Blood clot blocking an artery (arterial thrombosis)

Symptoms and risks of arterial thrombosis 

A blood clot doesn't usually have any symptoms until it blocks the flow of blood to part of the body.

This can cause several serious problems, including:

• a heart attack – when blood flow to the heart muscle is suddenly blocked, causing chest pain, shortness of breath and dizziness
• a stroke – when blood flow to the brain is cut off; common symptoms include face dropping on one side, weakness in one arm and slurred speech, but it depends upon which part of the brain is affected, and how large a part of the brain is affected
• a transient ischaemic attack (TIA) or "mini-stroke" – when blood flow to the brain is temporarily blocked, causing short-lived stroke symptoms
• critical limb ischaemia – when the blood supply to a limb is blocked, causing it to become painful, discoloured (either pale or blue) and cold

These conditions are all medical emergencies.

Get medical help straight away if you or someone in your care is experiencing these symptoms.

Phone 999 for an ambulance.

Causes of arterial thrombosis 

Arterial thrombosis usually affects people whose arteries are clogged with fatty deposits. This is known as atherosclerosis.

These deposits cause the arteries to harden and narrow over time. This increases the risk of blood clots forming and blocking an artery.

The following can increase your risk of developing atherosclerosis:

• getting older
• smoking
• an unhealthy diet
• lack of exercise
• being overweight or obese
• regularly drinking too much alcohol
• other conditions, including high blood pressure, high cholesterol and diabetes
• a family history of atherosclerosis
• being of south Asian, African or African-Caribbean descent

Sometimes arterial thrombosis can be due to a condition that makes your blood more likely to clot, such as:

• atrial fibrillation
• antiphospholipid syndrome

Reduce your risk of arterial thrombosis 

It's not possible to prevent blood clots entirely. You can help reduce your risk by lowering your risk of atherosclerosis.

The main things you can do are:

• stop smoking 
• have a healthy diet
• exercise regularly
• maintain a healthy weight
• drink less alcohol

If you're at a high risk of getting a blood clot, your doctor may also recommend taking medication such as:

• statins for high cholesterol
• medicines for high blood pressure
• medicines to reduce the risk of your blood clotting – for example, anticoagulants (such as warfarin) and antiplatelets (such as low-dose aspirin or clopidogrel)

Treatments for arterial thrombosis 

If you develop arterial thrombosis, it may need to be treated with medication or surgery. Your doctor or specialist will discuss treatment options with you.

Treatments include:

• injections of a medicine that can dissolve blood clots
• an operation to remove the clot
• an operation to widen the affected artery – for example, an angioplasty (where a hollow tube is placed in the artery to hold it open)
• surgery to divert blood around the blocked artery – for example, a coronary artery bypass graft (where a blood vessel taken from another part of the body is used to bypass a blockage in the artery that supplies the heart muscle)

Other types of blood clot 

As well as arterial thrombosis, there are other types of blood clot, including:

• deep vein thrombosis (DVT) – a blood clot in one of the deep veins in the body, usually in the leg
• if the clot dislodges it can travel to another part of the body causing another block in the circulation (thromboembolism)
• if the dislodged clot ends up in the pulmonary artery (which transports blood from the heart to the lungs) it causes a pulmonary embolism 
• embolism -  describes when the blood flow in an artery is blocked by a foreign body; this can be a blood clot or something else such as an air bubble

More useful links

• How to use your health services