If you're healthy, your arteries are muscular and elastic. They stretch when your heart pumps blood through them. How much they stretch depends on how much force the blood exerts.

Your heart beats about 60 to 80 times a minute under normal conditions. Your blood pressure rises with each heartbeat and falls when your heart relaxes between beats. Your blood pressure can change from minute to minute, with changes in posture, exercise or sleeping, but it should normally be less than 120/80 mm Hg for an adult. Blood pressure that stays between 120-139/80-89 is considered prehypertension and above this level (140/90 mm Hg or higher) is considered high (hypertension). Your doctor may take several readings over time before deciding whether your blood pressure is high.

What do blood pressure numbers indicate?

• The higher (systolic) number represents the pressure while the heart is beating.
• The lower (diastolic) number represents the pressure when the heart is resting between beats.

The systolic pressure is always stated first and the diastolic pressure second. For example: 117/76 (117 over 76); systolic = 117, diastolic = 76.

Am I risk?

Factors that contribute to high blood pressure

Medical science doesn't understand why most cases of high blood pressure occur, so it's hard to say how to prevent it. However, we do know of several factors that may contribute to high blood pressure and put you at increased risk for heart attack and stroke.

Controllable risk factors

• Obesity — People with a body mass index (BMI) of 30.0 or higher are more likely to develop high blood pressure.
• Eating too much salt — A high sodium intake increases blood pressure in some people.
• Drinking too much alcohol — Heavy and regular use of alcohol can increase blood pressure dramatically.
• Lack of physical activity — An inactive lifestyle makes it easier to become overweight and increases the chance of high blood pressure.
• Stress — This is often mentioned as a risk factor, but stress levels are hard to measure, and responses to stress vary from person to person.

Uncontrollable risk factors

• Race — Blacks develop high blood pressure more often than whites, and it tends to occur earlier and be more severe.
• Heredity — If your parents or other close blood relatives have high blood pressure, you're more likely to develop it.
• Age — In general, the older you get, the greater your chance of developing high blood pressure. It occurs most often in people over age 35. Men seem to develop it most often between age 35 and 55. Women are more likely to develop it after menopause.

Why should I care?

High blood pressure is the No. 1 modifiable risk factor for stroke. It also contributes to heart attacks, heart failure, kidney failure and atherosclerosis (fatty buildups in arteries). In some cases, it can cause blindness. Recent studies show that in adults 40–89, the risk of death from heart disease and stroke begins to rise at blood pressures as low as 115/75. The risk doubles for each increased increment of 20 mmHg in systolic blood pressure or 10 mm Hg in diastolic blood pressure. Elevated systolic blood pressure indicates a more important risk than diastolic blood pressure except in patients younger than 50. The relationship of blood pressure levels to the risk of cardiovascular disease is continuous, consistent and independent of other risk factors. The higher the blood pressure, the greater is the chance for heart attack, heart failure, stroke and kidney disease.

In clinical trials it has been shown that by lowering blood pressure to acceptable levels:

• Stroke incidence can be reduced by an average of 35–40 percent.
• Heart attack incidence can be reduced by an average of 20–25 percent.
• Heart failure incidence can be reduced by an average of more than 50 percent.

If you have high blood pressure, follow your doctor's advice. Most high blood pressure can't be cured, but it usually can be controlled. And its effects can be prevented or reduced — if it's treated and controlled early, and kept under control.

What can I do?

High blood pressure is a lifelong disease. It can usually be controlled but not cured. Once you begin to manage it and start a treatment program, maintaining a lower blood pressure is easier. By controlling your high blood pressure, you'll lower your risk of diseases like stroke, heart attack, heart failure and kidney disease. You can do it!

The first thing to do is to have your blood pressure checked. If you have high blood pressure, you can do a lot to reduce it. Work with your doctor to determine the best treatment for you.

• It may include a reducing the fat (particularly saturated fat) in your diet, eating less salt, and changing your lifestyle by losing weight and getting regular physical activity.
• Quitting smoking is also important to reduce your overall risk for heart attack and stroke. 
• Your doctor may recommend reducing how much alcohol you drink.
• Many medicines also can help reduce and control high blood pressure. Your doctor will decide whether you need medicine in addition to dietary and lifestyle changes.

Be sure to look at our patient education sheets on high blood pressure. These can be printed out and taken to your physician. There are spaces for you to ask questions and for your physician to write special instructions for you.

What is ahigh Blood Pressure?

Blood pressure is the force in the arteries when the heart beats (systolic pressure) and when the heart is at rest (diastolic pressure). It's measured in millimeters of mercury (mm Hg). High blood pressure (or hypertension) is defined in an adult as a blood pressure greater than or equal to 140 mm Hg systolic pressure or greater than or equal to 90 mm Hg diastolic pressure.

High blood pressure directly increases the risk of coronary heart disease (which leads to heart attack) and stroke, especially along with other risk factors.

High blood pressure can occur in children or adults, but it's more common among people over age 35. It's particularly prevalent in African Americans, middle-aged and elderly people, obese people, heavy drinkers and women who are taking birth control pills. It may run in families, but many people with a strong family history of high blood pressure never have it. People with diabetes mellitus, gout or kidney disease are more likely to have high blood pressure, too.

American Heart Association recommended blood pressure levels