Overview

Definition

Blood pressure is the force of blood in your arteries as the heart beats and relaxes. When you get a blood pressure reading from your doctor, you get two numbers. The top number is called the systolic number, which measures your heartbeats. The bottom number is called the diastolic pressure, which measures how much the heart rests in between beats.

High blood pressure, also known as hypertension, causes your heart and arteries to work harder. This is OK in the short run, but, if left unchecked over the years, your heart may become enlarged and other organs such as your kidneys can be affected. Your risk of stroke, congestive heart failure, kidney failure and heart attack increases. High blood pressure along with obesity, smoking, high blood cholesterol levels or diabetes greatly increases the risk of a heart attack or stroke.

Your heart beats about 100,000 times a day. That's 100,000 chances for hypertension to damage your blood vessels and body.

Your blood pressure is considered high if you have a systolic blood pressure greater than 140 or a diastolic pressure greater than or equal to 90. A healthy adult has a blood pressure of less than 120/80. Each time your blood pressure goes up by 20 over 10, you double your risk of cardiovascular disease. The higher you go, the higher your risk. Your risk starts to double starting at 115/ 75. That means if your blood pressure is 135/90, your risk of a heart attack is double that of someone with a blood pressure of 115/75.

Blood pressure is not static. It can change if you are stressed, sleeping, exercising or even drinking caffeine. This is why your doctor needs to take several readings before making a diagnosis.

Children and young adults can develop high blood pressure, although it is most common in people older than 35. One in five Americans and one in four adult Americans has high blood pressure, and nearly one-third of them don't know they have it. About 65 million Americans older than 6 have high blood pressure. Even people who are on medication to treat it may not have their blood pressure adequately controlled. High blood pressure affects more than 40 percent of African Americans, who are affected more than any other ethnic group.

Prognosis

High blood pressure does not have a cure. However, it can be controlled and even reduced with lifestyle modifications and medication. Your doctor will urge you to adopt healthy habits and may prescribe medications, including diuretics (water pills). You must follow your doctor's orders. Your doctor will tell you how often you should have your blood pressure checked. Many doctors routinely check it each time you come in for a visit.

More on Hypertension

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This article was reviewed and updated June 2007.