The normal heart rate for an adult ranges from 60 to 100 beats a minute, although exercise increases that rate. If the heart exceeds 100 beats a minute at rest, it is considered an abnormal tachycardia. The basic cause is a problem with the way the heart stimulates its beat through electrical impulses. The heat's natural rhythm can be disrupted by countless medical conditions.
A physical condition that disturbs the heart's rhythm can be congenital or acquired over the years. For example, a child can be born with a problem such as a defective heart valve that affects the way the heart responds to the electrical signals. Also, the heart can become damaged due to heart disease or heart attack. Conditions called atrial fibrillation or atrial flutter are uncoordinated signals that cause irregularity in the beat, usually rapid, although it is also irregular. A rapid heart rate can also originate in the heart's ventricles due to heart disease or trauma. This ventricular tachycardia causes death without immediate medical intervention.
Other Medical Conditions
Certain medical conditions can affect the heart's rhythm, including high blood pressure, a hyperactive thyroid gland or an electrolyte imbalance. Prescription medications for a range of conditions may cause a faster heart rate, in which case the side effect should be reported to your physician.
Factors that increase the heart rate include heavy use of substances such as caffeine, smoking, alcohol and recreational or prescription drugs. Dramatic emotional states such as anxiety, anger or even excitement can also increase the heart rate.