Hypertension, results in the resting arterial blood pressure values being higher than normal (i.e. above 140 mmHg systolic and above 90 mmHg diastolic). Hypertension appears very rarely in childhood, but its incidence starts rising soon after puberty. Studies show that 40% of adults have blood pressure values exceeding the normal values. Men are more commonly affected than women, especially due to a larger number of risk factors (smoking, alcoholism) among men. There are also individual racial differences with the black race much more affected than the white race.
Two types of hypertension
Hypertension is divided into two large groups based on the cause. The most common is the primary or essential hypertension where no detailed cause of disease can be found. Most people (94%) are affected by this type. The development of essential hypertension is based on a large number of factors including the age, sex, race, genetic factors as well as environmental factors (diet, especially the amount of salt consumed), occupation and personal habits (smoking, alcohol consumption and exercise). Furthermore, diabetes mellitus is a very important risk factor.
The second group includes hypertension types with a known cause—i.e. secondary hypertension. A typical example is hypertension secondary to kidney disease and abnormal function of the renal hormones which causes a disturbance in electrolyte regulation, mainly potassium and sodium, and water retention, causing an increase in blood pressure. Hypertension can also appear as a consequence of an adrenal gland medullary tumour which is characterised by an excessive secretion of sympathomimetic hormones that constrict blood vessels and thus raise blood pressure. Many other rarer causes are possible. It is important to know that a cause can be determined only in 6% of all hypertension cases.
Possible risks of hypertension
There are many consequences to hypertension, the most dangerous ones affecting the heart. It can lead to cardiac failure or myocardial infarction. The nervous system is also afflicted resulting in visual disturbances, severe headaches and a stroke in the worst case scenario. In addition, kidneys are also often affected. High blood pressure injures the kidney tissue consequently affecting its function. A chain of events is triggered similar to the one in the case of hypertension secondary to kidney disease. Kidney damage additionally increases blood pressure which in turn damages kidneys, fuelling a vicious cycle whose end result can be kidney failure if hypertension is not diagnosed and treated in due course.
Lifestyle is the most essential element in the prevention of hypertension. It is especially critical in people with risk factors that cannot be modified, such as family history of hypertension, age, race as well as gender. We can do a lot on our own to facilitate blood pressure normalisation.
The measures to be taken are the following:
It is important to maintain a normal body weight,
The consumption of dietary salt should be below 2.3 g/day which roughly corresponds to one table-spoon,
Regular physical activity, for instance at least 30 minutes of fast walking on most days of the week,
Limit alcohol consumption; recommended are approx. 2 glasses/day for men and 1 glass/day for women,
Stress reduction which can be attained by engaging in various hobbies, taking strolls, etc.,
Adequate therapy of other chronic diseases such as diabetes mellitus, increased cholesterol level, kidney disease, etc.
Much can be accomplished already with minor lifestyle changes. In the cases where this is not enough, however, your physician shall prescribe anti-hypertensive medication. The choice of medication depends on your blood pressure as well as possible diseases (diabetes mellitus, chronic kidney failure, etc.).
The main categories of medication used are:
Diuretics – their target organ are the kidneys where they act to facilitate elimination of excess salt and water. In elderly people, a special type of thiazide diuretics (indapamide) is especially useful. They successfully lower the blood pressure and reduce the chance of a stroke and heart failure.
Beta blockers – they reduce the load on the heart and dilate the vessels; the heart rate is slowed down and the force of contraction is diminished.
Inhibitors of angiotensin convertase (ACE inhibitors) – inhibit the formation of angiotensin II which causes vessels to become more narrow (i.e. vasoconstriction), inhibit the formation of endothelins (vasoconstrictors), reduce the action of the sympathetic nervous system and stimulate the breakdown of bradykinin (also a vasoconstrictor). They are essential for treating hypertension in people with heart and/or kidney failure as well as in people with coronary vessel disease.
Inhibitors of angiotensin II receptors – they inhibit the action of angiotensin II and are an important class of drugs used in patients with heart or kidney failure.
Calcium channel blockers – facilitate the vessel's smooth muscle relaxation
Renin inhibitors – inhibit the formation of renin which is a substance that is formed in the kidneys and triggers a series of reactions that result in blood pressure increase.
In most cases, a single drug or a combination therapy with the above-mentioned medications suffices to control the blood pressure. At times, however, therapy does not yield the desired results.
In such cases, the following can be employed:
Alpha blockers – act to reduce the nerve impulses to the vessel walls thereby preventing vasoconstriction.
Vasodilators – acts directly on the smooth muscles in the vessels and prevent their contraction.
Centrally-acting drugs – prevent the brain from sending a message to the nervous system to increase the heart rate and constrict the vessels.
In many cases, the physician decides to prescribe the supplemental low-dose aspirin therapy in addition to the specific therapy in order to prevent the hypertension-associated cardiac complications.