Pathology and molecular mechanisms of coarctation of the aorta and its association with the ductus arteriosus

The role of 3D technology in the practical education of congenital coarctation and its treatment-a feasibility pilot study

BACKGROUND

Coarctation of the aorta (CoA) is a congenital disease with an incidence of 4 out of 10,000 live births, therefore proper education of its treatment is essential. Understanding the disease and the wide array of treatment options is often difficult. Additive manufacturing technology can be used to produce 3D printed hands-on surgical training tools (HOSTT), which can be used for the education and practical training of CoA. This study aimed to investigate the effectiveness of a 3D printable HOSTT for the simulation of coarctation surgery, and it' possible role in practical education.

METHODS

Participants were medical students of Semmelweis University between the second and sixth academic year. A virtual 3D model of an aorta with CoA was generated from a computed tomography angiography scan. Each participant received a 3D-printed aorta phantom and performed either one of four surgical treatment modalities. The simulated surgeries included end-to-end anastomosis, end-to-side anastomosis, prosthetic patch, and subclavian flap aortoplasty. Participants provided feedback, evaluating their understanding of the disease and its treatment by the four surgical reconstruction modalities on a seven-point Likert scale before and after the sessions.

RESULTS

21 medical students participated in this study. Participants' average rating of their understanding of CoA disease and it treatment options before practical training was 4.62 ± 1.07. After training, their average rating increased to 6.19 ± 1.08, showing statistically significant difference.

CONCLUSIONS

Within this study's limitations, the applied HOSTT, manufactured using 3D printing, was effective for the practical training of CoA's surgical treatment methods for medical students.

Prenatal exposure to ambient air pollutants and congenital heart defects: An umbrella review

BACKGROUND

Prenatal exposure to ambient air pollutants has been linked to congenital heart defects (CHD), but findings of existing systematic reviews have been mixed.

OBJECTIVE

To assess the epidemiological evidence on associations between prenatal exposure to ambient air pollutants and CHD subtypes, based on a systematic overview of reviews ("umbrella review").

METHODS

We conducted a systematic search for reviews assessing associations between prenatal exposure to criteria air pollutants and CHD. The risk of bias was evaluated using the Risk of Bias in Systematic Reviews (ROBIS) tool. The certainty of the systematic review findings was graded using the Navigation Guide methodology.

RESULTS

We identified eleven systematic reviews, including eight with meta-analyses, assessing in total 35 primary studies of prenatal exposure to criteria air pollutants and various CHD subtypes. The certainty of the findings of four meta-analyses indicating an increased risk for coarctation of the aorta associated with nitrogen dioxide exposure was rated as moderate. The certainty of findings indicating positive, inverse, or null associations for other pollutant-subtype combinations was rated as very low to low, based on low precision and high statistical heterogeneity of summary odds ratios (SOR), substantial inconsistencies between review findings, and methodological limitations of the systematic reviews.

DISCUSSION

The inconsistent findings and high statistical heterogeneity of many SOR of the included systematic reviews may partly be traced to differences in methodological approaches, and the risk of bias across included reviews (e.g., inclusion criteria, systematic search strategies, synthesis methods) and primary studies (e.g., exposure assessment, diagnostic criteria). Adherence to appropriate systematic review guidelines for environmental health research, as well as rigorous evaluation of risk of bias in primary studies, are essential for future risk assessments and policy-making. Still, our findings suggest that prenatal exposure to ambient air pollutants may increase risks for at least some CHD subtypes.

Preductal Segmental Tubular Aortic Hypoplasia in Perinatally Died Stabyhoun Puppies

BACKGROUND

A high perinatal mortality rate in the Stabyhoun breed prompted one of the Dutch breeding organizations to start an investigation. Preductal segmental tubular aortic hypoplasia is an extremely rarely documented congenital vascular anomaly in dogs, and it is suspected to be the result of constriction of ectopic ductal tissue in the aortic wall at birth.

METHODS

Over a period of 18 months, Stabyhoun puppies that were stillborn, died or were euthanized before 3 weeks of age were submitted to post-mortem examination at the reporting institution. Pathologic findings were documented.

RESULTS

Eight Stabyhoun puppies were submitted during the study period. In five of them, a severe preductal segmental tubular aortic hypoplasia was found. Two of the five puppies were stillborn, and three died spontaneously or were euthanized.

CONCLUSIONS

Preductal tubular aortic hypoplasia was found in an unusually high frequency in the examined Stabyhoun puppies. Because the condition is believed to cause clinical signs only after birth, this anomaly cannot explain the death of the stillborn puppies. However, it might be responsible for cardiogenic pulmonary edema in the postnatal period. Routine dissection of the great vessels in perinatally deceased puppies would help to establish the prevalence of congenital anomalies of the aorta.

Diagnosis and surgical outcomes of coarctation of the aorta in pediatric patients: a retrospective study

BACKGROUND

Coarctation of the aorta (CoA) is a common congenital cardiovascular malformation, and improvements in the diagnostic process for surgical decision-making are important. We sought to compare the diagnostic accuracy of transthoracic echocardiography (TTE) with computed tomographic angiography (CTA) to diagnose CoA.

METHODS

We retrospectively reviewed 197 cases of CoA diagnosed by TTE and CTA and confirmed at surgery from July 2009 to August 2019.

RESULTS

The surgical findings confirmed that 19 patients (9.6%) had isolated CoA and 178 (90.4%) had CoA combined with other congenital cardiovascular malformations. The diagnostic accuracy of CoA by CTA was significantly higher than that of TTE (χ2 = 6.52, p = 0.01). In contrast, the diagnostic accuracy of TTE for associated cardiovascular malformations of CoA was significantly higher than that of CTA (χ2 = 15.36, p < 0.0001). Infants and young children had more preductal type of CoA, and PDA was the most frequent cardiovascular lesion associated with CoA. The pressure gradient was significantly decreased after the first operation, similar at 6 months, 1 year, and 3 years follow-ups by TTE.

CONCLUSIONS

CTA is more accurate as a clinical tool for diagnosing CoA; however, TTE with color Doppler can better identify associated congenital cardiovascular malformations. Therefore, combining TTE and CTA would benefit clinical evaluation and management in patients suspected of CoA. TTE was valuable for post-operation follow-up and clinical management.

Adaptive Growth of the Ductus Arteriosus and Aortic Isthmus in Various Ductus-Dependent Complex Congenital Heart Diseases

BACKGROUND

The ductus arteriosus (DA) is critical in maintaining postnatal circulation in neonates with obstructed systemic circulation (OSC) and pulmonary circulation (OPC). We hypothesized that the size of the DA and aortic isthmus (AoI) undergoes adaptive growth in utero to counteract the hemodynamic challenges in these congenital heart diseases (CHD).

METHODS

Postnatal echocardiograms of neonates diagnosed prenatally with ductal-dependent CHD who were started on prostaglandins within 24 h of birth were reviewed. We assessed the cross-sectional area of the aortic valve opening, pulmonary valve opening, AoI, and DA by calculating (diameter)²/body surface area. Neonates were classified into OSC or OPC then subgrouped depending upon the patency of semilunar valves: OSC with and without aortic atresia (OSC-AA and OSC-nAA, respectively) and OPC with and without pulmonary atresia (OPC-PA and OPC-nPA, respectively).

RESULTS

Ninety-four cases were studied. The DA in OSC was significantly larger than OPC, and the DA in OSC-AA was significantly larger than OSC-nAA. The size of the AoI was significantly larger in OPC than OSC and larger in OSC-AA than OSC-nAA. Within the OSC-nAA group, there was no significant difference in the size of the DA, AoI, or pulmonary valve opening between those with retrograde flow (RF) at the AoI and without (nRF) except the aortic valve opening was significantly larger in nRF. All groups had comparable cross-sectional areas of systemic output.

CONCLUSIONS

Our findings suggest that DA and AoI show compensatory growth to maintain critical blood flow to vital organs against primary anatomical abnormalities in ductus-dependent CHD. (249 words).

Coarctation of the Aorta: Diagnosis and Management

Coarctation of the aorta (CoA) accounts for approximately 5-8% of all congenital heart defects. Depending on the severity of the CoA and the presence of associated cardiac lesions, the clinical presentation and age vary. Developments in diagnosis and management have improved outcomes in this patient population. Even after timely repair, it is important to regularly screen for hypertension. Patients with CoA require lifelong follow-up with a congenital heart disease specialist as these patients may develop recoarctation and complications at the repair site and remain at enhanced cardiovascular risk throughout their lifetime.

Learning the Hidden Signature of Fetal Arch Anatomy: a Three-Dimensional Shape Analysis in Suspected Coarctation of the Aorta

Neonatal coarctation of the aorta (CoA) is a common congenital heart defect. Its antenatal diagnosis remains challenging, and its pathophysiology is poorly understood. We present a novel statistical shape modeling (SSM) pipeline to study the role and predictive value of arch shape in CoA in utero. Cardiac magnetic resonance imaging (CMR) data of 112 fetuses with suspected CoA was acquired and motion-corrected to three-dimensional volumes. Centerlines from fetal arches were extracted and used to build a statistical shape model capturing relevant anatomical variations. A linear discriminant analysis was used to find the optimal axis between CoA and false positive cases. The CoA shape risk score classified cases with an area under the curve of 0.907. We demonstrate the feasibility of applying a SSM pipeline to three-dimensional fetal CMR data while providing novel insights into the anatomical determinants of CoA and the relevance of in utero arch anatomy for antenatal diagnosis of CoA.

Utility of novel echocardiographic measurements to improve prenatal diagnosis of coarctation of the aorta

Prenatal recognition of coarctation of the aorta (CoA) may improve neonatal survival and reduce morbidity. However, prenatal diagnosis of CoA remains challenging, with relatively high false-positive and false-negative rates. This study aimed to identify a novel formula based on fetal echocardiographic measures to predict prenatal identification of CoA. A retrospective comparison on the echocardiographic evaluation of 30 patients with suspected CoA between May 2016 and April 2021 was performed. The patients were divided into a postnatal surgical intervention group (n = 13) and a non-intervention group (n = 17). The measurements that showed significant differences were aortic isthmus diameter Z-score (p < 0.001), ductus arteriosus diameter/aortic isthmus diameter (p < 0.001), and distal aortic arch (DA) index (p < 0.001). In the receiver operating characteristic curves analysis, the DA index was the largest with an area under the curve of 0.941 and a cutoff value of 1.28, with a sensitivity of 85% and a specificity of 94%. Measurement of the DA index improved the diagnostic rate of fetal CoA and a DA index ≧ 1.28 indicated fetal CoA cases requiring surgical intervention.

Late open conversion after endovascular treatment for the coarctation of aorta in adult due to restenosis with thrombus

A 22-year-old man was referred to our hospital for rib notching found on a radiograph and hypertension. Computed tomography revealed coarctation of the descending aortic isthmus. Because he refused open surgery, endovascular treatment was performed. The 2-year follow-up computed tomography scan showed infolding of the stent graft and thrombus formation. He had presented with intermittent claudication; therefore, graft interposition was performed. Endovascular surgery plays an important role in the treatment of coarctation of the aorta. However, insufficient dilatation can lead to restenosis accompanied by thrombus formation, and excess ballooning can cause aortic wall injury. Careful performance of the procedure and close postoperative follow-up are essential.

Multi-centre cross-sectional study on vascular remodelling in children following successful coarctation correction

Coarctation of the aorta is an arteriopathy with life-long sequelae, with remarkably increased cardiovascular events in young adults even after successful repair and despite blood pressure status. There are data on arterial remodelling in adults after coarctation correction, however, these data are scarce in childhood. Thus, the aim of this cross-sectional study was to evaluate changes in arterial wall function and morphology in children following successful coarctation repair and to compare these changes among patients with different blood pressure status and coarctation correction modes. Blood pressure status, echocardiographic parameters, arterial wall structure and stiffness, endothelial function and central blood pressure measurements were evaluated in 110 children aged 6-18 years following successful coarctation repair with right arm blood pressure not exceeding leg blood pressure by ≥20 mmHg. The prevalence of arterial hypertension was 50%. The mean carotid intima-media thickness SDS was 3.1 ± 1.5 and above 1.65 SDS in 91 of 110 patients. Increased right carotid intima-media thickness was associated with left ventricular hypertrophy, office blood pressure difference between leg and right arm, recoarctation in the past and interventional coarctation correction. Increased local common carotid artery stiffness was associated with increased pulse pressure and central systolic blood pressure. Potentially decreased endothelial function was related to a slight increase of peak and mean systolic gradient in the descending aorta. After successful coarctation repair and with a low blood pressure gradient, children still have a high prevalence of arterial hypertension and significant arterial remodelling, indicating accelerated biological age and advanced arteriosclerosis.

Incremental value of myocardial deformation in predicting postnatal coarctation of the aorta: establishment of a novel diagnostic model

BACKGROUND

Prenatal detection of coarctation of the aorta (CoA) still suffers from high false-positive and false-negative rates. The objective of this study was to develop a novel model to improve the diagnostic accuracy of fetal CoA.

METHODS

A retrospective study was conducted in 122 fetuses with suspected CoA who also had postnatal follow-ups. Fetuses with confirmed diagnosis of CoA after birth were defined as CoA group, and Non-CoA group were those false-positives. Conventional fetal echocardiographic measurements, including great arterial dimensions and flow characteristics were obtained. Left ventricular (LV) functional parameters were determined using two-dimensional speckle tracking echocardiography. A novel multi-parametric diagnostic model, including gestational age (GA) at diagnosis, aortic isthmus (AOI) Z-score and LV longitudinal strain (LVLS), was developed by univariate and multivariate logistic regression analyses. The model was validated prospectively by a validation cohort of 48 fetuses.

RESULTS

CoA was confirmed in 62/122 (50.8%) cases after birth. Fetuses with postnatal CoA were diagnosed significantly earlier than false-positives (median (interquartile range), 24.5 (23.3-26.4) vs 27.8 (24.5-30.4) weeks; P < .001). The Z-scores of aortic dimensions (aortic valve annulus, ascending aorta, transverse aortic arch and AOI) were significantly smaller (all P < .001), while the Z-scores of pulmonary dimensions (pulmonary valve annulus and main pulmonary artery) were significantly greater (all P < .05), in cases of confirmed CoA than false-positives. Compared with Non-CoA group, CoA group displayed lower LV ejection fraction (P = .005), LV fractional area change (P < .001) and LVLS (P < .001). A multivariate logistic regression model incorporating GA (odds ratio (OR): 0.74, 95% confidence interval (CI): 0.60-0.88; P = .001), AOI Z-score (OR: 0.20, 95% CI: 0.08-0.41; P < .001) and LVLS (OR: 1.79, 95% CI: 1.41-2.42; P < .001) was established to diagnose CoA more accurately (Akaike information criterion: 81.77, C-statistics: 0.945). The performance of this model was confirmed prospectively in the validation cohort.

CONCLUSIONS

In fetuses with suspected CoA, speckle tracking analysis of LVLS may have an incremental value in predicting postnatal CoA. Our diagnostic model, including GA, AOI Z-score and LVLS, may provide a good tool for the stratification of the risk in fetal CoA and contribute to patient-specific perinatal management.

Coarctation of the aorta: Prenatal assessment, postnatal management and neonatal outcomes

Coarctation of the aorta (Coa) is a potentially life threatening diagnosis. It occurs in 0.3 per 1000 live births and accounts for 6-8% of all infants with congenital heart defects. Neonates with severe Coa may be completely asymptomatic at birth, as the ductus arteriosus can provide flow to the lower body. Those who are not diagnosed prenatally may be diagnosed only after constriction of the ductus arteriosus, when they present in cardiogenic shock. This group has a higher risk for mortality and morbidity relative to those diagnosed prenatally. Despite the increasing practice of universal pulse oximetry screening, many cases with significant coarctation of the aorta still go undiagnosed in the newborn period. In this article, we present the pathophysiology, diagnosis, presentation, treatment and outcomes of Coa.

Physiological fetal vascular shunts and failure to regress: what the radiologist needs to know

The fetal circulation is characterized by the presence of three physiological vascular shunts - the ductus arteriosus, the foramen ovale and the ductus venosus. Acting in concert, these shunts preferentially stream blood flow in a pattern that maximizes efficiency of blood oxygenation by the maternofetal unit. Shortly following the transition to extrauterine life, a quick and predetermined succession of events results in closure of these embryological structures with consequent establishment of postnatal vascular flow patterns. While this transition is often seamless, the physiological shunts of the fetus occasionally fail to regress. Such failure to regress can occur in isolation or in association with other congenital malformations. This failed regression challenges the circulatory physiology of the neonate and might have implications for the optimum functioning of several organ systems. When symptomatic, these shunts are treated. Interventions, when undertaken, might be medical, endovascular or surgical. The radiologist's role continues to expand in the assessment of these shunts, in providing a roadmap for treatment and in prompt identification of treatment-related complications. This review is to familiarize radiologists with the embryology, pre- and post-treatment imaging appearances, and associated complications of persistent fetal vascular shunts.

Isolated Coarctation of the Aorta: Current Concepts and Perspectives

Current management of isolated CoA, localized narrowing of the aortic arch in the absence of other congenital heart disease, is a success story with improved prenatal diagnosis, high survival and improved understanding of long-term complication. Isolated CoA has heterogenous presentations, complex etiologic mechanisms, and progressive pathophysiologic changes that influence outcome. End-to-end or extended end-to-end anastomosis are the favored surgical approaches for isolated CoA in infants and transcatheter intervention is favored for children and adults. Primary stent placement is the procedure of choice in larger children and adults. Most adults with treated isolated CoA thrive, have normal daily activities, and undergo successful childbirth. Fetal echocardiography is the cornerstone of prenatal counseling and genetic testing is recommended. Advanced 3D imaging identifies aortic complications and myocardial dysfunction and guides individualized therapies including re-intervention. Adult CHD program enrollment is recommended. Longer follow-up data are needed to determine the frequency and severity of aneurysm formation, myocardial dysfunction, and whether childhood lifestyle modifications reduce late-onset complications.

Prospective multicenter study of the breakable babystent for treatment of aortic coarctation in newborns and infants

To assess the efficacy and safety of a breakable BabyStent to treat complex aortic coarctation (CoA) in early childhood. Although recommended in several guidelines, there is no approved aortic stent for young infants, because of the dilemma between two mandatory requirements: expandable up to adult size on the one hand, and small enough to fit through a baby's femoral artery on the other. Prospective interventional, multi-center clinical trial with the breakable Osypka BabyStent® (OBS). The OBS is a low-profile, 15-mm long cobalt-chromium stent, pre-mounted on a 6 mm balloon and inserted via a 4 Fr sheath. After implantation, its diameter is adjustable from 6 to 12 mm by balloon dilation. Further dilation opens predefined joints enabling unrestricted growth. Nineteen patients (9 male), median age 112 days (range: 7-539), median body weight 5.6 kg (range: 2.4-8.4) were deemed high risk and underwent stent implantation. Of those, 74% suffered from re-CoA following surgery, 53% had additional cardiac and 21% noncardiac malformations. Our primary combined endpoint was fulfilled: All stents were implanted in the desired region, and a >50% intrastenotic diameter-extension was achieved in 15 patients (78.9%, 80% confidence interval [62.2; 90.5], 95% confidence interval [54.4; 93.9]). Secondary endpoint confirmed that the OBS fits the baby's femoral vessel diameter. All children survived the procedure and 12-month follow-up. This stent enables percutaneous stenting of complex aortic coarctation to treat high-risk newborns and infants.

Necessity of life-long follow-up after surgery for coarctation of the aorta: a case series of very late false aneurysm formation

BACKGROUND

Coarctation of the aorta accounts for 5-7% of congenital defects of the heart and great vessels. It requires treatment in the form of open surgical or percutaneous repair. Common long-term complications include re-stenosis and aneurysm formation. The formation of a false aneurysm is a complication with a significant morbidity and mortality.

CASE SUMMARY

We reviewed six cases of late false aneurysm after repair of a coarctation of the aorta. Our six cases developed a false aneurysm after an open surgical repair of a coarctation more than 30 years after initial surgical repair. All aneurysms were located at the aortic repair site.

DISCUSSION

The symptoms or risk factors in the described cases are not uniform and are difficult to include in a general follow-up protocol. Guidelines recommend frequent evaluation, but do not specify duration or intervals of imaging follow-up. Our cases support the necessity of life-long follow-up in patients with open aortic repairs irrespective of symptomatology.

Congenital Heart Disease in Adults with Autosomal Dominant Polycystic Kidney Disease

INTRODUCTION

Autosomal dominant polycystic kidney disease (ADPKD) is caused mainly by pathogenic variants in PKD1 or PKD2 encoding the polycystin-1 and -2 proteins. Polycystins have shown to have an essential role in cardiac development and function in animal models. In the current study, we describe the clinical association between ADPKD and congenital heart disease (CHD).

METHODS

Medical records from Mayo Clinic were queried for all patients with confirmed ADPKD and CHD between 1993 and 2020. CHD was categorized into left-to-right shunt, obstructive, and complex lesions. Patent foramen ovale, mitral valve prolapse, and bicuspid aortic valve anomalies were excluded.

RESULTS

Twenty-five out of 1,359 (1.84%) ADPKD patients were identified to have CHD. Of these, 84% were Caucasians and 44% were males. The median (Q1-Q3) age (years) at CHD diagnosis was 12.0 (2.0-43.5). Fourteen patients (56%) had left-to-right shunt lesions, 6 (24%) had obstructive lesions and 5 (20%) complex lesions. Seventeen patients (68%) had their defects surgically corrected at a median age (Q1-Q3) of 5.5 (2.0-24.7). Among 13 patients with available genetic testing, 12 (92.3%) had PKD1 pathogenic variants, and none had PKD2. The median (Q1-Q3) age at last follow-up visit was 47.0 (32.0-62.0) and median (Q1-Q3) eGFR was 35.8 (11.4-79.0) mL/min/1.73 m2. Three patients (12%) died; all of them had left-to-right shunt lesions.

DISCUSSION/CONCLUSION

We observed a higher CHD frequency in ADPKD than the general population (1.84 vs. 0.4%). While only PKD1 pathogenic variants were identified in this cohort, further studies are needed to confirm this novel finding and understand the role of polycystins in the development of the heart and vessels.

RNA sequencing analyses in infants patients with coarctation of the aorta

BACKGROUND

Coarctation of the aorta (CoA) is a serious innate heart disease. Although surgery results are generally good, some complications such as recoarctation and aortic aneurysm or persistent hypertension were serious threats to patient's health. To better understand the pathology of CoA and its underlying molecular mechanism is particularly important for early diagnosis and preventing the occurrence of its complications. However, the mechanisms of CoA remain unclear, especially for infants.

METHODS

RNA sequencing (RNA-seq) was used to identify the differentially expressed genes (DEGs) in vascular tissues of 12 patients with CoA and 10 normal participants form 3- to 34-month-old infants. The characteristic of DEGs were validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunochemical staining (IHC) in vessels of patients with CoA and normal infants.

RESULTS

A total of 2491 DEGs with the false discovery rate less than 0.05(> 1.5-fold, P < 0.05 change) were identified, including 443 upregulated genes and 2048 downregulated genes. The Gene Ontology enrichment analysis showed that 26 out of the 2491 DEGs identified were associated with cardiovascular diseases. These 26 genes were mainly associated with extracellular matrix (ECM) and smooth muscle cells (SMCs) differentiation. Three DEGs, that is, CNN1 (calponin), α-actinin1 and myosin heavy chain 11 MYH11, were validated using qRT-PCR and Western blot analysis. In addition, immunochemical staining showed that calponin and MYH11 were highly expressed on the surface and in the deep layers of the thickened intima respectively.

CONCLUSION

This study comprehensively characterized the CoA transcriptome. Migration of extracellular matrix (ECM) and smooth muscle cells (SMCs) to the subendothelial space may be the major characteristic of CoA in infants.

Extracellular matrix-mediated remodeling and mechanotransduction in large vessels during development and disease

The vascular extracellular matrix (ECM) is synthesized and secreted during embryogenesis and facilitates the growth and remodeling of large vessels. Proper interactions between the ECM and vascular cells are pivotal for building the vasculature required for postnatal dynamic circulation. The ECM serves as a structural component by maintaining the integrity of the vessel wall while also regulating intercellular signaling, which involves cytokines and growth factors. The major ECM component in large vessels is elastic fibers, which include elastin and microfibrils. Elastin is predominantly synthesized by vascular smooth muscle cells (SMCs) and uses microfibrils as a scaffold to lay down and assemble cross-linked elastin. The absence of elastin causes developmental defects that result in the subendothelial proliferation of SMCs and inward remodeling of the vessel wall. Notably, elastic fiber formation is attenuated in the ductus arteriosus and umbilical arteries. These two vessels function during embryogenesis and close after birth via cellular proliferation, migration, and matrix accumulation. In dynamic postnatal mechano-environments, the elastic fibers in large vessels also serve an essential role in proper signal transduction as a component of elastin-contractile units. Disrupted mechanotransduction in SMCs leads to pathological conditions such as aortic aneurysms that exhibit outward remodeling. This review discusses the importance of the ECM-mainly the elastic fiber matrix-in large vessels during developmental remodeling and under pathological conditions. By dissecting the role of the ECM in large vessels, we aim to provide insights into the role of ECM-mediated signal transduction that can provide a basis for seeking new targets for intervention in vascular diseases.

A "holistic" sonographic view on congenital heart disease: How automatic reconstruction using fetal intelligent navigation echocardiography eases unveiling of abnormal cardiac anatomy part II-Left heart anomalies

Volume ultrasound has been shown to provide valid complementary information on fetal anatomy. Four-dimensional assessment (4D) of the fetal cardiovascular system using spatial-temporal image correlation (STIC) allows for detailed examination of a highly complex organ from the early second trimester onward. There is compelling evidence that this technique harbors quite a number of diagnostic opportunities, but manual navigation through STIC volume datasets is highly operator dependent. In fact, STIC is not incorporated yet into daily practice. Application of the novel fetal intelligent navigation echocardiography (FINE) considerably simplifies fetal cardiac volumetric examinations. This automatic technique applied on cardiac volume datasets reportedly has both high sensitivity and specificity for the detection of congenital heart defects (CHDs). Part I reviewed current data regarding detection rates of CHDs and illustrated the additional value of an automatic approach in delineating cardiac anatomy exemplified by congenital lesions of the right heart. In part II of this pictorial essay, we focused on left heart anomalies and aimed to tabulate recent findings on the quantification of normal and abnormal cardiac anatomy.

Evaluation of Ductal Tissue in Coarctation of the Aorta Using X-Ray Phase-Contrast Tomography

We assessed the histological accuracy of X-ray phase-contrast tomography (XPCT) and investigated three-dimensional (3D) ductal tissue distribution in coarctation of the aorta (CoA) specimens. We used nine CoA samples, including the aortic isthmus, ductus arteriosus (DA), and their confluences. 3D images were obtained using XPCT. After scanning, the samples were histologically evaluated using elastica van Gieson (EVG) staining and transcription factor AP-2 beta (TFAP2B) immunostaining. XPCT sectional images clearly depicted ductal tissue distribution as low-density areas. In comparison with EVG staining, the mass density of the aortic wall positively correlated with elastic fiber formation (R = 0.69, P < 0.001). TFAP2B expression was consistent with low-density area including intimal thickness on XPCT images. On 3D imaging, the distances from the DA insertion to the distal terminal of the ductal media and to the intima on the ductal side were 1.63 ± 0.22 mm and 2.70 ± 0.55 mm, respectively. In the short-axis view, the posterior extension of the ductal tissue into the aortic lumen was 79 ± 18% of the diameter of the descending aorta. In three specimens, the aortic wall was entirely occupied by ductal tissue. The ductal intima spread more distally and laterally than the ductal media. The contrast resolution of XPCT images was comparable to that of histological assessment. Based on the 3D images, we conclude that complete resection of intimal thickness, including the opposite side of the DA insertion, is required to eliminate residual ductal tissue and to prevent postoperative re-coarctation.

Role of Extracellular Matrix in Pathophysiology of Patent Ductus Arteriosus: Emphasis on Vascular Remodeling

The ductus arteriosus (DA) is a shunt vessel between the aorta and the pulmonary artery during the fetal period that is essential for the normal development of the fetus. Complete closure usually occurs after birth but the vessel might remain open in certain infants, as patent ductus arteriosus (PDA), causing morbidity or mortality. The mechanism of DA closure is a complex process involving an orchestration of cell-matrix interaction between smooth muscle cells (SMC), endothelial cells, and extracellular matrix (ECM). ECM is defined as the noncellular component secreted by cells that consists of macromolecules such as elastin, collagens, proteoglycan, hyaluronan, and noncollagenous glycoproteins. In addition to its role as a physical scaffold, ECM mediates diverse signaling that is critical in development, maintenance, and repair in the cardiovascular system. In this review, we aim to outline the current understandings of ECM and its role in the pathophysiology of PDA, with emphasis on DA remodeling and highlight future outlooks. The molecular diversity and plasticity of ECM present a rich array of potential therapeutic targets for the management of PDA.

Pulmonary ductal coarctation and left pulmonary artery interruption; pathology and role of neural crest and second heart field during development

Objectives

In congenital heart malformations with pulmonary stenosis to atresia an abnormal lateral ductus arteriosus to left pulmonary artery connection can lead to a localised narrowing (pulmonary ductal coarctation) or even interruption We investigated embryonic remodelling and pathogenesis of this area.

Material and methods

Normal development was studied in WntCre reporter mice (E10.0–12.5) for neural crest cells and Nkx2.5 immunostaining for second heart field cells. Data were compared to stage matched human embryos and a VEGF120/120 mutant mouse strain developing pulmonary atresia.

Results

Normal mouse and human embryos showed that the mid-pharyngeal endothelial plexus, connected side-ways to the 6^th pharyngeal arch artery. The ventral segment formed the proximal pulmonary artery. The dorsal segment (future DA) was solely surrounded by neural crest cells. The ventral segment had a dual outer lining with neural crest and second heart field cells, while the distal pulmonary artery was covered by none of these cells. The asymmetric contribution of second heart field to the future pulmonary trunk on the left side of the aortic sac (so-called pulmonary push) was evident. The ventral segment became incorporated into the pulmonary trunk leading to a separate connection of the left and right pulmonary arteries. The VEGF120/120 embryos showed a stunted pulmonary push and a variety of vascular anomalies.

Summary

Side-way connection of the DA to the left pulmonary artery is a congenital anomaly. The primary problem is a stunted development of the pulmonary push leading to pulmonary stenosis/atresia and a subsequent lack of proper incorporation of the ventral segment into the aortic sac. Clinically, the aberrant smooth muscle tissue of the ductus arteriosus should be addressed to prohibit development of severe pulmonary ductal coarctation or even interruption of the left pulmonary artery.

Asparagine-linked glycosylation modifies voltage-dependent gating properties of CaV3.1-T-type Ca2+ channel

T-type channels are low-voltage-activated channels that play a role in the cardiovascular system particularly for pacemaker activity. Glycosylation is one of the most prevalent post-translational modifications in protein. Among various glycosylation types, the most common one is asparagine-linked (N-linked) glycosylation. The aim of this study was to elucidate the roles of N-linked glycosylation for the gating properties of the CaV3.1-T-type Ca2+ channel. N-linked glycosylation synthesis inhibitor tunicamycin causes a reduction of CaV3.1-T-type Ca2+ channel current (CaV3.1-ICa.T) when applied for 12 h or longer. Tunicamycin (24 h) significantly shifted the activation curve to the depolarization potentials, whereas the steady-state inactivation curve was unaffected. Use-dependent inactivation of CaV3.1-ICa.T was accelerated, and recovery from inactivation was prolonged by tunicamycin (24 h). CaV3.1-ICa.T was insensitive to a glycosidase PNGase F when the channels were expressed on the plasma membrane. These findings suggest that N-glycosylation contributes not only to the cell surface expression of the CaV3.1-T-type Ca2+ channel but to the regulation of the gating properties of the channel when the channel proteins were processed during the folding and trafficking steps in the cell.

Tissue-type plasminogen activator contributes to remodeling of the rat ductus arteriosus

AIMS

The ductus arteriosus (DA) closes after birth to adapt to the robust changes in hemodynamics, which require intimal thickening (IT) to occur. The smooth muscle cells of the DA have been reported to play important roles in IT formation. However, the roles of the endothelial cells (ECs) have not been fully investigated. We herein focused on tissue-type plasminogen activator (t-PA), which is a DA EC dominant gene, and investigated its contribution to IT formation in the DA.

METHODS AND RESULTS

ECs from the DA and aorta were isolated from fetal rats using fluorescence-activated cell sorting. RT-PCR showed that the t-PA mRNA expression level was 2.7-fold higher in DA ECs than in aortic ECs from full-term rat fetuses (gestational day 21). A strong immunoreaction for t-PA was detected in pre-term and full-term rat DA ECs. t-PA-mediated plasminogen-plasmin conversion activates gelatinase matrix metalloproteinases (MMPs). Gelatin zymography revealed that plasminogen supplementation significantly promoted activation of the elastolytic enzyme MMP-2 in rat DA ECs. In situ zymography demonstrated that marked gelatinase activity was observed at the site of disruption in the internal elastic laminae (IEL) in full-term rat DA. In a three-dimensional vascular model, EC-mediated plasminogen-plasmin conversion augmented the IEL disruption. In vivo administration of plasminogen to pre-term rat fetuses (gestational day 19), in which IT is poorly formed, promoted IEL disruption accompanied by gelatinase activation and enhanced IT formation in the DA. Additionally, experiments using five human DA tissues demonstrated that the t-PA expression level was 3.7-fold higher in the IT area than in the tunica media. t-PA protein expression and gelatinase activity were also detected in the IT area of the human DAs.

CONCLUSION

t-PA expressed in ECs may help to form IT of the DA via activation of MMP-2 and disruption of IEL.

Attenuation of ductus arteriosus intimal thickening in preterm sheep twins compared with singletons

Preterm twins have a higher morbidity rate of patent ductus arteriosus (PDA) than do singletons. However, the effect of multiple births on maturation of the ductus arteriosus (DA) has not been reported. Because intimal thickening (IT) is required for DA anatomical closure, we examined IT development in the DA of preterm twins and singletons. Sheep DA tissues obtained from preterm fetuses were subjected to elastica van Gieson staining to evaluate IT. The total IT score in each DA was the sum of the IT scores obtained from six evenly divided parts of the DA, which was positively correlated with gestational ages in singletons. Total IT scores were smaller in preterm twins than in singletons, although no difference in gestational age, birth weight, or gender ratio was observed. These data suggest that IT development of the DA is attenuated in sheep preterm twins, which may affect the higher morbidity of PDA.

Modeling of coarctation of aorta in human fetuses using 3D/4D fetal echocardiography and computational fluid dynamics

OBJECTIVES

We sought to develop a hemodynamic model of aortic and ductal arches using computational fluid dynamics (CFD) and 3D/4D spatio-temporal image correlation (STIC) fetal echocardiography and to investigate the hemodynamics of coarctation of aorta (CoA) in human fetuses using this approach.

METHODS

We obtained 3D/4D STIC fetal echocardiographic images of the aortic and ductal arches (DA) in five normal fetuses. Based on these images, we simulated the hemodynamics in the two arches using CFD. Subsequently, we reduced the dimensions of aortic isthmus from 100% to 85%, 70%, 55%, 40%, and 25% of the original dimension digitally. Numerical simulation was repeated in each condition, and flow profile, velocity, pressure, and wall shear stress (WSS) were compared with those of the baseline normal aortic and ductal arches.

RESULTS

With the progressive narrowing in the aortic isthmus, there were alterations in the flow profile, velocity, pressure, and WSS. The downstream vortexes disappeared, and the double helix profile became single helix. When the aortic isthmus reduced by 55% in dimension, there was an exponential increase in velocity and WSS and decrease in pressure.

CONCLUSIONS

The aortic and ductal arch geometry and flow lead to the alterations in flow profile, velocity, pressure, and WSS in the aortic isthmus in normal and CoA models, which are conductive of ductal issue migration into these areas. A 55% reduction in the dimension of aortic isthmus is associated with exponential change in velocity, pressure, and WSS, a probable threshold for hemodynamically significant CoA.