Cardiovascular Disease and Physical Activity

Cardiovascular Disease and Physical Activity
Chapter 21 Cardiovascular Disease and Physical Activity

Chapter 21 Overview Forms of cardiovascular disease
Understanding disease process Determining individual risk Reducing risk through physical activity Risk of heart attack and death during exercise Exercise training and rehabilitating patients with heart disease

Introduction to Cardiovascular Disease
Cardiovascular disease leading cause of serious illness and death in United States Affects over 80 million Americans Accounts for 1/3 of all US deaths annually Over $500 billion in annual costs

Figure 21.1

Introduction to Cardiovascular Disease
In 2006 alone, in the United States 448,000 bypass surgeries 1,313,000 coronary angioplasties 2,200 heart transplants Death rate steadily declining since 1960s Improved public awareness and lifestyle changes Better and earlier diagnosis Better treatment options A major health concern worldwide

Table 21.1

Forms of Cardiovascular Disease
Coronary heart disease (CHD) Hypertension Stroke Heart failure Other (peripheral, valvular, congenital)

Forms of Cardiovascular Disease: Coronary Heart Disease
Accounts for half of cardiovascular deaths Progressive narrowing of coronary arteries Fatty plaque formation Atherosclerosis Blood supply to myocardium compromised Myocardial ischemia  angina pectoris Leads to myocardial infarction (MI) Heart attack Irreversible heart muscle cell death due to lack of O2

Figure 21.2

Forms of Cardiovascular Disease: Coronary Heart Disease
Atherosclerosis begins early in life Fatty streaks appear in infancy, childhood Fatty streaks appear in coronary arteries in teens Fibrous plaques develop in 20s Combination of genetics and lifestyle

Forms of Cardiovascular Disease: Hypertension
High blood pressure Systolic ≥140 mmHg, diastolic ≥90 mmHg Affects 32% of US adult population Heart must work harder to eject blood Places greater strain on arteries Causes enlarged heart, scarred/stiff arteries Eventually leads to atherosclerosis, MI, etc.

Forms of Cardiovascular Disease: Hypertension
Prehypertension Systolic 120 to 139 mmHg Diastolic 80 to 89 mmHg Affects 28% of US adult population More common in black Americans 1.8 times greater rate of fatal stroke 1.5 times greater rate of heart disease death 4.2 times greater rate of kidney disease

Table 21.2

Forms of Cardiovascular Disease: Stroke
Affects cerebral arteries Restricts brain blood flow 795,000 strokes in United States annually Ischemic stroke Most common type Obstructed cerebral artery limits O2 delivery Cerebral thrombosis Cerebral embolism

Hemorrhagic stroke Intracerebral hemorrhage Subarachnoid hemorrhage Vessel in or on brain ruptures Arises from aneurysms (secondary to hypertension or atherosclerotic damage) Rupture  ischemia and pressure on brain tissue  death of brain tissue

Effect of stroke depends on region affected Paralysis on one side most common Each side of brain controls opposite side of body Strokes in right brain Vision problems, memory loss Quick, inquisitive behavior Strokes in left brain Speech/language problems, memory loss Slow, cautious behavior

Forms of Cardiovascular Disease: Heart Failure
Chronic, progressive weakening of the heart Too weak to maintain cardiac output Results from damage to and overworking of heart Hypertension major contributor (75% of cases) Other causes: atherosclerosis, valve diseases, viral infection, MI Causes edema, pulmonary edema Ultimately requires heart transplant

Forms of Cardiovascular Disease: Other Cardiovascular Diseases
Peripheral vascular diseases Arteriosclerosis (obliterans) Varicose veins, phlebitis Valvular diseases Often from viral infections Rheumatic heart disease Congenital heart disease Congenital defects Can affect aorta, valve, or septum

Understanding the Disease Process: Coronary Heart Disease
Pathology of CHD affects vessel wall Tunica intima: endothelium Tunica media: smooth muscle cells, elastin Tunica adventitia: collagen Early theory: initial injury to endothelium Platelets, monocytes adhere to injury (PDGF) Smooth muscle cells and lipids migrate to intima Collection of debris in intima  plaque

Figure 21.4

Figure 21.5

Recent theory: monocytes attach between endothelial cells Become macrophages Ingest oxidized LDL-C Become large foam cells, form fatty streaks Endothelial cells slough off Expose underlying connective tissue Allows platelets to attach Endothelial injury not always precipitating event

Endothelial injury or disruption comes from High blood LDL Free radicals from cigarette smoke Hypertension High plasma homocysteine Infectious microorganisms Atherosclerosis now considered to be inflammatory disease

Plaque consists of Smooth muscle, inflammatory cells, lipids Fibrous cap (thick or thin) Thin caps = more unstable = easier rupture Rupture  thrombus formation Rupture and thrombus account for 70% of MIs Plaques are dynamic (erode, repair, grow)

Figure 21.6

Understanding the Disease Process: Hypertension
Poorly understood condition 90 to 95% of cases idiopathic Remaining 5 to 10% secondary to other issues Kidney disease Adrenal tumors Congenital defect of aorta

Determining Individual Risk
Epidemiology of CHD and hypertension reveals relationships among disease factors Large-scale public studies, often longitudinal Framingham Heart Study Epidemiology does not define causal mechanisms of cardiovascular disease Epidemiology does provide researchers with valuable insights into disease risk factors

Determining Individual Risk: Coronary Heart Disease
Uncontrollable CHD risk factors Heredity, family history Race Sex (male > female) Age Must try to mitigate risk via controllable CHD risk factors instead

Controllable CHD primary risk factors Tobacco smoke Hypertension Abnormal blood lipid profile Physical inactivity Obesity, overweight Diabetes, insulin resistance As number of risk factors , risk of CHD 

Other putative CHD risk factors C-reactive protein (CRP) Fibrinogen Homocysteine Lipoprotein(a) Inflammatory processes and markers may be involved in risk

Table 21.3

Blood triglycerides Blood cholesterol Lipoproteins VLDL cholesterol (risk factor) LDL cholesterol (risk factor) HDL cholesterol (beneficial) Ratio of total cholesterol to HDL (best index)

Determining Individual Risk: Early Detection of CHD Risk Factors
Early detection  preventive treatment In boys 8 to 12, girls 13 to 15 years old 19.8% had total cholesterol >200 mg/dL 5.2% had abnormal resting ECGs 37.5% had 20+ percent body fat High risk in childhood  high risk as adult

Determining Individual Risk: Hypertension
Uncontrollable risks similar to those for CHD Controllable risk factors for hypertension Insulin resistance Obesity, overweight Diet (sodium, alcohol) Tobacco use Oral contraceptives Stress Physical inactivity

Determining Individual Risk: Metabolic Syndrome
Also called insulin resistance syndrome Links CHD, hypertension, abnormal blood lipids, type II diabetes, and abdominal obesity to insulin resistance and hyperinsulinemia Series of correlations and associations Possible causes Obesity and insulin resistance trigger cascade of events Systemic inflammation

Reducing Coronary Heart Disease Risk Through Physical Activity
Epidemiological evidence Risk of MI 2 to 3 times higher in sedentary populations Both occupational and leisure activity Similar results for both men and women CDC findings Physical inactivity equal to other risk factors Sedentary lifestyle 3 times more common than other major risk factors (smoke, hypertension, cholesterol)

How much physical activity  risk of CHD? Physical activity versus physical fitness Physical activity more important than fitness Walking and gardening—examples of low-impact, low-level activity   risk More vigorous exercise may yield greater benefits

Exercise type and intensity related to CHD risk Run 6 mph for 1 h per week  42%  risk Weight train 30 min per week  23%  risk Brisk walk 30 min per day  18%  risk Swimming and cycling unrelated to risk Higher intensity  greater risk reduction

Physical fitness and physical activity may be independent risk factors for CHD Higher fitness and activity both reduce risk Fitness more potent than activity Controversial findings, merit more research

Physiological adaptations to exercise that may reduce risk –  Contractility via LV hypertrophy –  Diameter and capacity of coronary vessels –  Endothelial function and vasodilation –  Vascular inflammation Exercise  enhanced cardiac and vascular function (even with atherogenic diet)

Exercise  reduced risk factors –  Blood pressure (systolic, diastolic) –  LDL, total cholesterol –  HDL cholesterol –  Blood triglycerides –  Total cholesterol relative to HDL Exercise exerts biggest effect on blood lipid profile risk factors

Effect of exercise on other risk factors Weight control Diabetes management Stress reduction Anxiety reduction Note: effects of exercise on blood-related risk factors also reflect exercise effects on plasma volume and body weight

Reducing Hypertension Risk Through Physical Activity
Effect of exercise on hypertension not as well established as effects on CHD Epidemiological evidence – More active people in studies had lower systolic and diastolic pressures Highly fit individuals less prone to hypertension Hypertension associated with low fitness

Physiological adaptations to exercise –  Plasma volume (does not  blood pressure) –  In overall sympathetic nervous activity –  Vasodilation and vascular remodeling Physiological mechanisms that lower blood pressure still poorly understood

Exercise  reduced risk factors –  Body fat –  Blood glucose levels –  Insulin resistance •  BP unrelated to duration of training •  BP may be greater with low or moderate intensity

Risk of Heart Attack and Death During Exercise
Infrequent but highly publicized Risk very, very low Men: 1 death per 1.42 million h of exercise Women: 1 death per 36.5 million h of exercise Habitual exercise   risk of death When death occurs, age affects cause Under 35: more often genetic abnormalities, aneurysm Over 35: more often arrhythmia caused by CHD

Figure 21.8

Risk of Heart Attack and Death During Exercise
CPR outside of hospital increases survival of cardiac arrest by 2 to 3 times Bystanders rarely perform CPR Fear of doing it wrong Fear of legal liability Fear of infection from rescue breathing Chest compressions without breathing  better survival outcomes than traditional CPR

Exercise and Rehabilitating Patients With Heart Disease
Endurance training  changes that reduce work, O2 demand of heart Aerobic exercise helps prevent future complications –  Capillary:muscle fiber ratio –  Plasma volume –  Or maintain O2 supply to heart –  Blood flow to heart –  LV function (continued)

Exercise and Rehabilitating Patients With Heart Disease (continued)
Aerobic exercise helps prevent future complications –  Blood pressure –  Blood lipid values –  Body fat –  Glucose control –  Stress Combining resistance training and aerobic exercise optimal

Exercise Training and Rehabilitating Patients With Heart Disease
Comprehensive program consists of Exercise, physical activity Counseling (nutritional, psychological, sexual) Support forums Exercise rehabilitation improves outcomes 20% lower total mortality and 26% lower risk of death from subsequent MI Rehabilitation patients should have medical evaluation, GXT, exercise prescription

Table 21.4

Cardiovascular Disease and Physical Activity

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