<unk>  is a form of cardiac arrhythmia which refers to a rapid beating of the heart. By convention the term refers to heart rates greater than 100 beats per minute in the adult patient.<unk>  may be a perfectly normal physiological response to stress. However, depending on the mechanism of the<unk>  and the health status of the patient,<unk>  may be harmful, and require medical treatment. In extreme cases,<unk>  can be life threatening.<unk>  can be harmful in three ways. Firstly, if the heart is pumping too fast for an extended period of time it will change the balance of oxygen and carbon dioxide in the hemoglobin in the blood; this is normal during exercise but when resting this is quite dangerous. Second, when the heart beats too rapidly, it may pump blood less efficiently. Thirdly, the faster the heart beats, the more oxygen and nutrients the heart requires.  This may leave patients feeling out of breath or cause angina. This can be especially problematic for patients suffering from ischemic heart disease.
Tachycardia
Bradycardia
Normotension
Apnea
QT prolongation
Bradypnea
Palpitation
Hypernea