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Ebstein's anomaly of the tricuspid valve (TV) is a congenital cardiac malformation of the tricuspid valve (TV) and right ventricle (RV) characterized by downward displacement of the functional annulus usually involving septal and inferior leaflets. Ebstein's anatomical spectrum is highly variable. This anatomical study aimed to unravel the morphogenetic mechanisms underlying this variability. Forty-two hearts exhibiting Ebstein anomaly from the Reference Center for Complex Congenital Heart Defects (CHD) collection were macroscopically analysed: 28 isolated and 14 associated with another CHD. Tricuspid leaflets, right ventricle (RV), and associated lesions were analysed. Measurements were related to fetal heart reference values according to gestational age. Specimens were classified depending on the distal insertion of the anterior leaflet: linear, hyphenated or focal. Among isolated Ebstein hearts, distal insertion of the anterior leaflet was linear in 36%, hyphenated in 29% and focal in 36%. Linear insertion was always associated with anterior TV orifice and absent inferior leaflet, with absent septal leaflet in 80%. Atrialisation (thin, paper-like, inferior RV wall) was found in 90% of the linear forms and 37.5% of the hyphenated forms, which were associated with various degrees of inferior and septal leaflets non-delaminationanomalies. In focal forms, only the septal leaflet was involved, and there was no atrialisation. Ventricular septal defect was found in 3 specimens, Uhl-like RV anterior wall in 2, including 1 with left ventricle non compaction. Associated Ebstein anomalies were predominantly found in pulmonary atresia with intact ventricular septum; there was no atrialisation and septal leaflet only was involved. Ebstein anomaly corresponds to an arrest in TV development, early in linear forms, late in focal forms, intermediate in hyphenated forms. Atrialisation was always associated with absent inferior leaflet, underlining developmental interaction between endocardial cushions and myocardium at the RV inferior wall. [ABSTRACT FROM AUTHOR]

Pulmonary atresia with intact ventricular septum (PA-IVS) means pulmonary valvar atresia without a ventricular septal defect (VSD). In PA-IVS, the right ventricle (RV) appears externally normal in size but the internal cavity is hypoplastic with major wall hypertrophy. Histology reveals myocardial disarray and endocardial fibroelastosis. The leaflets of the pulmonary valve are present but fused indicating an acquired lesion during fetal life. The files of all children with PA-IVS in our institution between 1981 and 2023 were reviewed, using a data warehouse to look for associated VSD. Patients with Ebstein anomaly and pulmonary atresia were excluded. When available, echocardiographic examinations were reviewed. One patient had severe coronary arterial anomaly leading to death and autopsy. The total cohort included 300 consecutive patients. Among those, we found 8 children with an associated VSD (2.6% of the cohort). According to the IPCCC-ICD11 nomenclature, the VSD was central perimembranous in 3, muscular in 4, outlet in 1. In this last patient, autopsy revealed a hypoplastic but not malaligned outlet septum, without aortic overriding, which discarded the diagnosis of tetralogy of Fallot (Fig. 1). Paradoxically, the presence of a VSD is compatible with diagnosis of PA-IVS. This rare association cannot be classified as "PA-VSD": this last term should be reserved to extreme forms of tetralogy of Fallot, associating outlet VSD, anteriorly malaligned outlet septum, overriding aorta and PA. Conversely, PA-IVS may be due to a RV myocardial disease, leading to a diminutive RV cavity, tricuspid valve hypoplasia and progressive fusion of the pulmonary leaflets leading to atresia. The anatomic type of VSD, muscular and perimembranous, and their rarity, are in favor of an incidental association. The imprecise term "PA-IVS" does not reflect the defect's anatomy and pathogenesis. It should then be modified, as it is crucial to use an accurate terminology to better describe congenital heart defects. [ABSTRACT FROM AUTHOR]