What is atrial fibrillation ?
Atrial fibrillation, also known as 'AF' is the commonest sustained cardiac arrhythmia. Its prevalence increases with increasing years. It is estimated to affect at least 1% of the population at the age of 60 years and 5% at the age of 70 years. It occurs more frequently in those with underlying heart disease. While it is not immediately life-threatening in the same way as sustained ventricular arrhythmias, it can lead to heart failure or stroke and so it has potentially serious effects. In atrial fibrillation, the normal regular rhythmic activity of the upper chambers or atria is replaced by chaotic irregular activity. This leads to an irregular and usually fast pulse rate which may cause palpitations and congestion of the lungs. Also, because the upper chambers no longer contract and relax in the normal way, there may be stagnation of the blood which predisposes to blood clot formation. If a fragment breaks off, it will travel in the blood stream and block a small artery somewhere downstream. The most serious situation is when a clot lodges in an artery in the brain as this can cause a stroke.
The initial assessment
The first step when someone developes atrial fibrillation is to look for any underlying cause or precipitating factors. The history may reveal a background of high blood pressure, heart valve disease or coronary artery disease. Alcohol plays an important role in precipitating atrial fibrillation in many patients. An overactive thyroid gland is another potential cause which must be considered. Often, a chest infection causing irritation around the heart may precipitate atrial fibrillation or certain operations, especially those involving the chest cage. In addition to a careful history and clinical exam, patients will usually have an ECG and ultrasound examination of the heart. Sometimes a coronary angiogram will be considered if there are symptoms suggesting angina or associated breathlessness.
How is atrial fibrillation treated ?
The mainstays of treatment are heart rate medication and some form of medication to minimise blood clot formation. There are a number of different medications available some of which prevent the pulse rate from going too fast and others which have a direct action on the rhythm itself. The medications which reduce the risk of blood clot formation are aspirin, clopidogrel and warfarin. As with all medications. there are potential side-effects and so the risks and benefits must be weighed up carefully before deciding what tablets are started.
One other treatment that may be required to restore the normal regular rhythm is electrical cardioversion. This is a procedure where an electrical shock is delivered through special paddles applied to the chest wall but in a controlled environment, unlike when given during a cardiac arrest like on television. Patients are put to sleep for a few minutes so that they won’t feel any pain or discomfort. Sometimes, even though regular rhythm is restored, the atrial fibrillation may come back so continued follow-up with or without medication is usually required.This is a day procedure and you will be required to fast beforehand due to the mild anaesthesia given to temporarily sedate you.