Atrial septal defects (ASD) are common congenital malformations of the wall of tissue that separates the right and left upper cavities of the heart. There are three different types of atrial septal defects, depending on the location of the malformation: (1) inlet atrial septal defect, which occurs at the entrance of the vein that carries blood from the head, arms, and upper body, (2) a secundum atrial septal defect, which occurs in the body of the wall of tissues separating the right and left upper cavities, and (3) a primum or outlet atrial septal defect which occurs in the portion of the heart that separates the upper cavities from the lower cavities of the heart.
A precise incidence rate for atrial septal defects is hard to determine, but it is estimated that atrial septal defects account for 7.5% of all congenital heart defects.
It can be difficult to accurately diagnosis an atrial septal defect via prenatal ultrasound, and the accuracy rate is low. As an isolated diagnosis, atrial septal defects are not fatal; however, these defects are often associated with fatal diagnoses.
The majority of cases of ASDs are random, so the recurrence risk is non-existent. There have been cases in which ASDs have been present in the parents and/or multiple children.