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Clinical Electrophysiology: Supraventricular Tachycardia
A tachycardia is a type of heart rhythm disorder in which the heart beats faster than normal (>100 beats per minute). "Supra" means "above," so a supraventricular tachycardia is an abnormally fast heartbeat that originates in the atria, which are the upper chambers of the heart.
Symptoms of Supraventricular Tachycardia
The rapid heart rate of supraventricular tachycardia usually starts and ends abruptly. It can last anywhere from a few minutes to several hours. It is usually felt as an uncomfortable palpitation of the heart, but can also include other symptoms, such as:
- Chest pain
- Shortness of breath
Usually, the heart is otherwise normal.
Causes and Risk Factors of Supraventricular Tachycardia
Supraventricular tachycardia may be caused by an abnormality, such as having:
- Abnormally rapid impulses generated in the atria. This uncommon condition is called paroxysmal atrial tachycardia.
- An abnormal electrical pathway between the upper chambers of the heart and the lower chambers called an accessory pathway or bypass tract.
- Two electrical pathways in the atrioventricular node.
Young people are more likely than older people to experience supraventricular tachycardia.
Treatment for Supraventricular Tachycardia
Several things can be done to stop supraventricular tachycardia by stimulating the vagus nerve, which slows the heart rate. These are usually done by or under a doctor's supervision, but people who frequently have this problem can learn to do it themselves. These include:
- Plunging the face into a bowl of ice-cold water
- Rubbing the neck just below the angle of the jaw to stimulate an area on the carotid artery
- Straining as if having a difficult bowel movement
These are most effective when done soon after the irregular heart beats or arrhythmia starts.
Medical intervention to control arrhythmia is needed if:
- The above are ineffective
- The episode lasts more than 20 minutes
- Symptoms are severe
A doctor can usually stop an episode by giving an injection of a drug. If the arrhythmia does not stop and symptoms are severe, electrical cardioversion may be necessary. This procedure uses an electrical current to reset the heart's rhythm and is performed under effects of sedation.
Although drugs such as beta-blockers, digoxin or others used to prevent arrhythmias may be prescribed to help prevent future episodes, radiofrequency ablation is often performed to destroy the tissues where supraventricular tachycardia starts as this is highly curative.