atrial septal defect coronary sinus atrial septal defect 2010-09-27T10:22:34Z interatrial communication (atrial septal defect) through coronary sinus orifice, that is characterized by the absence of at least a portion of the common wall that separates the coronary sinus and the left atrium; interatrial shunting occurs through the defect in the wall on the left atrial side, which is continuous with the orifice of the coronary sinus opening on the right atrial side of the septum csmith MPheno.ontology MP:0010407 coronary sinus ASD