Palpitations and Supraventricular Tachycardia

Palpitations are a common sensation many people describe as their heart racing, fluttering, or pounding. While sometimes harmless, palpitations can also be caused by abnormal heart rhythms such as supraventricular tachycardia (SVT). This guide explains what SVT is, why it happens, and how it can be treated.

What is SVT?

SVT is a type of fast heart rhythm that starts above the heart’s lower chambers (the ventricles). It often comes on suddenly and can stop just as suddenly. Heart rates during SVT are usually very fast—often between 150 and 250 beats per minute.

Why Does SVT Happen?

There are several common causes of SVT:

1. Atrioventricular Nodal Reentrant Tachycardia (AVNRT): The most common type of SVT. It happens when an electrical short-circuit forms inside the heart’s normal wiring system.
2. Atrioventricular Reentrant Tachycardia (AVRT): Caused by an extra pathway that allows electricity to bypass the normal route. A well-known example is Wolff-Parkinson-White (WPW) syndrome.
3. Atrial Tachycardia: Starts from a small area in the upper chambers of the heart that sends out extra signals.

What Do Palpitations Feel Like?

People with SVT often notice sudden episodes of a very fast and regular heartbeat. Some may also feel lightheaded, short of breath, or have chest discomfort. In rare cases, people may faint.

How is SVT Treated in the Moment?

If an episode of SVT occurs, some steps can help stop it:

• Vagal maneuvers: Simple techniques like holding your breath and bearing down, coughing, or putting your face in cold water may reset the heartbeat.
• Medications: A quick-acting medicine called adenosine can be given in the hospital to stop the episode. Other medicines such as beta-blockers or calcium channel blockers may also help.
• Emergency care: If a person is very unwell (for example, with low blood pressure or chest pain), an electric shock (cardioversion) may be needed.

How is SVT Managed Long-Term?

For people who have frequent or bothersome episodes, long-term treatment options include:

• Lifestyle changes: Avoiding caffeine, alcohol, or stress triggers can reduce episodes.
• Daily medicines: Some people may take beta-blockers or calcium channel blockers to reduce the chance of SVT.
• Catheter ablation: A procedure where a heart specialist maps the heart’s electrical system (an electrophysiology study) and uses heat or cold energy to block the short-circuit. This treatment has a very high success rate and is often curative.

Key Takeaway

Palpitations from SVT can be alarming, but in most cases they are treatable and not life-threatening. If episodes are frequent or severe, seeing a heart specialist can provide options for safe and effective treatments, including curative ablation therapy.