Your blood pressure is simply a measurement of your
blood as it passes through the arteries. However, high blood pressure can
cause a heart attack or a stroke, which can strike without warning.
The heart pumps at around 70 times a minute to push fresh blood around
the body. The blood has to pass through the arteries and capillaries of the
entire body so that oxygen and other nutrients in the blood can be carried
to every tissue.
WHAT IS BLOOD PRESSURE?
Your blood pressure is the force exerted by the blood on the walls of your
arteries as it flows through them. This pressure is maintained by the
regular pumping action of the heart and the squeezing action of the
relatively thick and muscular walls of the arteries.
The force pushing the blood out of the heart is called the systolic
pressure. This is when the pressure in the arteries is highest.
Between each beat, the heart relaxes and fills up with blood so the
pressure in the arteries falls slightly. The lower pressure during
relaxation is called the diastolic pressure. Together they create a pressure
wave which is what you can feel as your pulse.
When you have your blood pressure taken, the doctor will use an instrument
which is called a sphygmomanometer (from the ancient Greek word sphygmos,
meaning pulse). This can measure both the systolic and diastolic pressure.
To take your blood pressure, the doctor sits you down, supports your arm
at heart level and wraps a cloth cuff containing an inflatable rubber bag
around your upper arm and over the main artery.
The doctor then inflates the bag by squeezing a rubber bulb attached to a
tube. This causes the cuff to contract and press down on the artery. He
continues inflating the bag until the cuff restricts the blood flow through
the artery so much that the pulse beat at the wrist can no longer be felt.
The doctor then deflates the bag and listens with a stethoscope to the
sound of the blood rushing back into the artery. This is the systolic
pressure. He continues to listen while the bag is completely deflated and
the blood is flowing normally through the arteries. At this point the sound
stops. This is the diastolic pressure.
The doctor will check these two measurements against a pressure gauge in the
form of a dial or a calibrated glass tube filled with mercury. The two
measurements are recorded as a fraction, in millimetres (mm) of mercury.
The typical blood pressure of a healthy young person at rest is 120/80,
which means he has a systolic pressure of 120mm and a diastolic pressure of
Our blood pressure goes up and down naturally during the course of the
day. A wide range of factors can influence it. Fear, anxiety or vigorous
exercise push it up, while a nap can make it fall.
Your blood pressure depends on many factors, such as age, sex, diet and
lifestyle. For instance, women's blood pressure tends to rise more slowly
with age until they reach the menopause - one reason why women are at a
lower risk of heart disease and stroke until then.
The combined contraceptive pill can raise blood pressure. This is why
women usually have their blood pressure checked every six months when they
are renewing their pill prescription.
THE SILENT KILLER
If you haven't ever had your blood pressure checked, ask your doctor to test
you and make a note of the result. Doctors recommend having your blood
pressure checked every couple of years after the age of 40, or more often if
your blood pressure is already raised.
Hypertension, or high blood pressure, affects one in 10 adults, but it
often comes as a surprise to discover you have it, as it's usually
symptomless. It may only be picked up during a routine blood pressure check,
during an eye test, or else when it has already caused serious damage such
as following a heart attack or stroke.
Although blood pressure rises naturally as you get older, people who go
on to develop dangerous hypertension find their blood pressure rises more
WHO'S AT RISK
If either of your parents has high blood pressure or had a stroke before the
age of 70, your chance of developing it is around one in three, rising to
three in five if both your parents are affected.
By and large, the heavier you are, the higher your blood pressure - even
in childhood - although even thin people aren't exempt from hypertension,
If your blood pressure remains high for prolonged periods, you run the
risk of it damaging the walls of your arteries. High blood pressure is
medically defined as blood pressure of more than 160/90. Left untreated, it
can cause damage to other organs, particularly the heart, eyes and kidneys.
Your blood pressure and kidney function are closely linked, and some
kidney diseases can cause blood pressure to rise. Scarring of the kidneys as
a result of repeated urinary infections in childhood can lead to
hypertension in adult life.
If you have high blood pressure, making the effort to bring it down can
reduce your risk of a stroke or heart attack dramatically.
Before prescribing drugs, however, the doctor will want to be sure that
the diagnosis of hypertension is correct. Around a quarter of all patients
found to have high blood pressure are actually suffering what is called
'white coat hypertension' - in other words, they get so anxious about seeing
the doctor or being in hospital that their blood pressure goes up.
For this reason, you need to have measurements taken over several weeks
to determine whether you really need drug treatment.
IMPROVING YOUR HABITS
If you do develop hypertension, you'll need to make some changes to your
lifestyle and possibly take medication to keep it in check.
This is vital, as keeping your blood pressure within safe limits can help
reduce your risk of a heart attack or stroke, a blood clot or burst blood
vessel in the brain.
For instance, if you are overweight, bringing your weight down by five to
20 per cent can reduce blood pressure dramatically.
SALT AND YOUR DIET
Cutting down on alcohol can help too, since heavy drinking, and in
particular binge drinking, raises your blood pressure.
A diet high in salt (sodium) can push up blood pressure. You can cut your
daily intake by about half simply by cooking without salt, adding very
little or none to food at the table, and avoiding eating too many processed
foods which are high in salt. Reducing salt intake is a simple but often
very effective way to lower systolic pressure. Another mineral, potassium,
found in fruit and vegetables, is beneficial for your blood pressure.
Aim to reduce salt and increase potassium intake. Salt substitutes are
often based on potassium, though some people dislike the taste of them.
(Very high levels of potassium can be dangerous too but these only tend to
occur in cases of kidney failure.)
HELP FROM EXERCISE
Regular aerobic exercise, such as walking, cycling, swimming or running, can
help lower your blood pressure, even though it actually goes up during
If you already have high blood pressure and are aged 40 or over, check
with your doctor first before you start on an exercise programme.
Relaxation, meditation and stress management may also help some sufferers.
WHEN DRUGS ARE NEEDED
People who have mild to moderate hypertension often don't require drugs.
Instead, they may be able to control their blood pressure by changing their
lifestyle slightly, such as by cutting out salt. But if drugs are needed,
there is a selection available to treat hypertension.
Drugs may be prescribed alone or in combination. Among them are
diuretics, which help to get rid of excess water and sodium, and
beta-blockers, which can inhibit the action of the hormone adrenalin on both
the heart and the circulation. Vasodilators and drugs known as ACE
inhibitors cause the arteries to expand, increasing blood flow and reducing
However, many doctors try to avoid prescribing drugs unless they are
absolutely necessary. The drugs don't always work and side-effects, such as
headaches, swollen ankles, and tiredness, are common.