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Personal Business: Health
HYPERTENSION: TAKE HEART
It doesn't hurt, it doesn't feel bad. Yet it leads to the nation's No. 1 cause of death. High blood pressure, or hypertension, increases the risk of dying from cardiovascular diseases and strokes. These combined kill about 1 million people a year--twice as many as cancer.
Despite decades of research, hypertension remains an enigma. Even though about one in five Americans has it, researchers don't know what causes it, and controversy rages over what affects it. In the meantime, doctors have been controlling hypertension with a growing armory of drugs, and the death toll has been steadily declining, by 30% in the past decade. But now, physicians are starting to reconsider the drug-intensive approach to treatment. They are discovering that many patients respond just as well to changes in living habits as to lifelong drug use.
BIGHEARTED. Blood pressure embraces two different measures: The top, or systolic, reading represents the force of blood against the artery walls as the heart beats, while the bottom, or diastolic, figure relates to the pressure when the heart rests and refills between beats. A blood pressure greater than 140/90 is considered high.
Prolonged hypertension can burden the heart, causing it to enlarge and malfunction. It can also damage the arteries that feed the heart muscle and the brain, leading to heart attacks or strokes. According to the American Heart Assn. (AHA), people with uncontrolled hypertension are three times as likely to develop heart disease, six times as likely to develop congestive heart failure, and seven times as likely to suffer a stroke as people with controlled hypertension.
Many conditions seem to accompany or contribute to the most common form of high blood pressure, called essential hypertension. "Hypertension is turning out to be a lot more complicated than we thought," says Allen Cowley Jr., head of the AHA's research council on blood pressure. "It is merely a piece of a much larger disease process."
Part of that process involves the endothelium, or inner lining of the arteries. Cells in this lining were long viewed as mere passageways for blood, but they are now known to release factors that regulate blood-vessel constriction, relaxation, and thickening. And they create new capillaries and tiny blood vessels that are constantly being destroyed and then replaced. "There's a flurry of activity to identify these factors and develop ways to turn them on and off," says Cowley. These same cells become damaged in atherosclerosis, or hardening of the arteries. As a result, cholesterol, platelets, and cellular debris collect in arteries, narrowing them and forcing the heart to work harder.
Another piece of the hypertension puzzle surfaced this year when Dr. Richard Lifton of Brigham & Women's Hospital in Boston discovered a genetic mutation responsible for an early and virulent form of hypertension. Scientists are starting to close in on a complex of genes that may cause essential hypertension in rats. And further evidence points to a genetic cause. Hypertension runs in families and is affected by sex and race: Men suffer from it more than women do, especially before the age of 55, and blacks get it more often and more severely than whites.
Environmental factors also play a role, though how much is debated. Yet most doctors agree that losing weight, cutting back on intake of salt and fats, and quitting smoking are important precautions.
A recent study initiated by the National Heart, Lung & Blood Institute showed that healthy subjects with blood pressure in the high-normal range could achieve a noticeable decrease in diastolic blood pressure just by slimming down. People who weigh 30% more than they ideally should are especially at risk. The heart is burdened by carrying extra pounds, and obesity raises the levels of cholesterol in the blood.
Diet can affect weight and other hypertension risk factors by lowering the intake of cholesterol and saturated fats. Cholesterol is a fatty substance the body uses to build cell membranes and make hormones. While the liver makes enough of it, Americans ingest about half again that amount in cholesterol and saturated fats found mostly in animal-based foods. Excess cholesterol can gather on artery walls and build up plaque. The "good" cholesterol--high-density lipoproteins (HDLs)--mops up loose "bad" cholesterol and recycles or eliminates it. But obesity, smoking, and the male hormone progesterone, for example, can depress HDL levels. Indeed, estrogen, which raises HDL and lowers LDL, protects premenopausal women from cardiovascular ailments.
SMOKE SIGNAL. Salt was long thought to be a cause of hypertension because the sodium in it retains water, adding to the liquid volume of blood and hence the heart's workload. But recent studies show that salt makes a dramatic difference only in certain "salt-sensitive" people. Other nutrients such as calcium, potassium, and magnesium may help lower blood pressure, but there's no definitive proof.
Even though smoking doesn't cause high blood pressure per se, it is a contributing factor: For starters, it holds fats and cholesterol in the blood longer, according to a recent study at the Veterans Administration Medical Center in San Francisco. Smoking also damages artery walls and causes platelets in the blood to become sticky and cluster on walls or in clots. Alcohol, too, in large amounts seems to worsen high blood pressure, especially in older men.
Although stress has been linked to hypertension, there is little evidence that relaxation techniques and stress management alleviate it. And many researchers say stress is just too hard to quantify to know for sure.
Treatment of high blood pressure is starting to change. Doctors are moving away from strict lifelong drug intervention and "stepped care," which means if one drug doesn't work, another is added to the brew. "Doctors are starting to resist putting people on drugs," says Dr. John Laragh, director of the Hypertension & Cardiovascular Center at New York Hospital-Cornell Medical Center. "As wonderful as these drugs are, there's no drug as good as no drug."
Doctors at his clinic keep patients off drugs as long as possible and try to wean them from medication once their blood pressure stabilizes at an acceptable level. "The traditional party line is: You keep them on drugs forever," he says. "Our goal is to reduce the amount of drugs and then finally get rid of them."
But where nondrug methods fail, doctors can choose from at least five different kinds of drugs that lower blood pressure. All have side effects, ranging from dizziness and depression to impotence. But not everyone suffers from them. Diuretics lower pressure by ridding the body of excess water through urination. Beta blockers impede the action of the hormone epinephrine, which causes the heart to beat faster. Both drugs can raise cholesterol.
Recent treatments such as calcium-channel blockers keep calcium from entering arterial muscle cells: Calcium can cause them to contract. Blood-vessel dilators act directly on the muscles in the arteries to relax them. Angiotensin-converting enzyme inhibitors block the production of an artery-constricting hormone called angiotensin II. These drugs don't raise cholesterol, but they have side effects such as insomnia, coughing, and constipation, and they have not been tested for long-term effectiveness. More specific drugs are in the pipeline.
Doctors are still a long way from solving the riddle of hypertension. But "the way things are moving, we'll have some of these answers in my lifetime," says the AHA's Cowley. "And I'm not exactly a youngster."HELPING KEEP THE PRESSURE DOWN
-- Try to limit your consumption of salt. Watch out for sodium in canned and
processed foods. Use spices such as garlic, curry, tarragon, and lemon juice to
replace salt for flavor
-- Consume foods rich in calcium (broccoli, lowfat yogurt, skim milk),
potassium (fresh fruits, vegetables, fish), and magnesium (soy flour,
tofu, unblanched almonds, wheat germ)
-- Limit cholesterol intake to 300 milligrams a day. Eat less meat, eggs,
and dairy products, which are high in saturated fats and cholesterol.
Eat more lean meat, fish, poultry, and fresh fruits and vegetables.
Try to limit your caloric intake of fat to 30% of your total daily calories.
And limit your consumption of saturated fats to only 10% of that
-- Try to stay at least within 15% of the ideal weight for your height,
gender, and build
-- Exercise aerobically--at least 15 to 30 minutes every other day.
Avoid isometric exercise
-- Don't smoke, and limit alcohol intake to two ounces a day of liquor,
8 ounces of wine, or 24 ounces of beer
DATA: AMERICAN HEART ASSN.; PEOPLE'S MEDICAL SOCIETY
Pam Black EDITED BY AMY DUNKIN