AV nodal reentrant tachycardia

AV-nodal Reentrant Tachycardia (AVNRT)

An ECG showing the characteristic pattern of AVNRT.

AV-nodal Reentrant Tachycardia (AVNRT) is an abnormal, rapid heart rhythm originating from the heart's upper chambers. Classified as a subtype of supraventricular tachycardia (SVT), AVNRT arises from an area within the heart above the Bundle of His. It holds the distinction of being the most prevalent regular SVT, and it manifests more frequently in females, accounting for approximately 75% of the reported cases.

Overview

AVNRT is characterized by an aberrant circuit within the heart's atrioventricular (AV) node. This leads to rapid and repetitive firing of electrical impulses, resulting in a fast heart rate.

Epidemiology

• Gender Prevalence: AVNRT is notably more common in women than men, with females constituting around three-quarters of all cases.
• Age Distribution: While AVNRT can occur at any age, it is most frequently diagnosed in young and middle-aged adults.

Symptoms

The primary symptom associated with AVNRT is:

• Palpitations: A sensation where individuals feel their heartbeats are rapid, pounding, or fluttering.

Other potential symptoms include:

• Dizziness
• Shortness of breath
• Chest discomfort
• Fatigue

Causes and Mechanisms

AVNRT is precipitated by the presence of two pathways within the AV node – a fast pathway and a slow pathway. An electrical impulse can circulate between these pathways, leading to the rapid heart rhythm characteristic of AVNRT.

Diagnosis

A definitive diagnosis of AVNRT is typically made using an ECG, which captures the electrical activity of the heart. Additional diagnostic tests might include:

• Holter monitoring
• Stress testing
• Electrophysiological study

Treatment

Treatment strategies for AVNRT aim to regulate the heart rhythm and alleviate symptoms:

• Physical Maneuvers: Certain maneuvers, like the Valsalva maneuver, can help in terminating the abnormal rhythm.
• Medications: Drugs such as beta-blockers or calcium channel blockers can be prescribed to control the heart rate.
• Synchronized Cardioversion: In rare cases, an electric shock is delivered to reset the heart's rhythm.
• Radiofrequency Ablation: For individuals experiencing recurrent episodes, this procedure can be employed to destroy the aberrant conducting tissue in the heart responsible for AVNRT.

A depiction of the radiofrequency ablation procedure.

Prognosis

With appropriate treatment, most individuals with AVNRT can lead normal, symptom-free lives. However, it's crucial to consult with a cardiologist for an accurate diagnosis and personalized treatment plan.

See Also

• Arrhythmias
• Supraventricular Tachycardia
• Electrophysiology Study

References

AV nodal reentrant tachycardia Resources
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