Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia. People with AVNRT have episodes of an abnormally fast heartbeat (more than 100 beats per minute) that often start and end suddenly. The episodes are due to an extra pathway — called a reentrant circuit — located in or near the AV node that causes the heart to beat prematurely.

AVNRT tends to occur more often in young women, but it can affect anyone.

Tests and procedures used to diagnose AVNRT may include:

• Blood tests to check thyroid function, heart disease or other conditions that may trigger your abnormal heartbeat
• Electrocardiogram (ECG) to measure the electrical activity of your heart and measure the timing and duration of each heartbeat
• Holter monitor, which is a portable ECG device designed to record your heart's activity as you perform your normal everyday activities
• Echocardiogram, which uses sound waves to produce images of your heart's size, structure and motion

Your doctor might also try to trigger an episode with other tests, which may include:

• Stress test, which is typically done on a treadmill or stationary bicycle while your heart activity is monitored\
• Electrophysiological study and cardiac mapping, which allow your doctor to see the precise location of the irregular heartbeat (arrhythmia)

Most people with AVNRT don't need medical treatment. However, if you have prolonged or frequent episodes, your doctor may recommend:

• Vagal maneuvers. You may be able to stop an episode of atrioventricular nodal reentry tachycardia by using particular maneuvers that include holding your breath and straining, dunking your face in ice water, or coughing.
• Cardioversion. If particular movements, such as coughing or straining, don't work, your doctor may recommend cardioversion. This treatment can be done using medications or by delivering a shock to your heart through paddles or patches on your chest. The shock affects the electrical signals in your heart and can restore a normal heart rhythm.
• Medications. If you have frequent episodes of AVNRT, your doctor may prescribe medication to control your heart rate or restore a normal heart rhythm.
• Catheter ablation. In this procedure, your doctor threads one or more catheters through your blood vessels to your heart. Sensors at the tip of the catheter use heat energy (radiofrequency) or extreme cold (cryoablation) to scar a small area of heart tissue and block the faulty signals that are causing your arrhythmia.