What Is Supraventricular Tachycardia?
Supraventricular tachycardia, otherwise known as SVT, is an abnormally fast heart rhythm caused by improper electrical activity in the upper chambers of the heart. This means that your heart beats fast for a reason other than exercise or stimulation. SVT heart rhythms can range anywhere from 100bpm to 300bpm and last for several seconds to hours. Many cases of SVT are not life-threatening, but if they happen frequently or for prolonged periods, they can be indicative of a serious heart condition.
Causes of SVT include, but are not limited to the following:
- Excessive caffeine intake
- Certain medications
- Smoking cigarettes
- Previous heart surgery
- Wolff–Parkinson–White Syndrome
- Heart disease
- Certain illegal drugs
- Thyroid disorders
There are three main types of supraventricular tachycardia:
This is the most common type of supraventricular tachycardia. Atrial fibrillation refers to rapid and irregular beating of the atria. It is often described as a “quivering” of the heart and, if left untreated, can lead to serious issues such as stroke.
Paroxysmal Supraventricular Tachycardia
Also known as PSVT, paroxysmal supraventricular tachycardia refers to a rapid, racing heartbeat that starts and stops abruptly. Episodes of PSVT range from 130bpm to 300bpm and last for only a few seconds. PSVT is generally not dangerous but can produce life-altering symptoms such as dizziness and fatigue.
Atrial flutter is the rarest type of SVT. It refers to a rapid heartbeat that originates in the atrial chambers of the heart. It is similar to atrial fibrillation in that, if left untreated, it can lead to serious issues such as stroke.
- Rapid heartbeat of over 100bpm
- Heart palpitations
- Shortness of breath
- Chest pain
- Rapid breathing
If your primary doctor suspects that you have SVT, they will refer you to a special type of cardiologist called an electrophysiologist. Electrophysiologists are cardiologists who specialize in heart rhythm disorders. To confirm SVT, your electrophysiologist will perform an electrocardiogram or EKG in office. An electrocardiogram records the current rhythm of the heart beat. If you only experience occasional episodes of SVT, it is unlikely that an EKG will catch this. In this case, your doctor will have you wear either a holter monitor or a cardiac event monitor. A holter monitor is a small, portable machine that uses electrodes to record your heart’s activity for 24 to 48 hours. If your SVT is not caught in this timeframe, you may have to wear a cardiac event monitor. A cardiac event monitor is similar to a holter monitor, but it is worn for an extended period of time – usually 30 days. These tests are the only way to catch an episode of supraventricular tachycardia for your doctor to diagnose you. To rule out any other cardiac issues, your doctor may order an echocardiogram, which is basically an ultrasound of the heart. This will make sure that there are no structural problems with your heart.
Treating supraventricular tachycardia depends on the type and cause of the SVT. Some cases of SVT can be managed with diet and lifestyle changes, such as exercising and eliminating caffeine. A non-invasive treatment for SVT is medication, such as beta blockers or calcium channel blockers. In serious and prolonged cases of SVT, a cardiac ablation may be needed. During a cardiac ablation procedure, a catheter is inserted near the patient’s groin and guided upwards into the heart. Using guided fluoroscopy, your electrophysiologist then tries to trigger an episode of SVT to see where the inappropriate rhythm is originating from. If the source can be identified, that portion of heart tissue is then “burned” or scarred, making it impossible to send an improper signal any longer.