What is blood pressure?
Blood pressure is the pressure of blood in your arteries (blood vessels). Blood pressure is measured in millimetres of mercury (mmHg). Your blood pressure is recorded as two figures. For example, 150/95 mmHg. This is said as '150 over 95'.

The top (first) number is the systolic pressure. This is the pressure in the arteries when the heart contracts.
The bottom (second) number is the diastolic pressure. This is the pressure in the arteries when the heart rests between each heartbeat.


What's classed as high blood pressure?

There is a natural tendency for blood pressure to rise with age due to the reduced elasticity of the arterial system. Age is therefore one of the factors that needs to be taken into account in deciding whether a person's blood pressure is too high.

In general terms, people with a systolic blood pressure consistently above 160mmHg and/or a diastolic pressure over 100mmHg need treatment to lower their blood pressure.

People with mild 'higher' blood pressure (140-159mmHg systolic or 90-99mmHg diastolic) may need treatment if they have a high risk of developing or have cardiovascular disease, eg stroke or angina (chest pains), diabetes, heart or kidney damage due to aprevious high blood presssure.


What causes hypertension?

For more than 90 per cent of people with high blood pressure, the cause is unknown. This is called 'primary' or 'essential hypertension'. It is thought that slight narrowing of the arteries increases the resistance to blood flow, which increases the blood pressure. The cause of the slight narrowing of the arteries is not clear. Various factors probably contribute.

In the remaining 10 per cent or so, there is an underlying cause. This is called 'secondary hypertension'.

Some of the main causes for secondary hypertension are:

- chronic kidney diseases
- diseases in the arteries supplying the kidneys
- chronic alcohol abuse
- hormonal disturbances
- endocrine tumours


What are the signs and symptoms of high blood pressure (hypertension)?

Hypertension is usually found incidentally - "case finding" - by healthcare professionals during a routine checkup. The only test for hypertension is a blood pressure measurement. Hypertension in isolation usually produces no symptoms although some people report headaches, fatigue, dizziness, blurred vision, facial flushing or tinnitus.

Malignant hypertension (or accelerated hypertension) is distinct as a late phase in the condition, and may present with headaches, blurred vision and end-organ damage.

Hypertension is often confused with mental tension, stress and anxiety. While chronic anxiety and/or irritability is associated with poor outcomes in people with hypertension, it alone does not cause it. Accelerated hypertension is associated with somnolence, confusion, visual disturbances, and nausea and vomiting (hypertensive encephalopathy).


Complications of high blood pressure

While elevated blood pressure alone is not an illness, it often requires treatment due to its short- and long-term effects on many organs. The risk is increased for:

-Cerebrovascular accident (CVAs or strokes)
-Myocardial infarction (heart attack)
-Hypertensive cardiomyopathy (heart failure due to chronically high blood pressure)
-Hypertensive retinopathy - damage to the retina
-Hypertensive nephropathy - chronic renal failure due to chronically high blood pressure


How common is high blood pressure?

In the UK, about half of people over 65, and about 1 in 4 middle aged adults, have high blood pressure. It is less common in younger adults. Most cases are mildly high (up to 160/100 mmHg). However, at least 1 in 20 adults have blood pressure of 160/100 mmHg or above. High blood pressure is more common in people:

- with diabetes. About 3 in 10 people with Type 1 diabetes and more than half
- of people with Type 2 diabetes eventually develop high blood pressure.
- from African-Caribbean origin.
- from the Indian sub-continent.
- with a family history of high blood pressure.
- with certain lifestyle factors. That is, those who: are overweight, eat a lot of salt, don't eat many fruit and vegetables, don't take enough exercise, or drink a lot of alcohol.


What are the risk factors of high blood pressure (hypertension)?

Anyone can suffer from high blood pressure, but certain factors can seriously aggravate hypertension and increase the risk of complications:

- a family history of high blood pressure
- high cholesterol or high triglyceride (fat) blood level
- kidney disease
- diabetes
- age, the older you are the more susceptible to high blood pressure you are
- post menopausal women
- ethnicity, those of Afro-Caribbean or Indian (and sub continent) descent
- certain medication such as steroids
- lifestyle factors include - smoking, poor diet (high salt intake), lack of exercise, excessive alcohol consumption, being overweight.


Ways of lowering your blood pressure or reducing the risk

Often just changing your lifestyle can help reduce the risk of having a raised blood pressure:

- stop smoking
- lose weight if you are overweight
- enjoy regular exercise (aim for 30 mins five times a week)
- eat a healthy and varied diet, cut back on fat, reduce the amount of salt intake, chose healthier oils such as grapeseed, olive oil or sunflower, try to include 2-3 portions of fish, as these contain Omega-3 which is good for your heart.
- drink alcohol in moderation (men should only be having 21 units of alcohol per week and women 14 units, a unit is classed as half a pint of beer, a small glass of wine or one spirit measure)
- reduce stress by trying different relaxation techniques


Medication

If prescribed, medication can help lower your blood pressure:

- Ace inhibitors are a drug that stops the production of a chemical called Angiotensin II which causes the muscles surrounding blood vessels to contract, thereby narrowing the vessels causing high blood pressure.

- Angiotensin II receptor antagonists. These drugs have a similar action to Ace Inhibitors whereby they block the action of te chemical Angiotensin II, dilating the blood vessels, lowering blood pressure.

- Alpha blockers. These are drugs that block receptors in arteries relaxing the blood vessels leading to an increase in blood flow, lowering blood pressure.

- Beta blockers. These drugs block adrenergic substances such as adrenline and the sympathetic nervous system in the body. This relaxes the heart, slows the heart beat thus reducing blood pressure.

- Calcium-channel blockers. When calcium enters the muscle cells of the heart it causes the heart to contract and arteries to narrow. Calcium-channel blockers block the entry of calcium, dilting the arteries thus reducing muscle tension leading to an increase in blood flow.

- Diuretics. Diuretics work by helping the body get rid of excess salt and water via the kidneys, therefore reducing blood pressure.

Never stop taking your medication without consulting your GP, even if you feel fine. Hypertension can lead to serious complications if left untreated.

If there is a family history of high blood pressure you should have regular blood pressure checks.


What are targets for blood pressure

In people that are generally well

- systolic pressure of less than 140mmHg
- diastolic pressure of less than 85mmHg

In people who have other diseases such as diabetes, cardiovascular disease, chronic kidney disease the targets are lower

- systolic pressure of less than 130mmHg
- diastolic pressure of less than 80mmHg


For further help and information visit The British Hypertension (high blood pressure) Society on our Further Information and Support Group page.