Finding right treatment for high blood pressure is tricky

Medical Matters

Medicine & Science

March 17, 2003|By Judy Foreman | Judy Foreman,SPECIAL TO THE SUN

In December, a study of more than 42,000 white and black Americans found that old-fashioned diuretics - "water pills" - work at least as well and sometimes better than more expensive drugs to treat high blood pressure.

The study was published in the Journal of the American Medical Association. In February, a study of more than 6,000 mostly white Australians came to a different conclusion - that drugs called ACE inhibitors were better than diuretics, although only for men. This study was published in the New England Journal of Medicine.

Between now and May, it falls to Dr. Aram Chobanian, dean of the Boston University School of Medicine, and other experts picked by the National Heart Lung and Blood Institute to reconcile the studies and tell America's 50 million hypertensives what to do.

Their conclusions are crucial. Hypertension doubles the risk of heart attack and is the leading risk factor for stroke and heart failure. One in four adult Americans has hypertension - defined as a blood pressure reading of 140/90 or higher.

High blood pressure is so common, especially among older people, that many patients don't take it as seriously as they should.

High blood pressure is also tricky for doctors because they usually don't know what causes it. In 5 percent of cases, it is caused by kidney and adrenal problems, or by substances such as prednisone, cocaine, ephedrine, even licorice. But in most cases, the cause is unknown.

Basically, blood pressure is a matter of hydraulics. If the pressure inside artery walls is too low, a person can go into shock and die. If the pressure is too high, because vessels are too narrow or rigid or the heart beats too hard, a person can develop heart and kidney failure and stroke.

Regulation of blood pressure is complex. Short-term fluctuations are controlled by the nervous system, specifically hormones such as adrenalin and noradrenalin. Longer term, a key player is angiotensin II, a kidney hormone that makes vessels constrict.

The first remedy for hypertension is exercise and nutrition. That means losing weight if you're heavy, restricting salt and adopting a diet rich in fruits, vegetables, lowfat dairy foods, potassium, calcium, magnesium, fiber and protein.

Stress reduction helps, too. Dr. Thomas Graboys, chairman of the Lown Cardiovascular Foundation, asks patients two questions: Do you look forward to going to work? And, do you look forward to going home at night? "If someone says no to either," he says, stress may be contributing to the hypertension.

If diet, exercise and stress reduction fail, then medication may be needed. If hypertension is stubborn, several drugs may be required.

Diuretics such as hydrochlorothiazide (Hydrodiuril) or chlorthalidone (Hygroton) flush excess water and salt from the body, allowing the heart to work less hard. One reason diuretics fared well in the JAMA study is that 32 percent of participants were black. Blacks, perhaps for genetic reasons, tend to be sensitive to salt and hence, highly responsive to diuretics.

Beta-blockers such as propanolol (Inderal) are another staple. They reduce nerve impulses to the heart and blood vessels, making the heart beat more slowly and with less force. Acting similarly are the alpha blockers such as doxazosin (Cardura). ACE-inhibitors such as lisinopril (Zestril) relax blood vessels by blocking the formation of angiotensin II. (A newer class of drugs called angiotensin antagonists such as losartan [Lotrel] act differently, by blocking receptors for angiotensin II in vessels.) And then there are the calcium channel blockers, drugs such as amlodipine (Lotrel). They lower pressure by blocking calcium, which causes vessels to constrict.

Granted, it is a bit confusing. But it's "very reassuring" that the JAMA study found diuretics to be so effective, says Dr. Sid Smith, past president of the American Heart Association and professor of medicine at the University of North Carolina, Chapel Hill.

There's an added benefit: Diuretics are cheap - about 13 cents a pill vs. 10 times that for other medications.

Judy Foreman is a lecturer on medicine at Harvard Medical School and an affiliated scholar at the Women's Studies Research Center at Brandeis University. Her column appears every other week. Past columns are available at www.myhealthsense.com.

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