hypertension

More about Hypertension:
Causes and symptoms
Diagnosis
Treatment
Prognosis
Prevention
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Definition

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers blood pressure less than 140 over 90 normal for adults.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age six and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It is also more common in African-Americans than in white Americans.

Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications can be avoided by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

arteriosclerosis, also called atherosclerosis
heart attack
stroke
enlarged heart
kidney damage

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots can also get trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant are needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.

— Toni Rizzo

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Dictionary: hy·per·ten·sion (hī'pər-tĕn'shən) pronunciation

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Arterial disease in which chronic high blood pressure is the primary symptom.
Abnormally elevated blood pressure.

Sci-Tech Encyclopedia: Hypertension

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High blood pressure. Blood pressure is expressed in two numbers: the higher number is the systolic blood pressure, which is the pressure exerted by the blood against the walls of the blood vessels while the heart is contracting. The lower number is the diastolic blood pressure, which is the residual pressure that exists between heart contractions, or while the heart is relaxing. Normal blood pressure provides sufficient blood flow to the vital organs, including the brain, heart, kidneys, intestine, and skeletal muscle.

It is not entirely accurate to think of high blood pressure as a distinct disease; high blood pressure appears to be both a disease and a risk factor for other diseases. At the highest end of the blood pressure distribution, there is an increased probability of premature death secondary to stroke, heart disease, or kidney failure. Lower on the distribution curve (for example, diastolic blood pressure of 90–104 mmHg, which is referred to as mild hypertension), the absolute risk of premature mortality is lower and continues to decline with further decreases in blood pressure. High blood pressure is thus a disease when its value is very high and a risk factor throughout its distribution. For diagnostic purposes, blood pressure is considered high when persistently above 140/90 mmHg.

Some cases of very high blood pressure are due to specific causes that may be surgically remediable. Most hypertension, however, results from the combination of a genetic predisposition and an environmental factor such as excessive sodium intake, sedentary habits, and stress.

High blood pressure can be controlled. Mild cases are treated by losing excess weight and reducing the intake of sodium and alcohol. More serious cases are treated with drugs such as diuretics, beta blockers, calcium antagonists, angiotensin-converting enzyme inhibitors, alpha blockers, and centrally acting compounds that affect regulatory centers in the brain. Treatment can usually assure a normal life. See also Heart disorders.

World of the Body: hypertension

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High blood pressure. There is no exact level of blood pressure which labels a person hypertensive, but values as high as 160 mm Hg/90 mm Hg (= systolic/diastolic; highest and lowest in the period of one heart beat) would generally be regarded as marginal in someone at rest. A systolic blood pressure higher than this is reached by healthy people in heavy exercise, and if the exercise is ‘static’ (isometric), both systolic and diastolic are higher; but ‘hypertension’ is a term usually reserved for abnormally high pressure at rest.

— Stuart Judge

See blood pressure.

Food and Nutrition: hypertension

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High blood pressure; a risk factor for ischaemic disease, stroke, and kidney disease. May be due to increased sensitivity to salt (correctly sensitivity to sodium), and treated by restriction of salt intake, together with drugs; increased intake of fruits and vegetables (as a safe source of potassium) is recommended. See also ‘salt-free’ diet.

Food and Fitness: hypertension

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Chronic, persistent, high blood pressure. Approximately one in four adults in the United States suffers from hypertension. Hypertension increases the risk of heart attack, stroke, and kidney failure because it adds to the workload of the heart, causing it to enlarge and, over a period of time, to weaken. In addition, it may damage the walls of the arteries. It is regarded as the silent killer because it can develop without symptoms. It is estimated that half of those with hypertension are not even aware of their condition. In adults, hypertension occurs when the blood pressure of a resting person is equal to or greater than 140/90. Regular, vigorous aerobic exercise at a safe level can help to prevent hypertension and reduce blood pressure. Moderating the intake of fat, salt, and alcohol also has beneficial effects. Smoking tobacco adds to the risk of hypertension.

Alternative Medicine Encyclopedia: Hypertension

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Definition

Hypertension is the medical term for high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries, it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls are narrow, or constricted.

Blood pressure is highest when the heart beats to pump blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers blood pressure above 140 over 90 high for adults.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age sixty and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It is also more common in African-Americans than in white Americans.

If left untreated, hypertension can lead to the following medical conditions:

arteriosclerosis, also called atherosclerosis
blindness
heart attack
stroke
enlarged heart
kidney damage

Causes & Symptoms

Many different actions or situations can normally raise blood pressure. Physical activity can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has multiple high blood pressure readings over a period of time.

The cause of hypertension is not known in 90–95% of the people who have it. Hypertension without a known cause is called primary or essential hypertension. When a person has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

Cushing's syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin, and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescribed drugs, alcoholism, and pregnancy.

Even though the cause of most hypertension is not known, some people have risk factors that give them a greater chance of getting hypertension. Many of these risk factors can be changed to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.

Risk factors for hypertension include:

age over 60
male sex
race (The African-American community has a higher incidence of hypertension.)
heredity

salt sensitivity
obesity
inactive lifestyle
heavy alcohol consumption
use of oral contraceptives

Some risk factors for hypertension can be changed, while others cannot. Age, male sex, and race are risk factors that a person cannot deter. Some people inherit a tendency to get hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. People with these risk factors can avoid or eliminate the other risk factors to lower their chance of developing hypertension.

Diagnosis

Because hypertension does not cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heartbeats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

A number of such factors as pain, stress, or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on the basis of only one high blood pressure reading. If a blood pressure reading is 140/90 or higher for the first time, the physician will have the person return for another blood pressure check. Diagnosis of hypertension usually is made based on two or more readings after the first visit. Sometimes, patients have high blood pressure only while in the doctor's office. This phenomenon, called "white-coat hypertension" has usually been dismissed as mere anxiety over visiting the doctor. In late 2001, an Italian study questioned dismissal of these patients as not being hypertensive and encouraged further study.

Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic is elevated, e.g. 170/70 mm Hg. This condition usually coexists with hardening of the arteries (atherosclerosis).

Blood pressure measurements are classified in stages according to severity:

normal blood pressure: lower than 130/85 mm Hg
high normal: 130–139/85–89 mm Hg
mild hypertension: 140–159/90–99 mm Hg
moderate hypertension: 160–179/100–109 mm Hg
severe hypertension: 180–209/110–119
very severe hypertension: 210/120 or higher

A typical physical examination to evaluate hypertension includes:

medical and family history
physical examination
ophthalmoscopy: examination of the blood vessels in the eye
chest x ray
electrocardiograph (ECG)
blood and urine tests

The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition to the disorder.

The physical exam may include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, height, and weight are checked and recorded. Internal organs are palpated, or felt, to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with an instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other heart abnormalities, or lung disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be done to further evaluate health and to detect the presence of disorders that might cause hypertension.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Treatment to lower blood pressure usually includes changes in diet and getting regular exercise. Patients with mild or moderate hypertension who do not have damage to the heart or kidneys may first be treated primarily with lifestyle changes.

Lifestyle changes that may reduce blood pressure by about 5–10 mm Hg include:

reducing salt intake
reducing fat intake
losing weight
getting regular exercise
quitting smoking
reducing alcohol consumption
managing stress

Natural remedies approved by a physician may also lower or even prevent hypertension. Aromatherapy as a treatment option uses essential oils either inhaled from a bottle in times of anxiety or massaged daily into the skin at bedtime in the area beneath the collarbone. Blue chamomile and lavender are known for their stress relief and relaxation effects.

Food therapy has also been shown to affect blood pressure. Muscles that regulate blood pressure have been noted to dilate with the intake of celery; celery juice has also been found to have a mild diuretic effect. Eating fresh fruits and vegetables, which are high in potassium and magnesium, lowers systemic sodium and fluid levels in the circulatory system. A 2001 study showed that reducing intake of sodium decreases blood pressure in participants with or without hypertension. Garlic intake has also been linked with lowering blood pressures. Taken either via enteric-coated capsules or fresh garlic cloves, allicin is thought to be the ingredient that brings down the blood pressure.

Relaxation and meditation can help lower blood pressure. Focusing on relaxing music can also slow the heart rate and lower blood pressure, as can imagery (envisioning coolness seeping into the pores and throughout the body, sensing that blood pressure is within normal range). Yoga experts cite two specific poses, the corpse pose and the knee squeeze, when used in combination with breathing exercises, as being particularly helpful in relieving tension and improving blood flow.

Allopathic Treatment

Patients whose blood pressure remains higher than 139/90 will most likely be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

Patients with mild or moderate hypertension are initially treated with monotherapy, a single antihypertensive medicine. If treatment with a single medicine fails to lower blood pressure sufficiently, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of medicines to control their hypertension. Combining antihypertensive medicines with different types of action often controls blood pressure with smaller doses of each drug than would be needed for monotherapy.

Antihypertensive medicines fall into several classes:

diuretics
beta-blockers
calcium channel blockers
angiotensin-converting enzyme inhibitors (ACE inhibitors)
alpha-blockers
alpha-beta blockers
vasodilators
peripheral-acting adrenergic antagonists
centrally-acting agonists

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and the blood. This helps reduce the swelling caused by fluid buildup in the tissues. The reduction of fluid dilates the walls of arteries and lowers blood pressure.

Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart's contraction. They are used with caution in patients with heart failure, asthma, diabetes, or circulation problems in the hands and feet.

Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors block the production of substances that constrict blood vessels. They also help reduce the buildup of water and salt in the tissues. They are often given to patients with heart failure, kidney disease, or diabetes. ACE inhibitors may be used together with diuretics.

Alpha-blockers act on the nervous system to dilate arteries and reduce the force of the heart's contractions.

Alpha-beta blockers combine the actions of alpha and beta blockers.

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Peripheral-acting adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause slowed mental function and lethargy.

Centrally-acting agonists also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.

In 2001, a medical device company announced findings about the effectiveness of a breathing device to work along with antihypertensive medications. By helping patients alter breathing patterns to lengthen the phase in which they exhale, they could slow breathing and see beneficial effects on blood pressure accumulate. The device is available through prescription only, but is pending over-the-counter-clearance from the Food and Drug Administration (FDA.)

Expected Results

There is no cure for hypertension. However, it can be well controlled with the proper treatment. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.

Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or sex or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same lifestyle changes recommended for treating hypertension.

Resources

Book

Bellenir, Karen, and Peter D. Dresser, eds. Cardiovascular Diseases and Disorders Sourcebook. Detroit: Omnigraphics, 1995.

Texas Heart Institute. Heart Owner's Handbook. New York: John Wiley and Sons, 1996.

Periodicals

Boschart, Sherry. "Guided Breathing Exercise May Help Cut Hypertension (Preliminary Trial Results)." Internal Medicine News 34, no. 21 (November 1, 2001): 30–31.

"Study Suggests White-Coat Hypertension is Not Harmless." Medical Devices and Surgical Technology Week (December 23, 2001): 26.

Vollmer, William M., et al. "Effects of Diet and Sodium Intake on Blood Pressure: Subgroup Analysis of the DASH-Sodium Trail." Annals of Internal Medicine 135, no. 12 (December 18, 2001): 1019–1020.

Organization

American Heart Association. 7272 Greenview Avenue, Dallas, TX 75231-4596. (800) AHS-USA1. .

National Heart, Lung, and Blood Institute. Information Center. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222.

Texas Heart Institute. Heart Information Service, PO Box 20345, Houston, TX 77225-0345. (800) 292-2221.

[Article by: Kathleen Wright; Teresa G. Odle]

Children's Health Encyclopedia: Hypertension

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Definition

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries, it pushes against the inside of artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure is. The size of arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constricted.

Blood Pressure Measurements

The National Heart, Lung, and Blood Institute in Bethesda, Maryland released clinical guidelines for blood pressure in 2003, lowering the standard normal readings for adults to less than 120 over less than 80.

Although there are set blood pressure ranges for adults, normal blood pressure ranges for children vary according to age, gender, and height so that different levels of growth are considered when evaluating blood pressure. In children, blood pressure normally rises during growth and maturation and varies greatly during adolescence.

Specific systolic and diastolic blood pressure percentiles have been established for each age, gender, and height group. In children ages six to 12, up to 125/80 mm Hg is considered normal. In youth ages 12–15, 126/78 mm Hg is normal, and for ages 16–18, 132/82 mm Hg is normal.

Children whose blood pressure is above the 95th percentile for their age/gender/height group are diagnosed with hypertension. Children whose blood pressure is between the 90th and 95th percentile are diagnosed with pre-hypertension. Adolescents whose blood pressure is greater than 120/80 also may be diagnosed with pre-hypertension.

Complications

Childhood hypertension is serious because it increases the risk of heart disease, stroke, and other medical problems in adulthood. Serious complications can be avoided by ensuring the child gets regular blood pressure checks and by treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following long-term complications:

atherosclerosis, also called arteriosclerosis
peripheral vascular disease
heart attack
stroke
enlarged heart and heart failure
kidney damage or kidney failure
retinopathy or blindness

Atherosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots also can get trapped in narrowed arteries, blocking the flow of blood. When atherosclerosis occurs in the blood vessels leading to the legs and feet, it is called peripheral vascular disease. Blood flow is decreased to the legs and feet with peripheral vascular diseases and can cause poor circulation in the legs, claudication, or aneurysm.

Arteries narrowed by atherosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

Hypertension can cause damage to blood vessels in the eyes, leading to retinopathy, or damage to the retina. Retinal damage becomes severe when blood pressure levels are high and remain elevated for a prolonged period of time.

Demographics

In the United States, an estimated 5–10 percent of children have hypertension, and one in four adults (about 50 million) have hypertension. About 30 percent of those with hypertension do not know they have it. Hypertension is more common in men than women and in people over age 65 than in younger persons. It also is more frequent and severe in African-American and Mexican-American adults and children than in white Americans. The prevalence of high blood pressure among African-Americans and whites in the southeastern United States is greater, and death rates from stroke are higher than among those in other regions.

In the early 2000s, high blood pressure in children and adolescents is on the rise. A 2003 report indicated this increase is most likely due to a greater number of overweight and obese children and adolescents. The U.S. Centers for Disease Control and Prevention studied the health and nutrition of Americans in the National Health and Nutrition Examination Surveys for more than 40 years, and the last data were collected in 2000. Researchers found a trend of high blood pressure in children ages eight to 17 years who were overweight or obese.

Causes and Symptoms

Causes

Many different actions or situations can normally raise blood pressure. Physical activity and changes in position can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. Certain medications also may change blood pressure, but usually blood pressure returns to normal when the drug is discontinued. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has at least three separate high blood pressure readings performed one to several weeks apart.

Hypertension without a known cause is called primary or essential hypertension. Although the cause of hypertension is unknown in 90–95 percent of adults, primary hypertension is uncommon in children, occurring in less than 1–2 percent of hypertensive children.

When a child has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Kidney disease causes hypertension in 80–85 percent of childhood cases. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

As body weight increases, blood pressure rises. Being overweight or obese is the strongest predictor of hypertension in young adults. Obesity has steadily increased in children and adolescents over the years. An estimated 16 percent of school-age children are over-weight. High blood pressure develops about 10 years after a young person becomes overweight. Obesity may cause other cardiovascular diseases if it is not managed or treated properly.

Risk Factors

Risk factors are conditions that increase the chance of developing hypertension. Some of these risk factors can be changed to reduce the risk of developing hypertension or to lower blood pressure:

being overweight or obese
lack of physical activity
a diet high in fat, salt, and sugar
heredity
low birth weight and subsequent rapid weight gain
male sex
race
congenital conditions, such as coarctation of the aorta
diabetes
kidney disease
in adolescents, heavy alcohol consumption and use of oral contraceptives
in adults, being over the age of 60

Although smoking is not directly related to high blood pressure in children and adolescents, those who smoke should stop to reduce their risk of developing other health problems such as coronary artery disease.

Some risk factors for hypertension can be changed, while others cannot. Some children inherit a tendency to develop hypertension, and the risk increases if both parents are hypertensive. Children who have the risk factors above can work with their doctor and family to manage the controllable risk factors.

Symptoms

Hypertension generally does not cause symptoms. When symptoms occur, they are usually mild and non-specific. In young children (age three and younger), symptoms may include:

irritability
excessive crying
failure to gain weight
poor feeding
low-grade fever

In older children, symptoms may include:

dizziness
headaches
vomiting
heart palpitations

In severe and acute (sudden-onset) cases, hypertension can cause seizures, swelling throughout the body, blindness, or renal (kidney) failure. All of these symptoms require immediate medical attention and hospitalization.

When to Call the Doctor

If a child has any of the following symptoms, the parent or caregiver should call the child's doctor:

unexplained headache
sudden or gradual changes in vision
dizziness or light-headedness that does not resolve with rest
nausea associated with headache
unexplained or uncontrollable vomiting
heart palpitations

If a child has any of these symptoms, the parent or caregiver should immediately seek emergency medical attention:

severe headache
fainting
seizures or convulsions
swelling throughout the body
unexplained blurred vision or vision loss
severe chest pain or shortness of breath
unexplained sudden weakness

Diagnosis

Blood pressure in children should be checked regularly: at least at every doctor's visit after age three. Early detection and treatment of hypertension improve the child's overall health and decrease the risk of future health problems associated with hypertension.

Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heartbeats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

The arm cuff used to measure blood pressure in children must be appropriate to the child's size, or the reading may be inaccurate.

A typical physical examination to evaluate hypertension includes:

medical and family history
physical examination
ophthalmoscopy: examination of the blood vessels in the eye
blood and urine tests

The physical exam may include several blood pressure readings at different times and in different positions. For at least five minutes before the blood pressure reading is taken, the child should be seated in a chair, with feet on the floor and arms supported at heart level. For best results, the child should not eat or drink caffeinated products within the 30 minutes prior to the exam. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries.

During the physical exam, the child's pulse, reflexes, and height and weight are checked and recorded. Internal organs are palpated to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with a instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

Urine and blood tests may be done to evaluate health and to detect the presence of certain substances that may indicate an underlying condition that is causing the hypertension.

Usually blood tests and urine tests, along with the physical examination and medical history, are enough to make the diagnosis of hypertension. If necessary, to rule out other medical conditions or to assess any damage from hypertension and/or its treatment, the following tests may be performed:

Chest x ray: To detect an enlarged heart, other vascular abnormalities, or lung disease.
Electrocardiogram (ECG): To measure the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.
Echocardiogram (echo): To produce a graphic outline of the heart's movement, valves, and chambers, used to evaluate the function of the heart and valves. Echo is often combined with Doppler ultrasound and color Doppler. During the echo, an ultrasound transducer (hand-held wand placed on the skin of the chest) emits high-frequency sound waves to produce pictures of the heart's valves and chambers. An echo is used in pediatric patients diagnosed with hypertension to determine the extent of left ventricular hypertrophy, a condition in which the heart's main pumping vessel is enlarged.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension that could manifest in adulthood. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Clinicians should work with the child and the parents or caregivers to develop an individual treatment plan. Specific treatment goals vary. Treatment should be provided by a pediatric cardiologist or pediatrician with special knowledge and experience in the treatment of high blood pressure.

Lifestyle Changes

Depending on the results of diagnostic tests, childhood hypertension is generally treated with lifestyle changes, including diet and exercise, before antihypertensive medication is prescribed. Lifestyle changes that may reduce blood pressure include:

losing weight
exercising regularly
reducing fat, salt, and sugar in the diet
managing stress and anxiety
quitting smoking and reducing alcohol consumption, as applicable in older children

Reaching and maintaining a healthy body weight is important. Overweight children with hypertension are recommended to lose weight until they are within 15 percent of their healthy body weight. Even a small amount of weight loss can make a major difference. Physical activities should be encouraged, and sedentary activities such as watching television or playing video games should be limited. The recommended exercise goal is aerobic activity, such as brisk walking, at least 30 minutes per day, most days of the week.

A pediatrician can calculate a healthy range of body weight for the child, recommend dietary guidelines, and provide activity guidelines to help the child safely and effectively lose weight. A consultation with a registered dietitian also may assist the parent or caregiver in implementing dietary changes.

Nutritional Concerns

Dietary guidelines are individualized, based on the child's blood pressure levels and specific needs. In children older than two years of age, the following low-fat dietary guidelines are recommended:

Total fat intake should comprise 30 percent or less of total calories consumed per day.
Calories consumed as saturated fat should equal no more than 8 to 10 percent of total calories consumed per day.
Total cholesterol intake should be less than 300 mg/dl per day.

Elevated blood pressure can be reduced by an eating plan that emphasizes fruits, vegetables, and low-fat dairy foods, and which is low in saturated fat, total fat, and cholesterol. The DASH diet is recommended for patients with hypertension and includes whole grains, poultry, fish, and nuts. Fats, red meats, sodium, sweets, and sugar-sweetened beverages are limited. Sodium should also be reduced to no more than 1,500 milligrams per day.

A gradual transition to a heart-healthy diet can help decrease a child's risk of coronary artery disease and other health conditions in adulthood. Parents can replace foods high in fat with grains, vegetables, fruits, lean meat, and other foods low in fat and high in complex carbohydrates and protein. They can resist adding salt to foods while cooking and avoid highly processed foods that are usually high in sodium, such as fast foods, canned foods, boxed mixes, and frozen meals.

Alternative Treatment

Alternative and complementary therapies include approaches that are considered to be outside the mainstream of traditional health care.

Techniques that induce relaxation and reduce stress, such as yoga, tai chi, meditation, guided imagery, and relaxation training, may be helpful in controlling blood pressure. Acupuncture and biofeedback training also may help induce relaxation. Before learning or practicing any particular technique, it is important for the parent/caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients.

Dietary supplements, including garlic, fish oil (omega-3 fatty acids), L-arginine, soy, coenzyme Q10, phytosterols, and chelation therapy may be beneficial, but the exact nature of their effects on blood pressure is unknown. There is little scientific evidence that these therapies lower blood pressure or prevent the complications of high blood pressure, and most of these supplements have not been studied extensively in children and adolescents.

Vitamin E and beta carotene supplements were once thought to help prevent the development of heart disease, but subsequent studies disprove that assumption.

Medications

Medications usually are not prescribed for children as a first-line treatment for hypertension. Medications are prescribed, however, to treat hypertension when the child has significant high blood pressure or organ damage, or when diet and exercise are not adequately controlling the child's blood pressure.

Follow-Up Care

Follow-up care for hypertension includes home blood pressure monitoring. The parent or caregiver checks the child's blood pressure at different times of the day and records the readings. The doctor reviews this blood pressure record during the child's check-ups to evaluate the effectiveness of the child's treatment and to make any necessary adjustments.

Depending on the child's blood pressure levels and presence of other medical conditions such as diabetes, the doctor may recommend annual eye exams to detect the presence of vision changes and the development of retinopathy.

Prognosis

There is no cure for hypertension. However, it can be well controlled with the proper treatment. Therapy with a combination of lifestyle changes and sometimes antihypertensive medicines usually can manage blood pressure. For most children, early primary hypertension causes no immediate risk of serious health problems, but it does increase the risk for future organ damage. The key to avoiding serious complications of hypertension is to detect and treat it at the earliest possible age so that preventive treatment can be initiated.

Prevention

Avoiding or eliminating known risk factors helps reduce the risk of developing hypertension. Making the same changes recommended for treating hypertension can reduce a child's risk of developing hypertension:

losing weight if overweight or obese
exercising regularly
reducing salt, fat, and sugar in the diet
reducing fat intake
managing stress and anxiety
quitting smoking and limiting alcohol, as applicable in older children

Parental Concerns

Parents should reinforce with the child that hypertension is a serious condition that can cause more health problems later in life. Parents should work with their child to make dietary changes and increase their activity level to manage hypertension and prevent it from getting worse. Everyone can benefit when a heart-healthy lifestyle is followed, so the dietary and activity changes made for the hypertensive child will benefit the entire family.

Resources

Books

McGoon, Michael D., and Bernard J. Gersh, eds. Mayo Clinic Heart Book: The Ultimate Guide to Heart Health, 2nd ed. New York: William Morrow and Co., Inc., 2000.

Moore, Thomas, et al. The Dash Diet for Hypertension: Lower Your Blood Pressure in Fourteen Days without Drugs. New York: Simon & Schuster, Inc., 2001.

Topol, Eric J. Cleveland Clinic Heart Book: The Definitive Guide for the Entire Family from the Nation's Leading Heart Center. New York: Hyperion, 2000.

Trout, Darrell, and Ellen Welch. Surviving with Heart: Taking Charge of Your Heart Care. Golden, CO: Fulcrum Publishing, 2002.

Periodicals

McNamara, Damian. "Obesity Behind Rise in Incidence of Primary Hypertension." Family Practice News (April 1, 2003): 45–51.

——. "Trial Shows Efficacy of Lifestyle Changes for Blood Pressure: More Intensive than Typical Office Visit." Family Practice News (July 1, 2003): 1–2.

"New Blood Pressure Guidelines Establish Diagnosis of Prehypertension: Level Seeks to Identify At-risk Individuals Early." Case Management Advisor (July 2003): S1.

Sorof, Jonathan M., et al. "Cardiovascular risk factors and sequelae in hypertensive children identified by referral versus school-based screening." Hypertension 43 (2004): 214.

Organizations

American College of Cardiology. Heart House, 9111 Old Georgetown Rd., Bethesda, MD 20814–1699. Web site: www.acc.org.

American Heart Association. 7320 Greenville Ave., Dallas, TX 75231. Web site: www.americanheart.org.

American Society of Hypertension. 148 Madison Ave., 5th Floor, New York, NY 10016. Web site: www.ash-us.org.

The Cleveland Clinic Heart Center. The Cleveland Clinic Foundation, 9500 Euclid Ave., F25, Cleveland, OH 44195. Web site: www.clevelandclinic.org/heartcenter.

[Article by: Toni Rizzo Teresa G. Odle Angela M. Costello]

Columbia Encyclopedia: hypertension

Top

hypertension or high blood pressure, elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels (arterioles). Hypertension is generally defined as a blood pressure reading greater than 140 over 90; presssures of 120–139 over 80–89 are now considered prehypertension. When the cause is unknown, the hypertension is called primary, or essential, hypertension. When a cause can be identified (e.g., a disorder of the adrenal glands, kidneys, or arteries), the condition is known as secondary hypertension. Factors such as heredity, obesity, smoking, and emotional stress are thought to play a role; the usual immediate cause is an imbalance in the body's vasoconstriction/fluid retention systems, often involving a decrease in the kidney's secretion of the regulatory hormone, renin.

Known as the “silent killer,” hypertension often produces few overt symptoms; it may, however, result in damage to the heart, eyes, kidneys, or brain and ultimately lead to congestive heart failure, heart attack (see infarction), kidney failure, or stroke. African Americans and women are the most affected. Treatment of hypertension includes diets to reduce weight and salt and alcohol intake, increased exercise, quitting smoking, and various drugs, such as diuretics, ACE inhibitors, beta-blockers, calcium-channel blockers or angiotensin-receptor blockers, as well as biofeedback. Many patients require a combination of drugs to control their blood pressure. Treatment for persons with prehypertension includes dietary and other lifestyle changes. Recent research has questioned the importance of dietary salt as a major contributor to hypertension; some studies point to low calcium intake as a cause.

Hypertension
Classification and external resources

Automated arm blood pressure meter showing arterial hypertension (shown a systolic blood pressure 158 mmHg, diastolic blood pressure 99 mmHg and heart rate of 80 beats per minute).
ICD-10	I 10.,I 11.,I 12., I 13.,I 15.
ICD-9	401.x
OMIM	145500
DiseasesDB	6330
MedlinePlus	000468
eMedicine	med/1106 ped/1097 emerg/267
MeSH	D006973

Classification

The variation in pressure in the left ventricle (blue line) and the aorta (red line) over two cardiac cycles ("heart beats"), showing the definitions of systolic and diastolic pressure.

A recent classification recommends blood pressure criteria for defining normal blood pressure, prehypertension, hypertension (stages I and II), and isolated systolic hypertension, which is a common occurrence among the elderly. These readings are based on the average of seated blood pressure readings that were properly measured during 2 or more office visits. In individuals older than 50 years, hypertension is considered to be present when a person's blood pressure is consistently at least 140 mmHg systolic or 90 mmHg diastolic. Patients with blood pressures over 130/80 mmHg along with Type 1 or Type 2 diabetes, or kidney disease require further treatment.^[8]

Classification	Systolic pressure		Diastolic pressure
Classification	mmHg	kPa (kN/m²)	mmHg	kPa (kN/m²)
Normal	90–119	12–15.9	60–79	8.0–10.5
Prehypertension	120–139	16.0–18.5	80–89	10.7–11.9
Stage 1	140–159	18.7–21.2	90–99	12.0–13.2
Stage 2	≥160	≥21.3	≥100	≥13.3
Isolated systolic hypertension	≥140	≥18.7	<90	<12.0
Source: American Heart Association (2003).^[8]

Resistant hypertension is defined as the failure to reduce blood pressure to the appropriate level after taking a three-drug regimen (include thiazide diuretic).^[8] Guidelines for treating resistant hypertension have been published in the UK,^[9] and US.^[10] Its worth mentioning that excessive elevation in blood pressure during exercise, is called Exercise hypertension,^[11]^[12]^[13] The upper normal systolic values during exercise reach levels between 200 and 230 mm Hg.^[14] exercise hypertension may be regarded as a precursor to established hypertension at rest.^[13]^[14]

Signs and symptoms

Headaches are a common symptom of hypertension

Mild to moderate essential hypertension is largely asymptomatic.^[15]^[16]^[17]^[18]^[19] The most frequent symptom, headache, is also very nonspecific. Accelerated hypertension is associated with somnolence, confusion, visual disturbances, and nausea and vomiting (hypertensive encephalopathy). Retinas are affected with narrowing of arterial diameter to less than 50% of venous diameter, copper or silver wire appearance, exudates, hemorrhages, or papilledema.^[20] Some signs and symptoms are especially important in infants and neonates such as failure to thrive, seizure, irritability or lethargy, and respiratory distress.^[21] While in children hypertension may cause headache, fatigue, blurred vision, epistaxis, and bell palsy.^[21]

Image showing patient with growth hormone excess

Some signs and symptoms are especially important in suggesting a secondary medical cause of chronic hypertension, such as centripetal obesity, "buffalo hump," and/or wide purple abdominal striae and maybe a recent onset of diabetes suggest glucocorticoid excess either due to Cushing's syndrome or other causes. Hypertension due to other secondary endocrine diseases such as hyperthyroidism, hypothyroidism, or growth hormone excess show symptoms specific to these disease such as in hyperthyrodism there may be weight loss, tremor, tachycardia or atrial arrhythmia, palmar erythema and sweating.^[22] Signs and symptoms associated with growth hormone excess such as coarsening of facial features, prognathism, macroglossia,^[23] hypertrichosis, hyperpigmentation, and hyperhidrosis may occur in these patients.^[24]^:499. Other endocrine causes such as hyperaldosteronism may cause less specific symptoms such as numbness, polyuria, polydipsia, hypernatraemia, and metabolic alkalosis.^[25] A systolic bruit heard over the abdomen or in the flanks suggests renal artery stenosis. Also radio femoral delay or diminished pulses in lower versus upper extremities suggests coarctation of the aorta. Hypertension in patients with pheochromocytomas is usually sustained but may be episodic. The typical attack lasts from minutes to hours and is associated with headache, anxiety, palpitation, profuse perspiration, pallor, tremor, and nausea and vomiting. Blood pressure is markedly elevated, and angina or acute pulmonary edema may occur. In primary aldosteronism, patients may have muscular weakness, polyuria, and nocturia due to hypokalemia. Chronic hypertension often leads to left ventricular hypertrophy, which can present with exertional and paroxysmal nocturnal dyspnea. Cerebral involvement causes stroke due to thrombosis or hemorrhage from microaneurysms of small penetrating intracranial arteries. Hypertensive encephalopathy is probably caused by acute capillary congestion and exudation with cerebral edema, which is reversible.^[20]

Signs and symptoms associated with pre-eclampsia and eclampsia, can be proteinuria, edema, and hallmark of eclampsia which is convulsions, Other cerebral signs may precede the convulsion such as nausea, vomiting, headaches, and blindness.^[26]

Causes

Essential hypertension

Main article: Essential hypertension

Hypertension is one of the most common complex disorders. The etiology of hypertension differs widely amongst individuals within a large population.^[27] Essential hypertension is the form of hypertension that by definition, has no identifiable cause. It is the more common type and affects 90-95% of hypertensive patients,^[2]^[3]^[4]^[5] and even though there are no direct causes, there are many risk factors such as sedentary lifestyle,^[28] obesity^[29]^[30]^[31]^[32]^[33] (more than 85% of cases occur in those with a Body mass index greater than 25),^[33] salt (sodium) sensitivity,^[34]^[35]^[36]^[37] alcohol intake,^[38]^[39] and vitamin D deficiency.^[40]^[41]^[42] It is also relate to aging^[43] and to some inherited genetic mutations.^[27]^[44]^[45]^[46]^[47]^[48] Family history increases the risk of developing hypertension.^[49]^[50] Renin elevation is another risk factor, Renin is an enzyme secreted by the juxtaglomerular apparatus of the kidney and linked with aldosterone in a negative feedback loop.^[30]^[51] Also sympathetic overactivity is implicated.^[52]^[32]^[53]^[54]^[55] Insulin resistance which is a component of syndrome X, or the metabolic syndrome is also thought to cause hypertension.^[30]^[52]^[56] Recently low birth weight has been questioned as a risk factor for adult essential hypertension.^[31]^[57]

Secondary hypertension

Main article: Secondary hypertension

On the other hand, secondary hypertension is by definition results from an identifiable cause. This type is important to recognize since its treated differently than essential type by treating the underlying cause.

Many secondary causes can cause hypertension, some are common and well recognized secondary causes such as Cushing's syndrome,^[58] which is a condition where both adrenal glands can overproduce the hormone cortisol. Hypertension results from the interplay of several pathophysiological mechanisms regulating plasma volume, peripheral vascular resistance and cardiac output, all of which may be increased. More than 80% of patients with Cushing's syndrome have hypertension.^[58] Another important cause is the congenital abnormality coarctation of the aorta.

Adrenal

A variety of adrenal cortical abnormalities can cause hypertension, In primary aldosteronism there is a clear relationship between the aldosterone-induced sodium retention and the hypertension.^[59] Another related disorder that causes hypertension is apparent mineralocorticoid excess syndrome which is an autosomal recessive disorder results from mutations in gene encoding 11β-hydroxysteroid dehydrogenase which normal patient inactivates circulating cortisol to the less-active metabolite cortisone.^[60] Cortisol at high concentrations can cross-react and activate the mineralocorticoid receptor, leading to aldosterone-like effects in the kidney, causing hypertension.^[61] This effect can also be produced by prolonged ingestion of liquorice(which can be of potent strength in liquorice candy), can result in inhibition of the 11β-hydroxysteroid dehydrogenase enzyme and cause secondary apparent mineralocorticoid excess syndrome.^[62]^[63]^[64] Frequently, if liquorice is the cause of the high blood pressure, a low blood level of potassium will also be present.^[63] Yet another related disorder causing hypertension is glucocorticoid remediable aldosteronism, which is an autosomal dominant disorder in which the increase in aldosterone secretion produced by ACTH is no longer transient, causing of primary hyperaldosteronism, the Gene mutated will result in an aldosterone synthase that is ACTH-sensitive, which is normally not.^[65]^[66]^[67]^[68]^[69] GRA appears to be the most common monogenic form of human hypertension.^[70] Compare these effects to those seen in Conn's disease, an adrenocortical tumor which causes excess release of aldosterone,^[71] that leads to hypertension.^[72]^[73]^[74]

Another adrenal related cause is Cushing's syndrome which is a disorder caused by high levels of cortisol. Cortisol is a hormone secreted by the cortex of the adrenal glands. Cushing's syndrome can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone (ACTH).^[75] More than 80% of patients with Cushing's syndrome develop hypertension.^[58], which is accompanied by distinct symptoms of the syndrome, such as central obesity, buffalo hump, moon face, sweating, hirsutism and anxiety.^[76]

Kidney

Other well known causes include diseases of the kidney. This includes diseases such as polycystic kidney disease which is a cystic genetic disorder of the kidneys, PKD is characterized by the presence of multiple cysts (hence, "polycystic") in both kidneys, can also damage the liver, pancreas, and rarely, the heart and brain.^[77]^[78]^[79]^[80] It can be autosomal dominant or autosomal recessive, with the autosomal dominant form being more common and characterized by progressive cyst development and bilaterally enlarged kidneys with multiple cysts, with concurrent development of hypertension, renal insufficiency and renal pain.^[81] Or chronic glomerulonephritis which is a disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys.^[82]^[83]^[84] Hypertension can also be produced by diseases of the renal arteries supplying the kidney. This is known as renovascular hypertension; it is thought that decreased perfusion of renal tissue due to stenosis of a main or branch renal artery activates the renin-angiotensin system.^[85]^[86]^[87] also some renal tumors can cause hypertension. The differential diagnosis of a renal tumor in a young patient with hypertension includes Juxtaglomerular cell tumor, Wilms' tumor, and renal cell carcinoma, all of which may produce renin.^[88] another tumor that is well known to cause hypertension is pheochromocytoma^[89] (most often located in the adrenal medulla) increases secretion of catecholamines such as epinephrine and norepinephrine, causing excessive stimulation of adrenergic receptors, which results in peripheral vasoconstriction and cardiac stimulation. This diagnosis is confirmed by demonstrating increased urinary excretion of epinephrine and norepinephrine and/or their metabolites (vanillylmandelic acid).

Medications

Certain medications, especially NSAIDs (Motrin/Ibuprofen) and steroids can cause hypertension.^[90]^[91]^[92]^[93]^[94] High blood pressure that is associated with the sudden withdrawal of various antihypertensive medications is called Rebound Hypertension.^[95]^[96]^[97]^[98]^[99]^[100]^[101] The increases in blood pressure may result in blood pressures greater than when the medication was initiated. Depending on the severity of the increase in blood pressure, rebound hypertension may result in a hypertensive emergency. Rebound hypertension is avoided by gradually reducing the dose (also known as "dose tapering"), thereby giving the body enough time to adjust to reduction in dose. Medications commonly associated with rebound hypertension include centrally-acting antihypertensive agents, such as clonidine^[102] and beta-blockers.^[101]

Pregnancy

Few women of childbearing age have high blood pressure, up to 11% develop hypertension of pregnancy.^[103] While generally benign, it may herald three complications of pregnancy: pre-eclampsia, HELLP syndrome and eclampsia. Follow-up and control with medication is therefore often necessary.^[104]^[105]

Sleep disturbances

Another common and under-recognized cause is sleep apnea,^[106]^[107] which is often best treated with nocturnal nasal continuous positive airway pressure, but other approaches include the Mandibular advancement splint (MAS), UPPP, tonsilectomy, adenoidectomy, septoplasty, or weight loss. Another cause is an exceptionally rare neurological disease called binswanger's disease, causing dementia; it is a rare form of form of multi-infarct dementia, and is one of the neurological syndromes associated with hypertension.^[108]

Pathophysiology

Main article: Pathophysiology of hypertension

A diagram explaining factors affecting arterial pressure

Most of the mechanisms associated with secondary hypertension are generally fully understood. However, those associated with essential (primary) hypertension are far less understood. What is known is that cardiac output is raised early in the disease course, with total peripheral resistance (TPR) normal; over time cardiac output drops to normal levels but TPR is increased. Three theories have been proposed to explain this:

Inability of the kidneys to excrete sodium, resulting in natriuretic factors such as Atrial Natriuretic Factor being secreted to promote salt excretion with the side-effect of raising total peripheral resistance.
An overactive Renin-angiotensin system leads to vasoconstriction and retention of sodium and water. The increase in blood volume leads to hypertension.^[109]^[110]^[111]^[112]^[113]^[114]
An overactive sympathetic nervous system, leading to increased stress responses.^[115]^[116]^[117]^[118]

It is also known that hypertension is highly heritable and polygenic (caused by more than one gene) and a few candidate genes have been postulated in the etiology of this condition.^[119]^[120]^[121]

Diagnosis

Initial assessment of the hypertensive patient should include a complete history and physical examination to confirm a diagnosis of hypertension. Most patients with hypertension have no specific symptoms referable to their blood pressure elevation. Although popularly considered a symptom of elevated arterial pressure, headache generally occurs only in patients with severe hypertension. Characteristically, a "hypertensive headache" occurs in the morning and is localized to the occipital region. Other nonspecific symptoms that may be related to elevated blood pressure include dizziness, palpitations, easy fatigability, and impotence.^[21]

Measuring blood pressure

Main article: Blood pressure

Conventional (mechanical) sphygmomanometer with aneroid manometer and stethoscope, used to measure blood pressure

Diagnosis of hypertension is generally on the basis of a persistently high blood pressure. Usually this requires three separate measurements at least one week apart. Exceptionally, if the elevation is extreme, or end-organ damage is present then the diagnosis may be applied and treatment commenced immediately.

Obtaining reliable blood pressure measurements relies on following several rules and understanding the many factors that influence blood pressure reading.^[122]

For instance, measurements in control of hypertension should be at least 1 hour after caffeine, 30 minutes after smoking or strenuous exercise and without any stress. Cuff size is also important. The bladder should encircle and cover two-thirds of the length of the (upper) arm. The patient should be sitting upright in a chair with both feet flat on the floor for a minimum of five minutes prior to taking a reading. The patient should not be on any adrenergic stimulants, such as those found in many cold medications.

When taking manual measurements, the person taking the measurement should be careful to inflate the cuff suitably above anticipated systolic pressure. The person should inflate the cuff to 200 mmHg and then slowly release the air while palpating the radial pulse. After one minute, the cuff should be reinflated to 30 mmHg higher than the pressure at which the radial pulse was no longer palpable. A stethoscope should be placed lightly over the brachial artery. The cuff should be at the level of the heart and the cuff should be deflated at a rate of 2 to 3 mmHg/s. Systolic pressure is the pressure reading at the onset of the sounds described by Korotkoff (Phase one). Diastolic pressure is then recorded as the pressure at which the sounds disappear (K5) or sometimes the K4 point, where the sound is abruptly muffled. Two measurements should be made at least 5 minutes apart, and, if there is a discrepancy of more than 5 mmHg, a third reading should be done. The readings should then be averaged. An initial measurement should include both arms. In elderly patients who particularly when treated may show orthostatic hypotension, measuring lying sitting and standing BP may be useful. The BP should at some time have been measured in each arm, and the higher pressure arm preferred for subsequent measurements.

BP varies with time of day, as may the effectiveness of treatment, and archetypes used to record the data should include the time taken. Analysis of this is rare at present.

Automated machines are commonly used and reduce the variability in manually collected readings.^[123] Routine measurements done in medical offices of patients with known hypertension may incorrectly diagnose 20% of patients with uncontrolled hypertension^[124]

Home blood pressure monitoring can provide a measurement of a person's blood pressure at different times throughout the day and in different environments, such as at home and at work.^[125] Home monitoring may assist in the diagnosis of high or low blood pressure. It may also be used to monitor the effects of medication or lifestyle changes taken to lower or regulate blood pressure levels.

Home monitoring of blood pressure can also assist in the diagnosis of white coat hypertension. The American Heart Association^[126] states, "You may have what's called 'white coat hypertension'; that means your blood pressure goes up when you're at the doctor's office. Monitoring at home will help you measure your true blood pressure and can provide your doctor with a log of blood pressure measurements over time. This is helpful in diagnosing and preventing potential health problems."

Some home blood pressure monitoring devices also make use of blood pressure charting software. These charting methods provide printouts for the patient's physician and reminders to take a blood pressure reading. However, a simple and cheap way is simply to manually record values with pen and paper, which can then be inspected by a doctor.

Systolic hypertension is defined as an elevated systolic blood pressure. If systolic blood pressure is elevated with a normal diastolic blood pressure, it is called isolated systolic hypertension. Systolic hypertension may be due to reduced compliance of the aorta with increasing age.^[127]

Laboratory tests

Once the diagnosis of hypertension has been made it is important to attempt to exclude or identify reversible (secondary) causes. Secondary hypertension is more common in preadolescent children, with most cases caused by renal disease. Primary or essential hypertension is more common in adolescents and has multiple risk factors, including obesity and a family history of hypertension.^[49] Tests are undertaken to identify possible causes of secondary hypertension, and seek evidence for end-organ damage to the heart itself or the eyes (retina) and kidneys. Diabetes and raised cholesterol levels being additional risk factors for the development of cardiovascular disease are also tested for as they will also require management.^[2] Tests done are classified as follows:

System	Tests
Renal	Microscopic urinalysis, proteinuria, serum BUN (blood urea nitrogen) and/or creatinine
Endocrine	Serum sodium, potassium, calcium, TSH (thyroid-stimulating hormone).
Metabolic	Fasting blood glucose, total cholesterol, HDL and LDL cholesterol, triglycerides
Other	Hematocrit, electrocardiogram, and Chest X-ray
Sources: Harrison's principles of internal medicine^[50] others^[128]^[129]^[130]^[131]^[132]^[133]

Creatinine (renal function) testing is done to identify both the underlying renal disease as a cause of hypertension and, conversely, hypertension causing the onset of kidney damage. It is a baseline for monitoring the possible side-effects of certain antihypertensive drugs later. Glucose testing is done to identify diabetes mellitus. Additionally, testing of urine samples for proteinuria detection is used to pick up an underlying kidney disease or evidence of hypertensive renal damage. Electrocardiogram (EKG/ECG) testing is done to check for evidence of the heart being under strain from working against a high blood pressure. It may also show a resulting thickening of the heart muscle (left ventricular hypertrophy) or of the occurrence of a previously silent cardiac disease (either a subtle electrical conduction disruption or even a myocardial infarction). A Chest X-ray might be used to observe signs of cardiac enlargement or evidence of cardiac failure.

Prevention

The degree to which hypertension can be prevented depends on a number of features including: current blood pressure level, changes in end/target organs (retina, kidney, heart - among others), risk factors for cardiovascular diseases and the age at presentation. Unless the presenting patient has very severe hypertension, there should be a relatively prolonged assessment period within which should be repeated measurements of blood pressure. Following this, lifestyle advice and non-pharmacological options should be offered to the patient, before any initiation of drug therapy.

The process of managing hypertension according the guidelines of the British Hypertension Society suggest that non-pharmacological options should be explored in all patients who are hypertensive or pre-hypertensive. These measures include;

Weight reduction and regular aerobic exercise (e.g., walking) are recommended as the first steps in treating mild to moderate hypertension. Regular exercise improves blood flow and helps to reduce resting heart rate and blood pressure.^[134] Several studies indicate that low intensity exercise may be more effective in lowering blood pressure than higher intensity exercise.^[135] These steps are highly effective in reducing blood pressure, although drug therapy is still necessary for many patients with moderate or severe hypertension to bring their blood pressure down to a safe level.
Reducing dietary sugar intake.
Reducing sodium (salt) in the diet may be effective: It decreases blood pressure in about 33% of people (see above). Many people use a salt substitute to reduce their salt intake.^[136]
Additional dietary changes beneficial to reducing blood pressure includes the DASH diet (dietary approaches to stop hypertension), which is rich in fruits and vegetables and low-fat or fat-free dairy foods. This diet has been shown to be effective based on research sponsored by the National Heart, Lung, and Blood Institute.^[137] In addition, an increase in daily calcium intake has the benefit of increasing dietary potassium, which theoretically can offset the effect of sodium and act on the kidney to decrease blood pressure. This has also been shown to be highly effective in reducing blood pressure.
Discontinuing tobacco use and alcohol consumption has been shown to lower blood pressure. The exact mechanisms are not fully understood, but blood pressure (especially systolic) always transiently increases following alcohol or nicotine consumption. Besides, abstention from cigarette smoking is important for people with hypertension because it reduces the risk of many dangerous outcomes of hypertension, such as stroke and heart attack. Note that coffee drinking (caffeine ingestion) also increases blood pressure transiently but does not produce chronic hypertension.
Reducing stress, for example with relaxation therapy, such as meditation and other mindbody relaxation techniques,^[138] by reducing environmental stress such as high sound levels and over-illumination can be an additional method of ameliorating hypertension. Jacobson's Progressive Muscle Relaxation and biofeedback are also used,^[139] particularly, device-guided paced breathing,^[140]^[141] although meta-analysis suggests it is not effective unless combined with other relaxation techniques.^[142]

Treatment

Lifestyle modifications

Unless hypertension is severe, lifestyle changes such as those discussed in the preceding section are strongly recommended before initiation of drug therapy. Adoption of the DASH diet is one example of lifestyle change repeatedly shown to effectively lower mildly-elevated blood pressure. If hypertension is high enough to justify immediate use of medications, lifestyle changes are initiated concomitantly.

A series of UK guidelines advocate treatment initiation thresholds and desirable targets to be reached as set out in the following table. Of particular note is that for patients with blood pressures between 140-159/80-99 and without additional factors, that only lifestyle actions and regular blood pressure and risk-factor review is proposed.

**UK Hypertension guidelines**^[9]
Thresholds for starting treatment	Group	Target of treatment
>160/100	all those with such persisting readings	<140/90
>140/90	If also:^[9] Cardiovascular risk >20% per 10 years Or have established cardiovascular disease Or have evidence end organ damage Or chronic kidney disease without high levels albuminuria^[143]	<140/90
>130/80	Type 2 Diabetes alone^[144]	<130/80
>135/85	Type 1 Diabetes alone^[145]	<130/80
>130/80	Type 1 Diabetes with microalbuminuria^[145] Or Type 2 Diabetes with kidney, eye or cerebrovascular damage^[146]	<130/80
>130/80	chronic kidney disease with high levels albuminuria^[143]	<125/75

Medications

Main article: Antihypertensive drugs

There are many classes of medications for treating hypertension, together called antihypertensives, which — by varying means — act by lowering blood pressure. Evidence suggests that reduction of the blood pressure by 5–6 mmHg can decrease the risk of stroke by 40%, of coronary heart disease by 15–20%, and reduces the likelihood of dementia, heart failure, and mortality from vascular disease.

The aim of treatment should be blood pressure control to <140/90 mmHg for most patients, and lower in certain contexts such as diabetes or kidney disease (some medical professionals recommend keeping levels below 120/80 mmHg).^[147] Each added drug may reduce the systolic blood pressure by 5–10 mmHg, so often multiple drugs are often necessary to achieve blood pressure control.

Commonly used drugs include the typical groups of:^[9]

ACE inhibitors such as captopril, enalapril, fosinopril (Monopril), lisinopril (Zestril), quinapril, ramipril (Altace)
- Angiotensin II receptor antagonists may be used where ACE inhibitors are not tolerated: eg, telmisartan (Micardis, Pritor), irbesartan (Avapro), losartan (Cozaar), valsartan (Diovan), candesartan (Amias)
Calcium channel blockers such as nifedipine (Adalat)^[148] amlodipine (Norvasc), diltiazem, verapamil
Diuretics: eg, bendroflumethiazide, chlortalidone, hydrochlorothiazide (also called HCTZ)

Other additionally used groups include:

Additional diuretics such a furosemide or low-dosages of spironolactone
Alpha blockers such as prazosin, or terazosin. Doxazosin has been shown to increase risk of heart failure, and to be less effective than a simple diuretic.^[149]
Beta blockers such as atenolol, labetalol, metoprolol (Lopressor, Toprol-XL), propranolol. Whilst once first line agents, now less directly used for this in the United Kingdom due to the risk of diabetes.^[150]
Direct renin inhibitors such as aliskiren (Tekturna)

Finally several agents may be given simultaneously:

Combination products (which usually contain HCTZ and one other drug). The advantage of fixed combinations resides in the fact that they increase compliance with treatment by reducing the number of pills taken by the patients. A fixed combination of the ACE inhibitor perindopril and the calcium channel blocker amlodipine, recently been proved to be very effective even in patients with additional impaired glucose tolerance and in patients with the metabolic syndrome.^[151]

Choice of initial medication

Unless the blood pressure is severely elevated, consensus guidelines call for medically-supervised lifestyle changes and observation before recommending initiation of drug therapy. All drug treatments have side effects, and while the evidence of benefit at higher blood pressures is overwhelming, drug trials to lower moderately-elevated blood pressure have failed to reduce overall death rates.

If lifestyle changes are ineffective or the presenting blood pressure is critical, then drug therapy is initiated, often requiring more than one agent to effective lower hypertension. Which type of many medications should be used initially for hypertension has been the subject of several large studies and various national guidelines.

The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) study showed better cost-effectiveness and slightly better outcomes for the thiazide diuretic chlortalidone compared with a calcium channel blocker and an ACE inhibitor in a 33,357-member ethnically mixed study group.^[152] The 1993 consensus recommendation for use of thiazide diuretics as initial treatment stems in part from the ALLHAT study results, which concluded in 2002 that "Thiazide-type diuretics are superior in preventing 1 or more major forms of CVD and are less expensive. They should be preferred for first-step antihypertensive therapy."^[152]

A subsequent smaller study (ANBP2) did not show the slight advantages in thiazide diuretic outcomes observed in the ALLHAT study, and actually showed slightly better outcomes for ACE-inhibitors in older white male patients.^[153]

Thiazide diuretics are effective, recommended as the best first-line drug for hypertension by many experts, and much more affordable than other therapies, yet they are not prescribed as often as some newer drugs.

The consensus recommendations of thiazide diuretics as first-line therapy for hypertension stand against the backdrop that all blood pressure treatments have side-effects. Potentially serious side effects of the thiazide diuretics include hypercholesterolemia, and impaired glucose tolerance with consequent increased risk of developing Diabetes mellitus type 2. The thiazide diuretics also deplete circulating potassium unless combined with a potassium-sparing diuretic or supplemental potassium. On this basis, the consensus recommendations to prefer use of thiazides as first line treatment for essential hypertension have been repeatedly and strongly questioned.^[154]^[155]^[156] However as the Merck Manual of Geriatrics notes, "thiazide-type diuretics are especially safe and effective in the elderly."^[157]

Current UK guidelines suggest starting patients over the age of 55 years and all those of African/Afrocaribbean ethnicity firstly on calcium channel blockers or thiazide diuretics, whilst younger patients of other ethnic groups should be started on ACE-inhibitors. Subsequently if dual therapy is required to use ACE-inhibitor in combination with either a calcium channel blocker or a (thiazide) diuretic. Triple therapy is then of all three groups and should the need arise then to add in a fourth agent, to consider either a further diuretic (eg spironolactone or furosemide), an alpha-blocker or a beta-blocker.^[9] Prior to the demotion of beta-blockers as first line agents, the UK sequence of combination therapy used the first letter of the drug classes and was known as the "ABCD rule".^[9]^[158]

Prognosis

Diagram illustrating the main complications of persistent high blood pressure.

It is based upon several factors including genetics, dietary habits, and overall lifestyle choices. If an individual conscious of their condition takes the necessary preventive measures to lower their blood pressure, they are more likely to have a much better outcome than someone who does not.

Complications

Main article: Complications of hypertension

Hypertension is a risk factor for all clinical manifestations of atherosclerosis since it is a risk factor for atherosclerosis it self.^[159]^[160]^[161]^[162]^[163] It is an independent predisposing factor for heart failure,^[164]^[110] coronary artery disease,^[165]^[166]^[167] stroke,^[91] renal disease,^[168]^[169]^[170] and peripheral arterial disease.^[171]^[172]^[173] it is the most important risk factor for cardiovascular morbidity and mortality, in industrialized countries.^[174] The risk is increased for:

Cerebrovascular accident (CVAs or strokes)^[91]^[166]^[175]^[176]^[177]^[178]^[179]
Myocardial infarction (heart attack)^[91]^[175]^[180]
Hypertensive cardiomyopathy (heart failure due to chronically high blood pressure)^[180]^[181]^[182]^[183]
Left ventricular hypertrophy - thickening of the myocardium (muscle) of the left ventricle of the heart.^[59]^[166]^[184]^[185]^[186]
Hypertensive retinopathy - damage to the retina^[187]^[188]^[189]^[190]^[191]^[192]^[193]^[194]^[195]^[196]^[197]^[198]^[199]
Hypertensive nephropathy^[175]^[200]^[201] - chronic renal failure due to chronically high blood pressure "benign nephrosclerosis".
Hypertensive encephalopathy - confusion, headache, convulsion due to vasogenic edema in brain due to high blood pressure.

Epidemiology

Graph showing, prevalence of awareness, treatment and control of hypertension compared between the four studies of NHANES^[202]

It is estimated that nearly one billion people are affected by hypertension worldwide, and this figure is predicted to increase to 1.5 billion by 2025.^[203] The level of blood pressure regarded as deleterious has been revised down during years of epidemiological studies. A widely quoted and important series of such studies is the Framingham Heart Study carried out in an American town: Framingham, Massachusetts.^[204] The results from Framingham and of similar work in Busselton, Western Australia have been widely applied. To the extent that people are similar this seems reasonable, but there are known to be genetic variations in the most effective drugs for particular sub-populations. Recently (2004), the Framingham figures have been found to overestimate risks for the UK population considerably. The reasons are unclear. Nevertheless the Framingham work has been an important element of UK health policy.

Over 90-95% of adult hypertension is of the essential hypertension type.^[2]^[3]^[4]^[5] It is estimated that 43 million people in the United States have hypertension or are taking antihypertensive medication, which is almost 24% of the adult population.^[205] This proportion changes with race, being higher in blacks and lower in whites and Mexican Americans ; second it changes with age, because in industrialized countries systolic BP rises throughout life, whereas diastolic BP rises until age 55 to 60 years and thus the greater increase in prevalence of hypertension among the elderly is mainly due to systolic hypertension; also geographic patterns, because hypertension is more prevalent in the southeastern United States; another important one is gender, because hypertension is more prevalent in men (though menopause tends to abolish this difference); and finally socioeconomic status, which is an indicator of lifestyle attributes and is inversely related to the prevalence, morbidity, and mortality rates of hypertension.^[2] A series of studies and surveys conducted by National Health and Nutrition Examination Survey (NHANES) between 1976 and 2004 to assess the trends in hypertension prevalence, blood pressure distributions and mean levels, and hypertension awareness, treatment, and control among US adults, aged more than 18 years, showed that there is an increasing pattern of awareness, control and treatment of hypertension, and that prevalence of hypertension is increasing reaching 28.9% as of 2004, with the largest increases among non-Hispanic women.^[202]^[206]

For the secondary hypertension its known that primary aldosteronism is the most frequent endocrine form of secondary hypertension.^[129] The incidence of exercise hypertension is reported to range from 1 to 10% of the total population.^[14]

Hypertension often is part of the metabolic "syndrome X" its co-occurring with other components of the syndrome. The other components are, diabetes mellitus, combined hyperlipidemia, and central obesity.^[207]^[111]^[208]^[209] This is especially occurring among women.^[111] And this co-occurrence will increase the risk of cardiovascular disease and cardiovascular events.^[209]

Children and adolescents

As with adults, blood pressure is a variable parameter in children. It varies between individuals and within individuals from day to day and at various times of the day. And the population prevalence of high blood pressure in the young is increasing.^[210] The epidemic of childhood obesity,^[52] the risk of developing left ventricular hypertrophy, and evidence of the early development of atherosclerosis in children would make the detection of and intervention in childhood hypertension important to reduce long-term health risks.^[210] Most childhood hypertension, particularly in preadolescents, is secondary to an underlying disorder. Renal parenchymal disease is the most common (60 to 70%) cause of hypertension. Adolescents usually have primary or essential hypertension, making up 85 to 95% of cases.^[211]

History

Sushruta

Sushruta (6th century BC) explained hypertension in a manner which matches the modern symptoms of the disease.^[212]

Our modern understanding of hypertension began with the work of physician William Harvey (1578-1657). It was then recognized as a disease a century later by Richard Bright in (1789-1858). The first ever elevated blood pressure in a patient without kidney disease was reported by frederick mahomed (1849-1884).^[213]

Society and culture

Economics

The National Heart, Lung, and Blood Institute (NHLBI) estimated in 2002 that hypertension cost the United States $47.2 billion dollars.^[214]

High blood pressure is the most common chronic medical problem prompting visits to primary health care providers, yet it is estimated that only 34% of the 50 million American adults with hypertension have their blood pressure controlled to a level of <140/90 mm Hg. Thus, about two thirds of Americans with hypertension are at increased risk for cardiovascular events. The medical, economic, and human costs of untreated and inadequately controlled high blood pressure are enormous. Adequate management of hypertension can be hampered by inadequacies in the diagnosis, treatment, and/or control of high blood pressure.^[215] Health care providers face many obstacles to achieving blood pressure control among their patients, including a limited ability to adequately lower blood pressure with monotherapy and a typical reluctance to increase therapy (either in dose or number of medications) to achieve blood pressure goals. Patients also face important challenges in adhering to multidrug regimens and accepting the need for therapeutic lifestyle changes. Nonetheless, the achievement of blood pressure goals is possible, and, most importantly, lowering blood pressure significantly reduces cardiovascular morbidity and mortality, as proved in clinical trials. The medical and human costs of treating preventable conditions such as stroke, heart failure, and end-stage renal disease can be reduced by antihypertensive treatment. The recurrent and chronic morbidities associated with hypertension are costly to treat. Pharmacotherapy for hypertension therefore offers a substantial potential for cost savings.^[216] Recent studies proved that the use of angiotensin receptor blockers for treatment of hypertension is cost-saving and cost-effective treatment compared with other conventional treatment.^[217]^[218]

Awareness

The World Health Organization attributes hypertension, or high blood pressure, as the leading cause of cardiovascular mortality. The World Hypertension League (WHL), an umbrella organization of 85 national hypertension societies and leagues, recognized that more than 50% of the hypertensive population worldwide are unaware of their condition.^[219] To address this problem, the WHL initiated a global awareness campaign on hypertension in 2005 and dedicated May 17 of each year as World Hypertension Day (WHD). Over the past three years, more national societies have been engaging in WHD and have been innovative in their activities to get the message to the public. In 2007, there was record participation from 47 member countries of the WHL. During the week of WHD, all these countries – in partnership with their local governments, professional societies, nongovernmental organizations and private industries – promoted hypertension awareness among the public through several media and public rallies. Using mass media such as Internet and television, the message reached more than 250 million people. As the momentum picks up year after year, the WHL is confident that almost all the estimated 1.5 billion people affected by elevated blood pressure can be reached.^[220]

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hypertension

Contents

Classification

Signs and symptoms

Causes

Essential hypertension

Secondary hypertension

Adrenal

Kidney

Medications

Pregnancy

Sleep disturbances

Pathophysiology

Diagnosis

Measuring blood pressure

Laboratory tests

Prevention

Treatment

Lifestyle modifications

Medications

Choice of initial medication

Prognosis

Complications

Epidemiology

Children and adolescents

History

Society and culture

Economics

Awareness

References