Hypertension: your questions answered.

Q: What is blood pressure?(*)

A: When your heart beats (contracts), it squeezes blood into the arteries, creating pressure in them. This pressure (blood pressure) causes the blood to flow to all parts of the body. For most adults, a blood pressure reading that's less than 140/90 mm. Hg indicates little cause for concern.

Q: What is hypertension?(*)

A: Arterioles, smaller vessels that branch off from the arteries, regulate your blood pressure. It's similar to how a nozzle regulates the water pressure in a hose. If the nozzle is wide open, it takes relatively little pressure to force the water through the hose, but if the nozzle is partially shut (or you clamp your thumb over the opening of the hose), the water pressure in the hose increases.

The same applies in your blood vessels. If for some reason your arterioles are narrowed, it's harder for the blood to pass through them. When that happens, the result is that your blood pressure rises and your heart works harder. If the pressure in your arteries increases to 140/90 or more and stays there, you have high blood pressure, also called hypertension.

About 90 to 95 percent of the cases of high blood pressure have no known cause. This form is called primary high blood pressure. Although you can control it, there's no known cure.

Q: What causes hypertension?(*)

A: Although researchers haven't discovered specific causes, they have pinpointed some factors that increase the chance that a person will develop high blood pressure. These predisposing factors include heredity, sex, age, race, obesity, and sensitivity to sodium. Other related factors include heavy alcohol consumption, the use of oral contraceptives, and a sedentary lifestyle.

Q: Who is most likely to develop hypertension?([dagger])

A: People with a family history of high blood pressure, people over age 35, and African-Americans.

African-Americans with a family history of hypertension are most likely to develop it. One in four Americans have hypertension, but between 33 and 50 percent of all African-Americans have hypertension. It's at least twice as common in Blacks as in Whites. It also starts at a younger age in African-Americans.

Q: Could this be because of the high-fat diets of some African-Americans?([dagger])

A: Diet is a factor that affects everyone. At Howard University research is under way to try to determine the cause of high blood pressure and the factors that may be playing a major role. It could be that some African Americans have a genetic background that can make them vulnerable to hypertension when they are exposed to certain environmental factors, including diet, obesity, inactivity, stress, etc.

Q: How do you treat hypertension?(*)

A: Most treatments for high blood pressure rely on some combination of diet to lose weight, exercise, and medication to bring blood pressure under control.

Q: What happens if you don't treat hypertension?([dagger])

A: The most common results of untreated hypertension are kidney failure, strokes, heart failure, heart attack, and thickening of the heart. In African-Americans who fail to treat hypertension, the chance of kidney failure is 4 to 18 times higher than for anyone else.

Howard University is doing a study to find better ways to control hypertension to prevent the development of kidney failure. The study, African-American Study of Kidney Disease (AASK), is funded by the National Institutes of Health (NIH).

Q: If stress is a factor that contributes to hypertension, can stress reduction lower hypertension?([dagger])

A: It's not proven that controlling stress alone will lower blood pressure. You must control the other factors also--diet, weight, etc. And these all by themselves will not control hypertension. You need medication.

Q: Why aren't people aware that they have high blood pressure?([dagger])

A: There are usually no symptoms. Some people think you get headaches. People with hypertension do not get headaches. The best way to find out is to get your blood pressure checked twice a year beginning at age 20.

(*) About Blood Pressure, American Heart Association.

([dagger]) Otelio Randall, M.D., is a professor of medicine and physiology and biophysics and the director of hypertension at Howard University in Washington, D.C. He is in charge of the research on hypertension and the AASK study.