What Is Atrial Fibrillation?
Atrial fibrillation (AF) is a kind of tachycardia — an abnormally fast heart rhythm. Frequently this arrhythmia is referred to as an irregular heart beat. A normal, steady heart rhythm typically beats 60-80 times a minute. In cases of AF, the rate of atrial impulses can range from 300-600 beats per minute (bpm). These very fast, irregular signals can cause a number of problems. First, the quivering atria no longer pump efficiently, and some blood may stay in the atria with each heartbeat. The pooled blood could possibly clot, increasing the risk of stroke.
Second, the many impulses coming from the atria are trying to follow the electrical pathway to the ventricles and make them contract at the same rate. Luckily, the AV node limits the number of signals that actually reach the lower chambers, so the whole heart usually does not contract at the 300 bpm rate. However, AF can cause your heart to race and does reduce the pumping efficiency. Like other forms of arrhythmia, AF may prevent the heart from pumping enough blood and oxygen to meet your body's needs.
AF is relatively common, affecting about 2-5 million Americans. Unlike ventricular fibrillation, atrial fibrillation is not usually considered life-threatening. However, if AF occurs over a length of time, it can lead to stroke or heart muscle damage congestive heart failure) and accelerated degeneration of the conduction system. People with AF are about five times more likely to have a stroke than the general population. This arrhythmia is responsible for 15-20% of all strokes.
What Are Causes and Risk Factors of Atrial Fibrillation?
Precise causes of atrial fibrillation can be difficult to identify. High blood pressure and coronary artery disease are associated with AF, as are other heart and lung conditions such as disease of the heart valves, chronic lung disease, and congestive heart failure. Otherwise normal hearts influenced by alcohol, stress, caffeine, severe infections, or some drugs may experience AF. Sometimes, no underlying cause is identified. As you grow older, the risk of AF seems to increase, especially after age 60. Having a relative with atrial fibrillation does increase your risk of having atrial fibrillation.
The cause of AF is though to be from the pulmonary veins. These veins, typically four, bring the blood, after it has picked up oxygen, from the lungs into the left atrium. Atrial fibrillation is thought to occur in stages and the earlier it is caught the more treatment options exist.
What Are Symptoms of Atrial Fibrillation?
Symptoms of atrial fibrillation vary, so not everyone feels the same thing during AF. Some people with AF experience palpitations, a sudden fluttering or pounding in the chest. Sometimes, because your heart is not pumping efficiently during AF, you may feel dizzy, faint, or short of breath. Some people have no symptoms at all.
While AFib is not life-threatening in itself, it should be treated to minimize the risks that are associated with it. These risks include:
- Other rhythm problems
- Chronic fatigue
- Congestive heart failure
During AFib, the left atrium doesn’t completely empty of blood; the remaining blood can become stagnant and clot. If a clot travels into the ventricle and out into the bloodstream, it can block an artery, causing a stroke. In fact, the risk of having a stroke is 5 times greater for people with AFib than for others. Between 15% and 20% of all strokes occur in people with AFib.
How Is Atrial Fibrillation Diagnosed?
To diagnose AF, your doctor will typically use an electrocardiogram (EKG) test. In this snapshot, it allows the physician to identify what heart rhythm you are currently in. Occasionally, a Holter or Event recorder needs to be placed. These simple monitoring devices are able to worn for long periods of time and may detect AF, or other heart rhythm disorders, when they are not always present. They are very usefully in patients that have intermittent symptoms, and in detecting early atrial fibrillation.
What type of AF do I have?
Atrial fibrillation is divided into categories to better delineate the treatment regimen. Most people believe that this is a continuous spectrum and the earlier on the spectrum the more successful certain therapies are.
There are 3 types of AFib:
- Paroxysmal AFib occurs in short, intermittent episodes. The abnormal rhythm usually converts back to normal within a short time - from a few seconds to a few hours.
- Persistent AFib does not convert back to normal rhythm on its own. Medical treatment is needed to stop the AFib.
- Permanent AFib occurs when the heart is always fibrillating. This condition is accompanied by symptoms that cause discomfort and an increased risk of stroke. Treatment is required.
The type of atrial fibrillation will determine the therapy and the success of the therapy.
How Is Atrial Fibrillation Treated?
Treatment for AF depends greatly upon you and your symptoms, how long you have atrial fibrillation and in what stage the atrial fibrillation is in. There are several important features to atrial fibrillation that are important to address:
- How fast is your atrial fibrillation going? Generally a 24- hour monitor is placed to understand how well your drug therapy is working.
- How far along is your atrial fibrillation: Curative treatment options are available for the treatment of atrial fibrillation however, this will be determined by a number of issues included in the work-up.
- How healthy are you otherwise? While all these treatment regimens are available you should be healthy enough to undergo these therapies. In other words the treatment regimen needs to be customized to you.
- What is your stroke risk? We know that patients with atrial fibrillation are at risk for strokes, however treatment for the prevention of stroke patients maybe on coumadin. Like all medications and medical procedures the risks of side effects needs to be addressed and understood. We will review with every patient what their stroke risk profile is.
Generally, your doctor will focus on treatments that help control your heart rate and reduce the risk of blood clots. Blood thinners, such as aspirin or warfarin, are commonly prescribed. Several antiarrhythmic medications that help control episodes of rapid heart rhythms also are available. The choice of which drug may help you is very individual. Because most of the medications work only some of the time, your doctor may need to try other drugs if you experience continued symptoms or unwanted side effects. It is very important to understand the side effects of these antiarrhythmics medications because they are potentially harmful. Careful monitoring of the medications maybe needed to avoid serious side effects.
Other treatment options for atrial fibrillation include catheter based ablation therapy and AV node ablation with pacemaker insertion. Catheter ablation is a minor surgical procedure similar to angiogram. AV node ablation with permanent pacemaker insertion is a procedure reserved for very ill patients, patients with long standing atrial fibrillation and enlarged atria, or those patients with multiple arrhythmias that can not be controlled with medical therapy or a curative ablation technique. Because heart rate control is important in patients with long standing atrial fibrillation this maybe an option if the heart rate is not well controlled.