Atrial Septum Defect. There is a comunication between the right and left atrium ( upper chambers of the heart) that remains open by the time of birth, and if it is big enough, low oxigenized blood from the right atrium will be mixed to the oxigenized blood in the left atrium, and this can cause improper cell oxigenation.
Surgery is done by stitching or fixing a patch over the " hole". Heart will function normally and you´ll be good as new.
As for the As cycle...You know you are at a higher risk to develop endocarditis, so a series of IM injections would be potentially dangerous without antibiotic profilaxis, and taking antibiotics for weeks is just not wise.
If I were you I´d do Oxandrolone and creatine.