An ASD is a hole in the wall that separates the two upper chambers of the heart. There are many different kinds of ASDs, and they can be diagnosed in both children and adults. Some ASDs only require follow-up observation, but many require surgical repair. In some cases, ASDs can be repaired non-surgically using specialized closure devices placed within the heart during a minimally invasive catheterization procedure. Evaluation and treatment of ASDs should be performed by doctors who specialize in congenital heart disease as complications may occur when they are treated incorrectly.