Tachycardia

Types

Tachycardias are divided into two categories: supraventricular and ventricular.

Supraventricular tachycardias (SVTs)
These rapid heartbeats originate in the heart's upper chambers (the atria) and interfere with the efficient flow of blood into the ventricles. The most common SVTs are:

• Atrial fibrillation
• Atrial flutter
• Atrioventricular (AV) nodal reentrant tachycardia
• Wolff-Parkinson-White syndrome (trioventricular reentrant tachycardia)
• Sinus tachycardia
• Junctional tachycardia

Ventricular tachycardias
These fast heart rhythms begin in the heart's lower chambers (the ventricles). A ventricular tachycardia is usually a medical emergency. Although some ventricular tachycardias can effectively pump blood and maintain blood pressure, serious cases lead to ventricular fibrillation, a quivering of the heart that leads to cardiac arrest (heart attack) and death if not treated immediately.

These abnormalities often occur in people with structural heart problems, such as:

• A scar from a previous heart attack
• Rare inherited heart defects
• Other causes

A comprehensive diagnosis at Mayo Clinic helps to determine the severity of the tachycardia.