[Aneurysm of the interauricular septum and operated left-right shunt. Echocardiographic aspects].

The echocardiographic appearances of a patient with a rare congenital malformation, interatrial septal aneurysm (IASA) associated with a hemodynamically significant left-to-right shunt, are described. A 52 year old man with Noonan's syndrome was admitted to hospital for atrial flutter with right heart failure, which, on investigation, led to the diagnosis of a rare type of atrial septal defect; 2D echocardiography showed an isolated aneurysm of the interatrial septum; cardiac catheterisation demonstrated a significant left-to-right (5 volumes of oxygen per 100 ml). The patient underwent surgery which confirmed the presence of a multiperforated aneurysm of the interatrial septum in the region of the fossa ovalis. This abnormality was resected and the interatrial defect closed; there were no postoperative complications and the cardiomegaly regressed significantly. The authors underline the M mode and 2D appearances of this condition; although it may be difficult on M mode examination to distinguish an IASA from other conditions giving rise to mobile intra-right atrial echos, such as Chiari's malformation, tricuspid valve vegetations, intraatrial tumour or thrombus or Eustachian valve, 2D examination using different incidences and contrast injections generally confirms the diagnosis. Surgery is often necessary after the detection of this echocardiographic abnormality: the surgical indications are described.