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

DISEASE OF THE HEART'S CONDUCTING SYSTEM

What is a Disease of the Heart's Conducting System ?

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, the sinus node. It is transmitted to the pumping chambers (ventricles) by an electrical conducting system. Although the heart's pumping function may be normal, it win not work properly if there are electrical defects. Defects occur in the sparking (sinus node disease) or the transmission of the impulse (conduction disease). The heart may even stop beating for short periods, causing blackouts. Symptoms vary; some people feel dizzy or fall without passing out. Some people may have defects without symptoms. Pacemakers provide an artificial electrical system to correct these defects.

Why does a Disease of the Heart's Conducting System occur ?

In about half the patients with an abnormal electrical system, no other heart disease can be identified. Of the remainder, most have coronary artery disease. In some it is a complication of a heart attack (myocardial infarction). In this case, it usually gets better of its own accord, although some people do need a pacemaker temporarily. There are a few rarer causes, such as auto?immune disease, aortic valve disease, or heart muscle disease (cardiomyopathy).

Treatment Involved for a Disease of the Heart's Conducting System

DIAGNOSIS An electrocardiogram (an electrical recording of the heart rhythm) usually makes the diagnosis and shows the type of electrical defect. Sometimes, the electrocardiogram (ECG) can be normal. It may also be difficult because the symptoms are vague or not very frequent; dizziness in elderly people is common and often due to other causes. When the ordinary ECG does not help, portable 24 hour Walkman-sized ECGs (Holter recorders) can be used. These record ECG faults which only occur over rather shorter periods – and could therefore be missed on a “one-off” ECG recording. If such a Holter recording is also normal, pocket sized loop or event recorders are used. These can be activated by the patient if he or she notices any palpitations or other symptoms. They may be carried for several weeks. ECGs from wires inserted inside the heart (electrophysiology studies) can be recorded if all the other diagnostic methods fail. TREATMENT There are no pills or medicines which can safely be used for these problems. The only treatment is a pacemaker which provides artificial electrical sparks (impulses) in place of natural ones. Temporary pacemakers are used when the disease is expected to improve by itself (as usually happens after a heart attack). They are also used as a standby, as initial treatment when a permanent pacemaker will be needed. A thin wire (electrode), is threaded into the heart from a vein in the shoulder or neck, using a little local anaesthetic. It is carefully positioned in the heart using x?rays. The other end of the wire is attached to the small pacemaker box which can be carried by the patient. For permanent pacing, one or two electrodes are inserted in a similar way, also with local anaesthetic. This is done with special care as they must last a long time. Permanent pacemakers are about 4cm (under 2 inches) in diameter and less than 1 cm (½ inch) thick. They are connected to the electrode and placed under the skin usually just below the collar bone. This is done through a small incision under local anaesthetic. They contain batteries which last between 5 and 12 years. They also contain the electronic circuits, all in one package. One circuit switches off the pacemaker if the natural heart rhythm is faster than the pacemaker. Some pacemakers have two electrodes and mimic the natural heart rhythm. They follow the natural sparking mechanism if it functions normally, speeding up with exercise and slowing with rest. Other pacemakers mimic this "rate response" even when the natural sparking is defective. Pacemakers which speed up in this way are especially helpful for heart failure symptoms (breathlessness and ankle swelling) and for people who are very active physically. Care is taken by the doctors to avoid infection in the wound, since it is almost impossible to eliminate with antibiotics, and the pacemaker has to be removed. The infection then disappears and a new pacemaker can be implanted.

After Treatment for a Disease of the Heart's Conducting System

You should take care with the wound for about 10 days. If there is any sign of infection, such as redness, soreness, weeping or swelling this should be notified to the doctor immediately Until healing is complete, you should not put stress on the wound unduly. After about a month it is permissible to exercise normally in every way (including driving and sexual activity) and forget about the pacemaker. The pacemaker should be checked by a specialist in a special clinic. This will be done several times in the early months and then just once a year. Modern pacemakers are reliable and rarely go wrong but the clinics are designed to pick up faults before you do! Very occasionally there can be a fault with the electrodes. If there is any suspicion of previous symptoms, such as dizziness or blackouts, the doctor should be told. When the batteries start to run down, checks will be more frequent. The pacemaker will be changed long before any trouble is likely to occur from run?down batteries. Modern pacemakers are protected from outside electrical interference. Theoretically, microwaves, diathermy (as used in some physiotherapy departments), and high?energy electrical fields can affect them. In practice this rarely happens. Microwave ovens should not emit microwaves unless they are faulty. Electronic sensors, as in airports, are metal detectors. Although they will alarm, they will not usually interfere with pacemaker function. Mobile telephones can theoretically interfere: in practice this is very unusual. The ‘phone should be held on the opposite side of the body. Try and forget about your pacemaker - but carry the card that you will be given with details about you, your pacemaker, your hospital and your doctor!

If a Disease of the Heart's Conducting System is Left Untreated

With conduction defects, treatment is usually important because the disease may otherwise be life?threatening. This is true even when there are no symptoms. In sinus node disease, there is no such threat and pacemakers are usually used only when there are symptoms.

Effects on Family of a Disease of the Heart's Conducting System

You should be able to return to a completely normal life and it should not affect your family or friends at all. They can forget that you have a pacemaker, just as you can!