Supraventricular tachycardia (SVT) is a very rapid heartbeat (usually between 151 and 250 beats per minute, or BPM) and can cause a number of serious health issues. It’s seen in just over 2 out of every 1,000 people, affecting children and adults alike.
There are several types of SVT, with each involving a different part of the heart or having a unique origin. Signs of SVT include a racing heart rate and other symptoms that can cause discomfort, pain, or feeling faint.
A cardiac monitor is used to record the heart to identify an abnormal rhythm. Treatment for SVT ranges from tips you can apply at home to procedures that can get rid of or bypass the source of this condition.
Supraventricular tachycardia is actually a group of arrhythmias — or abnormal heart rhythms — characterized by an unusually fast heartbeat.
The phrase “supraventricular” means that the issue happens above the heart’s two lower chambers (ventricles). The two upper chambers are the atria. Tachycardia refers to any type of rapid heartbeat.
Normally, the electrical signal that starts every heartbeat originates in the sinoatrial (SA) node in the upper right atrium. Then, it travels through the heart’s circuitry to the atrioventricular (AV) node in the lower right atrium and down into the ventricles to help them pump blood out of the heart.
Along the way, the electrical impulse travels through the rest of the heart muscle, causing it to contract. This usually happens in a very coordinated and synchronized manner.
When your heart is in SVT, the electrical signal comes from somewhere else instead of the SA node — sometimes even from the AV node where it’s supposed to travel through. Because the heart beats much faster than normal, the ventricles can’t always fill with enough blood to supply all the organs and tissue in your body.
SVT can develop in several ways. Some of the more common types of SVT include:
- Atrial fibrillation (AFib). The most common form of heart arrhythmia, AFib affects
2.7 million adultsin the United States alone. This happens when the atria beat more quickly than the ventricles in an irregular rhythm.
- Atrial flutter. Atrial flutter happens when your atria beat faster than the ventricles, sometimes beating up to 300 bpm and resulting in a pulse rate of around 150 bpm.
- Paroxysmal SVT (PSVT). SVT episodes occur occasionally. They are limited, and they come and go.
- Atrioventricular node reentrant tachycardia (AVNRT). The most common type of SVT. AVNRT results from an additional pathway (reentrant circuit) near the AV node that causes the heart to beat too early.
- Atrioventricular reciprocating tachycardia (AVRT). This second most common type of SVT occurs when a second connection between the upper and lower chambers develops. This allows the electrical impulses to move in a faster circuit than they would without that additional connection.
- Atrial tachycardia. This causes the atria to beat at an accelerated rate. The electrical signal originates from a location other than the SA node.
- Multifocal atrial tachycardia. More common in older adults with respiratory problems, this type is characterized by electrical signals coming from different areas, causing the atria to contract.
SVT is caused by the improper functioning of the heart’s electrical system. Sometimes, an SVT episode develops after strenuous exercise, a period of stress, or after stimulant use.
In some cases, people are born with an extra electrical pathway in their heart that leads to abnormal electrical activity. For some, it can be due to abnormal electrolytes or thyroid function. Sometimes there is no obvious trigger. But many people with SVT have other health problems that affect heart function, including:
- heart disease
- heart failure
- chronic obstructive pulmonary disease (COPD)
- too much caffeine, alcohol consumption, or toxin use
- drug use (especially stimulants and methamphetamine)
- thyroid disease
- various medications, including antihistamines, decongestants, and other cold or asthma medications
The most common symptom of SVT is the feeling that your heart is racing. It may feel like it’s pounding out of your chest.
Other symptoms may include:
- exercise intolerance
Seek immediate medical attention
Go to an emergency room if your SVT episode occurs with:
- chest pain
- difficulty breathing
SVT episodes can develop suddenly and end just as quickly and unpredictably. That’s why it can be difficult to record the abnormal heart rate and any changes in heart rhythm caused by the condition.
This is because SVTs have specific heartbeat patterns that can be seen on an ECG readout. For example, atrial fibrillation has its own unique patterns. ECG information helps doctors make accurate diagnoses.
If your heart is not in SVT while undergoing an ECG, your doctor may recommend a wearable heart monitor, such as a Holter monitor or event monitor. You may also be asked for a blood test to check for electrolyte levels and any signs of infection.
Mild cases of SVT may not need any treatment, but they first need to be diagnosed.
You may want to consider a treatment plan if SVT episodes occur frequently, or they disrupt your life in any way. Treatments range from steps you can take at home to heart procedures, usually performed with a catheter (rather than open surgery).
If you feel your heart starting to race with an SVT episode, vagal maneuvers that stimulate the vagus nerve can help control your heart rate and other important functions.
Here are some vagal maneuvers you may want to try:
- Pinch your nose and close your mouth while you try to exhale for 20 seconds. The pressure in your head will lead to changes in blood pressure. This can trigger a return to a normal heart rate.
- Cough a few times.
- Hold your breath and bear down as if you’re having a bowel movement.
- Dunk your face in a bowl of ice-cold water.
Ask a doctor before you perform any of these remedies to make sure they’re safe for you to try.
A doctor may also advise you to make some of the following lifestyle changes to better manage your condition:
- Have little or no caffeine.
- Drink little or no alcohol.
- Try to quit smoking if you smoke.
- Exercise regularly, though working out with a partner is safer in case of a major SVT episode.
- Try to get at least 7 to 8 hours of sleep at night, and treat obstructive sleep apnea if applicable.
Medications can help slow down a racing heart if your SVT episodes are frequent and last long, or if they’re causing symptoms such as:
- chest pain
- shortness of breath
- reduced blood pressure
For people with recurrent SVT, including children, ablation is considered generally safe and effective. According to a 2015 study, this is true even if you’re taking SVT medications, or you choose not to take medications in the long term.
Ablation involves the use of radio waves or cold temperatures to destroy the cells causing the abnormal heart rate. It’s also been shown to be safe and effective in treating people born with
SVT is different from a condition called ventricular tachycardia (VT).
The main difference is that SVT begins above the ventricles, and VT starts in the heart’s lower chambers.
The other key difference is that VT can have more severe and life threatening symptoms because it originates in the heart’s primary pumping chambers.
Sinus tachycardia originates in the SA node and usually presents milder symptoms than SVT and is not considered an arrhythmia.
A heart rate with sinus tachycardia is usually between 100 and 150 BPM. SVT is typically characterized by a rate of between 151 and 250 BPM.
See a doctor if you feel your heart racing faster or longer than it should after strenuous activity, or speeding up for no apparent reason.
While supraventricular tachycardia is rarely life threatening, it’s important to know what is going on with your heart so you can pursue treatment if needed.