Heart Diseases- IV-Stroke - ischaemic-BBC.

Stroke caused by blood clots or other obstructions – ischaemic stroke – accounts for 80% of all cases.

A blockage is called a cerebral thrombus or cerebral embolism and can be caused by atherosclerosis – hardening of the arteries.

In both types of stroke – those caused by blood clots and those caused by burst blood vessels – blood supply to the brain is interrupted, depriving the cells of oxygen and other nutrients. The cells are then damaged or die.

Mini-strokes, or transient ischaemic attacks (TIAs), may be a warning sign of an imminent full-blown stroke.

Embolic

In an embolic stroke, a blood clot – or embolus – forms somewhere in the body, usually the heart, and travels through the bloodstream to the brain.

Once in the brain, the clot eventually travels to a blood vessel small enough to block its passage. The clot lodges there, blocking the blood vessel and causing a stroke.

Thrombotic

In the other form of blood-clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain – a thrombus.

The process leading to this blockage is known as thrombosis and strokes caused in this way are called thrombotic strokes.

In atrial fibrillation, where the two upper chambers of the heart – the atria – quiver instead of beating properly, blood is not properly pumped out of the heart. As a result it may form clots and if the clot becomes lodged in an artery in the brain, a stroke may result.

The American Heart Association says arond 15% of strokes are caused in this way.

Blood clot strokes can also happen as the result of unhealthy blood vessels clogged with a build up of fatty deposits and cholesterol.

The body regards these build ups as multiple, tiny and repeated injuries to the blood vessel wall and reacts as it would to bleeding from a wound, by forming clots.

The symptoms of stroke:

Sudden numbness or weakness of the face, arm or leg, particularly if it is on one side of the body

Sudden confusion, trouble speaking or understanding. Sudden difficulty with walking, dizziness, loss of balance or co-ordination

Sudden trouble seeing in one or both eyes

Sudden severe headache with no known cause

Anyone identifying themselves or friends or family as having a stroke should call emergency services, not a GP, as any delay reduces the chance of a full recovery.

The speed of treatment after a stroke is extremely important as the longer the brain cells are deprived of oxygen, the more damage they will suffer.

Treatment

Clot-busting drugs can be used in the first minutes or hours – up to a maximum of three hours – after an ischaemic stroke to dissolve the clot.

After this time aspirin, which is not as powerful, may be given.

Survival rates are better for patients in specialist stroke units, because of the expert nature of staff and early use of rehabilitation, but such units are not always available.

Rehabilitation programmes will be given to most stroke patients to help them recover lost mobility and speech.

http://news.bbc.co.uk/2/hi/health/medical_notes/g-i/764070.stm

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