How is a cardiac arrhythmia diagnosed?

Arrhythmias can be hard to diagnose, especially the types that only cause symptoms every once in a while. Doctors use several methods to help diagnose arrhythmias, including medical and family histories, physical exam, and diagnostic tests and procedures.

Specialists involved
Doctors who specialize in the diagnosis and treatment of heart diseases include:

• Cardiologists.
• Pediatric cardiologists.
• Electrophysiologists: These doctors are cardiologists or pediatric cardiologists who specialize in arrhythmias.

Medical histories
To diagnose an arrhythmia, your doctor may ask about your signs and symptoms. He or she may ask about what symptoms you're having, whether you feel fluttering in your chest, and whether you feel dizzy or lightheaded.

Physical exam
Your doctor will listen to the rate and rhythm of your heart and for a heart murmur. He or she also will:

• Check your pulse to find out how fast your heart is beating
• Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
• Look for signs of other diseases, such as thyroid disease, that could be causing the problem

Diagnostic tests and procedures

EKG (Electrocardiogram)
An EKG is the most common test used to diagnose arrhythmias. An EKG is a simple test that detects and records the heart's electrical activity.

Holter and event monitors
A Holter monitor records the heart's electrical signals for a full 24- or 48-hour period. You wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.

Other tests used to diagnose arrhythmias are:

• Blood tests
• Chest x ray
• Stress test
• Electrophysiology study (EPS)
• Tilt table testing
• Coronary angiography
• Implantable loop recorder

This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.

Diagnosis of an arrhythmia can be done through an EKG or through heart monitors.

Doctors usually administer an electrocardiogram (ECG) to measure the electrical activity of the heart. This technology creates a graphic representation of the heart's electrical activity. Some people benefit from more prolonged monitoring to catch infrequent arrhythmias.

Doctors have pioneered advances in arrhythmia diagnosis and have developed a technology called signal-averaged electrocardiogram. This method analyzes the electrical details of hundreds of heartbeats. Taken together, the details can identify even small irregularities.

Doctors use diagnostic electrophysiology, a minimally invasive technology to pinpoint the area of tissue causing an arrhythmia. The doctor sends and receives signals to the heart to create a map of the damage by threading a flexible tube attached to a monitoring electrode through a blood vessel in the groin or neck and into the heart.

A variety of heart-monitoring tests are used to diagnose arrhythmia. These tests include electrocardiogram (ECG) monitors that can be worn during everyday activities or when arrhythmia symptoms occur to record your heartbeat. If your arrhythmia is triggered by exercise, your doctor may use a stress test to monitor your heart rate. Electrophysiologic testing and mapping allows your doctor to stimulate the irregular heart beat, and then map your heart to find the location responsible for arrhythmia. In addition to these tests, your doctor may also test for an underlying cause, such as an electrolyte imbalance or thyroid disorder.

A cardiac arrhythmia such as atrial fibrillation can be diagnosed in different ways. In addition to reviewing your medical history and symptoms, and performing a thorough physical exam, a physician may recommend one of the following diagnostic tests to examine the heart's structure or activity:

• An electrocardiogram or EKG
• An echocardiogram
• A Holter monitor
• An event monitor

Doctors diagnose cardiac arrhythmia with monitors. Longer-term monitors and implants can also help diagnose arrhythmias.

Cardiac arrythmias, or cardiac rhythm disturbances, are usually diagnosed based on the person's symptoms, medical history, risk factors, a physical exam, and with results from tests and procedures.

During a physical examination, the doctor will check the person's heart rate and rhythm, together with the pulse. If the doctor believes there may be a cardiac rhythm disturbance, he or she likely will order an electrocardiogram (EKG) for confirmation.

There also is a more advanced version of an EKG where the doctor may ask the person to wear an “event” (or “Holter”) monitor. This is a portable device that is the size of a smartphone or smaller and can be worn under clothing, similar to an exercise heart rate monitor. This device will relay information back to the doctor and identify any abnormal rhythms that might happen intermittently, but not all of the time. The monitor usually is worn for 24 to 48 hours to get the required information.

The doctor also may recommend one or more of the following:

• echocardiogram (echo)
• chest x-ray
• blood tests
• stress test
• coronary angiography

If a family doctor discovers the heart rhythm problem, the person likely will be referred to a cardiologist (general heart specialist) or an electrophysiologist (heart rhythm specialist).

This content originally appeared online in "The Patient Guide to Heart, Lung, and Esophageal Surgery" from the Society of Thoracic Surgery.