This case series examines cardiac MRI findings in four children and adolescents admitted to intensive care in April 2020 for multisystem inflammatory syndrome and Kawasaki disease-like features related to COVID-19. Acute myocarditis occurred less than 1 week after onset of fever and gastrointestinal symptoms. Physical examination showed rash and cheilitis/conjunctivitis. All patients recovered after intravenous immunoglobulin therapy. SARS-CoV-2 RT-PCR was negative on nasopharyngeal, stool, and respiratory samples and was positive on serology. Cardiac MRI showed diffuse myocardial edema on T2-STIR sequences and native-T1 mapping, with no evidence of late gadolinium enhancement suggestive of replacement fibrosis or focal necrosis. These findings favor post-infectious myocarditis in children and adolescents with COVID-19.

Clinical analysis allowed us to refine the clinical description of CHARGE syndrome in fetuses, describe some novel features and set up diagnostic criteria in order to help the diagnosis of CHARGE syndrome after termination of pregnancies following the detection of severe malformations.

The frequency of malformations observed in patients with WT underline the need of genetic counseling and molecular genetic explorations for a better follow-up of these patients, with a frequently good outcome. A decisional tree, based on clinical observations of patients with WT, is proposed to guide clinicians for further molecular genetic explorations.

Aim This study determined the influence of the COVID‐19 pandemic on the occurrence of multisystem inflammatory syndrome in children (MIS‐C) and compared the main characteristics of MIS‐C and Kawasaki disease (KD). Methods We included patients aged up to 18 years of age who were diagnosed with MIS‐C or KD in a paediatric university hospital in Paris from 1 January 2018 to 15 July 2020. Clinical, laboratory and imaging characteristics were compared, and new French COVID‐19 cases were correlated with MIS‐C cases in our hospital. Results There were seven children with MIS‐C, from 6 months to 12 years of age, who were all positive for the virus that causes COVID‐19, and 40 virus‐negative children with KD. Their respective characteristics were as follows: under 5 years of age (14.3% vs. 85.0%), paediatric intensive care unit admission (100% vs. 10.0%), abdominal pain (71.4% vs. 12.5%), myocardial dysfunction (85.7% vs. 5.0%), shock syndrome (85.7% vs. 2.5%) and mean and standard deviation C‐reactive protein (339 ± 131 vs. 153 ± 87). There was a strong lagged correlation between the rise and fall in MIS‐C patients and COVID‐19 cases. Conclusion The rise and fall of COVID‐19 first wave mirrored the MIS‐C cases. There were important differences between MIS‐C and KD.

Background: Coronary artery (CA) stems connect the ventricular coronary tree with the aorta. Defects in proximal CA patterning are a cause of sudden cardiac death. In mice lacking Tbx1, common arterial trunk is associated with an abnormal trajectory of the proximal left CA. Here we investigate CA stem development in wild-type and Tbx1 null embryos. Results: Genetic lineage tracing reveals that limited outgrowth of aortic endothelium contributes to proximal CA stems. Immunohistochemistry and fluorescent tracer injections identify a periarterial vascular plexus present at the onset of CA stem development. Transplantation experiments in avian embryos indicate that the periarterial plexus originates in mesenchyme distal to the outflow tract. Tbx1 is required for the patterning but not timing of CA stem development and a Tbx1 reporter allele is expressed in myocardium adjacent to the left but not right CA stem. This expression domain is maintained in Sema3c 2/2 hearts with a common arterial trunk and leftward positioned CA. Ectopic myocardial differentiation is observed on the left side of the Tbx1

Conotruncal congenital heart defects, including defects in septation and alignment of the ventricular outlets, account for approximately a third of all congenital heart defects. Failure of the left ventricle to obtain an independent outlet results in incomplete separation of systemic and pulmonary circulation at birth. The embryonic outflow tract, a transient cylinder of myocardium connecting the embryonic ventricles to the aortic sac, plays a critical role in this process during normal development. The outflow tract (OFT) is derived from a population of cardiac progenitor cells called the second heart field that contributes to the arterial pole of the heart tube during cardiac looping. During septation, the OFT is remodeled to form the base of the ascending aorta and pulmonary trunk. Tbx1, the major candidate gene for DiGeorge syndrome, is a critical transcriptional regulator of second heart field development. DiGeorge syndrome patients are haploinsufficient for Tbx1 and present a spectrum of conotruncal anomalies including tetralogy of Fallot, pulmonary atresia, and common arterial trunk. In this review, we focus on the role of Tbx1 in the regulation of second heart field deployment and, in particular, in the development of a specific population of myocardial cells at the base of the pulmonary trunk. Recent data characterizing additional properties and regulators of development of this region of the heart, including the retinoic acid, hedgehog, and semaphorin signaling pathways, are discussed. These findings identify future subpulmonary myocardium as the clinically relevant component of the second heart field and provide new mechanistic insight into a spectrum of common conotruncal congenital heart defects.

Outflow tract defects, including cardiac neural crest defects (so-called conotruncal defects) and transposition of the great arteries, are due to an abnormal rotation of the outflow tract during cardiac development. Coronary orifices are often abnormal in outflow tract defects, particularly in common arterial trunk (CAT). A recent study indicates that abnormal coronary artery pattern in a mouse model with common arterial outlet (Tbx1À/À mouse mutant) could be due to a reduced and malpositioned subpulmonary coronary-refractory myocardial domain. The aim of our study was to demonstrate the relation between coronary orifices pattern in outflow tract defects in human and the abnormal embryonic rotation of the outflow tract. We analyzed 101 heart specimens with outflow tract defects: 46 CAT, 15 tetralogy of Fallot (TOF), 29 TOF with pulmonary atresia (TOF-PA), 11 double-outlet right ventricle with subaortic ventricular septal defect (DORV) and 17 controls. The position of left and right coronary orifices (LCO, RCO) was measured in degrees on the aortic/truncal circumference. The anterior angle between LCO and RCO (a) was calculated. The LCO was more posterior in TOF (31°), TOF-PA (47°), DORV (44°), CAT (63°), compared with controls (0°, P < 0.05), and more posterior in CAT than in other outflow tract defects (P < 0.05). The RCO was more anterior in TOF (242°), TOF-PA (245°) and DORV (271°) than in controls (213°, P < 0.05), but not in CAT (195°). The a angle was similar in TOF, TOF-PA, DORV and controls (149°, 162°, 133°, 147°), but significantly larger in CAT (229°, P < 0.0001). In all outflow tract defects but CAT, the displacement of LCO (anterior) and RCO (posterior), while the a angle remains constant, might be due to incomplete rotation of the myocardium at the base of the outflow tract, leading to an abnormally positioned subpulmonary coronary-refractory myocardial domain. The larger a angle in CAT could reflect its dual identity, aortic and pulmonary.

Half of the neonates with foetal CHD benefited from an urgent intervention or PGE1 infusion at birth. We recommend scheduled delivery and in utero transfer for transposition of the great arteries, double-outlet right ventricle with sub-pulmonary ventricular septal defect, total anomalous pulmonary venous connection, CHD with atrio-ventricular block with heart rate <50, all ductal-dependant lesions, and CHD with potentially ductal-dependant systemic flow.