Cardiovascular Disease and Physical Activity. CHAPTER 21 Overview Forms of cardiovascular disease...

Cardiovascular Disease and Physical

Activity

CHAPTER 21 CHAPTER 21 OverviewOverview

• 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 Introduction to Cardiovascular DiseaseCardiovascular 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 21.1Figure 21.1

Introduction to Introduction to Cardiovascular DiseaseCardiovascular 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 21.1Table 21.1

Forms of Cardiovascular DiseaseForms of Cardiovascular Disease

• Coronary heart disease (CHD)

• Hypertension

• Stroke

• Heart failure

• Other (peripheral, valvular, congenital)

Forms of Cardiovascular Disease:Forms of Cardiovascular Disease:Coronary Heart DiseaseCoronary 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

Forms of Cardiovascular Disease:Forms of Cardiovascular Disease: Coronary Heart 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:Forms of Cardiovascular Disease:HypertensionHypertension

• 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:Forms of Cardiovascular Disease:HypertensionHypertension

• 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

Forms of Cardiovascular Disease:Forms of Cardiovascular Disease:StrokeStroke

• 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:Forms of Cardiovascular Disease:Heart FailureHeart 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:Forms of Cardiovascular Disease:Other Cardiovascular DiseasesOther 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:Understanding the Disease Process:Coronary Heart DiseaseCoronary 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

Understanding the Disease Process:Understanding the Disease Process: Coronary Heart Disease Coronary Heart Disease

• 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

Understanding the Disease Process:Understanding the Disease Process: Coronary Heart Disease Coronary Heart Disease

• 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

Understanding the Disease Process:Understanding the Disease Process:Coronary Heart DiseaseCoronary Heart 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)

Understanding the Disease Process:Understanding the Disease Process:HypertensionHypertension

• 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 RiskDetermining 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:Determining Individual Risk: Coronary Heart Disease 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


• 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: Determining Individual Risk: Early Detection of CHD Risk FactorsEarly 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:Determining Individual Risk:HypertensionHypertension

• 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:Determining Individual Risk:Metabolic SyndromeMetabolic Syndrome

• 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 Reducing Coronary Heart Disease Risk Through Physical ActivityRisk 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 Reducing Hypertension Risk Through Physical ActivityThrough 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 Risk of Heart Attack and Death During ExerciseDuring 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

Risk of Heart Attack and Death Risk of Heart Attack and Death During ExerciseDuring 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 Exercise and Rehabilitating Patients With Heart DiseaseWith 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 Exercise and Rehabilitating Patients With Heart Disease With Heart Disease (continued)(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 Exercise Training and Rehabilitating Patients With Heart DiseasePatients 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

Cardiovascular Disease and Physical Activity. CHAPTER 21 Overview Forms of cardiovascular disease...

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