Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

What is AVNRT?

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common kind of supraventricular tachycardia (SVT) due to an extra electrical pathway. SVT is a heart condition that makes the heart suddenly beat much faster than normal.

A normal heartbeat is about 60 to 100 beats per minute when a person is at rest. But a person with AVNRT experiences sudden episodes of an abnormally fast heartbeat, often 140 to 280 beats per minute.

AVNRT and SVT are types of arrhythmias, which is any type of irregular or abnormal heartbeat.

Who might get AVNRT?

AVNRT can affect anyone, is more common in women than men and can even occur in young, otherwise healthy adults.

What causes AVNRT?

Electrical signals control the rate and rhythm of your heart. They start in the sinoatrial (SA) node, a special group of muscle fibers in your heart’s upper right chamber (atrium). The SA node is your heart’s natural pacemaker.

In a healthy heart, an electrical impulse from the sinoatrial node makes the two upper chambers (the atria) contract (pump). The impulse then travels through pathways to the atrioventricular (AV) node and into your heart’s two lower chambers (the ventricles). The AV node acts as a gate between the upper chambers and the lower chambers.

That is how a normal heart moves blood through the chambers and into the rest of your body. But a problem with your heart’s electrical system can cause an abnormal heartbeat (irregular, too fast or too slow). That’s called arrhythmia.

SVT is one type of arrhythmia, and AVNRT is the most common type of SVT.

In AVNRT, a premature contraction occurs. The heart has a small extra pathway near the AV node, called a reentrant circuit. The early contraction can make the electrical impulse enter the circuit and circle around. That can cause sudden sustained fast heartbeats.

Some families may have several members with the condition, suggesting that AVNRT can be inherited, but research has not yet found a genetic explanation.

What are the symptoms of AVNRT?

AVNRT happens in episodes, meaning the rapid heartbeat comes and goes. A person with the condition can have symptoms for years before getting a diagnosis.

Common signs include:

• Discomfort in the neck or chest.
• Dizziness.
• Fast heartbeat (140 to 280 beats per minute).
• Palpitations.
• Polyuria, excessive amounts of urine (pee).
• Shortness of breath.

In rare, severe cases, AVNRT can cause more serious symptoms and complications such as:

• Chest pain.
• Confusion.
• Fainting (syncope).
• Low blood pressure (hypotension).
• Shock.

What do AVNRT palpitations feel like?

People with AVNRT have described the heart palpitations as:

• Flip-flopping.
• Fluttering.
• Fullness in the neck or throat.
• Pounding.
• Racing.

How is AVNRT diagnosed?

To diagnose AVNRT or another arrhythmia, a healthcare provider will perform:

• Medical history: This involves questions about medical problems you’ve had, recent symptoms and any medications or other substances you use.
• Physical exam: The healthcare provider will measure your vital signs, including breathing rate, blood pressure and heart rate. They will also listen to your heart.
• Electrocardiogram: An electrocardiogram (EKG) measures the electrical activity in the heart, including the timing and duration of each heartbeat. This can be used to help confirm the diagnosis during an acute episode.

The healthcare provider may also order other tests to assess your heart:

• Blood tests to identify any other problems that might be affecting your heart.
• Echocardiogram(echo),which produces images of your heart to detect any problems with its structure or pumping action.
• Holter monitor, or other ambulatory monitor, a device you wear for a few days to monitor heart rhythm as you go about your daily routine. This type of device can detect arrhythmia episodes that did not occur during the EKG.
• Exercise stress test, which monitors your heart’s activity while you exercise on a treadmill or stationary bike.
• Electrophysiological (EP) study and cardiac mapping is an invasive procedure that can be used to determine the exact etiology and location of the arrhythmia.

How is AVNRT treated?

Many people with AVNRT don’t need treatment. But your healthcare team may recommend treatment if you:

• Are at risk for serious complications.
• Experience symptoms that interfere with your daily life, such as fainting.
• Have frequent or prolonged episodes of AVNRT.

Several treatment strategies are available:

• Vagal maneuvers: You may be able to stop an episode of AVNRT with simple strategies at home. Examples include coughing, holding your breath or dipping your face in cold water.
• Electrical cardioversion: Cardioversion delivers an electrical shock to the heart via paddles or patches on your chest. The procedure can restore a normal heart rhythm.
• Medications: Several medications can regulate heart rate and rhythm. Examples include adenosine injection, antiarrhythmic drugs, calcium channel blockers and beta-blockers.
• Catheter ablation: Catheter ablation creates scar tissue in heart muscle, which can block faulty electrical signals and cure certain types of arrhythmia, such as AVNRT.

What is the outlook for people with AVNRT?

In rare instances, AVNRT can result in serious complications, such as sudden cardiac arrest. But it is not life-threatening for the vast majority of people.

How can I reduce my risk?

There’s no proven way to prevent AVNRT. But if you have the condition, you may notice that certain things are more likely to lead to AVNRT episodes.

If you avoid triggers, you may be able to reduce the frequency of episodes. Triggers may include:

• Alcohol.
• Caffeine.
• Certain types of exercise (talk to your healthcare provider).
• Herbal supplements.
• Recreational drugs.
• Smoking or using tobacco products.
• Stress.

How do I take care of myself with AVNRT?

Certain strategies may help you control AVNRT episodes, including:

• Don’t use any over-the-counter medications or supplements without checking with your healthcare provider first.
• Have regular follow-up visits with your healthcare provider, such as a cardiologist (heart specialist).
• Take all of your medications as directed.
• Track and avoid triggers that tend to set off AVNRT episodes.
• Tell your healthcare provider if you notice any changes in your symptoms. For example, are episodes worse now than they used to be? Do they happen more often?

Can I exercise with AVNRT?

Exercise is an important part of heart health, and most people with AVNRT can exercise. But talk to your healthcare provider about whether you should restrict certain types of activity.

When should I seek medical attention for AVNRT?

If you have AVNRT, seek medical attention if you experience:

• Chest pain.
• Episodes that last a long time or become more frequent.
• Lightheadedness, dizziness or fainting.
• Shortness of breath.