Atrioventricular (AV) nodal reentrant tachycardia (AVNRT) is an irregular heart rhythm that can cause excessively fast heart rates. Though not usually serious, early diagnosis can help prevent severe symptoms and complications.
AVNRT is a type of irregular heart rhythm (arrhythmia). It’s also a type of tachycardia, which is an irregularly fast heart rate.
People with AVNRT may experience a sudden rapid heart rate upward of 140 to 280 beats per minute . They also often have other cardiovascular-related conditions. However, getting an early diagnosis usually leads to a favorable outlook for people with AVNRT.
If you’ve recently received an AVNRT diagnosis or are concerned you might have this condition, read on to learn more about how it develops, some of the common signs and symptoms, and how a doctor will diagnose and treat it.
What causes AV nodal reentrant tachycardia?
AVNRT develops when the AV node in the right atrium of your heart also has a reentrant circuit that can cause extra contractions. This results in an unusually high heart rate.
AVNRT belongs to an umbrella group of conditions called paroxysmal supraventricular tachycardia (PSVT) , which itself is a subset of supraventricular tachycardia (SVT) . SVTs affect the upper atria of your heart and can cause heart rates over 100 beats per minute .
Experts consider AVNRT the most common type of PSVT, making up about 60% of all cases. It’s most common in females. Symptoms usually appear by your 20s but can sometimes develop later in life.
Some of the possible causes and risk factors for PSVTs like AVNRT include:
AVNRT vs. AVRT
AV reciprocating tachycardia (AVRT) is the fourth most common type of SVT in adults over 20 years of age. It’s also the most common form of SVT in childhood due to its association with the congenital condition Wolff-Parkinson-White syndrome.
AVNRT and AVRT can cause similar symptoms. The key difference is that AVRT is due to an additional pathway that can lead to irregular heart rhythms. An electrocardiogram (ECG) can help doctors differentiate between the two.
What are the symptoms of AV nodal reentrant tachycardia?
PSVTs, including AVNRT, can decrease blood flow throughout your body because the heart doesn’t have a chance to fill with blood between beats. For some people, this may result in symptoms.
The “paroxysmal” in PSVT refers to the fact that its symptoms and effects may come and go without warning. However, some people may also notice specific symptom triggers , such as stress, exercise, or periods of rest.
Some of the most common symptoms of AVNRT include:
How do doctors diagnose AV nodal reentrant tachycardia?
First, a doctor will ask about your personal and family health history, particularly any heart-related conditions. They’ll also conduct a physical exam, which includes taking a blood pressure reading and listening to your heart with a stethoscope .
An ECG is important in diagnosing AVNRT. However, since the signs and symptoms of AVNRT are sporadic like other types of PSVTs, a doctor may require multiple readings or recommend a home heart monitor .
These diagnostic tests will also help a doctor rule out other possible causes of your symptoms, such as coronary artery disease and heart failure.
ECG findings in AV nodal reentrant tachycardia
An ECG can help a doctor measure the electrical activity in your heart. It may confirm that you have AVNRT if your heart rate is 140 to 280 beats per minute , along with a QRS complex of less than 120 milliseconds.
What’s the treatment for AV nodal reentrant tachycardia?
The exact treatment plan for AVNRT will depend on the severity of your condition. Options may include:
- Vagal maneuvers: A doctor may recommend guided exercises, such as blowing through your nostrils while holding your nose, to help control the vagus nerve from increasing your heart rate.
- Adenosine: A doctor may recommend this intravenous (IV) medication as a first-line treatment for AVNRT without coronary artery disease or severe lung diseases.
- Other IV medications: If adenosine doesn’t improve AVNRT, a doctor may recommend other antiarrhythmic medications, such as beta-blockers or calcium channel blockers .
- Catheter ablation: This involves the insertion of a catheter through your arteries and the use of energy to stop the heart from receiving irregular signals from the AV node. Experts think that catheter ablation is 95% effective in treating AVNRT.
- Electrical cardioversion: Doctors reserve this procedure for severe cases of AVNRT that have led to severe tachycardia along with chest pain, low blood pressure, or shock.
What’s the outlook for people with AV nodal reentrant tachycardia?
The overall outlook for people with AVNRT is positive, particularly with early diagnosis and treatment. However, a lack of diagnostic testing and treatment could increase the risk of complications associated with this condition.
Without treatment, you may also be more likely to experience symptoms such as dizziness, fainting, and fatigue. Such symptoms are also associated with severe cases of AVNRT.
Frequently asked questions
Below are answers to some frequently asked questions about AVRNT.
Is AVNRT dangerous?
AVNRT isn’t typically dangerous, but it can be in rare cases. A delayed diagnosis may increase your risk of complications.
Ongoing treatment is key to regulating AVNRT and preventing complications.
Is AVNRT hereditary?
It’s not clear if AVNRT is hereditary, though some research suggests that it might be.
Although SVT is the most common childhood arrhythmia, it can also first develop in middle-aged adults. The age of onset may suggest that AVNRT could be hereditary for some people but not all. More research is needed in this area.
What’s the difference between SVT and AVNRT?
AVNRT is a subtype of SVT. As a form of tachycardia, SVT affects your heart’s AV node and can cause your heart rate to be 160 beats per minute or higher. AVNRT is also a PSVT because symptoms can come and go without any clear triggers.
Takeaway
AVNRT is a type of PSVT that usually develops by early adulthood. However, due to its association with other heart conditions, some people develop AVNRT much later in life. The signs of an increased heart rate are sporadic, and not everyone experiences symptoms.
Although experts don’t consider AVNRT life threatening, the condition can become more severe over time without diagnosis and treatment. Consider speaking with a doctor if you have unexplained episodes of an extremely high heart rate without any known underlying medical conditions.
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