Fetal Internal Carotid Artery Research Articles

Using pentoxifylline, arginine hydrochloride, levocarnitine and rheosorbilact solutions for correction of fetoplacental dysfunction in pregnant women with preeclampsia

Annotation. As of today, there is no effective method for treating the fetoplacental dysfunction (FPD) in pregnant women with preeclampsia. The aim of research was the study of the method proposed by the authors for restoring the functional activity of the fetoplacental complex in pregnant women with FPD on the background of treatment of preeclampsia. А randomized controlled study of the effect proposed treatment (intravenous solution of pentoxifylline; solution containing arginine hydrochloride and levocarnitine; rheosorbilact) of 37 pregnant women at 35-40 weeks of gestation with FPD on the background of moderate preeclampsia, was performed. Such ultrasound doppler measurements have been studied: systolic-diastolic ratio, resistance index, pulsation index in the umbilical arteries, right and left uterine arteries, fetal middle cerebral artery, fetal internal carotid artery and fetal aorta before and after the performed treatment. Statistics were processed using LibreOffice Calc (Mozilla Public License v 2.0), adapted for medical and biological research. We used nonparametric Wilcoxon criteria, Mann-Whitney criteria at a significance level of p <0.05. After the performed treatment, stabilization of the fetoplacental blood circulation in women of the main group was observed, which manifested by decrease in S/D in umbilical artery in 1.3 times, in the left uterine artery in 1.4 times and in the fetal aorta in 1,1 times, and decrease in RI indices in the umbilical artery in 1.1 times, in the right uterine artery in 1.3 times, and increase in the middle cerebral artery in 1.4 times. So, in the course of the proposed treatment, the restoration of the blood flow velocity and the stabilization of vascular resistance in uterine arteries and the umbilical artery were observed in the women of the main group. The research of the possibility of using the above methodology in earlier gestational age and in the risk group for the prevention of preeclampsia is prospective and requires further attention.

Evidence of fetal cerebral vasodilatation induced by submaximal maternal dynamic exercise in human pregnancy.

To investigate the relationship between maternal exercise and fetal circulatory responses in humans during the third trimester of pregnancy, changes in uterine, umbilical and fetal cerebral circulations were measured by pulsed-Doppler ultrasound method in 14 healthy volunteer pregnant women before and just after a moderate non-exhaustive exercise. Maternal heart rate increased significantly reaching 80% of the theoretical maximal heart rate (TMHR) while uterine resistance indices did not change. The fetal heart rate and umbilical mean velocity were unchanged while umbilical resistance index decreased slightly (0.58 +/- 0.06 versus 0.62 +/- 0.07, P < 0.05). The fetal internal carotid artery mean velocity increased (23.2 +/- 5.3 versus 20.4 +/- 4.1 cm/s, P < 0.02) and the cerebral resistance index decreased (0.71 +/- 0.11 versus 0.80 +/- 0.10, P < 0.01). We conclude that submaximal maternal exercise at 80% of TMHR does not significantly alter uterine perfusion but involves a slight fetal cerebral vasodilation which could be due to a moderate fetal hemoglobin desaturation.

Reference ranges and ultrasonographic exposure conditions for pulsed Doppler sonographic studies of the fetal internal carotid artery

We describe the 5th to 95th percentiles for the resistive index from the fetal internal carotid artery and measurements of (1) scanning time and (2) axial distance between transducer face and the fetal skull during pulsed Doppler examinations. Cerebral resistance peaks at 30 weeks' gestation and declines thereafter. The median duration of pulsed Doppler exposure was 31 seconds (range, 4-80 seconds), and the median transducer-skull distance was 2.2 cm (range, 1.3-6.2 cm). Our data provide reference ranges covering the entire period of fetal viability and help define ultrasonographic exposure conditions during pulsed Doppler examinations of fetal intracranial vessels.

Intra-observer and inter-observer reliability of the pulsatility index calculated from pulsed Doppler flow velocity waveforms in three fetal vessels.

Study of the intra observer and inter observer reliability of the pulsatility index, calculated from pulsed Doppler recordings of three fetal vessels. Flow velocity waveforms (FVW) were recorded from the umbilical artery, the fetal descending aorta and the fetal internal carotid artery. Intra-observer reliability was assessed in six fetuses; ten repeated measurements were performed by one observer. Inter-observer reliability was studied in 14 fetuses; two observers performed two repeated measurements in each fetus. A tertiary referral hospital. High risk pregnancies with a gestational age ranging from 29 to 42 weeks. Analysis of variance with repeated measurements and a graphical method were used for data analysis. Intra-observer repeatability was expressed as Intraclass Correlation Coefficient (IntraCC). Inter-observer agreement was expressed as Interclass Correlation Coefficient (InterCC). IntraCC for umbilical artery, descending aorta and internal carotid artery were 0.91, 0.78, and 0.54, respectively. InterCC values for these vessels were 0.39, 0.45 and 0.34, respectively. No systematic differences between the two observers except for the fetal descending aorta, were apparent. IntraCC decreased remarkable when fetuses with absent end diastolic velocities were excluded from the analysis. The pulsatility index (PI) used for fetal measurements has a poor reliability. This is of serious concern when clinical use of FVW measurements is considered as a diagnostic tool.

Placental Transport of Zidovudine in the Rhesus Monkey

Objective: This study was undertaken to characterize the pharmacokinetics of zidovudine (ZDV) and ZDV-glucuronide (ZDVG) in the material and :fetal circulations of the rhesus monkey. Methods: Cannulas were placed in the maternal external jugular and the fetal internal jugular and carotid artery in 8 pregnant monkeys at .120–130 days gestation. ZDV (3.5 mg/kg) was administered to 5 monkeys and ZDVG (3.5 mg/kg) to 3 monkeys as single intravenous bolus infusions through the maternal catheter. Maternal and fetal blood , samples were collected every 20 min for the first 2 h and then every hour for the next 4 h. Maternal and fetal concentrations of ZDV and ZDVG were determined using high, performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Results: In monkeys who received ZDV, the terminal half-life (T1/2) for ZDV was 37±15 and 33 ± 13 min in the maternal and fetal compartments, respectively. The apparent T1/2 for maternal ZDVG was 124 ± 44 and 142 ± 50 min in the maternal and fetal compartments, respectively. Peak levels of ZDV and ZDVG in the fetal compartment were reached 40 min after injection. The mean fetal/maternal concentration ratios for ZDV and ZDVG ranged from 0.20 ± 0.20 at 20 min to a maximum of 0.74 ± 1.0 at 120 min and from 0.28 ± 0.08 at 20 min to 1.4 ± 1.3 at 180 min, respectively. In monkeys who received ZDVG, the T1/2 for ZDWG in the maternal and fetal compartments was 47 ± 26 and 119 ± 164 min, respectively. ZDVG reached its peak in the fetal compartment at 60 min post-injection. The fetal/maternal rafio ranged from 0.08 ± 0.11 at 20 min to 4.2 ± 4.2 at 180 min post-injection. Conclusions: These data demonstrate that 1) ZDV and ZDVG rapidly cross the placenta to the fetal compartment, 2) ZDV crosses more rapidly than ZDVG, and 3) some metabolism of ZDV to ZDVG occurs in the fetal compartment.

Lack of relation between fetal blood gases and fetal blood flow velocity waveform indices found in rhesus isoimmunised pregnancies.

To investigate the relation between umbilical vein blood gas components and the vascular resistance in four fetal arteries in Rh-immunised pregnancies. A prospective observational study over a 4-month period. King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. Fifteen Rh-isoimmunised pregnant women. Pulsed Doppler examinations of the umbilical artery, fetal internal carotid artery, thoracic aorta and abdominal aorta before transabdominal fetal blood sampling from the umbilical vein on 38 occasions. Doppler flow velocity pulsatility index (PI), systolic/diastolic ratio (A/B) and resistance index (RI) in the four fetal arteries investigated were related to the umbilical vein blood gases and acid-base status (PO2, PCO2, O2-content, CO2-content, HCO3, base excess and lactate concentration). There were no correlations between the Doppler indices in any of the vessels studied and the blood gases components in the umbilical vein. The ratios between the corresponding Doppler indices in the different vessels were also independent of the blood gases and acid-base status and there were no significant differences in the Doppler indices in the same vessel between fetuses with blood gas values over the 75th centile and those with values below the 25th centile. This study does not support a reduction in peripheral vascular resistance in the fetal cerebrum in relation to fetal hypoxia in Rh-immunized pregnancies.

Fetal Doppler velocimetry in the internal carotid and umbilical artery during Braxton Hicks' contractions

Using Doppler ultrasound, previous studies revealed a considerable increase in vascular resistance in the uteroplacental circulation during Braxton Hicks' contractions. Consequently, uteroplacental blood flow is reduced and this affects placental oxygen transfer to the fetus, causing a fall in fetal arterial PO 2. In view of the important role of arterial PO 2. In the regulation of cerebral blood flow in the fetus, we hypothesised that Braxton Hicks' contractions cause a decrease in cerebral vascular resistance. A study was undertaken in 16 healthy near term pregnancies, using pulsed-wave Doppler ultrasound to evaluate the influence of Braxton Hicks' contractions on cerebral vascular resistance of the fetus. Flow velocity waveforms (FVWs) were recorded of the fetal internal carotid and umbilical artery and the Pulsatility Index (PI) was calculated. During Braxton Hicks' contractions the PI in the recorded vessels did not change. Fetal heart rate showed also no changes during Braxton Hicks' contractions. These findings indicate that resistance to blood flow downstream of these arteries, is not significantly altered, suggesting that Braxton Hicks' contractions have little or no effect on fetal haemodynamics and on fetal oxygenation in the healthy near term fetus.

Relationship between umbilical and fetal cerebral blood flow velocity waveforms and umbilical venous blood gases.

Nineteen women (mean +/- SD: 28 +/- 5 years) with small fetuses relative to gestational age (mean +/- SD: 32 +/- 2.2 weeks of gestation) were referred to our unit for cordocentesis for the determination of fetal karyotyping. Four of these 19 patients had small-for-gestational-age ultrasound-derived measurements under the third centile for gestational age. Fetal blood gases were measured in the umbilical vein. Umbilical artery and fetal internal carotid artery Doppler examinations were performed 15 min before cordocentesis. The results showed a progressive and proportional increase in umbilical artery resistance index with hypoxia (p < 0.001), hypercapnia (p < 0.025) and acidosis (p < 0.005). Moreover, the results showed a progressive and proportional decrease in fetal internal carotid artery resistance index with hypoxia (p < 0.01), hypercapnia (p < 0.01) and acidosis (p < 0.025). Fetal blood gases are therefore related to umbilical circulatory function and cerebral vasodilatation, suggesting fetal vascular redistribution.

Fetal umbilical and internal carotid artery blood flow velocity waveforms during maternal fenoterol administration

Blood flow velocity waveforms in the fetal umbilical and internal carotid artery were studied during maternal fenoterol treatment in 25 pregnant patients admitted for premature labour between 27 and 35 weeks of gestation. The pulsatility index (PI) from the umbilical artery was significantly reduced (p = 0.02), the PI being situated below the — 2 SD limit of the normal reference curve in 28%. There was no statistically significant difference in PI from the umbilical artery when distinguishing between ruptured and unruptured membranes. The reduced pulsatility index of the umbilical artery suggests a decrease in vascular resistance, hence improved utero-placental perfusion. The pulsatility index of the fetal internal carotid artery followed the normal distribution.

Vibratory acoustic stimulation and the flow velocity waveform in the fetal internal carotid artery

Eleven healthy fetuses between 36 and 39 weeks of gestation were studied during the active sleep state to examine effects of a 5-s vibratory acoustic stimulus on the baseline fetal heart rate and flow velocity waveform in the fetal internal carotid artery. There was an immediate marked rise in baseline fetal heart rate with concomitant drop in pulsatility index in the flow velocity waveform of the fetal internal carotid artery, which persisted for at least 15 min after the stimulus. However, when the pulsatility index was standardized for a fetal heart rate of 140 beats/min this index remained virtually unaltered. These data suggest that in the healthy term fetus during active sleep state, a vibratory acoustic stimulus has no measurable effect on cerebral vascular resistance. Since virtually all reported studies on vibratory acoustic stimulation of the fetus were carried-out during the quiet sleep state, the data from the present study do not provide any information on the safety of this device when employed as a means of assessing of fetal well-being.

Flow velocity waveforms in the fetal internal carotid artery relative to fetal blood gas and acid-base measurements in normal pregnancy

Flow velocity waveforms in the fetal internal carotid artery during fetal behavioural state 2F were compared with blood gas and acid-base data from fetal scalp blood samples immediately following artificial rupture of the membranes in 17 normal term pregnancies. The pulsatility index in the fetal internal carotid artery was positively related to PO 2 and base excess suggesting that also under physiological conditions fetal cerebral vascular resistance may respond to changes in fetal oxygenation.

Prenatal cerebral Doppler ultrasonography and neonatal neurologic outcome.

The significance of fetal cerebral blood flow analysis in the prediction of neonatal neurologic outcome was investigated on 87 fetuses at risk for chronic hypoxia. Blood flow velocity waveforms were recorded from the fetal internal carotid artery immediately before cesarean section; newborns underwent neurologic follow-up until discharged from the neonatal division. Neonatal outcome was considered abnormal in presence of a postasphyxial encephalopathy. Receiver operating characteristic curves were used to demonstrate the efficacy of fetal cerebral blood flow velocity waveform analysis as a predictor of neonatal outcome. A value of the pulsatility index from the internal carotid artery below the second standard deviation of our range of normality was found to be a powerful indicator of the development of neonatal neurologic abnormalities (Cohen's Kappa index = .58). These results were particularly evident in fetuses with a birthweight above 2500 g in which a specificity of 93.7%, a sensitivity of 75%, and an accuracy of 89.7% were achieved.

Vibratory acoustic stimulation and the flow velocity waveform in the fetal internal carotid artery

Eleven healthy fetuses between 36 and 39 weeks of gestation were studied during the active sleep state to examine effects of a 5-s vibratory acoustic stimulus on the baseline fetal heart rate and flow velocity waveform in the fetal internal carotid artery. There was an immediate marked rise in baseline fetal heart rate with concomitant drop in pulsatility index in the flow velocity waveform of the fetal internal carotid artery, which persisted for at least 15 min after the stimulus. However, when the pulsatility index was standardized for a fetal heart rate of 140 beats/min this index remained virtually unaltered. These data suggest that in the healthy term fetus during active sleep state, a vibratory acoustic stimulus has no measurable effect on cerebral vascular resistance. Since virtually all reported studies on vibratory acoustic stimulation of the fetus were carried-out during the quiet sleep state, the data from the present study do not provide any information on the safety of this device when employed as a means of assessing of fetal well-being.

The blood flow velocity waveform in the fetal internal carotid artery in the presence of hydrocephaly

The pulsatility index in the fetal internal carotid artery was studied in the presence of bilateral symmetrical hydrocephaly ( n = 9) and unilateral hydrocephaly ( n = 4). An elevated pulsatility index was demonstrated in five cases (38.5%) suggesting increased resistance to cerebral blood flow. In unilateral hydrocephaly a marked difference in pulsatility index was established between the normal and affected side. No relation could be established between the pulsatility index level and severity of ventriculomegaly or postnatal outcome. Both ventriculomegaly and increased intracranial pressure may play a role in the observed rise in pulsatility index.

Doppler criteria for intrauterine growth retardation: predictive values.

Published data concerning proposed antenatal Doppler criteria for intrauterine growth retardation (IUGR) were critically analyzed using the same technique that has been previously applied to conventional (non-Doppler) sonographic criteria for IUGR. Fifteen studies of Doppler criteria, each conducted in such a way that sensitivity and specificity could be determined, were identified through a literature review. These studies encompassed a variety of arterial waveform and volume blood flow criteria. Bayes' theorem was then used to determine the positive predictive value of each criterion if used as a screening test for IUGR. Criteria involving vessels that have been studied by at least two groups, including those involving umbilical artery waveform, uterine arcuate artery waveform, and umbilical vein volume blood flow, had positive predictive values that fell in a low range (17-57%) similar to that previously found for conventional criteria. Two criteria, using fetal internal carotid artery and thoracic aortic waveforms, had higher positive predictive values (66 and 100%, respectively) in initial studies, but the data have yet to be replicated by other groups. It is concluded that no Doppler criterion has yet been established as a clinically useful method to screen for IUGR antenatally.

Oligohydramnios and fetal cerebral blood flow.

Blood flow velocity waveforms in the fetal internal carotid artery were recorded in five pregnancies complicated by prolonged severe oligohydramnios due to bilateral renal agenesis. End-diastolic flow velocity was reduced, absent or even reversed, resulting in a raised pulsatility index in all five cases. These data suggest that prolonged severe oligohydramnios may hamper cerebral blood flow through fetal head compression.

Fetal internal carotid and umbilical artery blood flow velocity waveforms as a measure of fetal well-being in intrauterine growth retardation.

Maximal flow velocity waveforms were recorded on one occasion from the umbilical artery (UA) and fetal internal carotid artery (ICA) in 240 normal pregnancies and 44 cases of intrauterine growth retardation between 26 and 39 wk of gestation. In normal pregnancy the mean UA pulsatility index (PI) decreased from 1.14 (SD: +/- 0.13) at 26-27 wk of gestation to 0.78 (SD: +/- 0.15) at 38-39 wk. The corresponding decrease in ICA PI was from 1.63 (SD: +/- 0.19) to 1.31 (SD: +/- 0.21). Mean values of UA PI for normal pregnancies were linearly related to gestational age; for ICA PI this relation appeared to be quadratic. Normal limits according to age were constructed by estimated means +/- 2 SD. In intrauterine growth retardation, the UA PI was increased (greater than 2 SD) in 80% of cases, ICA PI was reduced (greater than 2 SD) in only 45%. The outcome of fetuses with intrauterine growth retardation, as expressed by fetal heart rate abnormality, Apgar score at 1 min, and umbilical cord pH, was significantly related to the UA PI but not to the ICA PI.

The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relation to fetal behavioural states in the growth retarded fetus at 37-38 weeks gestation.

In eight women whose fetuses showed evidence of intrauterine growth retardation (IUGR), the relation was examined between the blood flow velocity waveform in the fetal internal carotid and umbilical artery and fetal behavioural states at 37-38 weeks gestation. In both vessels there was a virtual overlap of pulsatility index values originating from state 1F and 2F, reflecting behavioural state independency. In the internal carotid artery this state independency is associated with moderately reduced pulsatility index values.

The Doppler flow velocity waveform in the fetal internal carotid artery with respect to fetal behavioural states. A longitudinal study.

Doppler flow velocity waveforms in the fetal internal carotid artery were recorded in 21 normal pregnancies during fetal behavioural state IF (quiet sleep) and 2F (active sleep) according to Nijhuis and co-workers, from the 36th week of gestation onwards. The present study confirms the earlier finding of a significant reduction of the pulsatility index (PI) in state 2F as compared to state 1F at 37-38 weeks of gestation and demonstrates that this difference in PI exists throughout the entire period, in which fetal behavioural states have been described. Furthermore, it is demonstrated that there is a significant reduction in PI of this vessel during the last 4 weeks of gestation, suggesting a haemodynamic redistribution, favouring blood supply to the brain during the latter weeks of gestation.

Fetal renal anomalies, a diagnostic dilemma in the presence of intrauterine growth retardation and oligohydramnios.

Measurement of the head-to-abdomen (H/A) ratio for differentiating between symmetrical and asymmetrical IUGR may be difficult in the presence of marked oligohydramnios. A total of 76 cases of IUGR with various degrees of oligohydramnios was studied. Sixteen (59%) out of 27 structural defects represented bilateral renal agenesis, 11 of which were diagnosed prenatally. When only the H/A ratio was measured (n = 29) the sensitivity in picking up a structural defect was 50%. Calculation of the pulsatility index in the umbilical artery and fetal internal carotid artery (n = 47), whether or not combined with amnioinfusion (n = 5), resulted in a sensitivity of 76%. It is suggested that the latter two techniques may provide valuable additional information as to the cause of IUGR.