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Hypertension or high blood pressure, sometimes called arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is elevated. This requires the heart to work harder than normal to circulate blood through the blood vessels. Blood pressure is summarised by two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole). Normal blood pressure at rest is within the range of 100-140 mmHg systolic (top reading) and 60-90 mmHg diastolic (bottom reading). Highpotention is said to be present if blood presure is persistently at or above 140/90 mmHg.
Classification. Hypertension is classified as either primary (essential) hypertension or secondary hypertension; about 90–95% of cases are categorized as "primary hypertension" which means high blood pressure with no obvious underlying medical cause. The remaining 5–10% of cases (secondary hypertension) are caused by other conditions that affect the kidneys, arteries, heart or endocrine system.
Hypertension is rarely accompanied by any symptoms and signs except high blood pressure. People with high blood pressure report headaches (particularly at the back of the head and in the morning), as well as dizziness, fainting, vertigo, tinnitus, insomnia, nervousness, anxiety, altered vision etc. But these symptoms may be attributed to any condition, not only to hypertension. People may also demonstrate epistaxis and menorrhagia (in women).
On physical examination, hypertension may be suspected on the basis of the presence of hypertensive retinopathy and papilledema detected by examination of the optic fundus using ophthalmoscopy. Ophthalmoscopy findings may also give some indication as to how long a person has been hypertensive.
Severely elevated blood pressure (equal to or greater than a systolic 180 or diastolic of 110 — sometimes termed malignant or accelerated hypertension) is referred to as a "hypertensive crisis". People with blood pressures in this range may have no symptoms, but often report headaches and dizziness. Other symptoms accompanying a hypertensive crisis may include visual deterioration or breathlessness due to heart failure or a general feeling of malaise due to renal failure.
Risk factors. In almost all contemporary societies, blood pressure rises with aging and the risk of becoming hypertensive in later life is considerable. Hypertension results from a complex interaction of genes, lifestyle and environmental factors. Stress appears to play a minor role. The possible role of other factors such as caffeine consumption, and vitamin D deficiency are less clear cut. Insulin resistance, which is common in obesity and is a component of the metabolic syndrome, is also thought to contribute to hypertension. Recent studies have also implicated events in early life (for example low birth weight, maternal smoking and lack of breast feeding) as risk factors for adult essential hypertension, although the mechanisms linking these exposures to adult hypertension remain obscure.
Recommendations. Lifestyle factors that lower blood pressure include:
- reduced dietary salt intake,
- increased consumption of fruit and vegetables, and low fat products,
- regular physical activity (walking outdoors),
- maintaining normal body weight for adults (e.g. body mass index 20–25 kg/m2) and
- limited alcohol consumption.
Therapy. Several classes of medications, collectively referred to as antihypertensive drugs, are currently available for treating hypertension. They include: thiazide diuretic, calcium channel blockers (CCB), angiotensin converting enzyme inhibitors (ACE-I), beta-blockers, and alpha-blockers.
Complications. Hypertension is a major risk factor for stroke, myocardial infarction (heart attacks), heart failure, aneurysms of the arteries (e.g. aortic aneurysm), peripheral arterial disease and is a cause of chronic kidney disease (arterial nephrosclerosis which may be manifested by polyuria, nocturia, proteinuria, nitrogen retention etc.). Even moderate elevation of arterial blood pressure is associated with a shortened life expectancy.