The atrioventricular junctions in Ebstein malformation

• Published in: British heart journal 2000-04, Vol.83 (4), p.444-449
• Main Authors: Ho, S Y, Goltz, D, McCarthy, K, Cook, A C, Connell, M G, Smith, A, Anderson, R H
• Format: Article
• Language: English
• Subjects: atrioventricular node; Atrioventricular Node - abnormalities; Atrioventricular Node - embryology; Atrioventricular Node - pathology; Basic Research; Biological and medical sciences; bundle branch block; Bundle-Branch Block - etiology; Bundle-Branch Block - pathology; Cardiac arrhythmia; Cardiology. Vascular system; Congenital heart diseases. Malformations of the aorta, pulmonary vessels and vena cava; Coronary vessels; Ebstein Anomaly - complications; Ebstein Anomaly - pathology; Ebstein's anomaly; Electrocardiography; Fetuses; Heart; Heart attacks; Heart Ventricles - pathology; Humans; Infant, Newborn; Medical sciences; Morphology; Studies; Tricuspid Valve - pathology; Wolff-Parkinson-White syndrome
• ISSN: 1355-6037; 0007-0769; 1468-201X
• DOI: 10.1136/heart.83.4.444

OBJECTIVE To review the anatomical structure of the right atrioventricular junction, including the specialised atrioventricular conduction system, in hearts with Ebstein's malformation, to identify potential substrates for the abnormalities in conduction. METHODS Five heart specimens representing the morphological spectrum of Ebstein malformation were examined grossly and histologically. RESULTS On the endocardial surface, the atrioventricular junction was marked by a faint line in two hearts, and by a small ridge in the other three. Analysis of the right parietal junction in four hearts revealed only two accessory muscular atrioventricular connections. A plane of fibrofatty tissue separated atrial from ventricular myocardium in the right parietal junction in all hearts. The compact atrioventricular node was closer to the coronary sinus than usual. Accessory nodoventricular connections were present in four hearts, while accessory fasciculo-ventricular connections were found in one. The right bundle branch was hypoplastic or absent in four hearts. CONCLUSIONS In this small series, the parietal atrioventricular junction was better developed than previously thought. Structural abnormalities of the atrioventricular conduction system, however, were present. These may account for some of the conduction abnormalities frequently observed with the Ebstein malformation.