After at least 20 years, however, approximately 15 percent of patients develop progressively more severe pulmonary vascular disease. These patients are often found with a history of frequent upper respiratory tract infections and slight shortness of breath. Those of the ostium primum involve the inferior portion of the atrial septum and border on the tricuspid valve. In most instances, the exact cause of an atrial septal defect is not known. Possible causes include intrauterine rubella syndrome, fetal alcohol syndrome , and lithium use during pregnancy.
Chromosomal abnormalities can also play a role.
Most women that have had an ASD repaired tolerate pregnancy well, but a 6 percent risk exists of having a child with the same defect. The outlook of ASD Many patients found with a secundum ASD do not require intervention. Most of the ASDs in these patients close spontaneously, and those that do not close, spontaneously decrease in size. Spontaneous closure occurs because the growth of the heart stretches the edges of the ellipsoid defect, thus bringing the edges together. After this age, secundum ASDs rarely close.