Abnormal rhythms of the atria

Several kinds of abnormal heart rhythm (arrhythmia) occur in the heart's upper chambers (the atria). These include atrial fibrillation, atrial flutter, atrial tachycardia, and paroxysmal atrial tachycardia or paroxysmal supraventricular tachycardia.

Atrial fibrillation is a common heart rhythm disturbance. More than 2.5 million Americans have it. Instead of forcefully contracting in a coordinated manner, the walls of the left and right atria quiver and do not effectively pump blood into the ventricles.

Sometimes atrial fibrillation comes and goes, and sometimes it stays constant. As with many heart rhythm abnormalities, atrial fibrillation is often caused by coronary artery disease.

It can occur in people who have otherwise healthy hearts, but it is more common in those who have a heart valve disorder, an overactive thyroid gland, lung disease, a blood clot lodged in a lung, and inflammation of the heart's lining.

Atrial fibrillation is important for three reasons:

• It can signal the presence of another disorder.
• The heart pumps blood less efficiently, making it work harder.
• Blood can pool in the atria and form clots. Such clots can travel from the heart and lodge in an artery in another part of the body. If one of these clots blocks a vessel in the brain, it can cause a stroke. Atrial fibrillation causes about 15% of all strokes.

Atrial flutter is similar to atrial fibrillation, but the contractions of the atria are more regular. They are still not as efficient as they should be at moving blood from the atria into the ventricles. In atrial flutter, the heart can be forced to beat at a dangerously fast rate. Although they are two different rhythm abnormalities, atrial fibrillation can develop and coexist in people who have atrial flutter.

Tachycardia means that the heart beats faster than it should. Atrial tachycardia occurs when electrical impulses are generated from somewhere in the atria other than the sinoatrial (SA) node—the heart's natural pacemaker. The result is a faster-than-usual but very regular heartbeat.

When this condition comes on suddenly and lasts between a few seconds to several hours, it is called paroxysmal atrial tachycardia or paroxysmal supraventricular tachycardia. These are often the result of a disruption in the heart's triggering signal as it travels through the atrioventricular node. The condition can occur in people who have no underlying heart disease, often during emotional stress. It is aggravating, but is usually not a serious problem. It also can occur if you are born with unusual electrical pathways in your heart, in which case it can be a more serious problem.

Wandering atrial pacemaker and multifocal atrial tachycardia are examples of atrial rhythm disturbances in which frequent, unpredictable beats arise from different areas of the atria. These disturbances are usually an indication of lung or heart disease, serious metabolic disturbances, or toxicity of certain medicines.

Symptoms

Abnormal rhythms of the atria may cause no symptoms at all. Some people feel palpitations—the sensation that your heart is racing at a fast pace, fluttering, or "flip-flopping."

It is very common for people to feel palpitations. Palpitations alone are no cause for alarm. However, if the abnormal rhythm is making the heart pump less efficiently, these symptoms may appear:

• fatigue
• breathlessness
• dizziness
• chest pressure or tightness.

If you have these symptoms along with palpitations, call your doctor.

Diagnosis

The main way to detect an abnormal heart rhythm is with an electrocardiogram. This test uses a series of pads placed on the body to analyze the heartbeat.

If the rhythm comes and goes, you may need to wear a Holter monitor, which records every heartbeat for 24 hours. Some people need to use an event monitor for days or weeks. Newer versions can be implanted in the chest.

Treatment

Wandering atrial pacemaker and multifocal atrial tachycardia usually do not cause serious symptoms or require treatment.

Attacks of atrial tachycardia or paroxysmal atrial tachycardia can often be stopped by various maneuvers you can perform yourself (see Home Remedies for Paroxysmal Atrial Tachycardia). If these don't work, drugs such as beta blockers or calcium channel blockers can prevent or abort an attack.

Atrial fibrillation or atrial flutter require immediate treatment if you are having chest pain or heart failure or your heartbeat is very fast. The ideal treatment for atrial fibrillation is to reestablish a normal heart rhythm and then maintain it with the use of medicines.

There are several ways to reestablish a normal rhythm. One of the most effective is cardioversion. This is a carefully administered electrical shock to the heart that interrupts the abnormal heart rhythm and "reboots" the pacemaker, allowing for a normal rhythm.

Sometimes a beta blockers or medication called amiodarone can bring the heart rate back to normal. When the abnormal rhythms are caused by abnormal electrical pathways in the heart and cannot be successfully treated with drugs, your doctor may recommend a treatment called radiofrequency ablation.

In this procedure, a small wire called a catheter is threaded into the heart. Radio waves from the tip of the catheter destroy the abnormal pathways.

An implantable device can be used to detect recurring atrial fibrillation and deliver a small shock to the heart to make the rhythm regular again. This is similar to an implantable defibrillator used to correct abnormal rhythms of the ventricles.

If your heart won't stay in a normal rhythm, there are two main treatment options:

The first choice is usually rate control. Medications such as beta blockers, digitalis, and calcium channel blockers can keep your heart rate from going too fast. Your symptoms should disappear once the drugs begin to control your heart rate.

Another option is rhythm control. Various medications can bring the heart rhythm under control. However, these can be risky due to serious side effects and the necessity for heart monitoring when starting some of them.

In addition, most people with atrial fibrillation need to take warfarin or other blood-thinning medications to prevent formation of potentially stroke-causing blood clots in the atria.