Angina is caused by narrowing and hardening of the main blood vessels going to the heart, which limits blood supply to this major organ.
Like all of the body’s organs and tissues, your heart needs a constant supply of oxygen-rich blood to function normally.
Blood is supplied to the heart by two large blood vessels known as the coronary arteries. Over time, the walls of these arteries can become furred up with fatty deposits. This process is known as atherosclerosis and the fatty deposits are called atheroma.
Coronary heart disease is the term that describes what happens when your heart's blood supply is blocked or interrupted by this build-up of fatty substances.
When you're resting, the muscles of your heart only need a relatively small supply of blood. However, when you exercise or feel stressed, your heart muscles have to work harder and the demand for blood increases. If the coronary arteries are narrowed, the required amount of blood is unable to reach the heart in time, triggering the symptoms of angina.
Anything that causes the coronary arteries to narrow can increase your risk of angina. This can include:
These risk factors can often be inter-related. They're explained below in more detail.
High blood pressure
Your arteries are designed to pump blood at a certain pressure. If that pressure is exceeded, the artery walls may become damaged. High blood pressure can be caused by:
- being overweight
- drinking excessive amounts of alcohol
- a lack of exercise
For reasons that aren't fully understood, high blood pressure is more common among people of Afro-Caribbean and south Asian (Indian, Pakistani and Bangladeshi) origin. A tendency to develop high blood pressure also often runs in families.
Read more about preventing high blood pressure.
High-fat diet and cholesterol
Cholesterol is a type of fat that's essential for the functioning of the body. It helps to produce hormones, protects nerve endings and makes up cell membranes (the walls that protect individual cells). There are two main types of cholesterol:
- low-density lipoprotein (LDL) – mostly made up of fat, plus a small amount of protein; this type of cholesterol can block your arteries, so is often referred to as "bad cholesterol"
- high-density lipoprotein (HDL) – mostly made up of protein, plus a small amount of fat; this type of cholesterol can help to reduce a blockage in your arteries, so is often referred to as "good cholesterol"
Most of the cholesterol the body needs is manufactured by the liver. However, eating foods high in saturated fat increases the levels of bad cholesterol in your blood.
Read more about lowering your cholesterol.
Lack of exercise
A lack of regular exercise can raise your blood pressure and increase your risk of developing type 2 diabetes. Both of these increase your risk of developing angina.
Smoking can damage the walls of your arteries. If your arteries are damaged by smoking, blood cells called platelets form at the site of the damage in an attempt to repair it. This can cause your arteries to narrow.
Smoking also decreases your blood's ability to carry oxygen around your body, which increases the chances of a blood clot occurring.
Read more about stopping smoking.
If you have poorly controlled diabetes, the excess glucose in your blood can damage the walls of your arteries.
As you get older, your risk of developing angina increases, as your arteries are more likely to have narrowed over time.
Heart disease can run in families, so if you have a first-degree relative (mother, father, brother or sister) with a history of heart disease or angina, your risk of developing angina is increased.