Atherosclerosis & Cardiovascular Disease

• Atherosclerosis is a multifactorial inflammatory disease of the arteries characterized by the deposition of plaques of fatty material on their inner walls

Objectives

• Outline the steps leading to atherosclerosis and describe how each risk factor contributes to cardiovascular disease (CVD)
• Advocate for exercise as preventative medicine for each modifiable risk factor for CVD
• Apply the cutoff scores for each risk factor to physical therapy practice to determine precautions for exercise

CVD Traditional Risk Factors

• Non-modifiable risk factors: Age, sex, family history, and race
• Modifiable risk factors: Smoking, obesity, nutrition, inactivity, diabetes, cholesterol, triglycerides, and stress

Thresholds for non-modifiable risk factors

• Sex: More prevalent in males than females
• Age: Men ≥ 45 years, Women ≥ 55 years
• Family History: First-degree relative with MI, coronary revascularization, or sudden cardiac death; Men > 55 years, Women > 65 years
• Race: More prevalent in African-Americans & Hispanic-Americans than Caucasians

Thresholds for modifiable risk factors

• Hypertension: 130/80 mmHg or on BP-lowering meds
• Dyslipidemia: Abnormal blood lipids or on LDL-lowering meds
• ≥ 130 mg/dl LDLc
• < 40 mg/dl HDLc men <50mg/dl HDLc women. HDLc is the good cholesterol

• 150 mg/dl Triglycerides

• Obesity: BMI ≥ 30
• Waist girth for men >102 cm, women > 88 cm
• Insulin resistance: ≥ 100 mg/dl fasting blood glucose (126 is diabetes, pre-diabetes is 100)
• Smoking: Current smoker, quit smoking < 6 months ago, or exposure to environmental tobacco smoke
• Physical Inactivity: < 30 min of moderate-intensity exercise on < 3 days per week for <3 months

Risks of Atherosclerosis

• Coronary Artery Disease (CAD)
• Myocardial Infarction (MI)
• Cerebral Artery Disease
• Stroke (CVA) – Clogged arteries to the brain
• Peripheral Arterial Disease (PAD)
• Burgers Test
• Valve disease
• Cardiomyopathy
• Heart failure

Coronary Artery Disease (CAD)

• The heart is highly oxidative.
• Oxygen consumption must meet demand because oxygen is not stored.
• mVO2 = estimate of myocardial oxygen demand or work.
• Rate Pressure Product: mVO2 = HR x SBP

Steps in the development of atherosclerosis

• LDL enters through the endothelium.

• LDL becomes oxidized.

• Monocytes attach to the endothelium.

• Monocytes go in between endothelial cells and become macrophages; Macrophages eat oxidized LDL, forming foam cells.

• Smooth muscle cells migrate to the intima.

• A fibrous cap forms.

• The plaque can rupture, leading to a thrombus.

• Curves and bifurcations in arteries result in turbulent flow, increasing atherosclerosis

Thrombosis vs Embolism

• Thrombosis is local coagulation or clotting of the blood in a vessel
• Embolism is the obstruction of a blood vessel by a blood clot or foreign substance

Exercise and CVD Risk Factors

• Atherosclerosis risk factors can be mitigated with exercise

AGING: Men ≥ 45 & Women ≥ 55 yrs

• CVD: Decrease in NO bioavailability (greater oxidative stress), increase in arterial stiffness, increased circulating catecholamines, and increase oxidative stress
• EXERCISE: Raises HDL; lowers triglycerides, less resting SNS activity, increases NO bioavailability, and decreases arterial stiffness

HYPERTENSION: ≥130/80

• CVD: High pressure directly damages the endothelium, increases arterial stiffness, and is associated with greater oxidative stress EXERCISE: Increases NO bioavailablity and decreases arterial stiffness

ABDOMINAL OBESITY: BMI ≥ 30 kg/m² OR Waist >102 cm (Men); > 88 cm (Women)

• CVD: Comorbidities of HTN, DM, dyslipidemia, increased pro-inflammatory cytokines, increased cytokines: TNF-a associated with arterial stiffness, increased fat mass increases TPR, fat deposition in myocardium and around kidneys impairs function
• EXERCISE: Aerobic exercise greatly decreases abdominal fat, exercisers seem to have less inflammatory cytokines, and lower resting SNS

DYSLIPIDEMIA: total cholesterol ≥ 200; LDL ≥130; HDL ≤ 40 mg/dl; triglycerides <150

• CVD: High plasma LDL increases accumulation in arterial walls and low HDL decreases cholesterol transport out of the arterial wall and eliminates anti-inflammatory and anti-oxidant effects of HDL
• EXERCISE: Exercise can increase HDL levels and lowers triglycerides

Medication: Statins

• Statins (HMG-CoA reductase inhibitors) work in the liver to block an enzyme (HMG-CoA) that helps the body make cholesterol
• Statins also lower inflammation in the arteries and stabilize plaque
• Muscle pain is the most common side effect

INSULIN RESISTANCE/PRE-DIABETES:100-125 mg/dl

• CVD: Decreases NO production, hyperglycemia increases blood viscosity, AGEs endothelial damage; increased arterial stiffness; Hyperinsulinemia increases proliferation of VSMCs
• EXERCISE: Decreases viscosity, increases insulin sensitivity/responsiveness, increases GLUT 4 transporters, more muscle mass to increase glucose storage, less insulin necessary for glucose uptake, and increases anti-oxidant defenses

SMOKING

• CVD: Increases free-radical production oxidative stress decreases NO production, increases SNS vasoconstriction, increases LDL & TGs and decreases HDL, increases pro-inflammatory cytokines, increases blood viscosity increases resistance to flow, and increases the coagulability of the blood promoting thrombosis
• EXERCISE: Typically reduces the number of cigarettes smoked per day, can increase NO availability, reduces blood viscosity, and reduces coagulability of the blood.

Explore atherosclerosis, a multifactorial inflammatory artery disease. Learn its risk factors, like age, sex, smoking, and obesity. Discover exercise's preventative role and apply risk factor cutoffs in physical therapy.