The heart is a muscular pump. Every time it beats, it forces blood through the arteries and capillaries and around the body.
Blood pressure is the measurement of this force. Two figures are relevant.
The first – the higher figure – is when the heart contracts and forces blood through the arteries.
The second – the lower figure – is when the heart relaxes between beats.
Blood pressure is measured in millimetres of mercury, which is written down as: mmHg.
So, when you have your blood pressure measured, it is written down as two numbers, one over the other like a fraction – 140/90mmHg, for example.
The top number, the systolic pressure, shows the pressure in your arteries when your heart is forcing blood through them.
The bottom number, the diastolic pressure, shows the pressure in your arteries when your heart relaxes.
The top number can be anywhere from 90 to 200, and the bottom number can be anywhere from 60 to 140.
The higher your blood pressure rate, the harder your heart has to work, forcing the blood through arteries which may have narrowed or become stiff.
The strain of pumping the blood at this pressure can cause vessels to become clogged or to weaken, and this can lead to narrow blood vessels and clots which can damage the heart or brain (more rarely, it can lead to the blood vessels bursting). This is what doctors call essential hypertension.
A small number of people have secondary hypertension, which means there is an underlying cause of their high blood pressure.
For example, some people develop high blood pressure if they have problems with their kidneys or adrenal glands (which sit above the kidneys).
These glands produce hormones that are important in controlling blood pressure.
As well as causing heart failure and stroke, high blood pressure can also cause the kidneys to fail.
Who gets high blood pressure?
High blood pressure can affect anyone, but there are high-risk groups:
If you have a family history of high blood pressure, stroke or heart attack, you are more likely to have high blood pressure.
Black and South-East Asian people are more likely to have high blood pressure, although the reasons are not fully understood.
Some other conditions are also linked to high blood pressure, such as diabetes, kidney disease and heart disease.
Blood pressure goes up as we get older. At least half of all people over the age of 75 have high blood pressure.
What are the symptoms of high blood pressure?
High blood pressure usually has no symptoms, which is why many people do not know that they have it. For this reason, it is sometimes called the silent killer.
The only way to know is to have it measured, using a machine with a cuff around your arm.
How can high blood pressure be treated?
Most people in the UK are treated at their GP’s surgery, either by the doctor or practice nurse.
Many surgeries have specific clinics for people with high blood pressure. A few people may need to see someone more specialised in treating blood pressure.
As well as having your blood pressure measured several times, it may be necessary for you to have some simple tests.
Doctors will usually ask you about your family and medical history, take a urine and blood test and may also ask you to have a recording of the electrical activity of your heart (ECG).
Some people may also have blood pressure monitoring over a 24-hour period.
Treatment will depend on how high your blood pressure is and on what other ‘risk factors’ you have for heart disease and stroke.
If your blood pressure is between 140/90 and 160/100mmHg, you will probably be asked to make some changes to your lifestyle. These will include.
Cutting down on the amount of salt in your diet.
Eating at least five portions of fruit and vegetables every day.
Taking more exercise.
Losing weight (if you are overweight).
Cutting down on the amount of alcohol you drink (if it is more than the recommended 21 units a week for men and 14 units for women).
Most people will need to take tablets only if the lifestyle changes don’t work; but some people may be prescribed medication straight away.
This is more likely if you are older or have other risk factors for heart disease and stroke, such as high cholesterol, you are a smoker, or have had a previous stroke or heart attack.
Many doctors encourage patients to manage their own blood pressure by monitoring themselves on a regular basis, especially if they have had a high reading in the past.
You can buy machines for measuring your blood pressure. There is a wide range available, so ask your pharmacist or GP for help if you are unsure which to buy.