What is ischaemic stroke?

There are two main types of stroke: ischaemic stroke and hemorrhagic stroke. Ischaemic strokes account for about 80% of all stroke cases. An ischaemic stroke occurs when an artery supplying oxygen-rich blood into the brain is blocked and oxygen cannot reach the brain tissue.

This page details the types of ischaemic stroke and the treatment given. For more information on stroke signs and symptoms, diagnosis, complications and rehabilitation, see our stroke report.


There are two main types of ischaemic stroke: thrombotic stroke and embolic stroke. A transient ischaemic attack (TIA) is not a stroke proper, but a temporary neurological episode.

Thrombotic stroke

A thrombotic stroke is caused by a blood clot that forms within an artery in the brain. It arises from fatty deposits (plaques) that build up inside the artery, a condition known as atherosclerosis. These plaques can rupture, which creates a surface for a blood clot to form. This clot can completely block the artery.

Large arteries of the brain, which are the main blood supply to the brain, are more likely to be blocked by thrombotic strokes than embolic strokes. This is why a thrombotic stroke is most likely to have larger-scale effects.

Thrombotic strokes account for more than half of all strokes.

Embolic stroke

An embolic stroke is caused by a blood clot that travels from elsewhere in the body and lodges in an artery in the brain. The blood clot (embolus) that causes the stroke is commonly the result of existing heart problems, such as atrial fibrillation or aortic stenosis (the abnormal narrowing of the aortic valve).

Thrombotic stroke and embolic stroke are the two types of Ischaemic stroke.Types of Ischaemic stroke. 

Transient ischaemic attack

A transient ischaemic attack (TIA), also known as a 'mini-stroke', is caused by a temporary blockage or narrowing in a blood vessel leading to the brain. A person experiencing TIA will have signs and symptoms like those of a stroke, but will recover within minutes or a few hours.

It is important to note that a TIA is a warning sign. TIAs occur when the blood vessels feeding the brain are not in good condition; a person who has had a TIA is at risk of stroke, often within days of the TIA.

For more information on TIAs, see our transient ischaemic attack report.


A blood vessel carrying blood saturated with oxygen from the heart to the body's tissues.


Of the nervous system, including the brain.


The thickened or solid mass formed from a liquid, such as blood. Blood clots normally form at an injury site to prevent further blood loss.

Aortic stenosis

An abnormal narrowing of the aortic valve, the heart valve that controls blood flow out of the left ventricle.

Types of treatment

Stroke is a medical emergency, and should be treated at a hospital. The immediate concern during an ischaemic stroke is to restore normal blood flow to the brain by dissolving the blood clot.  


Once an ischaemic stroke is diagnosed, medicines are injected into the bloodstream that will dissolve the blood clot, prevent it from growing bigger and prevent other clots forming. These include:

  • Tissue plasminogen activator (tPA), a substance that dissolves blood clots, [1] currently the best treatment for ischaemic stroke;
  • Anticoagulants, which prevent further blood clots from forming. They are also known as 'blood thinners', and;
  • Aspirin, which prevents further blood clotting.

Meanwhile, treatment of ischaemic stroke must also focus on stabilizing the patient's condition - mainly taking care of their blood pressure and their breathing status.


In some cases, a blood clot can also be removed surgically - by carotid endarterectomy or cerebral angioplasty.

Carotid endarterectomy.

Carotid arteries are the two main arteries in the neck that supply the brain with blood. If they are clogged, carotid endarterectomy can be tried. An incision is made in the neck and the internal lining of the artery that contains the plaque is removed.

Cerebral angioplasty

Cerebral angioplasty is also known as stenting. Angiography is used to direct a thin catheter to the blood clot, where a collapsible wire basket is used to then extract the blood clot. A balloon is then used to dilate the blood vessel, before a small cylinder, called a stent, is left in the blood vessel to keep blood flowing to the brain.


After the cause of stroke has been successfully treated, the rehabilitation stage can begin. Its general goals are to restore the person to normal function if possible and to prevent complications. The character, length, intensity and outcome of this stage are different for every person.

For more information on stroke rehabilitation, see our stroke page.


A blood vessel carrying blood saturated with oxygen from the heart to the body's tissues.


A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.


The thickened or solid mass formed from a liquid, such as blood. Blood clots normally form at an injury site to prevent further blood loss.


A imaging test that allows accurate visualization of blood vessels, and any related blockages, within the body. It is an invasive procedure that uses injection of dye into blood vessels, followed by X-ray imaging to detect the dye.

1. Broderick, J.P., Palesch, Y.Y., Demchuk, A.M., et al. (2013). Endovascular Therapy after Intravenous t-PA versus t-PA Alone for Stroke. New England Journal of Medicine 368: 893–903.