Atrial fibrillation (AF) is an arrhythmia (abnormal heart rhythm) that causes the heart’s upper chambers-the atria- to beat very fast and irregularly. It is quite rare in children but can occur in children with cardiomyopathy, after complex heart surgery, and very rarely, in children with otherwise normal hearts.
An arrhythmia is an abnormal heart rhythm caused by a problem in the heart’s electrical system, also called the conduction system. During an episode of atrial fibrillation, many electrical impulses quickly around the atria causing the atria to contract in such a fast and chaotic fashion that they quiver "like a bowl of jelly". Fortunately, the AV node blocks most of the impulses from reaching the lower chambers-the ventricles. So, even though the atria are beating very fast, the ventricular heart rate (which causes the "pulse") beats at a slower rate, usually less than 180 beats per minute. Sometimes the pulse rate is lower and may even be in the normal range but it will still be irregular.
The frequency and severity of episodes of atrial fibrillation can vary widely. In some people, the episodes occur rarely and they may stop on their own. In other cases, medical treatment is needed to restore a normal heart rhythm. Rarely, the arrhythmia does not return to normal with medical treatment and the person remains in chronic atrial fibrillation. In this case, long-term treatment with medicines is needed to manage the symptoms.
During atrial fibrillation, there is an increased risk that blood clots will form inside the atria that, if dislodged, could cause a stroke. Medications called "blood thinners" such as warfarin are used to prevent the blood clots from forming.
Symptoms: Symptoms caused by atrial fibrillation include a feeling of "heart racing", lightheadedness, low energy levels, chest pain, shortness of breath, and/or fainting. Sometimes there are mild or no symptoms.
Physical findings: If the child is having an episode at the time of the exam, the pulse rate will be fast and irregular. If there are other heart problems, the physical findings that go along with that problem.
Medical tests: One of the first tests usually done is an electrocardiogram. This is a safe and painless test that involves putting some stickers across the chest. The stickers are connected to a machine that records the heart’s electrical activity. If the person is having an episode during the ECG, the heart rate will be fast, irregular, and there will be many extra "p" waves from rapid atrial contractions.
In order to diagnose atrial fibrillation, an ECG at the time of symptoms may be helpful. If the symptoms don’t occur regularly, this may be done using a small device called a transtelephonic ECG recorder. These devices can be used at home or at school to record an ECG at the time of symptoms. The tracing is held in the device’s memory until it can be sent over the phone to a cardiology center. Other useful tests include a Holter monitor, echocardiogram, and/or an exercise test. If further testing is needed, a special type of heart catheterization called an electrophysiologic study may be done.
Possible treatments include defibrillation (shock), medications, or, in some cases, radiofrequency ablation or a pacemaker.
Defibrillation restores normal heart rhythm by delivering a large electrical "shock" to the heart. This interrupts the chaotic electrical activity of the atria, resets the conduction system, and allows the normal heart rhythm to resume. Sedation or anesthesia is used to prevent pain that would otherwise occur with this procedure.
Medications used to treat or control atrial fibrillation include amiodarone, flecainide, sotalol, diltiazem, verapamil, and ibutilide. Warfarin (Coumadin) is used to help prevent blood clots from forming in the heart.
Radiofrequency ablation is an option for some patients with atrial fibrillation. This is done during a special type of heart catheterization called an electrophysiologic study. First, the person is given IV sedation or general anesthesia. Then soft, thin plastic tubes (catheters) are placed in the large blood vessels near the groin and are then gently guided or "floated" to the heart. These catheters are used to locate or "map" irritable spots that trigger atrial fibrillation. Once the spots are found, a special type of catheter is used to deliver radiofrequency energy in that area. The energy heats the catheter tip causing a small "burn" with the intent of damaging the irritable spots so they can no longer "fire" electrical impulses.
Atrial fibrillation sometimes occurs in people who have another heart rhythm problem called sick sinus syndrome. Sometimes the sinus node is not healthy so it fires slowly or irregularly. A slow, irregular rate is known to increase the chances of atrial fibrillation and may be treated a pacemaker.
If atrial fibrillation is long-standing and does not respond to other treatment, radiofrequency ablation of the AV node along with placement of a pacemaker may be done. This procedure creates complete heart block at the level of the AV node so that no impulses from the atria can reach the ventricles. A pacemaker is implanted in order to provide a steady, safe heart rate.
The long-term health issues depend on the frequency and duration of episodes, as well as the presence of underlying heart disease. While this is often a chronic problem, there are many effective treatments available.
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Written by: S. LeRoy RN, MSN, CPNP
Reviewed January, 2010