What's it mean to have atrial septal defect?

Depends...: Depends on the size and the amount of blood it is allowing to leak from the left to the right heart chambers which in turn causes strain on the right heart. This can cause shortness of breath and arrhythmias. Patient with medium size defects may not have any problems until their middle age and patients with smaller defects can lead a full healthy life without even knowing it.

4 types: Congenital absence of part or all of the interatrial septum. Secundum, primum type, sinus venosus type, foramen ovale type and unroofed coronary sinus(does not involve the septum but behaves the same). These lesions result in left to right shunting and right ventricular and pulmonary volume overload. May be missed at birth, symptoms worse after 2 weeks old if large. Diagnosed on echocardiogram.

Atrial septal defect: An atrial septel defect is a hole or opening in the tissue that separates the left and right atrium. They are classified by location and named primum, secundum or patent foramen ovale. They can be observed or in some cases treated surgically to close them.