Atrioventricular nodal reentry tachycardia (AVNRT)

Overview

Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia. People with AVNRT have episodes of an irregularly 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.

Diagnosis

Tests and procedures used to diagnose AVNRT may include:

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

Your health care provider 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 the heart activity is monitored
• Electrophysiological study and cardiac mapping, which can reveal the precise location of the irregular heartbeat (arrhythmia)

Treatment

Most people with AVNRT don't need medical treatment. However, if you have prolonged or frequent episodes, your health care provider 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 health care provider 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 typical heart rhythm.
• Medications. If you have frequent episodes of AVNRT, your health care provider may prescribe medication to control your heart rate or restore a normal heart rhythm.
• Catheter ablation. In this procedure, a health care provider threads one or more catheters through the blood vessels to the 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 the arrhythmia.