Tachycardia is a general term that describes a number of conditions in which the heart beats at an abnormally fast rate at rest (more than 100 beats per minute). It is a type of arrhythmia, which is an abnormal heart rhythm caused by an abnormality in the heart’s electrical system.
There are two main types of tachycardias:
- Supraventricular tachycardias. The word “supraventricular” means “above the ventricles.” Therefore, these tachycardias originate from above the ventricles – either from the upper chambers of the heart (atria) or from the AV node. Generally, supraventricular tachycardias come and go, so they are also known as paroxysmal supraventricular tachycardias. If they occur more regularly, they are called sustained paroxysmal supraventricular tachycardias.
- Ventricular tachycardias. These tachycardias arise from within the ventricles. In general, ventricular tachycardias carry greater risk to the patient than supraventricular tachycardias. Ventricular tachycardias tend to accompany coronary artery disease, but they can also be found in other types of cardiac problems (e.g., cardiomyopathy, mitral valve prolapse, long QT syndrome).
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