A 77-year old woman was referred to our centre for evaluation of a mitral regurgitation. The patient was in New York Heart Association Class II and otherwise feeling well.
Transoesophageal echocardiography revealed a severe mitral regurgitation due to a large prolapse of the posterior leaflet with a ruptured chorda causing a flail leaflet in the lateral segment P2. As a coincidental finding, the interatrial septum was observed to contain multiple small cavities—leading to a ‘chambered’ appearance. No shunt on the atrial level was detected. Flow patterns in the chambers were suggestive for a communication with the left atrium. The chambered part of the septum was inferior and posterior of (and not involving) the fossa ovalis.
This is the first description of a chambered interatrial septum. As a differential diagnosis multiple left atrial pouches or a double-layered interatrial septum could be considered. However, both entities refer to a residual overlap due to incomplete fusion of the septum primum and the septum secundum, which is covering the fossa ovalis. Since this process starts caudal and proceeds in cranial direction, pouches are localized superior and anterior of the fossa ovalis. Regarding the fact that the cavities in the present case are very much inferior and not involving this area, we are confident that this is the description of a novel entity of intraseptal cavities. Description of novel septal anomalies is particularly important in light of the increasing numbers of procedures using transseptal punctures. Such knowledge is crucial to perform safe and effective procedures.
(Panel A, Supplemetary data online, Movie 1) View of the interatrial septum from the right atrium. The chambered part of the septum (white oval line) lies inferior and posterior of the fossa ovalis (*) and clearly distant from the area where pouches would be expected (**). AV, aortic valve; CS, coronary sinus; IVC, inferior vena cava, SVC, superior vena cava. (Panel B, Supplemetary data online, Movie 2) Bicaval view (left) and modified four-chamber view (right) depicting multiple cavities in the interatrial septum. Large Eustachian valve. (Panels C and D, Supplemetary data online, Movie 3 and 4) Reconstruction of different mid-oesophageal planes (90°, 0°, 45°, and 135°), demonstrating the localization and extent of the chambered part of the septum. Area where pouches would be expected (**). (Supplemetary data online, Movie 5) Color loop of the interatrial septum 80°,"PFO view". (Supplemetary data online, Movie 6) Color loop of the interatrial septum 115°.
Supplementary data are available at European Heart Journal - Cardiovascular Imaging online.
