Supraventricular tachycardia

Overview

Supraventricular tachycardia (SVT) is a type of irregular heartbeat, also called an arrhythmia. It's a very fast or erratic heartbeat that affects the heart's upper chambers. SVT also is called paroxysmal supraventricular tachycardia.

The typical heart beats about 60 to 100 times a minute. During SVT, the heart beats about 150 to 220 times a minute. Sometimes it beats faster or slower.

Most people with supraventricular tachycardia don't need treatment. If you do, options may include specific actions or movements that a healthcare professional recommends, and medicines. Some people need treatment to reset the heart rhythm or block faulty signals that cause the irregular heartbeat. Others need a device to control the heartbeat.

Types

Supraventricular tachycardia (SVT) falls into three main groups:

• Atrioventricular nodal reentrant tachycardia (AVNRT). This is the most common type of supraventricular tachycardia.
• Atrioventricular reciprocating tachycardia (AVRT). This is the second most common type of supraventricular tachycardia. Most often, it's seen in younger people.
• Atrial tachycardia. This type of SVT appears to be more common in people who have heart disease. Atrial tachycardia doesn't involve the atrioventricular AV node, which is a small amount of tissue between the upper and lower chambers of the heart.

Other types of supraventricular tachycardia include:

• Sinus nodal reentrant tachycardia (SNRT).
• Inappropriate sinus tachycardia (IST).
• Multifocal atrial tachycardia (MAT).
• Junctional ectopic tachycardia (JET).
• Nonparoxysmal junctional tachycardia (NPJT).

Causes

Supraventricular tachycardia (SVT) is caused by faulty signaling in the heart. Electrical signals in the heart control the heartbeat.

In SVT, a change in these signals causes the heartbeat to start too early in the heart's upper chambers. When this happens, the heartbeat speeds up. The heart can't fill with blood properly. Symptoms such as lightheadedness or dizziness can happen.

How does the heart beat?

To understand the cause of supraventricular tachycardia (SVT), it might help to know how the heart usually works.

The heart has four chambers:

• The two upper chambers are called the atria.
• The two lower chambers are called the ventricles.

Inside the upper right heart chamber is a group of cells called the sinus node. The sinus node makes the signals that start each heartbeat.

The signals move across the upper heart chambers. Then the signals arrive at a group of cells called the AV node, where they usually slow down. The signals then go to the lower heart chambers.

In a healthy heart, this heart signaling process usually goes smoothly. Most often, the heart beats about 60 to 100 times a minute at rest. But in SVT, the heart beats faster than 100 beats a minute. The heart may beat 150 to 220 times a minute.

Complications

Without treatment, frequent bouts of supraventricular tachycardia (SVT) over time may weaken the heart and lead to complications such as heart failure. The risk of this goes up for people who also have other health conditions.

When the heart beats too fast, it may not send enough blood to the body. As a result, the organs and tissues may not get enough oxygen.

A serious bout of SVT may cause fainting or a sudden loss of all heart activity, called sudden cardiac arrest.

Diagnosis

To diagnose supraventricular tachycardia (SVT), a healthcare professional examines you and listens to your heart. A member of your care team takes your blood pressure. Most often, you answer questions about your symptoms, lifestyle habits and health history.

Tests

Tests to diagnose supraventricular tachycardia (SVT) may include:

• Blood tests. A healthcare professional takes a sample of blood to check for other causes of a fast heartbeat, such as thyroid disease.
• Electrocardiogram (ECG or EKG). This quick test checks the heartbeat. Sticky patches, called electrodes, attach to the chest and sometimes to the arms or legs. An ECG shows how fast or how slow the heart is beating. Some personal devices, such as smartwatches, can do ECGs. Ask your healthcare team if this is an option for you.
• Holter monitor. You wear this portable ECG device for 1 to 2 days to record the heart's activity during your daily routine. It can spot irregular heartbeats that aren't found during a regular ECG.
• Event recorder. This device is like a Holter monitor, but it records only at certain times for a few minutes at a time. You typically wear it for about 30 days. You usually push a button when you feel symptoms. Some devices record on their own when an irregular heartbeat occurs.
• Implantable loop recorder. This device records the heartbeat constantly for up to three years. It's also called a cardiac event recorder. It shows how the heart is beating during daily activities.
• Echocardiogram. This test uses sound waves to make images of the beating heart. It can show how blood flows through the heart and heart valves.

Other tests that may be done to diagnose SVT include:

• Exercise stress test. Exercise may trigger SVT or make it worse. During a stress test, you usually exercise on a treadmill or stationary bicycle while your heart activity is checked. If you can't exercise, your healthcare professional may give you medicine that raises your heart rate like exercise does. Some people get an echocardiogram during a stress test.
• Tilt table test. This test can help find out if a fast heartbeat leads to fainting. A healthcare professional checks your heart rate, heart rhythm and blood pressure while you lie flat on a table. Then, your healthcare team carefully tilts the table to a standing position. A member of your care team watches how your heart and nervous system respond to the changes in position.

• Electrophysiological (EP) study. This test helps show where faulty heart signals start in the heart. Doctors mostly use an EP study to diagnose some specific types of tachycardias and irregular heartbeats.

  During this test, a doctor places one or more flexible tubes called catheters through a blood vessel, usually in the groin. The catheters go to various areas in the heart. Sensors on the tips of the catheters record the heart's electrical signals.

Lifestyle and home remedies

If you have supraventricular tachycardia (SVT), a heart-healthy lifestyle is an important part of your treatment plan.

Try these tips to keep the heart healthy:

• Don't smoke. Smoking is a major risk factor for heart disease. If you smoke and can't quit, talk to your care team about programs or treatments that can help.
• Eat healthy foods. Choose fruits, vegetables and whole grains. Limit salt and saturated fats.
• Get regular exercise. Exercise at least 30 minutes a day on most days of the week. Talk to your healthcare team about the amount and type of exercise that's best for you.
• Stay at a healthy weight. Being overweight raises the risk of heart disease. Ask your healthcare team what weight is best for you.
• Manage high blood pressure, high cholesterol and diabetes. Make lifestyle changes and take medicines as directed. Get regular health checkups.
• Manage stress. Find ways to help lower your stress. For instance, you could practice mindfulness and join a support group. If you have anxiety or depression, talk to your care team about treatments that can help.
• Get good sleep. Poor sleep may raise the risk of heart disease and other health conditions. Adults should aim for 7 to 9 hours of sleep daily.
• Limit alcohol. If you choose to drink alcohol, do so in moderation. For healthy adults, that means no more than one drink a day for women and two drinks a day for men.

Preparing for an appointment

If you have a very fast heartbeat, make an appointment for a health checkup. If the fast heartbeat lasts longer than a few minutes, get medical care right away.

You may be referred to a doctor trained in heart conditions, called a cardiologist. You also might see a doctor trained in heart rhythm conditions, called an electrophysiologist.

Appointments can be brief. Because there's often a lot to talk about, it's a good idea to be prepared for your appointment. Here's some information to help you get started.

What you can do

When you make the appointment, ask if there's anything you need to do in advance. For instance, you may need to stay away from food or drinks for a few hours. You may need to do this if your care team orders any tests.

Make a list ahead of time that you can share with your healthcare team. Your list should include:

• Any symptoms, including those that may not seem related to your heart.
• Important personal information, including any major stresses or recent life changes.
• All medicines, vitamins and supplements that you take. Include any that you bought with or without a prescription. Also include the amounts you take.
• Questions to ask your care team.

For supraventricular tachycardia, basic questions to ask your healthcare professional include:

• What is the likely cause of my fast heart rate?
• What kinds of tests do I need?
• What's the best treatment for me?
• What are the risks of SVT?
• How often do I need health checkups?
• How do other conditions I have or the medicines I take affect my heartbeat?
• Do I need to limit or stop doing any activities?
• Is there any printed information that I can take home with me? What websites do you recommend?

Feel free to ask any other questions.

What to expect from your doctor

Your healthcare team is likely to ask you many questions. Be ready to answer them, because that may save time to go over any details that are important to you. Your care team may ask:

• When did the symptoms start?
• How often do you have a fast heartbeat?
• How long does the fast heartbeat last?
• Does anything, such as exercise, stress or caffeine, make the symptoms worse?
• Does anyone in your family have heart disease or a history of irregular heartbeats?
• Has anyone in your family had sudden cardiac arrest or died suddenly?
• Do you smoke or have you ever smoked?
• How much alcohol or caffeine do you use, if any?
• What medicines do you take?
• Do you have high blood pressure, high cholesterol, diabetes or other conditions that may affect your heart health?