Congestive heart failure - Causes of heart failure

In most cases, heart failure does not have a single cause.

There are a number of other conditions that increase your chances of developing heart failure. These include:

• high blood pressure (hypertension) – this can put extra strain on your heart, which can lead to heart failure
• coronary heart disease (CHD) – where the arteries that supply blood to your heart become clogged up by fatty substances (atherosclerosis); this may cause angina or a heart attack
• heart muscle weakness (cardiomyopathy) – this can cause heart failure; the reasons are often unclear, but it may be genetic in origin, or caused by infections (usually viral), alcohol misuse, or medication used to treat cancer
• heart rhythm disturbance (atrial fibrillation)
• anaemia – a lack of red blood cells
• an overactive thyroid gland

There are also a number of other conditions that can increase your risk of developing heart failure. Some of these are discussed below.

Heart rhythm abnormalities (arrhythmias)

If your heart beats too fast, it may not have enough time to fill and empty properly. This will cause the heart muscle to weaken.

A very slow heartbeat (less than 40 beats per minute) may reduce the output of your heart, leading to the symptoms of heart failure. However, some people who are very fit can have a pulse of less than 40 beats per minute.

An irregular heart rhythm (atrial fibrillation is the most common irregularity) increases your risk of developing a blood clot (thrombosis), which may cause a stroke. In some people, it may also cause heart failure, particularly if the heart rate is too fast.

Damaged heart valves

The heart contains four one-way valves that ensure the blood flows in the right direction. A leaking valve means your heart has to work harder and will stretch to deal with the extra volume of blood.

A narrowed valve can obstruct blood flow and reduce the amount of blood that your heart can pump, as well as increase the stress on the heart muscle.

Some children are born with faulty valves (congenital heart disease). Heart valves can also be damaged during a heart attack, or sometimes they can just wear out. The average heart beats about 75 times per minute, which is 4,500 beats an hour or more than 100,000 heart beats a day.

Some damaged heart valves can be repaired, but others have to be replaced. This usually requires an open heart operation, although less invasive alternatives are now becoming available and can be used in certain situations.

Myocarditis

Myocarditis is inflammation of the heart muscle. It is usually caused by a viral infection and can sometimes lead to heart failure. However, myocarditis is rarely recognised as a cause of heart failure in the UK.

Other congenital heart conditions

Some babies are born with a "hole in the heart", which is an abnormal connection between the left and right sides of the heart.

This allows blood to flow from one side of the heart to the other (usually left to right), putting a strain on the right side and sometimes causing heart failure.

In some cases, a hole in the heart may not be detected until adult life. Holes can often be plugged using keyhole surgery techniques, though sometimes an operation is required.