Blood pressure measures the force that the blood applies to the walls of the arteries as it flows through them. It’s normal for blood pressure to increase when you exert yourself, or when you feel stressed or anxious. But if the blood pressure is consistently higher than normal at rest, this is high blood pressure, also known as hypertension.
Blood pressure and health
As blood is pumped around the body, it carries oxygen and nutrients that are essential for life. As a result of the pumping action of the heart and the size and flexibility of the arteries that carry blood, the blood is under pressure. This blood pressure is an essential and normal part of the way the body works.
When your nurse or doctor takes your blood pressure, the result is expressed as two numbers such as 120/80 (“one hundred and twenty over eighty”). The top figure – the systolic blood pressure – is a measure of the pressure when your heart muscle is contracted and pumping blood. The bottom figure – the diastolic blood pressure – is the pressure when the heart is relaxed and filling with blood.
A diagnosis of hypertension is made if you have a blood pressure of 160/90 or higher. If your blood pressure is close to this, your doctor will probably want to monitor it regularly. If you suffer from diabetes, it is even more important that your blood pressure is lower than this – ideally less than 130/80. For more details, see Blood pressure monitors, below.
People with hypertension have an increased risk of major illnesses including:
• cardiovascular disease including angina, heart attack and stroke
• kidney damage
• eye problems
• circulation problems in their legs, which could eventually lead to gangrene
However, the risk of cardiovascular disease is linked to other factors including whether or not you smoke, have diabetes or high cholesterol. Slightly raised blood pressure may not need to be treated so aggressively if other risk factors do not apply to you.
Hypertension is a big problem in the UK – about half of people aged between 65 and 74 are affected.
Types of hypertension
Types of hypertension Most people with high blood pressure – 95% – have what’s called primary or essential hypertension. This means that there’s no single clear cause of it.
Although it’s known that some factors to do with lifestyle can contribute to hypertension (see above), we don’t precisely In association with 40 ISSUE 1 2004 PHARMACEUTICAL FIELD understand why some people get it and others do not.
However, hypertension can run in families, and you are more likely to be affected if your close relatives are too.
But you are also more likely to develop hypertension if you:
• are obese (very overweight)
• drink a lot of alcohol
• eat a lot of salt
• are under a lot of stress
You may be among the other 5% of people with high blood pressure who have what’s known as secondary hypertension. This means your condition can be linked to a recognised cause – in fact, it may be a symptom of another underlying disease.
Secondary hypertension can be caused by:
• kidney disease.
• adrenal gland disease.
• narrowing of the aorta
Secondary hypertension can also be caused by the contraceptive pill (rarely), or steroids, or by pregnancy causing pre-eclampsia.
Most people with hypertension don’t have any symptoms. In fact, you may not even know you have a problem: most people are diagnosed when they have their blood pressure taken as part of a medical examination. That’s one good reason to have a regular check up with your doctor, especially if you’re over 65.
You may have heard that people with high blood pressure experience headaches and dizziness. However, in most cases, that’s not so. Only people with severe hypertension or a rapid rise in blood pressure are likely to experience warning headaches, blurred or impaired vision, fits or black-outs.
Before starting you on any course of treatment for hypertension, your doctor will give you a physical examination. You may be asked to come back for repeat measurements over a number of weeks to check that the high reading is an ongoing problem and not a one-off.
You may also need some tests, to see if hypertension is having an effect on the rest of your body. These may include:
• analysis of your urine (protein in your urine may be the first sign of a kidney problem)
• a blood test, to check the condition and working of your kidneys
• a chest X-ray, to identify any enlargement of the heart muscle
• an ECG (electrocardiogram), to look for any heart strain
• eye checks
If you have very severe hypertension, you may need to be admitted to hospital for initial treatment. But it’s much more likely that your will be cared for by your GP and/or a nurse specialist, or the practice nurse, based at the surgery.
First, your doctor or nurse is likely to discuss lifestyle changes which might help. He or she might, for example, advise you to:
• start to lose any excess weight
• get some regular moderate exercise
• cut down on salt and alcohol
• stop smoking
• have stress management or relaxation therapy
If your blood pressure remains high, one or more of the following antihypertensive drugs may be prescribed for you.
• Diuretics, which increase the amount of salt and water removed from your blood by your kidneys, and widen your arteries. Eg bendrofluazide
• Beta-blockers, which reduce the work your heart has to do, by reducing your pulse rate. Eg atenolol
• ACE inhibitors or angiotensin 2 receptor antagonists, which block enzymes that constrict the blood vessels. Eg captopril, losartan
• Calcium channel blockers or alpha blockers, which help widen your blood vessels. Eg nifedipine
The drugs you are prescribed will depend on a number of factors, including their side effects, your other risk factors for cardiovascular disease and if you have any other illnesses. For example, if you get asthma, beta-blockers may not be suitable for you.
It is important to understand the benefit of having hypertension under effective control. This is because there is a commitment involved in taking any necessary medication every day for a condition that may have no symptoms.
It may take time to find the best treatment for you, balancing the benefits against any side-effects.
Blood pressure monitors
You might consider getting a blood pressure monitor to use yourself at home – discuss this option with your doctor, who should be able to help you choose a suitable one. If you do decide to buy one, go for a model that takes a measurement from your upper arm rather than your wrist or finger. And look for evidence that it has been “clinically validated” – proven to consistently match the readings given by professional monitors.
The unit of measurement for blood pressure is millimetres of mercury – or mmHg (where Hg is the chemical symbol for mercury). This is because the traditional blood pressure monitor – known as a spyhgmomanometer – uses a column of mercury to measure pressure. The same units are used for electronic blood pressure monitors.