Tachycardia is a heart rate of more than 100 beats per minute. The heart normally beats at a rate of 60 to 100 times per minute, and the pulse (felt at the wrist, neck or elsewhere) matches the contractions of the heart's ventricles, the heart's two powerful lower chambers.

Tachycardia can be part of the body's normal response to fever, rapid blood loss or strenuous exercise. It also can be caused by medical problems, such as an abnormally high level of thyroid hormones, called hyperthyroidism, or by an adrenal gland tumor called pheochromocytoma. In some people, tachycardia is the result of a cardiac arrhythmia (a heart-generated abnormality of heart rate or rhythm), coronary artery disease or an abnormality of a heart valve. Tachycardia can also be caused by lung problems, such as pneumonia or a blood clot in one of the lung's arteries. In other cases, tachycardia can be a side effect of some foods and drinks, including coffee, tea, alcohol and chocolate; tobacco; or medication, including epinephrine (used in various medications), ephedrine (used in various medications), aminophylline (Phyllocontin, Truphylline), atropine (used in various medications), digoxin (Lanoxin) and others.

Symptoms of tachycardia can include:

• Dizziness, lightheadedness and fainting
• Fatigue (an abnormally tired feeling)
• Palpitations (awareness of a rapid heartbeat)
• Breathlessness

If tachycardia is caused by a medical illness, there will be additional symptoms that are specific to that illness. For example, people who have tachycardia caused by hyperthyroidism also can experience nervousness, insomnia, sweating, tremors and other symptoms related to high levels of thyroid hormones. Tachycardia caused by heart or lung disease often is accompanied by chest pain or shortness of breath or lightheadedness.

Your doctor will ask about your family history of heart disease and cardiac arrhythmias. He or she also will review your personal medical history, and will ask whether you have any of the conditions that can lead to tachycardia, including coronary artery disease, heart valve abnormalities, heart valve disease resulting from rheumatic fever, lung disease, thyroid disorders, medications and dietary factors. You also will be asked to describe your symptoms.

During the physical examination, your doctor will check your heart rate and rhythm, together with your pulses. In tachycardia, your pulse may not match the heart sounds your doctor hears through a stethoscope. Your doctor also will check for an enlarged heart, for heart murmurs (one sign of a heart valve problem), for abnormal lung sounds and for physical signs of thyroid abnormalities (enlarged thyroid gland, tremors, muscle wasting and an abnormal protrusion of the eyes).

To further evaluate your tachycardia, your doctor will order an electrocardiogram (EKG). However, because some forms of tachycardia come and go, a one-time office EKG may be normal. If this is the case, you may need a test called ambulatory electrocardiography. For this test, you will wear a portable EKG machine called a Holter monitor for a period, usually for 24 hours. If symptoms occur infrequently, you may have to wear a monitor for much longer. You will be taught to press a button to record EKG readings when symptoms occur.

Depending on the results of your physical examination, other tests may be necessary, including blood tests to measure levels of thyroid hormones, an echocardiogram to check for heart valve abnormalities, a coronary angiogram to check for coronary artery disease, and other tests. Sometimes, physicians do "electrophysiology testing," in which they insert special catheters within the heart to collect information on the patterns of the heart's electrical activities.

How long tachycardia lasts depends on its cause. For example, tachycardia resulting from fever will go away when body temperature returns to normal. Tachycardia resulting from blood loss will end when the patient is stabilized with intravenous (IV) fluids and/or blood transfusions. Tachycardia resulting from hyperthyroidism or an adrenal gland tumor will go away when the disorder is treated. Tachycardia caused by medications or diet will go away quickly, usually within hours, when the chemical that is causing the problem is used up by the body or excreted in the urine. Tachycardia caused by cardiac problems can last a long time.

Tachycardia caused by coronary artery disease can be prevented by taking these actions to modify cardiac risk factors:

• Eat a low-fat diet.
• Control high blood pressure and cholesterol levels.
• Don't smoke.
• Control your weight.
• Exercise regularly.

Tachycardia that occurs as a side effect of medication can be prevented by reducing the dose or changing medications. In general, people who are prone to tachycardia should avoid or limit their consumption of caffeinated beverages, chocolate and alcohol.

Not all episodes of tachycardia can be prevented.

The treatment of tachycardia depends on its cause:

• Fever — Fever-related tachycardia can be treated with fever-reducing medications, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin and others). If the fever is caused by a bacterial infection, antibiotics also may be needed.



• Blood loss — To treat blood loss, the patient first is stabilized with fluids given intravenously (into a vein) or blood transfusions. Then, the source of the bleeding is found and stitched, or corrected with surgery.



• Hyperthyroidism — Hyperthyroidism can be treated with antithyroid medications such as propylthiouracil (Propyl-Thyracil) or methimazole (Tapazole). Alternative treatments include radioactive iodine, which destroys the thyroid with radiation, or removing part of the thyroid gland with a surgical procedure called subtotal thyroidectomy.



• Pheochromocytoma — After medication is given to control symptoms, the adrenal tumor is removed surgically.



• Cardiac arrhythmias — The treatment depends on the cause of the arrhythmia. In some people, massaging the carotid sinus in the neck will stop the problem. Other people require medications such as digitalis (Lanoxin), beta-blockers, calcium channel blockers, quinidine (Cardioquin and other brand names) or flecainide (Tambocor). Some patients respond only to radiofrequency catheter ablation, a procedure that destroys the area of abnormal heart tissue that is triggering the tachycardia. Other patients can be treated with electrical cardioversion, a procedure that delivers a timed electrical shock to the heart to restore normal heart rhythm.



• Coronary artery disease — Coronary artery disease can be treated with medication (nitrates, beta-blockers, calcium channel blockers, aspirin), coronary artery bypass surgery or balloon angioplasty.



• Heart valve abnormalities — Severe heart valve abnormalities usually require that the damaged heart valve be replaced surgically.



• Lung disease — If the tachycardia is caused by a blood clot in the lungs, the usual treatment is medications that dissolve the clot and keep more clots from forming. Pneumonia or other lung problems can be treated with medications for those conditions.

Call your doctor if you experience unexplained tachycardia, not the normal increase in heart rate after exercise. This is especially important if you also have palpitations, dizziness, lightheadedness, fainting spells, fatigue, breathlessness or chest pain.

The long-term outlook is usually good when tachycardia is caused by fever, blood loss, hyperthyroidism, medication or diet. Many tachycardias related to heart or lung problems can be controlled with medication, surgery or other procedures.

American Heart Association (AHA)
7272 Greenville Ave.
Dallas, TX 75231
Toll-Free: 1-800-242-8721
http://www.americanheart.org/

National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: 301-592-8573
TTY: 240-629-3255
Fax: 301-592-8563
Email: nhlbiinfo@rover.nhlbi.nih.gov
http://www.nhlbi.nih.gov/

American College of Cardiology
Heart House
9111 Old Georgetown Road
Bethesda, MD 20814-1699
Phone: 301-897-5400
Toll-Free: 1-800-253-4636, ext. 694
Fax: 301-897-9745
Email: resource@acc.org
http://www.acc.org/