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A rapid heartbeat is defined as a heart rate that is faster than normal. The heart normally beats fewer than 100 times per minute in adults. In children, the heart can beat slightly faster than 100 times per minute and still be considered normal.

What is going on in the body?

At rest, a person's heart rate usually stays within a standard range. This range is usually 50 to 100 times per minute in adults and slightly faster in children. With increased physical activity, stress, or other conditions, however, the heart rate may increase above the normal level.

What are the signs and symptoms of the condition?

A person with a rapid heartbeat may have no symptoms at all. When symptoms do occur, they may include:

• palpitations, that is, an unusual awareness of the heartbeat
• excessive sweating
• fatigue or weakness
• shortness of breath
• chest pain
• lightheadedness or dizziness
• fainting
• symptoms related to the cause of the rapid heart rate

What are the causes and risks of the condition?

There are many possible causes of a rapid heartbeat, including:

• exercise, heavy lifting or other activity that requires exertion
• fear, pain, anxiety, stress, anger, or nervousness
• fever
• dehydration. This may be caused by too little intake of fluids, loss of blood, diarrhea, vomiting, or medications such as diuretics, sometimes called "water pills."
• low blood pressure, also called hypotension
• hyperthyroidism, which is a level of thyroid hormone in the body that is too high
• congestive heart failure, a condition in which the heart cannot pump blood effectively
• irregular heartbeats, known as arrhythmias, such as atrial fibrillation or ventricular tachycardia. These may be caused by salt imbalances, heart attack, and other conditions.
• anemia (a low red blood cell count)
• medications or drugs. Albuterol (i.e., VoSpire ER, AccuNeb, Proventil, ProAir HFA, Ventolin HFA), which is commonly used to treat asthma, as well as some over the counter and prescription decongestants can cause rapid heartbeat. Cocaine abuse and alcohol withdrawal are other causes of rapid heartbeat.
• excessive caffeine intake
• some herbal therapies such as ephedra, also called ma huang
• infections. These may include such as a serious blood infection called sepsis and pneumonia.
• nerve damage, known as peripheral neuropathy, that affects the nerves attached to the heart. This is often due to diabetes, a condition that results in a high level of blood sugar.
• low oxygen in the blood, also called hypoxia. There can be many causes for this, such as asthma and emphysema.

Other causes are possible. Sometimes, no cause can be found.

What can be done to prevent the condition?

Prevention is related to the cause. Many cases cannot be prevented. In most people, regular exercise is advised even though it causes a rapid heartbeat. In this case, prevention is not an issue. Avoidance of cocaine or alcohol can prevent cases from these drugs. Getting enough fluids can prevent many cases due to dehydration.

How is the condition diagnosed?

The speed of the heartbeat usually can be measured by checking the pulse or listening to the heartbeat with a stethoscope..Diagnosis of the cause starts with a history and physical exam.

The healthcare professional may order tests such as:

• electrocardiogram (ECG), to help diagnose irregular heartbeats and heart attacks
• chest x-ray
• echocardiogram, or an ultrasound of the heart, to help diagnose congestive heart failure
• thyroid function tests to diagnose high thyroid levels
• arterial blood gases to measure oxygen levels in the blood

What are the long-term effects of the condition?

If the heart beats too quickly, it may not be able to pump blood well enough to keep a person alive. Most long-term effects are related to the cause. For example, rapid heartbeat due to anxiety or exercise often goes away quickly and has no long-term effects. Rapid heartbeat due to an arrhythmia or sepsis may sometimes result in death.

What are the risks to others?

A rapid heartbeat is not contagious and poses no risks to others. If the cause of the rapid heartbeat is an infection, the infection may be contagious.

What are the treatments for the condition?

Treatment is directed at the cause. For example, someone who is dehydrated can be given fluids. A person with a fever may be given acetaminophen (i.e., Tylenol). Someone with an infection may need antibiotics or surgery. An individual with an arrhythmia may need heart medications to slow the heart rate, such as atenolol (i.e, Tenormin) or lidocaine (i.e., Xylocaine).

What are the side effects of the treatments?

Potential side effects depend on the treatments used. For example, antibiotics may cause allergic reactions or stomach upset. Surgery can be complicated by infection, bleeding, or reactions to anesthesia.

What happens after treatment for the condition?

The heartbeat usually returns to normal after treatment of the cause. For example, when fever, infection, or pain are the cause, no further treatment for the rapid heartbeat is needed if these condition go away. Someone with congestive heart failure or diabetes, however, often needs lifelong treatment and monitoring.

How is the condition monitored?

The speed of the heartbeat can be monitored closely if needed. This is done with special equipment that measures the electrical activity in the heart. Other monitoring is related to the cause. For example, those with a heart attack may need close monitoring in the intensive care unit.