Tachycardia

What is tachycardia?

Tachycardia means a fast heart rate. The normal adult heart rate, or pulse, ranges from about 50 to 100 beats per minute. A heart rate that stays above 100 beats per minute is called tachycardia.

How does it occur?

Your heart rate normally increases in several situations, such as when you:

• exercise
• have a fever
• are anxious or excited.

Hyperthyroidism (too much thyroid hormone in your body) can cause a fast heartbeat. Problems with the heart that can also cause a fast heart rate are:

• Paroxysmal atrial tachycardia (PAT) and paroxysmal supraventricular tachycardia (PSVT): PAT and PSVT are caused by changes in the natural electrical impulse that causes your heart to pump.
• Atrial fibrillation: The muscles in the upper chambers of the heart (the atria) may tend to quiver. They do not coordinate with the lower chambers of the heart (the ventricles). This affects the ability of the heart to pump blood. It may also cause an increase in your heart rate.
• Ventricular tachycardia (VT): VT is less common, but more dangerous. The heart beats in a regular rhythm but very fast. The problem starts in your lower heart chambers. It usually occurs when heart disease affects the heart muscle. In a few cases it can be due to medicine you are taking. The most serious aspect of VT is that it can become ventricular fibrillation.
• Ventricular fibrillation (VF): This is the most serious type of fast heart rate. Your heart beats in an irregular rhythm and very fast. Your lower heart chambers contract (squeeze) wildly, which keeps the heart from pumping. When this happens, blood is not pumped to the body (cardiac arrest). Sometimes this happens briefly and quickly goes away. Most often, however, VF requires immediate medical treatment to prevent brain damage or death.

What are the symptoms?

The main symptom is feeling a fast heartbeat. Other symptoms of tachycardia that may require medical treatment are:

• lightheadedness or fainting
• nausea
• cold sweat
• shortness of breath
• chest pain.

These symptoms may be caused by any type of tachycardia, mild to severe. Contact your health care provider if you have any of these other symptoms in addition to the fast heartbeat.

How is it diagnosed?

Your health care provider will ask about your medical history, including your symptoms. He or she will examine your heart and lungs. You may have blood tests to check for diseases such as thyroid disease. You may have a chest x-ray. You will have an electrocardiogram (ECG), which measures the electrical activity of your heart.

Your health care provider may want you to wear a Holter monitor for 1 to 3 days, or to carry another type of monitor with you for several weeks. 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 include medicine, radiofrequency ablation, or implantable cardiac defibrillators (ICDs).

ICDs are used for some people with a high risk of having ventricular fibrillation. In cases of life-threatening heart rhythm problems, ICDs can 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.
• Limit caffeine and other stimulants.
• Have regular medical checkups after age 40.