Atrial Fibrillation (AF) is an abnormality in the rhythm of the heart that can cause an irregular and often abnormally fast heart rate. The heart’s rhythm is regulated by electrical impulses. A normal resting heart rate is between 60 and 100 beats a minute when you are resting, and is regular. Heart rate can be measured by feeling the pulse in the wrist or neck. When the heart is in atrial fibrillation, the heart rate may be over 140 beats a minute, although it can be any speed.
When you are in atrial fibrillation, you are unable to assess when the next heart beat will come along as the heart rate is irregular. When the heart beats normally, its muscular walls tighten and squeeze to force blood out and around the body. When they relax, the heart fills with blood again and this process occurs every time the heart beats. In atrial fibrillation, the upper chambers of the heart contract randomly (fibrilate) and sometimes so fast that the heart muscle cannot relax properly causing the heart to be less efficient.
Types of Atrial Fibrillation
Paroxysmal AF – comes and goes and usually stops within 48 hours without any treatment
Persistent AF – episodes last longer that seven days or less when treated
Longstanding persistent AF – continuous for a year or longer
Permanent AF – present at all times and no more attempts to restore normal heart rhythm will be made
- Shortness of breath
- Chest pain (angina)
- Low blood pressure
- Heart failure
Some people do not experience any symptoms and the condition is only diagnosed during routine tests or investigations.
There are many different causes of atrial fibrillation, some are listed below. However, for some people there may appear to be no obvious reason.
- Age – risk increases as we get older. It affects around 10% of people over the age of 75
- Atherosclerosis - a disease of the arteries caused by a build up of fatty material on their inner walls of the artery
- High blood pressure
- Heart valve disease
- Too much alcohol
- Diet pills
- Overactive thyroid gland
- Lung disease such as chronic bronchitis and pneumonia
Risk factors for Atrial Fibrillation
In Atrial Fibrillation, blood may pool (stagnate) due to inefficient pumping in the upper chambers of the heart. When this happens clots can form. If they break off, they can travel into the blood supply to the lungs, or to the brain where they cause a stroke. This type of stroke is called an ischemic stroke.
The main complication of the condition is an increased risk of stroke as blood clots can block arteries in the brain. Atrial fibrillation increases the risk of stroke by around five times.
Anticoagulants are prescribed as a preventative measure to reduce the risk of blood clots developing.
Oral anticoagulants include:
- Apixaban - factor Xa inhibitor
- Edoxaban - factor Xa inhibitor
- Dabigatran - direct thrombin inhibitor
- Rivaroxaban - factor Xa inhibitor
- Warfarin – Vitamin K Antagonist (VKA)
Anticoagulant therapy does not treat the symptoms of AF but helps to reduce your risk of stroke.
Treatments for AF may include:
- Medication to control the heart rate or rhythm
- Cardioversion, where the heart is given a controlled electric shock to restore normal rhythm
- Catheter ablation, to prevent atrial fibrillation from occurring
- Fitting a pacemaker to help your heart beat regularly