Heart attack

What is a heart attack?

The heart beats on average 70 times a minute to push blood around the body. Like any busy muscle, the heart tissues need a good supply of blood from their blood vessels, which are called the coronary arteries. When this process is interrupted or doesn't work properly, serious illness and even death can result.

A heart attack occurs when blood flow to part of the heart is blocked, often by a blood clot, causing damage to the affected muscle. The clot, often caused by rupturing or tearing of plaque in an artery, is sometimes called a coronary thrombosis or a coronary occlusion.

If blood supply is cut off for a long time, the muscle cells are irreversibly damaged and die, leading to disability or death depending on the extent of the damage.

Diseases that narrow the coronary arteries can reduce the supply of blood and cause a shortage of oxygen and essential nutrients in the heart muscle. This triggers chest pain known as angina, especially when the heart is made to work extra hard, for example during exercise. If someone has angina, the more severe the narrowing of the arteries, the less they can do before they experience pain.

A heart attack can occur if the shortage of oxygen to an area of heart muscle is severe and prolonged. Heart attacks (also known as a myocardial infarction or MI) can also occur when a coronary artery temporarily contracts or goes into spasm, decreasing or cutting the flow of blood to the heart.

Most of the deaths from heart attack are sudden, occurring within one hour of onset of symptoms and before reaching hospital, and are often due to dangerous heart rhythms. Most people who survive the first month will still be alive five years later, but many are left with long-term heart problems.

Heart attack symptoms

Unfortunately, for many people the first indication that something's wrong is a heart attack. This happens when the blood supply to a part of the heart muscle is completely interrupted or stops, usually when a blood clot forms in a diseased coronary artery that's already become narrowed by atherosclerosis.

The symptoms of a heart attack include:

• Chest pain, usually a central crushing pain that may travel into the left arm or up into the neck or jaw, and persists for more than a few minutes. Unlike angina, the pain doesn't subside when you rest. Sometimes it can be mild and be mistaken for indigestion. Some people have a heart attack without experiencing pain
• Stomach or abdominal pain
• Shortness of breath or difficulty breathing
• Nausea or vomiting
• Sweating
• Unexplained anxiety
• Weakness or fatigue
• Cold sweat or paleness
• Feeling light-headed or dizzy
• Palpitations or an abnormal heart rate

Heart attacks must be recognised and treated as quickly as possible because once a coronary artery is blocked, the heart muscle will die within four to six hours.

If you suspect you or someone else is having a heart attack, seek medical help immediately by calling 999. Modern treatments can restore the blood supply to the heart muscle. The sooner treatment is given, the less permanent damage there will be.

Causes of a heart attack

The UK has one of the worst heart attack rates in the world. It's estimated that someone has a heart attack every two minutes in the UK. More than 1.4 million people have angina and each year about 275,000 people have a heart attack. Of these, more than 120,000 are fatal.

Common causes include:

• Atherosclerosis, where fatty plaques build up on the inner lining of the coronary arteries (often compared to the furring up you see inside a kettle)
• Smoking
• High cholesterol
• High blood pressure
• Diabetes
• Family history of heart disease

Men are also more likely to have a heart attack than women.

There are many steps you can take to change your lifestyle and reduce your risk, including quitting smoking, eating healthily and keeping your weight under control, and getting regular exercise.