Arrhythmias may be identified during routine health check-ups, during testing after symptoms have appeared, or during an evaluation of heart health.

The most common method of checking the heart's electrical activity is with an ECG. A healthy heart with normal rhythms will create a specific pattern on the ECG. Abnormal rhythms of the heart will change the appearance of this pattern. Changes in certain areas of the ECG pattern will also show what specific areas of the heart are affected or damaged.

Heart Monitoring

Some arrhythmias may only appear when the heart is working hard. An exercise stress test is an ECG during physical activity. The test is used to look for an appropriate response to exercise, appearance of abnormal rhythms or events during activity, and ability for heart to recover after activity. People who cannot exercise may be given IV medication that simulates the effects of physical exertion on the heart.

Most arrhythmias are not constant. They may not occur during testing in a care center. Your doctor may recommend a portable device that will monitor your heart rhythm over a long period of time during everyday activities. Portable heart monitoring can be done with:

  • Holter monitor —A small machine is belted around your waist and will record your heart rhythm over a period of 24 hours or more.
  • Transtelephonic monitoring —Instead of a Holter monitor, you may take home a device that allows you to send your ECG recording over the telephone at the moment you feel symptoms of an arrhythmia.
  • Implantable loop recorder —If a longer period of recording is necessary, a small rectangular recording device may be surgically implanted underneath the skin of the chest. If the ECG-like information recorded falls within certain normal limits, the device erases the data. Abnormal heart rhythms are retained until your doctor retrieves the information.

Tests to Look for Causes

If you are diagnosed with an arrhythmia, your doctor may want other tests to help determine if there is an underlying cause. This may include imaging tests, which can evaluate your heart, blood vessels, and surrounding structures for any loss of function or damage. Imaging tests may include:

  • Cardiac catheterization and coronary angiography —To help detect obstruction in the arteries of heart and assess heart function.
  • Chest x-ray —To look for heart enlargement or congestion in the lungs.
  • Nuclear scanning —To visualize the blood supply to the heart. Areas with poor blood supply can potentially generate abnormal rhythms.
  • CT and MRI angiography —To highlight blood vessels and see where blockage occurs.
  • Echocardiogram —Ultrasound is used to evaluate the size, shape, and motion of the heart. A more specialized version uses the Doppler effect to visualize blood flow.

Other tests to look for potential causes or contributing factors include:

  • Blood and urine tests —To evaluate your overall health, and fluid and electrolyte levels. These tests can also detect problems with your kidneys or liver.
  • Tilt table testing —This test is usually ordered for people with fainting episodes. Your heart rate and blood pressure are closely monitored while you are first lying flat on a table and then when the table is tilted. It may help determine the cause of your fainting.
  • Electrophysiologic testing —This is an invasive test that is generally reserved for complex rhythm disturbances or to assess treatment. The test is done by passing an electrode through the blood vessels to the heart. The electrode can provide information on electrical activity of the heart and the spread of electrical impulses through the heart. It may also be used during invasive procedures to guide treatment to help manage heart problems.

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