THE NATURE OF THE SUPERIOR SINUS VENOSUS DEFECT

The location, and morphology, of the superior sinus venosus interatria l communication remains contentious. As part of a clinical study, we e xamined anatomic specimens and echocardiograms so as to clarify the ar rangement of the normal atrial septal structures, and compared them wi th the arrangement found in the superior sinus venosus defect. The pat hognomonic diagnostic criterion in the abnormal hearts was overriding of the intact muscular rim of the oval fossa by the mouth of the super ior caval vein. This muscular rim is, in reality, a tube of myocardium which encloses a core of extracardiac adipose tissue. Understanding o f this anatomic conundrum clarifies the understanding of the structure s of both the normal atrial septum and sinus venosus defects. Clin. An at. 11:349-352, 1998. (C) 1998 Wiley-Liss, Inc.