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What Is Blood Pressure?

Blood pressure is the force of blood against the walls of arteries. Blood pressure is recorded as two numbers—the systolic pressure (as the heart beats) over the diastolic pressure (as the heart relaxes between beats). The measurement is written one above or before the other, with the systolic number on top and the diastolic number on the bottom. For example, a blood pressure measurement of 120/80 mmHg (millimeters of mercury) is expressed verbally as "120 over 80."

Normal blood pressure is less than 120 mmHg systolic and less than 80 mmHg diastolic.

High Blood Pressure

High blood pressure increases your chance (or risk) for getting heart disease and/or kidney disease, and for having a stroke. It is especially dangerous because it often has no warning signs or symptoms. Regardless of race, age, or gender, anyone can develop high blood pressure. It is estimated that one in every four American adults has high blood pressure. Once high blood pressure develops, it usually lasts a lifetime. You can prevent and control high blood pressure by taking action.

In this section you will learn more about what high blood pressure is and what it does inside the body.

 

What Are High Blood Pressure and Prehypertension?

Blood pressure is the force of blood against the walls of arteries. Blood pressure rises and falls during the day. When blood pressure stays elevated over time, it is called high blood pressure.

The medical term for high blood pressure is hypertension. High blood pressure is dangerous because it makes the heart work too hard and contributes to atherosclerosis (hardening of the arteries). It increases the risk of heart disease and stroke, which are the first- and third-leading causes of death among Americans. High blood pressure also can result in other conditions, such as congestive heart failure, kidney disease, and blindness.

A blood pressure level of 140/90 mmHg or higher is considered high. About two-thirds of people over age 65 have high blood pressure. If your blood pressure is between 120/80 mmHg and 139/89 mmHg, then you have prehypertension. This means that you don't have high blood pressure now but are likely to develop it in the future. You can take steps to prevent high blood pressure by adopting a healthy lifestyle.

Those who do not have high blood pressure at age 55 face a 90 percent chance of developing it during their lifetimes. So high blood pressure is a condition that most people have at some point in their lives.

Both numbers in a blood pressure test are important, but for people who are 50 or older, systolic pressure gives the most accurate diagnosis of high blood pressure. Systolic pressure is the top number in a blood pressure reading. It is high if it is 140 mmHg or above.

 

What is systolic blood pressure?

Systolic pressure is the force of blood in the arteries as the heart beats. It is shown as the top number in a blood pressure reading. High blood pressure is 140 and higher for systolic pressure. Diastolic pressure does not need to be high for you to have high blood pressure. When that happens, the condition is called "isolated systolic hypertension," or ISH.

Is isolated systolic high blood pressure common?

Yes. It is the most common form of high blood pressure for older Americans. For most Americans, systolic blood pressure increases with age, while diastolic increases until about age 55 and then declines. About 65 percent of hypertensives over age 60 have ISH. You may have ISH and feel fine. As with other types of high blood pressure, ISH often causes no symptoms. To find out if you have ISH — or any type of high blood pressure — see your doctor and have a blood pressure test. The test is quick and painless.

Is isolated systolic high blood pressure dangerous?

Any form of high blood pressure is dangerous if not properly treated. Both numbers in a blood pressure test are important, but, for some, the systolic is especially meaningful. That's because, for those persons middle aged and older, systolic pressure gives a better diagnosis of high blood pressure.

If left uncontrolled, high systolic pressure can lead to stroke, heart attack, congestive heart failure, kidney damage, blindness, or other conditions. While it cannot be cured once it has developed, ISH can be controlled.

Clinical studies have proven that treating a high systolic pressure saves lives, greatly reduces illness, and improves the quality of life. Yet, most Americans do not have their high systolic pressure under control.

Does it require special treatment?

Treatment options for ISH are the same as for other types of high blood pressure, in which both systolic and diastolic pressures are high. ISH is treated with lifestyle changes and/or medications. The key for any high blood pressure treatment is to bring the condition under proper control. Blood pressure should be controlled to less than 140/90 mmHg. If yours is not, then ask your doctor why. You may just need a lifestyle or drug change, such as reducing salt in your diet or adding a second medication.

 

What is diastolic blood pressure?

Diastolic pressure is the force of blood in the arteries as the heart relaxes between beats. It's shown as the bottom number in a blood pressure reading.

The diastolic blood pressure has been and remains, especially for younger people, an important hypertension number. The higher the diastolic blood pressure the greater the risk for heart attacks, strokes and kidney failure. As people become older, the diastolic pressure will begin to decrease and the systolic blood pressure begins to rise and becomes more important. A rise in systolic blood pressure will also increase the chance for heart attacks, strokes, and kidney failure. Your physician will use both the systolic and the diastolic blood pressure to determine your blood pressure category and appropriate prevention and treatment activities.

Why Is High Blood Pressure Important?

High blood pressure is dangerous because it makes the heart work too hard. It also makes the walls of the arteries hard.

High blood pressure increases the risk for heart disease and stroke, the first- and third-leading causes of death for Americans. High blood pressure can also cause other problems, such as heart failure, kidney disease, and blindness.

 

Risk Factors for heart disease and stroke

Risk factors are behaviors or conditions that can increase your chances of developing a disease. For instance, high blood pressure is a risk factor for heart disease and stroke.

There are other risk factors for heart disease and stroke. Most can be modified, though some cannot. The more risk factors you have, the greater your chances of developing disease. So it is important to take steps to prevent or control these risk factors.

Heart disease and stroke risk factors that can be controlled are:

High blood pressure (hypertension)
Abnormal cholesterol
Tobacco use
Diabetes
Overweight
Physical inactivity

Risk factors beyond your control are:

Age (55 years and older for men and 65 years or older for women)
Family history of early heart disease (having a mother or sister who has been diagnosed with heart disease before age 65, or a father or brother diagnosed before age 55) or family history of stroke

High Blood Pressure Detection

You can find out if you have high blood pressure by having your blood pressure checked regularly. Most doctors will diagnose a person with high blood pressure on the basis of two or more readings, taken on several occasions. A consistent blood pressure reading of 140/90 mmHg or higher is considered high blood pressure, another term for hypertension.

Some people experience high blood pressure only when they visit the doctor's office. This condition is called "white-coat hypertension." If your doctor suspects this, you may be asked to monitor your blood pressure at home or asked to wear a device called an ambulatory blood pressure monitor. This device is usually worn for 24 hours and can take blood pressure every 30 minutes. In this section you will learn more about diagnosing high blood pressure.

 

Prevention

You can take steps to prevent high blood pressure by adopting a healthy lifestyle. These steps include maintaining a healthy weight; being physically active; following a healthy eating plan, that emphasizes fruits, vegetables, and lowfat dairy foods; choosing and preparing foods with less salt and sodium; and, if you drink alcoholic beverages, drinking in moderation. In this section you will learn more about healthy lifestyle habits for preventing and controlling high blood pressure.

Following a Healthy Eating Pattern
Reducing Salt and Sodium in Your Diet
Maintaining a Healthy Weight
Being Physically Active
Limiting Alcohol Intake
Quitting Smoking

 

Treatment of High Blood Pressure

It is important to take steps to keep your blood pressure under control. The treatment goal is blood pressure below 140/90 and lower for people with other conditions, such as diabetes and kidney disease. Adopting healthy lifestyle habits is an effective first step in both preventing and controlling high blood pressure. If lifestyle changes alone are not effective in keeping your pressure controlled, it may be necessary to add blood pressure medications. In this section you will learn about blood pressure-lowering lifestyle habits and blood pressure medications.