Supraventricular tachycardias (SVT) are a group of abnormally fast heart rhythms. Normally, a special group of cells begin the electrical signal to start your heartbeat. These cells are in the sinoatrial (SA) node. This node is in the upper right chamber of your heart (right atrium). The signal quickly travels down your heart’s conducting system to the two lower chambers of your heart (ventricles). Along the way, the signal moves through the atrioventricular (AV) node, a special group of cells between your atria and your ventricles. From there, the signal travels to your left and right ventricle. As it travels, the signal triggers nearby parts of your heart to contract. This helps your heart pump in a coordinated way.
In SVT, the signal to start your heartbeat doesn’t come from the SA node the way it should. Instead, it comes from another part of the left or right atrium, or from the AV node. It is called “supraventricular” because the signal begins someplace above your ventricles. An area outside the SA node begins to fire quickly, causing a rapid heartbeat of over 100 beats per minute. This shortens the time your ventricles have to fill. If your heartbeat is fast enough, your heart may not be able to pump enough blood forward to the rest of your body. The abnormal heart rhythm may last for a few seconds to a few hours before your heart returns to its normal rhythm.
What causes supraventricular tachycardia?
SVT is usually a result of faulty electrical signaling in your heart. It is commonly brought on by premature beats. Some types of SVT run in families, so genes may play a role. Other types may be caused by lung problems. It can also be linked to a number of lifestyle habits or medical problems. Some of these include:
- Excess caffeine or alcohol
- Heavy smoking
- Certain medicines
- Heart attack
- Mitral valve disease
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