Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia (SVT), characterized by a rapid and irregular heartbeat due to faulty electrical signaling in the heart. AVNRT episodes often start and end suddenly, with the heart beating between 120 and 280 times per minute.
Symptoms
The most common symptom of AVNRT is a sudden onset of a fast heartbeat. Symptoms may vary in intensity and include:
- Pounding or fluttering heartbeat (palpitations).
- Pounding sensation in the neck.
- Chest tightness, pressure, or pain.
- Dizziness or lightheadedness.
- Shortness of breath.
- Sweating.
- Weakness or extreme tiredness.
- Fainting or near fainting.
In Children
Symptoms may include:
- Sweating for no apparent reason.
- Difficulty feeding.
- Changes in skin color.
- A noticeably fast heartbeat.
When to Seek Medical Care
- Call 911 or your local emergency number if a fast heartbeat lasts for several minutes and is accompanied by:
- Chest pain.
- Dizziness or fainting.
- Trouble breathing.
- Make an appointment if you notice unexplained changes in your heartbeat or if a child shows any symptoms of AVNRT.
Causes
AVNRT occurs due to faulty electrical signaling in the heart caused by an extra signaling pathway, also known as a reentrant circuit. This pathway disrupts the normal rhythm and causes the heart to beat too early and too fast, preventing proper blood pumping.
The exact cause of the extra pathway is unclear, but structural changes in the heart may contribute.
Risk Factors
While AVNRT can occur in anyone, certain factors increase its likelihood:
Health Conditions:
- Coronary artery disease.
- Heart valve disease.
- Congenital heart defects.
- Heart failure.
- Obstructive sleep apnea.
- Thyroid disorders.
- Lung diseases such as COPD.
- Poorly controlled diabetes.
Lifestyle Factors:
- Emotional stress.
- High caffeine intake.
- Excessive alcohol use (15+ drinks/week for men; 8+ drinks/week for women).
- Smoking or nicotine use.
- Use of stimulant drugs (e.g., cocaine, methamphetamine).
Complications
Though AVNRT is usually not life-threatening, potential complications include:
- Worsening of pre-existing heart disease.
- Sudden cardiac arrest (rare but possible in severe cases).
Diagnosis
AVNRT is diagnosed using tests that monitor the heart’s electrical activity and rhythm:
- Electrocardiogram (ECG): Records the heart’s electrical signals.
- Holter monitor: Tracks the heart’s rhythm over 24-48 hours.
- Event monitor: Worn for longer periods to detect irregular rhythms during episodes.
- Electrophysiology study: Identifies the location of the faulty electrical pathway.
Treatment Options
AVNRT may not always require treatment. When treatment is needed, it focuses on restoring and maintaining a normal heart rhythm:
Immediate Interventions:
- Vagal maneuvers: Specific physical actions, such as bearing down or applying ice to the face, to slow the heart rate.
- Medications: Drugs like adenosine may be used to stop a rapid heart rate during an episode.
Long-Term Treatments:
- Medications:
- Beta blockers.
- Calcium channel blockers.
- Anti-arrhythmic drugs.
- Cardioversion:
- An electric shock delivered to reset the heart rhythm.
- Catheter Ablation:
- A minimally invasive procedure that destroys the extra electrical pathway causing the irregular heartbeat.
Lifestyle Changes for Management and Prevention
Adopting heart-healthy habits can reduce the risk of AVNRT episodes:
- Limit caffeine and alcohol intake.
- Quit smoking and avoid nicotine.
- Manage stress through relaxation techniques like meditation or yoga.
- Exercise regularly and maintain a healthy weight.
- Control chronic conditions such as high blood pressure, diabetes, and thyroid disorders.
Prognosis
With proper treatment, most people with AVNRT can lead normal, active lives. Early diagnosis and management help prevent complications and improve quality of life.
