Sudden death in idiopathic (congenital) right atrial enlargement. Postmortem findings and review of cases

A case of idiopathic enlargement of the right atrium is presented and 13 other cases are reviewed. The patient whose case is reported died suddenly at home 6 months after onset of atrial flutter. This represents the first case in which postmortem findings are available. The patient demonstrates that the anomaly cannot be considered entirely benign as has been suggested in previous reports. Other complications that may occur particularly in cases of massive atrial enlargement are atrial arrhythmias, syncope, and right ventricular compression. The importance of recognizing this condition as a clinical entity is stressed because surgical excision of a portion of the enlarged atrium appears to be both easy and curative and because these cases may be mistakenly diagnosed as mediastinal tumor or pericardial effusion. The possible relationship of this apparently congenital abnormality to Uhl's anomaly is discussed.