AV nodal reentrant tachycardia (AVNRT) is one of the most common types of supraventricular tachycardia. It occurs when a short-circuit forms within or very close to the atrioventricular (AV) node, causing the heart to suddenly beat very fast.
Although AVNRT can feel dramatic and frightening, it is usually not dangerous. Many people experiencing AVNRT have otherwise normal hearts and long-term outcomes are excellent with appropriate management.
How AVNRT Happens
The AV node normally acts as a gatekeeper, briefly slowing electrical signals as they travel from the atria to the ventricles. In AVNRT, there are two electrical pathways within or near the AV node: one that conducts signals quickly and another that conducts more slowly.
Under certain conditions, an electrical impulse can begin to circulate between these two pathways instead of moving forward normally. This creates a rapid, self-sustaining electrical loop, causing the heart rate to suddenly accelerate—often to 150–220 beats per minute.
This reentry mechanism explains why AVNRT typically starts and stops abruptly.
What AVNRT Feels Like
AVNRT episodes often begin without warning and may end just as suddenly. The sudden onset is a key feature that helps distinguish AVNRT from other causes of palpitations.
Common symptoms include:
- Sudden racing heartbeat
- Palpitations with a regular, rapid rhythm
- Chest tightness or discomfort
- Shortness of breath
- Lightheadedness or dizziness
Some people also notice neck pulsations caused by near-simultaneous contraction of the atria and ventricles.
Why AVNRT Occurs
AVNRT is usually related to the heart’s electrical wiring rather than structural heart disease. Many people are born with the dual AV nodal pathways that make AVNRT possible, but symptoms may not appear until adulthood.
Triggers can include stress, caffeine, alcohol, lack of sleep, or sudden changes in heart rate. In many cases, episodes occur without a clear trigger.
Is AVNRT Dangerous?
For most people, AVNRT is not life-threatening. The heart rhythm is fast but organized, and serious complications are rare.
However, frequent or prolonged episodes can significantly affect quality of life. In rare cases, very rapid heart rates may cause fainting or worsen symptoms in people with other heart conditions.
Because AVNRT is highly treatable, evaluation is recommended when episodes are recurrent or disruptive.
How AVNRT Is Diagnosed
Diagnosis is based on documenting the rhythm, usually with an electrocardiogram during an episode. Because episodes may be intermittent, ambulatory rhythm monitoring is often used.
In some cases, an electrophysiology study is performed to confirm the diagnosis and precisely identify the reentrant circuit. This is typically done when catheter ablation is being considered.
Treatment Options for AVNRT
Treatment of AV nodal reentrant tachycardia (AVNRT) depends on how often episodes occur, how long they last, and how much they interfere with daily life. Management is generally divided into acute episode treatment and long-term rhythm control.
Acute Episode Management
Some AVNRT episodes can be terminated using vagal maneuvers, which stimulate the vagus nerve and temporarily slow electrical conduction through the AV node. By slowing conduction, these maneuvers can interrupt the reentrant circuit responsible for the tachycardia.
Commonly used vagal maneuvers include:
- Valsalva maneuver: forceful exhalation against a closed airway
- Modified Valsalva maneuver: exhalation followed by lying flat and raising the legs
- Cold facial stimulation: mainly used in younger patients
When performed correctly, these maneuvers can stop an episode within seconds in some patients. However, they are not effective for everyone.
If vagal maneuvers fail or symptoms are severe, intravenous medications are used in a medical setting.
The most commonly used drug is adenosine, which briefly blocks conduction through the AV node and terminates the tachycardia. In selected cases, beta blockers or calcium channel blockers may also be used for acute control.
Long-Term Treatment Options
Long-term treatment is considered when episodes are recurrent, prolonged, or significantly affect quality of life.
Medication Therapy
Medications that slow conduction through the AV node can reduce the frequency or severity of AVNRT episodes. These drugs may help control symptoms but do not eliminate the underlying electrical circuit responsible for the arrhythmia.
For this reason, medication therapy is usually aimed at symptom reduction rather than permanent cure.
Catheter Ablation
Catheter ablation is the most effective and definitive treatment for AVNRT.
During the procedure, thin catheters are inserted through a vein in the groin or arm and advanced to the heart. Detailed electrical mapping is performed to identify the slow pathway involved in the reentrant circuit. This pathway is then carefully modified using controlled energy, interrupting the circuit while preserving normal AV node function.
When performed in experienced centers:
- Success rates are very high
- Recurrence is uncommon
- Most patients no longer require long-term medication
For many individuals, catheter ablation offers a permanent solution and restores a normal heart rhythm.
Summary of Treatment Approach
- Infrequent and mild episodes. observation or medication
- Recurrent or symptomatic episodes. catheter ablation is often preferred
Treatment decisions are individualized and made in close discussion with the patient.
Living With AVNRT
Living with AVNRT can be frustrating due to the sudden and unpredictable nature of episodes. Education is key—understanding that the condition is benign and highly treatable helps reduce anxiety.
With appropriate treatment, most people with AVNRT can lead completely normal, unrestricted lives.
In Summary
AV nodal reentrant tachycardia is a common and usually benign cause of sudden rapid heart rate. It results from a small electrical loop within or near the AV node. While episodes can be uncomfortable, AVNRT is highly treatable, and catheter ablation offers an excellent chance of permanent resolution in many patients.
Reference: AVNRT
