Molecular Pathways and Animal Models of Tetralogy of Fallot and Double Outlet Right Ventricle.

Tetralogy of Fallot and double-outlet right ventricle are outflow tract (OFT) alignment defects situated on a continuous disease spectrum. A myriad of upstream causes can impact on ventriculoarterial alignment that can be summarized as defects in either i) OFT elongation during looping morphogenesis or ii) OFT remodeling during cardiac septation. Embryological processes underlying these two developmental steps include deployment of second heart field cardiac progenitor cells, establishment and transmission of embryonic left/right information driving OFT rotation and OFT cushion and valve morphogenesis. The formation and remodeling of pulmonary trunk infundibular myocardium is a critical component of both steps. Defects in myocardial, endocardial, or neural crest cell lineages can result in alignment defects, reflecting the complex intercellular signaling events that coordinate arterial pole development. Importantly, however, OFT alignment is mechanistically distinct from neural crest-driven OFT septation, although neural crest cells impact indirectly on alignment through their role in modulating signaling during SHF development. As yet poorly understood nongenetic causes of alignment defects that impact the above processes include hemodynamic changes, maternal exposure to environmental teratogens, and stochastic events. The heterogeneity of causes converging on alignment defects characterizes the OFT as a hotspot of congenital heart defects.

[Management of postoperative arrhythmias in the tetralogy of Fallot: a literature review]. / Gestione delle aritmie cardiache dopo correzione chirurgica della tetralogia di Fallot: revisione della letteratura.

Tetralogy of Fallot (ToF) occurs in about 4 births/1000/year and represents about one tenth of all congenital heart diseases. Nowadays 86% of patients reach adulthood with corrective surgery. Before the 1980s, these patients were treated only with "surgical palliation", which consisted in the creation of a systemic to pulmonary artery shunt or a pulmonary valvulotomy, whereas after the introduction of extracorporeal circulation, corrective surgery is performed electively between 3 and 6 months of life. After repair patients during their life may develop hemodynamic lesions, including right ventricular outflow tract dysfunction, and arrhythmias which can occur in over 30% of cases. It is estimated that these patients present a risk of sudden death of 0.2%/year. Therefore, for the prevention and treatment of arrhythmic events, a periodic follow-up in specialized centres for adult congenital heart disease is mandatory, because most often arrhythmias are triggered by the presence of hemodynamic lesions, first of all pulmonary regurgitation.

Identification of a de novo LRP1 mutation in a Saudi family with Tetralogy of Fallot.

BACKGROUND: Tetralogy of Fallot (TOF) is a rare, complex congenital heart defect caused by genetic and environmental interactions that results in abnormal heart development during the early stages of pregnancy. Genetic basis of TOF in Saudi populations is not yet studied. Therefore, the objective of this study is to screen for the molecular defects causing TOF in Saudi patients. METHODS: A family with non-syndromic TOF was recruited from the Western region of Saudi Arabia. Whole exome sequencing (WES) was performed on the proband and her parents. The identified candidate variant was verified by sanger sequencing. Also, different computational biology tools were used to figure out how candidate variants affect the structure and function of candidate protein involved in TOF. RESULTS: A novel heterozygous de novo mutation in LRP1 (p. G3311D) gene was identified in the index case. Also, this variant was absent in the in-house exome sequencing data of 80 healthy Saudi individuals. This variant was predicted to be likely pathogenic, as it negatively affects the biophysical chemical properties and stability of the protein. Furthermore, functional biology data from knock out mouse models confirms that molecular defects in LRP1 gene leads to cardiac defects and lethality. This variant was not previously reported in both Arab and global population genetic databases. CONCLUSION: The findings in this study postulate that the LRP1 variant has a role in TOF pathogenesis and facilitate accurate diagnosis as well as the understanding of underlying molecular mechanisms and pathophysiology of the disease.

The Case of a 44-Year-Old Survivor of Unrepaired Tetralogy of Fallot, Right Aortic Arch and Abdominal Aortopulmonary Collateral Vessels.

The most common congenital cyanotic heart disease is described in the literature as the Tetralogy of Fallot. This abnormality is characterized by the presence of ventricular septal defect (VSD), obstruction of the right ventricular (RV) outflow tract, right ventricular hypertrophy, and overriding aorta. In patients with pulmonary atresia with ventricular septal defect (PA/VSD), major aortopulmonary collateral arteries (MAPCA) are common; however, although some of them do not have PA/VSD, they do have other particular anatomical variants. The case we are presenting in this article is a rare mild symptomatic adult noncorrected TOF, with preserved RV function, right aortic arch, and MAPCAs ("classic" thoracic MAPCAs but also abdominal MAPCAs). The anatomy of a complex congenital defect is well illustrated by cardiac magnetic resonance (CMR) and computer tomography angiography (CTA), and these imaging techniques are mostly used to understand the relative clinical "silence" TOF. Imaging scans thus play a key role in the evaluation of these patients, being very important to know the indications and limitations of each method, but also to learn to combine them with each other depending on the clinical picture of the patient's presentation. Additionally, the close collaboration between clinicians and imagers is essential for a correct, complete and detailed preoperative evaluation, being subsequently essential for cardiovascular surgeons, the whole team thus deciding the best therapeutic management.

Integrated multi-omic characterization of congenital heart disease.

The heart, the first organ to develop in the embryo, undergoes complex morphogenesis that when defective results in congenital heart disease (CHD). With current therapies, more than 90% of patients with CHD survive into adulthood, but many suffer premature death from heart failure and non-cardiac causes1. Here, to gain insight into this disease progression, we performed single-nucleus RNA sequencing on 157,273 nuclei from control hearts and hearts from patients with CHD, including those with hypoplastic left heart syndrome (HLHS) and tetralogy of Fallot, two common forms of cyanotic CHD lesions, as well as dilated and hypertrophic cardiomyopathies. We observed CHD-specific cell states in cardiomyocytes, which showed evidence of insulin resistance and increased expression of genes associated with FOXO signalling and CRIM1. Cardiac fibroblasts in HLHS were enriched in a low-Hippo and high-YAP cell state characteristic of activated cardiac fibroblasts. Imaging mass cytometry uncovered a spatially resolved perivascular microenvironment consistent with an immunodeficient state in CHD. Peripheral immune cell profiling suggested deficient monocytic immunity in CHD, in agreement with the predilection in CHD to infection and cancer2. Our comprehensive phenotyping of CHD provides a roadmap towards future personalized treatments for CHD.

Brainstem and cerebellar volumes at magnetic resonance imaging are smaller in fetuses with congenital heart disease.

BACKGROUND: Congenital heart disease is associated with an increased risk of smaller brain volumes and structural brain damage, and impaired growth of supratentorial brain structures in utero has been linked to poor neurodevelopmental outcomes. However, little is known on brainstem and cerebellar volumes in fetuses with congenital heart disease. Moreover, it is not clear whether impaired infratentorial growth, if present, is associated with only certain types of fetal cardiac defects or with supratentorial brain growth, and whether altered biometry is already present before the third trimester. OBJECTIVE: This study aimed to investigate brainstem and cerebellar volumes in fetuses with congenital heart disease and to compare them to infratentorial brain volumes in fetuses with normal hearts. Secondarily, the study aimed to identify associations between infratentorial brain biometry and the type of cardiac defects, supratentorial brain volumes, and gestational age. STUDY DESIGN: In this retrospective case-control study, 141 magnetic resonance imaging studies of 135 fetuses with congenital heart disease and 141 magnetic resonance imaging studies of 125 controls with normal hearts at 20 to 37 gestational weeks (median, 25 weeks) were evaluated. All cases and controls had normal birthweight and no evidence of structural brain disease or genetic syndrome. Six types of congenital heart disease were included: tetralogy of Fallot (n=32); double-outlet right ventricle (n=22); transposition of the great arteries (n=27); aortic obstruction (n=24); hypoplastic left heart syndrome (n=22); and hypoplastic right heart syndrome (n=14). First, brainstem and cerebellar volumes of each fetus were segmented and compared between cases and controls. In addition, transverse cerebellar diameters, vermian areas, and supratentorial brain and cerebrospinal fluid volumes were quantified and differences assessed between cases and controls. Volumetric differences were further analyzed according to types of cardiac defects and supratentorial brain volumes. Finally, volume ratios were created for each brain structure ([volume in fetus with congenital heart disease/respective volume in control fetus] × 100) and correlated to gestational age. RESULTS: Brainstem (cases, 2.1 cm3 vs controls, 2.4 cm3; P<.001) and cerebellar (cases, 3.2 cm3 vs controls, 3.4 cm3; P<.001) volumes were smaller in fetuses with congenital heart disease than in controls, whereas transverse cerebellar diameters (P=.681) and vermian areas (P=.947) did not differ between groups. Brainstem and cerebellar volumes differed between types of cardiac defects. Overall, the volume ratio of cases to controls was 80.8% for the brainstem, 90.5% for the cerebellum, and 90.1% for the supratentorial brain. Fetuses with tetralogy of Fallot and transposition of the great arteries were most severely affected by total brain volume reduction. Gestational age had no effect on volume ratios. CONCLUSION: The volume of the infratentorial brain, which contains structures considered crucial to brain function, is significantly smaller in fetuses with congenital heart disease than in controls from midgestation onward. These findings suggest that impaired growth of both supra- and infratentorial brain structures in fetuses with congenital heart disease occurs in the second trimester. Further research is needed to elucidate associations between fetal brain volumes and neurodevelopmental outcomes in congenital heart disease.

Accelerated Growth, Differentiation, and Ploidy with Reduced Proliferation of Right Ventricular Cardiomyocytes in Children with Congenital Heart Defect Tetralogy of Fallot.

The myocardium of children with tetralogy of Fallot (TF) undergoes hemodynamic overload and hypoxemia immediately after birth. Comparative analysis of changes in the ploidy and morphology of the right ventricular cardiomyocytes in children with TF in the first years of life demonstrated their significant increase compared with the control group. In children with TF, there was a predominantly diffuse distribution of Connexin43-containing gap junctions over the cardiomyocytes sarcolemma, which redistributed into the intercalated discs as cardiomyocytes differentiation increased. The number of Ki67-positive cardiomyocytes varied greatly and amounted to 7.0-1025.5/106 cardiomyocytes and also were decreased with increased myocytes differentiation. Ultrastructural signs of immaturity and proliferative activity of cardiomyocytes in children with TF were demonstrated. The proportion of interstitial tissue did not differ significantly from the control group. The myocardium of children with TF under six months of age was most sensitive to hypoxemia, it was manifested by a delay in the intercalated discs and myofibril assembly and the appearance of ultrastructural signs of dystrophic changes in the cardiomyocytes. Thus, the acceleration of ontogenetic growth and differentiation of the cardiomyocytes, but not the reactivation of their proliferation, was an adaptation of the immature myocardium of children with TF to hemodynamic overload and hypoxemia.

PARACENTRAL ACUTE MIDDLE MACULOPATHY ASSOCIATED WITH BRANCH RETINAL ARTERY OCCLUSION DUE TO POLYCYTHEMIA IN A PATIENT WITH TETRALOGY OF FALLOT.

PURPOSE: To describe the occurrence of paracentral acute middle maculopathy (PAMM) associated with branch retinal artery occlusion secondary to polycythemia in a patient with tetralogy of Fallot. METHODS: Case report. RESULTS: A 30-year-old man presented with acute vision loss and superior visual deficit in his left eye for two days. His medical record had a tetralogy of Fallot. Complete blood count showed an erythrocyte count of 9.88 million/µL (4.4-5.6), hemoglobin of 17.7 g/dL (13.5-16.9), and hematocrit of 65.4% (40-49). The best-corrected visual acuity was 20/25 in the left eye, and a diagnosis of left inferotemporal branch retinal artery occlusion was made. Spectral-domain optical coherence tomography revealed a characteristic hyperreflective band-like lesion on the inner nuclear layer consistent with PAMM. CONLUSION: Polycythemia may be a trigger for branch retinal artery occlusion-associated PAMM. We suggest a new precursor cause of PAMM that is previously undescribed.

Second instance of co-occurring 22q11.2 deletion syndrome and Williams syndrome.

We present an 18-month-old male with Tetralogy of Fallot, retrognathia, short stature, global developmental delay, and dysmorphic features who was found to have dual diagnoses of both Williams syndrome and 22q11.2 deletion syndrome (22q11.2DS). To our knowledge, this is the second case of such a co-occurrence documented in the medical literature. Our patient presents with a blended physical phenotype of these two conditions and a behavioral phenotype that is distinct from what is typically observed in either disorder alone. We compare our patient's phenotype to the previously reported case and to the typical phenotypes for each individual condition. Additionally, we discuss why the occurrence of these two disorders together seems to be so rare, and the benefit of a genetics evaluation to an inpatient service team and the patient.

Circulation derived from 4D flow MRI correlates with right ventricular dysfunction in patients with tetralogy of Fallot.

We used 4D-flow MRI to investigate circulation, an area integral of vorticity, in the main pulmonary artery (MPA) as a new hemodynamic parameter for assessing patients with a repaired Tetralogy of Fallot (TOF). We evaluated the relationship between circulation, right ventricular (RV) function and the pulmonary regurgitant fraction (PRF). Twenty patients with a repaired TOF underwent cardiac MRI. Flow-sensitive 3D-gradient sequences were used to obtain 4D-flow images. Vortex formation in the MPA was visualized, with short-axis and longitudinal vorticities calculated by software specialized for 4D flow. The RV indexed end-diastolic/end-systolic volumes (RVEDVi/RVESVi) and RV ejection fraction (RVEF) were measured by cine MRI. The PR fraction (PRF) and MPA area were measured by 2D phase-contrast MRI. Spearman ρ values were determined to assess the relationships between circulation, RV function, and PRF. Vortex formation in the MPA occurred in 15 of 20 patients (75%). The longitudinal circulation (11.7 ± 5.1 m2/s) was correlated with the RVEF (ρ = - 0.85, p = 0.0002), RVEDVi (ρ = 0.62, p = 0.03), and RVESVi (ρ = 0.76, p = 0.003) after adjusting for the MPA size. The short-axis circulation (9.4 ± 3.4 m2/s) in the proximal MPA was positively correlated with the MPA area (ρ = 0.61, p = 0.004). The relationships between the PRF and circulation or RV function were not significant. Increased longitudinal circulation in the MPA, as demonstrated by circulation analysis using 4D flow MRI, was related to RV dysfunction in patients with a repaired TOF.

Use of stable isotope-tagged thymidine and multi-isotope imaging mass spectrometry (MIMS) for quantification of human cardiomyocyte division.

Quantification of cellular proliferation in humans is important for understanding biology and responses to injury and disease. However, existing methods require administration of tracers that cannot be ethically administered in humans. We present a protocol for the direct quantification of cellular proliferation in human hearts. The protocol involves administration of non-radioactive, non-toxic stable isotope 15Nitrogen-enriched thymidine (15N-thymidine), which is incorporated into DNA during S-phase, in infants with tetralogy of Fallot, a common form of congenital heart disease. Infants with tetralogy of Fallot undergo surgical repair, which requires the removal of pieces of myocardium that would otherwise be discarded. This protocol allows for the quantification of cardiomyocyte proliferation in this discarded tissue. We quantitatively analyzed the incorporation of 15N-thymidine with multi-isotope imaging spectrometry (MIMS) at a sub-nuclear resolution, which we combined with correlative confocal microscopy to quantify formation of binucleated cardiomyocytes and cardiomyocytes with polyploid nuclei. The entire protocol spans 3-8 months, which is dependent on the timing of surgical repair, and 3-4.5 researcher days. This protocol could be adapted to study cellular proliferation in a variety of human tissues.

A rare mutant of OFD1 gene responsible for Joubert syndrome with significant phenotype variation.

Joubert syndrome (JBTS), a rare genetic disorder resulted from primary cilium defects or basal-body dysfunction, is characterized by agenesis of cerebellar vermis and abnormal brain stem. Both genotypes and phenotypes of JBTS are highly heterogeneous. The identification of pathogenic gene variation is essential for making a definite diagnosis on JBTS. Here, we found that hypoplasia of cerebellar vermis occurred in three male members in a Chinese family. Then, we performed whole exome sequencing to identify a novel missense mutation c.599T > C (p. L200P) in the OFD1 gene which is the candidate gene of X-linked JBTS (JBST10). The following analysis showed that the variant was absent in the 1000 Genomes, ExAC and the 200 female controls; the position 200 Leucine residue was highly conserved across species; the missense variant was predicted to be deleterious using PolyPhen-2, PROVEAN, SIFT and Mutation Taster. The OFD1 expression was heavily lower in the proband and an induced male fetus compared with a healthy male with a wild-type OFD1 gene. The in vitro expression analysis of transiently transfecting c.599T or c.599C plasmids into HEK-293T cells confirmed that the missense mutation caused OFD1 reduction at the protein level. And further the mutated OFD1 decreased the level of Gli1 protein, a read-out of Sonic hedgehog (SHH) signaling essential for development of central neural system. A known pathogenic variant c.515T > C (p. L172P) showed the similar results. All of these observations suggested that the missense mutation causes the loss function of OFD1, resulting in SHH signaling impairs and brain development abnormality. In addition, the three patients have Dandy-Walker malformation, macrogyria and tetralogy of Fallot, respectively, the latter two of which are firstly found in JBTS10 patients. In conclusion, our findings expand the context of genotype and phenotype in the JBTS10 patients.

A loss-of-function mutation p.T256M in NDRG4 is implicated in the pathogenesis of pulmonary atresia with ventricular septal defect (PA/VSD) and tetralogy of Fallot (TOF).

Pulmonary atresia with ventricular septal defect (PA/VSD) is a rare congenital heart disease (CHD) characterized by a lack of luminal continuity and blood flow from either the right ventricle or the pulmonary artery, together with VSDs. The prevalence of PA/VSD is about 0.2% of live births and approximately 2% of CHDs. PA/VSD is similar to tetralogy of Fallot (TOF) in terms of structural and pathological characteristics. The pathogenesis of these two CHDs remains incompletely understood. It was previously reported that N-myc downstream-regulated gene (NDRG)4 is required for myocyte proliferation during early cardiac development. In the present study, we enrolled 80 unrelated patients with PA/VSD or TOF and identified a probably damaging variant p.T256M of NDRG4. The p.T256M variant impaired the proliferation ability of human cardiac myocytes (hCM). Furthermore, the p.T256M variant resulted in G1 and G2 arrest of hCM, followed by an increase in p27 and caspase-9 expression. Our results provide evidence that the p.T256M variant in NDRG4 is a pathogenic variant associated with impaired hCM proliferation and cell-cycle arrest and likely contributes towards the pathogenesis of PA/VSD and TOF.

Isolated subclavian or brachiocephalic arteries with tetralogy of Fallot, left retro-aortic brachiocephalic vein.

BACKGROUND: Isolated subclavian or brachiocephalic artery are uncommon aortic arch anomalies. Here we report the anatomy and histology of this disease. METHODS: Four cases of congenital isolated subclavian or brachiocephalic artery in fetuses are described. RESULTS: We identified one case of right aortic arch with isolated left subclavian artery associated with the tetralogy of Fallot, two cases of right aortic arch with isolated left brachiocephalic artery (one case with left retro-aortic brachiocephalic vein), and one case of left aortic arch with isolated right subclavian artery associated with coarctation of the aorta and cervical aortic arch. The proximal subclavian or brachiocephalic artery is arterial duct. CONCLUSION: Aortic arches with an isolated subclavian or brachiocephalic artery are often associated with the tetralogy of Fallot. It also can be associated with rare abnormalities such as left retro-aortic brachiocephalic vein or cervical aortic arch. Isolated LBA can be associated with microdeletion chromosome 22q11.

The 30-Year Outcomes of Tetralogy of Fallot According to Native Anatomy and Genetic Conditions.

BACKGROUND: The reported survival of tetralogy of Fallot (TOF) is > 97%. Patients with pulmonary atresia and/or genetic conditions have worse outcomes, but long-term estimates of survival and morbidity for these TOF subgroups are scarce. The objective of this study was to describe the 30-year outcomes of TOF according to native anatomy and the coexistence of genetic conditions. METHODS: The TRIVIA (Tetralogy of Fallot Research for Improvement of Valve Replacement Intervention: A Bridge Across the Knowledge Gap) study is a retrospective population-based cohort including all TOF subjects born from 1980 to 2015 in Québec. We evaluated all-cause mortality by means of Cox proportional hazards regression, and cumulative mean number of cardiovascular interventions and unplanned hospitalisations with the use of marginal means/rates models. We computed 30-year estimates of outcomes according to TOF types, ie, classic TOF (cTOF) and TOF with pulmonary atresia (TOF-PA), and the presence of genetic conditions. RESULTS: We included 960 subjects. The median follow-up was 17 years (interquartile range, 8-27). Nonsyndromic cTOF subjects had a 30-year survival of 95% and had undergone a mean of 2.8 interventions and 0.5 hospitalisations per subject. In comparison, TOF-PA subjects had a lower 30-year survival of 78% and underwent a mean of 8.1 interventions, with 4 times as many hospitalisations. The presence of a genetic condition was associated with lower survival (< 85% for cTOF and < 60% for TOF-PA) but similar numbers of interventions and hospitalisations. CONCLUSIONS: The anatomic types and the presence of genetic conditions strongly influence the long-term outcomes of TOF. We provided robust 30-year estimates for key markers of prognosis that may be used to improve risk stratification and provide more informed counselling to families.

Angiographic Anatomy of Major Aortopulmonary Collateral Arteries and Association With Early Surgical Outcomes in Tetralogy of Fallot.

Background Due in part to the heterogeneity of the pulmonary circulation in patients with tetralogy of Fallot and major aortopulmonary collateral arteries (MAPCAs), research on this condition has focused on relatively basic anatomic characteristics. We aimed to detail pulmonary artery (PA) and MAPCA anatomy in a large group of infants, assess relationships between anatomy and early surgical outcomes, and consider systems for classifying MAPCAs. Methods and Results All infants ( <1 year of age) undergoing first cardiac surgery for tetralogy of Fallot/MAPCAs from 2001 to 2019 at Stanford University were identified. Preoperative angiograms delineating supply to all 18 pulmonary segments were reviewed for details of each MAPCA and the arborization and size of central PAs. We studied 276 patients with 1068 MAPCAs and the following PA patterns: 152 (55%) incompletely arborizing PAs, 48 (17%) normally arborizing PAs, 45 (16%) absent PAs, and 31 (11%) unilateral MAPCAs. There was extensive anatomic variability, but no difference in early outcomes according to PA arborization or the predominance of PAs or MAPCAs. Patients with low total MAPCA and/or PA cross-sectional area were less likely to undergo complete repair. Conclusions MAPCA anatomy is highly variable and essentially unique for each patient. Though each pulmonary segment can be supplied by a MAPCA, central PA, or both, all anatomic combinations are similarly conducive to a good repair. Total cross-sectional area of central PA and MAPCA material is an important driver of outcome. We elucidate a number of novel associations between anatomic features, but the extreme variability of the pulmonary circulation makes a granular tetralogy of Fallot/MAPCA classification system unrealistic.

Ex vivo cardiovascular magnetic resonance diffusion weighted imaging in congenital heart disease, an insight into the microstructures of tetralogy of Fallot, biventricular and univentricular systemic right ventricle.

PURPOSE: Common types of congenital heart disease exhibit a variety of structural and functional variations which may be accompanied by changes in the myocardial microstructure. We aimed to compare myocardial architecture from magnetic resonance diffusion tensor imaging (DTI) in preserved pathology specimens. MATERIALS AND METHODS: Pathology specimens (n = 24) formalin-fixed for 40.8 ± 7.9 years comprised tetralogy of Fallot (TOF, n = 10), dextro-transposition of great arteries (D-TGA, n = 8) five with ventricular septal defect (VSD), systemic right ventricle (n = 4), situs inversus totalis (SIT, n = 1) and levo-TGA (L-TGA, n = 1). Specimens were imaged using a custom spin-echo sequence and segmented automatically according to tissue volume fraction. In each specimen T1, T2, fractional anisotropy, mean diffusivity, helix angle (HA) and sheet angle (E2A) were quantified. Pathologies were compared according to their HA gradient, HA asymmetry and E2A mean value in each myocardial segment (anterior, posterior, septal and lateral walls). RESULTS: TOF and D-TGA with VSD had decreased helix angle gradient by - 0.34°/% and remained symmetric in the septum in comparison to D-TGA without VSD. Helix angle range was decreased by 45°. It was associated with a decreased HA gradient in the right ventricular (RV) wall, i.e. predominant circumferential myocytes. The sheet angle in the septum of TOF was opposing those of the left ventricular (LV) free wall. Univentricular systemic RV had the lowest HA gradient (- 0.43°/%) and the highest HA asymmetry (75%). HA in SIT was linear, asymmetric, and reversed with a sign change at about 70% of the depth at mid-ventricle. In L-TGA with VSD, HA was asymmetric (90%) and its gradients were decreased in the septum, anterior and lateral wall. CONCLUSION: The organization of the myocytes as determined by DTI differs between TOF, D-TGA, L-TGA, systemic RV and SIT specimens. These differences in cardiac structure may further enlighten our understanding of cardiac function in these diverse congenital heart diseases.

BVES downregulation in non-syndromic tetralogy of fallot is associated with ventricular outflow tract stenosis.

BVES is a transmembrane protein, our previous work demonstrated that single nucleotide mutations of BVES in tetralogy of fallot (TOF) patients cause a downregulation of BVES transcription. However, the relationship between BVES and the pathogenesis of TOF has not been determined. Here we reported our research results about the relationship between BVES and the right ventricular outflow tract (RVOT) stenosis. BVES expression was significantly downregulated in most TOF samples compared with controls. The expression of the second heart field (SHF) regulatory network genes, including NKX2.5, GATA4 and HAND2, was also decreased in the TOF samples. In zebrafish, bves knockdown resulted in looping defects and ventricular outflow tract (VOT) stenosis, which was mostly rescued by injecting bves mRNA. bves knockdown in zebrafish also decreased the expression of SHF genes, such as nkx2.5, gata4 and hand2, consistent with the TOF samples` results. The dual-fluorescence reporter system analysis showed that BVES positively regulated the transcriptional activity of GATA4, NKX2.5 and HAND2 promoters. In zebrafish, nkx2.5 mRNA partially rescued VOT stenosis caused by bves knockdown. These results indicate that BVES downregulation may be associated with RVOT stenosis of non-syndromic TOF, and bves is probably involved in the development of VOT in zebrafish.

Separate arch origin of the left external carotid artery with common trunk giving rise to the left internal carotid artery and left subclavian artery.

We present a case of a 3-year-old boy with tetralogy of Fallot having the direct origin of the left external carotid artery from the aorta with a common trunk giving rise to the left internal carotid artery and left subclavian artery, in a right-sided aortic arch. We also highlight the potential implications in management.