Atherosclerosis, Coronary Artery Disease

Where in the arteries does atherosclerosis occur? What is it?

Atherosclerosis is a disease that occurs in the tunica intima of arteries

• Consists of fibrous fatty lesions that form in medium / large arteries

What does atherosclerosis result in?

Atherosclerosis results in:

• Increased wall thickness → decreased elasticity

• Reduced vessel radius → reduced flow rate

• Ischemia

What is atherosclerosis’ Etiology?

Atherosclerosis etiology is due to endothelial cell damage

Describe the Cellular Phase of Atherosclerosis

1. Endothelial permeability increases, allowing monocytes and leukocytes to move from the bloodstream into the inner arterial wall

2. Monocytes differentiate into macrophages and ingest lipid, transforming into lipid filled foam cells

3. Macrophages release growth factors and ROS, leading to the proliferation of smooth muscle

4. All of this leads to progressive tissue damage and growth of the plaque lesion

Describe the steps of plaque formation in atherosclerosis

1. Cholesterol is deposited beneath the endothelium

2. The deposits are invaded by fibrous tissue

3. Deposits become calcified as a result into atherosclerotic plaques

4. These plaques protrude into vessel lumens, which blocks blood flow

5. As plaque builds up, the gradual hardening and narrowing of the coronary arteries can lead to angina pectoris and a myocardial infarction

What are low density lipoproteins (LDLs)?

Low density lipoproteins are particles made of fat and protein that carries cholesterol in your blood

What usually happens to LDLs in the blood?

LDLs are usually either oxidized by ROS or recognized as foreign and ingested by macrophages

What is coronary artery disease?

Coronary artery disease is the atherosclerosis of the coronary arteries

What disease does Coronary artery disease cause?

Coronary artery disease causes ischemic heart disease

In CAD, which region of heart muscle is damaged first? Why?

In CAD, the subendocardial regions of heart muscle are damaged first because they have a difficult time getting adequate blood flow

Which areas of the heart does the right coronary artery supply?

The right coronary artery supplies the right ventricle and posterior regions of the heart

Which areas of the heart does the left coronary artery supply?

The left coronary artery supplies the left ventricle and interventricular septum

What is Diastole and Systole?

Diastole: Ventricles relax

• DR

Systole: Ventricles contract

• SC

What are the two controls of Myocardial blood flow?

1. Autonomic control

2. Local autoregulatory control

In autoregulatory control, what controls myocardial blood flow?

Local metabolism controls myocardial blood flow in autoregulatory control

What two chemicals are present during autoregulation?

Nitric oxide & Adenosine

Is myocardial blood flow highest during systole or diastole? Why?

Diastole, because during systole the muscle compresses the coronary arteries

What is collateral circulation?

Collateral circulation is the network of backup blood vessels that reroute the blood if an artery or vein is blocked

What are anastomoses? What is their purpose?

Anastomoses are the connections that exist between smaller coronary arteries, with the purpose of providing an alternative path of blood flow