+/-3.2 days, mean C/U change -9%+/-6; Hypoxic index -86+/-75; prematures 48%; aFHR 30%). Hypoxic index >150 predicted occurrence of aFHR with high sensitivity and specificity (83%/88%). The presence of abnormal flow distribution (C/U<1.1) and the duration of the period with flow disturbance (>8 days) predicted aFHR at delivery with a sensitivity of 45 and 48% and a specificity of 82 and 84%.

CONCLUSION

The Hypoxic index was more predictive of aFHR at delivery than the amplitude or the duration of the fetal flow redistribution triggered by placental insufficiency.

Chronic hypoxia alters the function of NOS nerves in cerebral arteries of near-term fetal and adult sheep

In addition to adrenergic innervation, cerebral arteries also contain neuronal nitric oxide synthase (nNOS)-expressing nerves that augment adrenergic nerve function. We examined the impact of development and chronic high-altitude hypoxia (3,820 m) on nNOS nerve function in near-term fetal and adult sheep middle cerebral arteries (MCA). Electrical stimulation-evoked release of norepinephrine (NE) was measured with HPLC and electrochemical detection, whereas nitric oxide (NO) release was measured by chemiluminescence. An inhibitor of NO synthase, N(omega)-nitro-l-arginine methyl ester (l-NAME), significantly inhibited stimulation-evoked NE release in MCA from normoxic fetal and adult sheep with no effect in MCA from hypoxic animals. Addition of the NO donor S-nitroso-N-acetyl-dl-penicillamine fully reversed the effect of l-NAME in MCA from normoxic animals with no effect in MCA from hypoxic animals. Electrical stimulation caused a significant increase in NO release in MCA from normoxic animals, an effect that was blocked by the neurotoxin tetrodotoxin, whereas there was no increase in NO release in MCA from hypoxic animals. Relative abundance of nNOS as measured by Western blot analysis was similar in normoxic fetal and adult MCA. However, after hypoxic acclimitization, nNOS levels dramatically declined in both fetal and adult MCA. These data suggest that the function of nNOS nerves declines during chronic high-altitude hypoxia, a functional change that may be related to a decline in nNOS protein levels.

Encephalofacial angiomatosis sparing the occipital lobe and without facial nevus: on the spectrum of Sturge-Weber syndrome variants?

We report two cases of leptomeningeal angiomatosis in atypical frontoparietotemporal locations without an associated facial port-wine stain. Evidence of a leptomeningeal angioma was found in each when they were evaluated for headaches and seizures. The diagnosis of a leptomeningeal angioma was suggested by calcifications noted on computed tomographic scan of the head and confirmed with contrast-enhanced magnetic resonance images of the brain. We hypothesize that given the lack of occipital involvement with the angioma, and therefore the noncontiguous nature of this lesion with the developing upper facial ectoderm, the failure to develop a facial angioma would be expected. We found that the useof an anticonvulsant along with a migraine prophylactic medication appeared to have the greatest efficacy in these two cases, whereas anticonvulsants alone were less helpful. This diagnosis should be considered in any child presenting with seizures or complicated migraines and intracranial calcifications.

Longitudinal measurement of peak systolic velocity in the fetal middle cerebral artery for monitoring pregnancies complicated by red cell alloimmunisation: a prospective multicentre trial with intention-to-treat

OBJECTIVE

To evaluate the utilisation measurements of peak systolic velocities in the middle cerebral artery combined with B-mode ultrasound imaging to predict anaemia in an unselected population of pregnancies complicated by alloimmune antibodies known to cause immunological hydrops.

DESIGN

Prospective study on an intention-to-treat basis.

SETTING

Multicentre study in five large tertiary referral centres.

POPULATION

One hundred twenty-five fetuses with maternal alloantibodies known to cause immunological hydrops.

METHODS

If peak systolic velocity and B-mode scan were reassuring the pregnancy was monitored at 7-14 days interval. If either method showed signs of anaemia, an umbilical fetal blood sampling was performed. When the gestational age was greater than 35 weeks, labour was induced.

MAIN OUTCOME MEASURE

Moderate to severe anaemia at delivery.

RESULTS

Overall sensitivity to detect moderate to severe anaemia below 35 weeks (haemoglobin level below 0.65 multiples of median) was 88%. Specificity was 87%; positive predictive value was 53% and negative predictive value was 98%. The diagnosis of severe anaemia was missed in one fetus; however, the final outcome was good. The method was not useful after 35 weeks.

CONCLUSIONS

Middle cerebral artery peak systolic velocity is a highly sensitive non-invasive means for determining the degree of anaemia present in red blood cell alloimmunised pregnancies. The widespread use of the Doppler method will minimise fetal complications associated with amniocentesis and fetal blood sampling. Non-invasive measurement of middle cerebral artery peak systolic velocities is more convenient and acceptable to alloimmunised pregnancies and may significantly lower health care costs. A Doppler interval of seven days is recommended.

Pre- and postjunctional alpha(2)-adrenergic receptors in fetal and adult ovine cerebral arteries

In ovine cerebral arteries, adrenergic-mediated vasoconstrictor responses differ significantly with developmental age. We tested the hypothesis that, in part, these differences are a consequence of altered alpha(2)-adrenergic receptor (alpha(2)-AR) density and/or affinity. In fetal (approximately 140 days) and adult sheep, we measured alpha(2)-AR density and affinity with the antagonist [(3)H]idazoxan in main branch cerebral arteries and other vessels. We also quantified contractile responses in middle cerebral artery (MCA) to norepinephrine (NE) or phenylephrine in the presence of the alpha(2)-AR antagonists yohimbine and idazoxan and contractile responses to the alpha(2)-AR agonists clonidine and UK-14304. In fetal and adult cerebral artery homogenates, alpha(2)-AR density was 201 +/- 18 and 52 +/- 6 fmol/mg protein, respectively (P < 0.01); however, antagonist affinity values did not differ. In fetal, but not adult, MCA, 10(-7) M yohimbine significantly decreased the pD(2) for NE-induced tension in the presence of 3 x 10(-5) M cocaine, 10(-5) M deoxycorticosterone, and 10(-6) M tetrodotoxin. In fetal, but not adult, MCA, UK-14304 induced a significant decrease in pD(2) for the phenylephrine dose-response relation. In addition, stimulation-evoked fractional NE release was significantly greater in fetal than in adult cerebral arteries. In the presence of 10(-6) M idazoxan to block alpha(2)-AR-mediated inhibition of prejunctional NE release, the fractional NE release was significantly increased in both age groups. We conclude that in fetal and adult ovine cerebral arteries, alpha(2)-AR appear to be chiefly prejunctional. Nonetheless, the fetal cerebral arteries appear to have a significant component of postjunctional alpha(2)-AR.

Fetal hemodynamics

Starting in the left cardiac ventricle the reader is taken on a guided tour on a fetal erythrocyte as measured by Doppler ultrasound. Up in the ascending aorta we move through the aortic isthmus to the descending aorta and the internal umbilical arteries, which fuse around the umbilical cord. With fresh oxygen from the placenta our erythrocyte moves in an accelerating continuous flow along the umbilical vein to the ductus venosus. After having reached the left ventricle again it now passes through a coronary artery to the right atrium and eventually the ductus arteriosus or the pulmonary circulation. Concepts of pulsatility, impedance and resistance are presente in the context of their clinical applicability in Doppler waveforms of various fetal vessels.

Antenatal prediction of intraventricular hemorrhage in fetal growth restriction: what is the role of Doppler?

OBJECTIVE

To evaluate relationships between neonatal intraventricular hemorrhage and altered brain blood flow in preterm growth-restricted fetuses.

METHODS

One hundred and thirteen growth-restricted fetuses (birth weight < 10th centile and umbilical artery pulsatility index > two standard deviations above gestational age mean) which delivered prematurely (< 34.0 weeks) were studied. Three expressions of altered brain blood flow were defined: 'brain sparing'= middle cerebral artery pulsatility index > two standard deviations below the gestational age mean, 'centralization' = ratio of middle cerebral artery/umbilical artery pulsatility indices (cerebroplacental ratio) > two standard deviations below the gestational age mean, and 'redistribution' = absent or reversed umbilical artery end-diastolic velocity. Intraventricular hemorrhage was graded after Papile (I-IV) by cranial ultrasound performed within 7 days of delivery.

RESULTS

Sixty-seven (59.3%) fetuses had brain sparing, 84 (74.3%) had centralization and 51 (45.1%) had redistribution. Fifteen (13.3%) neonates had intraventricular hemorrhage and were more likely to have a biophysical profile < 6, earlier delivery for fetal indications, lower cord artery pH, HCO3, hemoglobin, and platelets, a 10-min Apgar score < 7 and high perinatal mortality (5/15; 33.3%). No associations between intraventricular hemorrhage and brain sparing or centralization were identified. However, neonates with intraventricular hemorrhage had significantly higher umbilical artery pulsatility index deviations from the gestational age mean and a relative risk of 4.9-fold for intraventricular hemorrhage with redistribution (95% confidence interval, 1.5-16.3; P < 0.005). Multiple logistic regression revealed significant associations between intraventricular hemorrhage and a low 10-min Apgar score (r = 0.30, P < 0.005) and low hemoglobin (r = 0.28), gestational age at delivery (r = 0.25) and birth-weight centiles (r = 0.23) (P < 0.05). No Doppler parameter was identified as an independent contributor to intraventricular hemorrhage.

CONCLUSION

While loss of umbilical artery end-diastolic velocity early in gestation significantly increases the risk for neonatal intraventricular hemorrhage, prematurity and difficult transition to extrauterine life remain the most important determinants of intraventricular hemorrhage.

Fetal and adult cerebral artery K(ATP) and K(Ca) channel responses to long-term hypoxia

High-altitude long-term hypoxia (LTH) alters cerebral vascular contractile and relaxation responses in both fetus and adult. We tested the hypotheses that LTH-mediated vascular responses were secondary to altered K+ channel function and that in the fetus these responses differ from those of the adult. In middle cerebral arteries (MCA) from both nonpregnant adult and fetal (approximately 140 days gestation) sheep, which were either acclimatized to high altitude (3,820 m) or sea-level controls, we measured norepinephrine (NE)-induced contractions and intracellular Ca2+ concentration ([Ca2+]i) simultaneously, in the presence or absence of different K+ channel openers or blockers. In adult MCA, LTH was associated with approximately 20% decrease in NE-induced tension and [Ca2+]i, with a significant increase in Ca2+ sensitivity. In contrast, in fetal MCA, LTH failed to affect significantly NE-induced contraction or [Ca2+]i but significantly decreased the ATP-sensitive K+ (K(ATP)) channel and Ca2+-activated K+ (K(Ca)) channel-mediated relaxation. The significant effect of K(ATP) and K(Ca) channel activators on the relaxation responses and the fact that K+ channels play a key role in myogenic tone support the hypotheses that K+ channels play an important role in hypoxia-mediated responses. These results also support the hypothesis of significant developmental differences with maturation from fetus to adult.

[Structural features of the smooth muscle cells in the medial layer of the bifurcation of fetal cerebral arteries]

OBJECTIVE

To study the structural and histogenetic features of the smooth muscle cells (SMCs) in the medial layer of the bifurcation of human cerebral arteries in fetus.

METHOD

Segments of the cerebral arteries from the circle of Willis including the bifurcations of normal human fetuses were sectioned in 1 of the 3 orthogonal planes, wherein the three- dimensional medial layer structure composed of SMCs was observed with light microscope.

RESULT

Microscopic observation identified 1.1 to 9.0 SMC layers in the medial layer of the cerebral arteries from the circle of Willis in the fetuses at different weeks before birth, and 30.3% of the specimens were found to have focal defects of the medial SMC layers at the bifurcation of the developing arteries.

CONCLUSION

The number of SMC layers consisted in the medial layers of the cerebral arteries develops with the fetal growth, and the identification of congenital anomaly of the medial SMCs may help verify the hypothetical pathogenesis for cerebral saccular aneurysms.

L-type Ca2+ channels in fetal and adult ovine cerebral arteries

Recently, we reported that, whereas in cerebral arteries of the adult a majority of norepinephrine (NE)-induced increase in intracellular Ca2+ concentration ([Ca2+]i) comes from release of the sarcoplasmic reticulum (SR) Ca2+ stores, in the fetus the SR Ca2+ stores are relatively small, and NE-induced increase in [Ca2+]i results mainly from activation of plasma membrane L-type Ca2+ channels (20). In an effort to establish further the role of L-type Ca2+ channels in the developing cerebral arteries, we tested the hypothesis that, in the fetus, increased reliance on plasmalemmal L-type Ca2+ channels is mediated, in part, by increased L-type Ca2+ channel density. We used 3H-labeled (+)isopropyl-4-(2,1,3-benzoxadiazol-4-y1)-1,4-dihydro-(2,6-dimethyl-5-methoxycarbonyl)pyridine-3-carboxylate (PN200-110, isradipine) to measure L-type Ca2+ channel density (Bmax) in the cerebral arteries, common carotid artery (CCA), and descending aortae of fetal (approximately 140 gestation days), newborn (7-10 days), and adult sheep. In the cerebral and common carotid arteries, B(max) values (fmol/mg protein) of fetuses and newborns were significantly greater than those of adults. Western immunoblotting assay also revealed that the density of L-type Ca2+ channel protein in the cerebral arteries and CCA was about twofold greater in the fetus than the adult. Finally, compared with the adult, fetal cerebral arteries demonstrated a significantly greater maximum tension and [Ca2+]i in response to stimulation with the L-type Ca2+ channel agonist Bay K 8644. In addition, Bay K 8644-stimulated fetal vessels demonstrated a maximal tension and [Ca2+]i similar to that observed in response to stimulation with 10(-4) NE. These results support the idea that fetal cerebrovascular smooth muscle relies more on extracellular Ca2+ and L-type Ca2+ channels for contraction than does the adult and that this increased reliance is mediated, in part, by greater L-type Ca2+ channel density. This may have important implications in the regulation of cerebral blood flow in the developing organism.

Evidence for abnormal middle cerebral artery values in patients with idiopathic hydramnios

OBJECTIVE

Idiopathic hydramnios is an independent risk factor for perinatal morbidity and mortality, although the precise mechanism is unknown. Hydramnios may alter oxygen delivery to the human fetus. The middle cerebral artery (MCA) pulsatility index (PI) is a sensitive parameter for detection of blood flow redistribution or centralization. The aim of this study was to determine whether idiopathic hydramnios is associated with changes in the PI of the MCA and the umbilical artery (UA).

DESIGN

The PI of the MCA and UA were determined prospectively in 113 consecutive pregnant women with singleton pregnancies and idiopathic hydramnios (study group) and in 113 matched control patients with normal amniotic fluid (AF) volume (control group). The control group was matched for maternal age, gravidity, parity and gestational age at examination. Hydramnios was defined as an AF index above 24 cm. Patients with fetal structural or chromosomal anomalies and with diabetes mellitus were excluded. A PI below the 5th centile for the MCA was considered abnormal.

RESULTS

The rate of abnormal MCA PI was significantly higher in the study group than in the control group (30.9% (35/113) vs. 5.3% (6/113), respectively, OR 8.0; p < 0.0001; 95% CI 3.3-22.1). A significant inverse correlation was found between MCA PI and increasing AF index among patients with hydramnios (p = 0.008, r = 0.46). In contrast, there were no significant differences between the UA PI (0.93 (0.57-2.06) vs. 1.0 (0.49-1.48), (p = 0.20)) and MCA/UA (1.86 (0.77-2.01) vs. 2.15 (0.86-4.11), (p = 0.14)) in both groups.

CONCLUSIONS

Our observations provide evidence of cerebral blood flow redistribution in fetuses with idiopathic hydramnios.

The cerebroplacental Doppler ratio and neonatal outcome in diamnionic monochorionic and dichorionic twins

OBJECTIVE

Neonatal outcome in twins was studied in relation to the cerebroplacental ratio (CPR).

METHODS

Seventy-five infants from twin pregnancies with fetal Doppler data obtained within 3 weeks of delivery were candidates for study (23 infants from diamnionic monochorionic and 52 infants from diamnionic dichorionic twin pregnancies). Multivariate regression analyses were expanded to include 114 twin infants (34 diamnionic monochorionic and 80 diamnionic dichorionic twins). Patients with twin transfusion syndrome were excluded from analysis in the monochorionic group. Targeted ultrasound examination with biometry was performed, and Doppler resistance index (RI) of the umbilical artery (UA) and the middle cerebral artery (MCA) were obtained, and the CPR, a measure of blood flow redistribution, was calculated. Outcome variables included major complications, growth restriction, days of ventilator and oxygen use, days in the neonatal intensive care unit and length of stay.

RESULTS

The CPR was correlated more highly with adverse outcomes such as birth weight, special-care nursery days and length of stay than were the UA RI or the MCA RI. The CPR was significantly lower in monochorionic compared with dichorionic twins (1.12 vs. 1.27, p = 0.01). Multivariate regression analyses conducted separately on each twin group also demonstrated that CPR was superior to UA RI and MCA RI in predicting length of stay and restricted growth. Among the Doppler variables, the CPR showed the highest sensitivity for growth restriction (67%).

CONCLUSION

In twins, CPR was superior to UA RI and MCA RI in predicting adverse neonatal events.

The effect of steroids on the biophysical profile and Doppler indices of umbilical and middle cerebral arteries in healthy preterm fetuses

OBJECTIVE

To examine the effect of antenatal steroids on the biophysical profile and the Doppler parameters of umbilical and middle cerebral arteries of healthy fetuses.

STUDY DESIGN

Thiry-five singleton pregnancies between the gestational ages of 28 and 34 weeks, who received two consecutive doses of betamethasone 24h apart to accelerate pulmonary maturation were prospectively studied. Fetal biophysical profile and Doppler assessment were performed at 0 (pre-steroid), 24, 48, 72, 96 and 120 h after the administration of first dose. We compared the percentage of the fetuses with biophysical parameters present for each of the five components of the biophysical profile and the Doppler indices, using Cochran's Q-test, Friedman's test and one way analysis of variance of repeated measures where appropriate. The statistical significance was defined as P<0.05.

RESULTS

The mean delivery time was 36.9(+/-1.8) weeks. There was a statistically significant difference in the frequency of the following findings in the pre- compared to post-steroid measurements: absence of body movements (48 h, P<0.05), non-reassuring fetal heart rate tracings (24, 48 and 72 h, P<0.05) and absence of breathing movements (24, 48 and 72 h, p<0.05). Initially none of the biophysical profile score was <or=6, whereas at 24, 48 and 72 h, 13.3, 76.7, 16.7% of them, respectively, were <or=6 (P<0.05). None of the Doppler indices was found to be affected by the steroid administration.

CONCLUSION

Maternal betamethasone administration can cause a significant but transient, reduction in biophysical profile scores, however the middle cerebral and umbilical artery Doppler indices were found to be unaffected suggesting the reliability of this modality for the evaluation of the fetuses previously exposed to the antenatal steroids.

The clinical significance of antenatal pathological Doppler findings in the fetal middle cerebral artery in cases with peripheral reduced diastolic doppler flow but no absence of end-diastolic flow in the umbilical artery or fetal aorta

PURPOSE

The effects of antepartum pathological Doppler findings in the fetal middle cerebral artery in cases with simultaneously peripheral reduced diastolic Doppler flow on perinatal outcome and the odds ratio of perinatal risks were studied.

METHODS

214 patients were examined by color Doppler ultrasound in relationship to complications in gestation and labor and fetal outcome. One thousand and seventy Doppler flow measurements of the middle cerebral artery, the umbilical artery and the fetal aorta between 28 and 40 weeks of gestation were performed. Sensitivity and odds ratio of synchronous cerebral pathological and peripheral pathological Doppler blood flow with regard to the prediction of intrauterine growth retardation, rate of cesarean section, preterm delivery and newborn depression was calculated. In all Doppler measurements there were no cases with absence of end-diastolic flow.

RESULTS

Preterm delivery rate and intrauterine growth retardation rate were significantly higher in cases of synchronous cerebral pathological and peripheral pathological Doppler blood flow as in cases of isolated reduced peripheral blood flow (p<0.001; odds ratio 13.2 and 16.6).

CONCLUSION

Pregnancies with no absence of end-diastolic flow in the fetal aorta or umbilical artery, but with reduced diastolic flow in these vessels and simultaneous pathological Doppler findings in the fetal middle cerebral artery are high risk pregnancies, above all in respect to intrauterine growth retardation, preterm delivery and newborn depression. Surveillance of pregnant women should be performed in a perinatal centre.

Ultrasonographic surveillance in red blood cell alloimmunization

OBJECTIVE

This study was undertaken to audit ultrasonographic measurements of fetal liver length and middle cerebral artery peak velocity in cases of red blood cell alloimmunization between 1986 and 1999.

STUDY DESIGN

A total of 200 fetuses at risk for anemia because of red blood cell alloimmunization underwent ultrasonographic measurement of the length of the right lobe of the liver, 45 underwent Doppler recording of middle cerebral artery peak velocity, and 119 underwent fetal blood sampling.

RESULTS

The overall survival was 188 of 200 (94%). Among 69 fetuses found to have anemia, liver length values in 64 (93%) were at the 95th percentile or greater, and the other 5 were in the upper part of the normal range. The middle cerebral artery peak velocity was > or =95th percentile in 15 of the 19 cases of anemia in which this value was measured (79%). Among those measured within 1 week of birth, all liver lengths were at least in the upper part of the normal range, with most >95th percentile, including 1 case with a cord blood hemoglobin concentration <90 g/L.

CONCLUSIONS

All fetuses with anemia identified at fetal blood sampling had enlarged livers with 93% at > or =95th percentile. The peak velocity in the middle cerebral artery was abnormal in most fetuses with anemia.

[Genetic factors related to intracranial arteriovenous malformations]

Genetic studies are interesting not only in the diagnosis and screening of new cases within a family harboring a particular disease, but also in understanding the underlying genetic and molecular factors related to that disease. Such studies revealed 3 categories of cerebral arteriovenous malformations in relationship to possible genetic factors. The first one concerns cerebral arteriovenous malformations in relationship to inherited diseases where a genetic support is clearly identified. Hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease) represents the most classical picture. The second category corresponds to familial cases of cerebral arteriovenous malformations were several members and relatives of the same family harboring the pathology without clear demonstration of any genetic basis. The third category includes cerebral arteriovenous malformations described in association with neurocutaneous disorders issued from maldevelopment events. Sturge-Weber disease and Wyburn-Mason syndrome best illustrate this category. A review of these categories will help in a better understanding of some genetic issues related to cerebral arteriovenous malformations.

Reference ranges and standard percentile-curves for the Doppler indices RI and S/D ratio of the fetal middle cerebral artery. Color Doppler measurements in a perinatal centre

PURPOSE

To perform reference ranges and standard percentile-curves for the Doppler indices resistance index (RI) and systolic/diastolic (S/D) ratio of the fetal middle cerebral artery, periodical color doppler sonographic measurements of 70 pregnant women in the 3rd trimester of pregnancy were done.

METHODS

600 Doppler flow measurements of the fetal middle cerebral artery between 28 and 40 weeks of gestation were performed. The patients had no previous obstetric complications, no apparent medical problems and no complications in pregnancy and labor. Percentiles curves were performed for the RI and the S/D ratio from the 10th percentile up to the 90th percentile.

RESULTS

In the 3rd trimester of pregnancy fetal cerebral circulation shows an increase of the diastolic component and simultaneous decrease in cerebral resistance. The average S/D ratio in week 29 is 8.0, in week 34 6.0 and in the 40th week 3.5. The RI decrement is from 0.88 to 0.67. Other groups demonstrated similar ranges however absolute data are different.

CONCLUSION

The increase in the diastolic component in the middle cerebral artery of the last third of the pregnancy demands reference ranges by using percentile curves. Knowledge of the reference range helps to discriminate between a normal fetal situation and disease. Because of different absolute ranges in the literature each perinatal centre should develop their own data.

The clinical significance of antenatal pathological Doppler findings in fetal middle cerebral artery compared to umbilical artery and fetal aorta

PURPOSE

To compare the diagnostic capacity of fetal Doppler velocimetry in fetal middle cerebral artery to umbilical artery and fetal aorta to the prediction of fetal outcome.

METHODS

229 patients between 28 weeks of gestation (weeks) and 40 weeks were examined by Doppler ultrasound in relationship to complications in gestation and labor, and fetal outcome. One thousand two hundred and seventy doppler blood flow velocity waveforms in the middle cerebral artery, umbilical artery and fetal aorta were recorded. Sensitivity of these vessels with regard to the prediction of intrauterine growth retardation, rate of cesarean section, preterm delivery and new-born depression was calculated. In all Doppler measurements there were no cases with absence of end-diastolic flow.

RESULTS

The differences between pathological fetal outcome were not statistically significant, but diagnostic capacity of the middle cerebral artery velocimetry with regard to the prediction of pathological fetal outcome was on average 11% below the diagnostic capacity of the fetal aorta and umbilical artery.

CONCLUSION

There is no benefit in examining fetal middle cerebral artery Doppler measurements in clinical routine in patients with normal velocity waveforms in the umbilical artery and fetal aorta.