Means high BLOOD PRESSURE (raised pressure of the circulating blood), but since there is a wide range of ‘normal’ blood pressure in the population, a precise level of pressure above which an individual is deemed hypertensive is arbitrary. (A healthy young adult would be expected to have a systolic pressure of around 120 mm Hg and a diastolic of 80 mm Hg, recorded as 120/80.) Hypertension is not a disease as such but a quantitative deviation from the norm. A person with a pressure higher than the average for his or her age group is usually symptomless – although sometimes such people may develop headaches. The identi?cation of people with hypertension is important because it is a signal that they will be more likely to have a STROKE or myocardial infarct (coronary thrombosis or heart attack) than someone whose pressure is in the ‘normal’ range. Preventive steps can then be taken to lessen the likelihood of their developing these potentially life-threatening conditions.
Blood pressure is measured using two values. The systolic pressure – the greater of the two – represents the pressure when blood is pumped from the left VENTRICLE of the heart into the AORTA. The diastolic pressure is the measurement when both ventricles relax between beats. The pressures are measured in millimetres (mm) of mercury (Hg). Despite the grey area between normal and raised blood pressure, the World Health Organisation (WHO) has de?ned hypertension as a blood pressure consistently greater than 160 mm Hg (systolic) and 95 mm Hg (diastolic). Young children have readings well below these, but blood pressure rises with age and a healthy person may well live symptom free with a systolic pressure above the WHO ?gure. A useful working de?nition of hypertension is the ?gure at which the bene?ts of treating the condition outweigh the risks and costs of the treatment.
Between 10 and 20 per cent of the adult population in the UK has hypertension, with more men than women affected. Incidence is highest in the middle-aged and elderly. Because most people with hypertension are symptomless, the condition is often ?rst identi?ed during a routine medical examination, otherwise a diagnosis is usually made when complications occur. Many people’s blood pressure rises when they are anxious or after exercise, so if someone’s pressure is above normal at the ?rst testing, it should be taken again after, say, 10 minutes’ rest, by which time the reading should have settled to the person’s regular level. BP measurements should then be taken on two subsequent occasions. If the pressure is still high, the cause needs to be determined: this is done using a combination of personal and family histories (hypertension can run in families), a physical examination and investigations, including an ECG and blood tests for renal disease.
Over 90 per cent of hypertensive people have no immediately identi?able cause for their condition. They are described as having essential hypertension. In those patients with an identi?able cause, the hypertension is described as secondary. Among the causes of secondary hypertension are:
Lifestyle factors such as smoking, alcohol, stress, excessive dietary salt and obesity.
Diseases of the KIDNEYS.
Pregnancy (ECLAMPSIA).
Various ENDOCRINE disorders – for example, PHAEOCHROMOCYTOMA, CUSHING’S DISEASE, ACROMEGALY, thyrotoxicosis (see under THYROID GLAND, DISEASES OF).
COARCTATION OF THE AORTA.
Drugs – for example, oestrogen-containing oral contraceptives (see under CONTRACEPTION), ANABOLIC STEROIDS, CORTICOSTEROIDS, NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).
Treatment People with severe hypertension may need prompt admission to hospital for urgent investigation and treatment. Those with a mild to moderate rise in blood pressure for which no cause is identi?able should be advised to change their lifestyle: smokers should stop the habit, and those with high alcohol consumption should greatly reduce or stop their drinking. Obese people should reduce their food consumption, especially of animal fats, and take more exercise. Everyone with hypertension should follow a low-salt diet and take regular exercise. Patients should also be taught how to relax, which helps to reduce blood pressure and, if they have a stressful life, working patterns should be modi?ed if possible. If these lifestyle changes do not reduce a person’s blood pressure su?ciently, drugs to achieve this will be needed. A wide range of anti-hypertensive drugs are available on prescription.
A ?rst-line treatment is one of the THIAZIDES, e?ective at a low dosage and especially useful in the elderly. Beta blockers (see BETAADRENOCEPTOR-BLOCKING DRUGS), such as oxprenolol, acebutol or atenolol, are also ?rst-line treatments. ACE inhibitors (see ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS) and CALCIUM-CHANNEL BLOCKERS can be used if the ?rst-line choices are not e?ective. The drug treatment of hypertension is complex, and sometimes various drugs or combinations of drugs have to be tried to ?nd what regimen is e?ective and suits the patient. Mild to moderate hypertension can usually be treated in general practice, but patients who do not respond or have complications will normally require specialist advice. Patients on anti-hypertensive treatments require regular monitoring, and, as treatment may be necessary for several years, particular attention should be paid to identifying sideeffects. Nevertheless, e?ective treatment of hypertension does enable affected individuals to live longer and more comfortable lives than would otherwise be the case. Older people with moderately raised blood pressure are often able to live with the condition, and treatment with anti-hypertensive drugs may produce symptoms of HYPOTENSION.
In summary, hypertension is a complex disorder, with di?erent patients responding di?erently to treatment. So the condition sometimes requires careful assessment before the most e?ective therapy for a particular individual is identi?ed, and continued monitoring of patients with the disorder is advisable.
Complications Untreated hypertension may eventually result in serious complications. People with high blood pressure have blood vessels with thickened, less ?exible walls, a narrowed LUMEN and convoluted shape. Sometimes arteries become rigid. ANEURYSM may develop and widespread ATHEROMA (fat deposits) is apparent in the arterial linings. Such changes adversely affect the blood supply to body tissues and organs and so damage their functioning. Patients suffer STROKE (haemorrhage from or thrombosis in the arteries of the BRAIN) and heart attacks (coronary thrombosis
– see HEART, DISEASES OF). Those with hypertension may suffer damage to the retina of the EYE and to the OPTIC DISC. Indeed, the diagnosis of hypertension is sometimes made during a routine eye test, when the doctor or optician notices changes in the retinal arteries or optic disc. Kidney function is often affected, with patients excreting protein and excessive salt in their urine. Occasionally someone with persistent hypertension may suffer an acceleration of damage to the blood vessels – a condition described as ‘malignant’ hypertension, and one requiring urgent hospital treatment.
Hypertension is a potentially dangerous disease because it develops into a cycle of self-perpetuating damage. Faulty blood vessels lead to high blood pressure which in turn aggravates the damage in the vessels and thus in the tissues and organs they supply with blood; this further raises the affected individual’s blood pressure and the pathological cycle continues.... hypertension
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