Multiple: Hypertension

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Hypertension, or high blood pressure (HBP), is a condition in which a person's blood pressure is higher than is healthy over a period of time. Blood pressure normally rises and falls over the course of a day; it also

rises when a person is anxious or is exercising. Doctors usually take blood pressure readings during two different office visits before diagnosing hypertension.

Blood pressure is measured in millimeters of mercury (mm Hg) because the sphygmomanometer—the device most commonly used to measure blood pressure—contains a column of mercury that rises and falls as the doctor inflates and deflates a cuff around the patient'sarm.Thefirst of two numbers in a blood pressure measurement is the systolic blood pressure. It is the peak blood pressure in the patient's arteries. The second measurement is the diastolic blood pressure and represents the lowest blood pressure, which occurs when the heart is resting between beats.

Doctors use the following values, measured in millimeters of mercury (mm Hg), when evaluating a patient for hypertension:

• Normal blood pressure: systolic below 120 mm Hg, diastolic below 80.
• Pre-hypertension: systolic between 120 and 139 mm Hg, diastolic between 80 and 99.
• Stage 1 hypertension: systolic between 140 and 159 mm Hg, diastolic between 90 and 99.
• Stage 2 hypertension: systolic 160 mm Hg or higher, diastolic 100 or higher.

Doctors also distinguish between primary (or essential) hypertension and secondary hypertension. Essential hypertension, which accounts for about 95 percent of cases in American adults, is high blood pressure that develops without any apparent cause. Secondary hypertension, which accounts for the remaining 5 percent, is caused by other diseases or conditions, including pregnancy, abnormalities in the shape of the aorta, kidney disease, alcoholism, thyroid disease, the use of birth control pills, and tumors of the adrenal gland.

Description

Hypertension is considered a silent disease because a person can have it for years without any noticeable symptoms. Although some people develop nosebleeds, headaches, dizziness, nausea, or changes in their vision as a result of hypertension, the majority of those diagnosed with high blood pressure do not know they have a problem until their doctor checks their blood pressure during a routine physical exam. Sadly, some

people do not know they have high blood pressure until they have a stroke or heart attack.

Untreated hypertension can damage the heart and other organs:

• High blood pressure can lead to heart failure by causing the heart to enlarge or grow weaker.
• Hypertension can lead to stroke by causing a bulge or weak spot along the wall of an artery known as an aneurysm.
• Blood vessels in the eye can burst or bleed as a result of high blood pressure, leading to loss of vision.
• High blood pressure can cause the blood vessels in the kidneys to become too narrow, leading eventually to kidney failure. Narrowing of the blood vessels in the heart may eventually cause a heart attack.

Demographics

Hypertension is almost entirely a disorder of adults; it affects only 1–3 percent of children and teenagers. About 35 percent of adults in the United States have high blood pressure. Worldwide, hypertension is a leading cause of illness and death; it is the most important factor that people can control in regard to their risk of heart failure, heart disease, stroke, and kidney failure.

Risk factors for hypertension include:

• Age: As people get older, their arteries tend to stiffen, thus contributing to high blood pressure.
• Race: African Americans develop hypertension at higher rates than members of other races in the United States. They also develop high blood pressure at younger ages.
• Sex: Men are more likely to develop hypertension than women.
• Obesity: People with a body mass index (BMI) over thirty are at increased risk of high blood pressure.
• Family history: Hypertension is known to run in families.
• Lack of exercise.
• Drugs of abuse: Cocaine, amphetamines, and heavy alcohol use all increase a person's risk of hypertension.

Causes and Symptoms

The causes of essential hypertension are not known.

Causes of secondary hypertension include:

• Chronic kidney disease
• Tumors or other diseases affecting the adrenal gland
• An unusually narrow aorta (Some people are born with this condition.)
• Pregnancy
• Use of birth control pills
• Thyroid disorders

Diagnosis

Hypertension is diagnosed in the doctor's office by the use of a sphygmo-manometer. The doctor places a cuff around the patient's upper arm and inflates it while listening through a stethoscope. The cuff is inflated until the air pressure squeezes the large artery in the upper arm shut. The doctor then releases pressure in the cuff until he or she can start to hear the sounds of the patient's pulse. This is the systolic pressure. The doctor then continues to release pressure until the sounds disappear. This second reading is the diastolic pressure.

In addition to measuring the patient's blood pressure, the doctor may order additional tests to look for possible causes of the hypertension or signs of damage to other organs:

• Blood and urine tests. These can be done to look for evidence of kidney or thyroid disease or to measure the levels of cholesterol in the patient's blood.
• X-ray studies of the chest or the kidneys.
• Electrocardiogram (ECG or EKG). This test measures the electrical activity of the heart and may be done to evaluate the condition of the patient's heart muscle.

Treatment

There is no cure for hypertension. Treatment for the disorder comprises a combination of lifestyle changes and medications. Some people can lower their blood pressure by losing weight and getting more exercise, but most need to take medications to keep their blood pressure within the normal range.

The doctor may prescribe one or a combination of medications to control the patient's blood pressure. In most cases the patient will be asked to see the doctor every three to four months to see whether the drugs or their dosage levels need to be adjusted. Although these drugs can produce side effects, the patient should not stop taking them without consulting the doctor. The various types of drugs given to control hypertension include:

• Diuretics. Sometimes called water pills, diuretics increase salt and urine output. They are often prescribed in combination with other types of pills.
• ACE inhibitors. These drugs work to lower blood pressure by blocking the production of a chemical that causes blood vessels to tighten.
• Calcium channel blockers. These drugs work by reducing the force of the contraction of the heart muscle.
• Beta blockers. Drugs in this group slow down the heart rate. They are often prescribed for people who have had a heart attack or a history of heart disease.
• Vasodilators. These drugs cause blood vessels to open up, which lowers blood pressure. They may be given intravenously if the patient's blood pressure has risen very high very quickly.

• Alpha blockers. Drugs in this group block nerve impulses that cause blood vessels to tighten up. The blood can then move more freely through the blood vessels, thus lowering blood pressure.

Prognosis

Most patients with hypertension can keep their blood pressure at a healthy level provided they follow their doctor's recommendations about diet and exercise and take their blood pressure medications. They should watch their blood pressure carefully as they age because hypertension tends to get worse as people get older. Even mild hypertension, if untreated, increases a person's risk of heart disease by 30 percent and kidney damage by 50 percent within eight to ten years after it starts.

Prevention

Hypertension is a lifelong disorder that requires long-term commitment to healthy lifestyle changes and regular use of prescribed medications.

Specific lifestyle changes recommended by the National Institutes of Health (NIH) for controlling hypertension include:

• Eating a healthful diet. A good place to start is the Dietary Approaches to Stop Hypertension (DASH) diet, which emphasizes eating more fruits, vegetables, and low-fat dairy products, and cutting back on salt and alcohol.
• Get regular physical exercise, preferably at least thirty minutes a day.
• Stop smoking (or do not start).
• Learn to manage emotional stress effectively; relaxation techniques, biofeedback, meditation, or yoga work well for many people.
• Lose weight if the doctor recommends it.
• Avoid cocaine, heavy drinking, and other recreational drugs that raise blood pressure.
• Have blood pressure checked regularly and take all medications for hypertension on a daily basis even if you feel fine.

The Future

The rates of hypertension in all developed countries are expected to rise over the next several decades as populations get older and the rates of obesity continue to increase. A major difficulty in treating hypertension is that

many people do not know they have it, and others stop taking their blood pressure medications because they dislike the side effects or do not think their drugs are necessary. As of 2008, only 20 percent of Americans diagnosed with high blood pressure were following their doctors' recommendations and getting adequate treatment. Researchers are looking at patient education programs and behavioral approaches to treatment as much as new drugs and new methods of screening for hypertension.

SEE ALSO Diabetes; Heart attack; Heart failure; Obesity; Stroke

WORDS TO KNOW

Aneurysm: A weak or thin spot on the wall of an artery.

Aorta: The large artery that carries blood away from the heart to be distributed to the rest of the body.

Diastolic blood pressure: The blood pressure when the heart is resting between beats.

Essential hypertension: High blood pressure that is not caused by medications, pregnancy, or another disease.

Sphygmomanometer: The device used to measure blood pressure. It consists of an inflatable cuff that compresses an artery in the arm. The doctor listens through a stethoscope as the air pressure in the cuff is released in order to measure the blood pressure.

Systolic blood pressure: The blood pressure at the peak of each heartbeat.

For more information

BOOKS

Rubin, Alan L. High Blood Pressure for Dummies, 2nd ed. Indianapolis, IN: Wiley Publishing, 2007.

Sheps, Sheldon G., ed. Mayo Clinic 5 Steps to Controlling High Blood Pressure. Rochester, MN: Mayo Clinic, 2008.

Townsend, Raymond R. 100 Questions and Answers about High Blood Pressure (Hypertension). Sudbury, MA: Jones and Bartlett Publishers, 2008.

PERIODICALS

Sabo, Eric. “Practical Blood Pressure Advice, Too Often Shelved for Convenience.” New York Times, April 4, 2008. Available online at http://health. nytimes.com/ref/health/healthguide/esn-hypertension-ess.html (accessed on September 22, 2008). This is an article about the DASH diet and limiting salt intake in controlling hypertension.

WEB SITES

American Academy of Family Physicians (AAFP). High Blood Pressure: Things You Can Do to Lower Yours. Available online at http://www.familydoctor.org/online/famdocen/home/common/heartdisease/risk/092.html (updated November 2006; accessed on September 22, 2008).

American Heart Association. What Is High Blood Pressure? Available online at http://www.americanheart.org/presenter.jhtml?identifier=2112 (updated April 18, 2008; accessed on September 22, 2008).

Centers for Disease Control and Prevention (CDC). About High Blood Pressure. Available online at http://www.cdc.gov/bloodpressure/about.htm (updated August 2007; accessed on September 22, 2008).

eMedicine Health. High Blood Pressure. Available online at http://www.emedicinehealth.com/high_blood_pressure/article_em.htm (accessed on September 22, 2008).

National Heart, Lung, and Blood Institute (NHLBI). What Is High Blood Pressure? Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/Hbp/HBP_WhatIs.html (updated August 2008; accessed on September 22, 2008).

National Heart, Lung, and Blood Institute (NHLBI). In Brief: Your Guide to Lowering Your Blood Pressure with DASH. Available online in PDF format at http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/dash_brief.pdf (updated December 2006; accessed on September 22, 2008). This is a six-page pamphlet about the DASH diet with sample menus and a calorie guide.

National Library of Medicine (NLM). Essential Hypertension. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/hypertension/htm/index.htm (accessed on September 22, 2008). This is an online tutorial with voiceover; viewers have the option of a self-playing version, an interactive version with questions, or a text version.

TeensHealth. Hypertension (High Blood Pressure). Available onine at http://www.kidshealth.org/teen/diseases_conditions/heart/hypertension.html (updated August 2008; accessed on September 22, 2008).