Peripheral artery disease (PAD)

Arteries and blood vessels in other parts of your body can become blocked with plaque (fatty deposits), too. Peripheral artery disease (PAD) occurs when plaque clogs the arteries in your legs. This reduces blood flow to your legs and feet.

The lack of blood flow can cause leg or hip pain. You may notice cramping, pain or tiredness in your leg or hip muscle when you walk or exercise. The feelings go away when you rest but return when you resume activity. PAD usually does not have symptoms until the blockage causes leg pain.

As arteries become blocked, smaller blood vessels carry the blood around the blockage. These vessels are known as collateral blood vessels.

What happens with PAD

In an artery free of plaque (fatty deposits), blood flows freely.	When plaque starts choking an artery, blood cannot flow freely, leading to peripheral artery disease (PAD).	When an artery becomes blocked, smaller blood vessels around the blockage carry the blood. Those smaller vessels are known as collateral blood vessels.

A thrombus occurs when blood cells attach to plaque.

An embolus is a blood clot that breaks away from the thrombus and travels through the bloodstream.

How a thrombus and an embolus form

Blood cells that attach to the plaque can form a blood clot, known as a thrombus. If the thrombus is not treated, a small blood clot may break away and float through the bloodstream.

The clot, known as an embolus, travels through the bloodstream until it becomes stuck in a blood vessel (see below, left). When the clot becomes stuck, the vessel is blocked and blood cannot pass through well, or even at all. This can cause permanent damage to the affected leg.