While some heart rhythm disorders may go unnoticed, others may cause symptoms ranging from a mild fluttering in the chest, to a feeling of breathlessness, to even blacking out. Several different heart rhythm disorders, including fast arrhythmias (tachycardia), abnormally slow rhythms (bradycardia), and extra beats, may cause similar symptoms in different people. Therefore, heart rhythm specialists can use a variety of different heart tests to look at the heart’s structure and circulation, as well as the heart’s electrical system, in order to pinpoint the exact cause of arrhythmia symptoms and decide on a treatment plan.