Prenatal cardiac biometry and flow assessment in fetuses with bicuspid aortic valve at 20 weeks' gestation: multicenter cohort study.

OBJECTIVE: To investigate prenatal changes in cardiac biometric and flow parameters in fetuses with bicuspid aortic valve (BAV) diagnosed neonatally compared with controls with normal cardiac anatomy. METHODS: This analysis was conducted as part of the Copenhagen Baby Heart Study, a multicenter cohort study of 25 556 neonates that underwent second-trimester anomaly scan at 18 + 0 to 22 + 6 weeks' gestation and neonatal echocardiography within 4 weeks after birth, in Copenhagen University Hospital Herlev, Hvidovre Hospital and Rigshospitalet in greater Copenhagen, between April 2016 and October 2018. From February 2017 (Rigshospitalet) and September 2017 (Herlev and Hvidovre hospitals), the protocol for second-trimester screening of the heart was extended to include evaluation of the four-chamber view, with assessment of flow across the atrioventricular valves, sagittal view of the aortic arch and midumbilical artery and ductus venosus pulsatility indices. All images were evaluated by two investigators, and cardiac biometric and flow parameters were measured and compared between cases with BAV and controls. All cases with neonatal BAV were assessed by a specialist. Maternal characteristics and first- and second-trimester biomarkers were also compared between the two groups. RESULTS: Fifty-five infants with BAV and 8316 controls with normal cardiac anatomy were identified during the study period and assessed using the extended prenatal cardiac imaging protocol. There were three times as many mothers who smoked before pregnancy in the group with BAV as in the control group (9.1% vs 2.7%; P = 0.003). All other baseline characteristics were similar between the two groups. Fetuses with BAV, compared with controls, had a significantly larger diameter of the aorta at the level of the aortic valve (3.1 mm vs 3.0 mm (mean difference, 0.12 mm (95% CI, 0.03-0.21 mm))) and the pulmonary artery at the level of the pulmonary valve (4.1 mm vs 3.9 mm (mean difference, 0.15 mm (95% CI, 0.03-0.28 mm))). Following conversion of the diameter measurements of the aorta and pulmonary artery to Z-scores and Bonferroni correction, the differences between the two groups were no longer statistically significant. Pregnancy-associated plasma protein-A (PAPP-A) multiples of the median (MoM) was significantly lower in the BAV group than in the control group (0.85 vs 1.03; P = 0.04). CONCLUSIONS: Our findings suggest that fetuses with BAV may have a larger aortic diameter at the level of the aortic valve, measured in the left-ventricular-outflow-tract view, and a larger pulmonary artery diameter at the level of the pulmonary valve, measured in the three-vessel view, at 20 weeks' gestation. Moreover, we found an association of maternal smoking and low PAPP-A MoM with BAV. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal aortic distensibility, compliance and pulse pressure assessment during the second half of pregnancy.

The objective of the study was to measure fetal aortic pulse wave velocity and lumen diameter waveforms and subsequently calculate local distensibility, compliance and pulse pressure. A dedicated algorithm for optimizing lumen diameter assessment from radiofrequency ultrasound data is described. Biplane raw data were obtained from a matrix array transducer. We evaluated 83 confirmed, normally developing pregnancies at 22-38 wk. Fetal aortic pulse wave velocity (PWV, m/s) = 0.047 × gestational age (wk) + 1.241, and the distensibility coefficient (1/kPa) = 1/(1.04 × PWV(2)). The logarithm of the local compliance index (mm(2)/kPa) and the pulse pressure (kPa) were both linearly related to gestational age as 0.022 × GA (wk) - 0.343 and 0.012 × GA (wk) + 0.931, respectively. In conclusion, fetal aortic elastic properties can be derived from phase-sensitive radiofrequency data and multiline diameter assessment. Future studies may shed further light on the developmental origins of vascular health and disease.

Assessment of feto-placental well-being in the mare from mid-gestation to term: transrectal and transabdominal ultrasonographic features.

Ultrasound assessment of feto-placental well-being has found its application in the equine field, as a valid diagnostic tool. Most reports on equine fetal parameters focus on advanced to late gestation. The aim of the present study was to further validate the technique of ultrasound evaluation of the equine fetal environment, by extending its application to earlier stages of pregnancy. Fetal parameters were collected (on 150 pregnancies) over a 3-year period. Data included in the study were selected according to the clinical behaviour of the mare, the neonate/fetus and fetal membranes at the termination of gestation. Validation of the ultrasound technique was also undertaken on a number of specimens collected at an abbatoir. At the completion of the study, a substantial number of measurements and observations were collected. No fetal parameters associated in previous reports with a negative outcome were observed at any of the examinations during this study. Therefore, data collected during the present study should be of value in feto-placental assessment of well-being, in mid- to late-gestation.

Assessment of the fetomaternal circulation in threatened abortion by transvaginal color Doppler.

Transvaginal color Doppler was used to investigate blood flow in the fetomaternal circulation of 60 women with threatened abortion and 90 women with normal intrauterine pregnancy. The obtained Doppler sonograms were analyzed and the resistance index (RI) was calculated in the maternal circulation, while in the fetal circulation the pulsatility index (PI) was used. There was no significant difference in the RI values of the maternal circulation between women with normal pregnancies and pregnancies complicated by bleeding, but with normal pregnancy outcome (p > 0.05). No differences in RI values of the uterine, arcuate and radial arteries were found between pregnancies with threatened abortion and normal pregnancy outcome and women with abnormal outcome (p > 0.05). In 9 of 21 women with visible retrochorionic hematoma, the RI of the spiral arteries was higher on the hematoma side in comparison to the opposite side (p < 0.01). This could be a consequence of the mechanical compression caused by the hematoma. In 3 of 4 cases of missed abortion, the RI of the spiral arteries was lower in comparison to the control group. Such findings could be caused by the vasodilatating products of inflammation which probably exist in such areas. There was no significant difference in terms of the PI of fetal blood vessels between normal pregnancy and threatened abortions with normal outcome, as well as between threatened abortions with normal outcome and subsequent abortions of live fetuses (p > 0.05).

Quantitative assessment of circulatory changes in the fetal aortic isthmus during progressive increase of resistance to umbilical blood flow.

BACKGROUND: This study investigated the effects of impairment to placental flow on flow patterns through the aortic isthmus because in the fetus, this vascular segment is the link between the parallel vascular systems perfused by the left and right ventricles. METHODS AND RESULTS: A progressive increase in resistance to blood flow through the placenta was created in seven exteriorized fetal lambs by mechanical umbilical vein compression. Blood flows were measured in the ascending aorta, pulmonary artery, aortic isthmus, and umbilical artery at baseline and at each compression level. The severity of the levels of compression was determined by changes in the flow profile through the umbilical artery. An increase in placental resistance causing a fall in umbilical blood flow of approximately 50% was associated with a retrograde diastolic flow through the aortic isthmus even though the diastolic flow through the umbilical artery remained forward. Because of the systolic predominance, however, the net flow in the isthmus was forward. With a more severe increase in placental resistance corresponding to a decrease of 75% in umbilical blood flow, the net flow through the isthmus approached zero. A strong positive correlation was found between the umbilical blood flow and the net flow through the aortic isthmus (r = .89). CONCLUSIONS: Variations in Doppler blood flow velocity waveforms and integrals of the aortic isthmus can be used as a sensitive indicator of the state of the umbilical circulation.

Two-dimensional and M-mode assessment of aortic growth in the normal and growth-retarded (IUGR) human fetuses.

This study compares human fetal aortic dimensions in 128 normal and 30 intrauterine growth-retarded (IUGR) fetuses using two-dimensional (2D) and M-mode echocardiography. We found that the fetal aortic root in the normally grown fetuses is significantly larger than the descending aorta at all gestational ages. Furthermore, IUGR fetuses had smaller descending aortic dimensions then did normally grown fetuses. When the descending aortic dimension in the IUGR fetuses was corrected for estimated fetal weight, it was found to be of comparable size to those of the normal fetuses. The difference in aortic size of growth-retarded fetuses is proportional to growth and therefore probably a secondary phenomenon.