About the heart

The heart is a large muscle that pumps blood around your body. The blood delivers oxygen and nutrients around your body and takes away carbon dioxide and waste products.

The heart is divided into 4 chambers – 2 on the right and 2 on the left:

  • The 2 smaller upper chambers collect blood going into the heart. These chambers are called the right atrium and the left atrium.
  • The 2 larger lower chambers pump blood out of the heart. These chambers are called the right ventricle and the left ventricle.

The illustration shows a cross-section of the heart from the front. It shows where tubes (blood vessels) join the heart. Arrows indicate the direction blood flows through these blood vessels, into, through and out of the heart.   Four different chambers are shown inside the heart. The two at the top of the heart are called the right atrium and left atrium. The two lower and larger chambers are called the right ventricle and left ventricle. The arrows show that blood travels into each atrium, then through flaps (called valves) and into each ventricle. The arrows then show that blood leaves the ventricles through another set of valves and away from the heart through another set of blood vessels.

There are 4 valves inside the heart. They open and close as the heart pumps blood. The valves keep the blood flowing in one direction through the heart.

Blood travels around the body through tubes called blood vessels. The blood going to the heart is low in oxygen. It travels through the heart and is pumped out to the lungs.

In the lungs, the blood picks up oxygen and gets rid of carbon dioxide, which is then breathed out. The blood carrying oxygen travels back through the heart and is pumped out to the body again.

The illustration shows the front of the heart and where tubes (blood vessels) join the heart. Arrows indicate the direction blood flows through these blood vessels to enter and leave the heart. Some arrows are red to show blood that has oxygen. Some arrows are blue to show blood that needs oxygen.  Above the heart is labelled upper body. Below the heart is labelled lower body. Either side of the heart is labelled lungs.   Blue arrows (blood that needs oxygen) enter the heart through blood vessels from the upper and lower body. Red arrows (blood that has oxygen) leave the heart through different blood vessels to the upper and lower body.   Blue arrows leave the heart through blood vessels to each lung. Red arrows enter the heart through blood vessels from each lung.  The main body of the heart is labelled heart muscle. A network of thin lines is shown on the surface of the heart muscle. These are called coronary arteries.

Like the rest of your body, the heart needs its own blood supply to bring it oxygen. Small blood vessels on the outside of the heart carry blood and oxygen to the heart muscle. These blood vessels are called coronary arteries (see diagram).

The heart has its own electrical system that tells it when to beat and pump blood around the body. A group of cells called the sinus node send an electrical signal through the heart to start each beat. This happens about 60 to 100 times a minute. The sinus node is also known as the heart’s natural pacemaker.

About heart conditions

When parts of the heart become diseased or damaged, this can cause heart problems. You can read about some of the most common types of heart conditions below. The British Heart Foundation also have information.

We have more information about:

Coronary heart disease (CHD)

Coronary arteries are the small blood vessels that carry blood and oxygen to the heart muscle. Sometimes, fatty deposits (called atheroma) can build up inside the arteries. This can make the arteries narrow and is called coronary heart disease (CHD) or coronary artery disease.

The illustration shows two tubes. These are two blood vessels or arteries. The arteries are shown in cross section. An arrow shows how blood flows through each vessel. In one artery, the arrow is large to show that the blood flows easily along the blood vessel. This is labelled normal blood flow. In the other artery, there is an area of fatty tissue attached to the inside of the artery wall. This makes the inside of the artery much narrower. The arrow becomes small and thin to fit past the fatty tissue. It is labelled abnormal blood flow. 

Certain things, called risk factors can increase the risk of CHD. These include:

  • smoking
  • being overweight
  • high blood pressure
  • a high blood cholesterol level
  • diabetes
  • a lack of exercise
  • age – you are more likely to develop CHD as you get older
  • a family history of CHD
  • some cancer treatments.

The more risk factors you have, the more likely you are to develop CHD.

Symptoms of CHD

Sometimes a blood vessel gets so narrow that it does not let enough blood and oxygen flow to the heart muscle. This can cause symptoms.

The main symptom of CHD is chest pain or discomfort, known as angina. Angina often feels like a heaviness or tightness in your chest. Some people describe a feeling of:

  • a dull ache – a bit like indigestion
  • severe tightness.

The pain and discomfort may spread to your arms, neck, jaw or stomach.

Other symptoms of CHD include:

  • feeling short of breath
  • extreme tiredness (fatigue) on physical exertion.

These symptoms often develop when you are physically active, exercising or stressed. They may also develop after a meal, or in cold weather. Symptoms usually go away when you rest and relax.

Heart attacks

Sometimes a piece of fatty deposit can break off and a blood clot forms. This may block the blood vessel, stopping the flow of blood to parts of the heart. This is called a heart attack. It can cause permanent damage to the heart muscle.

The symptoms of a heart attack vary from person to person. The most common sign is sudden pain or discomfort in your chest that does not go away.

For some people, the pain is severe. Other people just feel uncomfortable. Sometimes the chest pain or discomfort:

  • feels like tightness, heaviness or burning in your chest
  • may spread to the arms, neck, jaw, stomach or back.

You may also:

  • feel sweaty
  • feel dizzy or light-headed
  • be short of breath
  • feel sick or vomit
  • feel generally unwell.

If you think you or someone else is having a heart attack, call 999 immediately for an ambulance.

Heart muscle damage

Damage to the heart muscle can make it harder for the heart to pump blood around the body.

The most common reasons for heart muscle damage are:

  • a heart attack
  • high blood pressure
  • heart muscle disease, which is also called cardiomyopathy
  • problems with the heart valves or rhythm
  • being born with a heart problem (congenital heart disease)
  • some infections
  • using recreational drugs or excessive alcohol
  • some cancer treatments.

Heart failure

Damage to the heart muscle can lead to heart failure. This does not mean that the heart stops. It just means that it does not pump blood around the body as well as usual.

Symptoms of heart failure can include:

  • feeling short of breath, when you are physically active, or at rest
  • feeling unusually tired or weak (fatigue)
  • swollen feet, ankles, legs or tummy (abdomen).

Heart valve disease

The heart valves can become stiff and not open properly. Or they may not close tightly and the blood may leak backwards.

The main causes of heart valve disease are:

  • infection
  • damage to the heart muscle from a heart attack
  • disease of the heart muscle (cardiomyopathy)
  • being born with an abnormal heart valve (congenital heart valve disease)
  • getting older
  • radiotherapy to the heart or nearby areas.

You may not have any symptoms, but the main symptoms of heart valve disease are:

  • feeling unusually tired
  • feeling short of breath
  • swelling of the legs, feet and ankles.

If valve problems are not treated it can put a strain on the heart. This can sometimes lead to heart failure over time.

Electrical heart problems

A problem with the heart’s electrical system may make your heart beat:

  • too fast
  • too slow
  • with an irregular pattern.

This is different to the normal changes in heart rhythm that can happen during the day. For example, your heart may beat slower when you are resting, and faster when you are active or feeling anxious. An abnormal heart rhythm is called an arrhythmia.

There are many reasons why someone may have an abnormal heart rhythm. It is more common in older people or people who already have a heart condition. Some cancer treatments can also affect the electrical system and how the heart beats.

Many people have palpitations from time to time. This is the sensation of feeling your heart beating. It may feel like your heart is:

  • fluttering
  • pounding
  • beating too fast, too slow or irregularly
  • skipping a beat.

For most people palpitations are harmless and do not mean anything is wrong with your heart. But sometimes it can be a sign of a problem.

Symptoms of arrhythmia

Some arrhythmias are more serious than others. The symptoms depend on the type of arrhythmia you have.

The most common symptoms include:

  • palpitations
  • feeling dizzy
  • breathlessness
  • blackouts (fainting).

About this information

Our information about heart health and cancer was developed in partnership with the British Heart Foundation.

If you have questions about your heart health, call the Heart Helpline on 0300 330 3311, Monday to Friday, 9am to 5pm, or visit bhf.org.uk.

Date reviewed

Reviewed: 01 February 2019
Next review: 01 February 2022

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.