Supraventricular Tachycardia (SVT)

Overview

Supraventricular tachycardia is an abnormally fast heartbeat. It includes a variety of heart rhythm disorders that start in the ventricles of the atria or AV node.

While a normal heart rate is 60 to 100 beats a minute, if you sustain a heart rate of over 100 beats per minute, it is called tachycardia. When this occurs, you may feel like you have a racing heart because your heart's electrical impulses are not working correctly.

Most people can go about their daily lives with supraventricular tachycardia without any treatment, while others need medications or lifestyle changes to manage the fast heart rate.

Supraventricular tachycardia causes

In some cases, triggers such as psychological stress, lack of sleep, or physical activity can cause a supraventricular tachycardia. In other cases, there is not a noticeable trigger.

Conditions or factors that may lead to a supraventricular tachycardia include:

• Heart disease or heart failure
• Smoking
• Long-term lung disease
• Consuming too much caffeine or alcohol
• Thyroid conditions
• Pregnancy
• Certain medications such as decongestants, herbal diet medications, asthma medications
• Recreational drug use such as cocaine or Crystal meth
• Surgery

Supraventricular tachycardia risk factors

Supraventricular tachycardia is a common type of irregular heartbeat in infants and children.

Risk factors that increase your likelihood of experiencing supraventricular tachycardia include:

• Gender — women are more likely to develop supraventricular tachycardia
• Pregnancy — women who are pregnant are at greater risk of developing supraventricular tachycardia
• Age — while supraventricular tachycardia is the most common type of arrhythmia in children, middle-aged and older people are more likely to experience some types of supraventricular tachycardia
• Coronary artery disease or other heart conditions — if you have another heart condition or have had heart surgery previously, you are at greater risk for supraventricular tachycardia
• Congenital heart disease — people born with a congenital heart defect may experience supraventricular tachycardia episodes
• Anxiety, physical fatigue, or emotional stress
• Drugs and supplements — taking OTC cold medications and prescription medications may increase your risk of developing a supraventricular tachycardia
• Diabetes — people who have uncontrolled diabetes are more likely to develop supraventricular tachycardia
• Recreational drug use — people taking illegal drugs such as crystal meth or cocaine are more likely to experience a supraventricular tachycardia
• Thyroid conditions — people with overactive or underactive thyroid glands are more likely to experience a supraventricular tachycardia

Supraventricular tachycardia symptoms

Symptoms of supraventricular tachycardia differ from person to person. In some people, symptoms may appear suddenly and last anywhere from a couple of minutes to a few days. Others may not experience any symptoms.

Symptoms may include:

• Fluttering in the chest
• Rapid heartbeat
• Shortness of breath
• Dizziness
• Sweating
• Feeling as if your neck is pounding
• Fainting (or almost fainting)

Symptoms in infants or young children may include:

• Sweating
• Poor feeding
• Pale skin
• Pulse rate greater than 200 beats a minute

Supraventricular tachycardia complications

If you have coexisting medical conditions and do not treat supraventricular tachycardia, the condition may weaken your heart and lead to heart failure.

In rare cases, untreated supraventricular tachycardia may cause cardiac arrest.

Supraventricular tachycardia diagnosis

Your doctor can diagnose supraventricular tachycardia by doing a physical exam, taking a full medical history, and performing diagnostic tests.

During the clinic visit, your doctor will determine if anything is triggering your abnormally fast heart rate, how long it lasts, and if it starts and stops suddenly.

If SVT is suspected, your doctor will likely perform an electrocardiogram (EKG, ECG). An EKG will measure your heart’s electrical activity and can record SVT episodes.

If you do not have an episode during the clinic visit or EKG, you will likely wear a portable EKG. This device can record episodes during your normal day to day activities.

Other tests your doctor may order to diagnose an SVT include:

• Blood tests
• Chest X-ray
• Echocardiogram
• Tilt table test
• Stress test
• Electrophysiological testing and mapping

Supraventricular tachycardia treatment

Many patients do not experience symptoms associated with a supraventricular tachycardia episode and do not need to be treated.

For those who experience a sudden supraventricular tachycardia episode, medication is the first-line therapy. Your doctor may also give you instructions on how to slow your heart rate down on your own using vagal maneuvers.

Vagal maneuvers, such as holding your breath, straining, submerging your face in the water, or coughing, can help your heart rate slow down by affecting the vagus nerves. 

If medication and vagal maneuvers are not effective, your doctor may perform a cardioversion or ablation procedure.

• Cardioversion — a procedure where a shock is delivered to your heart; the procedure can restore your normal heart rhythm by affecting the electrical impulses in your heart
• Catheter ablation — a procedure where heat, extreme cold, or radiofrequency energy to ablate an area of heart tissue and to stop the arrhythmia

When to seek care

Generally, supraventricular tachycardia is not life-threatening. If your symptoms are occurring frequently and consistently, and you have other coexisting conditions, you should consult your doctor immediately.

If you suddenly or frequently experience shortness of breath, weakness, dizziness, lightheadedness, and fainting, seek medical attention right away.