Supraventricular tachycardia (SVT) is an abnormal rapid heart rate that starts in the upper chambers, or the aria, of the heart.
SVT is also called paroxysmal supraventricular tachycardia (PSVT) or paroxysmal atrial tachycardia (PAT).
Normal vs. Abnormal Heart Rate Increases
Not all increases in heart rate are abnormal. Sometimes it is normal to have an increased heart rate, such as during exercise, with a high fever or when under stress. This fast heart rate, called sinus tachycardia, is a normal response to these stressors and is not considered a medical problem.
Types of SVT that are abnormal include:
- Atrial fibrillation (most common)
- Atrioventricular nodal reentrant tachycardia (AVNRT)
- Atrioventricular reciprocating tachycardia (AVRT), including Wolff-Parkinson-White syndrome
Causes and Risk Factors for SVT
In SVT, abnormal firing of the heart's electrical system causes the heart to beat too fast.
Some medicines can cause SVT:
- Digoxin: Overly high levels of the heart medicine digoxin (such as Lanoxicaps or Lanoxin) can cause some types of SVT (such as Wolff-Parkinson-White syndrome) to get worse. But digoxin may be used to treat some other types of SVT (such as atrial fibrillation).
- Theophylline, a type of bronchodilator
In rare cases, conditions that affect the lungs such as chronic obstructive pulmonary disease (COPD) or pneumonia can also cause a type of SVT called multifocal atrial tachycardia (MAT).
The following increase your risk for SVT:
- Alcohol use
- Caffeine use
- Illicit drug use
Symptoms of SVT
Symptoms may start and stop suddenly, and can last for a few minutes or several hours. Supraventricular tachycardia lasting more than half of the day is considered an incessant SVT.
- Palpitations, an uncomfortable feeling that your heart is racing or pounding
- Rapid pulse, especially at your neck, where large arteries are close to the skin
- Feeling anxious
- Feeling dizzy or lightheaded
- Near-fainting or fainting
- Shortness of breath
- Chest pain or tightness
- Throat tightness
Diagnosing Supraventricular Tachycardia
Supraventricular Tachycardia is diagnosed during an Electrophysiology Study. During the study, an electrophysiologist will perform a minimally invasive procedure to determine where and when the signals from your heart begin.
Treating SVT at St. Joseph's Heart & Vascular Institute
If you do not have symptoms, SVT may not require treatment.
If symptoms occur or if you have another heart disorders, treatment may be necessary.
If SVT recurs, you may need long-term treatment, including:
- Daily medications such as beta-blockers or other anti-arrhythmic medicines to prevent an episode or to slow the heart rate
- Catheter ablation; currently the treatment of choice for most SVT's
- Pacemakers to override the fast heartbeat; very occasionally used in children with SVT who have not responded to any other treatment
- Surgery to change the pathways in the heart that send electrical signals; this may be recommended in some cases for people who need other heart surgery.
Emergency treatment of SVT may include:
- Electrical cardioversion, the use of electric shock to restore a rapid heartbeat back to normal
- Medicines through a vein, including adenosine and verapamil. Other medications may be used, such as procainamide, beta-blockers and propafenone