Many arrhythmias happen only once in a while. This can make them very hard to diagnose. Your doctor will use a series of questions and tests to diagnose your arrhythmia. These include personal and family medical histories, a physical examination, and a series of diagnostic tests. Some of these tests are designed to trigger an arrhythmia so your doctor can observe the event.
You will need to describe your symptoms in as much detail as possible. Your doctor will want to know if you feel your heart racing or fluttering, if you feel dizzy or lightheaded, and if you have shortness of breath. You may be asked when these symptoms occur and how often.
You doctor will also ask about any other medical conditions you may have. Heart disease, diabetes, high blood pressure, and thyroid problems can contribute to an arrhythmia. Some medications can also cause arrhythmia, so be sure to tell your doctor about all medications you are taking. This includes over-the-counter medicines as well as vitamins, minerals, and herbal supplements. Your physical habits, whether you smoke, and consumption of alcohol, caffeine, and drugs are also relevant. So is your level of stress.
Your doctor may also ask about your family’s medical history. He or she may want to know if anyone in your family has arrhythmias, heart disease, or high blood pressure; has died suddenly; or has other illnesses or health problems.
During the physical exam, your doctor will listen to your heart rate and rhythm. He or she might do one or more of the following:
- listen for a heart murmur, an unusual sound or extra sound heard during a heartbeat
- check your pulse to measure your resting heart rate
- check for swelling in the legs and feet, which can be a sign of heart failure or heart disease
- order a series of blood tests to check for indicators of heart disease or a thyroid problem
After this initial physical exam, your doctor may request a few diagnostic tests and procedures to either confirm or disprove an arrhythmia diagnosis.
Doctors use a variety of tests to help diagnose an arrhythmia. Some involve monitoring your heart over a period of time. This way, when an arrhythmia occurs, it can be recorded. Some try to trigger an arrhythmia while the doctor is present to observe. Others look for other conditions that are known to cause arrhythmias.
An ECG is the most common test used to diagnose an arrhythmia. During an ECG, electrodes that detect the electrical activity of your heart record the timing and duration of your heartbeat. This test can show how quickly the heart is beating and its rhythm, as well as the strength and timing of the electrical signals as they pass through the heart.
An ECG is conducted in a hospital or doctor’s office, but in some cases, your doctor may want to monitor your heart’s electrical activity for an extended period. (Your symptoms may be so sporadic that you are unable to stay in a doctor’s office or hospital long enough to detect one.) In that case, you may be asked to wear a portable ECG, known as a Holter monitor. This monitor can be worn for several days. It records your heart’s activity continuously.
Like a Holter monitor, an event monitor will record your heart rate while allowing you to carry on with your routine. The event ECG monitor only begins recording when you start having symptoms of an arrhythmia. (In most cases, you tell the monitor when to begin recording.) This will allow your doctor to see your heart’s rhythm only at the time of the symptoms.
Transthoracic Echocardiogram (TTE)
An echocardiogram uses noninvasive sound waves to produce an image of your heart so your doctor can see how the chambers and valves are functioning. This image is produced by placing a sonography probe on the chest and taking several pictures of the heart through the chest wall.
Transesophageal Echo (TEE)
While a TTE sends ultrasound waves through the front of your body to produce an image, a TEE sends ultrasound waves from your esophagus. This allows your doctor to see the back of your heart and to better visualize the valvular structures of the heart. To do this test, however, your doctor will have to sedate you so he can run a tube down your throat to best visualize the heart.
CT Scan or MRI
Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI) tests are noninvasive scans that can detect structural heart problems which may predispose you to developing arrhythmias. In a CT, you lie on a table inside a round machine. The machine rotates around your body and collects X-rays of your heart and chest. In an MRI, you lie on a table inside a tube-shaped machine. A magnetic field aligns atomic particles in your body’s cells, producing signals that create images of your heart.
Your doctor may want to check the levels of electrolytes—such as potassium, sodium, and calcium—present in your blood. He or she may also want to check your thyroid hormone. If any of these levels are too low or too high, they can cause arrhythmias.
Some arrhythmias are easier to detect when your heart is working harder than when it is at rest, such as during exercise. Your doctor may have you exercise in a controlled environment to increase your heart rate. During your period of activity, your heart is monitored by an ECG. If you’re unable to exercise or have a difficult time doing so, your doctor may give you a pill that will stimulate your heart to achieve heart rate levels similar to that of exercise.
Tilt Table Test
If one of your symptoms is fainting, your doctor may use a tilt table to check for a possible arrhythmia. In this test, you lie flat on a table. The table is then tilted 90 degrees to a standing position. Your doctor will watch your heart, nervous system, blood pressure, and ECG readings as the table moves you up and down from flat to standing.
A thin, flexible tube (called a catheter) is inserted into a blood vessel either in your arm, upper thigh (groin), or neck. Using a special dye and X-ray machine, your doctor can watch the flow of blood through your heart and blood vessels, looking for any possible blockages or leaks.
Electrophysiological Testing and Mapping
Much like coronary angiography, electrophysiological testing and mapping uses a thin, flexible catheter to map the inner workings of your heart. But in this case, electrodes on the catheter stimulate the heart, and a machine records the spread of these impulses as they travel through the heart. This helps your doctor locate possible impulse blockages or short circuits.
Implantable Loop Recorder
An implantable loop recorder is placed under the skin of your chest, where it can detect and record any abnormal heart rhythm. This device is particularly helpful if your symptoms don’t occur frequently.