High blood pressure and stroke

Lesley Dobson / 05 April 2017

Why is high blood pressure linked to strokes and what can you do to reduce your risk of a stroke?



What is a stroke?

A stroke is rather like a heart attack, because the damage happens when a blood clot blocks blood travelling along an artery (or vein). The difference is that the blockage – the trigger for a stroke - happens in your brain rather than your heart.

‘High blood pressure causes damage to the artery walls, and these lead to the brain as well as the heart and elsewhere in the body. When a blood clot blocks an artery in your heart, it causes a heart attack. When a blood clot blocks an artery in your brain, and stops the blood supply, it causes a stroke,’ says Julie Ward, senior cardiac nurse at the British Heart Foundation.

High blood pressure – particularly uncontrolled high blood pressure – is one of the main causes behind the incidence of stroke in the UK. This is because high blood pressure can damage the blood vessels in your brain, and make them narrower. This can make it more difficult for blood to get through, and makes it more likely that a blood vessel might become blocked, or might even burst.

If this happens, it means that oxygen and energy-carrying blood may not be able to reach parts of the brain. Eventually, the brain cells that have been starved of oxygen can die. When this happens, you have had a stroke.

The effects that a stroke has on your brain and body are governed by the location of the blood clot, and its severity.

Some blood clots cause strokes that may not cause too much damage – for instance a stroke may only affect one of your hands.

At the other end of the scale some strokes can be so severe that they may leave you partially paralysed.

If the stroke is severe, and medical help isn’t available quickly enough, a stroke can cause death. 

Stroke: signs, symptoms and risk factors

Types of stroke

Transient ischaemic attack (TIA) or ‘mini-stroke’

There are a number of different types of stroke. The type that is likely to be least damaging is a transient ischaemic attack or TIA. You may also hear this referred to as a mini-stroke.

A TIA is similar to a stroke, however the blockage of the supply of blood to your brain doesn’t last for long. This means that its effects are only temporary and at most, usually last for 24 hours.

However, this doesn’t mean that you can ignore a TIA. Although the effects may have passed, it could be a sign of problems such as narrowing of your arteries caused by fatty deposits. This could lead to further problems that could be far worse.

The advice from the Stroke Association is that anyone who has had a TIA is at an increased risk of stroke, and should be treated urgently.

Mini-stroke: recognising the signs and symptoms

Ischaemic stroke

An ischaemic stroke happens when a blood clot develops in one of your arteries and then travels to your brain, where it blocks an artery.

This can happen if you have atherosclerosis, a condition that happens when the walls of your arteries harden and become furred up with fatty material known as atheroma. Thick areas of atheroma can trigger blood clots to form, which are carried along in the blood stream. If the blood clot blocks an artery in your heart, this can cause a heart attack.

If the blood clot happens in an artery leading to your brain, it can cause a blockage in the brain, this is known as an ischaemic stroke.

Ischaemic strokes are the most common – about one in ten strokes are haemorrhagic.

Read more about atherosclerosis and blood pressure

Haemorrhagic stroke

Haemorrhagic strokes are caused when, instead of an artery in your brain being blocked, it becomes weakened, bursts, and causes bleeding in your brain, which affects the brain tissue in the area. The term for this is intracerebral haemorrhage, and it can mean that the cells in the area may be damaged or may die.

Signs of stroke

While the specific symptoms of a stroke can vary from one person to another, depending on which part of the brain has been affected, it can be difficult to remember them all.

These are some of the symptoms that you may experience.

  • Feeling unsteady, or dizzy
  • Difficulties with balancing and co-ordination, as well as with speech, eyesight and the ability to smile – their face may also look twisted, and they may be drooling.
  • They may have a headache and may be confused.
  • In more severe cases the person may become unconscious.

If you are concerned that you won’t be able to recall all these symptoms, just try to remember F.A.S.T. These are the first letters of three of the main symptoms of stroke, and a useful reminder. If you think someone with you may have had a stroke, check for these symptoms.

F stands for face. Look at the person’s face to see if it looks as though it has dropped on one side. Check to see whether they can smile, using both sides of their mouth, and if part of their mouth, and the eye on the same side is drooping.

A stands for arms. Check to see if the person can raise both arms and keep them raised. Look for weakness in one or both arms.

S stands for Speech. People who have had a stroke may have slurred speech, or are unable to speak clearly, or at all, even if they seem conscious and aware.

T stands for Time. Don’t wait. If you think that you or someone with you is having or has had a stroke, call 999 and ask for an ambulance to come straight away. The sooner the person having a stroke receives medical help, the more likely they are to have a good recovery.

Act F.A.S.T if you suspect a stroke

What should I do if I have a stroke?

If you are with someone, tell them, or try to let them know by gestures if you can’t speak, that you have had a stroke, and need emergency care and to be taken to a hospital A and E department as quickly as possible.

Recent research led by Professor Peter Rothwell at the University of Oxford suggests that taking aspirin immediately after a TIA or a minor stroke can dramatically reduce your risk of another stroke – and also reduces how serious a follow-up stroke is likely to be. They found that almost all of the benefit of aspirin in reducing the risk of another stroke was in the first few weeks after a TIA or minor stroke.

However, you should not give aspirin to anyone who has had a hemorrhagic stroke, as it could cause further bleeding in the brain (see below).

Findings from the research informed the latest National Clinical Guideline for Stroke which includes advising  that patients with a suspected TIA be given aspirin 300mg immediately.

What is the treatment for stroke?

Having a stroke can be life changing, even life threatening, so it is vital that you get to hospital as quickly as possible. Even though minor strokes – TIAs – may only cause minor symptoms, they may be an early warning sign of a more serious stroke.

The treatment you have in hospital will depend on which type of stroke you have.

Treatment for ischaemic stroke

Ischaemic stroke is the type of stroke cause by a blood clot that prevents blood reaching your brain. This type of stroke is treated with a number of different medicines.

One method involves injecting you with alteplase, a medicine that dissolves blood clots. By doing this it means that blood can reach your brain again. Your doctor may refer to this as ‘clot-busting’ or with its medical term, thrombolysis.

Before you have this treatment you’ll have a computer tomography brain scan (also known as a CT scan). This is to check whether you have had an ischaemic stroke, caused by a clot or a bleed. If you have, the thrombolysis treatment can go ahead. If you have had a bleed you will have a different type of treatment. A CT scan can also show doctors the part of the brain that has been affected.

There is a time limit on treatment with alteplase. It needs to be carried out as soon as possible after you have a stroke. Once four and a half hours have passed since your stroke, it may not have much effect, so this tends to be the cut-off point for this treatment, (although in some cases it can be extended for an hour or so).

According to the Stroke Foundation only about 15% of people who go to hospital because of a stroke can have thrombolysis treatment. Some of the reasons for this are because their stroke has been cause by a bleed rather than a clot; they have had a stroke or other head injury in the last three months, or did not get to the hospital in time for thrombolysis.

In some cases, where the stroke has been caused by a blood clot blocking a large artery in the brain, doctors my carry out a thrombectomy. This involves having a catheter inserted into an artery in your body, which is fed through your arteries to the site of the blood clot in your brain. The clot is then removed, using either suction, or a tiny device that is passed through the catheter. Depending on the circumstances you will be given either a local or general anaesthetic before this procedure begins.

Treatment for a haemorrhagic stroke

 A haemorrhagic stroke is when one of the arteries in your brain bursts, and blood escapes, into your brain. This is an intracerebral haemorrhage. In some cases you may have bleeding onto the surface of your brain. Or you may have bleeding between the fluid-filled layers between the membrane layers. In this case your doctors will say that you have had a subarachnoid haemorrhage.

These types of strokes happen less often than ischaemic strokes, but can cause more damage to your brain.

There are a number of factors that can cause this type of stroke. They include having high blood pressure, which also causes most ischaemic strokes, and having an aneurysm. This is when part of the wall of an artery becomes very thin, and bursts.

Having high blood pressure is one risk factor for having an aneurysm. You may have been prescribed an anticoagulant drug, to stop your blood clotting and so reducing your risk of stroke. However, this can put you at risk of bleeding, so you need to have your health and the drug’s effects, checked regularly.

Where stroke is concerned, it is vital to have your blood pressure checked regularly. If your doctor thinks that you are at risk they will advise you on the steps you can take to reduce your risk, and review your medication.

Are strokes preventable?

Here’s the good news – you can reduce your risk of stroke, by making some changes to your life, and keeping to them.

  • Blood Pressure – have this checked every year – more often if it is high (you can buy inexpensive blood pressure monitors to use at home). Bringing high blood pressure down is one of the best ways to reduce your risk of having a stroke.

How to monitor your blood pressure

  • Stop smoking. This is another very important step to reduce your risk of having a stroke, as smoking can cause damage to your arteries.

Your guide to giving up smoking

  • Have your cholesterol level checked. If it is high talk to your doctor about having treatment to reduce your cholesterol.

Cholesterol: what you need to know

  • If you have diabetes, try to keep your blood sugar levels down to normal levels if you can.

Other steps you can take to reduce your risk include:

  • Keeping to a healthy weight for your height. If you are overweight, try to lose weight by following a healthy diet.
  • Making sure that you take any medicines you’ve been prescribed for medical conditions, and seeing your GP if you feel that you need further help with them.
  • Taking exercise is also important to help you healthy and well.

By taking good care of different aspects of your health, and being aware of the risk factors, you can help to reduce your risk of stroke.

How to reduce your risk of stroke

The opinions expressed are those of the author and are not held by Saga unless specifically stated.

The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.