A heart rate that is higher than 100 beats per minute is considered to be a high heart rate, also referred to as tachycardia, according to the American Heart Association. However, it should be noted that a high heart rate for one person may be considered normal or less than high for another, depending on age, health status and other personal factors.
There are three different types of tachycardia: supraventricular tachycardia, or SVT, which originates in the upper heart chambers; sinus tachycardia, which results from the heart's natural pacemaker, or the sinoatrial node, sending out signals too frequently; and ventricular tachycardia, which results from the ventricles' electrical systems firing abnormally and affecting the signals from the sinoatrial nodes, as detailed by the American Heart Association.
SVT can be marked by dizziness, lightheadedness, heart palpitations, chest pain and shortness of breath. It can be treated naturally by having the patient cut out certain foods and drinks, such as coffee, alcohol or tobacco, getting rest or receiving a carotid sinus massage.
Sinus tachycardia can be caused by fever, anxiety, fright, emotional distress, strenuous exercise and some drug use. It is marked simply by an increased heart rate. Unlike SVT, doctors will treat sinus tachycardia by treating the underlying causes of the increased heart rate.
Ventricular tachycardia is marked by dizziness, lightheadedness, unconsciousness or cardiac arrest. Treatment for ventricular tachycardia will depend on the underlying causes and can range from medication to surgery.