An esophago-atrial vein or fibrous cord in a top fold of the oblique sinus of the pericardial sac.

In a previous anatomical study of the oblique sinus of pericardium, we reported on the morphological variations of this recess. We noted a previously undescribed variation of its top in 32.7% of our cases. Here we detail this variation using microscopic and macroscopic mediastinal dissections of 107 adult fresh cadavers. It seems a top fold of the oblique sinus contains a permeable esophago-atrial vein or a fibrous cord. These unique variations of the oblique sinus modify the classical anatomical and embryological descriptions. Abnormal esophago-atrial veins have not been described previously but they are predictable according to embryological knowledge. From a clinical point of view, such a vein, permeable or not, may facilitate extension of esophageal carcinoma to the pericardium and may represent a porto-systemic bypass in cases of portal hypertension.