1. What is hypertension?

Hypertension or HTA is a permanent elevation of blood pressure in the arteries above the normal figures, eg when the blood pressure is greater than or equal to 140/90 millimeters of mercury (mmHg).

In the world population, WHO estimated that a quarter of the adult population suffers from hypertension, but epidemiological data are underestimated. The incidence of the disease is growing rapidly in sub-Saharan Africa .

The prevalence of hypertension increases with age and the disease is generally more common among men than among women.
Hypertension is a major risk factor for cardiovascular disease which are the primary cause of death in Western countries (coronary heart diseases, stroke, heart failure,... ).

2. Which are the causes of hypertension ?     

  • At almost 90% of hypertensive patients, there is no specific cause. Then, we speak about essential hypertension, idiopathic or primary. It is probably the consequence of several factors that lead to physiological changes affecting the kidneys, heart and blood vessels (atherosclerosis), which combine together to elevate the blood pressure.
  • From 5 to 10% of patients with hypertension, one cause can be identified: we speak about secondary hypertension whose the major causes are kidney disease (renal artery stenosis), some hormonal disorders (pheochromocytoma, hyperthyroidism, etc.) or various substances (cocaine, licorice, etc).

Obesity, smoking, lack of exercise, excessive consumption of alcohol or salt may also play a role in the onset of hypertension, particularly among susceptible people.

Genetic predisposition may also play a role in the genesis of hypertension, so that there are families where hypertension is significantly higher than in the ordinary population.
Stress tends to increase blood pressure, but usually temporarily. Once the situation responsible for the stress removed, blood pressure returns to normal in most cases. The phenomenon called "hypertension of the white coat" is a great example.

3. Which are the symptoms of hypertension ?     

Symptoms of hypertension are usually aspecific.

Hypertensive patients don't feel anything if their blood pressure remains mild and stable over time.
Only in hard hypertension, patient may present symptoms such as headache (often in the morning), nausea or vomiting, visual problems such as a "feeling of flying flies" buzzing ear, dizziness. The patient may also present a bleeding nose.

In fact, the only way to know if you are hypertensive is to control your blood pressure by a doctor with a device called a sphygmomanometer which measures the two representative figures of blood pressure.

The maximum value is the systolic blood pressure: it is recorded when the heart contracts (systole) to project to blood vessels throughout the body.
The minimum value is the diastolic blood pressure: it is when the heart is relaxed between beats (diastole), which allows it to fill again with blood, for the next contraction.

It is called hypertension when the systolic blood pressure greater than or equal to 140 millimeters of mercury (mmHg) and / or diastolic is greater than or equal to 90 mmHg. When both values are high, hypertension is known systolo-diastolic.

When only the systolic blood pressure is high, hypertension is isolated systolic (frequent in the elderly).
The diagnosis of hypertension is established when high values are observed several times at rest, during various consultations. This data is very important because blood pressure varies widely from one point to another.

4. Classification of hypertension

This table shows the different stages of severity of hypertension according to WHO guidelines (1999) based on blood pressure values expressed in millimeters of mercury (mmHg).
Category Systolic Diastolic
Optimal blood pressure < 120 < 80
Normal blood pressure < 130 < 85
High-normal blood pressure 130-139 85-89
Mild hypertension, stage 1 140-159 90-99
Moderate hypertension, stage 2 160-179 100-109
Severe hypertension, stage 3 >= 180 >= 110

5. Which possible complications for hypertension?      

High blood pressure increases mainly the risk of stroke, heart failure, myocardial infarction and renal failure.
The brain, heart and kidneys which are also vital organs are preferentially target organs affected by the complications of hypertension.

The Cardiac consequences of hypertension is detected early by electrocardiography and echocardiography, which is a test using ultrasound to visualize both the wall and cardiac chambers. The achievement is a hypertrophy of the lining of the heart, which is a consequence of the additional work done by the heart to ensure the distribution of blood to the organs in spite of high blood pressure. Without treatment, the heart muscle gradually depleted, leading to heart failure.

The detection of renal disease (nephropathy) is done by finding albumin in urine and determining the rate of creatinin in the blood.
The retina is an excellent place to observe the effects of hypertension on small arteries. An examination of the background eye made with an ophthalmoscope, allow to see the inner surface of the posterior of the eye where is the retina. Changes in blood vessels of the retina is a reflection of the achievement of other vessels of the body, particularly the kidneys. The appreciation of the importance of retinal damage (retinopathy) is used to correlate with the severity of hypertension.

6. Which treatment for hypertension?     

Despite the high prevalence of hypertension and its complications, adequate blood pressure control (defined by a blood pressure below 140/90 mm Hg) is unfortunately achieved in 34% of patients.

Secondary hypertension may well be cured by treatment of the defect responsible for the condition or the removal of the causative agent.

For essential hypertension or primary, the problem is different since there is no single cause clearly identified. The goal of treatment is to normalize the blood pressure profiles to avoid the complications of hypertension.

The first steps are likely dietary. They are to restore a healthy lifestyle through a proper weight loss in overweight, a smoking cessation, moderation of alcohol consumption and salt and practice of regular physical activity. Diabetics and those with too much cholesterol should have a specific diet that will participate in the reduction of cardiovascular risk. In some cases, these measures may suffice to normalize blood pressure lasting.

In case of inadequacy of these dietary guidelines on blood pressure control, the introduction of medical treatment will be indicated and will be conducted by the physician taking into account the profile of cardiovascular risk, factors of co-morbidity and degree of achieving the target organ.

The goal of treatment is to achieve blood pressure values below 140/90 mmHg. In case of diabetes, blood pressure will be reduced to below 130/80 mmHg.
Of course, it will be harder to bring blood pressure below the recommended values when the initial level was high.

In many cases, control of hypertension will lead to use not one but several drugs.

The main classes of drugs used to control high blood pressure are the thiazide diuretics, beta-blockers, calcium antagonists, inhibitors of angiotensin converting enzyme antagonists and angiotensin 2.
At the start of treatment anti-hypertensive drug, the patient must be convinced of the interest to treat hypertension. His adherence to treatment is very important to achieve balance and blood pressure and put all the chances for his side to avoid the complications of the disease.
An unintended treatment interruption could lead to a rebound effect with worsening of hypertension.

7. Conclusion     

In conclusion, hypertension is a serious disease whose clinical presentation is insidious and whose long-term consequences are disastrous from the socio-economic status.
The prognosis of hypertensive patients depends on early diagnosis and effectiveness of the treatment of the condition .
8. Références     

1. The Joint National Committee on Prevention
Detection, Evaluation and Treatment of High Blood Pressure. The Sixth report
Arch Intern Med 1997; 157 : 2413-2446.
2. Guidelines subcommittee 1999.
World Health Organization International Society of Hypertension Guidelines for the
Management of Hypertension
J Hypertens 1999; 17 :151-183.
3. Vasan R, Larson M, Leip E, et al.
Assessment of frequency of progression to hypertension in non-hypertensive
participants in the Framingham Heart Study : a cohort study
Lancet 2001; 358 : 1682-1686.
4. Vasan R, Larson M, Leip E, et al.
Impact of high-normal blood pressure on the risk of cardiovascular disease
N Engl J Med 2000; 345 : 1291-1297.
5. The Heart Outcomes Prevention Evaluation (HOPE) Study Investigators
Effects of an angiotensin-c converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients
N Engl J Med 2000; 342 : 145-153.
6. PROGRESS Collaborative Group
Randomised trial of a perindopril-based blood-pressure-lowering regimen
among 6105 individuals with previous stroke or transient ischaemic attack.
Lancet 2001 ; 358  : 1033-1041.