This factsheet is for people who have supraventricular tachycardia, or who would like information about it.
Supraventricular tachycardia (SVT) is when the heart beats too fast, usually at a rate of 130 to 250 beats per minute. SVT is a type of arrhythmia (irregular heart rhythm). It is caused by faulty electrical signals in the heart and often affects young healthy people.
Click on the tabs below for more information about supraventricular tachycardia.
Published by Bupa's Health Information Team, June 2010.
About supraventricular tachycardiaTachycardia means a rapid heart rate of more than 100 beats per minute. Supraventricular means that the problem starts in the upper part of the heart (above the ventricles).
SVT attacks are often only temporary and frequently go away on their own without treatment. They often happen in young, healthy people, with attacks becoming less frequent as you get older. Attacks can last from a few seconds, minutes to several hours.
What happens during supraventricular tachycardia?Your heartbeat is controlled by electrical signals (impulses), which start in a part of the heart wall called the sinus node, and travel through the heart making it contract. The signals travel from the atria (the upper chambers of the heart) to the ventricles (the lower chambers) through an area called the atrioventricular (AV) node. The AV node helps to synchronise the pumping action of the atria and ventricles.
SVT occurs when there is an extra electrical pathway in the heart, between the atria and the ventricles. This allows electrical signals to ‘short-circuit’ and re-enter the atria. The signals end up travelling around the heart in a circle. These types of SVT are often referred to as re-entrant tachycardias or paroxysmal SVT. This means symptoms come on suddenly and are temporary.
There are three main types of SVT.
- If the extra pathway is located in your AV node – it is called atrioventricular nodal re-entrant tachycardia (AVNRT).
- If the extra pathway is located between your atria and ventricles – it is called atrioventricular re-entrant tachycardia (AVRT).
- If the extra pathway is located in an area other than the sinus node – it is called atrial tachycardia (a less common type of SVT).
The electrical impulses in a normal heart, a heart with atrioventricular nodal re-entrant tachycardia (AVNRT) and a heart with atrioventricular re-entrant tachycardia (AVRT).