|Terminology: Atrial fibrillation is also called AF, AFib and a quivering heart.
What Is Atrial Fibrillation?
Atrial fibrillation is a type of arrhythmia that causes an irregular and often abnormally fast heart rate. A normal heart rate is between 60 and 100 beats a minute at rest. With atrial fibrillation it can be over 140 beats a minute (you can measure your heart rate by feeling the pulse in your neck or wrist). Atrial fibrillation is the most common type of arrhythmia in the United States, affecting between 5 and 10 percent of all Americans over 65. In most cases it is not life threatening but it can be distressing and uncomfortable. It nearly always needs some form of treatment.
What Are The Symptoms?
The symptoms can vary widely depending on the type of atrial fibrillation you have. The condition is categorized by the degree to which it affects you. The categories are:
Paroxysmal atrial fibrillation: Palpitations come and go without treatment. They may last a few seconds to a few days before subsiding spontaneously.
Persistent atrial fibrillation: Lasts longer than 7 days, or less if treated.
Longstanding persistent atrial fibrillation: Lasts longer than a year.
Permanent atrial fibrillation: Symptoms are continual and do not respond to treatment.
When there are no symptoms: Some people may experience no symptoms and their condition is only discovered during a routine health screening or while testing for another condition. The most obvious sign of atrial fibrillation is a fast and irregular heartbeat which occurs suddenly. Some patients describe their symptoms as a 'heart flip-flop, skipped heartbeat' or 'feels like my heart is banging against my chest'. You may also experience:
Because of the way atrial fibrillation causes the heart to beat, the heart's performance is impaired. This can result in low blood pressure and even heart failure. If you notice a sudden change in your heart beat accompanied by chest pain, seek immediate medical attention.
See also: symptoms of arrhythmia
What Is Happening To My Heart?
When your heart starts to race at rest it means that it’s pumping action has become chaotic. Instead of beating calmly and rhythmically it beats quickly and chaotically, even skipping occasional beats. So what's happening? The two upper chambers of the heart (atria) are beating irregularly, out of coordination with the two lower chambers (ventricles). Normally the atria and ventricles work together, to collect deoxygenated blood from the body, and to return oxygenated blood back again. But with atrial fibrillation, the electrical impulses which co-ordinate the heart's pumping action become temporarily confused (or permanently confused in those with more severe forms of atrial fibrillation). As a result blood flow around the body is affected. This can lead dizziness and shortness of breath. Most cases of atrial fibrillation that come and go are not dangerous. It is only when you have chronic (ongoing) atrial fibrillations that complications may arise.
What Causes It?
The causes are not yet fully understood. It occurs when the heart's electrical impulses start firing irregularly. These impulses override the hearts natural pacemaker which no longer seems able to control the heart's rhythm. Atrial fibrillation can occur in the absence of heart disease. However, it has been linked to:
• Hypertension (high blood pressure)
• Coronary heart disease (CHD)
• Lung diseases such as emphysema
• Thyroid disease (overactive thyroid)
• Pericardial disease
• Mitral valve disease
• Sleep apnea
• Heart damage, due to a heart attack or heart surgery.
See also: causes of arrhythmia.
How Is It Diagnosed?
If you feel your pulse and it is racing when at rest, this is a good indication you may have atrial fibrillation. However, only proper diagnostic tests can diagnose the condition conclusively. Your doctor will refer you to a cardiologist (heart specialist) who will carry out one or more of the following tests:
• Electrocardiogram (ECG)
• Echocardiogram (Echo)
• Holter monitor
• Event monitor
• Blood tests: To rule out thyroid problems and other conditions that may lead to atrial fibrillation.
• Chest X-ray: To rule out other conditions that may explain your symptoms.
See also: diagnosis of arrhythmias.
What Complications Can It Cause?
Heart failure: If untreated, atrial fibrillation can chronically increase in your heart rate, eventually weakening the heart and leading to heart failure. Most people seek treatment before this occurs.
Stroke: It can cause blood to pool in the atria and blood clots to form. If a clot travels from the heart to the arteries that supply blood to the brain, it can lead to a stroke. 15 percent of all strokes occur in people with atrial fibrillation. Atrial fibrillation increases your risk of a stroke by 5 percent a year. Taking warfarin, a blood thinner, can reduce this risk by two thirds.
How Is It Treated?
The treatment you are offered will depend on how severe your condition is. Generally the aim of treatment is to (1) restore normal heart rhythm and (2) prevent blood clots from forming.
1. Restore Normal Heart Rate
Cardioversion is a medical term to describe the restoration of normal heart rhythm. This can be done chemically with drugs or electrically with an electric shock. Certain antiarrhythmics medications, taken either intravenously or orally can help return a normal heart rhythm. If they work, you will be prescribed pills indefinitely. If they don't work you may be recommended electrical cardioversion. This is a brief procedure performed under sedation, whereby an electric shock is delivered to your chest to 'reboot' the heart's rhythm. In 90 percent of cases, the heart is successfully restored to a natural rhythm; although 50 percent of cases relapse within a year so it may have to be repeated. After electrical cardioversion you will be given an antiarrhythmic medication to take indefinitely: such as Sotalol (Betapace), Amiodarone (Cordarone, Pacerone), Propafenone (Rythmol), Dronedarone (Maltaq), Flecainide (Tambocor) and Dofetilide (Tikosyn).
Sometimes medications or electric shock fail to reset the heart's electrical pulses. In this instance the cardiologist may recommend destroying the part of the heart tissue that causes the erratic signals. To do this, he could recommend radiofrequency catheter ablation or maze surgery.
Radiofrequency catheter ablation: A catheter (long thin tube) is directed through an artery in the groin towards the heart. Once in place, radiofrequency energy is emitted which burns and destroys part of the heart's tissue. This normally corrects the heart's rhythm without need for further medicines or implantable devices like an artificial pacemaker or implantable cardioverter defibrillator (ICD).
Maze surgery: Reserved for only the most severe cases because it requires open heart surgery. The chest bone is cut open and the heart is exposed. The surgeon makes a series of cuts in the heart to create a maze pattern of scarring that directs electrical impulses into the ventricles and blocks unnecessary additional impulses.
2. Preventing Blood Clots
In addition to taking antiarrhythmics, your doctor is likely to prescribe medications to reduce your risk of stroke. These include Warfarin (Coumadin), a powerful anticoagulant; Dabigatran (Pradaxa) and Rivaroxaban (Xarelto). Even if your heart beat is returned to normal by drugs or surgery, you are still likely to require an anticoagulant for life. This is because you can have spells of atrial fibrillation and not know it.