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Atrial Fibrillation (cont.)

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How is atrial fibrillation (AFib) diagnosed?

Atrial fibrillation can be chronic and sustained, or brief and intermittent (paroxysmal). Paroxysmal atrial fibrillation refers to intermittent episodes of AFib lasting, for example, minutes to hours. The heart rate reverts to normal between episodes. In chronic, sustained atrial fibrillation, the atria fibrillate all of the time. Chronic, sustained atrial fibrillation is not difficult to diagnose. Doctors can hear the rapid and irregular heartbeats using a stethoscope. Abnormal heartbeats also can be felt by taking a patient's pulse.

EKG (electrocardiogram)

An electrocardiogram (EKG) is a brief recording of the heart's electrical discharges. The irregular EKG tracings of AFib are easy to recognize provided AFib occurs during the EKG.

Holter monitor

If episodes of AFib occur intermittently, a standard EKG performed at the time of a visit to the doctor's office may not show AFib. Therefore, a Holter monitor, a continuous recording of the heart's rhythm for 24 hours, often is used to diagnose intermittent episodes of AFib.

Patient-activated event recorder

If the episodes of atrial fibrillation are infrequent, a 24-hour Holter recording may not capture these sporadic episodes. In this situation, the patient can wear a patient-activated event recorder for 1 to 4 weeks. The patient presses a button to start the recording when he or she senses the onset of irregular heartbeats or symptoms possibly caused by AFib. The doctor then analyzes the recordings at a later date.


Echocardiography uses ultrasound waves to produce images of the heart's chambers and valves and the lining around the heart (pericardium). Conditions that may accompany AFib such as mitral valve prolapse, rheumatic valve diseases, and pericarditis (inflammation of the "sack" surrounding the heart) can be detected with echocardiography. Echocardiography also is useful in measuring the size of the atrial chambers. Atrial size is an important factor in determining how a patient responds to treatment for AFib. For instance, it is more difficult to achieve and maintain a normal heart rhythm in patients with enlarged atria.

Transesophageal echocardiography (TEE)

Transesophageal echocardiography (TEE) is a special echocardiographic technique that involves taking pictures of the atria using sound waves. A special probe that generates sound waves is placed in the esophagus (the food pipe connecting the mouth to the stomach). The probe is located at the end of a long flexible tube that is inserted through the mouth into the esophagus. This technique brings the probe very close to the heart (which lies just in front of the esophagus). Sound waves generated by the probe are bounced off of the structures within the heart, and the reflected sound waves are used to form a picture of the heart. TEE is very accurate for detecting blood clots in the atria as well as for measuring the size of the atria.

As previously discussed, blood may clot in the atria during AFib, and pieces of the clot may dislodge and travel to the brain, causing a stroke. Doctors are especially concerned about blood clots dislodging during or after cardioversion (the conversion of atrial fibrillation back into a normal heart rhythm with either drugs or electrical shocks). Moreover, doctors believe that resumption of atrial contractions after successful cardioversion increases the likelihood that pieces of clot will dislodge. For these reasons, anticoagulation (thinning) of blood usually is done prior to cardioversion. This prevents new clot from forming while the old clot dissolves or solidifies so that pieces cannot break off. If no clots are detected in the atria by TEE, the risk of stroke after cardioversion is believed to be lower. Thus, some doctors use TEE to determine the risk of stroke following cardioversion. Studies are underway to determine whether patients with a normal TEE (no blood clots) need to have their blood thinned prior to cardioversion.

Other tests

High blood pressure and signs of heart failure can be ascertained (determined) during a physical examination of the patient. Blood tests are performed to detect abnormalities in blood oxygen and carbon dioxide levels, electrolytes, and thyroid hormone levels. Chest X-rays reveal enlargement of the heart, heart failure, and other diseases of the lung. Exercise treadmill testing (a continuous recording of the EKG during exercise) is a useful screening study for detecting severe coronary artery disease.

Medically Reviewed by a Doctor on 5/4/2015


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