Supraventricular tachycardia (SVT) is typically not serious unless you have an underlying heart condition. Learn about symptoms and when to call a doctor

Supraventricular tachycardia (SVT) is typically not serious unless you have an underlying heart condition like atrial fibrillation. However, frequent and continuous SVT can lead to heart diseases and in rare cases, SVT can cause serious problems, such as fainting episodes and cardiac arrest.

For most people, having SVT does not affect heart function. However, people with arrhythmias and other conditions can experience life-threatening events with SVT.

What is SVT?

Supraventricular tachycardia is a condition in which your heart beats rapidly and irregularly, over 100 beats per minute (typically 150-220 beats per minute). Supraventricular refers to the upper chamber of the heart above the ventricles, and tachycardia refers to a faster than normal heart rate. 

Under normal conditions, electrical signals originate in the sinoatrial (SA) node, also called the pacemaker of the heart because it regulates heart rate. The SA node is in the atrium, which then spreads to the rest of the heart, coordinating the timing of heart muscle movements. 

In SVT, rapid heartbeat originates in the atria. These abnormal electrical signals cause the atria to contract too early, interrupting the main signal coming from the SA node. As a result, the heart beats rapidly through a separate pathway.

What are different types of SVT?

• Atrioventricular nodal reentrant tachycardia: Most common type of supraventricular tachycardia that causes the electrical signal to circle the atria instead of moving down to the ventricles, triggering rapid heartbeats.
• Atrioventricular reciprocating tachycardia: Occurs when an abnormal pathway connects the atria and ventricles, causing the signal to move in a loop.
• Atrial tachycardia: Caused by abnormal electrical signals originating in the atria that makes the heart beat too rapidly, and usually seen in people with underlying heart diseases.

What causes SVT?

In most cases, the exact cause of SVT. Sometimes, a person may be born with abnormal electrical pathways or electrical circuits in the heart. Scar tissue left behind after heart surgery can also cause faulty circuits to develop. 

Fast heart rate can also be caused by:

• Smoking
• Drinking too much caffeine or alcohol
• Extreme stress
• Certain medications, such as:
  • Asthma drugs
  • Decongestants
  • Herbal diet remedies
• Drug abuse (cocaine or methamphetamine)
• Hyperthyroidism
• Fever
• Sepsis
• Obesity
• Lung diseases

What are the symptoms of SVT?

The primary symptom of SVT is rapid heartbeat lasting for a few minutes to days. Some people may show no symptoms at all. If symptoms do occur, they may include:

• Light-headedness or dizziness
• Chest pain
• Shortness of breath
• Sweating
• Fainting
• Weakness or fatigue
• Palpitations
• Pounding feeling in the neck

When to see a doctor for SVT

Supraventricular tachycardia symptoms are not concerning unless you have heart disease or damage. In rare cases, severe SVT can result in unconsciousness or cardiac arrest. Call 911 if your SVT lasts for more than a few minutes or if you experience the following symptoms along with the condition:

• Chest pain
• Weakness
• Dizziness
• Shortness of breath