RISKS OF HIGH BLOOD PRESSURE

Facts and figures

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-tolick'), is the pressure created by your heart beating and coincides with your pulse; the bottom pressure, known as the diastolic pressure (pronounced 'die-a-stolick'), 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. 120/80 mmHg, 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

Figure 2.3 (a) Healthy arteries are elastic and blood flows easily without meeting a resistance. (b) Arteries can lose their elasticity for

unknown reasons or suffer from disease or hardening with age. They then become less able to relax and a higher pressure is needed to force the blood through.

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 disease the 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 Tests in 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.