Rapid heart rate (pulse) :
Rapid heart rate is also called tachycardia. The clinical definition of tachycardia is more than 100 beats per minute rest in adults. Generally the heart rate increases when a person is exercising or under some other circumstances of stress, but when the heart is racing too quickly when a person is resting then it results in tachycardia which may interfere with the heart's ability to pump blood throughout the body.
Symptoms may include dizziness, shortness of breath, palpitations, chest pain, or fainting, although tachycardia, in some people, occurs without causing noticeably related symptoms. The problem with such individuals is that it puts them at risk for serious complications like heart failure, stroke, or sudden cardiac arrest. Such causes of tachycardia include heart disease, hypertension, disturbances in electrolyte balance, and overuse of alcohol or caffeine. Such causes call for proper treatment of the cause and severity by medicine; many times it requires prescribing drugs, changing one's lifestyle, or cardioversion or ablation procedures to restore normal heartbeat.