Week 13

Dietary Approaches for Blood Pressure Reduction

A number of research studies have shown that a significant reduction in blood pressure can be achieved by following a diet that emphasizes fruit, vegetables, and whole grains and includes low-fat milk products, poultry, fish, and nuts.71 This type of dietary pattern provides more fiber, potassium, magnesium, and calcium than the typical American diet. The most popular diet tested in these studies, known as the DASH Eating Plan (see Table 21-5), also limits red meat, sweets, sugar-containing beverages, saturated fat (to 7 percent of kcalories), and cholesterol (to 150 milligrams per day), so it is beneficial for reducing CHD risk as well.72 During the eight-week study period when hypertensive subjects consumed the DASH diet, their systolic blood pressures fell by 11.4 mm Hg more than the blood pressures of subjects who remained on the standard American control diet.73 The DASH Eating Plan is even more effective when accompanied by a low sodium intake. In a research study that tested the blood pressure-lowering effects of the DASH dietary pattern in combination with sodium restriction, the best results were achieved when sodium was reduced to 1500 milligrams daily—a level much lower than the amounts typically consumed in the United States (average sodium intakes for men and women are about 4100 milligrams and 3000 milligrams per day, respectively74). Note that a sodium intake as low as 1500 mg per day may lead to health problems in some individuals;* thus, the optimal sodium intake for hypertensive patients is still in question. Sodium restriction by itself can have a modest blood pressure-lowering effect (review Table 21-4), but some people are more responsive than others. Although a low-sodium diet may improve blood pressure to some extent, it should be combined with other lifestyle modifications for greater effect. Box 21-11 lists practical suggestions for restricting sodium intake; additional detail is provided in Table 22-1 on p. 629.

Managing Lifestyle Changes

Adopting multiple lifestyle changes at once is challenging. Health practitioners can help to motivate patients by explaining the reasons for each change, setting obtainable goals, and providing practical suggestions. In some individuals, high LDL levels may persist despite adjustments in health behaviors, and drug therapy may be the only effective treatment. Review Table 21-3 for a summary of the recommendations discussed in this section. Box 21-4 offers suggestions for implementing a heart-healthy diet.

21.4 Hypertension

Although people cannot feel the physical effects of hypertension (high blood pressure), it is a primary risk factor for atherosclerosis and cardiovascular diseases. In addition to hypertension's damaging effect on arteries, elevated blood pressure forces the heart to work harder to eject blood into the arteries; this effort weakens heart muscle and increases the risk of developing heart arrhythmias, heart failure, and even sudden death. Hypertension is also a primary cause of stroke and kidney failure, and reducing blood pressure can dramatically reduce the incidence of these diseases. Photo 21-3 shows a common technique for measuring blood pressure, and Box 21-9 explains how to interpret blood pressure readings. Hypertension affects about 46 percent of adults in the United States.55 Prevalence is especially high in African Americans, who develop hypertension earlier in life and sustain higher average blood pressures throughout their lives than other ethnic groups. An estimated 16 percent of people with hypertension are unaware that they have it.

Age and Sex

As a person ages, arterial cells tend to degenerate, and risk factors for CVD accumulate. The risk of atherosclerosis increases significantly in men and women older than 45 and 55 years of age, respectively. After menopause, women's risk increases, in part, because the decline in estrogen has unfavorable effects on lipoprotein levels and arterial function.*12 Elevated levels of the amino acid homocysteine, which may impair endothelial cell function, have been associated with aging and are more prevalent in men; however, it is unclear whether the increased homocysteine levels directly contribute to the disease process or are merely an indicator of abnormal metabolism.

Consequences of Atherosclerosis

As atherosclerosis worsens, it may eventually narrow the lumen of an artery and interfere with blood flow. Some types of plaque are highly susceptible to rupture, which promotes blood clotting within the artery (thrombosis). A blood clot (thrombus) may enlarge in time and ultimately obstruct blood flow. A portion of a clot can also break free (embolus) and travel through the circulatory system until it lodges in a narrowed artery and shuts off blood flow to the surrounding tissue (embolism). Most complications of atherosclerosis result from the deficiency of blood and oxygen within the tissue served by an obstructed artery (ischemia). Atherosclerosis can affect almost any organ or tissue in the body and, accordingly, is a major cause of disability or death. Obstructed blood flow in the coronary arteries can cause pain or discomfort in the chest and surrounding regions (angina pectoris) or lead to a heart attack. As mentioned earlier, obstructed blood flow to the brain can injure or destroy brain tissue, causing a stroke. Impaired blood flow in the arteries of the legs (peripheral artery disease) can cause pain and weakness in the legs and feet, especially while walking. Blockage of the arteries that supply the kidneys can result in kidney disease or even kidney failure. Atherosclerosis is the most common cause of an aneurysm—the abnormal dilation of a blood vessel. Plaque can weaken the blood vessel wall, and eventually the pressure of blood flow can cause the damaged region to stretch and balloon outward. Aneurysms can rupture and lead to massive bleeding and death, particularly when a large vessel such as the aorta is affected. In the arteries of the brain, an aneurysm may lead to bleeding within the brain, coma, or a stroke.

Polyunsaturated and Monounsaturated Fat

As described in the previous section, replacing saturated fat with either monounsaturated or polyunsaturated fat helps to lower LDL levels; a switch to polyunsaturated fat tends to have the greater effect. In addition, replacing saturated fat with polyunsaturated fat has been associated with reductions in morbidity and mortality from CHD.25 Note that most polyunsaturated fat in the diet consists of omega-6 fatty acids such as linoleic acid; omega-3 fatty acids may also have beneficial effects on heart disease risk, as described in a later section.

Treatment of Heart Attack

As explained earlier, a heart attack occurs when the blood supply to heart muscle is blocked, causing death of heart tissue (see Photo 21-2 and Box 21-7). The damage to heart muscle may result in cardiac arrhythmias or even heart failure. Drug therapies given immediately after a heart attack may include thrombolytic drugs (sometimes called clot-busting drugs), aspirin, anticoagulants, painkillers, and medications that regulate heart rhythm and reduce blood pressure. Patients are not given food or beverages, except for sips of water or clear liquids, until their condition stabilizes.50 Once able to eat, they are offered a heart-healthy diet, limited to 2000 milligrams of sodium per day, in small portions or as tolerated. The sodium restriction helps to limit fluid retention but may be lifted after several days if the patient shows no signs of heart failure. A heart attack patient needs to regain strength and learn strategies that can reduce the risk of a future heart attack; such strategies are similar to the lifestyle changes described earlier. Thus, the cardiac rehabilitation programs in hospitals and outpatient clinics include exercise therapy, instruction about heart-healthy food choices, help with smoking cessation, and medication counseling. These programs often last several months. Home-based rehabilitation programs are also beneficial but they are more limited in scope and lack the benefit of group interaction.

B Vitamin Supplements and Homocysteine

As mentioned earlier, elevated blood homocysteine is a risk factor for atherosclerosis, but the exact role of homocysteine in the disease process remains unknown. Although increased intakes of folate, vitamin B6 , and vitamin B12 can lower homocysteine levels, clinical trials have not demonstrated that supplementation with these vitamins can reduce the incidence of heart attacks in those at risk.41 Hence, B vitamin supplements are not currently recommended for patients at risk for CHD.

Total Fat

As mentioned previously, limiting the total fat intake may indirectly reduce saturated fat; the general recommendation is a fat intake of about 25 to 35 percent of the energy intake.26 Individuals with elevated blood triglycerides may benefit from achieving a fat intake at the upper end of this range (30 to 35 percent) so that their carbohydrate intakes are not excessive. Fat intakes higher than 35 percent of kcalories are discouraged because they may promote weight gain in some people.

Factors That Influence Blood Pressure

As shown in Figure 21-3, blood pressure depends on the volume of blood pumped by the heart (cardiac output) and the resistance the blood encounters in the arterioles (peripheral resistance). When either cardiac output or peripheral resistance increases, blood pressure rises. Cardiac output is raised when heart rate or blood volume increases; peripheral resistance is affected mainly by the diameters of the arterioles and blood viscosity. Blood pressure is therefore influenced by the nervous system, which regulates heart muscle contractions and arteriole diameters, and hormonal signals, which may cause fluid retention or blood vessel constriction. The kidneys also play a role in regulating blood pressure by controlling the secretion of the hormones involved in vasoconstriction and retention of sodium and water.

Evaluating Risk for Coronary Heart Disease

Because heart disease develops over many years, prevention should begin well before symptoms appear. The American Heart Association (AHA) and American College of Cardiology (ACC) recommend a review of CHD risk factors every four to six years in individuals who are 20 to 79 years of age.15 The major risk factors for CHD are listed in Table 21-1; most of those listed can be modified by changes in diet and lifestyle. The AHA and ACC have developed an online calculator to predict 10-year and lifetime atherosclerotic CVD risk that includes some of these variables (available at tools.acc .org/ASCVD-Risk-Estimator-Plus/#!/calculate/estimate/).

Antioxidant Supplements

Because oxidative stress promotes atherosclerosis, researchers have hypothesized that antioxidant supplementation may inhibit atherosclerosis For many people, following a heart-healthy diet may require significant changes in food choices. It is often easier to adopt a new diet if only a few changes are made at a time. Discussing positive choices (what to eat) first, rather than negative ones (what not to eat), may improve compliance. These suggestions can help patients implement their diet: Breads, Cereals, and Pasta ● Choose whole-grain breads and cereals. Make sure the first ingredient on bread and cereal labels is "whole wheat flour" rather than "enriched wheat flour." Consume oats and barley regularly, as they are good sources of soluble fiber. ● Bakery products and snack foods often contain trans fat. Buy only food products that list 0 grams of trans fat on the Nutrition Facts panel. Ingredient lists should not include any "partially hydrogenated vegetable oil," the main source of trans-fatty acids. Fruits and Vegetables ● Incorporate at least one or two servings of fruits and vegetables into each meal. Keep the refrigerator stocked with a variety of ready-to-eat fruits and vegetables (baby carrots, blueberries, grapes) for snacks. ● Check food labels on canned products carefully. Canned vegetables (especially tomato-based products) are often high in sodium. Fruit that is canned in juice is higher in nutrient density than that canned in syrup. ● Avoid french fries from fast-food restaurants, which are often prepared with trans fat. Restrict high-sodium foods such as pickles, olives, sauerkraut, and kimchee. Lunch and Dinner Entrées ● Prepare plant-based entrees whenever possible. Use soybean products and other legumes as sources of protein in soups, stews, and stir-fry dishes. ● Plan to eat fish twice a week, preferably fatty fish such as salmon, tuna, and mackerel. ● When purchasing meat or poultry, select lean cuts of beef, such as sirloin tip and round steak; lean cuts of pork, such as loin chops and tenderloin; and skinless poultry pieces. Trim visible fat before cooking. ● Select extra-lean ground meat and drain well after cooking. Use lean ground turkey, without skin added, in place of ground beef. ● If you have been advised to reduce cholesterol intake, limit cholesterol-rich organ meats (liver, brain, sweetbreads) and shrimp. Replace whole eggs in recipes with egg whites or commercial egg substitutes. ● Restrict these high-sodium foods: cured or smoked meat such as beef jerky, bologna, corned beef, frankfurters, ham, luncheon meat, salt pork, and sausage; salty or smoked fish such as anchovies, caviar, salted or dried cod, herring, and smoked salmon; and canned, frozen, or packaged soups, sauces, and entrées. Milk Products ● Select fat-free or low-fat milk products only. Use yogurt or fat-free sour cream to make dips or salad dressings. Substitute fat-free evaporated milk for heavy cream. ● Limit foods high in saturated fat or sodium, such as butter, sour cream, processed cheese, and ice cream or other milk-based desserts. Fats and Oils ● Prepare salad dressings and other foods with vegetable oils rich in omega-3 fatty acids, such as canola, soybean, flaxseed, and walnut oil. Select other unsaturated vegetable oils—such as corn, olive, peanut, sesame, safflower, and sunflower oil—instead of saturated fat sources such as butter and lard. ● Select only margarine products that list 0 grams of trans fat on the Nutrition Facts panel, and avoid products that list "partially hydrogenated vegetable oil" as an ingredient. To help lower LDL cholesterol levels, use margarines with added plant sterols or stanols. ● Add unsalted nuts, seeds, or avocados to meals to make them more appetizing; these foods are good sources of unsaturated fat. Spices and Seasonings ● Use salt only at the end of cooking, and you will need to add much less. Use salt substitutes at the table. ● Check the sodium content on food labels. Flavorings and sauces that are usually high in sodium include bouillon cubes, soy sauce, hoisin sauce, steak and barbecue sauces, relishes, mustard, and catsup. ● Spices and herbs can improve food flavor without adding sodium. Try using more garlic, ginger, basil, curry or chili powder, cumin, pepper, lemon, mint, oregano, rosemary, and thyme. Snacks and Desserts ● Select snacks that are low in sodium and saturated fat, such as unsalted pretzels and nuts, plain popcorn, and unsalted chips and crackers. Avoid products that include trans fat. ● Select low-fat frozen desserts such as sherbet, sorbet, fruit bars, and some low-fat ice creams. ● Snack on canned or dried fruit and crunchy raw vegetables to boost fruit and vegetable intake. Box 21-4 How to Implement a Heart-Healthy Diet 22467_ch21_ptg01.indd 604 9/11/18 5:20 PM Coronary Heart Disease 605 progression and reduce CHD risk. Several epidemiological studies have suggested that antioxidant-rich diets can protect against CHD, but because persons who consume such diets usually maintain a healthy lifestyle and body weight as well, it has been difficult to determine whether the antioxidants were responsible for the effect. Most studies that have tested supplementation with single antioxidants (such as vitamins C or E) or combinations of antioxidants have produced weak or inconsistent results, and several studies suggested possible harm.42 Until more data are available, the use of antioxidant supplements is not recommended for heart disease prevention.

Clinical Measures

CHD risk assessment requires several key laboratory measures, as shown in Table 21-2. A typical lipoprotein profile (also called a blood lipid profile) includes measures of total cholesterol, LDL and HDL cholesterol, and blood triglycerides (VLDL). Some clinicians may use the ratio of total cholesterol to HDL cholesterol or LDL cholesterol to HDL cholesterol to help assess CHD risk. In persons with high blood triglycerides, the non-HDL cholesterol level (total cholesterol value minus the HDL value) may be more accurate than the LDL level for predicting CHD risk.16 Blood pressure and body weight measurements are also regularly included in risk assessment. In some individuals, a CHD risk assessment may include tests that provide additional detail about blood lipids or suggest the presence of atherosclerosis.17 Blood lipid status is sometimes evaluated by measuring LDL and HDL subclasses, the LDL particle number, lipoprotein(a) levels, or levels of proteins or enzymes associated with lipoproteins (especially apolipoprotein B—a component of LDL, lipoprotein(a), and VLDL). Atherosclerosis may be evaluated using the coronary artery calcium score, a value obtained from a computed tomography (CT) scan that analyzes the calcium content of plaque in the coronary arteries. Levels of C-reactive protein, a marker of inflammation, may identify some patients at risk for CHD. The ankle-brachial index, a ratio of blood pressure measurements taken at the ankles and the upper arms, can help to determine the presence or severity of peripheral artery disease.

Diabetes Mellitus

Chronic hyperglycemia leads to the accumulation of advanced glycation end products (AGEs), which promote inflammation and oxidative stress, induce the production of compounds that favor plaque progression, and disturb blood vessel function. By various other mechanisms, diabetes increases tendencies for vasoconstriction, endothelial permeability, plaque rupture, and blood clotting.

Smoking Cessation

Cigarette smoking is a major risk factor for CHD and other types of cardiovascular disease. In addition to promoting atherosclerosis, cigarette smoking decreases the oxygen supplied to heart tissue, raises the heart rate, inhibits vasodilation, promotes blood clotting, and reduces exercise tolerance, among other effects. Smoking just one or two cigarettes daily— even low-tar, low-nicotine cigarettes—increases CHD risk. Quitting smoking improves CHD risk quickly; the incidence of CHD drops to levels near those of nonsmokers within three years.37 Currently, about 17 percent of men and 14 percent of women in the United States are cigarette smokers.38 Although cigar and pipe smoking can also increase the risk of CHD, the risk may not be quite as great because the smoke is less likely to be inhaled.

Cigarette Smoking

Compounds in cigarette smoke (including nicotine) are toxic to endothelial cells and contribute to arterial injury. Other damaging effects of smoking include chronic inflammation, vasoconstriction, enhanced blood coagulation, increased LDL cholesterol, and decreased HDL cholesterol—all effects that can promote the progression of atherosclerosis.

Treatment of Hypertension

Controlling hypertension improves CVD risk considerably: a 10 mm Hg reduction in systolic blood pressure (or a 5 mm Hg reduction in diastolic blood pressure) may lower the risks of death from CHD and stroke by about 45 and 55 percent, respectively.66 Both lifestyle modifications and medications are used to treat hypertension. For many people with stage 1 hypertension (review Box 21-9), changes in diet and lifestyle alone may lower blood pressure to a normal level. Table 21-4 lists lifestyle modifications that can reduce blood pressure and the expected decrease in systolic blood pressure for each change. The recommendations include reducing weight if overweight or obese, adopting a healthy dietary pattern, engaging in regular physical activity, and limiting alcohol intake, if one chooses to drink.67 Combining two or more of these modifications can enhance results. As Table 21-4 shows, weight reduction and dietary adjustments generally have the most significant effects on blood pressure.

21.2 Coronary Heart Disease

Coronary heart disease (CHD), also called coronary artery disease, is the most common type of cardiovascular disease. As discussed earlier, CHD is characterized by impaired blood flow through the coronary arteries, which may lead to angina pectoris, heart attack, or even sudden death. CHD is most often caused by atherosclerosis but occasionally results from a spasm or inflammatory condition that causes narrowing of the coronary arteries.

Nutrition Therapy for Hypertriglyceridemia

Dietary and lifestyle changes can improve most cases of mild hypertriglyceridemia.45 Excessive weight gain and an inactive lifestyle may both raise triglyceride levels. Dietary factors that increase triglyceride levels include high intakes of alcohol and refined carbohydrates; sucrose and fructose are the carbohydrates with the strongest effect. Thus, controlling body weight, being physically active, restricting alcohol, and limiting intakes of refined carbohydrates (especially sweetened beverages and food items made with white flour and added sugars) are basic treatments for hypertriglyceridemia. As mentioned earlier, high triglyceride levels are often associated with low HDL, and the lifestyle changes listed here are likely to improve HDL levels as well.

Blood Pressure Reduction

Excessive dietary sodium may raise blood pressure, whereas potassium can help to lower blood pressure. A lowsodium diet that contains generous amounts of fruits and vegetables, whole grains, nuts, and low-fat milk products has been found to substantially reduce blood pressure, largely due to the diet's content of potassium and several other minerals that have blood pressure-lowering effects. This diet (the DASH Eating Plan) and other lifestyle modifications that may reduce blood pressure are discussed in a later section of this chapter.

Severe Hypertriglyceridemia

Extreme elevations in blood triglycerides are usually caused by genetic mutations that upset lipoprotein metabolism. In addition to dietary and lifestyle changes, medications are usually necessary for lowering blood triglyceride levels above about 500 milligrams per deciliter. If blood triglycerides exceed 1000 milligrams per deciliter, a very low-fat diet, providing 10 to 15 percent of kcalories from fat, may be required.46 Patients must also eliminate consumption of alcoholic beverages.

Fish Oil Supplements and Hypertriglyceridemia

Fish oil supplements are sometimes recommended for treating hypertriglyceridemia. Clinical trials suggest that a daily intake of 4 grams of EPA and DHA (combined) may reduce elevated triglyceride levels by 25 to 30 percent.47 Although fish oil supplements can be effective for reducing blood triglyceride levels, the studies have not shown that their use in hypertriglyceridemia patients can improve cardiovascular disease outcomes.48 In addition, fish oil therapy should be monitored by a physician due to the potential for adverse effects.

Plant Sterols

Foods or supplements that contain significant amounts of plant sterols (or plant stanols) can help to lower LDL cholesterol levels by interfering with cholesterol and bile absorption. These plant compounds are added to various food products, such as margarine and orange juice, or supplied in dietary supplements. About 2 grams of plant sterols daily (provided by 2 to 2½ tablespoons of sterol-enriched margarines) can lower LDL cholesterol by 5 to 10 percent

Nutrition Therapy for Heart Failure

For patients using diuretics, a modest sodium restriction is often advised to help reduce fluid retention. Sodium recommendations typically fall between 1500 and 3000 milligrams per day, depending on the patient's stage of illness, symptoms, and response to diuretic therapy.78 (Note that some research studies have linked sodium intakes lower than 2000 milligrams per day to increased hospital readmissions and mortality rates in heart failure patients, and the ideal sodium intake for this population remains unknown.79) In patients with persistent or recurrent fluid retention, fluid intakes may be restricted to 2 liters per day or less.80 Patients with heart failure may be prone to constipation due to diuretic use and reduced physical activity. Maintaining an adequate fiber intake can help to minimize constipation problems. Because alcohol consumption can worsen heart function, some patients may need to restrict or avoid alcoholic beverages. Individuals who have difficulty eating due to nausea or abdominal bloating may tolerate small, frequent meals better than large meals. No known therapies can reverse cardiac cachexia, and the prognosis is poor. For some patients, liquid supplements, tube feedings, or parenteral nutrition support can be supportive additions to treatment.

Medical Management of Heart Failure

Heart failure is a chronic, progressive illness that may require frequent hospitalizations. Many patients face a combination of debilitating symptoms, complex treatments, and an uncertain outcome. Important goals of medical therapy are to slow disease progression and enhance the patient's quality of life. The specific treatment for heart failure depends on the nature and severity of the illness. Medications help to manage fluid retention and improve heart function. Dietary sodium and fluid restrictions can help to prevent fluid accumulation. Vaccinations for influenza and pneumonia reduce the risk of developing respiratory infections. Treatment of CHD risk factors, such as hypertension and lipid disorders, may slow disease progression. Heart failure patients are encouraged to participate in exercise programs to avoid becoming physically disabled and to improve endurance.

21.5 Heart Failure

Heart failure is characterized by the heart's inability to pump enough blood, resulting in inadequate blood delivery and a buildup of fluids in the veins and tissues. Heart failure has various causes, but it is often a consequence of chronic disorders that create extra work for the heart muscle, such as hypertension or CHD. To accommodate the extra workload, the heart enlarges or pumps faster or harder, but eventually it may weaken enough to fail completely (see Photo 21-4). Heart failure develops mainly in older adults and is the leading cause of hospitalization in individuals over 65 years of age.

Triglycerides may be elevated due to:

High alcohol intake Weight Gain High refined carbohydrate intake A and C All of the above (correct)

Lifestyle Changes for Hypertriglyceridemia

Hypertriglyceridemia (see Box 21-5) affects about 24 percent of adults in the United States.43 It is common in people with diabetes mellitus, obesity, and the metabolic syndrome and may also result from other disorders. Elevated blood triglycerides may coexist with elevated LDL cholesterol or occur separately. Whereas mild or moderate hypertriglyceridemia is often associated with increased CHD risk, more serious cases (blood triglycerides above 500 mg/dL) can cause additional complications, including fatty deposits in the skin and soft tissues and acute pancreatitis.

Factors That Contribute to Hypertension

In 90 to 95 percent of hypertension cases, the cause is unknown (called primary hypertension).57 In other cases, hypertension is caused by a known physical or metabolic disorder (secondary hypertension), such as an abnormality in an organ or hormone involved in blood pressure regulation. For example, conditions characterized by the narrowing of renal arteries often result in the increased production of proteins and hormones that stimulate water retention and vasoconstriction, thereby raising blood pressure. A number of hormonal disorders and medications may also cause secondary hypertension. A number of risk factors for hypertension have been identified, and some can be modified by changes in diet or lifestyle (see Box 21-10). The major risk factors include the following: ● Increased age. Hypertension risk increases with age. In the United States, about 76 percent of persons aged 65 years or older have hypertension.58 Moreover, at least 90 percent of individuals who live long enough are likely to develop hypertension during their lifetimes.59 ● Genetic factors. Risk of hypertension is similar among family members. It is also more prevalent and severe in certain ethnic groups; for example, the prevalence in AfricanAmerican adults is about 58 percent, compared with a prevalence of about 44 percent in whites, 43 percent in Hispanics, and 41 percent in non-Hispanic Asians.60 ● Obesity. Numerous clinical studies have confirmed a strong relationship between excess body fat and increased blood pressure.61 Obesity raises blood pressure, in part, by stimulating the sympathetic nervous system and activating hormonal processes that promote sodium reabsorption and blood vessel constriction.62 ● Salt sensitivity. More than half of the adults in the United States have blood pressure that is sensitive to salt intake.63 Salt sensitivity (also called sodium sensitivity) is influenced by age, sex, genetic factors, body fatness, and the presence of diabetes, kidney disease, or hypertension itself.64 ● Alcohol. Heavy drinking (three or more drinks daily) increases the incidence and severity of hypertension. The mechanisms involved are unclear but probably include activation of the sympathetic nervous system and altered responses of endothelial tissue in the presence of alcohol.65 Alcohol's effects are transient, as blood pressure falls quickly after consumption is stopped. • Dietary factors. A person's diet may influence hypertension risk. As explained later, diets that emphasize vegetables, fruit, and whole grains and include low-fat milk products have been shown to reduce blood pressure.

21.1 Atherosclerosis

In atherosclerosis, the artery walls become progressively thickened due to an accumulation of fatty deposits, fibrous connective tissue, and smooth muscle cells, collectively known as plaque. Atherosclerosis initially arises in response to minimal but chronic injuries that damage the inner arterial wall.3 The first lesions tend to occur in regions where the arteries branch or bend due to the disturbed blood flow in those areas (see Figure 21-2). The subtle damage elicits an inflammatory response, attracting immune cells and increasing the permeability of the artery wall. Low-density lipoproteins (LDL) slip under the artery's thin layer of endothelial cells, become oxidized by local enzymes, and accumulate. Eventually, the plaque thickens and hardens as additional lipids, fibrous proteins, calcium, and cellular debris accumulate. Atherosclerosis begins to develop as early as childhood or adolescence and typically progresses over several decades before symptoms develop

Weight Reduction

In obese individuals, weight reduction may lower blood pressure significantly. Clinical studies suggest that systolic blood pressure can be decreased by about 1 mm Hg for each kilogram of weight loss and that the blood pressure reduction may be sustained for several years.68 In the long term, however (more than three years), blood pressure tends to revert to initial levels, even when weight loss is partially maintained. Weight reduction is most beneficial for blood pressure control during periods when the body weight is actually decreasing.69 Moreover, larger amounts of weight loss seem to provide more substantial improvements in blood pressure than smaller amounts.

Drug Therapies for CHD Prevention

Individuals who cannot improve CHD risk with dietary and lifestyle changes alone may be prescribed one or more medications.49 The drugs most often prescribed for lowering LDL levels are the statins (such as Lipitor and Crestor), which reduce cholesterol synthesis in the liver. Although less effective than the statins, bile acid sequestrants (such as Colestid or Questran) can reduce LDL levels by interfering with bile acid reabsorption in the small intestine. For lowering triglyceride levels and increasing HDL, both fibrates (such as Lopid and Tricor) and nicotinic acid (a form of niacin) are effective; nicotinic acid can also reduce LDL and lipoprotein(a) levels. Individuals using these medications should continue their dietary and lifestyle modifications so that they can use the minimum effective doses of the drugs they require. In addition to lipid-lowering medications, some people may require drugs that suppress blood clotting (such as anticoagulants and aspirin) or reduce blood pressure. Nitroglycerin (a vasodilator) may be given to alleviate angina as needed. Some medications may affect nutrition status or food intake (see Box 21-6); the interactions can be even more complicated when multiple medications are used.

Alcohol

Light to moderate consumption of alcohol—from beer, wine, or liquor—has favorable effects on atherosclerosis, HDL levels, blood-clotting activity, insulin resistance, and overall CHD risk.35 Consumption should be limited to one drink daily for women and two for men, however, because higher intakes may promote plaque formation and increase blood triglyceride levels and blood pressure. Because alcohol consumption increases the risk of various cancers and may have other detrimental effects on health (see Nutrition in Practice 19), nondrinkers are not encouraged to start drinking in an effort to decrease their risk for CHD

Weight Reduction

Obesity—especially abdominal obesity—is often associated with a number of metabolic abnormalities that increase CHD risk, such as insulin resistance, hypertension, elevated blood triglycerides, low HDL levels, and reduced LDL size. In addition, the adipose tissue of obese individuals produces various types of inflammatory mediators and blood clotting factors, raising the risks of both atherosclerosis and heart attack.39 Obesity also strains the heart and blood vessels because cardiac output is greater, resulting in a greater workload for the left ventricle, which pumps blood to the major arteries. In persons who are obese, weight reduction can improve such CHD risk factors as hypertension, blood lipid abnormalities, and insulin resistance. The goal of a typical weight-reduction program is a loss of 5 to 10 percent of a person's initial body weight over the ensuing 6 months, followed by additional periods of weight loss until an acceptable weight is reached.40 For some, maintaining smaller amounts of weight loss may be a desirable starting point.

Saturated Fat

Of the dietary lipids, saturated fat has the strongest effect on blood cholesterol levels, and replacing saturated fats with polyunsaturated or monounsaturated fats can generally lower LDL levels. For individuals with elevated LDL, current guidelines suggest limiting saturated fat intake to less than 7 percent of the total kcalories consumed.21 The response to a reduced saturated fat intake varies among individuals, however, and may depend on the dietary sources of saturated fat, other nutrients in the diet, body fatness, and genetic factors.22 The average saturated fat intake in the United States is about 11 percent of the energy intake.23 For most people, cutting down on saturated fat involves more than just switching from butter to vegetable oil, as the main sources of saturated fat in the United States include cheese, hamburgers, meat and poultry dishes, and various types of desserts. Thus, choosing fat-free or low-fat milk products,* selecting lean meat or fish, and avoiding certain types of desserts are usually more effective ways of reducing saturated fat. Some people may find that limiting their total fat intake can indirectly help them reduce their saturated fat intake. Replacing saturated fats with carbohydrates can also lower LDL cholesterol, but such a change may raise blood triglyceride (VLDL) levels as well.24 The effect on blood triglycerides can be minimized by limiting added sugars and including fiber-rich foods; ideally, the diet should include generous amounts of whole grains, legumes, fruits, and vegetables.

Blood Cholesterol Levels and CHD Risk

Once a person's level of risk has been identified, much of the treatment focuses on lowering LDL cholesterol. Elevated LDL levels are directly related to the development of atherosclerosis, and clinical studies have confirmed that LDL-lowering treatments can successfully reduce the rates of cardiovascular events.18 CHD is seldom seen in populations that maintain desirable LDL levels. As mentioned earlier, HDL help to protect against atherosclerosis, and low HDL levels often coexist with other lipid abnormalities; thus, a low HDL level is highly predictive of CHD risk. In addition, low HDL levels are usually associated with other CHD risk factors, such as obesity, smoking, inactivity, and insulin resistance. Although having adequate HDL is beneficial, high HDL levels do not necessarily confer additional benefit

Vitamin Supplementation and CHD Risk

Patients are often interested in the potential benefits of using certain types of dietary supplements for reducing CHD risk, particularly B vitamin and antioxidant supplements. Most clinical trials have not been able to confirm any benefits from using these supplements, as described in this section.

Lifestyle Management to Reduce CHD Risk

People at significant risk of heart attack, stroke, or other complications of atherosclerosis are typically advised to modify their health behaviors to reduce their risk (see Box 21-3). The main features of lifestyle management include a healthy dietary pattern, regular physical activity, nonsmoking status, and a healthy body weight (see Table 21-3). The following sections describe lifestyle practices that have been found to improve the lipoprotein profiles of individuals with elevated LDL levels.

Healthy Dietary Pattern

People with elevated LDL levels have been found to benefit from diets that emphasize vegetables, fruit, and whole grains; include fat-free or low-fat milk products, lean meat, poultry, fish, legumes, nontropical vegetable oils, and nuts; and limit intakes of sweets, sugar-sweetened beverages, and foods high in solid fats.20 Acceptable diets include the USDA Food Patterns (described in Chapter 1) and the DASH Eating Plan described later in this chapter (see p. 611-612)

Drug Therapies

People with hypertension usually require two or more medications to meet their blood pressure goals. Using a combination of drugs with different modes of action can reduce the doses of each drug needed and minimize side effects. Most treatments include diuretics, which lower blood pressure by reducing blood volume. Other medications commonly prescribed include calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin-receptor blockers (see Box 21-12); some of these drugs are also used to treat various heart conditions. Drug dosages may need regular adjustment until the blood pressure goal is reached.

Patents with Congestive Heart Failure may need to limit:

Potassium and calcium Sodium and Fluid (correct) Potassium and sodium Fiber and fluid

The DASH Diet emphasizes including adequate amounts of:

Protein, calcium, and iron Potassium, calcium, and magnesium (correct) Phosphorus, magnesium, and selenium Calcium, Vitamin D, and Iron

Regular Physical Activity

Regular aerobic activity reverses a number of risk factors for CHD: it can lower LDL levels, reduce blood pressure, improve insulin sensitivity, promote weight loss, strengthen heart muscle, and increase coronary artery size and tone (see Photo 21-1). Current guidelines recommend at least 30 minutes of moderate-intensity activity on most days of the week.36 Activities that use large muscle groups provide the greatest benefits; such activities include brisk walking, swimming, cycling, stair stepping, and cross-country skiing. If preferred, physical activity can be divided into several sessions during the day. Note that vigorous activity increases the risk of a heart attack or sudden death in individuals with diagnosed heart disease, so sedentary adults may be advised to increase their activity levels gradually

What type of diet would be offered as soon as a MI patient is stable?

Soft diet Low Sodium Liquids (correct) Low saturated fat Clear liquid

The LifeStyle Changes for CHD approach encourages adding the (these) to inhibit cholesterol absorption:

Soluble Fiber Plant Sterols Omega 3 FA A and B (Correct) All of the Above

Soluble Fibers

Soluble, viscous fibers can reduce LDL cholesterol levels by inhibiting cholesterol and bile absorption in the small intestine and reducing cholesterol synthesis in the liver. Good sources of soluble fibers include oats, barley, legumes, and some fruits and vegetables. The soluble fiber in psyllium seed husks, frequently used to treat constipation, is effective for lowering cholesterol levels when used as a dietary supplement.

Stroke Prevention

Stroke is largely preventable by recognizing its risk factors and making lifestyle choices that reduce risk. Many of the risk factors are similar to those for heart disease and include hypertension, elevated LDL cholesterol, diabetes mellitus, cigarette smoking, physical inactivity, aging, and genetic influences.53 Medications that suppress blood clotting reduce the risk of ischemic stroke, especially in people who have suffered a first stroke or a TIA. The drugs typically prescribed include antiplatelet drugs (including aspirin) and anticoagulants such as warfarin (Coumadin). Anticoagulant therapy requires regular follow-up and occasional adjustments in dosage to prevent excessive bleeding.

21.3 Stroke

Stroke is the fifth most common cause of death in the United States and a leading cause of long-term disability in adults. About 87 percent of strokes are ischemic strokes, caused by the obstruction of blood flow to brain tissue.51 Hemorrhagic strokes occur in 13 percent of cases and result from bleeding within the brain, which damages brain tissue. Most ischemic strokes are a result of blood clotting within an artery narrowed by atherosclerosis, but an embolism may also cause a stroke. Hemorrhagic strokes often result from the rupture of a blood vessel that has been weakened by atherosclerosis and chronic hypertension. Hemorrhagic strokes are generally more deadly: more than 33 percent of cases result in death within 30 days.52 Strokes that occur suddenly and are short-lived (lasting several minutes to several hours) are called transient ischemic attacks (TIAs). These brief strokes are a warning sign that a more severe stroke may follow, and they need to be evaluated and treated quickly. TIAs typically cause short-term neurological symptoms, such as confusion, slurred speech, numbness, paralysis, or difficulty speaking. Treatment includes the use of aspirin and other drugs that inhibit blood clotting

On the Dash Diet patients will be eating less:

Sugar, salt, starchy foods Dairy, meat, total fat Red meat, sugar, and saturated fats (correct) Snacks, sweets, and oils

Symptoms of Coronary Heart Disease

Symptoms of CHD usually arise only after many years of disease progression (see Box 21-2). In angina pectoris and heart attacks, pain or discomfort most often occurs in the chest region and may be perceived as a feeling of heaviness, constriction, or squeezing; the pain may radiate to the left shoulder, arms, neck, back, or jaw.14 In angina pectoris, the symptoms are often triggered by exertion and subside with rest; in a heart attack, the pain may be severe, last longer, and occur without exertion. Other symptoms of CHD include shortness of breath, unusual weakness or fatigue, nausea, vomiting, and abdominal discomfort. Women are more likely than men to have a heart condition (or even a heart attack) that is unaccompanied by chest pain or acute symptoms.

Stroke Management

The effects of a stroke vary according to the area of the brain that has been injured (see Box 21-8). Body movements, senses, and speech are often impaired, and one side of the body may be weakened or paralyzed. Early diagnosis and treatment are necessary to preserve brain tissue and minimize long-term disability. Ideally, thrombolytic (clot-busting) drugs should be used within 4½ hours following an ischemic stroke to restore blood flow and prevent further brain damage.54 After patients have stabilized, they are usually started on medications that help to prevent stroke recurrence or complications, including anticoagulants or antiplatelet drugs, antihypertensives, and blood lipid-lowering drugs. Rehabilitation programs typically start as soon as possible after stabilization. Patients must be evaluated for neurological deficits, sensory loss, mobility impairments, bowel and bladder function, communication ability, and psychological problems. Rehabilitation services often include physical therapy, occupational therapy, speech and language pathology, and kinesiotherapy (training to improve strength and mobility). The focus of nutrition care is to help patients maintain nutrition status and overall health despite the disabilities caused by the stroke. The initial assessment should determine the nature of the patient's self-feeding difficulty (if any) and the adjustments required for appropriate food intake. Some patients may need to learn about dietary treatments that improve blood lipid levels and blood pressure. Dysphagia (difficulty swallowing) is a frequent complication and is associated with a poorer prognosis. Difficulty with speech may prevent patients from communicating food preferences or describing the problems they may be having with eating. Coordination problems can make it hard for patients to grasp utensils or bring food from table to mouth. In some cases, tube feedings may be necessary until the patient has regained these skills. Nutrition in Practice 21 describes additional options for people who have disabilities that impair eating ability as a result of a stroke or other condition.

Consequences of Heart Failure

The effects of heart failure depend on the severity of illness: mild cases may be asymptomatic, but severe cases may cause considerable damage to health (see Box 21-14). Heart failure may begin on the left or the right side of the heart, or both sides may fail simultaneously. • Left-sided heart failure. The left side of the heart normally receives blood from the lungs and pumps it to peripheral tissues. A weakened left heart may allow fluid to build up in the lungs (a condition called pulmonary edema), resulting in extreme shortness of breath, limited oxygen for activity, and, in severe cases, respiratory failure. The inadequate blood flow to tissues can result in organ dysfunction. In addition, fluid accumulation within the lungs increases fluid pressure in the right side of the heart, potentially damaging heart tissue and leading to right-sided heart failure. • Right-sided heart failure. The right side of the heart normally receives blood from the peripheral tissues and pumps blood to the lungs. With impaired pumping, fluids can back up into the abdomen and peripheral tissues, potentially causing ascites, liver and spleen enlargement, impaired liver and gastrointestinal function, and swelling in the legs, ankles, and feet. Heart failure often affects a person's food intake and level of physical activity. In persons with abdominal bloating and liver enlargement, pain and discomfort may worsen with meals. Limb weakness and fatigue can limit physical activity. End-stage heart failure is often accompanied by cardiac cachexia, a condition of severe malnutrition characterized by significant weight loss and tissue wasting. Cardiac cachexia may develop due to increased levels of pro-inflammatory cytokines (which promote catabolism), elevated metabolic rate, reduced food intake, and malabsorption. The resultant weakness further lowers the person's strength, functional capacity, and activity levels.

Causes of Atherosclerosis

The factors that initiate atherosclerosis either cause direct damage to the artery wall or allow lipid materials to penetrate its surface. Factors that generally worsen atherosclerosis or lead to complications are those that cause plaque rupture or blood coagulation. The development of advanced atherosclerosis is a long-term process that involves recurrent plaque rupture, thrombosis, and healing at sites in the artery wall.

Dietary Cholesterol

The influence of dietary cholesterol on CHD risk is somewhat unclear; although some research studies have found a relationship between dietary cholesterol and CHD risk, others have not.28 Due to concerns about the potential adverse effects of excessive dietary cholesterol in some people, some guidelines recommend cholesterol intakes of less than 200 milligrams per day for high-risk individuals.29 Cholesterol intakes of women and men in the United States average about 242 and 348 milligrams per day, respectively.30 Eggs contribute about one-quarter of the cholesterol in the U.S. diet, followed by chicken, beef, and cheese. The effect of eggs on CHD risk is controversial. While egg intakes have not been linked to CHD risk in healthy populations, a number of observational studies have found an association in persons with diabetes.31 The optimal number of eggs to include in a heart-healthy diet is undetermined, and different guidelines may be necessary for healthy and high-risk populations.

Drug Therapies for Heart Failure

The medications prescribed for heart failure include diuretics, ACE inhibitors, angiotensin receptor blockers, beta blockers, vasodilators, and digitalis.77 The diuretics are given to reverse or prevent fluid retention. The patient must monitor fluid fluctuations with daily weight measurements and can make small adjustments in the diuretic dose as needed. The other drugs listed help to improve heart and blood vessel function and blood flow.

Fish and Omega-3 Fatty Acids

The omega-3 fatty acids in fatty fish, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may benefit people at risk of CHD by suppressing inflammation, lowering blood triglyceride levels, reducing blood clotting, and stabilizing heart rhythm. In addition, including fish in the diet can reduce CHD risk because fish is low in saturated fat and often replaces meat dishes that contain saturated fat. The American Heart Association and several other health organizations recommend consuming two or more servings of fish per week, with an emphasis on fatty fish.33 It is not clear whether fish oil supplements have effects similar to those of fish consumption. Some of the more recent clinical trials of EPA and DHA supplementation did not result in lower numbers of heart attacks or heart disease deaths, and researchers have suggested that the benefits of supplementation may be difficult to distinguish from those of other treatments or lifestyle practices.

Shear Stress/Hypertension

The stress of blood flow along artery walls—called shear stress—can cause physical damage to arteries.4 Hypertension (high blood pressure) intensifies the stress of blood flow on arterial tissue, provoking a low-grade inflammatory state that may stimulate plaque formation or progression.

Trans Fats

Trans fats can raise LDL levels, and when they replace saturated fats in the diet (as when stick margarine replaces butter), they may also reduce HDL levels.27 Furthermore, trans fats may raise CHD risk by promoting inflammation and endothelial dysfunction. Thus, the trans fat intake should be kept as low as possible. Most sources of trans fats are products made with partially hydrogenated vegetable oils; examples include baked goods such as crackers, cookies, and doughnuts; snack foods such as potato chips and corn chips; and fried foods such as french fries and fried chicken. In recent years, food manufacturers have reformulated many food products so that they contain little or no trans fat. In some cases, however, the trans fats have been replaced with saturated fat sources, so consumers should read labels carefully to avoid both types of cholesterol-raising fats

An atherogenic diet is an independent risk factor for CHD

True

The main dietary feature of Lifestyle Changes for CHD is

Weight Reduction Adding soluble fiber Reducing saturated fat and cholesterol (correct) Limiting sodium

Abnormal Blood Lipids

When LDL levels are high, they are actively taken up and retained in susceptible regions in the artery wall. Elevated levels of very-low-density lipoproteins (VLDL) can also promote atherosclerosis, either by influencing the production of other atherogenic lipoproteins or by causing molecular changes in endothelial cells and macrophages that promote inflammation or plaque development.6 Because high-density lipoproteins (HDL) remove cholesterol from circulation and contain proteins that inhibit inflammation, LDL oxidation, and plaque accumulation, low HDL levels can contribute to the development of atherosclerosis as well.7 LDL vary in size and density, and these LDL subtypes have differing effects on heart disease risk. The smallest, most dense LDL can slip into artery walls easily and are more atherogenic than the larger, less dense LDL.8 Furthermore, people who have small, dense LDL frequently have elevated VLDL and low HDL levels. This lipoprotein profile is especially prevalent in individuals with the metabolic syndrome and type 2 diabetes. Elevated concentrations of a variant form of LDL called lipoprotein(a) have been found to speed the progression of atherosclerosis and to raise the risk of various types of CVD.9 Lipoprotein(a) levels are primarily genetically determined and are influenced to only a minor degree by age and environmental factors

thrombus

a blood clot formed within a blood vessel that remains attached to its place of origin

coronary heart disease (CHD)

a chronic, progressive disease characterized by obstructed blood flow in the coronary arteries; also called coronary artery disease

angina pectoris

a condition caused by ischemia in the heart muscle that results in discomfort or dull pain in the chest region. The pain often radiates to the left shoulder, arms, neck, back, or jaw

cardiovascular disease (CVD)

a general term describing diseases of the heart and blood vessels

aneurysm

an abnormal enlargement or bulging of a blood vessel (usually an artery) caused by weakness in the blood vessel wall

embolus

an abnormal particle, such as a blood clot or air bubble, that travels in the blood

plaque

an accumulation of fatty deposits, fibrous connective tissue, and smooth muscle cells in the walls of blood vessels

atherosclerosis

an arterial disease characterized by a buildup of lipids and fibrous scar tissue on the inner walls of arteries

myocardial infarction

death of heart muscle caused by a sudden obstruction in blood flow to the heart; also called a heart attack

peripheral artery disease

impaired blood flow in the arteries of the legs; may cause pain and weakness in the legs and feet, especially during exercise. The presence of pain or discomfort while walking is known as intermittent claudication

ischemia

inadequate blood supply within a tissue due to obstructed blood flow

stroke

sudden death of brain cells due to impaired blood flow to the brain or rupture of an artery in the brain; also called a cerebrovascular accident

thrombosis

the formation or presence of a blood clot in blood vessels. A coronary thrombosis occurs in a coronary artery, and a cerebral thrombosis occurs in an artery that supplies blood to the brain

embolism

the obstruction of a blood vessel by an embolus, causing sudden tissue death