[Echographic rediscovery of an anatomical structure: the Chiari network. Apropos of 16 cases].

In 1897, the anatomist Chiari described a structure in the right atrium connected to the Eustachian valve identified as the embryological vestige of the right valve of the sinus venosus. This structure was then forgotten. Recently, Werner described the echocardiographic appearances. During 1981, 1 600 consecutive patients underwent 2D echocardiography and the right atrium (RA) was visualised in several incidences. Abnormal RA echos fulfilling the echocardiographic criteria of the Chiari network were detected in 16 cases. The 2D echo appearances were as follows: a fine, mobile echo crossing the RA at right angles to its long antero posterior axis; arising from the anterior border of the orifice of the inferior vena cava, variably attached to the RA walls (lateral, superior, interatrial septum). The recordings were made from the transverse parasternal and apical or subcostal 4 chamber views. An M mode recording of this structure usually guided by the sector scan was made in 13 patients. This showed a fine curvilinear echo animated by antero-posterior vibrations during the cardiac cycle situated behind the anterior tricuspid leaflet. The pathological associations of the 16 patients in whom the Chiari network was demonstrated were as follows: 5 congenital cardiopathies including 3 ASDs, 1 isolated abnormal pulmonary venous drainage, 1 complex case comprising 1 ASD and 5 acquired lesions: aortic endocarditis; chronic cor pulmonale, idiopathic atrial fibrillation, pericarditis and coronary artery disease. Six patients did not appear to have cardiac disease. This structure was confirmed at surgery in 2 cases: the operative findings were a fine network of filaments stretching from the orifice of the inferior vena cava (Eustachian valve) to the RA walls.(ABSTRACT TRUNCATED AT 250 WORDS)