title: Cor triatriatum or divided atriums: which approach provides the better understanding?
abstract: It is frequent, in the current era, to encounter congenital cardiac malformations described in terms of "cor triatriatum". But can hearts be truly found with three atrial chambers? The morphological method, emphasised by Van Praagh et al, states that structures within the heart should be defined on the basis of their most constant components. In the atrial chambers, it is the appendages that are the most constant components, and to the best of our knowledge, hearts can only possess two appendages, which can be of either right or left morphology. The hearts described on the basis of "cor triatriatum", nonetheless, can also be analysed on the basis of division of either the morphologically right or the morphologically left atriums. In this review, we provide a description of cardiac embryology, showing how each of the atrial chambers possesses part of the embryological body, along with an appendage, a vestibule, a venous component, and a septum that separates them. We then show how it is, indeed, the case that the hearts described in terms of "cor triatriatum" can be readily understood on the basis of division of these atrial components. In the right atrium, it is the venous valves that divide the chamber. In the left atrium, it is harder to provide an explanation for the shelf that produces atrial division. We also contrast the classic examples of the divided atrial chambers with the vestibular shelf that produces supravalvar stenosis in the morphologically left atrium, showing that this form of obstruction needs to be distinguished from the fibrous shelves producing intravalvar obstruction.
authors.affiliation: 1Department of Paediatric Cardiology,University Hospital Southampton NHS Foundation Trust,United Kingdom.
authors.forename: Tara
authors.initials: T
authors.lastname: Bharucha
authors.affiliation: 2Department of Pediatric Cardiology,University of Florida,Gainesville,Florida,United States of America.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Spicer
authors.affiliation: 4Division of Developmental Biology,MRC National Institute for Medical Research,London,United Kingdom.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mohun
authors.affiliation: 1Department of Paediatric Cardiology,University Hospital Southampton NHS Foundation Trust,United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Black
authors.affiliation: 6Emeritus Founding Editor,Chapel Hill,North Carolina, United States of America.
authors.forename: G William
authors.initials: GW
authors.lastname: Henry
authors.affiliation: 1Department of Paediatric Cardiology,University Hospital Southampton NHS Foundation Trust,United Kingdom.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Anderson
mesh_terms: D020517:Atrial Appendage / Q000002:abnormalities / Q000196:embryology*; D003310:Cor Triatriatum / Q000196:embryology* / Q000473:pathology; D006321:Heart / Q000196:embryology*; D006325:Heart Atria / Q000002:abnormalities / Q000196:embryology; D006801:Humans; D008946:Mitral Valve Stenosis / Q000196:embryology / Q000473:pathology
keywords: persistent left superior caval vein