What are the causes of high blood pressure?

people on clouds illustration - high blood pressure

Dr Neil Chapman, Consultant in general and cardiovascular medicine and clinical pharmacology at Hammersmith and St Mary's hospitals, explains high blood pressure and updates us on how the BHF is tackling it.

What is blood pressure?

Blood pressure is the pressure of the blood in your arteries. Blood pressure readings consist of two numbers, usually shown as one on top of the other and measured in mmHg (millimetres of mercury). If your reading is 120/80mmHg your doctor or nurse may refer to it as ‘120 over 80’. The first (top) number represents the highest level your blood pressure reaches when your heart contracts – known as your systolic pressure. The second (bottom) number represents the lowest level your blood pressure reaches as your heart relaxes between beats – your diastolic pressure.

High blood pressure (hypertension) means your blood pressure is constantly above recommended levels. Unless your doctor says otherwise, blood pressure should be below 140/90. Those with heart disease, diabetes or kidney disease, should ideally have a reading below 130/80.

Blood pressure readings consist of two numbers, usually shown as one on top of the other and measured in mmHg (millimetres of mercury).

What’s the scale of the problem?

High blood pressure affects around 16 million people in the UK. An estimated seven million of those are undiagnosed, as there are rarely any symptoms. You may only find out you’ve got a problem when you have a heart attack or stroke. High blood pressure contributes to around half of all heart attacks and strokes in the UK.

Who is at risk of high blood pressure?

Risk factors include being overweight, having too much salt in your diet, not doing enough physical activity, drinking too much alcohol and a having family history of high blood pressure. We also know that people from an African Caribbean background and people living in deprived areas may be at higher risk. 

How can it be prevented?

Maintaining a healthy weight, reducing salt, eating plenty of vegetables and fruit, and being physically active all help. These are important even if you’re on medication to reduce blood pressure. 

Maintaining a healthy weight, reducing salt, eating plenty of vegetables and fruit, and being physically active all help.

How will I know if I have high blood pressure?

Have it measured. In England, adults aged 40–74 can get a free NHS Health Check via their GP (and at some pharmacies). There are similar schemes in Northern Ireland, Scotland and Wales. If you’re under 40 and think you might be at risk of high blood pressure, ask your GP for a test.

Do I need to take medications?

Blood pressure medication reduces the risk of heart attack and stroke in people with hypertension. But current UK guidance does not recommend medication for everyone. If your blood pressure is only slightly raised, your doctor will do simple blood and urine tests (including checking cholesterol and blood sugar levels), perform an ECG and consider your medical history to decide if you need it.

cloud illustration measuring blood pressure bhf

What about side effects?

Any drug can have side effects. These are often mild but can mean you have to stop a particular drug. Your doctor should explain this when you are first prescribed it. If you do develop side effects, discuss them with your doctor. Different drugs act in different ways, so you could be fine with an alternative.

Are there other issues with high blood pressure medication?

It can be hard to predict which drugs will work for you, but we know some are less effective in older people or those of African Caribbean background. Most people will need more than one drug to control their blood pressure.

It is estimated that more than half of patients do not take their medications as prescribed. This contributes to poor blood pressure control and increased risk of stroke and heart attack.

Part of the problem is that with hypertension, the condition itself usually does not cause symptoms that remind you to take medications. Asking your doctor for once-a-day tablets and building it into your daily routine can help. A dosette box (pill box with compartments for each day, and times of the day if necessary) may help. You can get them at most pharmacies and some GP surgeries.

Have you been involved in any blood pressure research that is changing current practice?

One of the most important research trials I’ve been involved with is the BHF-funded PATHWAY-2 study looking at the best drug for people with resistant hypertension. This study compared drugs to identify the best fourth-line medication to use in patients whose blood pressure was not controlled, despite already taking three drugs. It demonstrated that a relatively old drug called spironolactone was better than other drugs tested in the trial.

Although spironolactone was already recommended as a possible option for resistant hypertension in NICE [National Institute for Health and Care Excellence] blood pressure guidelines, the results of PATHWAY-2 will hopefully improve blood pressure control in this challenging patient group.

If you or a family member are interested in taking part in clinical trials like this one, visit the UK Clinical Trials Gateway.

 BHF blood pressure action bhf advice blood pressure

The BHF is determined to tackle high blood pressure. We set up a Blood Pressure Programme dedicated to preventing, detecting and managing high blood pressure, with a focus on those at highest risk. 

The team is reviewing options for convenient community locations  for blood pressure testing, such as local pharmacies, workplaces, supermarkets, community centres and places of worship. We want to make testing as easy as possible.

Recent research suggests that only 37 per cent of all people with high blood pressure have their condition under control. The BHF Blood Pressure Team, alongside Public Health England and other healthcare professionals, are working on projects to address this. We are reviewing our resources, which include booklets, videos and online tools to help you understand and manage your own blood pressure at home.

We’re dedicating an area of our website to key information on high blood pressure and how to control it, for patients and healthcare professionals.

Jamie Waterall, Chair of the National Blood Pressure System Leadership Board at Public Health England, says: “Everyone has a part to play when it comes to helping reduce the nation’s blood pressure. The System Leadership Board was established to ensure a joined-up approach towards tackling high blood pressure. It published Tackling high blood pressure: from evidence into action, setting out priority actions. I would like to congratulate the BHF for their leadership in reducing the population’s blood pressure.We know that many heart attacks could be avoided and many lives saved if we work together.”

The BHF is funding numerous research projects, including one looking at the best time to take medication and another looking at how your genes could influence your blood pressure. Over the past seven years, we’ve invested £35–40m on research into blood pressure.

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