Cardiovascular diseases are the leading cause of illness and death in the United States. The majority of cases stem from atherosclerosis, a condition in which cholesterol, fat, and fibrous tissue build up in the walls of large and medium-sized arteries.
In coronary heart disease (CHD), the arteries to the heart muscle (myocardium) are narrowed. Reduced blood supply to the heart can result in chest pain (angina pectoris) or other symptoms, typically triggered by physical exertion. If a narrowed blood vessel is completely blocked by a blood clot, the area of the heart just beyond the blockage is denied oxygen and nourishment, resulting in a heart attack (myocardial infarction).
Like other degenerative disease processes, atherosclerosis can take years to develop. Diet is implicated because the deposits on arterial walls contain high levels of fat and cholesterol. Studies of both humans and animals have shown links between dietary habits and atherosclerosis.
At least nine risk factors can help predict the likelihood of CHD: heredity, being male, advancing age, cigarette smoking, high blood pressure, diabetes, obesity (especially excess abdominal fat), lack of physical activity, and abnormal blood cholesterol levels. The more risk factors a person has, the greater the likelihood of developing heart disease. Heredity, gender, and age cannot be modified, but the others can be influenced by the individual's behavior.
Several of these risk factors are interrelated. Obesity, lack of exercise, and cigarette smoking can raise blood pressure and adversely influence blood cholesterol levels. Several studies suggest that exposure to environmental tobacco smoke ("passive smoking") also increases the risk of developing heart disease [1-2]. Some authorities believe that emotional stress is a risk factor, but the evidence for this is not clear-cut.
Exercise offers many benefits. People who exercise tend to live longer and have less cardiovasular disease than those who do not . A well-designed exercise program can increase stamina and endurance, lower blood pressure, improve blood cholesterol levels, help with weight control, help lower abnormal blood sugar levels, reduce stress, improve sleep, and help prevent osteoporosis. Exercising vigorously is advantageous, but even moderate exercise has important protective effects .
Blood cholesterol levels should be determined by a screening test called lipid analysis (or lipid profile), which measures the levels of low-density lipoproteins (LDL), high-density lipoproteins (HDL), and triglycerides, as well as the total blood cholesterol levels. If LDL is too high or HDL is too low, a medically supervised corrective program should be started. The National Cholesterol Education Program recommends measuring cholesterol levels at least once every five years . People with abnormal levels should have them measured more often than those who do not.
The U.S. Surgeon General's Office has extensive information on smoking cessation.
- Steenland K. Passive smoking and the risk of heart disease. JAMA 267:94-99, 1992.
- Kawachi I and others. A prospective study of passive smoking and coronary heart disease. Circulation 95:2374-2379, 1997.
- Blair SN and others. Changes in physical fitness and all-cause mortality: A prospective study of healthy and unhealthy men. JAMA 273:1093-1098, 1995.
- Lee, I, Hsich C, Paffenbarger RS. Exercise intensity and longevity in men. JAMA 273:1179-1184, 1995
- Grundy SM and others. Summary of the second report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults. JAMA 269:3015Â3023, 1993.