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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(see Chapter 1). 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 breath ¬less. 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.
Tests for atrial fibrillation
My doctor has told me that I have will have to undergo some tests to check to see whether I have atrial fibrillation. What will this involve?
There are several diagnostic tests.
• Your heart may be checked by a standard resting ECG or one taken over 24 hours.
• A chest X-ray may be taken.
• A scan (echocardiogram) can be performed to check the heart valves and muscle pump (see the sectionTestsin Chapter 3).
• Blood may be taken for routine checks and to make sure that your thyroid gland is all right.
In some cases, atrial fibrillation may be part of an illness which needs surgery, such as mitral valve replacement (see Chapter 7), and X-rays of the heart (cardiac catheterisation: see Chapter 3) will be performed before you have to undergo surgery.
You may undergo electrophysiological tests (EPS) studies (see earlier question above) if you have rapid palpitations which cannot be caught on tape, or if you have potentially dangerous palpitations and have palpitations that refuse to respond to safe and normally effective tablets. The reason for these studies is the technique of cardiac ablation (see the section Treatment of atrial fibrillationbelow).
Treatment of atrial fibrillation
What sort of treatment is there available for me now that I have been diagnosed with atrial fibrillation? Can I just be treated with medication?
Following your tests and depending on the severity of atrial fibrillation, you will usually be prescribed medication. People whose atrial fibrillation has only just started may benefit from electric shock treatment.
If you have heart problems and the fibrillation is considered part of your illness, you will be treated with medication to keep your heart rate as steady as possible. To some extent the medication used will depend on the cause.
• If you have heart failure, you may be prescribed digoxin.
• If you have high blood pressure but no muscle pump damage, you may be prescribed a beta-blocker, verapamil or diltiazam.
• Once heart failure is controlled a beta-blocker may be added to digoxin or replace it.
Most people are on a beta-blocker or verapamil (but not if they have heart failure), but some are on more than one medication to get more benefit. It is vital that you know what each type is for (write it down when you are discussing it with your doctor) because, if you stop taking one medication, your heart may race away again. You will help yourself by reducing caffeine, alcohol, stopping smoking and reducing weight.
What medication will I be offered to treat my atrial fibrillation?
Digoxin, beta-blockers (such as atenolol, bisoprolol, propranolol, metoprolol), calcium antagonists (such as verapamil, diltiazem), amiodarone, flecainide, propafenone, disopyramide, quinidine, and combinations of the above. Warfarin is used to thin your blood. See the sectionMedicationin Chapter 5.
I have been told that I am going to have shock treatment for atrial fibrillation. What will this involve and is it dangerous?
If the heart is all right and it appears to have been a temporary upset, you may undergo shock treatment to get the heart back to its regular rhythm.
Electric shock treatment involves passing a high voltage electric current through your heart and is known as cardioversion or a DC shock. It is used to correct rhythm disturbance, such as atrial fibrillation or rapid rates from an abnormal origin, and will usually be performed if the fibrillation has been picked up early enough. The machine used is a defibrillator.
Under a brief general anaesthetic, an electric current is passed via a paddle on the top of your chest to a paddle on the left side or back (see Figure 6.2). It takes less than five minutes. The abnormal palpitation is halted at its source, and this allows the normal electrics to take over. It is successful 9 out of 10 times. Usually the patient receives warfarin for at least 4 weeks beforehand and a month afterwards to prevent the formation and dislodging of clots. If cardioversion is performed at short notice, your blood is thinned with heparin given through a vein. Cardioversion is usually done as a day-case procedure (in and out the same day) and you will notice how much better your heart behaves almost immediately.
There is no need to worry about electric shock treatment; it is safe and effective provided that all the precautions are taken – making sure of the diagnosis and use of warfarin.
A new technique involving a shock inside the heart is being used more frequently, as it appears to be more successful. A special tube is passed to the heart via the vein at the top of the leg under local anaesthetic. Once it is in place under heavy sedation or a brief general anaesthetic, a shock is delivered almost directly to the atrium, where the problem arises. The results are very encouraging, and you may be offered this as an alternative to the external shock treatment.
My cardiologist has mentioned cardiac ablation. What will this involve? Is it safe?
First, an electrophysiology study (EPS) is performed by a cardiologist in hospital (see the section Tests above). Once the source of the palpitation has been identified, and if the cardiologist considers you to be a suitable case, a special electrical pacemaker catheter can be placed at the source of the palpitations and radio frequency waves used to ablate them (doctors often say ‘zap’!). When the cardiologist is satisfied that all is well,all catheters are removed;pressure is applied to the vein at the top of the leg for 15 minutes or so, and after two to four hours’ bed rest, you will be allowed up and about; you will usually go home the next day. An ECG will be taken to check the rhythm and a 24-hour ECG may be organised to judge the effectiveness of the procedure when you are out of hospital.
Cardiac ablationcan be a lengthy procedure as the catheter has to be placed very accurately. It is usually successful and abolishes the palpitations, removing or reducing the need for medication. Very rarely, the normal electrics are damaged because the abnormal electrics are very close by and they can get caught by the ablation and a pacemaker is then needed.
The procedure can remove young people from a lifetime of dependence on medication; women can become pregnant without fear of any medication damaging the baby. Also, if medication is successful but gives side effects, cardiac ablation is an effective alternative. Because ablation is a very individual procedure, it is important to discuss fully with your cardiologist the potential risks and the chances of benefit for you – not someone in general, but you specifically.
Reference:
1) http://www.PubMed.com
2) Jackson G. Heart Health, 4th edition, Class Publishing, London. |
