Atrial Septal Defects

Types of Atrial Septal Defects

• The American College of Cardiology notes that secundum atrial septal defects are the most common type of ASD, resulting from deficiency in the septum primum, excessive resorption of the septum primum, or deficiency in the septum secundum, and are located in the region of the fossa ovalis 1, 2
• The American Heart Association indicates that primum atrial septal defects are a variant of atrioventricular septal defect, characterized by interatrial communication just above the atrioventricular valve, no interventricular communication below the atrioventricular valve, separate right and left atrioventricular valvular orifices, and varying degrees of malformation of the left-sided component of the common atrioventricular valve 1, 2
• The European Society of Cardiology states that sinus venosus defects are characterized by a vena cava and/or pulmonary vein(s) that overrides the atrial septum or septum secundum, producing an interatrial or anomalous venoatrial communication, and are often associated with partial anomalous pulmonary venous connection 1, 2, 3
• The American College of Cardiology notes that unroofed coronary sinus defects are a direct communication between the left atrium and the coronary sinus, resulting from defective development of the wall between the coronary sinus and the left atrium 1, 2
• The American College of Cardiology indicates that patent foramen ovale is a small interatrial communication confined to the region of the fossa ovalis, characterized by no deficiency of septum primum and a normal limbus with no deficiency of the septum secundum 1, 4

Associated Anatomical Variations

• The American College of Cardiology notes that atrial septal aneurysm is an abnormally large and redundant septum primum that results in aneurysmal protrusion into one or both atria 1, 2
• The American College of Cardiology indicates that cor triatriatum sinister is a partition that divides the left atrium into a posterior chamber receiving pulmonary veins and an anterior chamber communicating with the left atrial appendage 1
• The American College of Cardiology states that hyperlipomatous interatrial septum is increased interatrial septal thickness caused by lipid deposition 1, 2