Atrial Fibrillation

 I have just had a test for irregular heartbeats and been told that I have atrial fibrillation. What is this?

Atrial fibrillation is a very specific irregular heartbeat. The heart works like an electric circuit. There is a master switch at the top of the heart in one of the upper chambers, the atria.

This switch regulates the speed of the heartbeat and normally controls how and when the heart beats, by sending messages to the muscle pump (ventricle) which is located below the atria. When the atria fibrillate, this means that the master switch is no longer in charge, discipline is gone, and chaos reigns. Atrial fibrillation occurs at around 600 beats per minute (bpm) and the top chamber (atrium) resembles a wriggling bag of worms. The heart muscle (ventricle) could therefore, in theory, be bombarded with 600 bpm and would cease to work.

Fortunately below the master switch there is a junction box (called the AV node) which prevents all 600 beats getting through to the heart muscle, so the heart beats at anything up to about 180 bpm, at the rate the junction box will allow.

Medication is used to further block beats through this junction box so that the rate will settle to a more normal and pleasant 70–80 bpm. Doctors refer to the fibrillation being ‘poorly controlled’ or ‘well controlled’, depending on the rate achieved after medication. Good control is when the heart beats at less than 90–100 beats per minute.

Atrial fibrillation (a fluttering feeling) is quite common and, for most people who get it, unavoidable. It responds to treatment and, although the heart is beating less efficiently than a normal regular heart rhythm, it can be improved, so that for most people it is hardly noticed. For a small number of people, it can be difficult to control and they will need to be looked after carefully.

I have been diagnosed as having atrial fibrillation. What could have caused this?

It occurs in many conditions and, in a small number of people, for no obvious reason: so-called ‘lone fibrillation’. It may be a part of getting older (wear and tear to the heart) but it can be a consequence of:

 

  • Mitral valve disease;
  • High blood pressure;
  • Coronary heart disease;
  • Heart failure;
  • An overactive thyroid gland.

 

Alcohol can cause atrial fibrillation in alcoholics but can also induce it in quite normal people when they have been celebrating a little too much, particularly in women, who are more sensitive to alcohol.

How will I know that the palpitations are due to atrial fibrillation?

Atrial fibrillation may come on suddenly and fast. It is usually felt as palpitations of a rapid sort, with the heart ‘beating all over the place’. It can bring on chest pain but usually makes people breathless.

Naturally, it can be frightening, and may leave a feeling of light-headedness if it is so fast that the blood pressure drops a little.

Fibrillation in some people with heart failure can come and go and, as fibrillation is less efficient than normal rhythm (‘sinus rhythm’), this can lead to periods of fatigue and breathlessness. For people who have atrial fibrillation regularly, it is important to keep the rate under control, or the efficiency of the heart and general well-being will be impaired.

My husband has just been told that he has atrial fibrillation. Is this dangerous and can anything be done to help him?

The short answer is: occasionally yes, it can be dangerous, but usually it is not. If he is given modern treatment, the efficiency of his heart will be improved, so that he will hardly notice that he has atrial fibrillation. If it comes on suddenly, he may become very breathless, and he may have to go into hospital. If he has an underlying heart problem, atrial fibrillation can cause little clots to form, and he will need blood thinning treatment to stop this, in order to reduce any chance of a stroke.