It likely depends on the size of the hole in the atrial septum and what symptoms you are having. The subject of flying with a atrial septum defect has its risks and is definitely a question for your cardiologist to answer.

According to the NIH, patients are generally advised not to fly.

Mayo Connect does not allow me to post a link yet after a week so Google this if you would like more detail. “Congenital heart disease and air travel”