Hypertension, also known as high or raised blood pressure, is a condition in which the blood vessels have persistently raised pressure. Blood is carried from the heart to all parts of the body in the vessels. Each time the heart beats, it pumps blood into the vessels. Blood pressure is created by the force of blood pushing against the walls of blood vessels (arteries) as it is pumped by the heart. The higher the pressure in blood vessels the harder the heart has to work in order to pump blood. If left uncontrolled, hypertension can lead to a heart attack, an enlargement of the heart and eventually heart failure. Blood vessels may develop bulges (aneurysms) and weak spots due to high pressure, making them more likely to clog and burst. The pressure in the blood vessels can also cause blood to leak out into the brain. This can cause a stroke. Hypertension can also lead to kidney failure, blindness, rupture of blood vessels and cognitive impairment.

Blood pressure is measured in millimeters of mercury (mm Hg) and is recorded as two numbers usually written one above the other. The upper number is the systolic blood pressure - the highest pressure in blood vessels when the heart contracts, or beats. The lower number is the diastolic blood pressure - the lowest pressure in blood vessels when the heart muscle relaxes. Normal adult blood pressure is defined as a systolic blood pressure of 120 mm Hg and a diastolic blood pressure of 80 mm Hg.

Hypertension is defined as a systolic blood pressure equal to or above 140 mm Hg and/or diastolic blood pressure equal to or above 90 mm Hg.

More than 1 in 5 adults worldwide have raised blood pressure – a condition that causes around half of all deaths from stroke and heart disease. Complications from hypertension account for 9.4 million deaths worldwide every year.

In nearly all high-income countries, widespread diagnosis and treatment with low-cost medication have led to a significant drop in the proportion of people with raised blood pressure as well as the average blood pressure across populations. This has contributed to a reduction in deaths from heart disease. For example, the prevalence of raised blood pressure in the WHO region of the Americas in 2014 was 18%, as compared to 31% in 1980.

In contrast, low-income countries have the highest prevalence of raised blood pressure. In the WHO African region, more than 30% of adults in many countries are estimated to have high blood pressure. This proportion is increasing and the average blood pressure levels in this region are much higher than global averages.

Many people with high blood pressure in developing countries are not aware of their disease. Those who are diagnosed may not have access to treatment and may not be able to successfully control their illness over the long term. It contributes to the burden of heart disease, stroke and kidney failure and premature mortality and disability.

Detection, treatment and control of hypertension is an important health priority worldwide.

Hypertension is divided into primary (essential) and secondary hypertension.

Primary or essential hypertension-When the underlying cause cannot be determined, this type of high blood pressure is called "essential hypertension”. It accounts for 90-95% of adult cases of hypertension. It has been linked to certain risk factors. It may develop as a result of environmental or genetic causes. Obesity, diabetes, and heart disease also have genetic components and contribute to hypertension.

Secondary hypertension-When a direct cause for high blood pressure can be identified, the condition is described as secondary hypertension. About 2-10% of high blood pressure cases are due to an underlying condition or cause such as-

Renal parenchymal diseases (2.5-6%),
Vascular causes (.2-4%),
Endocrine causes (1-2%)
 exogenous(administration of steroids, oral contraceptive use),
endogenous( primary hyperaldosteronism, cushing syndrome, pheochromocytoma,  congenital adrenal hyperplasia),
drugs and toxins (alcohol, cocaine, non-steroidal anti-inflammatory drugs(NSAID), nicotine, decongestant containing ephedrine, herbal remedies containing licorice or ephedrine).
 Other causes include pregnancy induced hypertension, Obstructive sleep apnea.

Risk factors for developing high blood pressure are-

Non-modifiable risk factors-

 Family history-High blood pressure can run in a family.
 Advanced age-Risk of high blood pressure increases with age.
 Gender- High blood pressure is more common in young and middle aged men, while higher proportion of women suffer from hypertension late in life due to post-menopausal changes.
Modifiable risk factors-

Lack of physical activity.
Poor diet- consumption of food containing too much salt and fat, and not eating enough fruits and vegetables.
 Overweight and obesity.
Heavy and too much consumption of alcohol.
 Possible contributing factors- poor stress management, smoking and second hand smoke, sleep apnea.
 Pre-hypertension (blood pressure slightly higher than normal) increases the risk of developing hypertension in the future.
Diabetes mellitus-About 60% of people who have diabetes also have high blood pressure.

Most hypertensive people have no symptoms at all; this is why it is known as the “silent killer”.

Sometimes hypertension causes symptoms such as headache, shortness of breath, dizziness, chest pain, palpitations of the heart and nose bleeds. It can be dangerous to ignore such symptoms, but neither can they be relied upon to signify hypertension.

Hypertension is a serious warning sign that significant lifestyle changes are required.

All adults should have their blood pressure checked routinely, If blood pressure is high, they need the advice of a health worker.

For some people, lifestyle changes are sufficient to control blood pressure. For others, these changes are insufficient and they need prescription medication to control blood pressure.

Lifestyle measures:

Salt restriction - reducing salt intake to less than 5 g of salt per day(typical salt intake is 9 -12 g per day)
 Limit intake of alcohol.
 High consumption of vegetables and fruits and low-fat diet.
Reducing weight and maintaining it.
 Regular physical exercise - hypertensive patients should participate in at least 30 min of moderate-intensity dynamic aerobic exercise (walking, jogging, cycling or swimming) on 5 to 7 days a week.
Stop Smoking and use of other tobacco products.
Dietary Approaches to Stop Hypertension (DASH)-The DASH eating plan requires no special foods and instead provides daily and weekly nutritional goals. This plan recommends:

 Eating vegetables, fruits, and whole grains.
 Including fat-free or low-fat dairy products, fish, poultry, beans, nuts, and vegetable oil
Limiting foods that are high in saturated fat, such as fatty meats, full-fat dairy products, and tropical oils such as coconut, palm kernel, and palm oils.
 Limiting sugar-sweetened beverages and sweets.
When following the DASH eating plan, it is important to choose foods that are:

 Low in saturated and trans fats
 Rich in potassium, calcium, magnesium, fiber, and protein
 Lower in sodium
Antihypertensive Medicines- Antihypertensive drugs (drugs lowering the BP) work in several ways, such as removing excess salt and fluid from the body, slowing the heartbeat or relaxing and widening the blood vessels. Medicines to lower blood pressure include:

Diuretics (Water or Fluid Pills): Flush excess sodium from the body, which reduces the amount of fluid in blood and helps to lower your blood pressure.
Beta Blockers: Help heart to beat slower and with less force. As a result, heart pumps less blood through blood vessels, which can help to lower blood pressure.
Angiotensin-Converting Enzyme (ACE) Inhibitors: Angiotensin-II is a hormone that narrows blood vessels, increasing blood pressure. ACE converts Angiotensin I to Angiotensin II. ACE inhibitors block this process, which stops the production of Angiotensin II, lowering blood pressure.
Angiotensin II Receptor Blockers (ARBs): Block angiotensin II hormone from binding with receptors in the blood vessels. When angiotensin II is blocked, the blood vessels do not constrict or narrow, which can lower your blood pressure.
Calcium Channel Blockers: Keep calcium from entering the muscle cells of heart and blood vessels. This allows blood vessels to relax, which can lower blood pressure.
Alpha Blockers: Reduce nerve impulses that tighten blood vessels. This allows blood to flow more freely, causing blood pressure to go down.
Alpha-Beta Blockers: Reduce nerve impulses and also slow the heartbeat. As a result, blood pressure goes down.
Central Acting Agents: Act in the brain to decrease nerve signals that narrow blood vessels, which can lower blood pressure.
Vasodilators: Relax the muscles in blood vessel walls, which can lower blood pressure.

Primary prevention-

Everyone can take five concrete steps to minimize the chances of developing high blood pressure and its adverse consequences. This is termed as primary prevention. It includes-

1. Healthy diet:

promoting a healthy lifestyle with emphasis on proper nutrition for infants and young people;
reducing salt intake to less than 5 g of salt per day (just under a teaspoon);
eating five servings of fruit and vegetables a day;
reducing saturated and total fat intake.
2. Avoiding harmful use of alcohol i.e. limit intake to no more than one standard drink a day

3. Physical activity:

Regular physical activity and promotion of physical activity for children and young people (at least 30 minutes a day five times a week).
Maintaining a normal body weight: every 5 kg of excess weight lost can reduce systolic blood pressure by 2 to 10 points.
4. Stopping tobacco use and exposure to tobacco products.

5. Managing stress in healthy ways such as through meditation, appropriate physical exercise, and positive social contact.

Secondary prevention-The goal of secondary prevention is to detect and control high blood pressure in affected individual, thereby reducing the risk of complications.

Early case detection by regular checks up of blood pressure- If hypertension is detected early it is possible to minimize the risk of heart attack, heart failure, stroke and kidney failure. Self-care can facilitate early detection of hypertension, adherence to medication and healthy behaviours, better control and awareness of the importance of seeking medical advice when necessary. Self-care is important for all, but it is particularly so for people who have limited access to health services due to geographic, physical or economic reasons.
Treatment-The aim of treatment should be to obtain a blood pressure below 140/90 mmHg, and ideally a blood pressure of 120/80 mmHg.
Patient compliance (in terms of taking medicine, following diets and other life style changes) should be improved through education of patients, families and the community.

All adults should know their blood pressure levels. There are different types of devices that are used to measure blood pressure. These are electronic, mercury and aneroid devices.

 WHO recommends the use of affordable and reliable electronic devices that have the option to select manual readings. Semi-automatic devices enable manual readings to be taken when batteries run down.
 It is recommended by WHO that mercury devices should be phased out in favour of electronic devices (as mercury is a toxic material).
Aneroid devices such as sphygmomanometers should be used only if they are calibrated every six months and users should be trained in measuring blood pressure using such devices.
Blood pressure measurements need to be recorded for several days before a diagnosis of hypertension can be made. Blood pressure is recorded twice daily, ideally in the morning and evening. Two consecutive measurements are taken, at least a minute apart and with the person seated. Measurements taken on the first day are discarded and the average value of all the remaining measurements is taken to confirm a diagnosis of hypertension.

Routine laboratory tests are also recommended before initiating therapy. These include an electrocardiogram; urine analysis; blood glucose and hematocrit; serum potassium, creatinine (or the corresponding estimated glomerular filtration rate [GFR]), calcium; and a lipid profile, after 9 to12 hour fast, that includes high-density lipoprotein cholesterol and low-density lipoprotein cholesterol, and triglycerides.

Digital blood pressure measurement machines can be used outside clinic settings. Self-monitoring of blood pressure is recommended for the management of hypertension in patients where measurement devices are affordable and who have limited access to health services due to geographic, physical or economic reasons.

When blood pressure stays high over long time, it can damage the different organs of the body and causes complications. Some common complications include:

 Heart: left ventricular hypertrophy, angina/previous myocardial infarction, and heart failure
Brain: stroke or transient ischemic attack, dementia
Chronic kidney disease
 Peripheral arterial disease, aneurysms
Retinopathy
 Cognitive changes
If hypertension is detected early, with adherence to medication and healthy behaviours it is possible to minimize the risk of heart attack, heart failure, stroke and kidney failure.

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