Sometimes, especially if you do not have any noticeable symptoms of an arrhythmia, your doctor may find out you have one during a routine screening or physical for a competitive sport.
To diagnose an arrhythmia, your doctor will ask you about any symptoms, lifestyle habits, and other risk factors of arrhythmias. Your doctor will also do a physical exam, which may include these steps:
- Checking for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
- Checking your pulse to find out how fast your heart is beating
- Listening to the rate and rhythm of your heartbeat
- Listening to your heart for a heart murmur
- Looking for signs of other diseases, such as thyroid disease, that could be causing arrhythmias
If you or your child has a high risk of arrhythmias, your doctor may screen you regularly with heart tests. These tests, described in the next section, can help your doctor check whether your heartbeat is too fast, too slow, or irregular, even if you do not have any symptoms. Some of these tests may look at the heart’s structure and function or may determine if you have risk factors for developing an arrhythmia.
An electrocardiogram (EKG or ECG) is the most common test for diagnosing arrhythmias. An EKG records your heart’s electrical activity. Your doctor may do an EKG during a stress test, which records your heart’s activity when it is working hard and beating fast.
Your doctor may also do other tests to diagnose arrhythmias.
- Blood tests measure the level of certain substances in the blood, such as potassium or other electrolytes and thyroid hormone.
- Monitors for long-term recording include Holter monitors and implantable loop recorders. These record your heart rhythm while you do your normal activities. Holter monitors measure your heart rhythm using a device that is outside of your body and are usually used for short periods of time. For an implantable loop recorder, your doctor will place the device under your skin. The recorder transmits data to your doctor’s office. Implantable loop recorders may be worn for longer periods of time and may help your doctor figure out why you are having palpitations or fainting spells, especially if these symptoms do not happen very often.
- An electrophysiology study (EPS), which is performed by an EPS cardiologist, measures the electrical activity of your heart. The doctor threads a wire through a blood vessel to your heart. The wire electrically stimulates your heart and triggers any underlying arrhythmia if you have one. If you have another condition that may raise your risk, an EPS can help your doctor find out your risk of developing arrhythmias. An EPS also allows your doctor to test whether a treatment, such as medicine, will stop the problem.
- Tilt table testing may help find the cause of fainting spells. You lie on a table that moves from a lying-down position to an upright position. The change in position may cause you to faint. Your doctor watches your symptoms, heart rate, EKG reading, and blood pressure throughout the test.
- Genetic testing can check whether you have a type of arrhythmia that is caused by specific . This test is important when one or more of your close relatives has an arrhythmia caused by the same gene or had cardiac arrest.
- Heart imaging tests, such as computed tomography (CT) scans or cardiac magnetic resonance imaging (MRI), may check the structure of your heart chambers, show how well your heart is working, look for evidence of scar tissue in your heart muscle, or sometimes may look at your heart arteries.