Heart Rhythm Disorders or arrhythmias

The heart is a hollow organ made of strong muscle that functions as a pump, constantly moving blood throughout the body. The heart also has an electrical system that sets the rhythm for pumping the blood. The rate at which the heart pumps or “beats” varies according to your activity. At rest, your heart may beat about 60 to 80 times a minute; during strenuous exercise, your heart may beat 200 times a minute.

If something goes wrong with the typical heartbeat, the disorder is called an arrhythmia, or rhythm disorder. The most common heart rhythm disorders are:

  • Premature atrial contractions (PACs) or premature ventricular contractions (PVCs) are minor heart palpitations. They feel as though your heart has skipped a beat. In truth, an extra beat occurs sooner than normal. PACs and PVCs are seldom caused by a serious problem, and they rarely lead to one.
  • Bradycardia is an abnormally slow heart rate.
  • Heart block is an abnormally slow heart rate caused by a problem with the electrical impulse conduction through the heart’s upper and lower chambers.
  • Tachycardia is an overly fast rate.
  • Supraventricular tachycardia is characterized by rapid heartbeats that arise in the heart’s upper chambers.
  • Ventricular tachycardia is another rapid heartbeat, though this originates in the lower chambers.
  • Fibrillation is a rapid, uncoordinated beats.
  • Atrial fibrillation is a common arrhythmia, especially among older adults. The arrhythmia comes from the heart’s upper chambers, beating chaotically at 300 to 600 beats a minute.
  • Ventricular fibrillation is a medical emergency. Chaotic electric signals through the lower chambers cause the heart to suddenly quiver and then stop beating. Unless the heart is shocked back into a normal rhythm by a defibrillator, death results.

Causes and symptoms

Reduced blood supply and/or injury to the heart may disrupt the flow of electrical activity in parts of your heart and cause arrhythmias. Some arrhythmias may be caused by abnormal heart muscle cells or scar tissues. These conditions may be the result of inflammation, secondary damage from another cardiovascular disease or aging.

Arrhythmias may occur for no reason; or they may be the result of something that stimulates the heart, such as stress, caffeine, alcohol, tobacco or illegal drugs. In the wide range of causes, other health problems not related to the heart, such as an overactive thyroid, can cause arrhythmias. And, as luck would have it, some people are simply born with an electrical short circuit in their heart.

How serious are arrhythmias?

The heart is not a perfect clock; it does not always tick regularly. Studies among healthy medical students found that about 50 percent of them had PVCs (premature ventricular contractions), minor heart palpitations. In the general population, that 50 percent holds true. More than half of all people have some sort of arrhythmia. The majority are benign, require no treatment and many people are unaware they even have an arrhythmia. The nature of an irregular heartbeat is more important than the pure presence of the arrhythmia.

Arrhythmias are usually livable conditions. The ones that cause patients discomfort are treatable; some are absolutely curable. Others are dangerous and immediately life-threatening.

When you see the electrophysiologists from University of Minnesota Physicians Heart, you are in the hands of experienced cardiologists who have cared for thousands of arrhythmia patients. Medical treatment is usually required if the arrhythmia causes significant symptoms or puts you at risk of more serious complications.


As wide-ranging as the causes may be, so too are the symptoms. Often there are none. The more obvious signs include:

  • Racing heartbeat
  • Fluttering in the chest
  • Slow heartbeat
  • Fatigue
  • Chest pain or tightness
  • Shortness of breath
  • Lightheadedness
  • Dizziness
  • Fainting or near fainting



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