I went to the hospital, the results stated that the heart was diagnosed with atrial septal defect. I also often have difficulty breathing, my heart beats fast when I exercise, sometimes I feel very uncomfortable with my heart throbbing, I also often have headaches and feel like I don't have any strength. A year ago, I fainted but for unknown reasons, I just remember losing my ability to stand, I don't know if it has anything to do with the heart. Doctor tell me what is atrial septal defect? Shortness of breath with heart palpitations is heart disease? Doctor, please help me with the answer, thank you for the advice.