Long-term results after the réparation à l'étage ventriculaire procedure for transposition of the great arteries and double-outlet right ventricle with pulmonary stenosis.

OBJECTIVES: The purpose of this study is to describe the long-term results of the 'réparation à l'étage ventriculaire' (REV) technique for double-outlet right ventricle and transposition of the great arteries (TGA) with pulmonary stenosis (PS). METHODS: Between 1980 and 2021, 157 patients underwent a REV procedure (median age and weight: 20.8 months and 7.7 kg). The most frequent anatomical presentation was the association between TGA, ventricular septal defect and PS (n = 116, 73.9%). RESULTS: Sixty-seven patients (42.7%) underwent a Rashkind procedure, and 67 patients (42.7%) a prior surgical palliation (including 62 systemic-to-pulmonary artery shunts). Resection of the conal septum and/or ventricular septal defect enlargement was performed in 109 patients (69.4%). Thirteen patients (8.3%) died, including 4 during the first postoperative month and 2 after heart transplant. Overall survival at 40 years was 89.3%. Thirty-seven patients (23.6%) required 68 reinterventions on the right ventricular outflow tract (RVOT), including 49 reoperations, with a median delay of 9 years after the REV (8 months to 27 years). Twenty patients (12.7%) underwent RVOT valvulation (16 surgical and 4 interventional). Freedom from RVOT reintervention and reoperation at 40 years were 60.3% and 62.6%, respectively. Four patients (2.5%) required reoperation for left ventricular outflow tract obstruction, with a median delay of 4.8 years. CONCLUSIONS: The REV procedure is a good alternative for TGA and double-outlet right ventricle with PS patients. Only a quarter of the patients required redo surgery on the RVOT. Reoperations for left ventricular outflow tract obstruction are scarce.

Identification of Greb1l as a genetic determinant of crisscross heart in mice showing torsion of the heart tube by shortage of progenitor cells.

Despite their burden, most congenital defects remain poorly understood, due to lack of knowledge of embryological mechanisms. Here, we identify Greb1l mutants as a mouse model of crisscross heart. Based on 3D quantifications of shape changes, we demonstrate that torsion of the atrioventricular canal occurs together with supero-inferior ventricles at E10.5, after heart looping. Mutants phenocopy partial deficiency in retinoic acid signaling, which reflect overlapping pathways in cardiac precursors. Spatiotemporal gene mapping and cross-correlated transcriptomic analyses further reveal the role of Greb1l in maintaining a pool of dorsal pericardial wall precursor cells during heart tube elongation, likely by controlling ribosome biogenesis and cell differentiation. Consequently, we observe growth arrest and malposition of the outflow tract, which are predictive of abnormal tube remodeling in mutants. Our work on a rare cardiac malformation opens novel perspectives on the origin of a broader spectrum of congenital defects associated with GREB1L in humans.

Transient Nodal Signaling in Left Precursors Coordinates Opposed Asymmetries Shaping the Heart Loop.

The secreted factor Nodal, known as a major left determinant, is associated with severe heart defects. Yet, it has been unclear how it regulates asymmetric morphogenesis such as heart looping, which align cardiac chambers to establish the double blood circulation. Here, we report that Nodal is transiently active in precursors of the mouse heart tube poles, before looping. In conditional mutants, we show that Nodal is not required to initiate asymmetric morphogenesis. We provide evidence of a heart-specific random generator of asymmetry that is independent of Nodal. Using 3D quantifications and simulations, we demonstrate that Nodal functions as a bias of this mechanism: it is required to amplify and coordinate opposed left-right asymmetries at the heart tube poles, thus generating a robust helical shape. We identify downstream effectors of Nodal signaling, regulating asymmetries in cell proliferation, differentiation, and extracellular matrix composition. Our study uncovers how Nodal regulates asymmetric organogenesis.

Mesoderm patterning by a dynamic gradient of retinoic acid signalling.

Retinoic acid (RA), derived from vitamin A, is a major teratogen, clinically recognized in 1983. Identification of its natural presence in the embryo and dissection of its molecular mechanism of action became possible in the animal model with the advent of molecular biology, starting with the cloning of its nuclear receptor. In normal development, the dose of RA is tightly controlled to regulate organ formation. Its production depends on enzymes, which have a dynamic expression profile during embryonic development. As a small molecule, it diffuses rapidly and acts as a morphogen. Here, we review advances in deciphering how endogenously produced RA provides positional information to cells. We compare three mesodermal tissues, the limb, the somites and the heart, and discuss how RA signalling regulates antero-posterior and left-right patterning. A common principle is the establishment of its spatio-temporal dynamics by positive and negative feedback mechanisms and by antagonistic signalling by FGF. However, the response is cell-specific, pointing to the existence of cofactors and effectors, which are as yet incompletely characterized. This article is part of a discussion meeting issue 'Contemporary morphogenesis'.

Antenatal nephromegaly and propionic acidemia: a case report.

BACKGROUND: Propionic acidemia (PA) is a rare but severe recessive autosomal disease, presenting with non specific signs in the first years of life. Prenatal diagnosis is invasive (amniocentesis) and limited to suspect cases. No screening test has been described, in particular no correlations between prenatal sonography and PA have been documented so far. CASE PRESENTATION: We report the case of a boy with fetal bilateral nephromegaly and hyperechogenic kidneys, along with neonatal acute kidney injury; no etiology could be found in the first months of life. At 3 months of life, he presented with tachypnea and altered mental status, which lead to the diagnosis of PA. The renal ultrasound at 8 months of life, after a symptomatic treatment of PA had been initiated, showed a regression of the renal abnormalities. CONCLUSION: This case describes PA as a novel cause of large and hyperechogenic kidneys in the antenatal period. It suggests that, when confronted to fetal nephromegaly, hyperechogenic kidneys and risk factors of metabolic disease such as consanguineous parents, PA should be considered, and a prenatal test should be proposed.