Supraventricular Tachycardia

The heart has an amazing electrical system that keeps it beating in rhythm. But in some people, the rhythm can get disrupted and go too slow or too fast. Tachycardia is when your heart rate goes over 100 beats per minute. Tachycardia has several causes. To understand how it happens, it helps to know how the heart works.

Causes

Your heart has four chambers, two on the top called atria, and two on the bottom called ventricles. These chambers work together to pump your blood.

The right atrium and ventricle pump blood to your lungs. The left atrium and ventricle pump blood to the rest of your body.

Electrical signals travel through your heart, causing it to pump in a regular rhythm of about 60 to 100 beats per minute. These signals normally start in your right atrium and follow a set pathway.

Abnormal heart rhythms – called arrhythmias -- occur if the signals are fast or too slow. Arrhythmias can also occur if the signals start in unusual spots or follow unusual paths, or if the pathway has damage.
Supraventricular tachycardia, or SVT, is a rapid rhythm that starts in your atria or between your atria and ventricles.

There are two common types of tachycardia. An atrial tachycardia is a spot in your electrical system that fires faster than the regular signal.
The second type is an electrical short circuit called a paroxysmal supraventricular tachycardia, or PSVT. With a PSVT, the electricity goes down one pathway and loops around up another pathway, faster than the normal signal.

SVT can run in families. Some people have heart problems from birth that cause SVT. High blood pressure, heart failure, heart valve problems, sleep apnea, thyroid problems, and heart attacks can cause SVT. Smoking, alcohol, and some drugs can increase your risk of having SVT.

Symptoms

SVT can be a rapid, irregular heart rate that feels like fluttering in your chest. The heart rhythms in PSVT are often regular. Atrial tachycardia can be regular or irregular.

When SVT happens, you may feel certain symptoms such as:

  • Rapid heart rate
  • Dizziness
  • Fainting
  • Shortness of breath, and
  • A tight feeling or pain in your chest

Diagnosis

If you have symptoms, your health care provider will give you a physical exam and ask about your symptoms. He or she will want to know when your symptoms happen, how long you've had them, if you have any other medical problems, and if you're taking medications. If you've been tracking your pulse, be sure to tell your health care provider what you've learned.

You may have tests such as an electrocardiogram, or ECG to map your heart's electrical activity. If the ECG doesn't give enough information, you may need to wear a heart monitor for a day or so.

You may also have other tests, including:

  • A treadmill, or stress test
  • A tilt table test, or
  • An echocardiogram, or heart ultrasound

You may need to get an electrophysiology study, or EPS. In this test, a specialist passes a thin, flexible catheter from your groin or wrist into your heart. At the tip of the catheter is an instrument that precisely maps your heart's electrical activity.

Your health care provider might order other heart tests, X-rays, or urine or blood tests.

Treatment

Treatment depends on the cause of your SVT. You may need medicines to control your heart rate or rhythm, or to help prevent blood clots.
Some cases of SVT can be treated during an EPS, or with surgery.

Some cases of SVT require electrical shocks to stop them. This may require an external device or an implant. Your provider may teach you other, temporary ways to control your SVT at home.

Healthy lifestyle choices can help. If you don't exercise, talk to your provider about the best activity level for you, and get active. If you smoke, quit. Also, make sure you're eating a healthy diet.

Things to Remember

There are several types of supraventricular tachycardia.
The types of testing and treatment depend on the cause of your SVT.
Healthy lifestyle choices can help.

What We Have Learned

Supraventricular tachycardia is a slower-than-normal rhythm that starts in your atria or between your atria and ventricles. True or false? The answer is false. SVT is a faster than normal rhythm.

There are no treatments available for SVT. True or false? The answer is false. There are several treatments for SVT, including medications, procedures, and surgery.