Heart Block

Introduction

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 control the heartbeat.

A healthy heart beats between 60-80 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 imlegumes are delayed or stopped (partial heart block), then your 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 your heart 's efficiency in pushing blood around the body. This means that your muscles and brain may not be getting enough oxygen for them to work properly.

Types of heart block

There are three different types of heart block:

• First degree heart block (the least serious) usually refers to skipped beats, or some other kind of disruption, and often does not need treatment.
  
• Second degree heart block is where some of the electrical signals do not reach your heart , causing 'drooped' beats. It can cause dizziness and sometimes a pacemaker is needed.
  
• Third degree or complete heart block (the most serious) is when the electrical signals do not travel between the upper and lower chambers of your heart . It is most common in adults with heart disease , and can have serious complications, such as heart attack , if it is not treated with a pacemaker.

Bundle branch block/AV bundle

Heart block is also known as bundle branch block or AV bundle . This is because the electrical imlegumes that control the heart 's muscle contraction pass through what is known as the 'bundle of HIS'.

This is the part of your heart where muscle fibers are divided into a right bundle and a left bundle. Together they control the heart 's contraction and, in a normal healthy heart , both contract together.

Bundle branch block is a common condition and, in most cases, there is no obvious cause. If a signal block occurs in the right side of your heart (right bundle branch block) it is not considered a serious concern. However, if the block is in the left side (left bundle branch block) it is usually associated with an increased risk of developing a heart problem, such as coronary artery disease

Causes

Heart block is caused by damage to the tissues that pass electrical signals through your heart (right and left bundle branches). This usually occurs in older people who have had a heart disease such as:

• cardiomyopathy ( disease of the heart muscle),
• coronary thrombosis (sudden blockage in your heart 's blood vessels ),
• myocarditis ( inflammation of the muscle in the wall of the heart ), or
• 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 since 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 your 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 produces a small electric shock to restart it. (Older pacemakers used to produce the electrical signal at a constant rate and this limited a patient's physical activity.)

Pacemakers are not affected by household appliances or any mobile technology, such as mobile phones, or personal stereos. However, a magnetic resonance imaging ( MRI ) scan should not be performed as it may interfere with a person's pacemaker.

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

Sometimes no treatment is recommended for heart block. This may be the case when people 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.