What is supraventricular tachycardia?

Supraventricular tachycardia, or SVT, is a potentially abnormal heart rhythm in which the top chambers of the heart beat rapidly. SVT is a broad term that includes everything from sinus tachycardia, a rapid heartbeat caused by increased physical activity, to an abnormal rhythm like atrial fibrillation, or AFib. 

What are the signs and symptoms of SVT?

SVT symptoms will vary depending on the type of arrhythmia a patient has. For instance, symptoms of AFib can be mild and may come and go over time. Some people with SVT experience no symptoms at all. For those who do experience symptoms, the most common are:

• Heart palpitations 

• Shortness of breath 

• Fatigue 

• Fluttering sensation in the chest

• Pounding heartbeat 

• Feeling that their heart skips a beat 

More severe symptoms of SVT may include: 

• Extremely elevated heartbeat 

• Chest pain 

• Dizziness

• Sweating

• Losing consciousness 

• Blood pressure dropping 

Most of the time, SVT is not life-threatening. However, if you experience symptoms that feel unsafe, seek immediate medical attention by calling 911 or visiting the nearest emergency department. There, medical personnel can evaluate your symptoms and take steps to restore your heart to its natural rhythm.

Risk factors?

While there are some environmental risk factors for SVT, a person can also be born with the condition. The risk factors for SVT are the same as those associated with poor cardiovascular health, including:

• High blood pressure

• High cholesterol

• Advanced age

How is SVT diagnosed? 

“To get a definitive diagnosis, you must catch the arrhythmia in the act,” explains interventional cardiologist Shahbaz Malik, MD, MBBS. “Because EKG tracings are only 10 seconds long, the probability of catching an arrhythmia in that time may be low.”

For this reason, if a patient has symptoms of an abnormal heart rhythm, doctors will often use a portable telemetry monitor to record the patient’s heart rhythm over an extended period. The monitor may be worn for as little as 24 hours or as long as 30 days. If the patient has an episode while wearing the device, it will be recorded. When the testing period is over, a cardiologist will review the results to confirm the diagnosis. 

How is SVT treated?

Treatment for SVT varies, depending on the type of arrhythmia a person has. 

“If a patient is stable, meaning they haven’t experienced chest pain, drops in blood pressure or loss of consciousness, we typically start with medical therapy,” says Dr. Malik. “This usually means using drugs like beta blockers or calcium channel blockers, which help slow down the patient’s heart rate. We may also consider specific classes of medications that can help restore and maintain the heart’s natural rhythm, called antiarrhythmic drugs.” 

If medical therapies don’t work, a cardiologist may recommend more advanced therapies, such as ablation. In certain types of arrhythmias, including atrial flutter and AVNRT, these treatments can cure the arrhythmia.

“With ablation, once we find the abnormal clump of cells causing the abnormal heart rhythm, we can burn or freeze them to cure the arrhythmia,” explains Dr. Malik. 

One type of SVT, AFib, is the most common heart arrhythmia in the U.S. It can cause a clot to develop in the heart, which can lead to a stroke. Treatment often involves taking blood thinners to help reduce their risk of developing blood clots. However, some patients can’t tolerate blood thinners. For these patients, another treatment option is a left atrial appendage closure.

“This is a minimally invasive surgical technique where we place a device in a specific location inside the heart. This device seals off the area in the heart where most clots caused by AFib form,” explains Dr. Malik. “Now, because the clot can’t access the bloodstream, it will never be able to travel to the brain and cause a stroke.”