Fainting (syncope) can affect anybody at one time or another. Normally it is the result of harmless circulatory problems. However, if the fainting episodes occur more often, doctors need to discover why they are occurring and then treat the problem. In the field of cardiology, fainting is caused mainly by a heart rate that is either too slow or too fast. Diagnostically conclusive testing includes ECG, exercise stress test, long-term ECG and the use of an event recorder, either externally or as an implanted device. In the event of the heart rate being too slow, a cardiac pacemaker is usually implanted. If the heart rate is too fast or the heartbeat races, an electrophysiological examination and catheter ablation or an AICD implantation are carried out.