An irregular heartbeat may produce no symptoms, or you may perceive it as a skipped beat, palpitation or fluttering sensation in the chest or neck, states the American Heart Association. If the irregular heartbeat, or arrhythmia, continues and affects the heart's function, chest pain, fatigue, dizziness, shortness of breath and fainting may occur. Doctors use physical examinations, analyses of medical and family histories, and tests such as electrocardiograms to diagnose arrhythmias, explains the National Heart, Lung, and Blood Institute.
The electrocardiogram is the most common test for detecting heart arrhythmias, states the National Heart, Lung, and Blood Institute. It shows how fast the heart beats and its rhythm, but if the arrhythmia does not occur during the test, the electrocardiogram cannot record the episode. The doctor may have you wear a Holter monitor, which records your heart's electrical activity for 24 to 48 hours, or an event monitor, which records the heart's electrical activity at certain times -- usually when you activate it while you are experiencing symptoms. Alternatively, he may implant a loop recorder under the skin in the chest to help determine the reason for arrhythmias and fainting spells. The loop recorder provides information for 12 to 24 months.
The doctor may also order an echocardiogram, which can identify damaged heart muscle, parts of the heart that don't contract correctly and areas of the heart that receive poor blood flow, notes the National Heart, Lung, and Blood Institute. He may test your blood for potassium and thyroid hormone levels, as abnormal levels can indicate arrhythmias. He may perform an electrophysiology study, a test that triggers an arrhythmia and allows the doctor to find out if a particular medication alleviates the arrhythmia.