Tachyarrhythmia (Fast Heart Rate)

Some fast heart rates are appropriate. For instance, if you are being chased, your body has a need for more oxygen; therefore, it is necessary for your heart rate to rise to meet this demand. This is called sinus tachycardia—a normal response and a normal rhythm. Other high heart rates occur because there is a problem with the heart or its conduction system (the part of the heart that generates electricity and allows the electricity to travel down the heart muscle, causing it to beat).

There are two types of fast heart rates, or tachyarrhythmias:

• Tachycardia - a rate higher than 100 beats per minute
• Fibrillation - a rate higher than 350 beats per minute

Fast heart rates are also classified based on where in the heart they begin:

• The upper chambers - the atria
• The lower chambers - the ventricles

Fast heart rates that occur in the upper chambers of the heart are called supraventricular tachycardias (SVTs) and include:

• Atrial flutter
• Atrial fibrillation (AF)
• AV nodal reentrant tachycardia (AVNRT)
• Wolf-Parkinson-White (WPW)

Those occurring in the lower chambers of the heart are:

• Ventricular tachycardia (VT)
• Ventricular fibrillation (VF)

Atrial fibrillation is the most common serious arrhythmia worldwide, with an estimated 2.5 million affected persons in North America and 4.5 million in Europe.¹ Not all people with arrythmias require treatment. Supraventricular tachycardias, such as atrial fibrillation, and ventricular tachycardia are usually not medical emergencies, but require prompt medical attention. Ventricular fibrillation is fatal if not treated immediately.

Normal Rhythm

Every normal heart has a normal rhythm. That rhythm varies from person to person. In most healthy people, the heart at rest beats about 60 to 100 times per minute. A small bunch of heart cells called the sinoatrial node keeps time.

¹ Fuster V, Ruden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation—executive summary: a report of the American College of Cardiology/American Heart Association task force on practice guidelines and the European Society of Cardiology Committee for practice guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation). Circulation. 2006;114(7):700-752.