High blood pressure


From time to time, we're, conscious of our bodies inner workings. We may detect a heart beat, a digestive rumble, or a uterine contraction, but we aren't aware of our blood pressure. It is mute, and even when it becomes dangerously high, raising the risk of stroke, heart attack, kidney damage, and vision loss, there may be no symptoms. It is known as a silent killer, but, with proper treatment, one that is easily arrested.

Blood pressure is the force exerted against the walls of the arteries and arterioles, vessels that carry blood from the heart. When these muscular walls constrict, reducing the diameter of the vessel, blood pressure rises; when they relax, increasing the vessel diameter, it falls. Blood pressure usually rises in response to exercise and stress; it falls when we're at rest. It also mounts when blood volume -the amount of fluid in the vessels -- increases.

A blood pressure measurement is a "snapshot" of one's blood pressure at a given moment. The person who takes your pressure will wrap a cuff around your upper arm and inflate it until it compresses an artery, stopping blood flow. He or she will then slowly release the air from the cuff while listening to the artery through a stethoscope. The clinician will hear the blood flow into the vessel when the pressure in the cuff equals that in the artery. The reading at that point represents the systolic pressure, or the pressure when the heart muscle is contracting. The reading taken when sounds are no longer heard represents the diastolic pressure, or the pressure when the heart muscle is relaxed. The systolic pressure is the top number, and the diastolic pressure is the bottom number of the reading.

A normal blood pressure reading is an indication that the arteries and heart are dilating and contracting properly to deliver blood to all parts of the body. Your clinician might want to take several readings -while you are standing, sitting, and lying down -- to see how your blood pressure responds to change. If your doctor suspects that the office reading is higher than it might normally be due to the stress of the office visit -- a phenomenon called "white coat hypertension" -- he or she may recommend a 24-hour reading taken with a home monitor.

A high blood pressure reading is usually a sign that the vessels cannot relax fully. They remain somewhat constricted, requiring the heart to work harder to pump blood through them. Over time, the extra effort can cause the heart muscle to become enlarged and eventually weakened. The force of blood pumped at high pressure can also produce small tears in the lining of the arteries, weakening the arterial vessels. The evidence of this is most pronounced in the vessels of the brain, those to the kidneys, and the small vessels of the eye.

Treating high blood pressure
Hypertension is defined by an elevation of diastolic pressure, systolic pressure, or both. A diastolic pressure below 85 is considered normal; 85-89, high normal; 90-104, mild hypertension; 105-114, moderate hypertension, and greater than 115, severe hypertension. Systolic pressures of 140-159 are defined as borderline systolic hypertension and those over 160 as systolic hypertension. A diastolic pressure over 90 and/or a systolic pressure over 160 has been consistently linked with an increased risk of stroke, heart failure, coronary artery disease, kidney damage, and vision loss.

The risk of hypertension increases with age as arteries lose elasticity and become less able to relax. About 70% of women between the ages of 65 and 75 have high blood pressure, particularly high systolic pressure.

African-American women are at even higher risk than Caucasians. Those who develop high blood pressure do so earlier in life and have more severe elevations. They also experience a greater increase in the risk of stroke or heart disease as a result. By age 65 almost 80% of black women have high blood pressure.

As a rule, the treatment depends on how high blood pressure is and whether symptoms of heart disease, kidney damage, or vision loss are present. The following are recommendations for each level of hypertension:

• High normal. Try to reduce the known risk factors for high blood pressure. Diet and exercise are key.

There is mounting evidence that the minerals calcium, potassium, and magnesium are protective, especially when obtained through a diet rich in low-fat dairy products, green leafy vegetables, fruits, and grains. Restrict sodium to 2,400 mg a day. (Although recent studies indicate that only a fraction of people with elevated blood pressure are sodium sensitive, the only way to determine if you are is to minimize salt consumption and see if your blood pressure falls.) Increase dietary fiber to 25 grams daily and limit alcohol consumption to one drink a day.

Exercise can also be beneficial. Try to get at least 30 minutes of moderate exercise every day. Other techniques, such as relaxation and biofeedback, though appealing in theory, haven't reduced blood pressure significantly in clinical trials.

Following the proper diet and exercise routine should also help to keep weight down. Women who are more than 10% above ideal weight can often lower their blood pressure by losing the extra pounds.

If you're past menopause, hormone replacement therapy shouldn't increase your blood pressure. Although the results are inconclusive, estrogen, which is thought to relax blood vessels, has been associated with reductions in blood pressure in some studies.

Mild hypertension and borderline systolic hypertension. Because drug treatment may lead to a lifetime on medication, which in itself may have some complications, most experts believe that the dietary and life-style changes recommended for people with high normal blood pressure should be the first approach. If these fail to lower blood pressure, drug treatment is recommended.
Moderate and severe hypertension. This includes isolated systolic hypertension (systolic hypertension with normal diastolic pressure), which is common in older women. Drug treatment is recommended.
Drug therapy
The following classes of drugs are commonly used for high blood pressure:

Diuretics, also known as "water pills," which lower pressure by eliminating sodium and water and thus reduce the volume of blood in circulation, are often the first approach. They may be beneficial for women who have benign bloating or swelling and are particularly effective in African-American women. Thiazide diuretics, which increase calcium reabsorption by the kidneys, can also help to prevent osteoporosis. Some diuretics remove potassium from the body, so those who use them may need to eat more potassium-rich foods or take a supplement.
Beta blockers relax not only the blood vessels, but the heart muscle, producing a decline in the force of contraction and a reduction in heart rate. These drugs may be a good choice for women who are anxious but aren't recommended for those who like to exercise vigorously or for people with asthma. They may not be as effective for black women as for whites.
Angiotensin-converting enzyme (ACE) inhibitors are highly selective drugs that interrupt a chain of molecular messengers that constrict blood vessels. They can improve cardiac function in people with heart failure and are good choices for those with diabetes or early kidney damage. Rashes and coughs are common side effects.
Calcium channel blockers inhibit calcium from entering the blood vessel walls where it powers the process that constricts blood vessels. Because recent studies have indicated that short acting calcium blockers increase heart-attack risk in some people, they should be used cautiously.
In the past, drug therapy began with diuretics. If those drugs didn't bring pressure down, others were added to the regimen. Today, there are so many different agents available that a single drug treatment is likely to be adequate for most women. When the original drug isn't effective, another is usually substituted.

Diuretics and beta-blockers are the only drugs that have been extensively studied and shown to reduce the risk of heart disease, stroke, and death in clinical trials. However, many others effectively reduce blood pressure and are likely to have comparable benefits.

Secondary hypertension
In about 5% of cases, high blood pressure fails to respond to medication. In these instances, it may be due to a specific medical problem, such as an adrenal tumor or kidney disease. It will usually resolve if the underlying condition is successfully treated.

Oral contraceptive use may cause blood pressure to rise in some women, although today's birth control pills, which contain lower doses of estrogen and/or progestin, are less likely to have this effect than earlier formulations. High blood pressure due to the pill usually returns to normal when women stop taking it.

Preeclampsia, also called pregnancy-induced hypertension, affects many systems in the body. Its cause is unknown. Frequent prenatal checkups to monitor blood pressure and protein in the urine -signs of preeclampsia -- are important. Although hospitalization or bed rest is often the treatment of choice, antihypertensives are occasionally prescribed. Blood pressure usually returns to normal following delivery.

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