Ischaemic Stroke And Hypertension

Did you know that in the UK, a stroke occurs once every five minutes? It is the fourth leading cause of death nationwide responsible for a death every 17 minutes. Hypertension happens to be the greatest risk factor for stroke.

Understanding this link between ischaemic stroke and hypertension is crucial for taking preventive measures and managing both conditions effectively.

Ischaemic stroke

A stroke is a serious life-threatening medical condition that happens when the blood supply to your brain is blocked or reduced. With limited blood flow, the brain cells can get damaged due to insufficient amounts of oxygen and nutrients they need. As the brain controls all our body’s functions, the damage caused by a stroke is associated with a wide range of disabilities. 

Depending on which part of the brain has had the disrupted blood supply, the damage can impact your cognitive, emotional or behavioural changes.

Symptoms of a stroke

It is important to empower yourself with knowledge of stroke, as spotting the symptoms is the fastest way to save someone's life. The longer your brain is deprived of oxygen and nutrition, the more irreversible damage may occur. 

Research has shown that if the treatment for restoring blood flow for strokes is not initiated within 6.3 hours after the onset of symptoms, the treatment will not provide any therapeutic benefit or improve the patient's condition.¹ Immediate treatment is suggested to minimise the long-term effects of a stroke and prevent death. 

Call 999 immediately if you’re worried that you or someone you’re with is having a stroke. Even if the symptoms disappear quickly, it is still a medical emergency as the blockage in blood flow might happen again or somewhere else, which requires treatment straight away.

This is how you can act F.A.S.T. by being aware of the main symptoms of stroke:

• F (Face Drooping) – the face may have dropped on one side, the person may not be able to smile evenly, or their mouth or eye may have dropped
• A (Arm Weakness) – the person may not be able to lift both arms and keep them there because of weakness or numbness in one arm
• S (Speech Difficulty) – their speech may be slurred or garbled, or the person may not be able to talk at all despite appearing to be awake; they may also have problems understanding what you're saying to them
• T (Time to call 999) – dial 999 immediately if you see any of these signs or symptoms and note the time when any of the symptoms first appear

Here are other symptoms that the stroke might present:

• Numbness or weakness of face, arm, or leg, especially only on one side of the body
• Confusion, trouble speaking or understanding speech
• Trouble seeing in one or both eyes
• Trouble walking, loss of balance or coordination
• Dizziness, or severe headache with no known cause

Types of stroke

Ischaemic stroke

According to the NHS, ischaemic stroke is the most common type of stroke, accounting for around 85% of all cases in the UK. It happens when a blood clot blocks the flow of blood and oxygen to the brain, causing damage to your brain cells.

Haemorrhagic stroke

Haemorrhagic stroke is when you have bleeding in or around the brain by the rupture of a blood vessel. Based on different bleeding locations, haemorrhagic stroke may be further subdivided into bleeding within the brain, intracerebral haemorrhage (ICH), bleeding on the surface of the brain, subarachnoid haemorrhage (SAH). Haemorrhagic strokes are a less common type of stroke that accounts for approximately 15% of strokes in the UK. 

Transient ischaemic attack (TIA)

It is often referred to as a mini-stroke. Its mechanism is the same as an ischaemic stroke, blocking the blood supply by a clot in your brain but it only happens temporarily. When the clot moves away, the stroke symptoms stop; hence why it might last for a shorter time.

Although you might feel fine afterwards, it is still considered an urgent medical condition where early intervention is required. Early treatment after a TIA can significantly reduce the risk of strokes.² After an episode of TIA, the risk of stroke within 3 months has been reported to be around 20%, with approximately 50% of these strokes occurring within the first 2 days.²

Cause of stroke

The cause of stroke can be categorised into non-modifiable and modifiable. Here are some common established causes:

Modifiable risk factors include

• Hypertension: High blood pressure is when the force of blood pushing against your artery walls is consistently too high. If left untreated over time, it could damage your arteries and can lead to serious complications like heart attack and stroke
• Diabetes mellitus: Diabetes can damage blood vessels at various locations which could lead to stroke if brain vessels are directly affected³
• Cardiovascular disease: for example, atrial fibrillation, a condition where your heart pumps irregularly leading to a chance of blood clot formation
• High cholesterol: It is a condition where your fat builds up in the artery. The damaged arteries and the clot forming from the breakdown of the fat can both cause stroke
• Previous stroke
• Lifestyle issues: Excessive alcohol intake, tobacco use, illicit drug use, physical inactivity, and obesity⁴

Non-modifiable risk factors include

• Age: The incidence doubles for each decade after age 55 years⁴
• Race: In younger black adults the risk of ICH is twice that of age-matched white people⁴
• Sex: Stroke is more likely to be presented in females than in males with a possibility of the risk of pregnancy and oral contraceptive use⁴
• Ethnicity: African Caribbean individuals in the UK have twice the risk of incident stroke compared with their white counterparts. This may be related to the increased stroke risk factors, such as uncontrolled hypertension, obesity and diabetes⁴
• History of migraine headaches: evidence showed that individuals with migraine are approximately 2 times more likely to develop an ischaemic stroke⁵
• Genetics: in addition to the gene disorders that are associated with stroke, such as sickle cell disease, other medical conditions that run in your family may also be the contributors, such as hypertension⁴

Relationship between ischaemic stroke and hypertension

Now, we already know hypertension is a risk factor for stroke. But do you know that hypertension and its consequences are associated with over 50% of ischaemic and 70% of haemorrhagic strokes, and despite good control of blood pressure, there remains a 10% risk of recurrent stroke-related events?⁶

How does hypertension cause ischaemic stroke?

Healthy arteries are flexible, strong and elastic. Their inner wall is smooth so that blood flows freely, supplying your brain and other organs with nutrients and oxygen. When they are constantly exposed to high pressure, they will start to lose their elasticity, eventually becoming stiff and weak, and prone to accumulate a build-up of fatty material. This process is called atherosclerosis. When the debris breaks down from this fatty material, it could travel along with the blood flow and if it clots in your brain vessel it would cause an ischaemic stroke or a TIA.⁷

Moreover, studies also show that hypertension decreases your brain’s blood flow. The change in the cerebral blood flow will directly damage your brain and its activities. When your endothelial cells, a protective interior layer of cells of your vessels, get damaged, it will release a substance to interrupt the stability of your blood flow.⁷

This process is responsible for a wide range of cardiovascular conditions, for example, atherosclerosis, stroke and cerebral small vessel diseases.^7,8 Cerebral small vessel disease is a general term to describe damage in small blood vessels located in your brain, which is responsible for approximately 25% of ischaemic strokes and 45% of vascular dementia.⁸

How to prevent strokes?

Here are some tips on how to minimise the risk of developing a stroke suggested by the UK Stroke Association.

Control your medical conditions

Untreated high blood pressure is the biggest risk factor for stroke. Luckily, hypertension is also the most prevalent risk factor for stroke. Talk with your doctor about how to manage your hypertension and other conditions also considered risk factors, such as high cholesterol, diabetes, heart diseases, and atrial fibrillation. Adhering to your treatment and following your GP’s recommendation are the primary ways to minimise your risks of stroke and other complications.

Stopping smoking

Smoking makes your vessels lose elasticity and makes your blood more likely to clot. Research indicates that current smokers are 2-4 times more likely to have strokes compared with nonsmokers or individuals who had quit smoking more than 10 years prior.⁹

Drinking sensibly

Drinking too much alcohol raises your blood pressure. Also, Some types of drugs can increase your risk of stroke by damaging your blood vessels and raising your blood pressure. 

Eating healthily

A good balanced diet can help prevent hypertension, heart disease and diabetes.

Keeping physically active

Just 30 minutes of exercise five days a week can halve your risk of having a stroke.

Consulting your GP

Many things in life, like work issues and family problems, can lead to stress and depression. This might not show an immediate impact on your health but if left untreated this can lead to long-term health problems. Moreover, earlier we mentioned oral contraceptive pills and other non-modifiable contributors, like ageing, are also potential risk factors. Therefore, if you’re having concerns towards your established risk factors or you’ve experienced a stroke and would like to know how to prevent it from happening again, contact your GP and have a medical evaluation on your general health condition.

Summary

Stroke is one of the leading causes of death and disability in the UK, occurring once every 5 minutes. An ischaemic stroke occurs when a blood clot blocks blood flow to part of the brain, depriving it of oxygen and nutrients. Hypertension is the greatest risk factor for stroke. It damages and stiffens blood vessels over time, increasing stroke risk through atherosclerosis and blood clots. Managing your medical conditions, like hypertension, and making lifestyle changes can highly minimise your risk of developing stroke.