Coronary Artery Disease Overview

Coronary Artery Disease

• A narrowing or blockage of coronary arteries, usually due to plaque buildup
• Coronary arteries supply oxygen-rich blood to the heart
• Plaque buildup limits how much blood can reach the heart

Coronary Atherosclerosis

• Buildup of fats, cholesterol, and other substances on artery walls
• This buildup is called plaque
• Plaque can cause arteries to narrow, blocking blood flow
• Plaque can lead to a blood clot

Causes

• Exact cause is unknown
• May start with damage or injury to the inner layer of an artery
• Damage may be caused by:
  • High triglycerides
  • High blood pressure
  • Smoking
  • Insulin resistance
  • High cholesterol
  • Diabetes
  • Obesity
  • Inflammation from an unknown cause or from diseases such as arthritis

Pathophysiology

• Low-density lipoprotein molecules (LDL) become oxidized by oxygen free
• When oxidized LDL comes in contact with an artery wall, a series of reactions occur to repair the damage caused by oxidized LDL
• The body's immune system responds by sending specialized white blood cells (macrophages and T-lymphocytes) to absorb the oxidized-LDL, forming specialized foam cells
• These white blood cells are not able to process the oxidized-LDL, and ultimately grow then rupture
• Eventually, the artery becomes inflamed
• The cholesterol plaque causes the muscle cells to enlarge and form a hard cover over the affected area
• This hard cover causes a narrowing of the artery, reduces the blood flow and increases blood pressure

Lipid Profile

• Lipoproteins are referred to as low-density lipoproteins (LDL) and high-density lipoproteins (HDL)
• LDL (normal level, less than 130 mg/dL) are the primary transporters of cholesterol and triglycerides into the cell
• HDL (normal range in men, 35 to 65 mg/dL; in women, 35 to 85 mg/dL) have a protective action. They transport cholesterol away from the tissue and cells of the arterial wall to the liver for excretion
• Cholesterol (normal level, less than 200 mg/dL, High: = 240 mg/dL)
• Triglycerides (normal range, 40 to 150 mg/dL) composed of free fatty acids and glycerol, are stored in the tissue and are a source of energy

Stages of Atherosclerosis

Normal Heart and Artery vs.Artery with Plaque Buildup

• Red blood cells
• Coronary artery
• Heart | * Artery wall
• Red blood cells
• Plaque
• Narrowed coronary artery
• Heart
• Fat |

Physiologic Factors that Increase Risk

Modifiable

• Having diabetes
• Tobacco smoking, increases risk by 200% after several pack years
• Having high blood pressure
• Elevated serum C-reactive protein concentrations

Nonmodifiable

• Advanced age
• Male sex
• Having close relatives who have had some complication of atherosclerosis (e.g., coronary heart disease or stroke)
• Genetic abnormalities, e.g.familial hypercholesterolemia

Lesser or Uncertain

• Being obese (in particular central obesity (also referred to as abdominal obesity))
• A sedentary lifestyle
• High carbohydrate intake
• Elevated serum levels of triglycerides
• Stress

Signs and Symptoms

• Depend on the degree of narrowing of the arterial lumen, thrombus formation and obstruction of blood flow
• Inadequate supply of blood that leads to deprives in oxygen in muscle (ischemia)
• Angina pectoris, chest pain that is brought about by myocardial ischemia
• If blood supply decreases is great and longer, myocardial infarction produce
• Damaged myocardium replaced by scar tissue causing various degrees of myocardium dysfunction
• Inadequate cardiac output and heart failure occur

Treatment

• Non-pharmacological means are usually the first method of treatment, such as cessation of smoking and regular exercise
• If these methods do not work, medicines are usually the next step
  • Statins: block cholesterol synthesis, lower low density lipoprotein (LDL) and triglyceride levels and increase high density lipoprotein (HDL)
  • Nicotinic acids: lower LDL and increase HDL
  • Fibrates: Reduce triglycerides, lowers LDL, and elevate HDL
  • Bile Acid Sequestrants: binds to bile acids in the intestine and prevents their reabsorption
  • Ezetimibe: inhibit the absorption of cholesterol from the small intestine

This quiz covers important aspects of coronary artery disease, including its causes, effects of atherosclerosis, and underlying pathophysiology. Learn how plaque buildup can lead to serious health issues by impacting blood flow to the heart.