Atrioventricular septal defect: From embryonic development to long-term follow-up

Complete atrioventricular canal in a dog-sounds like a final judgment but is it actually one? A case report

Congenital heart disease (CHD) is an important subset of all cardiovascular diseases in dogs. Among them, there are a number of other less commonly described congenital malformations. One of these is the atrioventricular canal, which involves a defect that has several phenotypes. This report details a case of a complete atrioventricular canal (cAVC) defect. Using Rastelli's classification scheme, the diagnosis of a type-A cAVC defect was based on two-dimensional, contrast, and color Doppler echocardiography. Despite a severe defect that resulted in the atypical anatomy of the atrioventricular apparatus, as well as significant hemodynamic changes in the heart, the affected dog remained asymptomatic throughout the 48-month follow-up period. Due to its stable clinical condition, the decision was made not to begin pharmacological therapy. As this defect is rare in dogs, there are limited data in the literature on this condition. Therefore, in clinical practice, the management and monitoring of the patient may pose difficulties. Due to such limited data, it can be very difficult to provide a prognosis. For the above reasons, we hope that the following case will contribute valuable information for the monitoring of this kind of CHD.

Twin atrioventricular nodes and accessory pathways in congenital heart diseases with abnormal atrioventricular connections: Association with the developmental hierarchy of cardiac morphology

BACKGROUND

Twin atrioventricular (AV) nodes (TWAVNs) are common in heterotaxy syndrome.

OBJECTIVE

The purpose of this study was to investigate the presence and implications of TWAVNs and accessory pathways in congenital heart diseases (CHDs) with abnormal AV connections.

METHODS

A retrospective study of a 1980-2022 cohort with sufficient electrocardiographic (ECG) data for review was conducted.

RESULTS

We enrolled 136 patients with heterotaxy syndrome, 70 with congenitally corrected transposition of the great arteries (ccTGA) (4 with Ebstein anomaly), 47 with double-inlet ventricle (DIV), and 63 with isolated AV canal defect. TWAVNs, detected in the same ECG (18%), in separate ECGs (70.8%), or after electrophysiological study (11.2%), were present in 43.4% of heterotaxy, 10.6% of DIV, 10% of ccTGA, and 1.6% of AV canal defect cases. Accessory pathways were noted in 11.4% of ccTGA and 4.4% of heterotaxy cases, but none of the DIV and AV canal cases. Actuarial incidence of supraventricular tachycardia (SVT) by age 10 was 0.354, 0.121, 0.022, and 0 in heterotaxy, ccTGA, DIV, and AV canal, respectively. In patients with TWAVNs, the risk of SVT varies according to the rate of TWAVNs in each CHD type, with risks of 65.5%, 58.3%, and 0% for TWAVNs rates >50%, 10%-50%, and <10%, respectively. Onset age of tachycardia did not differ between those with TWAVNs and those with accessory pathways.

CONCLUSION

In CHD with abnormal AV connections, evidence suggested a developmental hierarchy in the propensity to exhibit TWAVNs, but not for accessory pathways. The earlier cardiac developmental errors occur, the higher the likelihood of TWAVNs and the greater the chance of SVT.

Diagnosis and surgical treatment for complete atrioventricular septal defect with intact atrial septum

A six-month-old boy with Down syndrome, complete atrioventricular septal defect with intact atrial septum, and moderate left-sided atrioventricular valve regurgitation underwent surgery. The presence of a common atrioventricular junction could not be diagnosed preoperatively. Postoperative left-sided atrioventricular valve regurgitation remained mild by complete cleft closure, direct closure of incised atrial septum, and patch augmentation of the underside of septum primum.

Impact of Age and of the Patent Ductus Arteriosus on Pulmonary Hemodynamics in Children with Complete Atrioventricular Septal Defect

Complete atrioventricular septal defect (CAVSD) can lead to the development of pulmonary obstructive vascular disease due to high pulmonary blood flow and pressures. This study aimed to evaluate the changes in pulmonary hemodynamics with aging and with patent ductus arteriosus (PDA) in children with CAVSD. We retrospectively evaluated 137 children (94% with trisomy 21, median age of 195 (25-2963) days, 58.4% female) with CASVD referred to cardiac catheterization from January 2000 to December 2020. Those with associated congenital heart disease, except PDA, had been excluded. They were divided into three age terciles (T1, T2, and T3). Aging was directly associated with higher mean (T1: 34.2 ± 9.1; T2: 37.1 ± 5.8; T3: 42 ± 10.6 mmHg, p < 0.001) and diastolic (T1: 19.4 ± 5.3; T2 21.6 ± 5.0; T3: 26.0 ± 9.5 mmHg, P < 0.001) pulmonary arterial pressures, and with higher pulmonary vascular resistance (T1: 3.24 ± 1.69, T2: 3.47 ± 1.19; T3: 4.49 ± 3.91 Wu.m2, p = 0.023). This resulted in a loss of eligibility for anatomical correction, which became evident only after 300 days of age. PDA was associated with a higher mean (37.2 [35.9; 38.5] vs. 41.3 [37.5; 45.0] mmHg, p = 0.049) and diastolic (21.7 [20.7; 22.6] vs. 26.4 [24.1; 29.0] mmHg, p = 0.001) pulmonary pressure, and resistor-compliance time (0.28 [0.26; 0.29] vs. 0.36 [0.31; 0.40], p = 0.001) after adjusting for age and sex. In children with CAVSD, aging was associated with worsening of pulmonary vascular hemodynamics, particularly when PDA was associated, resulting in loss of eligibility for anatomical correction after 10 months of age as the first surgical option.

Double outlet right atrium in a dog

Double outlet right atrium is a rare congenital cardiac abnormality that has been previously reported in humans and cats, but not in dogs. A double outlet right atrium is typically characterized by the presence of a leftward deviation of the interatrial septum and atrial septal defect. Therefore, the right atrium drains into both ventricles. The unique features consistent with double outlet right atrium were identified by transthoracic echocardiography and computed tomography in a puppy. This case report describes the clinical, echocardiographic, and tomographic findings of a five-month-old Cocker Spaniel diagnosed with this rare congenital abnormality.

Effect of deletion of the protein kinase PRKD1 on development of the mouse embryonic heart

Congenital heart disease (CHD) is the most common congenital anomaly, with an overall incidence of approximately 1% in the United Kingdom. Exome sequencing in large CHD cohorts has been performed to provide insights into the genetic aetiology of CHD. This includes a study of 1891 probands by our group in collaboration with others, which identified three novel genes-CDK13, PRKD1, and CHD4, in patients with syndromic CHD. PRKD1 encodes a serine/threonine protein kinase, which is important in a variety of fundamental cellular functions. Individuals with a heterozygous mutation in PRKD1 may have facial dysmorphism, ectodermal dysplasia and may have CHDs such as pulmonary stenosis, atrioventricular septal defects, coarctation of the aorta and bicuspid aortic valve. To obtain a greater appreciation for the role that this essential protein kinase plays in cardiogenesis and CHD, we have analysed a Prkd1 transgenic mouse model (Prkd1em1) carrying deletion of exon 2, causing loss of function. High-resolution episcopic microscopy affords detailed morphological 3D analysis of the developing heart and provides evidence for an essential role of Prkd1 in both normal cardiac development and CHD. We show that homozygous deletion of Prkd1 is associated with complex forms of CHD such as atrioventricular septal defects, and bicuspid aortic and pulmonary valves, and is lethal. Even in heterozygotes, cardiac differences occur. However, given that 97% of Prkd1 heterozygous mice display normal heart development, it is likely that one normal allele is sufficient, with the defects seen most likely to represent sporadic events. Moreover, mRNA and protein expression levels were investigated by RT-qPCR and western immunoblotting, respectively. A significant reduction in Prkd1 mRNA levels was seen in homozygotes, but not heterozygotes, compared to WT littermates. While a trend towards lower PRKD1 protein expression was seen in the heterozygotes, the difference was only significant in the homozygotes. There was no compensation by the related Prkd2 and Prkd3 at transcript level, as evidenced by RT-qPCR. Overall, we demonstrate a vital role of Prkd1 in heart development and the aetiology of CHD.

Revisiting Atrioventricular Septal Defects: Exploring Chromosomal Abnormalities, Cardiac and Extracardiac Anomalies in a Contemporary Prenatal Cohort

To estimate if there is an association between partial AVSD with chromosomal abnormalities, cardiac and extracardiac malformations, and to report the outcomes of prenatally diagnosed AVSD in a large, contemporary cohort. This is a retrospective cohort study of 190 prenatally diagnosed fetal AVSD between 2014 and 2023. Type of AVSD (complete vs partial), additional cardiac findings, extracardiac findings, presence of a heterotaxy, results of prenatal karyotype, and pregnancy outcomes were documented and analyzed. A total of 190 cases of fetal AVSD were analyzed. Complete AVSDs comprised 141 (74.2%) of the cohort, while partial AVSDs comprised 49 (25.7%). Karyotype was completed in 131 cases, and in 98 (74.8%) cases chromosomal abnormalities were identified, with trisomy 21 being the most common (53/131, 40.5%). Complete AVSDs were associated with trisomy 21 (45.5%, p = 0.04), Isolated cases of complete AVSDs (p = 0.03). Partial AVSDs were associated with trisomy 18 (53.1%, p < 0.001). In cases of partial AVSDs with aneuploidies, 7 (70%) had an ostium primum defect and 20 (90.9%) of AV canal type VSD. Isolated partial AVSD had no clear association with aneuploidies. There were additional cardiac anomalies in 96 (50.5%) and extracardiac anomalies in 134 (70.5%) of the cohort. There were no differences between partial and complete AVSD in rate of additional cardiac and extracardiac anomalies. AVSD was part of a heterotaxy in 47 (24.7%) of cases, and heterotaxy was associated with complete AVSD in the majority of cases (43/47, 91.4%, p = 0.003). Fetal partial AVSDs are associated with trisomy 18. Fetal complete AVSDs, even isolated, are associated with trisomy 21. There were no differences in association of other aneuploidies, additional cardiac findings, or extracardiac anomalies between prenatally diagnosed complete AVSDs and partial AVSDs.

Efficacy of atrioventricular valve regurgitation in the first trimester for the diagnosis of atrioventricular septal defect

PURPOSE

To investigate the efficacy of atrioventricular valve regurgitation (AVVR) for predicting atrioventricular septal defect (AVSD) in the first trimester.

METHODS

We performed a prospective observational study, screening for complicated congenital heart diseases and AVVR in fetuses at 11 to 13+6 weeks of gestation by advanced dynamic flow in four-chamber view and three-vessel-trachea view.

RESULTS

43 549 fetuses at 11 to 13+6 weeks of gestation were screened by echocardiography, of which 37 cases were diagnosed with AVSD, including complete AVSD (31 cases), intermediate AVSD (3 cases) and partial AVSD (1 cases), undiagnosed intermediate AVSD (2 cases), and misdiagnosed case (2 cases). AVVR was observed in 34 cases (34/37) in the first trimester, 59. 46% (22/37) nuchal translucency greater than 95th percentile, 29. 73% (11/37) absence of nasal bone, 32. 43% (12/37) ductus venosus A wave inversion, and 40. 54% (15/37) had tricuspid regurgitation. The sensitivity of common AVVR in predicting AVSD is better than other ultrasonic indexes.

CONCLUSIONS

AVVR can be used as an ultrasonic indicator to predict AVSD in the first trimester, which is beneficial to detect AVSD.

Hemodynamic Melody of Postnatal Cardiac and Pulmonary Development in Children with Congenital Heart Diseases

Hemodynamics is the eternal theme of the circulatory system. Abnormal hemodynamics and cardiac and pulmonary development intertwine to form the most important features of children with congenital heart diseases (CHDs), thus determining these children's long-term quality of life. Here, we review the varieties of hemodynamic abnormalities that exist in children with CHDs, the recently developed neonatal rodent models of CHDs, and the inspirations these models have brought us in the areas of cardiomyocyte proliferation and maturation, as well as in alveolar development. Furthermore, current limitations, future directions, and clinical decision making based on these inspirations are highlighted. Understanding how CHD-associated hemodynamic scenarios shape postnatal heart and lung development may provide a novel path to improving the long-term quality of life of children with CHDs, transplantation of stem cell-derived cardiomyocytes, and cardiac regeneration.

Thymic Atrophy and Immune Dysregulation in Infants with Complex Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, and up to 50% of infants with CHD require cardiovascular surgery early in life. Current clinical practice often involves thymus resection during cardiac surgery, detrimentally affecting T-cell immunity. However, epidemiological data indicate that CHD patients face an elevated risk for infections and immune-mediated diseases, independent of thymectomy. Hence, we examined whether the cardiac defect impacts thymus function in individuals with CHD. We investigated thymocyte development in 58 infants categorized by CHD complexity. To assess the relationship between CHD complexity and thymic function, we analyzed T-cell development, thymic output, and biomarkers linked to cardiac defects, stress, or inflammation. Patients with highly complex CHD exhibit thymic atrophy, resulting in low frequencies of recent thymic emigrants in peripheral blood, even prior to thymectomy. Elevated plasma cortisol levels were detected in all CHD patients, while high NT-proBNP and IL-6 levels were associated with thymic atrophy. Our findings reveal an association between complex CHD and thymic atrophy, resulting in reduced thymic output. Consequently, thymus preservation during cardiovascular surgery could significantly enhance immune function and the long-term health of CHD patients.

Hippo Signaling Mediates TGFβ-Dependent Transcriptional Inputs in Cardiac Cushion Mesenchymal Cells to Regulate Extracellular Matrix Remodeling

The transforming growth factor beta (TGFβ) and Hippo signaling pathways are evolutionarily conserved pathways that play a critical role in cardiac fibroblasts during embryonic development, tissue repair, and fibrosis. TGFβ signaling and Hippo signaling are also important for cardiac cushion remodeling and septation during embryonic development. Loss of TGFβ2 in mice causes cardiac cushion remodeling defects resulting in congenital heart disease. In this study, we used in vitro molecular and pharmacologic approaches in the cushion mesenchymal cell line (tsA58-AVM) and investigated if the Hippo pathway acts as a mediator of TGFβ2 signaling. Immunofluorescence staining showed that TGFβ2 induced nuclear translocation of activated SMAD3 in the cushion mesenchymal cells. In addition, the results indicate increased nuclear localization of Yes-associated protein 1 (YAP1) following a similar treatment of TGFβ2. In collagen lattice formation assays, the TGFβ2 treatment of cushion cells resulted in an enhanced collagen contraction compared to the untreated cushion cells. Interestingly, verteporfin, a YAP1 inhibitor, significantly blocked the ability of cushion cells to contract collagen gel in the absence or presence of exogenously added TGFβ2. To confirm the molecular mechanisms of the verteporfin-induced inhibition of TGFβ2-dependent extracellular matrix (ECM) reorganization, we performed a gene expression analysis of key mesenchymal genes involved in ECM remodeling in heart development and disease. Our results confirm that verteporfin significantly decreased the expression of α-smooth muscle actin (Acta2), collagen 1a1 (Col1a1), Ccn1 (i.e., Cyr61), and Ccn2 (i.e., Ctgf). Western blot analysis indicated that verteporfin treatment significantly blocked the TGFβ2-induced activation of SMAD2/3 in cushion mesenchymal cells. Collectively, these results indicate that TGFβ2 regulation of cushion mesenchymal cell behavior and ECM remodeling is mediated by YAP1. Thus, the TGFβ2 and Hippo pathway integration represents an important step in understanding the etiology of congenital heart disease.

Maternal Pre-Existing Diabetes: A Non-Inherited Risk Factor for Congenital Cardiopathies

Congenital heart defects (CHDs) are the most common form of birth defects in humans. They occur in 9 out of 1000 live births and are defined as structural abnormalities of the heart. Understanding CHDs is difficult due to the heterogeneity of the disease and its multifactorial etiology. Advances in genomic sequencing have made it possible to identify the genetic factors involved in CHDs. However, genetic origins have only been found in a minority of CHD cases, suggesting the contribution of non-inherited (environmental) risk factors to the etiology of CHDs. Maternal pregestational diabetes is associated with a three- to five-fold increased risk of congenital cardiopathies, but the underlying molecular mechanisms are incompletely understood. According to current hypotheses, hyperglycemia is the main teratogenic agent in diabetic pregnancies. It is thought to induce cell damage, directly through genetic and epigenetic dysregulations and/or indirectly through production of reactive oxygen species (ROS). The purpose of this review is to summarize key findings on the molecular mechanisms altered in cardiac development during exposure to hyperglycemic conditions in utero. It also presents the various in vivo and in vitro techniques used to experimentally model pregestational diabetes. Finally, new approaches are suggested to broaden our understanding of the subject and develop new prevention strategies.

Outcome of Down patients with repaired versus unrepaired atrioventricular septal defect

Background and aims

Patients with Down Syndrome (DS) are frequently born with an atrioventricular septal defect (AVSD). Surgical repair of the defect aims to minimize mortality and morbidity. However, a surgical intervention, specifically in DS patients, is not without risk and a subgroup of patients underwent only conservative non-surgical treatment. Outcome data of these different approaches are scarce. The aim of this retrospective study was to compare the long-term outcome of DS patients with and without surgery for AVSD.

Methods

DS patients registered with AVSD in the hospital's database from January 1980 till December 2020 were selected. Patient characteristics, peri-operative if appropriate, and follow-up data were obtained from the medical files.

Results

In total, 72 unrepaired (36 male, 50%) and 134 repaired patients (61 male, 46%) were included. After a maximum of 60 years of follow-up, the all-cause mortality was 45.8% and 17.1%, respectively. Thirty-six percent and 13%, respectively, were labeled as non-cardiovascular death. Mean survival time for unrepaired AVSD was 40.7 years (95% CI 36.1-45.2) and for repaired AVSD 38.5 years (95% CI 35.3-41.6) (Log rank p = 0.465). However, the survival rate 35 years after birth was 62.1% for unrepaired patients versus 81.7% for repaired patients. Mortality rates were the highest the first months after surgical repair.

Conclusions

The mean survival rate of Down patients, born with an AVSD, did not differ between repair or not. However, long-term survival rate was higher in patients who underwent surgical repair. Mortality was highest the first months after surgery.

The V-shaped double-layer patch technique for complete atrioventricular septal defect: A novel surgical technique

OBJECTIVE

Several surgical techniques for repair of a complete atrioventricular septal defect have been developed. However, the postoperative complications with these methods may lead to reoperation during follow-up. The aim of this report is to share our experience with a modified surgical technique for complete atrioventricular septal defect that has anatomic advantages postoperatively and could reduce the reoperation rate.

METHODS

Twenty-nine patients who underwent repair of complete atrioventricular septal defect using a V-shaped double-layer patch between April 2011 and September 2019 were retrospectively investigated.

RESULTS

There were no deaths (0%) and only 1 reoperation (3.4%) in the series. The aortic crossclamp and cardiopulmonary bypass times were 62.7 ± 16.0 minutes and 113.9 ± 25.9 minutes, respectively. The median follow-up duration was 5.1 years. To date, no significant residual ventricular septal defects have been detected and no left ventricular outflow tract obstruction has been seen on echocardiography in any patient. During follow-up, the left atrioventricular valve status was assessed as no incompetence in 9 patients (31.0%), trivial in 18 patients (62.1%), and mild in 2 patients (6.9%).

CONCLUSIONS

The V-shaped double-layer patch technique is a valuable surgical option for patients with complete atrioventricular septal defects. The midterm results in our series document excellent performance of this technique, which augments the area of the anterior valve of the left atrioventricular valve to make it closer to a normal mitral valve and may also reduce the need for reoperation.

Rare copy number variation analysis identifies disease-related variants in atrioventricular septal defect patients

Atrioventricular septal defect (AVSD) is a deleterious subtype of congenital heart diseases (CHD) characterized by atrioventricular canal defect. The pathogenic genetic changes of AVSD remain elusive, particularly for copy number variation (CNV), a large segment variation of the genome, which is one of the major forms of genetic variants resulting in congenital heart diseases. In the present study, we recruited 150 AVSD cases and 100 healthy subjects as controls for whole exome sequencing (WES). We identified total 4255 rare CNVs using exon Hidden Markov model (XHMM) and screened rare CNVs by eliminating common CNVs based on controls and Database of Genomic Variants (DGV). Each patient contained at least 9 CNVs, and the CNV burden was prominently presented in chromosomes 19,22,21&16. Small CNVs (<500 kb) were frequently observed. By leveraging gene-based burden test, we further identified 20 candidate AVSD-risk genes. Among them, DYRK1A, OBSCN and TTN were presented in the core disease network of CHD and highly and dynamically expressed in the heart during the development, which indicated they possessed the high potency to be AVSD-susceptible genes. These findings not only provided a roadmap for finally unveiling the genetic cause of AVSD, but also provided more resources and proofs for clinical genetics.

Sox9 Expression in the Second Heart Field; A Morphological Assessment of the Importance to Cardiac Development with Emphasis on Atrioventricular Septation

Failure to form the septal structures that separate the left and right cardiac chambers results in defects that allow shunting of blood from one side of the heart to the other, leading to the mixing of oxygenated and de-oxygenated blood. The atrioventricular (AV) mesenchymal complex, consisting of the AV cushions, the Dorsal Mesenchymal Protrusion (DMP), and the mesenchymal cap, plays a crucial role in AV septation. Cells found in these structures derive from different cell lineages. In this study we have investigated the role of the transcription factor Sox9 in the Second Heart Field (SHF) with the emphasis on the formation of the atrioventricular septal complex. Using a mouse model in which Sox9 is conditionally deleted from the SHF we demonstrate that in this model virtually all mouse embryos develop septal abnormalities, including complete atrioventricular septal defects (cAVSDs) and isolated ventricular septal defects. Our morphological analyses indicate that perturbation of the development of the mesenchymal cap appears to play a crucial role in the pathogenesis of the atrial septal defects observed in the AVSDs and suggests that this component of the AV mesenchymal complex might play a more important role in AV septation than previously appreciated.

Familial partial atrioventricular septal defect in four related kindreds: case series and review of the literature

Background

Atrioventricular septal defects are common congenital heart defects and comprise a spectrum of anomalies, these defects were described in few pedigrees suggesting a familial pattern of inheritance, and they are more common in patients with chromosomal abnormalities. The familial occurrence of this particular type of congenital heart disease is uncommon and few cases have been identified as partial atrioventricular septal defect in adults apart from other chromosomal abnormalities.

Case presentation

We report four cases of adult females who were diagnosed with partial atrioventricular septal defect in four related families, our patients do not have the morphology of Down syndrome.

Conclusions

Further researches on genotyping such patients might contribute to our knowledge regarding this particular cardiac malformation.

Predisposition to atrioventricular septal defects may be caused by SOX7 variants that impair interaction with GATA4

Atrioventricular septal defects (AVSD) are a complicated subtype of congenital heart defects for which the genetic basis is poorly understood. Many studies have demonstrated that the transcription factor SOX7 plays a pivotal role in cardiovascular development. However, whether SOX7 single nucleotide variants are involved in AVSD pathogenesis is unclear. To explore the potential pathogenic role of SOX7 variants, we recruited a total of 100 sporadic non-syndromic AVSD Chinese Han patients and screened SOX7 variants in the patient cohort by targeted sequencing. Functional assays were performed to evaluate pathogenicity of nonsynonymous variants of SOX7. We identified three rare SOX7 variants, c.40C > G, c.542G > A, and c.743C > T, in the patient cohort, all of which were found to be highly conserved in mammals. Compared to the wild type, these SOX7 variants had increased mRNA expression and decreased protein expression. In developing hearts, SOX7 and GATA4 were highly expressed in the region of atrioventricular cushions. Moreover, SOX7 overexpression promoted the expression of GATA4 in human umbilical vein endothelial cells. A chromatin immunoprecipitation assay revealed that SOX7 could directly bind to the GATA4 promoter and luciferase assays demonstrated that SOX7 activated the GATA4 promoter. The SOX7 variants had impaired transcriptional activity relative to wild-type SOX7. Furthermore, the SOX7 variants altered the ability of GATA4 to regulate its target genes. In conclusion, our findings showed that deleterious SOX7 variants potentially contribute to human AVSD by impairing its interaction with GATA4. This study provides novel insights into the etiology of AVSD and contributes new strategies to the prenatal diagnosis of AVSD.

Common Atrium or Atrioventricular Septal Defect: What Is in a Name?

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Common atrium is characterized by complete/near-complete absence of IAS.

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Common atrium frequently accompanies AVSD, although it can occur as an isolated entity.

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Most AVSDs with an atrial communication have normal to near-normal atrial septal lengths.

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Partial AVSD with near-complete absence of IAS is an uncommonly reported heart condition.

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With many echo features present, it is difficult to apply one diagnostic label to complex CHD.

Complete Atrioventricular Septal Defects after the Age of 40 Years

Background: There is an increasing number of adults with complete atrioventricular septal defects (cAVSD). However, data regarding older adults are lacking. The aim of this study is to analyze the outcome of adults with cAVSD over the age of 40 years. Methods: Patients with cAVSD who were ≥40 years of age at any point between 2005 until 2018 were included retrospectively. Data were retrieved from hospital records. The primary endpoint was a combination of death from any cause and unplanned hospitalizations due to cardiac reasons. Results: 43 patients (60.5% female, mean age 43.7 ± 6.0 years, genetic syndrome 58.1%) were included. At begin of follow-up, the majority of patients (n = 41, 95.3%) was in New York Heart Association (NYHA) class I or II. Out of the whole cohort 26 (60.5%) had undergone cardiac surgery. At baseline, at least one extracardiac comorbidity was present in 40 patients (93.0%). Median follow-up was 1.7 years (IQR 0.3–4.6). On univariate Cox analysis, NYHA class at begin of follow-up (hazard ratio: 1.96, CI 95%: 1.04–3.72, p < 0.05) was the only predictor for the primary endpoint. Conclusions: Significant morbidity and mortality is present in cAVSD patients over the age of 40 years. NYHA class is predictive for a worse outcome.

Prenatal ethanol exposure impairs the conduction delay at the atrioventricular junction in the looping heart

The etiology of ethanol-related congenital heart defects has been the focus of much study, but most research has concentrated on cellular and molecular mechanisms. We have shown with optical coherence tomography (OCT) that ethanol exposure led to increased retrograde flow and smaller atrioventricular (AV) cushions compared with controls. Since AV cushions play a role in patterning the conduction delay at the atrioventricular junction (AVJ), this study aims to investigate whether ethanol exposure alters the AVJ conduction in early looping hearts and whether this alteration is related to the decreased cushion size. Quail embryos were exposed to a single dose of ethanol at gastrulation, and Hamburger-Hamilton stage 19-20 hearts were dissected for imaging. Cardiac conduction was measured using an optical mapping microscope and we imaged the endocardial cushions using OCT. Our results showed that, compared with controls, ethanol-exposed embryos exhibited abnormally fast AVJ conduction and reduced cushion size. However, this increased conduction velocity (CV) did not strictly correlate with decreased cushion volume and thickness. By matching the CV map to the cushion-size map along the inflow heart tube, we found that the slowest conduction location was consistently at the atrial side of the AVJ, which had the thinner cushions, not at the thickest cushion location at the ventricular side as expected. Our findings reveal regional differences in the AVJ myocardium even at this early stage in heart development. These findings reveal the early steps leading to the heterogeneity and complexity of conduction at the mature AVJ, a site where arrhythmias can be initiated.NEW & NOTEWORTHY To the best of our knowledge, this is the first study investigating the impact of ethanol exposure on the early cardiac conduction system. Our results showed that ethanol-exposed embryos exhibited abnormally fast atrioventricular conduction. In addition, our findings, in CV measurements and endocardial cushion thickness, reveal regional differences in the AVJ myocardium even at this early stage in heart development, suggesting that the differentiation and maturation at this site are complex and warrant further studies.

Atrioventricular Septal Defects: Pathology, Imaging, and Treatment Options

PURPOSE OF REVIEW

Atrioventricular septal defects (AVSD) represent a broad spectrum of congenital anomalies from simple to the most complex heart defects including some distinct types. Clinical presentation and timing of intervention differ by morphological subset and functional anatomy. Herein, we review morphological variations and characteristics that determine appropriate intervention and provide insights into functional anatomy based on detailed three-dimensional (3D) assessment of AVSDs.

RECENT FINDINGS

The understanding of functional morphology of AVSDs has improved significantly with detailed 3D echocardiographic evaluation of the atrioventricular junction and valve morphology. As prenatal detection of AVSDs has increased significantly, it has become the most common fetal cardiac diagnosis enabling antenatal counseling and delivery planning. Advances in diagnosis and perioperative care have resulted in optimal outcomes. The diagnosis and management of AVSDs have improved over the years with enhanced understanding of anatomy and perioperative care resulting in optimal short and long-term outcomes.

The transcription factor Sox7 modulates endocardiac cushion formation contributed to atrioventricular septal defect through Wnt4/Bmp2 signaling

Cardiac septum malformations account for the largest proportion in congenital heart defects. The transcription factor Sox7 has critical functions in the vascular development and angiogenesis. It is unclear whether Sox7 also contributes to cardiac septation development. We identified a de novo 8p23.1 deletion with Sox7 haploinsufficiency in an atrioventricular septal defect (AVSD) patient using whole exome sequencing in 100 AVSD patients. Then, multiple Sox7 conditional loss-of-function mice models were generated to explore the role of Sox7 in atrioventricular cushion development. Sox7 deficiency mice embryos exhibited partial AVSD and impaired endothelial to mesenchymal transition (EndMT). Transcriptome analysis revealed BMP signaling pathway was significantly downregulated in Sox7 deficiency atrioventricular cushions. Mechanistically, Sox7 deficiency reduced the expressions of Bmp2 in atrioventricular canal myocardium and Wnt4 in endocardium, and Sox7 binds to Wnt4 and Bmp2 directly. Furthermore, WNT4 or BMP2 protein could partially rescue the impaired EndMT process caused by Sox7 deficiency, and inhibition of BMP2 by Noggin could attenuate the effect of WNT4 protein. In summary, our findings identify Sox7 as a novel AVSD pathogenic candidate gene, and it can regulate the EndMT involved in atrioventricular cushion morphogenesis through Wnt4-Bmp2 signaling. This study contributes new strategies to the diagnosis and treatment of congenital heart defects.

CHROMOSOMAL DISEASES IN THE HUMAN PATHOLOGY

Background. Chromosomal diseases are the cause of 45-50 % of multiple birth defects. Basic research on mutations is performed using genomic technologies to identify a correlation between genotype and phenotype in aneuploidies and to understand its pathogenesis. Objective. The aim of the research is to study the etiology, pathogenesis of symptoms and diagnostics for patients with Down, Klinefelter, Turner syndromes and double aneuploidies by 21 and sex chromosomes. Methods. A literature review by the keywords “Down syndrome”, “Klinefelter syndrome”, “Turner syndrome”, “double aneuploidy” for the period of 2000-2020 was carried out. Results. Down, Klinefelter and Turner syndromes are the most common aneuploidy among viable newborns. Frequency of meiotic non-disjunction events causing these aneuploidies increases with the age of a woman. Identified genes are responsible for pathogenesis of symptoms in trisomy 21, Turner and Klinefelter syndromes. Diagnostics of chromosomal diseases includes prenatal screening programs and postnatal testing. Conclusions. Cytogenetic variants of Down syndrome are simple complete trisomy 21, translocation form and mosaicism. Trisomy 21 is associated with advanced maternal age. Phenotypic manifestations of Down syndrome are associated with the locus 21q22. The maternal and parental nondisjunction of X-chromosomes in meiosis causes Klinefelter and Turner syndromes. These chromosomal diseases are variants of intersexualism with intermediate chromosomal sex. Down-Klinefelter and Down-Turner syndromes are double aneuploidies. Patients have a Down syndrome phenotype at birth, and signs of Klinefelter and Turner syndromes occur during puberty. Diagnosis of aneuploidy is based on the cytogenetic investigation (karyotyping), DNA analysis, ultrasonography and biochemical markers of chromosomal pathology.

Prenatal Atrioventricular Septal Defect (AVSD) as a planned congenital heart disease with different outcome depending on the presence of the coexisting extracardiac abnormalities (ECA) and/or malformations (ECM)

Introduction: Prenatal atrioventricular septal defect (AVSD) on frequent occasions coexists with other cardiac or extracardiac abnormalities or malformation which may change the prognosis and the management with the fetus and the newborn. The aim of the research was to assess the prognosis and the outcome of prenatally diagnosed AVSD based on the classification which also includes coexisting extracardiac abnormalities and malformations as well as its influence on the prenatal consultation.Methods: It was a retrospective analysis of 113 patients with prenatally diagnosed AVSD. The group was selected out of 871 patients with CHD. Out of 113 fetuses with AVSD we exclude those in whom AVSD was coexistent with other cardiac malformations (n = 41). Extracardiac abnormalities [ECA] were defined as problems which do not require surgical intervention after delivery, they were usually markers of a genetic syndrome. Extracardiac malformations [ECM] were defined as problems requiring surgical interventions after delivery or lethal malformations. All 72 fetuses with an isolated AVSD were classified to one of the three groups: (1) Simple AVSD - (sAVSD) - a fetus with isolated AVSD without coexisting ECA and ECM (n = 6), (2) sAVSD + ECA - a fetus with isolated AVSD, with coexisting ECA (n = 28), (3) sAVSD + ECM - a fetus with isolated AVSD, with coexisting ECM (n = 38).Results: The pregnancy from the groups sAVSD + ECM were, in fact, more often referred to the prenatal cardiology centers on account of the existing ECM (p=.03). There were no differences between the two subgroups in regard to: the mean age of the pregnancy, the mean age of the fetus at the time of diagnosis and during diagnostic testing at the referral center, the gender of the fetus. An increased nuchal translucency (NT) was most often found in fetuses from the group AVSD + ECA (n = 13/23), which was connected with more frequent occurrence of abnormal karyotype (p=.048). The trisomy 21 more frequently referred to pregnancy with sAVSD + ECA than those with sAVSD + ECM (p=.0006). In the group sAVSD + ECM there was the highest number of fetuses small for the gestational age detected -48.65% (p=.01). Most often premature deliveries were found in the group sAVSD + ECM (72.73%). The duration of gestation in the group sAVSD + ECM turned out to be much shorter than that in the group with the isolated sAVSD (p=.01) and sAVSD + ECA (p=.03). The lowest Apgar score was in the newborns from the group sAVSD + ECM (p=.002). Longer period of gestation was connected with the higher score on Apgar scale (R = 0.541; p=.001). The average delivery weight of the newborns was the lowest in the group sAVSD + ECM (p=.04). sAVSD + ECM was connected with the significantly higher death rate than the isolated sAVSD (p=.0047) or sAVSD + ECA (p<.00001). The fatality rate of the newborns/ fetuses from the pregnancies lasting less than 37 weeks turned out to be much higher than in the case of the remaining pregnancies (sAVSD p=.002).Conclusions: (1) The majority of fetuses with AVSD remained the patients of just obstetricians and prenatal cardiologists because of highly heterogeneous of the coexisting malformations and abnormalities and since they perish in the period of fetal or neonatal life usually they are not seen by the pediatricians or cardiac surgeons. (2) The classification of the AVSD in fetus to a particular group of the prognostic classification of the fetal heart defects helps to plan perinatal management and supplies information regarding the prognosis. (3) The highest mortality rate was in a group of AVSD + ECM, probably due to shorter time of pregnancy duration, fetuses grow restriction and low Apgar score in 1 minute of life.

Modified Single Repair Technique for Complete Atrioventricular Septal Defect: A Propensity Score Matching Analysis

There were controversies about the priority of modified single patch (MSP) technique compared with two-patch (TP) technique for patients with complete atrioventricular septal defect (CAVSD). From 2002 to 2013, patients who diagnosed as balanced CAVSD in our institution were retrospectively included. Patients with unbalanced ventricles or associated anomalies were excluded. The primary endpoint was all-cause mortality and the secondary endpoint consist of left atrioventricular dysfunction or left atrioventricular outflow tract obstruction (LVOTO). A total of 74 patients underwent MSP repair and 102 patients underwent TP repair. After 1:1 propensity matching, there were 46 Rastelli type A CAVSD patients in each group. Patients in MSP group had shorter cardiopulmonary bypass time [median (interquartile range) 73.5 (65.5-95.0) versus 105.0 (88.8-130.0) min, P < 0.001] and aortic cross-clamp time [105.5 (90.0-128.0) versus 143.0 (122.0-184.0) min, P < 0.001]. In total, the primary endpoint occurred in 12 patients, including 2/46 (4.3%) in MSP group and 10/46 (21.7%) in TP group. That 1-year, 3-year, 5-year survival rate can be calculated as 95.6%, 95.6%, 95.6% in MSP group and 92.6%, 80.4%, 78.2% in TP group, P = 0.015. No significant statistical difference found for the secondary endpoints that 7/46 (15.2%) patients occurred moderate or severe LAVVR in MSP group versus 11/46 (23.9%) patients in TP group, P = 0.293. No LVOTO occurred in both groups. Besides the simplicity of technique, MSP technique may be safer.

Modified Single-Patch versus Two-Patch Repair for Atrioventricular Septal Defect: A Systematic Review and Meta-Analysis

BACKGROUND

We performed a meta-analysis of studies to determine whether the modified single-patch technique offers benefits when compared to the two-patch repair. The postoperative outcomes examined in this study were cardiopulmonary bypass time, cross-clamp time, duration of mechanical ventilation, intensive care unit length of stay, total hospital length of stay, need for reoperation, need for reoperation for left ventricular outflow tract obstruction or left atrioventricular valve regurgitation, need for pacemaker implantation, and mortality during follow-up.

METHODS

A review was conducted to identify studies comparing a modified single-patch repair versus two-patch repair. A fixed-effects model was utilized for end points with low heterogeneity and a random-effects model for end points with significant heterogeneity. Meta-regression was also performed to determine the influence of other factors on the variables of interest.

RESULTS

A total of 964 unique manuscripts were screened, with 10 being included in the final analyses. There were a total of 724 patients, with 353 (49%) having undergone repair utilizing a modified single-patch repair. Mean age at repair for modified single-patch repair and two-patch repair was 8.81 and 9.03 months, respectively. Significant differences were noted in cardiopulmonary bypass time and cross-clamp time with mean difference of -28.53 and -22.69 minutes, respectively. In comparison to the two-patch repair, both times were decreased in modified single-patch repair. No significant difference was noted in any other variables.

CONCLUSIONS

Modified single-patch repair for atrioventricular septal defects requires less cardiopulmonary bypass and cross-clamp time but does not significantly impact the examined postoperative outcomes.

Perioperative Echocardiography in the Adult With Congenital Heart Disease

Survival of patients with congenital heart disease has significantly improved over the last 2 decades, confronting interventionalists, surgeons, anesthesiologists, cardiologists, and intensivists with often unfamiliar complex pathophysiology in the perioperative setting. Aside from cardiac catheterization, echocardiography has become the main imaging modality in the hospitalized adult with congenital heart disease. The great variety of congenital lesions and their prior surgical management challenges practitioners to generate optimal imaging, reporting, and interpretation of these complex anatomic structures. Standardization of echocardiographic studies can not only provide significant benefits in the surveillance of these patients, but also facilitate understanding of pathophysiologic mechanism and assist clinical management in the perioperative setting. Knowledge in obtaining and interpreting uniform imaging protocols is essential for the perioperative clinician. In this publication, the authors review current international consensus recommendations on echocardiographic imaging of adults with congenital heart disease and describe the fundamental components by specific lesion. The authors will emphasize key aspects pertinent to the clinical management when imaging these patients in the perioperative setting. The goal of this review is to familiarize the perioperative physician on how to structure and standardize echocardiographic image acquisition of congenital heart disease anatomy for optimal clinical management.

Rare Association Between Atrioventricular Septal Defect and Partial Anomalous Pulmonary Venous Connection

Clinical data

Infant, 7 months, female, referred to our department at one month of age, suspecting of congenital heart disease for further investigation.

Chest radiography

Demonstrates cardiomegaly and prominent pulmonary vascular markings.

Electrocardiography

Shows right ventricular hypertrophy and left anterior fascicular block.

Echocardiography

Evidenced common atrioventricular valve with two orifices and the left superior pulmonary vein draining on the brachiocephalic vein.

Computed tomography angiography

This complementary imaging exam was performed to confirm the diagnosis.

Diagnosis

The patient presented an association between AVSD and PAPVC, a rare combination. The clinical picture of heart failure was preponderant, characterized by need for diuretics and complementary exams findings, and early surgical treatment was indicated.

Operation

The operation was performed through a median sternotomy with 123 minutes of cardiopulmonary bypass and 89 minutes of cross-clamping time. The patient had no postoperative complications, remaining 10 days hospitalized.

Development and evolution of the metazoan heart

The mechanisms of the evolution and development of the heart in metazoans are highlighted, starting with the evolutionary origin of the contractile cell, supposedly the precursor of cardiomyocytes. The last eukaryotic common ancestor is likely a combination of several cellular organisms containing their specific metabolic pathways and genetic signaling networks. During evolution, these tool kits diversified. Shared parts of these conserved tool kits act in the development and functioning of pumping hearts and open or closed circulations in such diverse species as arthropods, mollusks, and chordates. The genetic tool kits became more complex by gene duplications, addition of epigenetic modifications, influence of environmental factors, incorporation of viral genomes, cardiac changes necessitated by air‐breathing, and many others. We evaluate mechanisms involved in mollusks in the formation of three separate hearts and in arthropods in the formation of a tubular heart. A tubular heart is also present in embryonic stages of chordates, providing the septated four‐chambered heart, in birds and mammals passing through stages with first and second heart fields. The four‐chambered heart permits the formation of high‐pressure systemic and low‐pressure pulmonary circulation in birds and mammals, allowing for high metabolic rates and maintenance of body temperature. Crocodiles also have a (nearly) separated circulation, but their resting temperature conforms with the environment. We argue that endothermic ancestors lost the capacity to elevate their body temperature during evolution, resulting in ectothermic modern crocodilians. Finally, a clinically relevant paragraph reviews the occurrence of congenital cardiac malformations in humans as derailments of signaling pathways during embryonic development.

The cardiac regulatory toolkit contains many factors including epigenetic, genetic, viral, hemodynamic, and environmental factors, but also transcriptional activators, repressors, duplicated genes, redundancies and dose‐dependancies.

Numerous toolkits regulate mechanisms including cell‐cell interactions, EMT, mitosis patterns, cell migration and differentiation and left/right sidedness involved in the development of endocardial cushions, looping, septum complexes, pharyngeal arch arteries, chamber and valve formation and conduction system.

Evolutionary development of the yolk sac circulation likely preceded the advent of endothermy in amniotes.

Parallel evolutionary traits regulate the development of contractile pumps in various taxa often in conjunction with the gut, lungs and excretory organs.

Altered ascending aortic wall shear stress in patients with corrected atrioventricular septal defect: a comprehensive cardiovascular magnetic resonance and 4D flow MRI evaluation

AIM

In patients after atrioventricular septal defect correction, altered geometry leads to a changed position and subsequent flow over the left ventricular outflow tract. We hypothesised that this altered flow may influence haemodynamics in the ascending aorta.

METHODS

In total, 30 patients after atrioventricular septal defect correction (age 27.6 ± 12.8 years) and 28 healthy volunteers (age 24.8 ± 13.7 years) underwent 4D flow cardiovascular magnetic resonance. Left ventricular ejection fraction and mean and peak wall shear stress calculated at ascending aortic peak systole were obtained from cardiovascular magnetic resonance. Left ventricular outflow tract data including velocity and diameter were obtained from echocardiography.

RESULTS

Patients showed a higher mean (911 ± 173 versus 703 ± 154 mPa, p = 0.001) and peak ascending aortic wall shear stress (1264 ± 302 versus 1009 ± 240 mPa, p = 0.001) compared to healthy volunteers. Increased blood flow velocities over the left ventricular outflow tract (1.49 ± 0.30 m/s versus 1.22 ± 0.20 m/s, p &lt; 0.001) correlated well with mean and peak ascending aortic wall shear stress (r = 0.67, p &lt; 0.001 and r = 0.77, p &lt; 0.001).

CONCLUSION

After atrioventricular septal defect correction, increased wall shear stress was observed, which correlated to velocities over the left ventricular outflow tract. These findings imply that altered outflow tract geometry contributes to changed aortic haemodynamics.

The Role of Non-Coding RNA in Congenital Heart Diseases

Cardiovascular development is a complex developmental process starting with the formation of an early straight heart tube, followed by a rightward looping and the configuration of atrial and ventricular chambers. The subsequent step allows the separation of these cardiac chambers leading to the formation of a four-chambered organ. Impairment in any of these developmental processes invariably leads to cardiac defects. Importantly, our understanding of the developmental defects causing cardiac congenital heart diseases has largely increased over the last decades. The advent of the molecular era allowed to bridge morphogenetic with genetic defects and therefore our current understanding of the transcriptional regulation of cardiac morphogenesis has enormously increased. Moreover, the impact of environmental agents to genetic cascades has been demonstrated as well as of novel genomic mechanisms modulating gene regulation such as post-transcriptional regulatory mechanisms. Among post-transcriptional regulatory mechanisms, non-coding RNAs, including therein microRNAs and lncRNAs, are emerging to play pivotal roles. In this review, we summarize current knowledge on the functional role of non-coding RNAs in distinct congenital heart diseases, with particular emphasis on microRNAs and long non-coding RNAs.

A familial congenital heart disease with a possible multigenic origin involving a mutation in BMPR1A

The genetics of many congenital heart diseases (CHDs) can only unsatisfactorily be explained by known chromosomal or Mendelian syndromes. Here, we present sequencing data of a family with a potentially multigenic origin of CHD. Twelve of nineteen family members carry a familial mutation [NM_004329.2:c.1328 G > A (p.R443H)] which encodes a predicted deleterious variant of BMPR1A. This mutation co-segregates with a linkage region on chromosome 1 that associates with the emergence of severe CHDs including Ebstein's anomaly, atrioventricular septal defect, and others. We show that the continuous overexpression of the zebrafish homologous mutation bmpr1aa^p.R438H within endocardium causes a reduced AV valve area, a downregulation of Wnt/ß-catenin signalling at the AV canal, and growth of additional tissue mass in adult zebrafish hearts. This finding opens the possibility of testing genetic interactions between BMPR1A and other candidate genes within linkage region 1 which may provide a first step towards unravelling more complex genetic patterns in cardiovascular disease aetiology.

Focal adhesions are essential to drive zebrafish heart valve morphogenesis

Gunawan et al. analyze at single-cell resolution collective endocardial cell migration into the extracellular matrix and the cellular rearrangements forming leaflets during zebrafish heart valve formation. They show that focal adhesion activity driven by Integrin α5β1 and Talin1 are essential to drive cardiac valve morphogenesis in zebrafish.

Elucidating the morphogenetic events that shape vertebrate heart valves, complex structures that prevent retrograde blood flow, is critical to understanding valvular development and aberrations. Here, we used the zebrafish atrioventricular (AV) valve to investigate these events in real time and at single-cell resolution. We report the initial events of collective migration of AV endocardial cells (ECs) into the extracellular matrix (ECM), and their subsequent rearrangements to form the leaflets. We functionally characterize integrin-based focal adhesions (FAs), critical mediators of cell–ECM interactions, during valve morphogenesis. Using transgenes to block FA signaling specifically in AV ECs as well as loss-of-function approaches, we show that FA signaling mediated by Integrin α5β1 and Talin1 promotes AV EC migration and overall shaping of the valve leaflets. Altogether, our investigation reveals the critical processes driving cardiac valve morphogenesis in vivo and establishes the zebrafish AV valve as a vertebrate model to study FA-regulated tissue morphogenesis.

Never too Grown-Up for a Congenital Heart Disease: Diagnosis of Transitional Atrioventricular Canal in a 50-Year-Old Male

Transitional atrioventricular (AV) septal defects are uncommon congenital heart defects, and diagnosis is usually made in childhood. We present the case of intermediate AV canal diagnosed in a man referring to cardiological examination for the first time in his life at the age of fifty for exertional dyspnea. The absence of medical examination or execution of electrocardiogram or echocardiogram in childhood or in youth and the very late appearance of symptoms lead to a late diagnosis of this congenital heart disease (CHD). This case underlines the importance of including CHD in the differential diagnosis of symptoms such as chronic dyspnea, also in adulthood.

Bradyarrhythmias in Repaired Atrioventricular Septal Defects: Single-Center Experience Based on 34 Years of Follow-Up of 522 Patients

Atrioventricular Septal Defect (AVSD) is a rare congenital heart defect (CHD) often associated with genetic syndromes, most commonly Down syndrome (DS). Over the last four decades, surgical repair has increased survival and improved quality of life in these patients. The prevalence of bradyarrhythmias namely, atrioventricular block (AVB) and sinus node dysfunction (SND) in AVSD is partially known. 522 cases with both partial and complete AVSD (38.7% with DS), undergoing intracardiac repair from 1982 to 2016 at our institution, were reviewed from our system database. 38 (7.3%) patients received permanent PM implantation for AVB (early or late) or SND. On one hand, AVB requiring PM was found in 26 (4.98%). This was further subdivided into early-onset 14 (2.6%) and late-onset AVB 12 (2.2%) (median 4 [IQR 1-7] years). On the other hand, 12 (2.3%) experienced late SND requiring PM (median 11 [IQR 3.5-15.2] years). Early and late AVB were independent from the type of AVSD (partial or complete), whereas the late SND was remarkably observed in complete AVSD compared to partial AVSD (p = 0.017). We classified the cohort into two main categories: DS (202, 38.7%) and non-DS (320, 61.3%). At Kaplan-Meier survival analysis, DS was significantly associated with late-onset bradyarrhythmias (p = 0.024). At Cox regression analysis, we identified DS as an independent predictor of PM implantation (HR 2.17). In conclusion, about 7% of repaired AVSD patients need PM implantation during follow-up. There are no differences in early and late AVB occurrence according to the type of AVSD. There is a higher incidence of late SND in repaired complete AVSD, with a later timing onset in patients with associated DS. Moreover, DS seems to be an independent predictor of PM implantation.

Small 4p16.3 deletions: Three additional patients and review of the literature

Wolf-Hirschhorn syndrome is a well-defined disorder due to 4p16.3 deletion, characterized by distinct facial features, intellectual disability, prenatal and postnatal growth retardation, and seizures. Genotype-phenotype correlations based on differently sized deletions have been attempted, and some candidate genes have been suggested. We report on clinical characteristics of three patients with pure interstitial submicroscopic 4p16.3 deletions, ranging in size from 68 to 166 kb, involving WHSCR1 and/or part of WHSCR2, and review published cases with overlapping 4p16.3 losses. The present study highlights a major role of NSD2 gene in the pathogenesis of the WHS main features and predicts that loss-of-function mutations affecting NSD2 gene could result in microcephaly, prenatal and postnatal growth retardation, psychomotor and language delay, and craniofacial features. Absent seizures in all subjects corroborate the suggestion that this specific feature is causally linked with at least one additional causative gene. Finally, we suggest that mir-943 could play a role in the pathogenesis of CHD in some of these patients.

Atrioventricular Canal and Dextrocardia: A Case Report with Implications for Community-Based Providers

Congenital heart defects (CHD) are the most common congenital malformation reported in the literature, with a global incidence of eight per every 1,000 live births. In the United States approximately 40,000 infants are born each year with a CHD. Of the infants diagnosed with a CHD, one in every four heart defects are life threatening in origin. Early identification and treatment of congenital heart lesions, beginning with a comprehensive physical assessment after birth, are critical. For infants delivered at community-based hospitals, the importance of the physical assessment, timing of diagnostic strategies, anticipatory planning, and interprofessional collaboration among referring and accepting centers cannot be understated. This article presents a rare case of an infant with atrioventricular canal complicated by dextrocardia. Embryology, pathophysiology, epidemiology, symptomology, cardiac assessment, diagnostics, treatment, and nursing strategies for facilitating transfer of care from community-based hospitals to tertiary medical centers are discussed.

Heterozygous missense mutations in NFATC1 are associated with atrioventricular septal defect

Atrioventricular septal defect (AVSD) may occur as part of a complex disorder (e.g., Down syndrome, heterotaxy), or as isolate cardiac defect. Multiple lines of evidence support a role of calcineurin/NFAT signaling in AVSD, and mutations in CRELD1, a protein functioning as a regulator of calcineurin/NFAT signaling have been reported in a small fraction of affected subjects. In this study, 22 patients with isolated AVSD and 38 with AVSD and heterotaxy were screened for NFATC1 gene mutations. Sequence analysis identified three missense variants in three individuals, including a subject with isolated AVSD [p.(Ala367Val)], an individual with AVSD and heterotaxy [p.(Val210Met)], and a subject with AVSD, heterotaxy, and oculo-auriculo-vertebral spectrum (OAVS) [p.(Ala696Thr)], respectively. The latter was also heterozygous for a missense change in TBX1 [p.(Pro86Leu)]. Targeted resequencing of genes associated with AVSD, heterotaxy, or OAVS excluded additional hits in the three mutation-positive subjects. Functional characterization of NFATC1 mutants documented defective nuclear translocation and decreased transcriptional transactivation activity. When expressed in zebrafish, the three NFATC1 mutants caused cardiac looping defects and altered atrioventricular canal patterning, providing evidence of their functional relevance in vivo. Our findings support a role of defective NFATC1 function in the etiology of isolated and heterotaxy-related AVSD.

Long-term outcomes following partial atrioventricular septal defect (AVSD) repair in Ireland

BACKGROUND

We describe the long-term results of partial atrioventricular septal defect (AVSD) repair in a single centre encompassing a 22-year period. Described are rates of survival, reoperation and complications.

METHODS

We performed a retrospective review of 556 patients undergoing AVSD repair to identify the 51 patients who underwent partial AVSD repair in Our Lady's Children's Hospital, Crumlin, Ireland, between 1993 and 2015 with long-term follow-up where available.

RESULTS

A total of 29 (56.8%) of patients were male and mean age at operation was 3.32 years. Mean weight was 13.2 kg. Trisomy 21 was present in 29 (56.8%). Five patients (9.6%) had undergone prior surgery. Mean cardiopulmonary bypass time was 89 ± 36 min and mean aortic cross-clamp time was 57 ± 28 min. One patient underwent partial AVSD repair and concomitant tracheal resection and extracorporeal membrane oxygenation decannulation. One patient was managed with suture atrial septal defect (ASD) closure, the remainder with patch repair of ASD and mitral cleft closure. The length of hospital stay was 9 ± 5 days. Median follow-up was 6.06 years (IQR, 1.65-10.2 years). There were no early mortalities. One patient died 1 year following surgery (1.9%). One patient required reoperation at an interval of 2 years for severe mitral regurgitation (1.9%).

CONCLUSIONS

Short- and long-term survival following partial AVSD repair in Ireland revealed excellent results compared with other published series. Reoperation incidence also compared excellently with other reports published in the literature.

Some Isolated Cardiac Malformations Can Be Related to Laterality Defects

Human beings are characterized by a left–right asymmetric arrangement of their internal organs, and the heart is the first organ to break symmetry in the developing embryo. Aberrations in normal left–right axis determination during embryogenesis lead to a wide spectrum of abnormal internal laterality phenotypes, including situs inversus and heterotaxy. In more than 90% of instances, the latter condition is accompanied by complex and severe cardiovascular malformations. Atrioventricular canal defect and transposition of the great arteries—which are particularly frequent in the setting of heterotaxy—are commonly found in situs solitus with or without genetic syndromes. Here, we review current data on morphogenesis of the heart in human beings and animal models, familial recurrence, and upstream genetic pathways of left–right determination in order to highlight how some isolated congenital heart diseases, very common in heterotaxy, even in the setting of situs solitus, may actually be considered in the pathogenetic field of laterality defects.

Pdgfrb is a direct regulatory target of TGFβ signaling in atrioventricular cushion mesenchymal cells

Cushion formation is the initial step for the development of valvuloseptal structures in mammalian hearts. TGFβ signaling plays critical roles in multiple steps of cushion morphogenesis. We used a newly developed conditional immortal atrioventricular cushion mesenchymal cell line, tsA58-AVM, to identify the TGFβ regulatory target genes through microarray analysis. Expression of ~1350 genes was significantly altered by TGFβ1 treatment. Subsequent bioinformatic analysis of TGFβ activated genes revealed that PDGF-BB signaling is the top hit as the potential upstream regulator. Among the 37 target molecules, 10 genes known to be involved in valve development and hemostasis were selected for quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis. Our results confirmed that they are all upregulated by TGFβ1 stimulation in tsA58-AVM cells and in primary atrioventricular cushion cells. We focused on examining regulation of Pdgfrb by TGFβ1, which encodes a tyrosine kinase receptor for PDGF-BB. We found that the ~150bp Pdgfrb promoter can respond to TGFβ stimulation and that this response relies on the two SP1 binding sites within the promoter. Co-immunoprecipitation analysis confirmed SP1 interacts with SMAD2 in a TGFβ-dependent fashion. Furthermore, SMAD2 is associated with the Pdgfrb promoter and this association is diminished by knocking down expression of Sp1. Our data therefore collectively suggest that upon TGFβ stimulation, SP1 recruits SMAD2 to the promoter of Pdgfrb to up-regulate its expression and thus Pdgfrb is a direct downstream target of the TGFβ/SMAD2 signaling.

The Dorsal Mesenchymal Protrusion and the Pathogenesis of Atrioventricular Septal Defects

Congenital heart malformations are the most common type of defects found at birth. About 1% of infants are born with one or more heart defect on a yearly basis. Congenital Heart Disease (CHD) causes more deaths in the first year of life than any other congenital abnormality, and each year, nearly twice as many children die in the United States from CHD as from all forms of childhood cancers combined. Atrioventricular septal defects (AVSD) are congenital heart malformations affecting approximately 1 in 2000 live births. Babies born with an AVSD often require surgical intervention shortly after birth. However, even after successful surgery, these individuals typically have to deal with lifelong complications with the most common being a leaky mitral valve. In recent years the understanding of the molecular etiology and morphological mechanisms associated with the pathogenesis of AVSDs has significantly changed. Specifically, these studies have linked abnormal development of the Dorsal Mesenchymal Protrusion (DMP), a Second Heart Field-derived structure, to the development of this congenital defect. In this review we will be discuss some of the latest insights into the role of the DMP in the normal formation of the atrioventricular septal complex and in the pathogenesis of AVSDs.

Complete Unbalanced Atrioventricular Septal Defect With a Common Arterial Trunk in an Uncontrolled Type 1 Diabetic Mother

When performed by a trained sonographer, fetal echocardiography can be instrumental in identifying cardiac pathology and abnormal cardiac physiology before a baby is born. Even though the diagnostic accuracy of a fetal echocardiogram can be limited by maternal body habitus, gestational age, and fetal position, sequential exams allow for detailed analysis of the cardiac structures. Early identification and diagnosis of intrauterine cardiac anomalies and subsequent pregnancy management and delivery planning are essential to providing the best possible outcome for fetuses born with heart defects. In this case study, we describe a rare combination of congenital heart defects diagnosed in an uncontrolled type 1 diabetic mother while in her second trimester of pregnancy.