A healthy heart beats anywhere from 60 to 100 times every minute. An arrhythmia is a deviation from that normal rhythm. Bradycardia refers to an arrhythmia in which the heart beats too slowly; tachycardia to a heart beating too quickly. Fibrillation is when the heartbeat is sporadic or skips a beat here and there. Sometimes, the changes in rhythm are very apparent to the person experiencing them, while it's just as possible that the person won't notice a thing until long-term symptoms, such as fatigue, dizziness, shortness of breath and fainting, begin to show up. There's a wide array of possible causes for arrhythmia, from heart defects and high blood pressure to stress and certain medications. There's also a wide array of treatment options -- in some cases, doctors may choose to keep an eye on the situation, while in others, they may recommend medications, surgery or insertion of a pacemaker.