An arrhythmia is a change in the rhythm of your heartbeat. When the heart beats too fast, it’s called tachycardia. When it beats too slow, it’s called bradycardia. An arrhythmia can also mean that your heart beats irregularly (skips a beat or has an extra beat). At some time or another, most people have felt their heart race or skip a beat. These occasional changes can be brought on by strong emotions or exercise. They usually are not a cause for alarm. Arrhythmias that occur more often or cause symptoms may be more serious and need to be discussed with your doctor.

The term arrhythmia refers to any change from the normal sequence of electrical impulses, causing abnormal heart rhythms. This can cause the heart to pump less effectively. Some arrhythmias are so brief (for example, a temporary pause or premature beat) that the overall heart rate or rhythm isn’t greatly affected. But if arrhythmias last for some time, they may cause the heart rate to be too slow or too fast or the heart rhythm to be erratic.

The term tachycardia refers to a heart rate of more than 100 beats per minute. Bradycardia describes a rate of less than 60 beats per minute.

A fast heart rate is called tachycardia. Tachycardias fall into two major categories. Ventricular tachycardia involves only the ventricles. Supraventricular tachycardia involves both the atria and the ventricles. The definition of “too fast” usually depends upon the person’s age and physical activity.

Tachycardia

Under certain conditions, the automatic firing rate of secondary pacemaker tissue may become too fast. If such an abnormal “focus” fires faster than the sinus node, it may take over control of the heart rhythm and cause tachycardia.

In another type of abnormal conduction, impulses get caught in a merry-go-round-like sequence. This process, called reentry, is a common cause of tachycardias. Regardless of their cause, tachycardias are classified by where they arise. Thus, ventricular tachycardias start in the heart’s ventricles (lower chambers). Supraventricular tachycardias arise higher in the heart - either in the upper chambers (atria) or the middle region (AV node or the very beginning portion of the His-Purkinje system.)

Causes of arrhythmia

The heart has 4 compartments, or chambers. The walls of the heart squeeze together (contract) to push blood through the chambers. The contractions are controlled by an electrical signal that begins in the heart’s natural “pacemaker” (called the sinoatrial node). The rate of the contractions is influenced by nerve impulses and hormones in the blood. A problem in any of these can cause an arrhythmia.

Minor arrhythmias may be caused by excessive alcohol use, smoking, caffeine, stress or exercise. The most common cause of arrhythmias is heart disease, particularly coronary artery disease, abnormal heart valve function and heart failure. However, arrhythmias can occur for no known reason.

What are the symptoms of arrhythmia?

Call your doctor if you have any of these symptoms, especially if you have heart disease or have had a heart attack.

  • Palpitations or rapid thumping in your chest.
  • Feeling tired or light-headed.
  • Passing out.
  • Shortness of breath.
  • Chest pain.

How are arrhythmias treated?

Treatment depends on the type of arrhythmia you have. Some mild arrhythmias require no treatment. Other arrhythmias can be treated with medicines. If another health problem is causing the arrhythmia, treatment is aimed at taking care of that problem. In more serious cases, other treatments are available:

  • An artificial pacemaker is an electronic device placed under the skin on the chest. It helps the heart maintain a regular beat, especially when the heart beats too slowly.
  • Cardiac defibrillation (very brief electric shock) can be used to stop an abnormal rhythm and restore a normal one.
  • Surgery can correct certain types of arrhythmias. For example, arrhythmias caused by coronary artery disease may be controlled by bypass surgery. When an arrhythmia is caused by a certain area of the heart, sometimes that part of the heart can be destroyed or removed.

Is an arrhythmia serious?

In most people, arrhythmias are minor and are not dangerous. A small number of people, however, have arrhythmias that are dangerous and require treatment. Arrhythmias are also more serious if you have other heart problems. In general, arrhythmias that start in the lower chambers of the heart (called the ventricles) are more serious than those that start in the upper chambers (called the atria). Your doctor will talk with you about the type of arrhythmia you have and whether you need treatment.

When to Call the Doctor

Although many arrhythmias are minor and don’t represent a significant threat to a person’s health, some can indicate a more serious health problem. If you’ve been having symptoms like those listed above, call your doctor.

Risk factors

Certain factors may increase your risk of developing an arrhythmia. These include:

  • Age. With age, your heart muscle naturally weakens and loses some of its suppleness. This may affect how electrical impulses are conducted.
  • Genetics. Being born with a heart abnormality may affect your heart’s electrical function.
  • Coronary artery disease, other heart problems and previous heart surgery. Narrowed heart arteries, heart attack, abnormal valves, prior heart surgery, cardiomyopathy and other heart damage are risk factors for almost any kind of arrhythmia.
  • Thyroid problems. Your metabolism speeds up when your thyroid gland releases excess hormones. This may cause fast or irregular heartbeats and is most commonly associated with atrial fibrillation. Your metabolism slows when your thyroid gland hormone levels are inadequate, which may cause a bradycardia.
  • Drugs and supplements. Over-the-counter cough and cold medicines containing pseudoephedrine and certain prescription drugs may contribute to arrhythmia development. The herbal supplement ephedra also increases the risk of arrhythmia, but in early 2004, the Food and Drug Administration banned ephedra from the marketplace because of such health concerns.
  • High blood pressure. This increases your risk of developing coronary artery disease. It may also cause the walls of your left ventricle to thicken, possibly altering how your heart’s electrical impulses are conducted.
  • Obesity. Along with being a risk factor for coronary artery disease, obesity may increase your risk of developing an arrhythmia.
  • Diabetes. Your risk of developing coronary artery disease and hypertension greatly increases with uncontrolled diabetes. In addition, episodes of low blood sugar (hypoglycemia) can trigger an arrhythmia.
  • Obstructive sleep apnea. This disorder can cause bradycardia and bursts of atrial fibrillation.
  • Electrolyte imbalance. Electrolytes, such as potassium, sodium, calcium and magnesium, help trigger and conduct the electrical impulses in your heart. Electrolyte levels that are too high or too low can affect your heart’s electrical impulses and contribute to arrhythmia development.
  • Alcohol consumption. Drinking too much alcohol can affect factors that alter the conduction of electrical impulses in your heart or increase the chance of developing atrial fibrillation. In fact, development of atrial fibrillation after an episode of heavy alcohol intake is sometimes called “holiday heart syndrome.” Chronic alcohol abuse may depress the function of your heart and can lead to cardiomyopathy. Both are factors in arrhythmia development.
  • Stimulant use. Stimulants, such as caffeine and nicotine, can cause premature heartbeats and may contribute to the development of more serious arrhythmias. Illicit drugs, such as amphetamines and cocaine, may profoundly affect the heart and lead to many types of arrhythmias or to sudden death due to ventricular fibrillation.

Sources: Medicine Net, Family Doctor, American Hearth

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