Arrhythmia Tests

Your doctor may order heart-monitoring tests to determine the severity of your palpitations. Tests fall into two general categories.

"Passive" tests monitor your regular heart activity. These include the electrocardiogram (ECG), holter monitor, ECG monitor (portable), ECG monitor (implantable), and echocardiogram.

"Active" tests aim to provoke the arrhythmia so it can be studied as it happens. These include:the stress test, tilt table test, and electrophysiologic testing and mapping

Passive tests

Here are the more common forms of passive tests used to monitor heart rhythms:

• Electrocardiogram (ECG): Electrodes taped to your skin detect electrical activity of your heart, recording it as waves that represent the electrical forces in different parts of the heart. Different rhythms produce different patterns of waves that can help to diagnose arrhythmias. An ECG is not painful and usually takes just a few minutes

• Holter monitor: This is a portable ECG monitor that you wear to provide your doctor with a continuous record of heart rhythms during your daily activities. It's commonly used if you have frequent palpitations. It's typically worn for 24 hours. Like a regular ECG, it reads electrical activity through electrodes taped to the skin. They're attached to a small battery-operated monitor that you carry with you or wear in a pouch around your neck. It's not painful and requires no special preparation, but you won't be able to take a shower or get the monitor wet during the testing period. Your doctor will also ask you to note the time and nature of any symptoms you experience while wearing the monitor. That information will be compared with the ECG's results.

• ECG monitor (portable): This is another kind of portable ECG, also known as an event monitor. Unlike the Holter monitor, it's used if you have infrequent palpitations. You wear it for longer periods and activate it only when you experience symptoms. When you feel your typical symptoms, you push a button and an ECG strip of the preceding few minutes and following few minutes is recorded for later playback and analysis. The unit itself is small enough to clip to your belt, and it has sticky sensors that you can remove when you shower or get wet.

• ECG monitor (implantable): This monitor, the size of the little finger, is placed under the skin in the upper part of the chest and continuously records the ECG for up to 15 months. It can be activated by placing a programmer over the skin, or automatically if an abnormal heart rate is detected, and records the preceding few minutes and following few minutes for later playback and analysis. This type of recorder does not require electrodes taped to the skin and is not affected by showering or perspiration.

• Echocardiogram: An echocardiogram, or "echo," uses sound waves (ultrasound) to make images of your heart or to analyze blood flow. The sound waves are sent into your body from a small, hand-held device called a transducer, and then the sound waves are reflected back from internal structures, returning to the transducer. Different forms of echocardiography are used for different purposes. One form, for example, is useful for measuring the exact size of various heart structures, such as heart chambers. Another form shows how parts of the heart work when they move.

• Transesophageal echocardiogram (TEE): A transesophageal echocardiogram is similar to a regular echo, but patients swallow a thin tube with an ultrasound sensor on it to get a better picture of the heart. This procedure can be uncomfortable so you'll probably be sedated beforehand and will get a local anesthetic in your mouth and throat to help you swallow the tube, which is later removed.

Active tests

In some cases, your doctor will want to provoke an arrhythmia so that he or she can study it as it happens. In that case, one of several tests may be used:

• Stress test: This test is a general screening tool to measure the effect of exercise on your heart and to detect heart and coronary artery disease. Because some arrhythmias are influenced by exercise, the test is used to capture those abnormal rhythms where your doctor can read them. Usually you'll exercise on a treadmill or a stationary bicycle while connected to an ECG (electrocardiogram).

• Tilt-table test: If you've had fainting spells (syncope), your doctor may recommend this test to simulate the action of getting up from a prone position. Your heart rate and blood pressure are recorded while you are lying down on the table. The table is then tilted, just as if you were standing up. Your doctor measures how your heart reacts to the change in position. A catheter may be placed in an artery to monitor blood pressure during the test.

• Electrophysiologic testing and mapping (EP): An electrophysiology study can determine the presence and cause of abnormal heart rhythm and localize its origin in the heart. Typically, it takes about four hours and must be done after a fast. EP studies involve X-ray equipment, computer monitors, and equipment used to record the heart's electrical activity. The patient has an intravenous (IV) catheter in the arm to give any medication needed during the procedure. He or she may receive mild sedation for the procedure (children under 12 usually receive general anesthesia).

An electrode catheter—a thin, flexible tube with an electrode at the end—may be put in through a neck vein, while others are put in a vein in one or both legs. They're threaded to various parts of the heart to record impulses in different regions of the heart and can also measure how your heart conducts the impulse from one area to another. This helps your doctor construct a "map" of your heart's electrical system. The electrodes may also be used to stimulate or calm arrhythmias and to test the effectiveness of different treatments. The risk of complications from this test is relatively low, occurring in about 1 to 2 percent of the procedures, and is mostly related to inserting the catheters in your blood vessels. The doctor performing the test will discuss possible complications with you.