Assessing Early Cardiac Outflow Tract Adaptive Responses Through Combined Experimental-Computational Manipulations

Mechanical forces are essential for proper growth and remodeling of the primitive pharyngeal arch arteries (PAAs) into the great vessels of the heart. Despite general acknowledgement of a hemodynamic-malformation link, the direct correlation between hemodynamics and PAA morphogenesis remains poorly understood. The elusiveness is largely due to difficulty in performing isolated hemodynamic perturbations and quantifying changes in-vivo. Previous in-vivo arch artery occlusion/ablation experiments either did not isolate the effects of hemodynamics, did not analyze the results in a 3D context or did not consider the effects of varying degrees of occlusion. Here, we overcome these limitations by combining minimally invasive occlusion experiments in the avian embryo with 3D anatomical models of development and in-silico testing of experimental phenomenon. We detail morphological and hemodynamic changes 24 hours post vessel occlusion. 3D anatomical models showed that occlusion geometries had more circular cross-sectional areas and more elongated arches than their control counterparts. Computational fluid dynamics revealed a marked change in wall shear stress-morphology trends. Instantaneous (in-silico) occlusion models provided mechanistic insights into the dynamic vessel adaptation process, predicting pressure-area trends for a number of experimental occlusion arches. We follow the propagation of small defects in a single embryo Hamburger Hamilton (HH) Stage 18 embryo to a more serious defect in an HH29 embryo. Results demonstrate that hemodynamic perturbation of the presumptive aortic arch, through varying degrees of vessel occlusion, overrides natural growth mechanisms and prevents it from becoming the dominant arch of the aorta.

Prenatal diagnosis of aortic arch anomalies: Echocardiography, 3D-ultrasonography, and computed tomography angiogram findings. A case-report

We report the case of a fetus presenting aortic arch anomalies associated with a ventricular septal defect (VSD). This fetus, which was referred at 25 weeks of gestation, was suspected to have coarctation of aorta (CoA) evidenced by enlarged right chambers at the four-chamber view during a routine obstetric ultrasonographic scan. The prenatal diagnosis of CoA remains a challenge. Here, we review the ultrasonographic findings that could contribute to this diagnosis.

Cell-Extracellular Matrix Interactions Play Multiple Essential Roles in Aortic Arch Development

RATIONALE

Defects in the morphogenesis of the fourth pharyngeal arch arteries (PAAs) give rise to lethal birth defects. Understanding genes and mechanisms regulating PAA formation will provide important insights into the etiology and treatments for congenital heart disease.

OBJECTIVE

Cell-ECM (extracellular matrix) interactions play essential roles in the morphogenesis of PAAs and their derivatives, the aortic arch artery and its major branches; however, their specific functions are not well-understood. Previously, we demonstrated that integrin α5β1 and Fn1 (fibronectin) expressed in the Isl1 lineages regulate PAA formation. The objective of the current studies was to investigate cellular mechanisms by which integrin α5β1 and Fn1 regulate aortic arch artery morphogenesis.

METHODS AND RESULTS

Using temporal lineage tracing, whole-mount confocal imaging, and quantitative analysis of the second heart field (SHF) and endothelial cell (EC) dynamics, we show that the majority of PAA EC progenitors arise by E7.5 in the SHF and contribute to pharyngeal arch endothelium between E7.5 and E9.5. Consequently, SHF-derived ECs in the pharyngeal arches form a plexus of small blood vessels, which remodels into the PAAs by 35 somites. The remodeling of the vascular plexus is orchestrated by signals dependent on the pharyngeal ECM microenvironment, extrinsic to the endothelium. Conditional ablation of integrin α5β1 or Fn1 in the Isl1 lineages showed that signaling by the ECM regulates aortic arch artery morphogenesis at multiple steps: (1) accumulation of SHF-derived ECs in the pharyngeal arches, (2) remodeling of the EC plexus in the fourth arches into the PAAs, and (3) differentiation of neural crest-derived cells adjacent to the PAA endothelium into vascular smooth muscle cells.

CONCLUSIONS

PAA formation is a multistep process entailing dynamic contribution of SHF-derived ECs to pharyngeal arches, the remodeling of endothelial plexus into the PAAs, and the remodeling of the PAAs into the aortic arch artery and its major branches. Cell-ECM interactions regulated by integrin α5β1 and Fn1 play essential roles at each of these developmental stages.

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta

OBJECTIVES

Prenatal diagnosis of coarctation of the aorta (CoA) is associated with reduced mortality and morbidity, however, accurate prenatal prediction remains challenging. To date, studies have used retrospective measurements of the outflow tracts to evaluate their potential to predict CoA. Our primary objective was to evaluate prospectively acquired measurements of the outflow tracts in fetuses with prenatally suspected CoA. A secondary aim was to report the postnatal prevalence of bicuspid aortic valve in this cohort.

METHODS

Pregnancies with suspicion of isolated CoA and with a minimum of 6 months' postnatal follow-up available were identified from the cardiac database of a tertiary fetal cardiology center in the UK, between January 2002 and December 2017. Measurement of the aortic valve, pulmonary valve, distal transverse aortic arch (DTAA) and arterial duct (AD) diameters were undertaken routinely in fetuses with suspected CoA during the study period. Z-scores were computed using published reference ranges based on > 7000 fetuses from our own unit.

RESULTS

Of 149 pregnancies with prenatally suspected CoA included in the study, CoA was confirmed within 6 months after birth in 77/149 (51.7%) cases. DTAA diameter Z-score and the Z-score of second-trimester DTAA/AD diameter ratio were smaller in fetuses with postnatally confirmed CoA than those in false-positive cases (-2.8 vs -1.9; P = 0.039 and -3.13 vs -2.61; P = 0.005, respectively). Multiple regression analysis demonstrated that the Z-scores of DTAA and AD diameters were the only significant predictors of postnatal CoA (P = 0.001). Bicuspid aortic valve was identified in 30% of the false-positive cases.

CONCLUSIONS

Measurement of DTAA and AD diameter Z-scores can be used to ascertain risk for postnatal CoA in a selected cohort. The high incidence of bicuspid aortic valve in false-positive cases merits further study with respect to both etiology and longer-term significance. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Pbx4 limits heart size and fosters arch artery formation by partitioning second heart field progenitors and restricting proliferation

Vertebrate heart development requires the integration of temporally distinct differentiating progenitors. However, few signals are understood that restrict the size of the later-differentiating outflow tract (OFT). We show that improper specification and proliferation of second heart field (SHF) progenitors in zebrafish lazarus (lzr) mutants, which lack the transcription factor Pbx4, produces enlarged hearts owing to an increase in ventricular and smooth muscle cells. Specifically, Pbx4 initially promotes the partitioning of the SHF into anterior progenitors, which contribute to the OFT, and adjacent endothelial cell progenitors, which contribute to posterior pharyngeal arches. Subsequently, Pbx4 limits SHF progenitor (SHFP) proliferation. Single cell RNA sequencing of nkx2.5+ cells revealed previously unappreciated distinct differentiation states and progenitor subpopulations that normally reside within the SHF and arterial pole of the heart. Specifically, the transcriptional profiles of Pbx4-deficient nkx2.5+ SHFPs are less distinct and display characteristics of normally discrete proliferative progenitor and anterior, differentiated cardiomyocyte populations. Therefore, our data indicate that the generation of proper OFT size and arch arteries requires Pbx-dependent stratification of unique differentiation states to facilitate both homeotic-like transformations and limit progenitor production within the SHF.

Effect of Gestational Age on Maternofetal Vascular Function Following Single Maternal Engineered Nanoparticle Exposure

Normal pregnancy outcome is accomplished, in part, by rapid and expansive physiological adaptations to the systemic circulation, the extent of which is specific to gestational day (GD) and anatomical location. Pregnancy-related hemodynamic changes in uterine placental blood flow stimulate compensatory vascular signaling and remodeling that begins early and continues throughout gestation. Exposure of the maternal environment to engineered nanomaterials (ENM) during pregnancy has been shown to impact health of the dam, fetus, and adult offspring; however, the consequences of specific temporal (gestational age) and spatial (vascular location) considerations are largely undetermined. We exposed pregnant Sprague-Dawley rats to nano-TiO2 aerosols at three critical periods of fetal development (GD 4, 12, and 17) to identify vascular perturbations associated with ENM exposure at these developmental milestones. Vascular reactivity of the maternal thoracic aorta, the uterine artery, the umbilical vein, and the fetal thoracic aorta were evaluated using wire myography on GD 20. While impairments were noted at each level of the maternofetal vascular tree and at each exposure day, our results indicate the greatest effects may be identified within the fetal vasculature (umbilical vein and fetal aorta), wherein effects of a single maternal inhalational exposure to nano-TiO2 on GD 4 modified responses to cholinergic, NO, and α-adrenergic signaling.

An In-depth Perspective of Aortic Arch Branching in Fetal Vascular Rings Using Spatiotemporal Image Correlation Combined With High-definition Flow Imaging: Report of 4 Cases

On the basis of 2-dimensional fetal echocardiographic findings, we investigated 4 different fetal vascular ring cases using spatiotemporal image correlation (STIC) combined with high-definition (HD) flow imaging. An in-depth 3-dimensional perspective of aortic arch branching (ie, the brachiocephalic arteries) was created by application of glass body and HDlive flow rendering algorithms (GE Healthcare, Zipf, Austria). Additionally, complete (U- or O-shaped) or incomplete (C-shaped) vascular rings were clearly differentiated in utero, and articulations around the trachea and esophagus were more easily imaged. In conclusion, spatiotemporal image correlation combined with HD flow imaging could classify fetal vascular rings with accuracy and facilitate decision making during postnatal management.

Strategies for Accurate Diagnosis of Fetal Aortic Arch Anomalies: Benefits of Three-Dimensional Sonography With Spatiotemporal Image Correlation and a Novel Algorithm for Volume Analysis

BACKGROUND

Obtaining an accurate diagnosis of fetal aortic arch anomalies is often difficult with traditional two-dimensional (2D) sonography. Thus, the aim of this study was to assess the value of three-dimensional (3D) sonography with spatiotemporal image correlation for diagnosing fetal aortic arch anomalies using a novel algorithm for 3D volume analysis.

METHODS

Two-dimensional and 3D echocardiographic image data from 300 normal fetuses and 30 fetuses with aortic arch anomalies were retrospectively reviewed. Grayscale and high-definition flow imaging data were available for 2D echocardiography. Three-dimensional volumes were acquired in parasagittal views with high-definition flow imaging information. Volume postprocessing was performed using a novel algorithm to obtain 3D tomographic ultrasound imaging slices and color-rendered images. Detection of aortic arch positions, aberrant brachiocephalic patterns, and aortic arch anomalies was compared for 2D and 3D modalities. Postnatal echocardiography was used as the truth standard in assessing aortic anatomy.

RESULTS

In total, four cases of double aortic arch, 21 cases of right aortic arch, one case of retroesophageal aortic arch, and four cases of left aortic arch with aberrant right subclavian arteries were included. Inter- and intraobserver agreement were excellent for 2D and 3D modalities. The 3D modality offered better sensitivity and accuracy compared with 2D imaging for the detection of brachiocephalic anomalies (P < .01) and arch anomalies (P < .01) but comparable sensitivity for arch position. There was no difference in specificity for both modalities.

CONCLUSIONS

The proposed novel algorithm for volume postprocessing ensures that 3D reconstructed images are obtained with high repeatability. The addition of 3D spatiotemporal image correlation to fetal echocardiography may offer a more accurate diagnosis for arch anomalies.

"Y Sign" at the Level of the 3-Vessel and Trachea View: An Effective Fetal Marker of Aortic Dextroposition Anomalies in the First Trimester

OBJECTIVES

The "Y sign" at the level of the 3-vessel and trachea view corresponds to thinning of main pulmonary artery and arterial duct and a dilated transverse aortic arch. The purpose of this study was to evaluate the Y sign for the diagnosis of aortic dextroposition anomalies at the time of the first-trimester scan and to assess the screening performance of only the Y sign, only abnormal left axis deviation (axis sign), and their combination for the diagnosis of aortic dextroposition anomalies.

METHODS

A prospective evaluation of 6025 pregnant women undergoing first-trimester ultrasonography was conducted. The cardiac axis was measured in all examined patients and considered abnormal (positive axis sign) at greater than 57 °. The frequency of the Y sign and the axis sign was assessed for this population, and their screening performance for the diagnosis of aortic dextroposition anomalies was calculated.

RESULTS

A total of 5775 patients fulfilled the inclusion criteria. Aortic dextroposition anomalies were diagnosed in 17 cases (tetralogy of Fallot in 8 and Fallot-like double-outlet right ventricle in 9). The Y sign was found in 18 of 5775 (0.3%) fetuses examined, of which 7 of 18 were confirmed with tetralogy of Fallot, 9 of 18 with a Fallot-like double-outlet right ventricle, and 2 of 18 with pulmonary stenosis. A positive axis sign of greater than 57 ° was found in 20 fetuses, including 4 with normal heart anatomy. The sensitivity values of the Y sign, the axis sign, and their combination were 94%, 76%, and 94%, respectively.

CONCLUSIONS

Visualization of the Y sign should increase the suspicion of aortic dextroposition anomalies in the late first trimester. The screening performance of the Y sign alone and in combination with an abnormal cardiac axis was high and may aid in the early diagnosis of aortic dextroposition anomalies in the fetus.

Aberrant Right Vertebral Artery with a Diverticulum of Kommerell: Review of a Rare Aortic Arch Anomaly

The normal aortic arch branching pattern is of a three-vessel arch with the vertebral arteries arising from the subclavian arteries. There are a variety of well-known symptomatic and asymptomatic aortic branching patterns widely reported in the literature. An anomalous right vertebral artery with a diverticulum of Kommerell is an extremely rare variant, with few other cases reported in the literature. Herein, we review the embryology of the aortic arch and vertebral artery, the various types of Kommerell's diverticula and the clinical significance of this anomaly.

Fetal aortopulmonary window: case series and review of the literature

Aortopulmonary window is a rare congenital cardiac anomaly characterized by communication between the aorta and the pulmonary artery above the semilunar valves. Prenatal diagnosis is rare. We report four fetuses with aortopulmonary window and review the relevant literature. Approximately half of the reported cases had additional cardiac defects. None had chromosomal abnormalities. In cases with normal cardiac connections, the diagnosis can be made prenatally on the standard three-vessel view, as seen in two of our cases. In one fetus with complete transposition of the great arteries, the diagnosis was made retrospectively on sagittal views. In the remaining case, the window was seen postnatally but could not be identified retrospectively due to the abnormal superoinferior relationship of the ventricles and vessels. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Identification and management of fetal isolated right-sided aortic arch in an unselected population

OBJECTIVE

Inclusion of the three vessels and trachea view in the routine assessment of the fetal heart at the 18-20-week morphology scan improves recognition of a right-sided aortic arch (RAA). We report our experience of RAA diagnosed in an unselected population of pregnant women attending for a routine morphology scan.

METHODS

The obstetric imaging databases of two ultrasound centers were reviewed retrospectively to identify all routine fetal morphology scans performed at 18-22 weeks' gestation between January 2011 and December 2014. A review of postnatal charts was conducted to ascertain findings at birth, neonatal complications and the anatomical findings at any neonatal echocardiographic or surgical procedure. Parents of older infants were contacted by phone to assess their wellbeing and identify any respiratory or feeding difficulties.

RESULTS

In the 48-month study period, 43 083 routine anomaly scans were performed. Twenty-three cases of isolated RAA were identified, a prevalence of 0.05%. Nineteen (83%) cases of isolated RAA had a left-sided arterial duct and four (17%) had a right-sided duct. Postnatal follow-up data were obtained in all cases. The prevalence of a symptomatic vascular ring due to a double aortic arch was 13% (3/23). One (4%) case was diagnosed with DiGeorge syndrome.

CONCLUSIONS

RAA can be identified easily on a routine fetal anomaly scan, however the prevalence of RAA is low in an unselected population. Antenatally diagnosed cases should be referred for detailed fetal echocardiography and the patient should be made aware of the association with DiGeorge syndrome and the symptoms associated with a vascular ring. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal Diagnosis of an Aortopulmonary Window With an Interrupted Aortic Arch

A prenatal aortopulmonary window with an interrupted aortic arch was detected in a 22-week-old fetus. The 3-vessel and trachea view showed a communication between the ascending aorta and the pulmonary artery. Early postnatal surgery was successful. A PubMed-based search identified all cases of prenatal aortopulmonary windows between 2002 and 2015. Nine articles were identified. The average gestational age at diagnosis was 28 weeks (range, 22-33 weeks). The most frequent aortopulmonary window was type I (40%). All cases were associated with congenital heart defects, mainly an interrupted aortic arch (50%). No chromosomal or extracardiac abnormalities were seen. Prenatal echocardiography is useful for early diagnosis of an aortopulmonary window. The prognosis depends on the time of surgery and the nature of the associated anomalies.

Fetuses with right aortic arch: a multicenter cohort study and meta-analysis

OBJECTIVES

Use of recent antenatal screening guidelines for cardiac abnormalities has increased fetal diagnoses of right aortic arch (RAA). We aimed to establish the outcome of fetal RAA without intracardiac abnormalities (ICA) to guide postnatal management.

METHODS

In the retrospective cohort part of our study, outcome measures were rates of chromosomal abnormalities, 22q11.2 deletion, fetal extracardiac abnormalities (ECA), postnatal ICA and ECA, and symptoms of and surgery for vascular ring. A systematic review and meta-analysis was also performed; results are reported as proportions. Kaplan-Meier analysis of vascular ring cases with surgery as endpoint was performed.

RESULTS

Our cohort included 86 cases; 41 had a vascular ring. Rates of chromosomal abnormalities, 22q11.2 deletion and fetal ECA were 14.1%, 6.4% and 17.4%, respectively. Sixteen studies including our cohort (312 fetuses) were included in the systematic review. Overall rates of chromosomal abnormalities and 22q11.2 deletion were 9.0% (95% CI, 6.0-12.5%) and 6.1% (95% CI, 3.6-9.3%), whilst the respective rates for cases with no ECA were 4.6% (95% CI, 2.3-7.8%) and 5.1% (95% CI, 2.4-8.6%). ECA were seen in 14.6% (95% CI, 10.6-19.0%) prenatally and in 4.0% (95% CI, 1.5-7.6%) after birth. Postnatal ICA were identified in 5.0% (95% CI, 2.7-7.9%). Rate of symptoms of vascular rings (follow-up ≥ 24 months postpartum) was 25.2% (95% CI, 16.6-35.0%), and 17.1% (95% CI, 9.9-25.7%) had surgery. Two-year freedom from surgery was 83.0% (95% CI, 74.3-90.1%).

CONCLUSIONS

Fetal RAA without ICA is more frequently associated with ECA than with chromosomal abnormalities. Most cases, however, are isolated. Vascular-ring symptoms occur in about 25% of cases. Postnatal surveillance is required mainly in the first 2 years after delivery.

Assessment of cardiac angle in fetuses with congenital heart disease at risk of 22q11.2 deletion

OBJECTIVES

To evaluate fetal cardiac angle as a screening tool for 22q11.2 deletion among cases with cardiac anomalies known to be associated with this genetic condition, to examine the correlation of fetal cardiac angle with thymic-thoracic (TT)-ratio, and to assess the performance of TT ratio as a covariate in screening for 22q11.2 deletion.

METHODS

This was a retrospective cohort study that reviewed the records of 74 cases with cardiac anomalies known to be associated with 22q11.2 deletion (tetralogy of Fallot, common arterial trunk, interrupted aortic arch and right aortic arch) that were diagnosed between 2007 and 2013. The karyotype was known in all cases. The fetal cardiac angle and TT-ratio were measured using stored three-dimensional spatiotemporal image correlation volume datasets and compared in those with del.22q11.2 and those without.

RESULTS

Of the 74 cases reviewed, 16 had 22q11.2 deletion. The mean cardiac angle was larger in the cases with 22q11.2 deletion than in those without (68.6° vs 58.7°, respectively; P = 0.02). Multivariate regression analysis showed an association between cardiac angle and TT-ratio in fetuses with 22q11.2 deletion (r(2)  = 0.33; P = 0.02) but not in those with a normal karyotype (P = 0.4). Logistic regression analysis demonstrated that fetal cardiac angle, but not TT-ratio, is an independent predictor of 22q11.2 deletion among fetuses with 22q11.2 deletion-associated cardiac anomalies (P = 0.02; area under the receiver-operating characteristics curve = 0.69).

CONCLUSIONS

An enlarged fetal cardiac angle is an independent predictor of 22q11.2 deletion among fetuses with 22q11.2 deletion-associated cardiac anomalies. However, its performance as a single variable in a screening model is not sufficient to guide management decisions regarding invasive testing.

Prenatal Sonographic Features of a Double Aortic Arch: Literature Review and Perinatal Management

A double aortic arch is a relatively uncommon anomaly occasionally associated with congenital heart disease or the chromosome 22q11 deletion. We report a case of prenatal diagnosis of a double aortic arch in which the sonographic features in the 3-vessel and trachea view are highlighted. A PubMed-based search was made to retrieve all cases of prenatal diagnosis of double aortic arch. A total of 13 articles and 35 cases were found. The average gestational age at diagnosis was 29 weeks. Six cases had associated cardiac anomalies. Only 1 case had the 22q11 deletion, showing extracardiac anomalies without cardiac defect. The postnatal evolution was characterized by symptoms of tracheoesophageal compression in 72.4% of the cases. Detection of a double aortic arch should be followed by a thorough fetal scan and echocardiography, and a chromosomal study should be considered when the sonographic findings are consistent with the 22q11 deletion.

Growth and hemodynamics after early embryonic aortic arch occlusion

The majority of severe clinically significant forms of congenital heart disease (CHD) are associated with great artery lesions, including hypoplastic, double, right or interrupted aortic arch morphologies. While fetal and neonatal interventions are advancing, their potential ability to restore cardiac function, optimal timing, location, and intensity required for intervention remain largely unknown. Here, we combine computational fluid dynamics (CFD) simulations with in vivo experiments to test how individual pharyngeal arch artery hemodynamics alter as a result of local interventions obstructing individual arch artery flow. Simulated isolated occlusions within each pharyngeal arch artery were created with image-derived three-dimensional (3D) reconstructions of normal chick pharyngeal arch anatomy at Hamburger-Hamilton (HH) developmental stages HH18 and HH24. Acute flow redistributions were then computed using in vivo measured subject-specific aortic sinus inflow velocity profiles. A kinematic vascular growth-rendering algorithm was then developed and implemented to test the role of changing local wall shear stress patterns in downstream 3D morphogenesis of arch arteries. CFD simulations predicted that altered pressure gradients and flow redistributions were most sensitive to occlusion of the IVth arches. To evaluate these simulations experimentally, a novel in vivo experimental model of pharyngeal arch occlusion was developed and implemented using two-photon microscopy-guided femtosecond laser-based photodisruption surgery. The right IVth arch was occluded at HH18, and resulting diameter changes were followed for up to 24 h. Pharyngeal arch diameter responses to acute hemodynamic changes were predicted qualitatively but poorly quantitatively. Chronic growth and adaptation to hemodynamic changes, however, were predicted in a subset of arches. Our findings suggest that this complex biodynamic process is governed through more complex forms of mechanobiological vascular growth rules. Other factors in addition to wall shear stress or more complex WSS rules are likely important in the long-term arterial growth and patterning. Combination in silico/experimental platforms are essential for accelerating our understanding and prediction of consequences from embryonic/fetal cardiovascular occlusions and lay the foundation for noninvasive methods to guide CHD diagnosis and fetal intervention.

'Post-LA space index' as a potential novel marker for the prenatal diagnosis of isolated total anomalous pulmonary venous connection

OBJECTIVES

To review the fetal echocardiograms of patients with total anomalous pulmonary venous connection (TAPVC) in order to determine whether the distance between the left atrium and the descending aorta would be useful in the prenatal diagnosis of fetal TAPVC.

METHODS

We reviewed the fetal echocardiograms of eight cases of TAPVC (five supracardiac type and three infracardiac type) with no other cardiac malformations. We evaluated the ratio of the left atrium-descending aorta distance to the diameter of the descending aorta ('post-LA space index') in 101 normal and eight TAPVC fetuses, and compared the values between groups. In addition, we examined the tricuspid valve/mitral valve diameter ratio (TVD/MVD) and the right ventricular end-diastolic diameter/left ventricular end-diastolic diameter ratio (RVDd/LVDd).

RESULTS

The echocardiograms for fetuses with TAPVC and normal fetuses were performed at mean gestational ages of 27.5 weeks and 29.6 weeks, respectively. There were no significant differences in the TVD/MVD and RVDd/LVDd ratios between the groups. However, the post-LA space index was significantly higher in the TAPVC cases (mean, 1.51) than it was in the normal fetuses (mean, 0.71 ± 0.23) (P < 0.0001). On an analysis of the receiver-operating characteristics curve, a post-LA space index cut-off of 1.27 was found to be optimal for distinguishing between TAPVC and normal hearts, with a sensitivity of 100% and specificity of 99%.

CONCLUSIONS

The novel post-LA space index could potentially be used for the prenatal diagnosis of TAPVC. A diagnosis of TAPVC is very likely in cases with a post-LA space index of > 1.27.

Profiling left and right ventricular proportional output during fetal life with a novel systolic index in the aortic isthmus

OBJECTIVE

Left ventricular ejection causes forward flow in the fetal aortic isthmus while the right ventricle has a retrograde influence. The aim of this study was to create reference values for an isthmic systolic index (ISI) reflecting the changing influence of right and left ventricular performance on Doppler flow velocity waveforms of the aortic isthmus throughout normal pregnancy.

METHODS

Doppler recordings of 260 normal fetuses with a gestational age of 18-37 weeks were reviewed. Peak systolic velocity (PSV) and end-systolic velocity (or systolic nadir; Ns) were measured on all aortic isthmus waveforms. An ISI was derived from the ratio Ns/PSV. Left and right ventricular outputs were also calculated.

RESULTS

Up to 22-23 weeks' gestation, the mean ISI is stable at around 0.2. At about 28 weeks, a brief end-systolic deceleration wave is observed on the aortic isthmus waveforms, progressing steadily with gestation and causing a fall of ISI towards a mean value of zero between 30 and 31 weeks. This trend continues thereafter and a mean value of -0.4 was observed at the end of pregnancy. An inverse correlation was found between right ventricular output and Ns (r = -0.334, P = 0.001). Simultaneous recordings of the isthmus and the ductus arteriosus Doppler waveforms demonstrated that the primary cause of the end-systolic deceleration and ultimate reversal of flow at the isthmus is the increasingly dominant flow from the right ventricle.

CONCLUSION

The transitional changes of the respective right and left ventricular outputs throughout pregnancy are well profiled by the ISI. This index highlights the physiological increase in fetal right ventricle flow preponderance as pregnancy progresses. Alteration of the ISI profile could be expected in clinical conditions associated with unbalanced alteration of the fetal ventricular outputs.

Single arterial trunk arising from the aortic arch with aortic coarctation. Report of a case. Embryological considerations

Abnormalities of the aortic arch occur mainly due to an abnormal development of the fourth aortic arch in the first 12 weeks of fetal life. These abnormalities may be asymptomatic for a long period, or can develop clinically when vascular rings surround the trachea and esophagus and cause tracheal and/or esophageal obstruction. We present the case of a full-term newborn baby, male. The pregnancy had no medical surveillance from a family physician or an obstetrical. After five days of age, the infant died due to severe malformations, incompatible with life, respectively due to single arterial trunk and aorta coarctation. In the literature, there have been cited several other cases similar to our case; however, this one remains an extremely rare anomaly. We believe that the abnormality is due to a regression on an abnormal site of the fourth left aortic arch, but due to the very small number of these anomalies reported so far, we cannot say with certainty if there is an embryologic reason for these abnormalities.

Embryological-origin-dependent differences in homeobox expression in adult aorta: role in regional phenotypic variability and regulation of NF-κB activity

OBJECTIVE

Different vascular beds show differing susceptibility to the development of atherosclerosis, but the molecular mechanisms underlying these differences are incompletely understood. This study aims to identify factors that contribute to the phenotypic heterogeneity of distinct regions of the adult vasculature.

APPROACH AND RESULTS

High-throughput mRNA profiling in adult mice reveals higher expression of the homeobox paralogous genes 6 to 10 (Hox6-10) in the athero-resistant thoracic aorta (TA) than in the athero-susceptible aortic arch (AA). Higher homeobox gene expression also occurs in rat and porcine TA, and is maintained in primary smooth muscle cells isolated from TA (TA-SMCs) compared with cells from AA (AA-SMCs). This region-specific homeobox gene expression pattern is also observed in human embryonic stem cells differentiated into neuroectoderm-SMCs and paraxial mesoderm-SMCs, which give rise to AA-SMCs and TA-SMCs, respectively. We also find that, compared with AA and AA-SMCs, TA and TA-SMCs have lower activity of the proinflammatory and proatherogenic nuclear factor-κB (NF-κB) and lower expression of NF-κB target genes, at least in part attributable to HOXA9-dependent inhibition. Conversely, NF-κB inhibits HOXA9 promoter activity and mRNA expression in SMCs.

CONCLUSION

Our findings support a model of Hox6-10-specified positional identity in the adult vasculature that is established by embryonic cues independently of environmental factors and is conserved in different mammalian species. Differential homeobox gene expression contributes to maintaining phenotypic differences between SMCs from athero-resistant and athero-susceptible regions, at least in part through feedback regulatory mechanisms involving inflammatory mediators, for example, reciprocal inhibition between HOXA9 and NF-κB.

Critical transitions in early embryonic aortic arch patterning and hemodynamics

Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in the developing embryo, and observed that these two stages contained different aortic arch patterns with no inter-embryo variation. In the present study, we investigate these biomechanical events in the intermediate stage 21 to determine insights into this critical transition. We performed fluorescent dye microinjections to identify aortic arch patterns and measured diameters using both injection recordings and high-resolution optical coherence tomography. Flow and WSS were quantified with 3D computational fluid dynamics (CFD). Dye injections revealed that the transition in aortic arch pattern is not a uniform process and multiple configurations were documented at stage 21. CFD analysis showed that WSS is substantially elevated compared to both the previous (stage 18) and subsequent (stage 24) developmental time-points. These results demonstrate that acute increases in WSS are followed by a period of vascular remodeling to restore normative hemodynamic loading. Fluctuations in blood flow are one possible mechanism that impacts the timing of events such as aortic arch regression and generation, leading to the variable configurations at stage 21. Aortic arch variations noted during normal rapid vascular remodeling at stage 21 identify a temporal window of increased vulnerability to aberrant aortic arch morphogenesis with the potential for profound effects on subsequent cardiovascular morphogenesis.

Origin and course of the extracranial vertebral artery: CTA findings and embryologic considerations

PURPOSE

The aim of this study was to show the different origins and courses of the extracranial VA on CTA with special emphasis on embryological considerations. The duplicated VA is an anomaly that has been assumed to predispose for dissection and to be associated with aneurysms. We report its frequency and clinical significance.

METHODS

We retrospectively reviewed CTA of 539 patients by using a contrast-enhanced CTA protocol of the VA on CT.

RESULTS

Ninety-four-point-two percent of left VA originated from left subclavian artery and entered the transverse foramen at C6 in nearly all cases. Six-point-three-percent of left VA (m = 4 %, f  = 10 %) originated from the aortic arch and entered the transverse foramen either at C4, C5 or C7 but never at C6. One case of an aberrant retroesophageal right VA originated from the aortic arch distal to the left subclavian artery and entered at C7 (0.19 %). All other right VA originated from the right subclavian artery (99.8 %) and entered between C4 and C6. We diagnosed four cases of duplicated VA (0.74 %) with a female predominance (1.9 %) without any signs of dissection on CTA. Two cases with VA duplication had intracranial arterial aneurysms.

CONCLUSIONS

The VA is a longitudinal anastomosis of segmental metameric arteries. The level of entrance into the transverse foramen indicates which metameric artery or arteries persist. Duplication corresponds to persistence of two segmental arteries and is a rare phenomenon. VA duplication might be associated with vascular lesions.

Longitudinal study of aortic isthmus Doppler in appropriately grown and small-for-gestational-age fetuses with normal and abnormal umbilical artery Doppler

OBJECTIVE

To establish reference ranges using longitudinal data for aortic isthmus (AoI) Doppler indices in appropriate-for-gestational-age (AGA) fetuses and to document the longitudinal trends in a cohort of small-for-gestational-age (SGA) fetuses with normal umbilical artery Doppler and in fetuses with intrauterine growth restriction (IUGR) and abnormal umbilical artery Doppler.

METHODS

AoI Doppler reference ranges were established from longitudinal data on 72 AGA singleton fetuses. Reliability of AoI Doppler flow measurements at two different sites and reproducibility between two operators was reviewed. A prospective longitudinal study of AoI Doppler indices in 48 SGA fetuses with normal umbilical artery Doppler and 10 IUGR fetuses was performed.

RESULTS

The AoI pulsatility index (PI) and peak systolic velocity (PSV) in AGA fetuses showed a significant increase with gestational age. Analysis of intra- and interoperator variability revealed no significant mean difference in measurements of AoI-PI or AoI-PSV. Observations of AoI-PI and AoI-PSV from SGA fetuses did not differ significantly from those of AGA or IUGR fetuses. Retrograde flow in the AoI did not predate changes in the ductus venosus in IUGR fetuses.

CONCLUSIONS

Reference ranges for fetal AoI Doppler parameters in AGA fetuses constructed using longitudinal data are consistent with those obtained from cross-sectional data. The AoI Doppler parameters in SGA fetuses did not differ from those in AGA fetuses. Preterm IUGR fetuses did not manifest alterations in AoI-PI or AoI-PSV prior to changes in biophysical profile or ductus venosus Doppler. Further large-scale prospective studies are needed to determine whether AoI Doppler parameters are of any value in timing delivery or reducing adverse neurodevelopmental outcome.

Sequence of changes in myocardial performance index in relation to aortic isthmus and ductus venosus Doppler in fetuses with early-onset intrauterine growth restriction

OBJECTIVE

To explore the sequence of changes in myocardial performance index (MPI) and aortic isthmus (AoI) and ductus venosus (DV) flow in fetuses with early-onset intrauterine growth restriction (IUGR).

METHODS

MPI and AoI and DV pulsatility indices (PI) were evaluated every 1-7 days in a cohort of IUGR fetuses with abnormal umbilical artery Doppler PI (> 95(th) percentile) delivered before 34 weeks' gestation. The longitudinal changes were analyzed in the last 30 days before delivery by multilevel and survival analysis.

RESULTS

A total of 430 scans were performed on 115 IUGR fetuses. MPI, AoI-PI and DV-PI showed increases with the progression of fetal deterioration throughout the follow-up study period, but the rates of progression were different. On average, MPI, AoI-PI and DV-PI crossed the 95(th) percentile at 26 days, 12 days and 5 days before delivery, respectively. At the last examination before delivery, the proportion of increased MPI (70.4%) was significantly higher than that of abnormal AoI-PI (55.7%; P < 0.01) and DV-PI (47.8%; P < 0.01).

CONCLUSION

In early-onset IUGR, MPI and AoI and DV Doppler indices all increase but at different rates, which could provide the basis for further research on their use for improving in-utero monitoring and prediction of long-term outcome.

Baicalin increases VEGF expression and angiogenesis by activating the ERR{alpha}/PGC-1{alpha} pathway

AIMS

Baicalin is the major component found in Scutellaria baicalensis root, a widely used herb in traditional Chinese medicine. Although it has been used for thousands of years to treat stroke, the mechanisms of action of S. baicalensis have not been clearly elucidated. In this report, we studied the modulation of angiogenesis as one possible mechanism by investigating the effects of these agents on expression of vascular endothelial growth factor (VEGF), a critical factor for angiogenesis.

METHODS AND RESULTS

The effects of baicalin and an extract of S. baicalensis on VEGF expression were tested in several cell lines. Both agents induced VEGF expression in all cells without increasing expression of hypoxia-inducible factor-1α (HIF-1α). The expression of reporter genes was also activated under the control of the VEGF promoter containing either a functional or a defective HIF response element (HRE). Only minimal effects were observed on reporter activation under the HRE promoter. Instead, both agents significantly induced oestrogen-related receptor (ERRα) expression as well as the activity of reporter genes under the control of ERRα-binding element. Their ability to induce VEGF expression was suppressed once ERRα expression was knocked down by siRNA or ERRα-binding sites were deleted in the VEGF promoter. We also found that both agents stimulated cell migration and vessel sprout formation from the aorta.

CONCLUSION

Our results implicate baicalin and S. baicalensis in angiogenesis by inducing VEGF expression through the activation of the ERRα pathway. These data may facilitate a better understanding of the potential health benefits of these agents in the treatment of cardiovascular diseases.

The 'question mark' sign as a new ultrasound marker of tetralogy of Fallot in the fetus

OBJECTIVE

To describe a new ultrasonographic marker, the 'question-mark' sign, to assist in the diagnosis of tetralogy of Fallot (TOF) in the fetus, and to evaluate its prevalence in TOF as compared with other cardiac defects.

METHODS

A prospective evaluation over a 5-year period of a consecutive series of 3998 pregnant women undergoing fetal echocardiography from 12 to 40 weeks' gestation due to high risk for congenital heart disease (CHD). Standard echocardiographic planes with color Doppler assessment and evaluation of the whole aortic arch, from the left ventricular outflow tract to the descending aorta in the axial upper mediastinum views, were performed. The question-mark sign corresponded with an enlarged and dilated ascending aorta and aortic arch in the three-vessel view of the upper fetal mediastinum. The frequency of this sign was evaluated in cases with TOF and in other cases of cardiac defects, as well as in fetuses with normal cardiac scans in this series.

RESULTS

CHD was diagnosed in a total of 447 (11.2%) fetuses at a median gestational age of 24 (range, 12-40) weeks. Forty-two of the 447 (9.4%) had TOF, of which 29 cases (69.0%) had classical TOF (pulmonary stenosis), nine (21.4%) pulmonary atresia and four (9.5%) absent pulmonary valve syndrome. A question-mark sign was observed in 16/29 (55.2%) cases of classical TOF and in 8/9 (88.9%) cases of TOF with pulmonary atresia. The sign was never observed in any of the cases of TOF with a right-sided aortic arch. Likewise, the sign was observed in 1/405 (0.2%) cases with other cardiac anomalies (a fetus with a complex cardiac defect) and in none of the fetuses with normal hearts.

CONCLUSIONS

The finding of an enlarged aorta with a question-mark shape should raise a strong suspicion of tetralogy of Fallot, in particular the variant with pulmonary atresia. This sign may be useful in screening considering that prenatal diagnosis of TOF by routine ultrasonography remains a challenge.

In utero exposure to maternal diabetes impairs vascular expression of prostacyclin receptor in rat offspring

OBJECTIVE

To evaluate modifications of arterial structure, gene expression, and function in our model of rats exposed to maternal diabetes.

RESEARCH DESIGN AND METHODS

Morphometric analyses of elastic vessels structure and determination of thoracic aortic gene expression profile with oligonucleotide chips (Agilent, G4130, 22k) were performed before the onset of established hypertension (3 months).

RESULTS

Arterial parameters of in situ fixed thoracic aorta were not significantly different between control mother offspring and diabetic mother offspring (DMO). The aortic gene expression profile of DMO is characterized by modifications of several members of the arachidonic acid metabolism including a twofold underexpression of prostacyclin receptor, which could contribute to decreased vasodilatation. This was confirmed by ex vivo experiments on isolated aortic rings. Pharmacological studies on conscious rats showed that systolic blood pressure decline in response to a PGI(2) analog was impaired in DMO rats.

CONCLUSIONS

These results suggest an abnormal vascular fetal programming of prostacyclin receptor in rats exposed in utero to maternal hyperglycemia that is associated with impaired vasodilatation and may be involved in the pathophysiology of hypertension in this model.

Defining laterality of the descending thoracic aorta in a 4-chamber view of the heart

OBJECTIVE

Right descending aortas have been correlated with an increased risk of congenital heart disease. Nevertheless, the aortic position remains a largely overlooked diagnostic tool in second-trimester sonography because no formal system for assessing the position exists. By developing a method of assigning the position of the aorta relative to the thoracic midline, diagnostic use of the descending aorta's position might be implemented more easily.

METHODS

The method of assessing the position relative to the midline was tested by comparing the analysis of 2 independent observers, who showed a 94.4% concordance rate.

RESULTS

Comparison of the percentages of aortic positions between the gestational ages (GAs) of 18 and 21 weeks showed no significant correlation between the aortic position and GA.

CONCLUSIONS

We suggest simply paying attention to the aortic position in an already standard view. The extra effort is minimal, and it has the potential to improve the diagnostic accuracy of the 4-chamber view.

Arch of aorta with bi-carotid trunk, left subclavian artery, and retroesophageal right subclavian artery

We report a case of left sided aortic arch with three branches - a bi-carotid trunk, left subclavian, artery and right subclavian artery. The anomalous right subclavian artery presented a retroesophageal course. A right non-recurrent laryngeal nerve was noticed. The embryonic development of this branching pattern is discussed.

Sonographic measurements of the fetal fastigium between 20 and 40 weeks' gestation

OBJECTIVE

The purpose of this study was to establish a new reference angle chart for fastigial biometric measurements throughout gestation in normal singleton pregnancies.

METHODS

A prospective cohort study was designed. A total of 505 pregnant women between 20 and 40 weeks' gestation were included in the study. Excluded were those with multiple pregnancies, congenital anomalies, abnormal karyotypes, and polyhydramnios or oligohydramnios. Transvaginal or transabdominal sonography was performed in the midsagittal plane of the brain.

RESULTS

The angle of the fastigium was found to be 30 degrees to 60 degrees throughout pregnancy. These data were found to be constant during the progression of pregnancy without any significant changes.

CONCLUSIONS

Fastigial measurements throughout pregnancy are presented. Its angle is constant throughout pregnancy. Evaluation of the fastigium may assist in cases of subtle posterior fossa anomalies.

Fetal aortic arch measurements at 14 to 40 weeks' gestation derived by spatiotemporal image correlation volume data sets

OBJECTIVE

The purpose of this study was to establish reference ranges for the transverse aortic arch diameter (TAD) and distal aortic isthmus diameter (DAID) in normal singleton pregnancies (14-40 weeks) based on the 3-vessel/trachea (3VT) view of cardio-spatiotemporal image correlation (STIC) volume data sets.

METHODS

A prospective descriptive study was conducted on uncomplicated singleton pregnancies with healthy fetuses and an accurate gestational age (GA). Cardio-STIC examinations were performed by experienced sonographers using a high-resolution ultrasound machine, and the volume data sets were manipulated to obtain the 3VT view and measured for the TAD and DAID.

RESULTS

A total of 554 measurements were performed, ranging from 13 to 30 for each gestational week. The best regression models were as follows: TAD (in millimeters) = -1.01 + 1.69 (GA, in weeks) (r(2) = 0.93; P < .001), and DAID (in millimeters) = -0.85 + 1.54 (GA, in weeks) (r(2) = 0.92; P < .001). A table of nomograms for 5th, 50th, and 95th percentile ranges was constructed.

CONCLUSIONS

Normative data for the TAD and DAID at each gestational week from 14 to 40 weeks were constructed by a new technique of measurement based on cardio-STIC. These reference ranges may be useful tools for assessment of fetal aortic arch abnormalities.

Feasibility and reliability of Doppler flow recordings in the fetal aortic isthmus: a multicenter evaluation

OBJECTIVES

To evaluate the performance of three different centers with respect to their ability to identify the fetal aortic isthmus (AoI) adequately and place a Doppler sample volume in the AoI correctly, and to address the reproducibility of the isthmic flow index (IFI) calculated from Doppler waveforms recorded in the three centers.

METHODS

The three collaborating centers sent several ultrasonographic recordings taken at random over a 6-week period to the Saint-Justine Fetal Cardiology Unit (StJ-FCU). A performance quotient ((number of total readings - number of unsatisfactory results)/number of total readings) was calculated for each center by each of three judges, who were experienced fetal cardiologists, to assess the ability of each center to identify the isthmus and to place the Doppler sample volume (DSV) adequately. Intraclass correlation coefficients (ICC) were computed to quantify the variability of IFI measurements ((systolic + diastolic)/systolic flow velocity integrals).

RESULTS

Fifty-five recordings were available for this study. Concerning isthmus identification, there was 100% agreement between the three judges from StJ-FCU and the performance quotients of Centers A, B and C were: 0.90, 0.95 and 1.00, respectively. For DSV positioning, agreement between the judges varied; for Judge 1 vs. Judge 2, kappa = 0.836 (95% CI, 0.651-1.000); for Judge 1 vs. Judge 3, kappa = 0.773 (95% CI, 0.557-1.000); for Judge 2 vs. Judge 3, kappa = 0.941 (95% CI, 0.805-1.000). The performance quotients of the three centers for DSV positioning were consistently lower than were those for identification of the isthmus, being 0.85, 0.76 and 0.92, respectively. The ICC between the first and second measurements of the IFI by Rater 1 was 0.96 (95% CI, 0.93-0.98, P < 0.001) and that between Raters 1 and 2 was 0.97 (95% CI, 0.95-0.99, P < 0.001).

CONCLUSION

Adequate imaging of the fetal AoI can be achieved easily by a trained sonographer, while DSV positioning is challenging. The intra- and interrater variability of the IFI are low.

Three-dimensional sonography in the prenatal diagnosis of aortic arch abnormalities

PURPOSE

To assess the added value of 3-dimensional (3D) echocardiography with spatiotemporal image correlation (STIC) in the diagnosis of aortic arch abnormalities in fetuses with isolated abnormal upper thoracic 3-vessel view (3VV).

METHOD

A total of 3,420 women underwent a targeted anatomic survey at 18-22 weeks' gestation in a 1-year period. An isolated abnormal upper thoracic 3VV detected on 2-dimensional (2D) imaging was followed up by conventional 2D echocardiography and 3D fetal echocardiography with STIC. Offline reconstruction by a second operator blinded to the suspected diagnosis was performed. Neonatal echocardiography and MRI with 3D reconstruction were performed to verify the prenatal diagnosis.

RESULT

Of the 3,420 patients referred, 4 had an isolated abnormal 3VV (0.09%). A right-sided aortic arch (RAA, n = 3) and double aortic arch (DAA, n = 1) were suspected. In all aortic arch abnormalities, 3D fetal echocardiography and STIC correctly identified RAA with aberrant left subclavian artery in 3 cases and DAA in 1 case with a degree of definition that was equal to the confirmatory postnatal echocardiography and 3D MRI.

CONCLUSION

Although the 2D upper 3VV is a powerful screening tool for isolated aortic arch abnormalities, 3D fetal echocardiography with STIC allows an accurate prenatal characterization of the abnormality to a degree that is typically attainable only by post partum imaging.

Monitoring of fetuses with intrauterine growth restriction: longitudinal changes in ductus venosus and aortic isthmus flow

OBJECTIVES

To explore in growth-restricted fetuses the sequence of changes in aortic isthmus and ductus venosus blood flow in relation to other arterial Doppler parameters commonly used to evaluate fetal wellbeing.

METHODS

Umbilical and middle cerebral arteries, ductus venosus and aortic isthmus were explored serially by means of pulsed Doppler in a cohort of singleton small-for-gestational age fetuses requiring delivery before 34 weeks. Longitudinal changes in the last 30 days before delivery were modeled by multilevel analysis. Individual regression lines for each variable were calculated for each fetus and from these the regression lines for the whole group were derived, in order to estimate the mean time point at which each Doppler parameter became abnormal (outside the 5th-95th centile range). A survival analysis was performed during the monitoring period, in which the endpoint was an abnormal Doppler pulsatility index.

RESULTS

A total of 162 observations were performed on 46 fetuses (median, 3; range, 2-10). The median gestational age at inclusion was 28.9 (range, 23.6-33.4) weeks and delivery occurred at a median gestational age of 30.5 (range, 25.9-33.9) weeks. Six (13%) cases of perinatal mortality occurred. Umbilical and middle cerebral artery Doppler showed an almost linear deterioration throughout monitoring, becoming abnormal on average 24 days and 20 days before delivery, respectively. Aortic isthmus Doppler became abnormal on average 13 days before delivery, while ductus venosus Doppler did so within the last week before delivery.

CONCLUSIONS

In preterm growth-restricted fetuses, aortic isthmus blood flow becomes abnormal on average 1 week earlier than does that in the ductus venosus. This could provide a sound basis to better define management protocols aimed to improve intact fetal survival.

Relationship between aortic isthmus and ductus venosus velocity waveforms in severe growth restricted fetuses

OBJECTIVE

To evaluate the incidence of abnormalities in velocity waveforms from ductus venosus (DV) and aortic isthmus (AoI) in fetuses with intrauterine growth restriction (IUGR) and their reciprocal temporal relationship.

METHODS

DV and AoI velocity waveforms were recorded in 31 IUGR fetuses characterized either by absent end diastolic (20) or reverse flow (11) in umbilical artery. Abnormal velocity waveforms in DV and AoI were defined in presence of reverse diastolic flows.

RESULTS

Abnormal DV velocity waveforms were present in 10 fetuses and were always associated with abnormalities. Abnormal AoI flows were also present in 10 fetuses of the remaining 21 fetuses with normal DV velocity waveforms (47.6%). Longitudinal monitoring of fetuses with normal DV flows showed a significantly shorter time interval in the onset of reverse flow in DV when abnormalities in AoI were present (4 vs 14 days p=0.001) irrespectively of gestational age or other potential confounding variables.

CONCLUSIONS

Our data suggest that AoI velocity waveforms become abnormal at an earlier stage of fetal compromise than DV.

Length growth of the various aortic segments in human foetuses

This study defines normal growth for the various aortic segments in 128 spontaneously aborted human foetuses aged 15-34 weeks. With the use of anatomical dissection, digital-image analysis (using the Leica Q Win Pro 16 system) and statistical analysis (ANOVA, regression equation), a range of length measurements for the ascending aorta, aortic arch and thoracic aorta was examined. No significant gender differences were found (p > or = 0.05). The length of the ascending aorta ranged from 2.63 +/- 0.42 to 10.80 +/- 1.49 mm, according to the linear function y = -4.678 + 0.4647 x +/- 0.8447. The aortic arch length increased from 3.93 +/- 0.57 to 15.25 +/- 1.98 mm, in accordance with the linear model y = -6.079 + 0.6370 x +/- 1.1133. The length of the thoracic aorta ranged from 12.49 +/- 1.85 to 48.82 +/- 6.31 mm, according to the linear pattern y = -19.654 + 2.0512 x +/- 3.5168. The sum of the lengths of these aortic segments generated the linear function y = -30.410 + 3.153 x +/- 5.4332. The relationships between the lengths of the various aortic segments generated the linear regressions: y = -0.2256 + 0.7276 x +/- 0.3093 (for the ascending aorta vs. the aortic arch), y = 0.0252 + 0.3105 x +/- 0.2189 (for the aortic arch vs. the thoracic aorta), and y = -0.2408 + 0.22709 x +/- 0.2026 (for the ascending aorta vs. the thoracic aorta). The ascending aorta, aortic arch and thoracic aorta also increased proportionally (5:7:22) during gestation.