Hypertension: Causes, Risk factors, Pathogenesis, Classification

Hypertension is a pathology of the cardiovascular apparatus that develops as a result of dysfunction of the higher centers of vascular regulation, neurohumoral and renal mechanisms and leading to arterial hypertension, functional and organic changes in the heart, central nervous system, and kidneys. Subjective manifestations of high blood pressure are headaches, tinnitus, palpitations, shortness of breath, pain in the heart, veils before the eyes, etc. Examination of hypertension includes monitoring of blood pressure, ECG, echocardiography, ultrasonography of the arteries of the kidneys and neck, urinalysis, and biochemical parameters blood. When the diagnosis is confirmed, the selection of drug therapy is made taking into account all risk factors.

General information about Hypertension

The leading manifestation of hypertension is persistently high blood pressure, that is, blood pressure that does not return to normal after a situational rise as a result of psycho-emotional or physical exertion, but decreases only after taking antihypertensive drugs. According to WHO recommendations, blood pressure is normal if it does not exceed 140/90 mm Hg. Art. Excess of the systolic index over 140-160 mm Hg. Art. and diastolic – over 90-95 mm Hg. Art., recorded in a state of rest with a double measurement during two medical examinations, is considered hypertension.

The prevalence of hypertension among women and men is approximately the same 10-20%, more often the disease develops after the age of 40, although hypertension is often found even in adolescents. Essential hypertension contributes to the more rapid development and severe course of atherosclerosis and the occurrence of life-threatening complications. Along with atherosclerosis, hypertension is one of the most common causes of premature mortality in the young working-age population.

Causes of Hypertension

Distinguish between primary ( essential ) arterial hypertension (or hypertension) and secondary (symptomatic) arterial hypertension. Primary arterial hypertension develops as an independent chronic disease and accounts for up to 90% of cases of arterial hypertension. In hypertension, high blood pressure is a consequence of an imbalance in the regulatory system of the body.

Symptomatic hypertension accounts for 5 to 10% of hypertension cases. Secondary hypertension is a manifestation of the underlying disease:

  • kidney diseases ( glomerulonephritis, pyelonephritis, tuberculosis, hydronephrosis, tumors, renal artery stenosis );
  • pathology of the thyroid gland ( thyrotoxicosis );
  • diseases of the adrenal glands ( pheochromocytoma, Itsenko-Cushing’s syndrome, primary hyperaldosteronism);
  • coarctation or atherosclerosis of the aorta, etc.

Risk factors of Hypertension

The leading role in the development of hypertensive Diseases is played by a violation of the regulatory activity of the higher parts of the central nervous system, which control the work of internal organs, including the cardiovascular system. The main factors contributing to the development of hypertension:

  1. Frequently repeated nervous overstrain, prolonged and intense excitement, frequent nervous shocks. Excessive stress associated with intellectual activity, work at night, the influence of vibration and noise contributes to the occurrence of hypertension.
  2. Increased salt intake, which can cause arterial spasm and fluid retention. It has been proven that the consumption of> 5 g of salt per day significantly increases the risk of developing hypertension, especially if there is a hereditary predisposition.
  3. Heredity, aggravated by hypertension, plays an essential role in its development in close relatives (parents, sisters, brothers). The likelihood of developing hypertension increases significantly in the presence of hypertension in 2 or more close relatives.
  4. Arterial hypertension in combination with diseases of the adrenal glands, thyroid gland, kidneys, diabetes mellitus, atherosclerosis, obesity, chronic infections ( tonsillitis ) contribute to the development of hypertension and mutually support each other.
  5. In women, the risk of developing hypertension increases in menopause due to hormonal imbalance and exacerbation of emotional and nervous reactions. 60% of women fall ill with hypertension during menopause.
  6. Alcoholism and smoking, an irrational diet, excess weight, physical inactivity, and an unfavorable environment are extremely favorable to the development of hypertension.
  7. The age factor and gender determine the increased risk of developing hypertension in men. At the age of 20-30, hypertension develops in 9.4% of men, after 40 years – in 35%, and after 60-65 years – already in 50%. In the age group under 40, hypertension is more common in men; in the older age group, the ratio changes in favor of women. This is due to a higher rate of male premature mortality in middle age from complications of hypertension, as well as menopausal changes in the female body. At present, hypertensive Disease is more and more often detected in people at a young and mature age.

 

Pathogenesis of Hypertension

The pathogenesis of hypertensive Diseases is based on an increase in the volume of cardiac output and resistance of the peripheral vascular bed. In response to the effect of a stress factor, disturbances in the regulation of the tone of peripheral vessels by the higher centers of the brain (hypothalamus and medulla oblongata) occur. There is a spasm of arterioles in the periphery, including the renal, which causes the formation of dyskinetic and dyscirculatory syndromes. The secretion of neurohormones of the renin-angiotensin-aldosterone system increases. Aldosterone, involved in mineral metabolism, causes water and sodium retention in the vascular bed, which further increases the volume of blood circulating in the blood vessels and increases blood pressure.

With arterial hypertension, blood viscosity increases, which causes a decrease in the rate of blood flow and metabolic processes in tissues. Inert walls of blood vessels thicken their lumen narrows, which fixes a high level of total peripheral vascular resistance and makes arterial hypertension irreversible. Subsequently, as a result of the increased permeability and plasma impregnation of the vascular walls, ellastofibrosis, and arteriolosclerosis develop, which ultimately leads to secondary changes in the tissues of organs: myocardial sclerosis, hypertensive encephalopathy, primary nephroangiosclerosis.

The degree of damage to various organs in hypertensive diseases may be different, therefore, there are several clinical and anatomical variants of hypertension with a predominant lesion of the vessels of the kidneys, heart, and brain.

Classification of Hypertension

The hypertensive disease is classified according to a number of signs: the reasons for the rise in blood pressure, damage to target organs, according to the level of blood pressure, along the course, etc. On the etiological principle, they distinguish essential (primary) and secondary (symptomatic) arterial hypertension. By the nature of the course, hypertension can have a benign (slowly progressive) or malignant (rapidly progressive) course.

The greatest practical value is the level and stability of blood pressure. Depending on the level, there are:

  • Optimal blood pressure is <120/80 mm Hg. Art.
  • Normal blood pressure is 120-129 / 84 mm Hg. Art.
  • Borderline normal blood pressure – 130-139 / 85-89 mm Hg. Art.
  • Arterial hypertension of the I degree – 140-159 / 90-99 mm Hg. Art.
  • Arterial hypertension II degree – 160-179 / 100-109 mm Hg. Art.
  • Arterial hypertension of the III degree – more than 180/110 mm Hg. Art.

According to the level of diastolic blood pressure, variants of hypertension are distinguished:

  • Mild course – diastolic blood pressure <100 mm Hg. Art.
  • Moderate course – diastolic blood pressure from 100 to 115 mm Hg. Art.
  • Severe course – diastolic blood pressure> 115 mm Hg. Art.

Benign, slowly progressing hypertension, depending on the damage to the target organs and the development of associated (concomitant) conditions, goes through three stages:

  1. Stage I (mild and moderate hypertension) – blood pressure is unstable, fluctuating during the day from 140/90 to 160-179 / 95-114 mm Hg. Art., hypertensive crises occur rarely, are mild. There are no signs of organic damage to the central nervous system and internal organs.
  2. Stage II (severe hypertension) – BP in the range of 180-209 / 115-124 mm Hg. Art., hypertensive crises are typical. Objectively (with physical, laboratory research, echocardiography, electrocardiography, radiography), narrowing of the retinal arteries, microalbuminuria, increased creatinine in blood plasma, left ventricular hypertrophy, transient cerebral ischemia are recorded.
  3. Stage III (very severe hypertension) – BP from 200-300 / 125-129 mm Hg. Art. and higher, severe hypertensive crises often develop. The damaging effect of hypertension causes the phenomena of hypertensive encephalopathy, left ventricular failure, the development of cerebral vascular thrombosis, hemorrhages and edema of the optic nerve, dissecting vascular aneurysms, nephroangiosclerosis, renal failure, etc.

 

Symptoms of hypertension

The options for the course of hypertension are varied and depend on the level of increase in blood pressure and on the involvement of target organs. In the early stages, hypertension is characterized by neurotic disorders: dizziness, transient headaches (more often in the back of the head) and heaviness in the head, tinnitus, throbbing in the head, sleep disturbances, fatigue, lethargy, feeling of weakness, palpitations, nausea.

In the future, shortness of breath joins with fast walking, running, exertion, climbing stairs. Blood pressure is consistently above 140-160 / 90-95 mm Hg. (or 19-21 / 12 hPa). Sweating, facial flushing, chill-like tremors, numbness of the toes and hands are noted, and dull, prolonged pain in the region of the heart is typical. With fluid retention, there is swelling of the hands (“ring symptom” – it is difficult to remove the ring from the finger), face, puffiness of the eyelids, stiffness.

In patients with essential hypertension, there is a veil, flashing of flies and lightning before the eyes, which is associated with vasospasm in the retina; there is a progressive decrease in vision, hemorrhages in the retina can cause complete loss of vision.

Complications

With a prolonged or malignant course of hypertension, chronic damage to the vessels of target organs develops the brain, kidneys, heart, eyes. Instability of blood circulation in these organs against the background of persistently elevated blood pressure can cause the development of angina pectoris , myocardial infarction , hemorrhagic or ischemic stroke , cardiac asthma, pulmonary edema, dissecting aortic aneurysms, retinal detachment, uremia. The development of acute emergency conditions against the background of hypertension requires a decrease in blood pressure in the first minutes and hours, since it can lead to the death of the patient.

The course of hypertensive diseases is often complicated by hypertensive crises – periodic short-term rises in blood pressure. The development of crises may be preceded by emotional or physical overstrain, stress, a change in meteorological conditions, etc. In a hypertensive crisis, a sudden rise in blood pressure is observed, which can last for several hours or days and be accompanied by dizziness, sharp headaches, fever, palpitations, vomiting, cardialgia , visual impairment.

Patients during a hypertensive crisis are scared, excited or inhibited, drowsy; in severe crisis, they can lose consciousness. Against the background of a hypertensive crisis and existing organic vascular changes, myocardial infarction, acute cerebrovascular accidents, acute left ventricular failure can often occur .

Diagnostics

Examination of patients with suspected essential hypertension aims to confirm a stable increase in blood pressure, exclude secondary arterial hypertension, identify the presence and extent of damage to target organs, assess the stage of arterial hypertension and the risk of complications. When collecting anamnesis, special attention is paid to the patient’s susceptibility to risk factors for hypertension, complaints, the level of increased blood pressure, the presence of hypertensive crises and concomitant diseases.

Dynamic blood pressure measurement is informative for determining the presence and degree of hypertension. To obtain reliable indicators of the level of blood pressure, the following conditions must be observed:

  • The measurement of blood pressure is carried out in a comfortable, calm environment, after 5-10 minutes of patient adaptation. It is recommended to exclude smoking, exercise, food intake, tea and coffee, the use of nasal and eye drops (sympathomimetics) 1 hour before the measurement.
  • The position of the patient is sitting, standing or lying down, the hand is at the same level with the heart. The cuff is placed on the shoulder, 2.5 cm above the elbow fossa.
  • At the patient’s first visit, BP is measured on both arms, with repeated measurements after a 1–2 minute interval. If the BP asymmetry is> 5 mm Hg, subsequent measurements should be performed on the arm with higher readings. In other cases, BP is usually measured on the “non-working” arm.

If the blood pressure indicators during repeated measurements differ among themselves, then the arithmetic mean is taken as the true one (excluding the minimum and maximum blood pressure indicators). In hypertensive Diseases, self-monitoring of blood pressure at home is extremely important.

Laboratory tests include clinical blood and urine tests, biochemical determination of the level of potassium, glucose, creatinine, total blood cholesterol, triglycerides, urine analysis according to Zimnitsky and Nechiporenko, Reberg’s test.

On electrocardiography in 12 leads with hypertension, left ventricular hypertrophy is determined. ECG data are verified by echocardiography. Ophthalmoscopy with fundus examination reveals the degree of hypertensive angioretinopathy. By conducting an ultrasound of the heart, an increase in the left heart is determined. To determine the lesion of target organs , ultrasound of the abdominal cavity , EEG , urography , aortography , CT of the kidneys and adrenal glands are performed .

Treatment

it is important not only to lower blood pressure, but also to correct and reduce the risk of complications as much as possible. It is impossible to completely cure hypertension, but it is quite possible to stop its development and reduce the frequency of crises.

Essential hypertension requires the joint efforts of the patient and the doctor to achieve a common goal. At any stage of hypertensive diseases, it is necessary:

  • Follow a diet with increased consumption of potassium and magnesium, limiting the consumption of table salt;
  • Stop or drastically restrict alcohol and smoking;
  • Get rid of excess weight;
  • To increase physical activity: it is useful to go in for swimming, physiotherapy exercises , take walking walks;
  • Systematically and for a long time to take the prescribed drugs under the control of blood pressure and dynamic observation of a cardiologist .

antihypertensive drugs are prescribed that inhibit vasomotor activity and inhibit the synthesis of norepinephrine, diuretics, β-blockers, antiplatelet agents, hypolipidemic and hypoglycemic, sedatives. The selection of drug therapy is carried out strictly individually, taking into account the entire spectrum of risk factors, blood pressure levels, the presence of concomitant diseases and damage to target organs.

The criteria for the effectiveness of hypertension treatment is the achievement of:

  • short-term goals: maximum decrease in blood pressure to a level of good tolerance;
  • medium-term goals: preventing the development or progression of changes on the part of target organs;
  • long-term goals: prevention of cardiovascular and other complications and prolongation of the patient’s life.

 

Forecast

Long-term consequences are determined by the stage and nature (benign or malignant) of the disease. Severe course, rapid progression of hypertensive diseases, stage III hypertension with severe vascular damage significantly increases the frequency of vascular complications and worsens the prognosis.

With essential hypertension, the risk of myocardial infarction, stroke, heart failure and premature death is extremely high. Hypertension is unfavorable in people who fall ill at a young age. Early, systematic therapy and blood pressure control can slow the progression of hypertension.

Prevention

For the primary prevention of hypertensive diseases, it is necessary to exclude the existing risk factors. Moderate physical activity, low-salt and hypo cholesterol diet, psychological relief, rejection of bad habits are useful. It is important to early detection of hypertesion by monitoring and self-monitoring blood pressure, dispensary registration of patients, adherence to individual antihypertensive therapy, and maintaining optimal blood pressure.