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hypertension

 
American Heritage Dictionary:

hy·per·ten·sion

('pər-tĕn'shən) pronunciation
n.
  1. Arterial disease in which chronic high blood pressure is the primary symptom.
  2. Abnormally elevated blood pressure.

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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.


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.

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.

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.


High blood pressure, i.e. an elevation of arterial blood pressure above the normal range expected for a person of a particular age and sex. It may result from a variety of disorders, such as kidney or endocrine (glandular) disease. However, more often the cause is not known; in these cases it is called essential hypertension. Hypertension is initially symptomless, although severely raised blood pressure may cause headaches and palpitations. It usually requires long-term drug treatment to prevent such complications as damage to arteries (atherosclerosis), heart attack, heart failure, stroke, and kidney failure. Certain individuals are more at risk of hypertension, including people with diabetes mellitus, smokers, and those whose blood lipids (fats) are high (see hyperlipidaemia). Weight loss, a low salt diet, avoidance of excess alcohol and smoking, and regular exercise are important measures to reduce high blood pressure, but for more severe cases drug therapy may be necessary. Drugs used in the treatment of hypertension are known as antihypertensive drugs, of which there are several groups (see angiotensin-converting enzyme inhibitors; alpha blockers; beta blockers; calcium antagonists; diuretics; vasodilators).

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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 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.

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 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.

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 is needed when the kidneys 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]



Gale Nutrition Encyclopedia:

Hypertension

Top
Blood pressure is the force with which blood pushes against the artery walls as it travels through the body. Like air in a balloon, blood fills arteries to a certain capacity—and just as too much air pressure can cause damage to a balloon, too much blood pressure can harm healthy arteries. Blood pressure is measured by two numbers—systolic pressure and diastolic pressure. Systolic pressure measures cardiac output and refers to the pressure in the arterial system at its highest. Diastolic pressure measures peripheral resistance and refers to arterial pressure at its lowest. Blood pressure is normally measured at the brachial artery with a sphygmomanometer (pressure cuff) in millimeters of mercury (mm Hg) and given as systolic over diastolic pressure.

A blood pressure reading thus appears as two numbers. The upper number is the systolic pressure, which is the peak force of blood as the heart pumps it. The lower number is the diastolic pressure, which is the pressure when the heart is filling or relaxing before the next beat. Normal blood pressure for an adult is 120/70 (on average), but normal for an individual varies with the height, weight, fitness level, age, and health of a person.

What Is Hypertension?
Hypertension, or high blood pressure, is defined as a reading of 140/90 on three consecutive measurements at least six hours apart. The definition varies for pregnant women, where hypertension is defined as 140/90 on two consecutive measurements six hours apart. Consistently high blood pressure causes the heart to work harder than it should and can damage the coronary arteries, the brain, the kidneys, and the eyes. Hypertension is a major cause of stroke.


Types of Hypertension
Hypertension is classified as either primary (or essential) hypertension or secondary hypertension. Primary hypertension has no specific origin but is strongly associated with lifestyle. It is responsible for 90 to 95 percent of diagnosed hypertension and is treated with stress management, changes in diet, increased physical activity, and medication (if needed). Secondary hypertension is responsible for 5 to 10 percent of diagnosed hypertension. It is caused by a preexisting medical condition such as congestive heart failure, kidney failure, liver failure, or damage to the endocrine (hormone) system.

Pregnancy-induced hypertension (PIH) may appear in otherwise healthy women after the twentieth week of pregnancy. It is more likely to occur in women who are overweight or obese. PIH may be mild or severe, and it is accompanied by water retention and protein in the urine. About 5 percent of PIH cases progress to preeclampsia. Preeclampsia is characterized by dizziness, headache, visual disturbance, abdominal pain, facial edema, poor appetite, nausea, and vomiting. Severe preeclampsia affects the mother's blood system, kidneys, brain, and other organs. In rare cases, the woman can die. Preeclampsia is more likely to occur during first pregnancies, multiple fetuses, in women with existing hypertension, and in women younger than twenty-five years old or over thirty-five years old. If convulsions occur with PIH, it is called eclampsia. PIH disappears within a few weeks after birth.

Causes of Hypertension
Many prescription and over-the-counter drugs can cause or exacerbate hypertension. For example, corticosteroids and immunosuppressive drugs increase blood pressure in most solid-organ transplant recipients. Medication taken for pain and inflammation such as nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors may raise blood pressure since their antiprostaglandin properties affect the kidneys.

Tobacco products (cigarettes, cigars, smokeless tobacco) contain nicotine, which temporarily increases blood pressure (for about thirty minutes or less). The blood pressure of smokers should be rechecked after thirty minutes if initial readings are high. Nicotine patches that are used for smoking cessation do not appear to increase blood pressure.

There does not appear to be a direct relationship between caffeine and chronic hypertension, even though caffeine intake can cause an acute (rapid but brief) increase in blood pressure. This may be due to the fact that tolerance to caffeine develops rapidly.

Chronic overuse of alcohol is a potentially reversible cause of hypertension. Five percent of hypertension is due to alcohol consumption and 30 to 60 percent of alcoholics have hypertension. Alcohol-induced hypertension is more likely to occur in women than men.

Diet and Hypertension
Sodium intake has been a primary target for hypertension control, though it is ranked fourth as the lifestyle factor associated with hypertension. About 50 percent of individuals appear to be "sodium sensitive." This means that excessive sodium intake tends to increase blood pressure in these groups of people, and they do not appear to excrete excessive amount of salt via the kidneys. Sodium-sensitive individuals include the elderly, obese individuals, and African Americans. The Dietary Guidelines for Americans recommend that adults consume no more than 2,400 milligrams of sodium daily. There are a number of ways to limit sodium in the diet, including:

  • Do not use salt at the table
  • Check food labels for sodium content
  • Choose unprocessed foods
  • Limit processed meats and cheeses
  • Limit pickled meats and vegetables
  • Limit salty snacks
  • Limit intake of soy sauce, BBQ sauce, and other condiments and foods that may be high in sodium
Potassium supplements (2–4 grams daily) have been shown to moderately decrease blood pressure. Fruits and vegetables are excellent sources of potassium. The Dietary Guidelines for Americans recommend that adults consume at least 3,500 milligrams of potassium daily. A diet high in fruits and vegetables has been linked to a decreased risk of both hypertension and stroke. Foods high in omega-3 fatty acids have positive effects on hypertension and cardiovascular disease by relaxing arteries and thinning the blood. In addition, several studies have demonstrated that individuals with hypertension may benefit from daily doses of calcium (800 mg) or magnesium (300 mg).

The DASH Eating Plan
Research has shown that a diet that is low in sodium but rich in calcium, potassium, and magnesium can decrease blood pressure, especially among African Americans. This eating plan is called the DASH (Dietary Approach to Stop Hypertension) eating plan and it is as effective in decreasing blood pressure as some medications commonly used to treat hypertension. The DASH eating plan is based on 2,000 calories a day with 18 percent of the calories coming from protein, 55 percent from carbohydrates, and 27 percent from fats. The eating plan contains less fat than the Food Guide Pyramid, more fruits and vegetables, and includes a serving of nuts.

Pharmacological Treatment of Hypertension
Hypertension is commonly treated with medication, and a combination of two or more drugs is common. Patients are usually given a diuretic to help them excrete excess fluids. However, most diuretics also cause excretion of potassium in the urine, and individuals on diuretics should monitor their potassium intakes. Drugs used to control hyertension include beta-blockers (e.g., atenolol [Tenorim]) which act to slow heart rate and cause some vasodilation (widening of the lumen, or interior, of blood vessels). Drugs that contain calcium channel blockers (e.g., amlopidine [Norvasc]) or angiotensinconverting enzyme (ACE) inhibitors also cause vasodilation.

Lifestyle Treatment of Hypertension
Most of the risk factors for primary hypertension are preventable, and lifestyle modification may prevent as well as treat the condition. Secondary hypertension can be managed by treating the underlying cause. Individuals in the high normal and stage 1 hypertension categories should attempt to lower blood pressure through diet and lifestyle changes before going on a regimen of medications. Recommendations include:

  • Eliminate tobacco
  • Control stress
  • Maintain weight at 15 percent or less of desirable weight
  • Restrict alcohol intake to no more than two drinks a day for men and one for women (one drink equals 12 ounces of beer, 5 ounces of wine, or 1.5 ounces 80-proof whiskey)
  • Restrict sodium intake to 1.5 to 2.5 grams per day (4 to 6 tsp salt)
  • Exercise five to seven days a week for sixty minutes per session
  • Increase intake of fruits and vegetables
  • Increase intake of low-fat dairy products
See also Cardiovascular diseases; Heart disease.

Bibliography
Anderson, Douglas M., et al. (2003). Mosby's Medical, Nursing, and Allied Health Dictionary, 6th edition. St. Louis, MO: Mosby.
Worthington-Roberts, B., and Williams, S. (1997). Nutrition in Pregnancy and Lactation, 6th edition. Madison, WI: Brown and Benchmark.

Internet Resources
Onusko, E. (2003). "Diagnosing Secondary Hypertension." American Family Physician 67:67–74. Also available from http://www.aafp.org/afp
National Heart, Lung, and Blood Institute. "Facts about the DASH Eating Plan." Available from http://www.nhlbi.gov/health
Gale Encyclopedia of Diets:

Hypertension

Top

    Demographics
    Resources

What is Hypertension?

Hypertension is the medical term for high blood pressure. Each time the heartbeats, it forces blood into the arteries. Blood pressure is the force created when blood moving through the body’s arteries pushes against the artery walls. Arteries are the blood vessels that carry blood from the heart throughout the body. Though many factors can cause hypertension, diet plays a major role in controlling high blood pressure.

.

Description of Hypertension

Blood pressure is measured as it pushes against the inside of artery walls. The low blood pressure point, when the heart is at rest, is called diastolic pressure. Blood pressure is measured in millimeters of mercury (mm Hg) and the systolic reading is read and recorded first, with the diastolic pressure reading following. For example, if a person’s high, or systolic, pressure is 118 and his or her low pressure is 70, the blood pressure would be announced and recorded as 118/70 mm Hg, or “118 over 70.” This would fall into the normal range, according to the American Heart Association (AHA). The association’s recommended blood pressure levels are less than 120 mm Hg for systolic pressure and less than 80 mm Hg for diastolic pressure.

If a person’s systolic pressure rises above 120 mm Hg and up to 139 mm Hg or diastolic pressure rises to a level of 80-80 mm Hg, the person is considered “prehypertensive.” High blood pressure is defined as a reading above 140 mm Hg systolic or 90 mm Hg diastolic. If the systolic raises above 160 mm Hg or the diastolic goes above 100, the person is considered in the Stage 2 high blood pressure range. High blood pressure can have serious health consequences. In particular, it is a major risk factor for stroke and heart attack.

Diet is an important part of controlling high blood pressure. A diet to control hypertension consists of eating fewer calories, reducing salt, eating more potassium, reducing alcohol consumption and eating lots of fruits and vegetables. Eating fewer calories and reducing fat, especially saturated fat, will help keep weight down. And lowering weight to normal range usually helps lower blood pressure. Salt is well known as a problem for people with high blood pressure. Most diets for hypertension includes decreasing use of table salt and sodium in processed foods.

Potassium can do the opposite of sodium; it can help lower blood pressure. Potassium is best found in foods rather than in supplements. Foods rich in potassium include apricots, avocados, bananas, melons, kiwis, lima beans, oranges, prunes, spinach, tomatoes, squash, potatoes, and whole grains. Fresh fruits and vegetables are low in sodium, rich in potassium and fiber, as well as vitamins and minerals.

Plant proteins also may help lower blood pressure; the best sources of proteins come from soy products, beans, peas, lentils, peanuts, brown rice, broccoli, and potatoes. A hypertension diet may be supplied by a physician, a center that specializes in heart healthy lifestyles, a nutritionist, or be based on the “DASH” or Dietary Approaches to Stop Hypertension eating plan.

The DASH diet emphasizes lean meats, fish, chicken, low-fat dairy, fruits, vegetables, whole grains, legumes, nuts, and seeds. Vegetarian diets also may help keep blood pressure low. The OmniHeart diet is similar to DASH but may emphasize a particular food group, such as protein, more. Other lifestyle changes, such as quitting cigarette smoking and increasing activity by regularly exercising also may be recommended.

Blood pressure

Normal120/80
Prehypertension120-129/80-84
Hypertension130-139/85-89
Stage 1140/90
Stage 2140-180/90-110
National Heart, Lung and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services.

Columbia Encyclopedia:

hypertension

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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.

See also eclampsia.


Word Tutor:

hypertension

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pronunciation

IN BRIEF: Blood pressure that is much higher than normal.

pronunciation Hypertension is a very dangerous health hazard.

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Wiley Dictionary of Flavors:

Hypertension

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High blood pressure. See Blood Pressure.


the state or condition of having a higher than normal arterial blood pressure.
hypertensive adj.

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Hypertension

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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 I10,I11,I12,
I13,I15
ICD-9 401
OMIM 145500
DiseasesDB 6330
MedlinePlus 000468
eMedicine med/1106 ped/1097 emerg/267
MeSH D006973

Hypertension (HTN) or high blood pressure, sometimes arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is elevated. This requires the heart to work harder than normal to circulate blood through the blood vessels. Blood pressure involves two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed (diastole) between beats. Normal blood pressure is at or below 120/80 mmHg. High blood pressure is said to be present if it is persistently at or above 140/90 mmHg.

Hypertension is classified as either primary (essential) hypertension or secondary hypertension; about 90–95% of cases are categorized as "primary hypertension" which means high blood pressure with no obvious underlying medical cause.[1] The remaining 5–10% of cases (secondary hypertension) are caused by other conditions that affect the kidneys, arteries, heart or endocrine system.

Hypertension is a major risk factor for stroke, myocardial infarction (heart attacks), heart failure, aneurysms of the arteries (e.g. aortic aneurysm), peripheral arterial disease and is a cause of chronic kidney disease. Even moderate elevation of arterial blood pressure is associated with a shortened life expectancy. Dietary and lifestyle changes can improve blood pressure control and decrease the risk of associated health complications, although drug treatment is often necessary in patients for whom lifestyle changes prove ineffective or insufficient.

Contents

Classification

Classification (JNC7)[2] Systolic pressure Diastolic pressure
mmHg kPa mmHg kPa
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 hypertension 140–159 18.7–21.2 90–99 12.0–13.2
Stage 2 hypertension ≥160 ≥21.3 ≥100 ≥13.3
Isolated systolic
hypertension
≥140 ≥18.7 <90 <12.0

Adults

In people aged 18 years or older hypertension is defined as a systolic and/or a diastolic blood pressure measurement consistently higher than an accepted normal value (currently 139 mmHg systolic, 89 mmHg diastolic: see table — Classification (JNC7)). Lower thresholds are used (135 mmHg systolic or 85 mmHg diastolic) if measurements are derived from 24-hour ambulatory or home monitoring.[3] The presence of other cardiovascular risk factors is taken into account when decisions are made regarding drug treatment. Recent international hypertension guidelines have also created categories below the hypertensive range to indicate a continuum of risk with higher blood pressures in the normal range. JNC7 (2003)[2] uses the term prehypertension for blood pressure in the range 120-139 mmHg systolic and/or 80-89 mmHg diastolic, while ESH-ESC Guidelines (2007)[4] and BHS IV (2004)[5] use optimal, normal and high normal categories to subdivide pressures below 140 mmHg systolic and 90 mmHg diastolic. Hypertension is also sub-classified: JNC7 distinguishes hypertension stage I, hypertension stage II, and isolated systolic hypertension. Isolated systolic hypertension refers to elevated systolic pressure with normal diastolic pressure and is common in the elderly.[2] The ESH-ESC Guidelines (2007)[4] and BHS IV (2004),[5] additionally define a third stage (stage III hypertension) for people with systolic blood pressure exceeding 179 mmHg or a diastolic pressure over 109 mmHg. Hypertension is classified as "resistant" if medications do not reduce blood pressure to normal levels.[2]

Neonates and infants

Hypertension in neonates is rare, occurring in around 0.2 to 3% of neonates, and blood pressure is not measured routinely in the healthy newborn.[6] Hypertension can be more common in high risk newborns. A variety of factors, such as gestational age, postconceptional age and birth weight needs to be taken into account when deciding if a blood pressure is normal in a neonate.[6]

Children and adolescents

Hypertension occurs quite commonly in children and adolescents (2-9% depending on age, sex and ethnicity)[7] and is associated with long term risks of ill-heath.[8] It is now recommended that children over the age of 3 have their blood pressure checked whenever they attend for routine medical care or checks, but high blood pressure must be confirmed on repeated visits before characterizing a child as having hypertension.[8] Blood pressure rises with age in childhood and, in children, hypertension is defined as an average systolic or diastolic blood pressure on three or more occasions equal or higher than the 95th percentile appropriate for the sex, age and height of the child. Prehypertension in children is defined as average systolic or diastolic blood pressure that are greater than or equal to the 90th percentile, but less than the 95th percentile.[8] In adolescents, it has been proposed that hypertension and pre-hypertension are diagnosed and classified using the same criteria as in adults.[8]

Signs and symptoms

Hypertension is rarely accompanied by any symptoms, and its identification is usually through screening, or when seeking healthcare for an unrelated problem. A proportion of people with high blood pressure reports headaches (particularly at the back of the head and in the morning), as well as lightheadedness, vertigo, tinnitus (buzzing or hissing in the ears), altered vision or fainting episodes.[9]

On physical examination, hypertension may be suspected on the basis of the presence of hypertensive retinopathy detected by examination of the optic fundi using ophthalmoscopy[10] Classically, the severity of the hypertensive retinopathy changes is graded from grade I–IV, although the milder types may be difficult to distinguish from each other.[10] Ophthalmoscopy findings may also indicate how long a person has been hypertensive.[9]

Secondary hypertension

Some additional signs and symptoms may suggest secondary hypertension, i.e. hypertension due to some identifiable cause such as kidney diseases or endocrine diseases. For example, truncal obesity, glucose intolerance, moon facies, a "buffalo hump" and purple striae suggest Cushing's syndrome.[11] Thyroid disease and acromegaly can also cause hypertension and have characteristic symptoms and signs.[11] An abdominal bruit may be an indicator of renal artery stenosis, while decreased blood pressure in the lower extremities and/or delayed or absent femoral arterial pulses may indicate aortic coarctation. Labile or paroxysmal hypertension accompanied by headache, palpitations, pallor, and perspiration should prompt suspicions of pheochromocytoma.[11]

Hypertensive crises

Severely elevated blood pressure (systolic over 180 or diastolic over 110 — sometime termed malignant or accelerated hypertension) is referred to as a "hypertensive crisis", as blood pressures above these levels are known to confer a high risk of complications. People with blood pressures in this range may have no symptoms, but are more likely to report headaches and dizziness.[9] Other symptoms accompanying a hypertensive crisis may include visual deterioration or breathlessness due to heart failure or a general feeling of malaise due to renal failure.[11] Most people with a hypertensive crisis are known to have elevated blood pressure, but additional triggers may have led to a sudden rise.[12]

A "hypertensive emergency", previously "malignant hypertension", is diagnosed when there is evidence of direct damage to one or more organs as a result of the severely elevated blood presure. This may include hypertensive encephalopathy, caused by brain swelling and dysfunction, and characterised by headaches and an altered level of consciousness (confusion or drowsiness). Retinal papilloedema and/or fundal hemorrhages and exudates are another sign of target organ damage. Chest pain may indicate heart muscle damage (which may progress to myocardial infarction) or sometimes aortic dissection, the tearing of the inner wall of the aorta. Breathlessness, cough, and the expectoration of blood-stained sputum are characteristic signs of pulmonary edema, the swelling of lung tissue due to left ventricular failure an inability of the left ventricle of the heart to adequately pump blood from the lungs into the arterial system.[12] Rapid deterioration of kidney function (acute kidney injury) and microangiopathic hemolytic anemia (destruction of blood cells) may also occur.[12] In these situations, rapid reduction of the blood pressure is mandated to stop ongoing organ damage.[12] In contrast there is no evidence that blood pressure needs to be lowered rapidly in hypertensive urgencies where there is no evidence of target organ damage and over aggressive reduction of blood pressure is not without risks [11] Use of oral medications to lower the BP gradually over 24 to 48 h is advocated in hypertensive urgencies.[12]

In pregnancy

Hypertension occurs in approximately 8-10% of pregnancies.[11] Most women with hypertension in pregnancy have pre-existing primary hypertension, but high blood pressure in pregnancy may be the first sign of pre-eclampsia, a serious condition of the second half of pregnancy and puerperium.[11] Pre-eclampsia is characterised by increased blood pressure and the presence of protein in the urine.[11] It occurs in about 5% of pregnancies and is responsible for approximately 16% of all maternal deaths.[11] Pre-eclampsia also doubles the risk of perinatal mortality.[11] Usually there are no symptoms in pre-eclampsia and it is detected by routine screening. When symptoms of pre-eclampsia occur the most common are headache, visual disturbance (often "flashing lights"), vomiting, epigastric pain, and edema. Pre-eclampsia can occasionally progress to a life-threatening condition called eclampsia, which is a hypertensive emergency and has several serious complications including vision loss, cerebral edema,seizures or convulsions, renal failure, pulmonary edema, and disseminated intravascular coagulation[11][13]

In neonates, infants and children

Failure to thrive, seizures, irritability, lack of energy, and difficulty breathing[14] can be associated with hypertension in neonates and young infants. In older infants and children, hypertension can cause headache, unexplained irritability, fatigue, failure to thrive, blurred vision, nosebleeds, and facial paralysis,[6][14]

Complications

Diagram illustrating the main complications of persistent high blood pressure.

Hypertension is the most important preventable risk factor for premature death worldwide.[15] It increases the risk of ischemic heart disease[16] strokes,[11] peripheral vascular disease,[17] and other cardiovascular diseases, including heart failure, aortic aneurysm, diffuse atherosclerosis, and pulmonary embolism.[11][11] Hypertension is also a risk factor for cognitive impairment and dementia, and chronic kidney disease.[11] Other complications include:

  • Hypertensive retinopathy
  • Hypertensive nephropathy[18]
  • Silent stroke is a type of stroke (infarct) that does not have any outward symptoms (asymptomatic), and the patient is typically unaware they have suffered a stroke. Despite not causing identifiable symptoms a silent stroke still causes damage to the brain, and places the patient at increased risk for a major stroke in the future. Hypertension is the major treatable risk factor associated with silent strokes.[19]

Cause

Primary hypertension

Primary (essential) hypertension is the most common form of hypertension, accounting for 90–95% of all cases of hypertension.[1] In almost all contemporary societies, blood pressure rises with aging and the risk of becoming hypertensive in later life is considerable.[20] Hypertension results from a complex interaction of genes and environmental factors. Numerous common genes with small effects on blood pressure have been identified [21] as well as some rare genes with large effects on blood pressure [22] but the genetic basis of hypertension is still poorly understood. Several environmental factors influence blood pressure. Lifestyle factors that lower blood pressure, include reduced dietary salt intake,[23] increased consumption of fruits and low fat products (Dietary Approaches to Stop Hypertension (DASH diet)), exercise,[24] weight loss [25] reduced alcohol intake,.[26] The possible role of other factors such as stress,[24] caffeine consumption,[27] and vitamin D deficiency [28] are less clear cut. Insulin resistance, which is common in obesity and is a component of syndrome X (or the metabolic syndrome), is also thought to contribute to hypertension.[29] Recent studies have also implicated events in early life (for example low birth weight, maternal smoking and lack of breast feeding) as risk factors for adult essential hypertension,[30] although the mechanisms linking these exposures to adult hypertension remain obscure.

Secondary hypertension

Secondary hypertension results from an identifiable cause. Renal disease is the most common secondary cause of hypertension.[11] Hypertension can also be caused by endocrine conditions, such as Cushing's syndrome, hyperthyroidism, hypothyroidism, acromegaly, Conn's syndrome or hyperaldosteronism, hyperparathyroidism and pheochromocytoma.[11][31] Other causes of secondary hypertension include obesity, sleep apnea, pregnancy, coarctation of the aorta, excessive liquorice consumption and certain prescription medicines, herbal remedies and illegal drugs.[11][32]

Pathophysiology

A diagram explaining factors affecting arterial pressure

In most people with established essential (primary) hypertension, increased resistance to blood flow (total peripheral resistance) accounts for the high pressure and cardiac output is normal.[33] There is evidence that some younger people with prehypertension or 'borderline hypertension' have high cardiac output, an elevated heart rate and normal peripheral resistance, termed hyperkinetic borderline hypertension.[34] These individuals develop the typical features of established essential hypertension in later life as their cardiac output falls and peripheral resistance rises with age.[34] Whether this pattern is typical of all people who ultimately develop hypertension is disputed.[35] The increased peripheral resistance in established hypertension is mainly attributable to structural narrowing of small arteries and arterioles,[36] although a reduction in the number or density of capillaries may also contribute.[37] Hypertension is also associated with decreased peripheral venous compliance[38] which may increase venous return, increase cardiac preload and, ultimately, cause diastolic dysfunction. Whether increased active vasoconstriction plays a role in established essential hypertension is unclear.[39]

Pulse pressure - the difference between systolic and diastolic blood pressure is frequently increased in older people with hypertension. This can mean that systolic pressure is abnormally high, but diastolic pressure may be normal or low — a condition termed isolated systolic hypertension.[40] The high pulse pressure in elderly people with hypertension or isolated systolic hypertension is explained by increased arterial stiffness, which typically accompanies aging and may be exacerbated by high blood pressure.[41]

Many mechanisms have been proposed to account for the rise in peripheral resistance in hypertension. Most evidence implicates either:

and/or

These mechanisms are not mutually exclusive and it is likely that both contribute to some extent in most cases of essential hypertension. It has also been suggested that endothelial dysfunction[44] and vascular inflammation[45] may also contribute to increased peripheral resistance and vascular damage in hypertension.

Diagnosis

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 radiograph
Sources: Harrison's principles of internal medicine[46] others[47][48][49][50][51]

Hypertension is diagnosed on the basis of a persistently high blood pressure. Traditionally,[3] this requires three separate sphygmomanometer measurements at one monthly intervals.[52] Initial assessment of the hypertensive patient should include a complete history and physical examination. With the availability of 24-hour ambulatory blood pressure monitors and home blood pressure machines, the importance of not wrongly diagnosing those who have white coat hypertension has led to a change in protocol advice in the United Kingdom, with best practice of now following up a single raised clinic reading with ambulatory measurement, or less ideally with home blood pressure monitoring over the course of 7 days.[3]

Once the diagnosis of hypertension has been made, physicians will attempt to identify the underlying cause based on risk factors and other symptoms, if present. 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.[53] Laboratory tests can also be performed to identify possible causes of secondary hypertension, and to determine whether hypertension has caused damage to the heart, eyes, and kidneys. Additional tests for diabetes and high cholesterol levels are usually performed because these conditions are additional risk factors for the development of heart disease and require treatment.[1] Typical tests are listed in the table.

Serum creatinine is measured as a test of renal function, to assess the presence of kidney disease, which can be either the cause or the result of hypertension. Serum creatinine alone may overestimate glomerular filtration rate and recent guidelines advocate the use of predictive equations such as the Modification of Diet in Renal Disease (MDRD) formula to estimate glomerular filtration rate (eGFR).[54] eGFR can also provides a baseline measurement of kidney function that can be used to monitor for side effects of certain antihypertensive drugs on kidney function. Additionally, testing of urine samples for protein is used as a secondary indicator of kidney disease. Glucose testing is done to determine if diabetes mellitus is present. Electrocardiogram (EKG/ECG) testing is done to check for evidence that the heart is under strain from high blood pressure. It may also show whether there is thickening of the heart muscle (left ventricular hypertrophy) or whether the heart has experienced a prior minor disturbance such as a silent heart attack. A chest X-ray may be performed to look for signs of heart enlargement or damage to heart tissue.

Prevention

Much of the disease burden of high blood pressure is experienced by people who are not hypertensive.[55] Consequently, population strategies are required to reduce the consequences of high blood pressure and reduce the need for antihypertensive drug therapy. Lifestyle changes are recommended to lower blood pressure, before starting drug therapy. The 2004 British Hypertension Society guidelines[55] proposed the following lifestyle changes consistent with those outlined by the US National High BP Education Program in 2002[56] for the primary prevention of hypertension:

  • maintain normal body weight for adults (e.g. body mass index 20–25 kg/m2)
  • reduce dietary sodium intake to <100 mmol/ day (<6 g of sodium chloride or <2.4 g of sodium per day)
  • engage in regular aerobic physical activity such as brisk walking (≥30 min per day, most days of the week)
  • limit alcohol consumption to no more than 3 units/day in men and no more than 2 units/day in women
  • consume a diet rich in fruit and vegetables (e.g. at least five portions per day);
  • consume a diet with reduced content of saturated and total fat.

Effective lifestyle modification may lower blood pressure as much an individual antihypertensive drug. Combinations of two or more lifestyle modifications can achieve even better results.[55]

Treatment

Lifestyle modifications

The first line of treatment for hypertension is identical to the recommended preventive lifestyle changes [57] and includes: dietary changes[58] physical exercise, and weight loss. These have all been shown to significantly reduce blood pressure in people with hypertension.[59] If hypertension is high enough to justify immediate use of medications, lifestyle changes are still recommended in conjunction with medication. Different programs aimed to reduce psychological stress such as biofeedback, relaxation or meditation are advertised to reduce hypertension. However, in general claims of efficacy are not supported by scientific studies, which have been in general of low quality.[60][61][62]

Regarding dietary changes, a low sodium diet is beneficial. A long term (more than 4 weeks) low sodium diet in Caucasians is effective in reducing blood pressure, both in people with hypertension and in people with normal blood pressure.[63] Also, the DASH diet (Dietary Approaches to Stop Hypertension) is a diet promoted by the National Heart, Lung, and Blood Institute (part of the NIH, a United States government organization) to control hypertension. A major feature of the plan is limiting intake of sodium,[64] and it also generally encourages the consumption of nuts, whole grains, fish, poultry, fruits and vegetables while lowering the consumption of red meats, sweets, and sugar. It is also "rich in potassium, magnesium, and calcium, as well as protein".

Medications

Several classes of medications, collectively referred to as antihypertensive drugs, are currently available for treating hypertension. Drug prescription should take into account the patient's absolute cardiovascular risk (including risk of myocardial infarction and stroke) as well as blood pressure readings, in order to gain a more accurate picture of the patient's cardiovascular profile.[65] If drug treatment is inititated the National Heart, Lung, and Blood Institute's Seventh Joint National Committee on High Blood Pressure (JNC-7)[54] recommends that the physician not only monitor for response to treament but should also assess for any adverse or untoward reaction resulting from the medication(s). Reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34%, of ischaemic heart disease by 21%, and reduce the likelihood of dementia, heart failure, and mortality from cardiovascular disease.[66] The aim of treatment should be to reduce blood pressure to <140/90 mmHg for most individuals, and lower for individuals with diabetes or kidney disease (some medical professionals recommend keeping levels below 120/80 mmHg).[67] If the blood pressure goal is not met, a change in treatment should be made as therapeutic inertia is a clear impediment to blood pressure control.[68] Comorbidity also plays a role in determining target blood pressure, with lower BP targets applying to patients with end-organ damage or proteinuria.[65]

Often multiple medications are needed to be combined to achieve the goal blood pressure. Guidelines on the choice of first line agent and how to best to step up treatment with multiple agents for various subgroups of patients have changed over time and differ between countries.

In the UK low dose thiazide-based diuretic were previously thought the best first line agent,[69] but latest guidelines emphasise calcium channel blockers (CCB) in preference for patients over the age of 55 years or if of African or Caribbean family origin, with angiotensin converting enzyme inhibitors (ACE-I) used first line for younger patients.[70] Preferred dual therapy is generally CCB with an ACE-I, and triple therapy with addition of a thiazide-like diuretic. If a fourth agent is needed then additional diuretics of spironolactone or a higher-dose of a thiazide-like diuretics. Additional agents that may be considered are alpha blockers or beta blockers.[70] Angiotensin II receptor antagonists are suggested as preferable to ACE-I for black people of African or Caribbean family origin, and are an alternative for patients who are unable to tolerate ACE-I. Beta-blockers may be also be considered in younger people, particularly those with an intolerance or contraindication to ACE-I and angiotensin II receptor antagonists, or women of child-bearing potential, or people with evidence of increased sympathetic drive.[70]

Drug combinations

The majority of patients require more than one drug to control their hypertension. JNC7 [54] and ESH-ESC guidelines[4] advocate starting treatment with two drugs when blood pressure is >20 mmHg above systolic or >10 mmHg above diastolic targets. Preferred combinations are renin–angiotensin system inhibitors and calcium channel blockers, or renin–angiotensin system inhibitors and diuretics.[71] Acceptable combinations include calcium channel blockers and diuretics, beta-blockers and diuretics, dihydropyridine calcium channel blockers and beta-blockers, or dihydropyridine calcium channel blockers with either verapamil or diltiazem. Unacceptable combinations are non-dihydropyridine calcium blockers (such as verapamil or diltiazem) and beta-blockers, dual renin–angiotensin system blockade (e.g. angiotensin converting enzyme inhibitor + angiotensin receptor blocker), renin–angiotensin system blockers and beta-blockers, beta-blockers and anti-adrenergic drugs.[71] Combinations of an ACE-inhibitor or angiotensin II–receptor antagonist, a diuretic and an NSAID (including selective COX-2 inhibitors and non-prescribed drugs such as ibuprofen) should be avoided whenever possible due to a high documented risk of acute renal failure. The combination is known colloquially as a "triple whammy" in the Australian health industry.[57]

Fixed dose combinations

Tablets containing fixed combinations of two classes of drugs are available and whilst convenient for the patient, may be best reserved for patients who have been established on the individual components.[72]

In the elderly and very elderly

Treating moderate to severe hypertension decreases death rates and cardiovascular morbidity and mortality in people aged 60 and older.[73] There are limited studies of people over 80 years old but a recent meta-analysis that pooled results from several clinical trials concluded that antihypertensive treatment reduced cardiovascular deaths and disease, but did not significantly reduce total death rates.[73] The recommended BP goal is advised as <140/90 mm Hg with thiazide diuretics being the first line medication in America,[74] but in the revised UK guidelines calcium-channel blockers are advocated as first line with targets of clinic readings <150/90, or <145/85 on ambulatory or home blood pressure monitoring.[70]

Resistant

Guidelines for treating resistant hypertension have been published in the UK[75] and US.[76]

Epidemiology

In the year 2000 it is estimated that nearly one billion people or ~26% of the adult population had hypertension worldwide.[77] It was common in both developed (333 million ) and undeveloped (639 million) countries.[77] However rates vary markedly in different regions with rates as low as 3.4% (men) and 6.8% (women) in rural India and as high as 68.9% (men) and 72.5% (women) in Poland.[78]

In 1995 it is estimated that 43 million people in the United States had hypertension or were taking antihypertensive medication, almost 24% of the adult population.[79] The prevalence of hypertension in the United States is increasing and reached 29% in 2004.[80][81] It is more common in blacks and native Americans and less in whites and Mexican Americans, rates increase with age, and is greater in the southeastern United States. Hypertension is more prevalent in men (though menopause tends to decrease this difference) and those of low socioeconomic status.[1]

In children

The prevalence of high blood pressure in the young is increasing.[82] Most childhood hypertension, particularly in preadolescents, is secondary to an underlying disorder. Aside from obesity, kidney disease is the most common (60–70%) cause of hypertension in children. Adolescents usually have primary or essential hypertension, which accounts for 85–95% of cases.[83]

History

Image of veins from Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus

Modern understanding of the cardiovascular system began with the work of physician William Harvey (1578–1657), who described the circulation of blood in his book "De motu cordis". The English clergyman Stephen Hales made the first measurement of blood pressure in 1733,[84] in horses.[85] Descriptions of hypertension as a disease came among others from Thomas Young in 1808 and especially Richard Bright in 1836.[84] The first report of elevated blood pressure in a patient without evidence of kidney disease was made by Frederick Akbar Mahomed (1849–1884).[86] However hypertension as a clinical entity came into being in 1896 with the invention of the cuff-based sphygmomanometer by Scipione Riva-Rocci in 1896.[87] This allowed blood pressure to be measured in the clinic. In 1905, Nikolai Korotkoff improved the technique by describing the Korotkoff sounds that are heard when the artery is ausculated with a stethoscope while the sphygmomanometer cuff is deflated.[85]

The concept of essential hypertension ('hypertonie essential') was introduced in 1925 by the physiologist Otto Frank to describe elevated blood pressure for which no cause could be found. In 1928, the term malignant hypertension was coined by physicians from the Mayo Clinic to describe a syndrome of very high blood pressure, severe retinopathy and adequate kidney function which usually resulted in death within a year from strokes, heart failure or kidney failure.[88] A prominent sufferer of severe hypertension was Franklin D. Roosevelt.[89] However, while the menace of severe or malignant hypertension was well recognised, the risks of more moderate elevations of blood pressure were uncertain and the benefits of treatment doubtful. Consequently, hypertension was often classified into "malignant" and "benign". In 1931, John Hay, Professor of Medicine at Liverpool University, wrote that "there is some truth in the saying that the greatest danger to a man with a high blood pressure lies in its discovery, because then some fool is certain to try and reduce it".[90][91] This view was echoed by the eminent US cardiologist Paul Dudley White in 1937, who suggested that "hypertension may be an important compensatory mechanism which should not be tampered with, even were it certain that we could control it".[92] Charles Friedberg's 1949 classic textbook "Diseases of the Heart",[93] stated that "people with 'mild benign' hypertension ... [defined as blood pressures up to levels of 210/100 mm Hg] ... need not be treated".[91] However the tide of medical opinion was turning: it was increasingly recognised in the 1950s that "benign" hypertension was not harmless.[94] Over the next decade increasing evidence accumulated from actuarial reports[85][95] and longitudinal studies, such as the Framingham Heart Study,[96] that "benign" hypertension increased death and cardiovascular disease, and that these risks increased in a graded manner with increasing blood pressure across the whole spectrum of population blood pressures. Subsequently the National Institutes of Health also sponsored other population studies, which additionally showed that African Americans had a higher burden of hypertension and its complications.[97]

Historically the treatment for what was called the "hard pulse disease" consisted in reducing the quantity of blood by blood letting or the application of leeches.[84] This was advocated by The Yellow Emperor of China, Cornelius Celsus, Galen, and Hipocrates.[84]

In the 19th and 20th centuries, before effective pharmacological treatment for hypertension became possible, three treatment modalities were used, all with numerous side-effects: strict sodium restriction (for example the rice diet [84]), sympathectomy (surgical ablation of parts of the sympathetic nervous system), and pyrogen therapy (injection of substances that caused a fever, indirectly reducing blood pressure).[84][97] The first chemical for hypertension, sodium thiocyanate, was used in 1900 but had many side effects and was unpopular.[84] Several other agents were developed after the Second World War, the most popular and reasonably effective of which were tetramethylammonium chloride and its derivative hexamethonium, hydralazine and reserpine (derived from the medicinal plant Rauwolfia serpentina). A major breakthrough was achieved with the discovery of the first well-tolerated orally available agents. The first was chlorothiazide, the first thiazide diuretic and developed from the antibiotic sulfanilamide, which became available in 1958;[84][98] it increased salt excretion while preventing fluid accumulation. A randomized controlled trial sponsored by the Veterans Administration comparing hydrochlorothiazide plus reserpine plus hydralazine versus placebo had to be stopped early in a high blood pressure group because those not receiving treatment developed many more complications and it was deemed unethical to withhold treatment from them. The study continued in people with lower blood pressures and showed that treatment even in people with mild hypertension more than halved the risk of cardiovascular death.[99] In 1975, the Lasker Special Public Health Award was awarded to the team that developed chlorothiazide.[97] The results of these studies prompted public health campaigns to increase public awareness of hypertension and promoted the measurement and treatment of high blood pressure. These measures appear to have contributed at least in part to the observed 50% fall in stroke and ischemic heart disease between 1972 and 1994.[97]

Soon more drugs became available to treat hypertension. The British physician James W. Black developed beta blockers in the early 1960s;[100] these were initially used for angina, but turned out to lower blood pressure. Black received the 1976 Lasker Award and in 1988 the Nobel Prize in Physiology or Medicine for his discovery.[97] The next class of antihypertensives to be discovered were calcium channel blockers. The first member was verapamil, a derivative of papaverine that was initially thought to be a beta blocker and used for angina, but then turned out to have a different mode of action and was shown to lower blood pressure.[97] The renin-angiotensin system was known to play an important role in blood pressure regulation, and angiotensin converting enzyme (ACE) inhibitors were developed through rational drug design. In 1977 captopril, an orally active agent, was described;[101] this led to the development of a number of other ACE inhibitors.[97] More recently angiotensin receptor blockers and renin inhibitors have also been introduced as antihypertensive agents.

Society and culture

Economics

High blood pressure is the most common chronic medical problem prompting visits to primary health care providers in USA. The American Heart Association estimated the direct and indirect costs of high blood pressure in 2010 as $76.6 billion.[102] Hypertension affects ≈76,400,000 US adults (≈34% of the US population) and African American adults have among the highest rates of hypertension in the world (44%).[102] In the US 80% of people with hypertension are aware of their condition, 71% take some antihypertensive medication, but only 48% of people aware that they have hypertension are adequately controlled.[102] Adequate management of hypertension can be hampered by inadequacies in the diagnosis, treatment, and/or control of high blood pressure.[103] Health care providers face many obstacles to achieving blood pressure control from their patients, including resistance to taking multiple medications to reach blood pressure goals. Patients also face the challenges of adhering to medicine schedules and making lifestyle changes. Nonetheless, the achievement of blood pressure goals is possible, and most importantly, lowering blood pressure significantly reduces the risk of death due to heart disease and stroke, the development of other debilitating conditions, and the cost associated with advanced medical care.,[104][105]

Awareness

Graph showing, prevalence of awareness, treatment and control of hypertension compared between the four studies of NHANES[80]

The World Health Organization has identified 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.[106] 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.[107]

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Translations:

Hypertension

Top

Dansk (Danish)
n. - for højt blodtryk

Nederlands (Dutch)
hypertensie, hoge bloeddruk

Français (French)
n. - hypertension

Deutsch (German)
n. - Hypertonie, Bluthochdruck

Ελληνική (Greek)
n. - (παθολ.) υπέρταση

Italiano (Italian)
ipertensione

Português (Portuguese)
n. - hipertensão (f) (Med.)

Русский (Russian)
высокое кровяное давление

Español (Spanish)
n. - hipertensión

Svenska (Swedish)
n. - hypertoni (för högt blodtryck)

中文(简体)(Chinese (Simplified))
高血压, 过度紧张

中文(繁體)(Chinese (Traditional))
n. - 高血壓, 過度緊張

한국어 (Korean)
n. - 고혈압, 긴장 항진(증)

日本語 (Japanese)
n. - 高血圧, 緊張亢進

العربيه (Arabic)
‏(الاسم) فرط ضغط الدم الشرياني خاصته‏

עברית (Hebrew)
n. - ‮לחץ דם גבוה‬


 
 

 

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