What Is It?

Tachycardia is a heart rate of more than 100 beats per minute. In normal adults, the heart beats regularly 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 an abnormally high level of thyroid hormones, called hyperthyroidism, or by an adrenal gland tumor called pheochromocytoma. In some patients, 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. 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.

Although tachycardia is a symptom in itself, it can occur with associated symptoms, such as:

• Dizziness, lightheadedness and (sometimes) fainting
• Fatigue (an abnormally tired feeling due to decreased cardiac output)
• Palpitations (awareness of a rapid heartbeat)
• Breathlessness

If tachycardia is caused by an underlying medical illness, there will be additional symptoms that are specific to that medical 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.

Your doctor will ask about your family history of heart disease and cardiac arrhythmias. He or she also will review your personal medical history, including any possible risk factors for tachycardia (coronary artery disease, heart valve abnormalities, heart valve disease resulting from rheumatic fever, thyroid disorders, medications, dietary factors). You also will be asked to describe your specific cardiac symptoms, including any possible triggers for those symptoms.

During the physical examination, your doctor will check your heart rate and rhythm, together with your pulses. This is because certain cardiac arrhythmias cause a mismatch of the pulse, which reflects the activity of the ventricles, and the heart sounds. Your doctor also will check for an enlarged heart, for heart murmurs (one sign of a heart-valve problem) 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, ambulatory electrocardiography may be required. During ambulatory electrocardiography, you will wear a portable EKG machine called a Holter monitor, 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, echocardiography to rule out heart-valve abnormalities, coronary angiography to rule out coronary artery disease and other tests.

The duration of tachycardia depends on its underlying cause. For example, tachycardia resulting from fever will subside 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 pheochromocytoma will resolve with treatment of the underlying disorder, whereas tachycardia caused by medications or dietary factors will subside quickly, usually within hours, when the chemical that is causing the problem is metabolized or excreted in the urine. Tachycardia caused by cardiac problems can be a long-term problem.

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 (coffee, tea and cola), 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 IV fluids (delivered into a vein) and/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 causes radioactive destruction of the thyroid, or surgical removal of a portion of the thyroid gland with a procedure called subtotal thyroidectomy.
• Pheochromocytoma — After medication is given to control symptoms, the adrenal tumor is removed surgically.
• Cardiac arrhythmias — The specific treatment depends on the underlying 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, beta-blockers, calcium channel blockers, quinidine (Cardioquin and other brand names) or flecainide (Tambocor). Some patients respond to only 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.

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

The long-term prognosis is usually good when tachycardia is caused by fever, blood loss, hyperthyroidism, medication or dietary factors. Many tachycardias related to heart problems can be controlled with medication, radiofrequency catheter ablation or surgery (to correct coronary artery problems or heart-valve abnormalities).

Diseases and Conditions Center

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.