A B C D E F G H I J K L M N O P R S T U V W

ATRIAL HEART RHYTHM ABNORMALITIES

What are Atrial Heart Rhythm Abnormalities?

The heart has an electrical system which makes sure that the chambers of the heart beat in a regular manner. Each heartbeat starts with a spark in a tiny area of the heart called the sinus node. The impulse passes through the receiving chambers (the atria), to the pumping chambers (the ventricles) through a conduction system. Although the heart's pumping function may be normal, it will not work properly if there are electrical defects. There may be defects in the sparking or the conduction, and this can cause short circuits with too many electrical impulses. The heart may then beat too fast, or irregularly. What effect this has depends on the speed of the heart, the age of the patient and whether there is other heart disease. An awareness of a rapid rhythm is often called "palpitation" and the rapid rhythm itself is called a tachycardia. Young people can tolerate rapid heart rates (up to 200 beats per minute) if their hearts are otherwise normal. Some may not even be aware of it. Older people feel dizzy and may even faint with a much smaller change in the speed of the heart. In addition, the patient may feel breathless, get chest discomfort or pain, and feel sick or sweaty.

The type of heart rhythm is also important. If the rapid rhythm comes from the receiving chambers (atrial tachycardia), it is usually less important than if it starts in the pumping chambers (ventricular tachycardia). There are different types of abnormal atrial rhythm. The commonest is called atrial fibrillation, in which the rhythm is both rapid and irregular. A slow type of palpitation is caused by extra beats called ectopics or extrasystoles. These beats are weak but are usually followed by a pause which some people feel as a missed beat. The next beat is normal but is strong and can also sometimes be felt as a thump. Unless there is other heart disease present, ectopic beats are unimportant. They do not need treatment. Many people have them without knowing it.

How and why do Atrial Heart Rhythm Abnormalities occur?

Many patients with atrial tachycardias have only an electrical defect without other heart disease. Others may develop the abnormal rhythm because of alcoholism, overactivity of the thyroid gland, disease of the lungs, or because of an abnormality of one of the heart valves. They can also be due to other forms of heart disease such as coronary disease, including heart attacks (myocardial infarction), heart muscle disease (cardiomyopathy), congenital heart disease, or infection. Changes in heart rhythm may occur now and then, the heart switching back and forth from normal to abnormal. These switches may happen very frequently (several times a day) or very seldom (once or twice a year).

What does treatment/management of Atrial Heart Rhythm Abnormalities involve?

DIAGNOSIS

Any underlying abnormalities which are present are treated. For example, treatment is required for a heart attack (myocardial infarction) and for the other diseases mentioned above. Electrocardiograms (ECGs) are used to record the rhythm and to distinguish an atrial tachycardia from a ventricular tachycardia. As the abnormal rhythm may not be present all the time, the ordinary ECG may not help. If the attacks are brought on by exercise, an exercise test may be useful. The ECG is recorded whilst you walk on a treadmill at a gradually increasing speed and incline. A portable 24 hour Walkman- sized ECG (Holter) recorder can be used to record ECG faults which come and go. ECG wires are stuck to the skin of the chest and are connected to the recorder, which is carried on a belt. If this recording is also normal, pocket sized recorders may be carried for several weeks. These are placed on the skin when you have an attack (event ECG) and are switched on by pressing a button. The recording can then be relayed over the telephone. A similar recorder, called a loop ECG can record for several days (as long as the batteries last). It only retains the last 10-20 minutes recording in the memory. After an episode of palpitation this can be ‘frozen’ in the memory by pressing a button. ECGs from inside the heart can be recorded if all the other methods fail to allow a diagnosis. Thin wires (electrodes) which are passed inside the heart from the veins in the groin or neck. This type of investigation is called an electrophysiological study. A special pacemaker can be used to start and stop a tachycardia easily and the effect of various medications can be tested.

TREATMENT

Various medicines are used either to slow the heart or put the rhythm back to normal. Atrial tachycardias are often slowed by digoxin (originally made from the foxglove leaf!), or to beta?blockers which block the effect of adrenaline on the heart. Other drugs frequently used to control atrial tachycardias include verapamil, flecainide and amiodarone. These last two are often used to prevent attacks. A variety of other medications can also be used, including adenosine which is given by injection. If an attack is bad and not stopped by medicines, a short general anaesthetic can be given, followed by an electric shock from a machine called a defibrillator. This usually returns the heart rhythm to normal and is very safe. The condition of atrial fibrillation may cause blood clots to form in the heart. Therefore, blood thinning tablets (anticoagulants) are usually recommended for people over the age of about sixty.

An electrophysiology study can be extended to provide treatment as well as diagnosis. Short bursts of radio-frequency electrical energy can be passed through special electrodes. These heat the tip to 50 – 60º centigrade. This burns out tiny sections of the electrical pathways that are responsible for the short circuits which cause the rapid rhythm. This is called ablation therapy. It has the advantage that it usually leads to a permanent cure. Because ablation therapy is so successful, other techniques such as permanent pacemakers are used less often. They are used mainly for treating slow heart rhythms, but can occasionally be used for treating fast rhythms.

What to watch out for during treatment of Atrial Heart Rhythm Abnormalities?

Medications are more successful in some people than others. If the abnormal rhythm (palpitation) recurs, the doctor must be told. If the drug is not working, another one may be tried. All treatments have side?effects, mostly minor ones. On the whole, with medication, abnormal heart rhythms are controlled rather than cured: once any drug is started, it must be continued and taken regularly to be effective. Any medication can occasionally make the tachycardia worse and others may have to be tried. Ablation therapy is usually curative. However, with some tachycardias there is a very small risk of causing a very slow heart rhythm. This might require a permanent pacemaker. After successful ablation, minor palpitation may still be present but is not usually troublesome or important.

What would happen if Atrial Heart Rhythm Abnormalities were not treated?

Atrial tachycardias are not usually very serious. In fact, if they are not troublesome or frequent, they can sometimes be left untreated. However, treatment may be needed in older people who are more likely to have symptoms. Also, in some people who have a very rapid heart rate (greater than 200 beats per minute), there may be some danger in leaving it untreated. It is always best, therefore, to seek advice about whether it is important or not to have treatment.

What is involved for family & friends?

The presence of a tachycardia in itself should not usually cause concern. If there is an underlying heart condition, this may need separate treatment. This condition may affect lifestyle, in which case some support from the family is always helpful.