Cardiovascular Disease and Physical Activity

The Leading Causes of Deathin the United States in 2003

Data from American Heart Association, 2006.

Prevalence of Cardiovascular Disease

In 2003• >1.2 million heart attacks• ~480,000 deaths due to heart attacks• ~1 in 5 deaths was attributable to CAD• 1 in 2.7 deaths was attributable to cardiovascular

diseases• ~467,000 coronary artery bypass surgeries• ~1,244,000 angioplasties• Over 2,000 heart transplants

Factors Contributingto Decline in Deaths

• Improved public awareness (e.g., concept of risk factors)

• Increased use of preventive measures, including lifestyle changes

• Better and earlier diagnosis• Improved drugs for specific treatment• Better emergency and medical care

Cardiovascular Diseases• Coronary artery disease (CAD)• Hypertension • Stroke• Heart failure• Peripheral vascular disease• Valvular, rheumatic, and congenital heart disease

The Leading Causes of DeathFrom Cardiovascular Disease

Data from American Heart Association, 2006.

Coronary Artery DiseaseCoronary artery disease (CAD): involves atherosclerosis in the coronary arteriesAtherosclerosis: progressive narrowing of the arteries due to plaque formationIschemia: a deficiency of blood flow to the heart caused by CADAngina pectoris: chest painMyocardial infarction: a heart attack due to ischemia leading to irreversible damage and necrosis

Atherosclerosis

• Not a disease of the aged• Pathological changes in the blood vessels begin in

infancy and progress during childhood• Rate of progression is determined by genetics and

lifestyle factors (smoking, diet, physical activity, and stress)

Progressive Formation of Plaquein a Coronary Artery

Hypertension

• About one in every three adult Americans has hypertension

• Causes the heart to work harder• Strains the systemic arteries and arterioles• Can cause pathological hypertrophy of the heart • Can lead to atherosclerosis, heart attacks, heart failure,

stroke, and renal failure

Stroke• Cardiovascular disease that affects the cerebral arteries• Ischemic stroke

– Cerebral thrombosis: a blood clot forms in a cerebral vessel, most often at the site of atherosclerotic damage

– Cerebral embolism: an undissolved mass of material breaks loose from another site in the body and lodges in a cerebral artery

• Hemorrhagic stroke– Cerebral hemorrhage: rupture of one of the cerebral arteries– Subarachnoid hemorrhage: surface vessel on the brain

ruptures, bleeding into the space between the brain and the skull

Congestive Heart Failure

• Heart muscle becomes too weak and cannot maintain adequate cardiac output

• It can result from damage to heart from: hypertension, atherosclerosis, valvular heart disease, viral infections, and heart attack

• Blood backs up in veins, causing systemic and pulmonary edema

• Can progress to irreversible damage, requiring a heart transplant

Pathophysiology of CAD

Early theory: 1. Local injury induces dysfunction of the endothelium2. Blood platelets and monocytes adhere to the exposed

connective tissue3. Platelets release platelet-derived growth factor that

promotes smooth muscle cell migration from the media to the intima

4. Plaque forms at the site of injury5. Lipids are attracted to the plaque

Changes in the Arterial Wall With Injury

Pathophysiology of CAD

Newer theory:1. Monocytes attach themselves to endothelial cells2. Monocytes differentiate into macrophages and ingest

oxidized LDL-C, becoming enlarged foam cells to form fatty streaks

3. Smooth muscle cells accumulate under the foam cells4. Endothelial cells slough off, exposing underlying

connective tissue5. Platelets attach to exposed tissue

Illustration of Fissure or Rupture of an Unstable Plaque in a Coronary Artery

Pathophysiology of HypertensionRisk factors – Heredity, including race – Increasing age and male sex– Sodium sensitivity– Excessive alcohol consumption and use of tobacco

products– Obesity and overweight– Diabetes or insulin resistance– Physical inactivity– Oral contraceptives– Pregnancy– Stress

Primary Risk Factors for CAD

• Tobacco smoking• Hypertension• Abnormal blood lipids and lipoproteins• Physical inactivity• Obesity and overweight• Diabetes and insulin resistance

Controllable Risk Factorsfor Hypertension

• Insulin resistance• Obesity and overweight• Diet (sodium, alcohol)• Use of oral contraceptives• Use of tobacco products• Stress• Physical inactivity

Metabolic Syndrome

• Hypertension, coronary artery disease, obesity, and diabetes are linked through the common pathway of insulin resistance

• Metabolic syndrome, syndrome x, and insulin resistance syndrome are terms used to describe this interrelationship

• Obesity and/or insulin resistance could be the trigger that starts metabolic syndrome

Percentages of the U.S. Population at Increased Risk for Coronary Artery

Disease Based on Primary Risk Factors

Reproduced from Caspersen, C.J.: Physical activity and coronary heart disease. Physicians Sportsmedicine 1987; 15(11): 43-44.

Epidemiological Evidence

• Physical inactivity doubles the risk of CAD• Low-intensity physical activity is sufficient to reduce the

risk of this disease• Health benefits do not require high-intensity exercise• More vigorous exercise likely provides even greater

benefits

Aerobic Training Adaptations

• Produce larger coronary arteries which increases the capacity for blood flow to the heart

• Increased cardiac pumping capacity• Improved circulation in the heart• Reduce blood pressure (~7 mmHg) in individuals with

mild to moderate hypertension• Improves cholesterol ratio• Weight reduction• Improves insulin sensitivity• Stress management

Reducing the Risk of Hypertension Through Exercise

• People who are active and those who are fit have reduced risk for developing hypertension

• Increased plasma volume that accompanies physical training does not increase blood pressure due to training-induced increased capillarization and increased venous capacity

• Resting blood pressure decreases by training in people with hypertension

Risk of Heart Attack and Death During Exercise

• Deaths during exercise are rare, although typically highly publicized

• Deaths during exercise in people over 35 usually are caused by a cardiac arrhythmia resulting from atherosclerosis

• Deaths during exercise in people under age 35 are usually caused by hypertrophic cardiomyopathy, congenital coronary artery abnormalities, aortic aneurysm, or myocarditis

Risk of Primary Cardiac Arrest During Vigorous Exercise and at Other Times

Throughout a 24 h Period

Data from D.S. Siscovick et al., 1984, "The incidence of primary cardiac arrest during vigorous exercise," New England Journal of Medicine 311: 874-877.