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Imagine a gruel-like sludge coating the inside of your arteries and then hardening to block the flow that keeps your heart beating and you alive. This is what happens in atherosclerosis, which affects about 14 million Americans and can lead to coronary artery disease (CAD). The Greek roots of the word atherosclerosis well describe the process within affected arteries."Athero" means gruel or paste and"sclerosis" means hardness. Untreated, the atherosclerotic process can completely occlude, or block, arteries. When atherosclerosis causes severe or total occlusion, chest pain called angina or myocardial infarction (heart attack) can occur.
Many of the important risk factors in atherosclerosis are modifiable, or within your control. A smaller number of these factors are outside your control. Reducingor better yet, eliminatingthe risk factors you can control means significantly reducing your risk of atherosclerosis and myocardial infarction. Being aware of the risk factors you cannot change can increase your vigilance for the first signs and symptoms of CAD.
Risk Factors You Cannot Change
While many risk factors are within your control, some are not. There is good reason to be aware of risk factors you cannot change: Knowing your risk can make you more diligent in reducing those risk factors that you can control. For example, if you are a man over the age of 55, you should be especially vigilant in reducing blood cholesterol and controlling hypertension (high blood pressure).
Risk factors that you cannot change include the following:
Risk Factors You Can Change
High Blood Cholesterol
Prevention is particularly powerful in the case of blood cholesterol. For every 1 percent reduction in your total blood cholesterol reading, you cut your risk of CAD by 2 percent. For example, if your cholesterol reading is 200 mg/dL (milligrams of cholesterol per deciliter of blood), lowering it by 1 percent to 198 mg/dL drops your risk of clogged arteries by 2 percent. Lowering cholesterol 10 percent (from 200 mg/dL to 180 mg/dL, for example) cuts your risk of CAD by 20 percent. Lowering the low-density lipoprotein (LDL) cholesterol reading is even more important than lowering overall cholesterol (see Understanding Cholesterol, page 23).
To reduce the risk of CAD your total cholesterol level should be less than 200 mg/dL, your LDL cholesterol level should be less than 130 mg/dL (less than 100 if you already have CAD), and your level of high-density lipoprotein (HDL) cholesterol should be greater than 45 mg/dL for men and greater than 55 mg/dL for women.
The first way to decrease blood cholesterol levels should always be dietary changes and exercise (see Dietary Guide to Heart Health, page 28 and Exercise, page 39). But if cholesterol levels do not respond to these lifestyle modifications, your doctor may prescribe a cholesterol-lowering medication. Cholesterol-lowering medications include the following:
High Blood Triglycerides
When blood cholesterol levels are checked through a lipid profile test, blood triglyceride levels are also measured. Triglycerides are the form in which fat from food is carried through the bloodstream to be stored. Blood triglycerides become elevated if too many calories of any type are eaten: The body converts excess sugar and alcohol calories into triglycerides for storage as fat. High triglyceride levels can increase a persons chance of developing CAD. An optimal triglyceride level is less than 200 mg/dL.
One in four Americans, some 50 million adults, has hypertension (high blood pressure) although up to half of them do not know it until they suffer a stroke or myocardial infarction. This is why hypertension is called the silent killer. An additional 34 million adults have high normal blood pressure. High normal blood pressure is far more serious than it sounds: At least one-third of all myocardial infarctions and strokes occur in people with high normal blood pressures. Fewer than half of all Americans have optimal blood pressure readings (see Optimal Blood Pressure, page 24).
High Blood Sugar
Uncontrolled diabetes mellitus doubles a mans risk and triples a womans risk for CAD. Diabetes is a chronic disorder in which the pancreas either cannot produce or adequately utilize insulin, the hormone that breaks down digested sugars. Diabetes can take one of two forms: type 1 diabetes, previously called insulin-dependent diabetes mellitus or juvenile diabetes, and type 2 diabetes, formerly known as noninsulin-dependent diabetes mellitus or adult-onset diabetes.
Some people have a condition called impaired glucose tolerance. While they do not have abnormally high blood sugars, their bodies have to work much harder to keep blood sugars in the normal range by pumping out excessive amounts of insulin. In this process, they suffer some of the same symptoms as do people with diabetes.
Maintaining a lean body weight and exercising regularly reduces the risk of developing type 2 diabetes. Losing weight, exercising, and following a diet planned by a registered dietitian can normalize blood sugars if type 2 diabetes does develop.
Low levels of three B vitaminsB12, B6, and folic acidcan increase CAD risk. Recent evidence suggests that these vitamins can control blood levels of homocysteine, a naturally occurring body amino acid. Studies have found that having high levels of homocysteine in the blood can significantly increase risk of CAD.
Although some people have a genetic tendency to high homocysteine levels, most people can keep levels in check by eating a balanced diet that includes milk products, lean meats, fish, poultry, fruits, green leafy vegetables, and whole grains, foods that contain B vitamins. Your doctor may also advise taking supplemental vitamins. It is nearly impossible to get the daily requirements of folic acid (400 IU) through diet alone.
Excess body weight greatly increases a persons risk of developing CAD, largely by increasing hypertension and cholesterol levels and impairing glucose tolerance. Take the example of a lawnmower engine, which is powerful enough to cut grass, but does not have enough energy to propel a car. The one-third of Americans who are seriously overweight place great demands on their hearts every day. Their hearts are continually stressed to meet the physical requirements of excess body weight. The strain can result in high blood pressure, a risk factor for CAD. Heavier people also tend to be sedentary, which further increases the risk of CAD.
Two methods are used to calculate obesity. Central adipositythe tendency of some people, particularly men, to gain weight around the midsectionincreases a persons risk of developing CAD. Excess weight in the midsection triggers metabolic changes that cause significant abnormalities in cholesterol and a higher incidence of impaired glucose tolerance and type 2 diabetes, especially in women. The waist-hip ratio (WHR) is used to measure central adiposity. WHR is the waist circumference divided by the hip circumference. A WHR higher than 1.0 in men and 0.9 in women is considered high risk.
The body mass index, or BMI, also provides a measure of obesity. The National Heart, Lung and Blood Institutes Obesity Education Initiative defines being overweight as having a BMI over 25 and considers people with a BMI greater than 30 as obese (see Calculating Body Mass Index, below).
The human body is meant to be activeespecially for the hearts sake. Like any other muscle, the heart cannot be as strong as it needs to be without adequate exercise. Exercise confers many other significant benefits to the heart, including fighting the bodys tendency to form tiny blood clots in the bloodstream, which can eventually develop into a larger clot that can cause a myocardial infarction. Exercise raises the bodys percentage of HDL cholesterol, which protects the heart. Engaging in regular exercise also helps to manage stress and anger.
Uncontrolled Stress or Anger
While stress and anger are a part of life, the reaction to them is what mattersespecially as they impact on CAD risk. The cascade of physiologic responses set off by stress and anger is the same emergency response that protected prehistoric people from predators: the fight-or-flight response.
Sensing dangerwhether it be a charging woolly mammoth or a screaming bossthe body releases epinephrine (adrenaline) and other hormones that make the heart beat faster and that energize the body. People who are chronically stressed tend to secrete more of a hormone called cortisol, which can raise blood pressure and program the body to retain fluid. These physiologic changes increase the risk of myocardial infarction.
Each year, cigarette smoking accounts for nearly 200,000, or one-fifth, of all deaths from heart disease in the United States90,000 of which are due to atherosclerosis. Smokers have a two- to fourfold greater incidence of CAD and about a 70 percent higher death rate from CAD than do nonsmokers.
Inhaling tobacco smoke causes immediate, negative effects on the heart and blood vessels. The impact is cumulative. Some of these ill effectsand reasons to stop smokinginclude:
Smoking increases CAD risk by several powerful mechanisms. It increases levels of free fatty acids in the bloodstream and also increases levels of a cholesterol component called very-low-density lipoprotein (VLDL), which raises LDL cholesterol and decreases HDL cholesterol (see Understanding Cholesterol, page 23). Smoking damages the arterial lining, making it an attractive site for blood fats and platelets to accumulate, which either starts or encourages the process of atherosclerosis.
In addition, smoking raises blood pressure, which contributes to heart disease risk. Smoking also causes another abnormality in blood pressure, called blood pressure variability, which is even more damaging. Finally, one ingredient of tobacco smoke, carbon monoxide, exerts a negative effect on the heart by limiting the bloods ability to carry oxygen.
Passive smokingtaking in second-hand smokeis also a powerful risk factor. Continual exposure to second-hand smoke nearly doubles a persons risk of having a myocardial infarction, and the Environmental Protection Agency calls environmental tobacco smoke a serious and substantial health risk for nonsmokers.
How to Stop Smoking
The highly addictive nature of smoking makes quitting a difficult proposition. Behaviorists point out that having a plan increases the chances of long-term success:
When you first quit smoking, you will likely crave cigarettes, be irritable, feel very hungry, cough often, get headaches, or have difficulty concentrating. These symptoms of withdrawal occur because the body is adjusting to the lack of nicotine, the addictive agent in cigarettes.
Withdrawal symptoms are temporary. They are strongest right after quitting, and generally disappear within 2 weeks. Withdrawal symptoms are far easier to treat than the major diseases that smoking can cause.
A relapse is not a reason to lose hope. Seventy-five percent of people who quit subsequently relapse. Most smokers quit three times before they are successful.
Dietary Guide to Heart Health
Managing the amount and type of dietary fat you eat is a key strategy in lowering blood cholesterol levels and reducing CAD risk. Two simple strategiessubtract and substitutewill help in the wise management of dietary fat.
The American Heart Association and the National Cholesterol Education Program recommend limiting fat calories to 30 percent of a days total caloric intake. The Cleveland Clinic Heart Center Preventive Cardiology and Rehabilitation Program recommends holding fat calories to 15 to 25 percent of a days total calorie intake.
Some evidence suggests that people with diets that contain very low amounts of fat give themselves a great advantage: Not only do they lower serum cholesterol and prevent future development of the plaque that blocks arteries, they also reverse or clear away plaque that already exists. This is called reversing stenosis.
People who have a genetic predisposition to CAD are very sensitive to dietary factors. For them, holding dietary fat to the 15 percent level is especially important. Finally, reducing dietary fat makes weight control easier, because fats are calorically dense: Each gram of fat has two and a half times as many calories as the same amount of proteins and carbohydrates.
Choosing heart-healthier fat calories is as important as cutting down on the amount of fat you consume. There are three main types of fatty acids that make up dietary fat: saturated, polyunsaturated, and monounsaturated. Any food that contains fat has all three types of fatty acids, but generally one type predominates; dietary fats are generally called by the name of the predominating fat. For example, olive oil is called a monounsaturated fat because 75 percent of its fatty acids are monounsaturated. However, it also contains some polyunsaturated fat and a little saturated fat.
Fats that are predominantly poly- and monounsaturated fatty acids are liquid at room temperature, and saturated fats are solid. Picture a bottle of liquid olive oil versus the white waxy layer of saturated fat on a slab of roast beef.
As a rule, fats of plant origin, such as vegetable oils, are almost entirely poly- and monounsaturated (the only exceptions are coconut and palm oil, which are primarily saturated fat). Animal fatsthose in dairy foods, beef, pork, and chickenare predominantly saturated.
This clear animal/plant distinction is significant in choosing a healthier fat. Vegetable fats are always better for the heart than are animal fats; mono- and polyunsaturated fats are much healthier choices than are saturated fats.
Saturated fat is the hearts greatest food enemy. It raises blood cholesterol levels, especially of LDL cholesterol. One way that saturated fat is thought to do this is by impairing the livers ability to remove cholesterol. Normally, LDL receptors at the end of liver cells snag LDL cholesterol as it flows by; the LDL particles are then packaged for removal from the body through the intestinal tract. Saturated fat both reduces the number of LDL receptors and impairs their efficiency.
The best way to limit saturated fat intake is by cutting back on the number of meat and poultry meals and by reducing serving sizes of these foods. Of seven dinner meals, fish can be served for at least two, nonmeat entrees for at least two, and the remaining three meals can be divided between meat and poultry. According to the United States Department of Agriculture (USDA) guidelines, when beef, pork, or chicken is served, a serving should equal 3 ouncesa portion equal to the size and depth of a deck of playing cards.
Vegetable sources of proteinblack beans, lentils, tofu (soybean curd), tempeh (a fermented, textured soybean product), and other legumescan be served for every lunch. It is generally thought that having more plant-based than animal-based meals is one of the healthiest steps to take to reduce CAD risk.
Dairy foodsmilk, sour cream, cream cheese, and yogurtcan be enjoyed in their nonfat or low-fat versions. You can also include cheese in your diet in a fat-free or reduced-fat version; if you do not enjoy the taste or texture of fat-free cheese, use a reduced-fat version and limit your serving size to an ounce or two a maximum of three times a week.
Limiting convenience and snack foods also cuts down on saturated fat. Some of these foods are cooked in saturated fats (such as lard), and others are cooked in coconut or palm oil. Even baked varieties are often coated with unhealthy fats.
Monounsaturated fats are the heart-friendliest fats. Substituted for saturated and trans-fats (see Trans-Fatty Acids, page 30) and limited in quantity, monounsaturated fats may lower LDL-cholesterol. This is also true for the third type of fat, polyunsaturated fats. Monounsaturated fats, however, offer another advantage over polyunsaturated fats: They seem to protect against LDL oxidation (see Oxidation: Bad Cholesterol Made Worse, page 30). Whenever you use added fat, such as an oil, in baking or cooking, choose a monounsaturated one such as olive or canola. But also remember the first rule about fats: reduce the amount of fat you use in any recipe (see Calorie-and Fat-Reducing Cooking Techniques, page 255).
How daily calories are consumed may be as important to heart health as the number of calories that are eaten. Designing a diet with the appropriate number of calories is pivotal in losing weightand slimming down may be the single most important action an overweight person can take to reduce heart disease risk. But how daily calories are divided may also influence CAD risk.
A limited amount of research suggests that people who eat several small meals throughout the day have less significant rises in LDL or cholesterol than do people who eat three or fewer large meals.
As people age, the body loses its fat-burning efficiency. The energy-burning hormones become less competent with age. Insulin, the hormone that allows sugar in the blood to enter cells, becomes less efficient with age. As a result, the body must make more insulin to let the same amount of sugar into cells. Increased circulating insulin causes the body to store sugar as fat.
This does not mean that everyone must grow heavier with age. The body is better able to burn smaller calorie bundles. Hormones, especially insulin, work more efficiently with small amounts of calories at one time, and are less likely to turn calories into fat.
The practical advice is easy: Eat six smaller meals throughout the day rather than three larger meals. An easy way to do this is to plan three meals and then split them into sixthis helps to avoid eating junk food at snack times.
How many total calories should you consume in a day? Weight loss can be achieved with no less than 1,500 daily calories. Taking in fewer than 1,500 calories can backfire, leading to overwhelming hunger that can cause bingeing. It is nearly impossible to get all the nutrients the body needs on fewer than 1,500 calories, and such a regime can lead to weakness and fatigue.
The body has a strong ability to preserve itself: Sensing a calorie deprivation, it lowers metabolism. This is why it seems so difficult to lose weight at lower calorie intakesthe body expends less energy and so burns less fat.
The news about caffeine and the heart has been confusing. Caffeine is a stimulant and can cause the heart to beat faster or to skip a beat or two, especially in the presence of heart disease. If you notice this after drinking coffee, discuss it with your doctor, who may advise you to switch to decaffeinated coffee, tea, and soft drinks.
Two issues are relevant in evaluating the effect of coffee on heart health: caffeine and how the coffee is prepared. The long-running debate about caffeine and heart disease was finally settled by researchers at Harvard University, who found that caffeine did not affect heart disease risk in more than 85,000 women between the ages of 34 and 59.
There is some suggestion, however, that coffee prepared without a paper filter may adversely affect blood cholesterol levels. Paper filters trap oils from coffee beans, which are thought to drive up cholesterol levels. Espresso is one type of coffee prepared without a paper filter. If you have CAD and drink coffee prepared without a paper filter, discuss this with your doctor.
While caffeine may not increase the risk of CAD, it may raise both systolic and diastolic blood pressures significantly, especially in people with hypertension. Rises in blood pressure are noted even in people who drink coffee regularly and seem to be more profound with increasing age. People with hypertension should discuss their caffeine intake with their doctors.
You may have heard that red wine is good for the heart. The truth is that the advice about alcohol and heart disease is complicated. Perhaps the most important message is that although a little alcohol may be good for the heart, too much increases cardiovascular problems, including heart rhythm abnormalities and heart failure.
What is too much alcohol? Experts think that anything more than one drink is probably too much. Epidemiological (population-based) data clearly reveal that the benefit of alcohol is more evident among light to moderate drinkers.
A prevalent theory thought to explain alcohols ability to reduce heart disease focuses on HDL cholesterol. Alcohol seems to raise the level of HDL cholesterol, thereby helping to reduce cholesterol buildup on arterial walls. Another possibility is that alcohol decreases platelet aggregation, or renders platelets less sticky and therefore less likely to clump together. Alcohol also seems to encourage the body to produce greater amounts of tissue plasminogen activator, a chemical that helps break up the tiny clots that continuously form in the bloodstream.
Should alcohol consumption be limited to red wine? Probably not, although red wine may offer benefits beyond its alcohol content. The grapes from which red wine is made are high in flavonoids, a type of phytochemical or health-promoting plant substance. Flavonoids are powerful antioxidants, which protect against heart disease (see Oxidation: Bad Cholesterol Made Worse, page 30). It is not necessary to drink an alcoholic beverage to receive the benefits of flavonoids: A wide variety of fruits and vegetables offer rich amounts. Apples, onions, and green beans are flavonoid-rich choices; green and black tea are also very high in this phytochemical.
The best advice about alcohol:
Adopting a vegetarian diet makes it much easier to achieve the dietary recommendations that reduce CAD risk. It is important to be aware, however, that a vegetarian diet is not necessarily synonymous with a low-fat diet.
Some foods included in a vegetarian diet are high in saturated fats. Cheese and other dairy foods tend to be the worst offenders. Just 3 ounces of cheese, 1 cup of 2 percent cottage cheese, and 3 cups of 2 percent milk tally 886 calories, 47 percent of which are fat (including nearly 30 grams of saturated fat). Substituting low-fat soy cheese, nonfat milk, and nonfat cottage cheese lowers calories to 595 and fat to 16 percent (and less than a gram of saturated fat).
The heart-saving essence of vegetarian diets centers on vegetable sources of protein, which offer advantages over animal protein (beef, chicken, and pork). Vegetable protein is naturally very low in fatand almost void of saturated fatand has no cholesterol. The grams of protein in a 2-ounce ground-beef patty come with an unwelcome 12 fat grams, 4 of which are saturated. If the beef is traded for 1 cup of black beans for the same amount of protein, fat is cut to 2 grams and saturated fat to nothing at all; cholesterol drops to 0 from 57 grams. The same serving of black beans is also rich in other nutrients: 14 grams of fiber, lots of folate, and extra calcium.
Fish Oil and Omega-3 Fatty Acids
Inuits (Eskimos) in Greenland revealed to the world that eating fish may decrease CAD risk. Research has consistently uncovered the same association: Death from heart disease is less likely among people who eat at least some fish than among those who do not.
Surprisingly, the fat in fish provides most of the benefit. Fish contain a type of polyunsaturated fatty acid called omega-3. Two omega-3 fatty acids are especially abundant in fish: eicosapentaenoic acid and docosahexaenoic acid.
These fatty acids help fish adapt to the cold water in which they live; they are also thought to confer the health benefits that fish-eaters realize. Omega-3 fatty acids stop the bodys immune system from working overtime by slowing the production of prostaglandins, leukotrienes, and thromboxanes.
While the body needs some of these chemicals to function normally, too-high concentrations of them can cause problems: The right amount helps blood vessels contract and relax appropriately to control blood pressure, but too much makes blood vessels contract too forcefully, driving up blood pressure. An overload of these chemicals also encourages platelets to aggregate overzealously, a risk factor for CAD.
Omega-3 fatty acids raise HDL cholesterol, and eating fish may keep HDL cholesterol from dropping, as can occur on a low-fat diet.
The oil in fish may also keep the heart beating in a healthy rhythm. Disruptions in the hearts electrical conducting system, which keeps the heartbeat even and steady, are called arrhythmias (see Chapter 7, Rhythm Disorders). While some arrhythmias are harmless, others are dangerous and can cause the heart to stop beating altogether (cardiac arrest). There is increasing evidence that omega-3 fatty acids may guard against dangerous arrhythmias, fortifying heart muscle against unstable beats. In a recent study, people who ate enough fish to consume 5.5 grams of omega-3 fatty acids in a monthjust one 3-ounce serving of salmon weeklyhad half the risk of cardiac arrest as people who consumed no omega-3.
Fish may also offer some protection for people who have already suffered one myocardial infarction. Evidence suggests that including two meals of fish (each about 3 ounces) a week may reduce the chances of suffering a second, fatal myocardial infarction. Evidence also suggests that eating fish may keep arteries from closing after angioplasty, a nonsurgical procedure that opens blocked vessels in the heart.
If eating fish is so good for the heart, are fish-oil capsules recommended? Unless a doctor prescribes fish-oil capsules for specific metabolic issues, it is best to rely on eating fish. Fish-oil capsules are a concentrated source of fat calories. While some fish fat is good, too much can cause an elevation in LDL cholesterol and lead to weight gain. Taking fish-oil capsules and then eating a hamburger has no benefitthe negative effects of eating too much red meat and saturated fat cannot be erased with a pill.
If you do not like fish or have a hard time fitting two fish meals into your weekly eating plan, there is an alternative: Flaxseed is high in omega-3 oils. Add flaxseed to bread recipes, sprinkle it on cold and hot cereals, or stir it into juice. Use ground or milled flaxseed, as the body cannot digest the whole seedit passes through the body unabsorbed. However, avoid flaxseed oil, a concentrated source of calories that can negate the benefits of a nutritious meal. Arugula, a peppery-tasting salad green, is also high in omega-3 fatty acids.
|Chapter 1||How the Heart and Circulatory System Work||1|
|Chapter 2||Keeping the Heart Healthy||19|
|Chapter 3||What Is Heart Disease?||45|
|Chapter 4||Diagnosing Heart Disease||51|
|Chapter 5||Coronary Artery Disease||81|
|Chapter 6||Diseases of the Heart Valves||109|
|Chapter 7||Rhythm Disorders||133|
|Chapter 8||Heart Failure||157|
|Chapter 9||Diseases of the Blood Vessels||183|
|Chapter 10||Pediatric and Congenital Heart Disease||205|
|Chapter 11||Recuperation and Rehabilitation After Heart Surgery||231|
|Chapter 12||New Approaches for a Heart-Healthy Household||245|
|Chapter 13||Cardiac Research||263|