Supraventricular Tachycardia (SVT)

Supraventricular tachycardia refers to a fast, abnormal heart rhythm that involves both the upper chambers (atria) and lower chambers (ventricles) of the heart. With this condition, the problem originates either in the atria or an area in the middle region of the heart (such as the atrioventricular node).

Generally this condition is not life-threatening but may require treatment as it may cause any of the following signs and symptoms:

  • Heart palpitations
  • Dizziness
  • Lightheadedness
  • Fainting
  • Shortness of breath
  • Chest pain

There are different types of SVT that are classified by the path that the electrical signal takes from the area of the heart where they originate. These include:

  • Sinus tachycardia: The problem is caused when the sinus node sends out signals at a faster than usual rate.
  • Atrioventricular nodal reentry (AVNRT): Normally, the atrioventricular (AV) node receives electrical impulses from the sinus node and filters them to the ventricles. AVNRT occurs when the electrical impulse travels in a circle using extra fibers in and around the atrioventricular (AV) node.
  • Atrioventricular reentry tachycardia (AVRT): This occurs when electrical signals travel through extra fibers between the atria and ventricles. The signals travel down the AV node to the ventricle and back to the atrium, using these extra fibers.
  • Atrial tachycardias: These occur when localized regions in the atria develop the ability to fire rapidly on their own.
  • Wolf-Parkinson-White (WPW) syndrome: Abnormal electrical pathways between the atria and ventricles cause the electrical signal to arrive at the ventricles too soon and to be sent back into the atria. This may result in very fast heart rates, although the condition may not cause symptoms or tachycardia.
  • Bypass tract tachycardias: This refers to types of SVTs where conduction of electrical impulses occur through abnormal, accessory pathways (bypass tracts)--essentially the same as WPW.

Supraventricular Tachycardia Diagnosis

In addition to a complete physical examination and medical history, a variety of tests may be used to diagnose this condition including: ECG (electrocardiogram), Holter ECG monitor, a 24-hour ambulatory Holter monitor, and sometimes, an event monitor or loop monitor.

Treatment for Supraventricular Tachycardia

Medications typically used to treat SVT are:

  • Beta Blockers: A beta blocker is a very safe medication that works by reducing the effect adrenalin has on the heart. Beta blockers are commonly used to treat high blood pressure and other common heart problems.
  • Calcium Channel Blockers
  • Antiarrhythmic agents: These help decrease the frequency and severity of abnormal heart rhythms.
  • Catheter-based ablation: This is a minimally invasive procedure that involves inserting a catheter into the heart to modify or possibly cure cardiac rhythm disturbances. This procedure, which selectively eliminates the heart cells that are causing the SVT, uses radiofrequency (RF) electrical energy – delivered by catheters positioned in the heart – to cauterize the heart cells that are responsible, providing a permanent cure. Learn more about catheter ablation.

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