Altered vascular function in healthy normotensive pregnant women with bilateral uterine artery notches

A Review of Roles of Uterine Artery Doppler in Pregnancy Complications

The invasion of trophoblasts into the uterine decidua and decidual vessels is critical for the formation of placenta. The defects of placentation are related to the etiologies of preeclampsia (PE), fetal growth restriction (FGR), and small-for-gestational age (SGA) neonates. It is possible to predict significant vascular events during pregnancy through uterine artery Doppler (UAD). From the implantation stage to the end of pregnancy, detecting changes in uterine and placental blood vessels can provide a favorable diagnostic instrument for pregnancy complications. This review aims to collect literature about the roles of UAD in pregnancy complications. We consider all relevant articles in English from January 1, 1983 to October 30, 2021. Predicting pregnancy complications in advance allows practitioners to carry out timely interventions to avoid or lessen the harm to mothers and neonates. Administering low-dose aspirin daily before 16 weeks of pregnancy can significantly reduce the incidence of pregnancy complications. From early pregnancy to late pregnancy, UAD can combine with other maternal factors, biochemical indicators, and fetal measurement data to identify high-risk population. The identification of high-risk groups can also lessen maternal mortality. Besides, through moderate risk stratification, stringent monitoring for high-risk pregnant women can be implemented, decreasing the incidence of adversities.

Doppler Indices and Notching Assessment of Uterine Artery Between the 19th and 22nd Week of Pregnancy in the Prediction of Pregnancy Outcome

BACKGROUND/AIM

The aim of this study was to determine the value of Doppler indices and notching assessment of uterine artery between the 19th and 22nd week of gestation in the prediction of pregnancy outcome such as delivery mode, birth weight, Apgar score, afterbirth pH, fetal presentation, preeclampsia and fetal growth restriction in singleton pregnancy.

PATIENTS AND METHODS

This is a retrospective cohort study of Doppler ultrasound of the uterine arteries at 19-22 week of gestation in 1,472 women with singleton pregnancies.

RESULTS

Patients with bilateral high resistance-index (RI) and pulsatility-index (RI) or with the presence of a notch showed a significantly higher prevalence of small for gestational age (SGA) fetuses and intrauterine growth restriction (IUGR), low Apgar Scores at the 1st and the 5th min, high c-section rate, preterm birth, breech birth, placental insufficiency and placental abruption. The presence of a notch significantly increased the prevalence of severe preeclampsia, HELLP-syndrome and oligohydramnios. Also, patients with a bilateral uterine notching had a higher c-section rate along with higher prevalence of SGA and IUGR at screening time.

CONCLUSION

Uterine artery Doppler waveform analysis as well as the assessment of the presence of a notch in the second trimester can be used as a screening method to identify women who will thereafter develop a severe adverse outcome.

Pre-eclampsia: the Potential of GSNO Reductase Inhibitors

PURPOSE OF REVIEW

Pre-eclampsia remains a leading worldwide cause of maternal death and of perinatal morbidity. There remains no definitive treatment except delivery of the fetus.

RECENT FINDINGS

Recent insights into the cardiovascular changes that are evident prior to, during, and persist after pre-eclampsia have improved understanding of the underlying pathophysiology-disruption of normal endothelial function and decreased nitric oxide bioavailability. S-nitrosoglutathione (GSNO) is an endogenous S-nitrosothiol that acts as a NO pool and, by replenishing or preventing the breakdown of GSNO, endothelial dysfunction can be ameliorated. GSNO reductase inhibitors are a novel class of drug that can increase NO bioavailability. GSNO reductase inhibitors have demonstrated improvement of endothelial dysfunction in animal models, and in vivo human studies have shown them to be well tolerated. GSNOR inhibitors offer a potentially promising option for the management of pre-eclampsia.

Cardiovascular function in children born very preterm after intrauterine growth restriction with severely abnormal umbilical artery blood flow

AIMS

Low birthweight has been linked to increased cardiovascular risk in adulthood. We evaluated the effect on cardiovascular outcome of intrauterine growth restriction (IUGR) with abnormal fetal blood flow in children born very preterm.

METHODS

Blood pressure, cardiac function and size, diameters, distensibility, and stiffness of the abdominal aorta, carotid, and popliteal arteries, and endothelial function were assessed non-invasively in 7-year-old children (n = 32) born very preterm with IUGR, with birthweight (median, range) 650 g (395-976 g) and gestational age 27 weeks (24-29 weeks). In addition, intima-media thickness was measured in the carotid artery. Controls were matched for gender and age and had birthweight appropriate-for-gestational-age (AGA). The study included 32 preterm-AGA children with birthweight 1010 g (660-1790) g and 32 term-AGA children with birthweight 3530 g (3000-4390) g.

RESULTS

Preterm-IUGR children had lower microvascular response to acetylcholine, lower aortic stiffness, and higher distensibility compared with the preterm-AGA group (p = 0.019, p = 0.001, and p < 0.001, respectively) and lower carotid intima-media thickness compared with the term-AGA group (p = 0.047). The highest aortic β and lowest distensibility were found in the preterm-AGA group. Height-adjusted systolic blood pressure was higher in the preterm groups than in the term-AGA group (p = 0.018). Cardiac function and size did not differ between the groups.

CONCLUSION

IUGR and preterm birth appear to be associated with structural changes in the arterial wall, whereas preterm birth seems to be associated with higher blood pressure. Using conventional echocardiography, we observed no effect of IUGR on cardiac size and function.

Beyond the placental bed: placental and systemic determinants of the uterine artery Doppler waveform

The uterine artery Doppler waveform has been extensively investigated, though its widespread clinical use as a predictor of adverse pregnancy outcome remains under debate. The determinants of the waveform have classically been ascribed to transformation of the spiral arteries and the development of a low resistance uteroplacental circulation, failure of which predisposes to pre-eclampsia, fetal growth restriction and other adverse outcomes. It has become increasingly evident that although spiral artery transformation determines in some part the characteristics of the Doppler waveform, factors pertaining to maternal vascular and endothelial function are also important.

Should bilateral uterine artery notching be used in the risk assessment for preeclampsia, small-for-gestational-age, and gestational hypertension?

OBJECTIVE

The purpose of this study was to determine the value of bilateral uterine artery notching in the second trimester in the risk assessment for preeclampsia, gestational hypertension, and small-for-gestational-age (SGA) without preeclampsia.

METHODS

This prospective cohort study included 4190 singleton pregnancies that underwent ultrasound examination between 23 and 25 weeks' gestation. The 95th percentiles of the mean pulsatility index (PI) and resistive index (RI) of both uterine arteries were calculated. Multivariable logistic regression analyses were performed to determine if bilateral uterine artery notching is an independent explanatory variable for the occurrence of preeclampsia, early-onset preeclampsia (<or=34 weeks), late-onset preeclampsia (>34 weeks), gestational hypertension, and delivery of an SGA neonate without preeclampsia, while controlling for confounding factors.

RESULTS

(1) The prevalence of preeclampsia, early-onset preeclampsia, late-onset preeclampsia, SGA, and gestational hypertension were 3.4%, 0.5%, 2.9%, 10%, and 7.9%, respectively; (2) 7.2% of the study population had bilateral uterine artery notching; and (3) bilateral uterine artery notching was an independent explanatory variable for the development of preeclampsia (odds ratio [OR], 2.1; 95% confidence interval [CI],1.28-3.36), early-onset preeclampsia (OR, 4.47; 95% CI, 1.50-13.35), and gestational hypertension (OR, 1.50; 95% CI, 1.02-2.26), but not for late-onset preeclampsia or SGA.

CONCLUSIONS

Bilateral uterine notching between 23 and 25 weeks' gestation is an independent risk factor for the development of early-onset preeclampsia and gestational hypertension. Thus, bilateral uterine artery notching should be considered in the assessment of risk for the development of these pregnancy complications.

Changes in Endothelial Function Precede the Clinical Disease in Women in Whom Preeclampsia Develops

Endothelial dysfunction is important in the pathophysiology of preeclampsia. No study has examined endothelial function sequentially at different gestations before development of the clinical syndrome and after delivery (to compare maternal from placental influences). We sought to determine whether endothelial function changes before the clinical development of preeclampsia. We measured skin microvascular function using iontophoresis of acetylcholine and sodium nitroprusside, and laser Doppler imaging at 22, 26, 34 weeks' gestation and 6 weeks postpartum in women identified as being at increased risk of preeclampsia, based on uterine artery Doppler waveforms at 18 to 20 weeks, and controls with normal Doppler waveforms. Fifty-four women remained normotensive and preeclampsia developed in 15. In normotensive and preeclamptic women, acetylcholine responses were augmented during pregnancy compared with postpartum responses (P<0.001). Sodium nitroprusside responses were augmented during pregnancy compared with those postpartum (P<0.005) in preeclamptic women only. Microvascular responses were augmented in women in whom preeclampsia developed, compared with those in normotensive women, at 26 and 34 weeks for acetylcholine (P<0.05 and P<0.001, respectively) and at 22 and 26 weeks for sodium nitroprusside (P<0.05 and P<0.02, respectively). Postpartum acetylcholine and sodium nitroprusside responses were not significantly different between preeclamptic and normal women. Microvascular responses are enhanced during pregnancy in women in whom preeclampsia develops to a level above that seen in normotensive women. These changes precede the onset of clinical disease and might be related to a compensatory increased sensitivity of the microcirculation to nitric oxide.

Impaired vascular growth in late adolescence after intrauterine growth restriction

BACKGROUND

Abnormal blood flow in a fetus small for gestational age indicates true fetal intrauterine growth restriction (IUGR). We tested the hypothesis that IUGR with abnormal fetal blood flow is associated with long-term abnormal vascular morphology and function in adolescence.

METHODS AND RESULTS

In a prospective study, vascular mechanical properties of the common carotid artery (CCA), abdominal aorta, and popliteal artery (PA) were assessed by echo-tracking sonography in 21 adolescents with IUGR and abnormal fetal aortic blood flow and in 23 adolescents with normal fetal growth and normal fetal aortic blood flow. Endothelium-dependent and -independent vasodilatation of the brachial artery was measured by high-resolution ultrasound. After adjustment for body surface area and sex, the IUGR group had significantly smaller end-diastolic vessel diameters than the referents in the abdominal aorta and PA (mean difference, 1.7 mm [95% CI, 0.62 to 2.74] and 0.6 mm [95% CI, 0.25 to 1.02], respectively) (P=0.003 and P=0.002, respectively), with a similar trend in the CCA (P=0.09). A higher resting heart rate was observed in the IUGR group (P=0.01). No differences were found in stiffness or in endothelium-dependent and -independent vasodilatation between the 2 groups.

CONCLUSIONS

IUGR caused by placental insufficiency appears to be associated with impaired vascular growth persisting into young adulthood in both men and women. The smaller aortic dimensions and the higher resting heart rate seen in adolescents with previous IUGR may be of importance for future cardiovascular health.

The popliteal artery, an unusual muscular artery with wall properties similar to the aorta: implications for susceptibility to aneurysm formation?

OBJECTIVE

The popliteal artery is, after the aorta, the most common site for aneurysm formation. Why the popliteal artery is more susceptible than other peripheral muscular arteries is unknown. An important factor may be differences in arterial wall composition as compared with other peripheral muscular arteries, which in turn affect wall properties. These are however unknown. We studied the mechanical wall properties of the popliteal artery in healthy subjects.

MATERIAL AND METHODS

An ultrasound echo-tracking system was used to measure pulsatile changes in popliteal diameter in 108 healthy subjects (56 female, 52 male; age range, 9-82 years). In combination with blood pressure, stiffness (beta), strain, cross-sectional artery wall compliance coefficient (CC), and distensibility coefficient (DC) were calculated. Intima-media thickness (IMT) was registered with a Philips P700 ultrasound scanner.

RESULTS

The popliteal diameter increased with age, and was larger in male subjects than in female subjects (P<.001). Fractional diameter change (strain) decreased with age (P<.001), and strain values were lower in male subjects than in female subjects (P<.01). Accordingly, stiffness increased with age (P<.001), with higher stiffness values in male subjects (P<.01). DC decreased with age (P<.001), with lower DC values in male subjects (P<.01). CC decreased with age, with no difference between genders (P<.001). IMT increased with age (P<.001), with higher IMT values in male subjects (P<.001). The increase in IMT did not affect distensibility.

CONCLUSION

The wall properties of the popliteal artery are affected by age and gender, not only with an increase in diameter, but also with an age-related decrease in distensibility, with male subjects having lower distensibility than in female subjects. This seems not to be the behavior of a true muscular artery, but of a central elastic artery, such as the aorta, and might have implications for susceptibility to arterial dilatation, as well as the association of aneurysm formation between the aorta and the popliteal artery.

CLINICAL RELEVANCE

The popliteal artery is, after the abdominal aorta, the most common location for aneurysm formation in the arterial system. Why it is more susceptible than other arteries is unknown. This study shows that the wall function of the popliteal artery differs from other peripheral arteries, and instead show striking similarities to the abdominal aorta, indicating that the functional arrangement of arterial wall components are similar in the two arteries. This may have implications for the susceptibility to aneurysm formation, as well as the association of dilating disease between the popliteal artery and the abdominal aorta.

Comprehensive assessment of fetal wellbeing: which Doppler tests should be performed?

PURPOSE OF REVIEW

Doppler applications in pregnancy are expanding exponentially. Flow velocity waveforms provide important information 12 weeks to term, from maternal vessels, placental circulation and fetal systemic vessels, with implications for both mother and fetus. As applications proliferate, awareness of the complexity of fetal and placental circulations, in normal pregnancy and in sequential responses to compromise, has also grown. The necessary data are now available to establish core values in Doppler evaluation for at-risk pregnancies.

RECENT FINDINGS

Uterine arteries depict maternal vascular effects of the invading placenta, predicting the frequency and severity of pre-eclampsia and intrauterine growth restriction. New evidence suggests early treatment based on this principle, significantly reduces these impacts. Umbilical artery Doppler reflects downstream placental vascular resistance, strongly correlated with intrauterine growth restriction and the multisystem effects of placental deficiency. Abnormalities are progressive, with reduction, loss, and finally a reversal of diastolic flow. When umbilical arteries become abnormal, the differentiation of fetal status requires Doppler information from systemic vessels. Middle cerebral artery changes begin when the redistribution of cardiac output reflects rising placental resistance, demonstrating 'brain sparing' when cerebrovascular dilation occurs. In the compromised intrauterine growth retarded fetus, precordial veins illustrate fetal cardiac function, changing as the respiratory status declines. This Doppler information is combined with biophysical profile scoring to determine the need for and timing of intervention.

SUMMARY

Doppler evaluation of at-risk pregnancies provides crucial prognostic and diagnostic detail about placentation and fetal adaptation. What has been research detail is now becoming the standard of care, in comprehensive fetal-maternal assessment.