Atrioventricular Nodal Reentry Tachycardia (AVNRT)

Atrioventricular nodal reentry tachycardia (AVNRT) is a type of supraventricular tachycardia, which is a condition characterized by an abnormal heart rhythm originating above the ventricles. AVNRT occurs when there is a reentrant circuit in the atrioventricular node, which is the electrical conduction system that connects the atria to the ventricles.

Causes and Risk Factors

The exact cause of AVNRT is not fully understood, but it is thought to be related to abnormalities in the electrical conduction system of the heart. Risk factors for developing AVNRT include:

• Age: AVNRT can occur at any age, but it is most common in middle-aged and older adults.
• Sex: Women are more likely to develop AVNRT than men.
• Underlying heart disease: Conditions such as coronary artery disease, cardiomyopathy, and valvular heart disease may increase the risk of developing AVNRT.

Symptoms

The symptoms of AVNRT can vary from person to person, but common symptoms include:

• Palpitations: A feeling of rapid or irregular heartbeat.
• Shortness of breath: Difficulty breathing or feeling winded even when at rest.
• Chest pain or discomfort: Pain or pressure in the chest, arm, or jaw.
• Lightheadedness or dizziness: Feeling faint or dizzy.
• Fatigue: Feeling weak or tired.

Diagnosis

AVNRT is typically diagnosed using a combination of the following tests:

• Electrocardiogram (ECG): A test that measures the electrical activity of the heart.
• Holter monitor: A portable device that records the heart's electrical activity over a period of time, usually 24 hours.
• Event monitor: A device that records the heart's electrical activity when symptoms occur.
• Echocardiogram: A test that uses sound waves to create images of the heart and its blood vessels.

Treatment

Treatment for AVNRT depends on the severity of symptoms and the underlying cause. Common treatments include:

• Vagal maneuvers: Techniques such as deep breathing, coughing, or applying pressure to the carotid artery in the neck to help slow down the heart rate.
• Medications: Such as beta blockers, calcium channel blockers, and anti-arrhythmic medications to help control the heart rhythm.
• Catheter ablation: A minimally invasive procedure that uses radiofrequency energy to destroy the abnormal electrical pathway in the atrioventricular node.

Prognosis

The prognosis for AVNRT is generally good, with most people experiencing significant improvement or complete resolution of symptoms with treatment. However, some people may experience recurrent episodes, and in rare cases, AVNRT can lead to more serious complications such as heart failure or stroke.