High Blood Pressure

High blood pressure, or hypertension, is the most common major health condition in the United States. It is one of the leading causes of heart attack, heart failure, stroke, kidney failure, and premature death. It also can damage parts of the circulatory system—including blood vessels in the heart, brain, eyes, and kidneys.

Sometimes called the "silent killer," high blood pressure is a disease that can go undetected for years. The higher the blood pressure or the longer it goes undiagnosed, the worse the outlook. More than 50 million Americans have high blood pressure. Of that number, an estimated one-third do not know they have the disease.

There has been remarkable progress in detecting, treating, and controlling high blood pressure. Recently, there has been a substantial increase in the number of individuals who are aware of their high blood pressure and who are being treated for it. At the same time, the incidences of coronary artery disease and stroke have significantly decreased, partially as a result of progress in the detection, treatment, and control of high blood pressure. Despite these efforts, most people with high blood pressure do not have adequately controlled blood pressure. Unfortunately, high blood pressure remains a serious medical problem.

Approximately 5 percent of cases of high blood pressure can be traced to underlying diseases, such as kidney disorders or conditions that cause narrowing of the arteries. This is called "secondary hypertension." But most cases have no known cause. This type is called "primary" or "essential" hypertension.


Risk Factors for High Blood Pressure

There are risk factors that indicate a predisposition for the development of high blood pressure. Among these risk factors are the following:

Family history—A family history of high blood pressure is a risk for hypertension.

Age—High blood pressure becomes more common among all people as they grow older. After all, nearly two-thirds of Americans aged 70 or older have the disease.

Sex—Although men and women are typically equally affected, women who use birth control pills and smoke cigarettes have a greater chance of having high blood pressure.

Race—As an example, high blood pressure is more common among blacks than whites.

You either have or don’t have the above risk factors. There are also other factors that increase your risk for high blood pressure which you can do something about:

• obesity—control your weight

• lack of exercise—get moving

• alcohol consumption—take control or abstain

• excessive salt (sodium) intake—cut down

Classification of High Blood Pressure

Systolic (mm Hg)

 

Diastolic (mm Hg)

Optimal*

120 or less

and

80 or less

Normal

129 or less

and

84 or less

High-normal

130-139

or

85-89

Hypertension

 

 

 

Stage 1f

140-159

or

90-99

Stage 2t

160-179

or

100-109

Stage 3t

180 or higher

or

110 or higher

*Optimal pressure with respect to cardiovascular risk.

fBased on the average of two or more readings taken at each of two or more visits after an initial screening.

Measuring Blood Pressure

Blood pressure is the force that the blood exerts on the artery walls as the heart pumps it through the body. The amount of force depends on various factors, including how hard the heart pumps and the volume of blood it pumps. Another factor is the amount of resistance blood encounters in the arteries—the thicker or more clogged the blood vessels, the greater the resistance. The elasticity of arteries also plays a role in blood pressure. The less elastic arteries are, the less they expand under the force of a heartbeat and the higher the resistance.

The standard way to measure blood pressure is in millimeters of mercury (mm Hg). This unit of measurement refers to how high the pressure inside the arteries is able to raise a column of mercury. Each blood pressure measurement has two numbers. The top number is the systolic blood pressure, or the highest pressure within the arteries that occurs during "systole," when the heart is contracting. The bottom number is the diastolic blood pressure, or the lowest pressure within the arteries that occurs during "diastole," when the heart is relaxed and filling with blood.

For most people, a blood pressure of 120/80 mm Hg or lower is considered healthy.

Effects of High Blood Pressure

Repeated blood pressure measurements that are more than 130/85 mm Hg indicate a potential for problems, a greater risk of progressing to definite high blood pressure, and the need to have regular blood pressure checks. A measurement of 140 systolic or more, 90 diastolic or more, or both indicates high blood pressure, which requires treatment. Recent guidelines stress the importance of treating to achieve a pressure less than 130/85. Indeed, treating to these lower levels of blood pressure further reduces the incidence of stroke, heart and kidney damage, and other vascular problems.

When high blood pressure occurs, it means that the force of the blood in the arteries is excessive and many health complications can occur (see illustration on page 55).

Heart

High blood pressure forces the heart to work harder than it should to pump blood to distant tissues and organs. Another way to understand blood pressure is to think of it as a weight or a load that the heart muscle must "push" against. Like any muscle, the heart gets larger with pushing heavy

*Optimal pressure with respect to cardiovascular risk. fBased on the average of two or more readings taken at each of two or more visits after an initial screening.

Eventually, the heart’s pumping efficiency decreases when the muscle can no longer adapt to the excessive workload that the high blood pressure demands. When this occurs, the heart muscle may weaken and the heart can fail.

Arteries

High blood pressure can also accelerate the development of plaque within the arteries, a condition known as atherosclerosis. With the narrowing of the artery walls, the risk of heart attack is increased. High blood pressure also can lead to bulges (aneurysms) in the arteries. If an aneurysm in a major artery ruptures, the results can be catastrophic and possibly fatal.

Brain

High blood pressure increases the risk of having a stroke, which occurs when a blood vessel within the brain either ruptures or is blocked.

Kidneys

The kidneys filter waste products from the blood and maintain proper blood minerals and blood volume. When these functions are impaired or compromised, so is their role in helping to maintain blood pressure. These effects can produce a destructive cycle that results in increasing blood pressure and a gradual failure of the kidneys to remove impurities from the blood.

Eyes

High blood pressure often causes problems with the eyes. Examination of the retina can reveal narrowing of the arteries, small hemorrhages, and accumulations of protein that have leaked from affected blood vessels (exudates). Although it is unusual for high blood pressure to impair vision, it can occur as a result of severe constriction of the retinal arteries and swelling (edema) of the retina during episodes of increased blood pressure. Treating the high blood pressure is the only way to reverse this vision loss.

Treating High Blood Pressure

Fortunately for many people, high blood pressure is preventable. Even those who already have high blood pressure or are at increased risk may be able to reduce the number and doses of medications needed to control it and minimize other health complications by the following lifestyle modifications.

High blood pressure can damage vital organs and result in many life-threatening medical problems.

High blood pressure can damage vital organs and result in many life-threatening medical problems.  

Lose weight—If you are overweight, losing weight is the most effective non-drug method for lowering blood pressure. A weight loss of as little as 10 pounds can significantly reduce blood pressure in many overweight people with high blood pressure. In some people, weight loss alone is sufficient to avoid the need for blood pressure medication.

Exercise—When compared with more active and fit peers, sedentary individuals with normal blood pressure have a 20 to 50 percent increased risk for development of high blood pressure. Regular aerobic exercise such as walking or biking for 30 to 45 minutes most days of the week is a very effective means of lowering blood pressure.

Limit alcohol—Excessive alcohol intake is a risk factor for high blood pressure and stroke. It also can interfere with the effects of blood pressure medications. Men who drink should limit their intake to no more than 2 drinks a day; women should have no more than 1 drink daily.

Do not smoke—Smoking a cigarette temporarily increases blood pressure for up to 30 minutes. Smoking is also a major risk factor for cardiovascular disease. Everyone, especially people with high blood pressure, needs to quit smoking or never start.

Limit or avoid high-sodium foods—A high intake of sodium in the diet increases blood pressure in some people. The average American consumes about 4,000 milligrams or more of sodium a day. People with high blood pressure should limit their sodium intake to less than 2,400 milligrams a day, and many experts recommend the same limit for everyone.

The Combination Diet From the DASH Study

This eating plan is from the "Dietary Approaches to Stop Hypertension" (DASH) study from the National Institutes of Health. This diet is rich in vegetables, fruits, and low-fat dairy foods and low in saturated fat, total fat, and cholesterol. It is also high in potassium, calcium, and magnesium.

Food Group

Daily Servings

Serving Sizes

Significant Nutrients in Each Food Group

Grains and grain products (emphasis on whole grains)

7-8

1 slice bread 1/2 cup dry cereal 1/2 cup cooked rice, pasta, or cereal

Energy and fiber

Vegetables

4-5

1 cup leafy vegetable 1/2 cup cooked vegetable 6 ounces vegetable juice

Potassium, magnesium, and fiber

Fruits

4-5

1 medium fruit 1/2 cup fresh, frozen,

or canned fruit 1/4 cup dried fruit 6 ounces 100% juice

Potassium, magnesium, and fiber

Low-fat or nonfat dairy products

2-3

8 ounces milk 1 cup yogurt 1.5 ounces cheese

Calcium and protein

Lean meats, poultry, fish

2 or less

3 ounces cooked meats, poultry, or fish

Protein and magnesium

Nuts, seeds, and legumes

4-5 per week

1.5 ounces (1/3 cup) nuts 2 tablespoons (1/2 ounce) seeds

1/2 cup cooked legumes

Magnesium, potassium, protein, and fiber; high in calories

Note: This plan provides approximately 2,000 calories. The number of daily servings from a food group should vary with individual needs.

Follow a balanced nutrition program—A low-fat, high-fruit and vegetable diet can lower blood pressure impressively, all by itself. A large percentage of people with high blood pressure may be able to decrease their need for blood pressure medication if they follow the recommendations of the Food Guide Pyramid. A diet following this plan promotes weight loss and is high in minerals such as calcium, potassium, and magnesium, which have been associated with lower blood pressure.

The National Heart, Lung and Blood Institute recently sponsored a study testing the effects of different diets on blood pressure, called the "DASH" (Dietary Approaches to Stop Hypertension) study. Participants in the study ate one of three diets: an average American diet, a diet rich in fruits and vegetables, or a "combination" diet that emphasized fruits, vegetables, and low-fat dairy products and was low in fat and saturated fat. Sodium consumption was the same in all three diets. Participants were asked to limit obviously salty food, to rinse canned vegetables, and to not add extra salt to food.

Both the fruit-and-vegetable diet and the "combination" diet lowered blood pressure. However, the combination diet was the most effective. Within that group, people with above-normal blood pressure (more than 129/80 mm Hg) and those with high blood pressure (more than 140/90 mm Hg) experienced reductions of their blood pressure similar to those achieved with some blood pressure medications.

Researchers believe that people following the combination diet fared better because of the low saturated fat and high fruit and vegetable mixture that provided adequate potassium, magnesium, and calcium. For people with normal blood pressure, the combination diet may help to avoid blood pressure problems. If blood pressure is only slightly increased, following this diet may actually eliminate the need for medication. For people with severe high blood pressure, the diet may allow reduction in blood pressure medication (see sidebar: The Combination Diet From the DASH Study, page 56).

When Medications Are Needed

When lifestyle changes alone are not effective for lowering high blood pressure, medications may be required. Medications vary in the way they control blood pressure. Some types help the kidneys to eliminate sodium and water, some make the heart beat more slowly and less forcefully, and others enable the blood vessels to relax and decrease the resistance to blood flow. Your physician will determine which drug or combination of drugs is best suited for you.

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