Diagnosis

To diagnose bradycardia, a health care provider will usually perform a physical exam and listen to your heart with a stethoscope. He or she may ask you questions about your symptoms and medical history.

Your health care provider may recommend tests to check your heart rate and see if you have a heart problem that can cause bradycardia. Blood tests may be done to check for other conditions that can cause slow heartbeats, such as an infection, an underactive thyroid (hypothyroidism) or an electrolyte imbalance.

Tests

An electrocardiogram (ECG or EKG) is the main test used to diagnose bradycardia. An ECG measures the electrical activity of the heart. Sticky patches (electrodes) are placed on the chest and sometimes the arms and legs. Wires connect the electrodes to a computer, which displays the results. An ECG can show if the heart is beating too slow, too fast or not at all.

Because an ECG can't detect bradycardia unless the slow heartbeat occurs during the test, your health care provider might recommend a portable ECG device. Portable ECG devices include:

• Holter monitor. Carried in a pocket or worn on a belt or shoulder strap, this device records the heart's activity continuously for 24 hours or longer.
• Event recorder. This device is similar to a Holter monitor, but it records only at certain times for a few minutes at a time. It's worn longer than a Holter monitor, typically 30 days. You generally push a button when you feel symptoms. Some devices automatically record when an irregular heart rhythm is detected.

An ECG may be done with other tests to understand how bradycardia affects you. These tests include:

• Tilt table test. This test may help your health care provider better understand how your bradycardia causes fainting spells. As you lie flat on a special table, the table is tilted as if you were standing up. A tilt test is done to see if a change in position causes fainting.
• Stress exercise test. An ECG may be done to monitor your heart's activity while you ride on a stationary bicycle or walk on a treadmill. If you have difficulty exercising, a drug may be given to stimulate the heart in a way that's similar to exercise.

A sleep study may be recommended if your health care provider thinks that repeated pauses in breathing during sleep (obstructive sleep apnea) are causing bradycardia.