Chapter 15&16

Protective Cap Formation

• When plaque forms, the body tries to help by sending muscle cells from the surrounding area to form a protective cap over the debris.

• This cap contains connective tissues like collagen and elastin to keep it in place.

Plaque Growth and Cap Vulnerability

• As plaque grows larger, the protective cap forms around it.

• If the cap is thin, the plaque becomes vulnerable to rupture due to the high pressure of blood flow in the arteries.

Consequences of Plaque Rupture

• If the cap ruptures, the necrotic area of the plaque is exposed, leading to an inflammatory response.

• Platelet-derived growth factor is released, causing blood clots to form.

• A clot can block the artery radius, preventing blood flow to the target tissue.

Impact on Target Tissues

• The target tissue (e.g., heart, brain, legs) relies on oxygen and nutrients from the blood vessel.

• If a plaque ruptures and a clot forms, the target tissue may die due to lack of blood flow.

• If the target is the heart, it leads to myocardial infarction (heart attack), resulting in dead proteins in the myocardium.

• If it occurs in the brain, it leads to a stroke by blocking blood flow to that area.

Stable vs. Unstable Angina

• A thick cap is desirable for plaque stability.

• Stable angina indicates a stable plaque that is not rupturing.

• Unstable angina or myocardial infarction usually results from a ruptured plaque, possibly due to a thin cap.

Factors Contributing to Rupture

• Plaque rupture can occur in high-pressure areas like the coronary arteries.

• A vulnerable plaque may get ripped, exposing the necrotic center and leading to clot formation.

Role of Aspirin

• People with heart disease may be prescribed a baby aspirin regimen as a blood thinner to reduce platelet activity.

• Reducing platelet activity can minimize the size of potential clots if the plaque ruptures.

• Even if a clot forms, some blood flow may still reach the target area if the clot is small, preventing complete tissue death (hypoxia).

Aneurysm Formation

• If a vessel wall becomes weak, it may form an aneurysm, which is a bubble under the wall.

• Blood can collect in the weakened area, potentially leading to rupture.

• There is a risk of thrombus forming if the aneurysm ruptures.

Atherosclerosis Domino Effect

• Injury to the endothelium initiates a series of events leading to atherosclerosis and potential complications.

Hypertension

• First need to identify what is causing the hypertension.

• If no cause is identified, then it is deemed idiopathic and lifestyle modifications are necessary.

• Medications are not immediately required.