Peripheral arterial disease - Causes of peripheral arterial disease

Peripheral arterial disease (PAD) is usually caused by a build-up of fatty deposits on the walls of the arteries inside the legs. The fatty deposits, called atheroma, are made up of cholesterol and other waste substances.

The build-up of atheroma on the walls of the arteries makes the arteries narrower and restricts the flow of blood to the legs. This process is called atherosclerosis.

People with PAD can experience painful aching in their leg muscles during physical activity, because the muscles are not receiving the blood supply they need.

Like all tissue in your body, muscles in your legs need a constant supply of blood to function properly. When you are using your leg muscles, the demand for blood increases significantly. But if the arteries in your legs are blocked, the supply of available blood cannot meet the demand.

This shortfall between supply and demand causes your muscles to experience painful aches, which usually get better when you rest your legs.

Increased risk

There are some risk factors for PAD that cannot be changed, such as a family history of heart disease and atherosclerosis, or your age.

As you get older, your arteries naturally begin to harden and get narrower, which can lead to atherosclerosis and then PAD.

However, there are many things that can dangerously speed up this process, which are described below.

Smoking

Smoking is the single most important factor that increases your risk of PAD. Smoking can damage the walls of your arteries. Tiny blood cells, known as platelets, will then form at the site of the damage to try to repair it, which can cause your arteries to narrow.

It is estimated that more than 9 out of every 10 people who develop PAD smoke or have done so in the past.

Diabetes

If you have poorly controlled type 1 diabetes or type 2 diabetes, the excess glucose in your blood can damage your arteries and increase your risk of developing PAD. Around 2 out of every 10 people with PAD has diabetes.

People who have poorly controlled diabetes and PAD are also more likely to eventually need an amputation as a result of severely restricted blood flow to the legs.

High cholesterol

Cholesterol is a type of fat that is essential for the body to function.

There are two main types of cholesterol:

• Low-density lipoprotein (LDL) is the main cholesterol transporter, and carries cholesterol from your liver to cells that need it. If there is too much cholesterol for the cells to use, this can cause a harmful build-up in your blood and lead to atherosclerosis. For this reason, LDL cholesterol is sometimes called "bad cholesterol".
• High-density lipoprotein (HDL) carries cholesterol away from the cells and back to the liver, where it is either broken down or passed from the body as a waste product. For this reason, it's sometimes called "good cholesterol".

Most of the cholesterol your body needs is made by your liver. However, if you eat foods high in saturated fat, the fat is broken down into LDL, which is then passed into your blood vessels.

Read more about high cholesterol.

High blood pressure

Your arteries are designed to pump blood at a certain pressure, and if blood pressure is too high (known as hypertension), the walls of the arteries can become damaged.

High blood pressure can be caused by:

• being overweight
• drinking excessive amounts of alcohol
• stress
• smoking
• a lack of exercise

Read more about high blood pressure.