The heart normally beats between 60 and 100 beats per minute when a person is at rest, according to MayoClinic.com. Tachycardia, or rapid heartbeat, has many different causes. A rapid heartbeat can originate from different parts of the heart. Some causes of tachycardia occur under normal conditions and have no long-term negative effects on the heart, while other causes indicates heart damage and can have serious consequences.
Sinus Tachycardia Causes
The term sinus tachycardia describes a rapid heartbeat where extra beats are caused by an increase in the firing of the sinus, or SA node, the heart's natural pacemaker.
The SA node controls the rate at which the ventricles, the lower chambers of the heart, contract. Exercise, anxiety, fear, excitement, fever, some forms of thyroid disease and smoking all cause sinus tachycardia.
Heavy caffeine intake and drugs such as cocaine or excess alcohol consumption can also cause sinus tachycardia. The effects of sinus tachycardia last only as long as the stimulus occurs and cause no long-term damage. A person with sinus tachycardia might feel like the heart is pounding.
Ventricular Tachycardia Causes
Ventricular tachycardia originates in the ventricles of the heart. Ventricular tachycardia causes rapid contraction of the ventricles, which doesn't allow them to fill fully with blood. As a result, the body doesn't receive enough oxygen.
Ventricular tachycardia indicates serious damage to the heart, often from a heart attack or damage to the heart muscle, called cardiomyopathy, and must be reversed quickly, within 3 to 5 minutes, to prevent death, the University of Columbia warns. Symptoms include sudden collapse and no pulse.
Supraventricular Causes
Supraventricular tachycardia, often called SVT, originates above the ventricles. Abnormal electrical pathways in the heart, often congenital, according to MayoClinic.com, cause short bursts of tachycardia lasting a few minutes to a few hours in often otherwise healthy young people.
SVTs might cause weakness, lightheadedness, chest pain and shortness of breath. One type of SVT, Wolf-Parkinson-White syndrome, may have no noticeable symptoms, the University of Columbia states.
Atrial Tachycardia Causes
Atrial tachycardia, also called atrial fibrillation, originates in the atria, the upper chambers of the heart. The atria quiver at a rapid rate rather than pumping blood efficiently, resulting in less blood flow through the ventricles and to the rest of the body.
Cardiac factors that lead to atrial tachycardia or atrial fibrillation include heart attack, heart failure, atherosclerosis, recent heart surgery, heart valve disease or infection of the heart. High blood pressure and hyperthyroidism can also cause atrial fibrillation.
Respiratory problems such as emphysema, asthma or blood clots in the lung can lead to atrial tachycardia. Clots can form in the atria and can travel through the heart to other parts of the body, possibly causing stroke, the Merck Manual warns.
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