Can you tell me more about blood pressure? Why is it serious if it becomes high?

W e need a blood pressure to send blood around our bodies (see Chapter 1). It is needed to overcome the resistance of the smaller blood vessels. The arteries in the body have muscle in their walls to give them tone. If this muscle is supple, the arteries can relax, their size or width increases and blood flows more easily. Think of the artery like a garden hose pipe: if you turn the tap on, water flows easily – now clamp the pipe to reduce its size by half and water will need more pressure to get through to give the same flow. In a similar way, the heart pumps the blood through the arteries but, if your arteries get smaller, the pressure will need to rise in order to force the blood through (see Figure 2.3). The top pressure,known as the systolic pressure(pronounced ‘sis-tol-ick’),is the pressure created by your heart beating and coincides with your pulse; the bottom pressure, known as the diastolic pressure (pronounced ‘die-a-stol-ick’), is the reading when your heart is relaxing. The readings should not be more than 140/90 mmHg. Hg is the symbol for mercury which used to be in the column of the blood pressure machine.
Blood pressure can clearly be raised at rest, for example 220/120mmHg (when it is known as hypertension, see below) or normal, e.g.120/80mmHg, but there are areas where it is borderline, and you need regular checks to keep an eye on it. A pressure consistently above 140/90 mmHg should be investigated, but age should be taken into account as well. At 80 years this figure might be okay, but at 30 years it would not be. So although doctors talk generally of blood pressure, any decision to investigate or treat will be made on a very individual basis.
Hypertension(pronounced ‘hi-per-ten-shun’) is the medical word for a high blood pressure. ‘Hyper’ means too much, and ‘tension’ refers to the pressure. You may be asked to attend a hypertension clinic or a screening clinic to keep a check on your blood pressure.
What causes high blood pressure?
In the vast majority of cases there is no single cause, just as there is no single cause for people being short or tall. The medical name is essential or primary hypertension. Tests may be done to check the kidneys, adrenal gland and heart. Some people’s blood pressure is raised as a side effect of their medication, particularly anti-arthritis

medications. Always tell your doctor or practice nurse what medicines you have (including complementary or herbal medicines) or, preferably, bring along any that you are taking to show your doctor. You may have been told that you have secondary hypertension– this is the term used when a cause for your high blood pressure has been found (this happens in only 5% of cases). The normal or target pressure is 140/90 mmHg or less. In people with diabetes, chronic renal disease or coronary diseasethe target is 130/80 mmHg.

What tests can I expect to have if my blood pressure is found to be raised?
The heart may be checked with an ECG (see under Tests in Chapter 3) or echocardiogram (see under Testsin Chapter 5). A chest X-ray may be taken to look at the heart and lungs. Blood and water (urine) tests will look for any signs of anaemia (low blood count) or kidney problems, and your urine may be collected for 24 hours to see if there is too much adrenaline coming from your adrenal gland. Sometimes a scan or X-ray is taken of the kidneys.

I am not too sure what the adrenal glands are for. Can you explain their purpose?

The adrenal glands sit on top of your kidneys. They produce adrenaline. This is a hormone which speeds up your heart when you exert yourself or are emotionally excited or very frightened (white with fear), and you feel your heart pounding. Adrenaline keeps your blood pressure up if you are shocked or losing blood. Too much adrenaline that is not needed, for example in a person who is not exercising, will keep the blood pressure high unnecessarily. A tumour of the adrenal gland can do this and, although they are very rare, we check the blood or urine for excess adrenaline in younger people. If an excess is found and a tumour shown on a scan, it can be removed surgically.

When I went to the clinic to have my blood pressure checked, I was told that I had white coat hypertension. What is this?
T his is a high reading caused by anxiety or stress when you visit your doctor –who may be wearing a white coat! At other times your blood pressure is usually normal. It may be worth checking the readings at home and during the day with a blood pressure machine that can be worn while you are walking about (an ambulatory machine; see the question later on about this.) Do several readings with your own or a borrowed machine. Blood pressure often rises under stress; throughout the day we are exposed to many stresses, so if several elevated readings occur because of environmental stress, treatment will be of value. If no elevated readings occur, your doctor should monitor your pressure regularly anyway, because we don’t know if white coat hypertension is a warning for true hypertension in the future. You cannot afford to be complacent.

When I was 16, my blood pressure was lower than it is now that I am 45. Is this OK?

Yes, as a natural part of growing old, your arteries tend to lose their elastic properties to some degree. Also, the walls of your arteries tend to thicken after middle age and, consequently, the internal diameter of the vessel is slightly reduced (the hose pipe gets narrower). All these changes require a very slight increase in blood pressure, which is perfectly normal as you get older.

What are the dangers if I can’t get my high blood pressure down?

If a raised blood pressure is left untreated over a 12-year period, you are more likely to die from this risk than if you had been treated. Here are some other statistics about raised blood pressure.
•    It is present in 70% of people who have a stroke.
•    It increases the risk of coronary heart disease by 2–3 times for men and women.
•    It causes heart and kidney failure.
•    It causes hardening of the arteries to the legs resulting in pain on walking owing to poor blood flow. The medical term for this isclaudication, pronounced ‘claw-dee-ca-shun’.
•    It is responsible for a third of all heart diseases.


•    It causes 7out of 10 strokes in women and 4out of 10 in men.
•    In the UK, 300 people die every 6 weeks as a result of a high blood pressure and most of these deaths are avoidable;if a jumbo jet with 300 people on board crashed every 6 weeks, something would be done about it!

Are there any specific risk factors for high blood pressure that might apply to me?

You are more likely to have a high blood pressure if you: • have someone in your family who has had high blood pressure;
•    are African-Caribbean;
•    are aged over 60 years of age;
•    are very overweight;
•    drink heavily;
•    eat a lot of salt;
•    had a high blood pressure in pregnancy, or pre-eclampsia;
•    have a lot of stress in your life.

I have read about the rule of halves, but did not understand it. Could you explain?

This is a medical paradox but in reality it demonstrates some alarming facts about blood pressure and lack of treatment.
•    Half the people with high BP have not been diagnosed.
•    Half of those diagnosed have not been treated.
•    Half of those treated have not got their blood pressure under control.

•    Half of those treated are well treated.
•    Only one-eighth of people with high blood pressure are being properly treated (see Figure 2.4).

So the responsibility is yours to keep nagging your doctor or practice nurse to check your blood pressure, whenever you go to the surgery. You must take charge of your own health.

How would I know if my blood pressure was raised?

Most people feel nothing until there is a problem, which is why it is known as ‘the silent enemy’. It is thought that half the people with high blood pressure do not know they have it, because they cannot feel it and a doctor has not checked it. It is therefore important to have a blood pressure check every few years if it is normal, or more frequently if it is slightly raised or ‘borderline’. If you go to your doctor for another reason, ask for it to be checked then.