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“The Pressure’s On” – America ’s No.1 Killer |
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Cardiovascular Disease |
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It's America's No. 1 killer, responsible for almost a million deaths a year—twice as many as cancer. In fact, it leads to more deaths than the next five causes combined. It's cardiovascular disease, and a leading cause of death among African Americans. Here's what we've learned about prevention, treatment and the ways heart disease may differ depending on who you are. |
by Marianne Legato, M.D. |
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| To many people, the word hypertension suggests excessive tension, nervousness, or stress. In medical terms, hypertension refers to high blood pressure, regardless of the cause. Because it usually does not cause symptoms for many years—until a vital organ is damaged—it has been called "the silent killer." Uncontrolled high blood pressure increases the risk of problems such as stroke, aneurysm, heart failure, heart attack, and kidney damage. | |
| When blood pressure is checked, two values are recorded. The higher value reflects the highest pressure in the arteries, which is reached when the heart contracts (during systole). The lower value reflects the lowest pressure in the arteries, which is reached just before the heart begins to contract again (during diastole). Blood pressure is written as systolic pressure/diastolic pressure—for example, 120/80 mm Hg (millimeters of mercury). This reading is referred to as "120 over 80." | |
| High blood pressure is defined as a systolic pressure at rest that averages 140 mm Hg or more, a diastolic pressure at rest that averages 90 mm Hg or more, or both. However, the higher the blood pressure, the greater the risks—even within the normal blood pressure range—so these limits are somewhat arbitrary. | |
| The Body's Control of Blood Pressure | |
| The body has many mechanisms that control blood pressure: The body can change the amount of blood the heart pumps, the diameter of arteries, and the volume of blood in the bloodstream. To increase blood pressure, the heart can pump more blood by pumping more forcefully or more rapidly. Small arteries (arterioles) can narrow (constrict), forcing the blood from each heartbeat through a narrower space than normal. Because the space in the arteries is narrower, the same amount of blood passing through them increases the blood pressure. Veins can constrict to reduce their capacity to hold blood, forcing more blood into the arteries. As a result, blood pressure increases. Fluid can be added to the bloodstream to increase blood volume and thus increase blood pressure. Conversely, to decrease blood pressure, the heart can pump less forcefully or rapidly, arterioles and veins can widen (dilate), and fluid can be removed from the bloodstream. | |
| If blood pressure increases, the kidneys increase their excretion of salt and water, so that blood volume decreases and blood pressure returns to normal. Conversely, if blood pressure decreases, the kidneys decrease their excretion of salt and water, so that blood volume increases and blood pressure returns to normal. The kidneys can increase blood pressure by secreting the enzyme renin, which eventually results in the production of the hormone angiotensin II. Angiotensin II helps increase blood pressure by causing the arterioles to constrict and by triggering the release of another hormone, aldosterone, which causes the kidneys to increase the retention of salt and water. | |
| Causes of Hypertension | |
| Several changes in the heart and blood vessels probably combine to increase blood pressure. For instance, the amount of blood pumped per minute (cardiac output) may be increased, and the resistance to blood flow may be increased because blood vessels are constricted. Blood volume may be increased also. The reasons for such changes are not fully understood but appear to involve an inherited abnormality affecting the constriction of arterioles, which help control blood pressure. | |
| Many kidney disorders can cause high blood pressure, because the kidneys are important in controlling blood pressure. For example, damage to the kidneys may impair their ability to remove enough salt and water from the body, increasing blood volume and blood pressure. | |
| A hormonal disorder or use of certain drugs, such as birth control pills (oral contraceptives) can cause high blood pressure. Arteriosclerosis interferes with the body's control of blood pressure, increasing the risk of high blood pressure. Arteriosclerosis makes arteries stiff, preventing the dilation that would otherwise return blood pressure to normal. | |
| Obesity, a sedentary lifestyle, stress, smoking, and excessive amounts of alcohol or salt in the diet all can play a role in the development of high blood pressure in people who have an inherited tendency to develop it. Stress tends to cause blood pressure to increase temporarily, but blood pressure usually returns to normal once the stress is over. An example is "white coat hypertension," in which the stress of visiting a doctor's office causes blood pressure to increase enough to be diagnosed as high blood pressure in someone who has normal blood pressure at other times. | |
| Symptoms | |
| In most people, high blood pressure causes no symptoms, despite the coincidental occurrence of certain symptoms that are widely, but erroneously, associated with high blood pressure: headaches, nosebleeds, dizziness, a flushed face, and fatigue. People with high blood pressure may have these symptoms, but the symptoms occur just as frequently in people with normal blood pressure. | |
| Severe or long-standing high blood pressure that is untreated can produce symptoms because it can damage the brain, eyes, heart, and kidneys. Symptoms include headache, fatigue, nausea, vomiting, shortness of breath, restlessness, and blurred vision. Occasionally, severe high blood pressure causes the brain to swell, resulting in nausea, vomiting, worsening headache, drowsiness, confusion, seizures, sleepiness, and even coma. | |
| When pressure in the arteries is increased above 140/90 mm Hg, the heart enlarges and the heart's walls thicken because the heart has to work harder to pump blood. The thickened walls are stiffer than they normally are. Consequently, the heart's chambers do not expand normally and are harder to fill with blood, further increasing the heart's workload. These changes in the heart may result in abnormal heart rhythms and heart failure. | |
| Diagnosis | |
| Blood pressure is measured after a person sits or lies down for 5 minutes. It should be measured again after the person stands for a few minutes, especially if the person is older or has diabetes. A reading of 140/90 mm Hg or more is considered high, but a diagnosis cannot be based on a single high reading. If a person has an initial high reading, blood pressure is measured again during the same visit and then measured twice on at least two other days to make sure that the high blood pressure persists. | |
| If there is still doubt, a 24-hour blood pressure monitor may be used. It is a portable battery-operated device, worn on the hip, connected to a blood pressure cuff, worn on the arm. This monitor repeatedly records blood pressure throughout the day and night over a 24-hour or 48-hour period. | |
| After high blood pressure has been diagnosed, its effects on key organs, especially the blood vessels, heart, brain, and kidneys, are usually evaluated. Doctors also look for the cause of high blood pressure. The number and type of tests that are performed to look for organ damage and to determine the cause of high blood pressure vary from person to person. In general, routine evaluation for all people with high blood pressure involves a medical history, a physical examination, electrocardiography (ECG), blood tests (including a complete blood cell count), and urine tests. The higher the blood pressure and the younger the person, the more extensive the search for a cause is likely to be, even though a cause is identified in less than 10 percent of people. | |
| Treatment | |
| Primary hypertension cannot be cured, but it can be controlled to prevent complications. Because high blood pressure itself has no symptoms, doctors try to avoid treatments that cause side effects or interfere with a person's lifestyle. Before any drugs are prescribed, alternative measures are usually tried. | |
| Overweight people with high blood pressure are advised to lose weight. Losing as few as 10 pounds can lower blood pressure. For people who are obese or who have diabetes or high cholesterol levels, changes in diet are important for reducing the risk of heart and blood vessel disease. Smokers should stop smoking. | |
| Reducing the intake of alcohol and sodium (while maintaining an adequate intake of calcium, magnesium, and potassium) may make drug therapy for high blood pressure unnecessary. Daily alcohol intake should be reduced to no more than 2 drinks (a daily total of 24 ounces of beer, 8 ounces of wine, or 2 ounces of 100-proof whiskey or other liquor). Daily sodium intake should be reduced to less than 2 grams, or sodium chloride intake to 5 grams. | |
| Moderate aerobic exercise is helpful. People with primary hypertension do not have to restrict their physical activity as long as their blood pressure is controlled. Regular exercise helps reduce blood pressure and weight and improves the functioning of the heart and overall health. | |
| Doctors often recommend that people with high blood pressure monitor their blood pressure at home. Monitoring their own blood pressure probably helps motivate people to follow a doctor's recommendations regarding treatment. | |
| Drug Therapy | |
| Drugs that are used in the treatment of high blood pressure are called anti-hypertensives. With the wide variety of anti-hypertensives available, high blood pressure can be controlled in almost everyone, but treatment has to be tailored to the individual. | |
| Different types of anti-hypertensives reduce blood pressure by different mechanisms; therefore, many different treatment strategies are possible. For some people, doctors use a stepped approach to drug therapy: They start with one type of anti-hypertensive and add others as necessary. For other people, doctors find a sequential approach is preferable: They prescribe one anti-hypertensive; if it is ineffective, they discontinue it and prescribe another type. In choosing an anti-hypertensive, doctors consider such factors as the person's age, sex, and race; the severity of high blood pressure; the presence of other conditions, such as diabetes or high blood cholesterol levels; potential side effects, which vary from drug to drug; and the costs of the drugs and of tests needed to check for certain side effects. | |
| Most people tolerate their prescribed anti-hypertensive drugs without problems. But any drug can cause side effects. If side effects develop, a person should tell the doctor, who can adjust the dose or substitute another drug. Usually, an anti-hypertensive drug must be taken indefinitely to control blood pressure. | |
| Dr. Legato is an emeritus professor of clinical medicine at Columbia University in New York City and the founder and director of the Partnership for Gender-Specific Medicine. To learn more about high blood pressure and other health topics, visit www.YourHealthNow.com. | |
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Web Site of the City of St. Louis This Page Last Modified: Monday, 19-Nov-2007 16:43:32 CST |
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