Heart block is a condition where the heart beats irregularly or much more slowly than normal. Sometimes the heart may even stop for up to 20 seconds. It is caused by a delay or disruption of the electrical signals that usually control the heartbeat. A healthy heart in an averagely fit person beats between 60 and 80 times a minute. A heartbeat is when the muscles of the heart contract and push blood around the body. These muscle contractions are controlled by electrical signals that travel between the heart’s upper chambers (the atria) and lower chambers (the ventricles).

If these electrical impulses are delayed or sometimes stopped (partial heart block), then the heart may not beat regularly. If the electrical signals are stopped completely (complete heart block), then the heart will only beat around 40 times a minute.

Heart block reduces the heart’s efficiency in pushing blood around the body. This means that the muscles and brain may not be getting enough oxygen for them to work properly.

Symptoms

The main symptoms of heart block are a slow or irregular heartbeat. Symptoms can also include:

• shortness of breath
• palpitations (when you notice the irregular heartbeat)
• fainting or light-headedness
• discomfort or pain in the chest.

Heart block usually happens to older people with a history of heart disease or smoking.

If left untreated, heart block can lead to a stroke and heart failure

Causes

Heart block is caused by damage to the tissue that passes the electrical signals through the heart. This usually happens to older people who have had a heart disease such as:

• cardiomyopathy (disease of heart muscle)
• Coronary thrombosis (sudden blockage in the heart blood vessels)
• myocarditis (inflammation of the muscle in the wall of the heart)
• valvular heart disease (disease of the heart valves).

Sudden complete heart block (either temporary or permanent) can also happen after a heart operation or following a heart attack.

Heart block may also be caused by problems that have been there from birth (congenital heart block).

Treatment

The long-term treatment for heart block is to fit a ‘pacemaker’. This is a small, battery-driven device that sends out electrical signals to keep the heartbeat regular. Modern pacemakers are very sophisticated and some can be set to produce an electrical impulse only when one is needed. Some can even tell when the heart stops beating and produce a small electric shock to restart it. (Older pacemakers used to produce the electrical signal at a constant rate and this limited the patient’s physical activity.)

Before having a permanent pacemaker, some patients might need a temporary ‘pacing wire’. The pacing wire does a similar job to a pacemaker (sending electrical signals to regulate the heartbeat) but is inserted through a vein in the chest or groin area.

Sometimes no treatment is recommended. This may be when patients are elderly and the symptoms are very minor, or where people have other medical conditions that would make the operation to fit a pacemaker too dangerous.