Atrial Fibrillation or Atrial Flutter

The heart muscle is responsible for circulating blood throughout the body and uses electrical signals from within the heart to control the heartbeat. When the electrical system of the heart does not operate as it is supposed to, atrial fibrillation or flutter can develop.

Atrial fibrillation or flutter is a condition in which electrical charges in the heart are sent very rapidly to the upper chambers, causing them to contract rapidly. Some of the electrical impulses stimulate the lower chambers of the heart (the ventricles), causing them to pump faster and less efficiently than normal.

The fast contractions can be intermittent or sustained. The contractions happen so quickly that the walls of the heart quiver. If the rhythm is irregular, the pumping of the ventricles also becomes irregular (atrial fibrillation). If the rhythm of the upper chambers (the atria) is irregular and the rhythm of the lower chambers is either regular or irregular, it is called atrial flutter.

Because the node that conducts electrical currents to the chambers of the heart is unable to conduct electrical impulses at such a fast rate, only some of the impulses get through to the ventricles. The ventricles beat more slowly than the atria.

During atrial fibrillation or flutter, the atria do not completely pump blood into the ventricles. Eventually, some of the blood in the atria starts to stagnate and clot. If these clots break up or break off, they may pass into the left ventricle, travel through the bloodstream and block a smaller artery. If this happens in the brain, it can cause a stroke.

The ventricles pump so fast that they do not completely fill up with blood. The heart is not pumping efficiently, blood pressure may fall, and heart failure can occur.


Symptoms of atrial fibrillation or flutter depend on how fast the ventricles are beating. If the heart rate is less than 120 beats per minute, there may be no symptoms. If the rate is higher, heart palpitations or discomfort in the chest may be present.

Other symptoms may include:

  • Irregular fast pulse, if experiencing atrial fibrillation
  • Regular fast pulse, if experiencing atrial flutter
  • Feeling of weakness
  • Dizziness or faintness
  • Shortness of breath
  • Chest pain, especially in older adults
  • Falling blood pressure, causing shock — rarely. This typically only occurs in people with atrial fibrillation or flutter who also have very severe heart disease

Causes and Risk Factors

Atrial fibrillation or flutter most often is caused by conditions such as rheumatic fever, high blood pressure, coronary artery disease, alcohol abuse, an overactive thyroid gland (hyperthyroidism) or a birth defect of the heart.

Rheumatic fever (which leads to heart valve disorders) and high blood pressure cause the atria to enlarge, making atrial fibrillation or flutter more likely.

Atrial fibrillation and atrial flutter are more common among older patients.


Diagnosis of atrial fibrillation or flutter will generally begin with the physician taking a medical history and performing a physical exam. During the physical exam, the physician will listen to the patient's heart to detect if there is an abnormal heart rate. The patient will also be asked for a detailed description of symptoms, which may suggest the presence of atrial fibrillation or flutter. After the physical exam, the physician may order tests to examine the heart muscle, the blood flow through the heart, and any potential leaking within the heart valves.

If an abnormal heart rate is detected, the physician may order an electrocardiogram (EKG) to confirm it. An EKG is a painless procedure that records the heart's electrical activity.

If the abnormal heart rhythm is intermittent, the patient may need to wear a Holter monitor. This portable device allows the medical team to observe the patient's heart activity over a longer period of time and helps diagnose the condition if the abnormal rhythm happens while the patient is not at the hospital.

Depending on the patient's symptoms and the results of the other diagnostic tests, an echocardiogram may be performed. This noninvasive procedure uses a machine called a transducer that bounces sound waves off the heart and back into the transducer. These echoes are then translated into visual images. If the echocardiogram is inconclusive, imaging tests such as a cardiac MRI or chest X-ray may be used to see if the heart is enlarged. Other diagnostic tests may include electrophysiology studies to look at the electrical system of the heart.


When a person is having atrial fibrillation or flutter, the first step in treatment is to slow the beating of the ventricles so the heart can pump blood more effectively, often using the medication Digoxin. Other drugs may be needed, including a beta blocker (metoprolol or atenolol) or a calcium channel blocker (verapamil or diltiazem). Drugs that prevent clots from forming (anticoagulants) may also be given.

While the atrial fibrillation or flutter may correct itself, steps must often be taken to bring the rhythm back to normal. Frequently, even after the heart rate has been returned to normal or the patient has been given drugs to help control the rhythm, the fibrillation or flutter returns.

The longer the condition is present, the more difficult it becomes to return the heart to a normal rhythm, the more enlarged the upper chambers of the heart can get, and the worse the underlying heart disease can become.

Other treatment approaches include:

  • Delivering an electrical shock to the heart — the most-effective measure to convert the rhythm to normal, as a first step. To prevent the risk of a blood clot, a person may need to take anticoagulants for four weeks before this procedure. The patient's doctor must balance the risk of uncontrolled bleeding against the need to prevent clots
  • Catheter ablation
  • Drugs such as amiodarone, propafenone or sotalol
  • Treatment of the underlying disorder, such as treating an overactive thyroid gland or performing surgery to repair a heart valve or birth defect of the heart.

The knowledgeable and highly trained staff at the Cedars-Sinai Heart Institute will work with each patient to determine the best treatment option.