These electrical signals move across the atria, causing the heart muscles to squeeze and pump blood into the ventricles.
Next, the signals arrive at the AV node. The AV node slows down the electrical signals. This slight delay allows the lower heart chambers to fill with blood. When the electrical signals finally get to the muscles of the ventricles, the lower heart chambers squeeze contract , which pumps blood to the lungs or to the rest of the body.
In a healthy heart, this heart signaling process usually goes smoothly, resulting in a normal resting heart rate of 60 to beats a minute. SVT occurs when faulty electrical connections in the heart set off a series of early beats in the atria.
When this happens, the heart rate becomes so fast so quickly, the heart doesn't have enough time to fill with blood before the chambers contract. As a result, you may feel light-headed or dizzy because your brain isn't getting enough blood and oxygen. Supraventricular tachycardia is the most common type of arrhythmia in infants and children.
It also tends to occur more often in women, particularly pregnant women, though it may occur in anyone. Over time, untreated and frequent episodes of supraventricular tachycardia may weaken the heart and lead to heart failure, particularly if there are other coexisting medical conditions.
In extreme cases, an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest. To prevent an episode of supraventricular tachycardia, it's important to know what triggers the episodes to occur and try to avoid them. Healthy lifestyle changes can help protect your heart. You might want to try:. For most people with supraventricular tachycardia, moderate amounts of caffeine do not trigger an episode of SVT. Large amounts of caffeine should be avoided, however.
Consider keeping a diary to help identify your triggers. Track your heart rate, symptoms and activity at the time of an SVT episode. Supraventricular tachycardia care at Mayo Clinic. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version.
Ablation is considered safe. But it has some rare, serious risks. An electric shock to the heart is called electrical cardioversion. It may be needed if you are having severe symptoms of SVT and your heart rate doesn't go back to normal using vagal maneuvers or fast-acting medicines.
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We are working closely with our technical teams to resolve the issue as quickly as possible. Thank you for your patience. View the changes to our visitor policy » View information for Guest Services ». New to MyHealth? Manage Your Care From Anywhere. Activate Account. It can then slow down abruptly. A normal resting heart rate is 60 to beats per minute bpm. But with SVT your heart rate suddenly goes above bpm. This can happen when you're resting or doing exercise.
It's important to get it checked out. The short circuit is caused by one of three conditions and will have a different location and behavior depending on the cause.
It occurs when a small extra pathway exists in or near the AV node — the "gate" that sends electricity from the upper chambers atria to the lower chambers ventricles. An electrical impulse that enters this pathway will circle rapidly, causing a sudden paroxysmal , fast heartbeat in both the atria and the ventricles. AVNRT is not a life-threatening arrhythmia, but it can cause symptoms such as lightheadedness or syncope fainting. Wolff-Parkinson-White syndrome occurs when an extra muscle fiber connects the upper and lower chambers of the heart.
In normal hearts, the only connection between the upper and lower chambers is the AV node — the electrical signal passes from the atria, through the AV node, and ends in the ventricles. The presence of this extra path can encourage a "short circuit" arrhythmia known as an atrioventricular reciprocating tachycardia AVRT.
The symptoms of AVRT vary widely from mild heart racing to syncope. Due to an increased risk of sudden cardiac death, people with Wolfe-Parkinson White syndrome are advised to have curative catheter ablation. Wolff-Parkinson-White syndrome is congenital , developing in utero. Although present from birth, the tachycardias rapid heartbeats that result from the abnormal electrical connection often take years or decades before they become a problem.
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