Arrangement of the systemic and pulmonary venous components of the atrial chambers in hearts with isomeric atrial appendages

Background: The morphological definition of atrial chambers, and the determ ination of atrial laterality, are based on analysis of the structure of the atrial appendages. The systemic and pulmonary venous connections to the he art, nonetheless, are important in the management of patients having isomer ic appendages. In this study, therefore, we analysed the morphology of the postero-superior walls of the atrial chambers so as to provide evidence con cerning the morphogenetic background of those hearts, and to improve operat ive management. Methods: We reviewed 15 autopsied specimens with isomeric r ight appendages, and 10 with isomeric left appendages, paying particular at tention to the morphology of the systemic and pulmonary venous connections. The postero-superior walls of the atrial chambers can be made up of the at rial body, the systemic venous components, or the pulmonary venous componen t. We analysed the contributions made by each of these components. Results: The postero-superior walls of the atrial chambers were markedly variable, but could be grouped into five patterns. Bilaterally well-developed systemi c venous components and absence of the pulmonary venous component within th e hypoplastic atrial body were present in 9 hearts with extracardiac pulmon ary venous connections in the setting of right isomerism. Bilaterally well- developed systemic venous components, and a hypoplastic pulmonary venous co mponent within the hypoplastic atrial body, were present in 5 hearts with i ntracardiac pulmonary venous connections in right isomerism. Bilaterally we ll-developed systemic venous components, and a hypolastic pulmonary venous component within the sizable atrial body, were present in 1 heart with an i ntracardiac pulmonary venous connection in right isomerism. A well-develope d pulmonary venous component within the atrial body, and hypoplasia of one systemic venous component, were present in 7 hearts with left isomerism. A well-developed pulmonary venous component within the atrial body and hypopl asia of bilateral systemic venous components, were present in 3 hearts with left isomerism. Conclusions: The postero-superior walls of the atrial cham bers in hearts with isomeric atrial appendages can be analysed on the basis of a compound structure made of bilateral systemic venous components, a ce ntral pulmonary venous component, and the body of the atrium. Hearts with i someric right appendages have absence or hypoplasia of the pulmonary venous component, while hearts with isomeric left appendages have hypoplastic sys temic venous components.