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What is Tachycardia?
Tachycardia means a fast heart rate. The normal adult
heart rate, or pulse, ranges from 60 to 100 beats per minute. A heart rate that
continues to beat above 100 beats per minute is called tachycardia.
Tachycardia can occur naturally, for example, when you
are exercising. It can also be caused by serious, life-threatening heart
problems.
How does it occur?
Your heart rate normally increases in several
situations, such as when you:
Hyperthyroidism (too much thyroid hormone in your body)
can cause a fast heartbeat. Problems with the heart that can also cause
tachycardia are:
- Paroxysmal atrial tachycardia (PAT) and supraventricular
tachycardia (SVT): These forms of tachycardia are disturbances in the
natural electrical impulse that causes your heart to pump. The problem occurs
above the ventricles (the lower chambers of your heart). If you have PAT or SVT,
it does not necessarily mean that you have a serious heart problem.
- Atrial fibrillation: This is an abnormal rhythm pattern where the right
and left atria (upper heart chambers) are contracting irregularly and making the
heart beat faster.
- Ventricular tachycardia: This is a less common, but more dangerous kind of
tachycardia. The heart beats in a regular rhythm but very fast. This abnormality
is caused by heart disease. In a few cases it can be due to medication you are
taking, such as digitalis or quinidine. The problem starts in your ventricles
(lower heart chambers). The most serious aspect of ventricular tachycardia is
that it can become ventricular fibrillation.
- Ventricular fibrillation: This is the most serious type of tachycardia. Your
heart beats in an irregular rhythm and very fast. Your ventricles contract
(squeeze) chaotically, which prevents the heart from pumping. When this
happens, blood circulation stops. Sometimes the episodes are brief and suddenly
go away. Most often, however, ventricular fibrillation requires immediate
medical treatment to prevent brain damage or death.
- Mitral valve prolapse: This mild deformity of one of the valves in your
heart can cause a fast heart rate.
What are the symptoms?
The main symptom is the sensation of a fast heartbeat.
Other symptoms of tachycardia that may require medical treatment are:
These symptoms may be caused by any type of tachycardia,
mild to severe. The more serious the tachycardia is, the more severe the
symptoms are. Contact your health care provider if you are having any of these
other symptoms in addition to the fast heartbeat.
How is it diagnosed?
Your health care provider will study your medical
history and examine your heart and lungs. Blood tests may be done to check for
underlying metabolic diseases, such as thyroid disease. A chest x-ray and
electrocardiogram (ECG) will be done. An ECG measures the electrical activity
of your heart and displays the measurements on a screen or paper. Usually a
rhythm strip is done; this is a continuous ECG for 1 to 2 minutes to look for
heart rhythm abnormalities.
Your health care provider may want you to wear a Holter
monitor for 24 to 72 hours. The Holter monitor is a portable ECG used to detect
heart rhythm disturbances. If your tachycardia seems related to exercise, you
may need to have an ECG while exercising on a treadmill.
How is it treated?
The treatment depends on which type of tachycardia you
have. Treatment may range from exercise conditioning to control of anxiety
symptoms. It may include medication.
Electrical shock may be necessary with atrial
fibrillation, and especially with ventricular tachycardia and ventricular
fibrillation. Implanted electroshock units are now being used for some people
with a high risk of having ventricular fibrillation. In cases of
life-threatening heart rhythm problems, these units could provide instant,
life-saving electrical shock before medical help arrives.
What can I do to help prevent tachycardia?
The best prevention is to have a heart-healthy
lifestyle:
- Maintain a healthy weight.
- Eat a healthy diet.
- Get regular exercise, as recommended by your health care
provider.
- Don't smoke.
- Seldom use other stimulants, for example, caffeine.
- Have regular medical check-ups after age 40.
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