atrioventricular nodal reentrant tachycardia

3 min read 12-03-2025

Meta Description: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common type of supraventricular tachycardia (SVT). Learn about its causes, symptoms, diagnosis, and treatment options in this comprehensive guide. Understand the mechanisms behind AVNRT, risk factors, and how to manage this heart rhythm disorder effectively. This in-depth article explores both traditional and newer treatment approaches for AVNRT, empowering you with knowledge to navigate this condition.

What is Atrioventricular Nodal Reentrant Tachycardia (AVNRT)?

Atrioventricular nodal reentrant tachycardia (AVNRT) is a type of supraventricular tachycardia (SVT). SVTs originate above the ventricles in the heart's upper chambers (atria). AVNRT specifically involves a re-entrant circuit within the atrioventricular (AV) node. The AV node is a crucial area regulating the heart's electrical signals, controlling the passage of impulses from the atria to the ventricles.

In AVNRT, the electrical impulse follows an abnormal pathway within the AV node, creating a loop. This loop causes a rapid heart rate, typically ranging from 150 to 250 beats per minute. The rapid heart rate can lead to various symptoms, impacting daily life.

Understanding the Mechanism of AVNRT

The AV node possesses two distinct pathways for electrical conduction: a slow pathway and a fast pathway. In AVNRT, the impulse travels down the fast pathway, then backward through the slow pathway. This creates a re-entrant loop, sustaining the rapid heart rhythm. The loop continues until interrupted by medication or other interventions.

Symptoms of AVNRT

The primary symptom of AVNRT is a rapid heartbeat (tachycardia). This can manifest as:

Palpitations: A feeling of a fluttering or racing heart.
Shortness of breath: Due to the increased heart rate and reduced blood flow efficiency.
Dizziness or lightheadedness: Resulting from decreased blood flow to the brain.
Chest pain: Though less common, chest discomfort can occur.
Fainting (syncope): In severe cases, reduced blood flow can lead to fainting.

The symptoms’ severity varies depending on factors like the individual's overall health and the duration of the tachycardia episode.

Diagnosing AVNRT

Diagnosing AVNRT typically involves:

Electrocardiogram (ECG): An ECG provides a real-time recording of the heart's electrical activity, revealing the characteristic pattern of AVNRT. During an episode, the ECG will show a narrow QRS complex tachycardia.
Holter monitor: A portable ECG device worn for 24-48 hours can detect intermittent episodes of AVNRT that might be missed during a routine ECG.
Electrophysiology study (EPS): This invasive procedure maps the heart's electrical pathways to pinpoint the exact location of the re-entrant circuit, aiding in treatment planning.

Risk Factors for AVNRT

While the exact cause of AVNRT remains unclear in many cases, certain factors might increase the risk:

Age: AVNRT is more prevalent in young adults, often presenting between the ages of 20 and 40.
Underlying heart conditions: Certain heart conditions can predispose individuals to AVNRT.
Family history: A family history of AVNRT or other heart rhythm disorders may increase susceptibility.
Certain medications: Some medications might indirectly influence the heart's electrical system, increasing risk.

Treatment Options for AVNRT

Treatment aims to terminate the tachycardia episode and prevent future occurrences. Options include:

Vagal Maneuvers:

These maneuvers stimulate the vagus nerve, slowing the heart rate. Examples include:

Valsalva maneuver: Forced exhalation against a closed glottis.
Carotid sinus massage: Gentle massage of the carotid artery in the neck (performed by a medical professional).

Medication:

Several medications can terminate or prevent AVNRT episodes. These include:

Adenosine: A rapid-acting drug effective in terminating many SVT episodes, including AVNRT.
Beta-blockers: Slow the heart rate and reduce the risk of future episodes.
Calcium channel blockers: Similar to beta-blockers, these medications also help control heart rate.

Catheter Ablation:

This minimally invasive procedure is highly effective for long-term AVNRT cure. A catheter is inserted into a vein and guided to the heart. Radiofrequency energy is then used to destroy the abnormal electrical pathway causing the re-entrant circuit. This is generally considered the most effective long-term solution.

Living with AVNRT

Successfully managing AVNRT involves close collaboration with a cardiologist. Regular check-ups and adherence to the prescribed treatment plan are crucial. Lifestyle modifications, such as regular exercise and a balanced diet, can support overall heart health and might indirectly help manage symptoms. Understanding the triggers for your episodes can also help in preventative strategies. Learning techniques for managing anxiety can also prove beneficial, as stress can sometimes trigger episodes.

When to Seek Immediate Medical Attention

Seek immediate medical care if you experience:

Prolonged episodes of rapid heart rate
Severe dizziness or fainting
Chest pain
Shortness of breath that worsens

AVNRT is a treatable condition. With proper diagnosis and treatment, most individuals can lead full and active lives. Understanding the condition and engaging actively in your healthcare plan is paramount to effective management.

Disclaimer: This information is for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment of any medical condition.