High blood pressure does not mean excessive emotional tension, although emotional tension and stress can temporarily increase the blood pressure.

Normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called "pre-hypertension", and a blood pressure of 140/90 or above is considered high blood pressure. The systolic blood pressure, which is the top number, represents the pressure in the arteries as the heart contracts and pumps blood into the arteries. The diastolic pressure, which is the bottom number, represents the pressure in the arteries as the heart relaxes after the contraction. The diastolic pressure, therefore, reflects the minimum pressure to which the arteries are exposed.

An elevation of the systolic and/or diastolic blood pressure increases the risk of developing heart (cardiac) disease, kidney (renal) disease, hardening of the arteries (atherosclerosis or arteriosclerosis), eye damage, and stroke (brain damage). These complications of hypertension are often referred to as end-organ damage because damage to these organs is the end result of chronic (long duration) high blood pressure. Accordingly, the diagnosis of high blood pressure in an individual is important so that efforts can be made to normalise the blood pressure and, thereby, prevent the complications. Hypertension affects many adults in Ghana; it is clearly a major public health problem.

The blood pressure usually is measured with a small, portable instrument called a blood pressure cuff (sphygmomanometer). (Sphygmo in Greek means pulse, and a manometer measures pressure.) The blood pressure cuff consists of an air pump, a pressure gauge, and a rubber cuff. The instrument measures the blood pressure in units called millimeters of mercury (mm Hg).

Since blood pressure can be affected by several factors, it is important to standardise the environment with this in mind when blood pressure is determined. For at least one hour before measuring the BP one should avoid eating, strenuous exercise (which can lower blood pressure), smoking, and caffeine intake. Other stresses may alter the blood pressure and need to be considered when blood pressure is measured.

Two forms of high blood pressure have been described--essential (or primary) hypertension and secondary hypertension. Essential hypertension is a far more common condition and accounts for 95% of hypertension. The cause of essential hypertension is multifactorial, that is, there are several factors whose combined effects produce hypertension. In secondary hypertension, which accounts for 5% of hypertension, the high blood pressure is secondary to (caused by) a specific abnormality in one of the organs or systems of the body.

Essential hypertension affects a lot of people worldwide, yet its basic causes or underlying defects are not always known. Nevertheless, certain associations have been recognised in people with essential hypertension. For example, essential hypertension develops only in groups or societies that have a fairly high intake of salt, exceeding 5.8 grams daily. In fact, salt intake may be a particularly important factor in relation to essential hypertension in several situations. Thus, excess salt may be involved in the hypertension that is associated with advancing age, obesity, hereditary (genetic) susceptibility, and kidney failure (renal insufficiency).

Genetic factors are thought to play a prominent role in the development of essential hypertension. However, the genes for hypertension have not yet been identified. (Genes are tiny portions of chromosomes that produce the proteins that determine the characteristics of individuals.) The current research in this area is focused on the genetic factors that affect the renin-angiotensin-aldosterone system. This system helps to regulate blood pressure by controlling salt balance and the tone (state of elasticity) of the arteries.

Approximately, 30 % of cases of essential hypertension are attributable to genetic factors. For example, in the United States, the incidence of high blood pressure is greater among African-Americans than among Caucasians or Asians. Also, in individuals who have one or two parents with hypertension, high blood pressure is twice as common as in the general population. Rarely, certain unusual genetic disorders affecting the hormones of the adrenal glands may lead to hypertension. (These identified genetic disorders are actually considered secondary hypertension.)

The vast majority of patients with essential hypertension have in common a particular abnormality of the arteries. That is, they have an increased resistance (stiffness or lack of elasticity) in the tiny arteries that are most distant from the heart (peripheral arteries or arterioles). The arterioles supply oxygen-containing blood and nutrients to all of the tissues of the body.

The arterioles are connected by capillaries in the tissues to the venous system (or the veins), which returns the blood to the heart and lungs. Just what makes the peripheral arteries become stiff is not known. Yet, this increased peripheral arteriolar stiffness is present in those individuals whose essential hypertension is associated with genetic factors, obesity, lack of exercise, overuse of salt, and aging. Inflammation also may play a role in hypertension since a predictor of the development of hypertension is the presence of an elevated C reactive protein level (a blood test marker of inflammation) in some individuals.

As mentioned previously, 5% of people with hypertension have what is called secondary hypertension. This means that the hypertension in these individuals is secondary to (caused by) a specific disorder of a particular organ or blood vessel, such as the kidney, adrenal gland, or aortic artery.

Diseases of the kidneys can cause secondary hypertension. This type of secondary hypertension is called renal hypertension because it is caused by a problem in the kidneys. One important cause of renal hypertension is narrowing (stenosis) of the artery that supplies blood to the kidneys (renal artery). In younger individuals, usually women, the narrowing is caused by a thickening of the muscular wall of the arteries going to the kidney (fibromuscular hyperplasia). In older individuals, the narrowing generally is due to hard, fat-containing (atherosclerotic) plaques that are blocking the renal artery.

Renal hypertension is usually first suspected when high blood pressure is found in a young individual or a new onset of high blood pressure is discovered in an older person. Avoiding alcohol, smoking, coffee, taking fatty foods and doing a lot of exercise could help in reducing high blood pressure in people.

Alcohol

People who drink alcohol excessively (over two drinks per day) have a one and a half to two times increase in the prevalence of hypertension. The association between alcohol and high blood pressure is particularly noticeable when the alcohol intake exceeds five drinks per day. Moreover, the connection is a dose-related phenomenon. In other words, the more alcohol that is consumed, the stronger is the link with hypertension.

Smoking

Although smoking increases the risk of vascular complications (for example, heart disease and stroke) in people who already have hypertension, it is not associated with an increase in the development of hypertension. Nevertheless, smoking a cigarette can repeatedly produce an immediate, temporary rise in the blood pressure of 5 to10 mm Hg. Steady smokers however, actually may have a lower blood pressure than nonsmokers. The reason for this is that the nicotine in the cigarettes causes a decrease in appetite, which leads to weight loss. This, in turn, lowers the blood pressure.

Coffee

In one study, the caffeine consumed in five cups of coffee daily caused a mild increase in blood pressure in elderly people who already had hypertension, but not in those who had normal blood pressures. What's more, the combination of smoking and drinking coffee in persons with high blood pressure may increase the blood pressure more than coffee alone. Limiting caffeine intake and cigarette smoking in hypertensive individuals, therefore, may be of some benefit in controlling their high blood pressure.

Salt

The American Heart Association recommends that the consumption of dietary salt be less than six grams of salt per day in the general population and a lower level (for example, less than four grams) for people with hypertension. To achieve a diet containing less than four grams of salt, a person should not add salt to their food or cooking. Also, the amount of natural salt in the diet can be reasonably estimated from the labelling information provided with most purchased foods.

Obesity

Obesity is common among hypertensive patients, and its prevalence increases with age. In fact, obesity may be what determines the increased incidence of high blood pressure with age. Obesity can contribute to hypertension in several possible ways. For one thing, obesity leads to a greater output of blood because the heart has to pump out more blood to supply the excess tissue.

The increased cardiac output then can raise the blood pressure. For another thing, obese hypertensive individuals have a greater stiffness (resistance) in their peripheral arteries throughout the body. In addition, insulin resistance and the metabolic syndrome described previously occur more frequently in the obese. Finally, obesity may be associated with a tendency for the kidneys to retain salt.

Weight loss may help reverse problems related to obesity while also lowering the blood pressure. It has been estimated that the blood pressure can be decreased 0.32 mm Hg for every 1 kg (2.2 pounds) of weight lost down to ideal body weight for the individual.

Some obese people, especially if they are very obese, have a syndrome called sleep apnoea. This syndrome is characterised by the periodic interruption of normal breathing during sleep. Sleep apnoea may contribute to the development of hypertension in this subgroup of obese individuals. This happens because the repeated episodes of apnoea cause a lack of oxygen (hypoxia). The hypoxia then causes the adrenal gland to release adrenalin and related substances. Finally, the adrenalin and related substances cause a rise in the blood pressure.

Exercise

A regular exercise programme may help lower blood pressure over the long term. For example, activities such as jogging, bicycle riding, or swimming for 30 to 45 minutes daily may ultimately lower blood pressure by as much as 5 to15 mm Hg. Moreover, there appears to be a relationship between the amount of exercise and the degree to which the blood pressure is lowered. Thus, the more you exercise (up to a point), the more you lower the blood pressure.

The beneficial response of the blood pressure to exercise occurs only with aerobic (vigorous and sustained) exercise programmes. Therefore, any exercise programme must be recommended or approved by an individual's physician.