Atheroma and Infarction

Question 1

What’s an atheroma?

What can atheroma’s lead to?

Answer 1

• Degeneration of arterial wall due to accumulation of fatty deposits and necrotic tissue.
• Atherosclerosis

Question 2

Describe the components of an atheromatous plaque

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Answer 2

• Necrotic core - contains lipids, cholesterol, fibrin, foam cells, cell debris.
• There’s neovascularisation at base of plaque (new blood vessels).
• Cellular layer made of smooth muscle, macrophages, lymphocytes, connective tissue.
• Fibrous cap just underneath endothelium - made of smooth muscle and collagen.

Question 3

What are the common sites for atheroma formation?

What are the main risk factors for an atheroma?

Answer 3

• Circle of Willis, Carotids, Coronary arteries, Aorta, Iliac’s
• Age, Male, Genetics, Smoking, Hyperlipidaemia, HT, Diabetes, Obesity,
  Metabolic syndrome, Alcohol, Drugs

Question 4

Explain the process of the development of an atheroma

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Answer 4

1. Initiation:
   • Oxidised LDL, Ang II, Inflammation activate the endothelium = cytokine and adhesion molecule released.
   • Monocytes then adhere and enter the tunica intima - becomes macrophage.
2. Plaque formation:
   • Over time, smooth muscle cells from tunica media can enter tunica intima - they then divide.
   • A change in the smooth muscle cell’s gene sequences = secretion of collagen and elastin fibres.
   • LDL enters tunica intima and forms a Foam cell with macrophage.

Maturation of Plaque:
• Collagen and elastin fibres migrate to form the Fibrous cap.

Calcification and Instability:
• Calcium deposits in tunica intima and Fibrous cap.

Question 5

What can plaque rupture lead to?

What are the consequences of plaque rupture?

Answer 5

• Thrombosis
• • Occlusive thrombosis in a coronary artery can lead to an MI
  • Thromboembolism in the brain can lead to an Ischaemic stroke
  • Peripheral vascular disease e.g. critical limb ischaemia
  • Aneurysm due to wall weakness

Question 6

What is an Infarction?

What is Angina?

What is the difference between the cause of Stable and Unstable Cardiac Angina?

What causes a Myocardial Infarction?

What are the ECG changes of an MI?

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Answer 6

• Where there’s dead/necrotic tissue due to vessel obstruction
• Chest pain due to restricted coronary blood flow
• • Stable angina is due to a plaque, but no occlusion - permanent flow limitation
  • Unstable angina is due to a plaque that forms a transient thrombosis (doesn’t last long)
• Complete occlusion of a coronary artery
• ST elevation/depression

Question 7

What is given to treat an MI?

What type of surgeries can be carried out to remove the blockage? What does it do to the heart?

What are the pharmacological for an MI and ischaemic stroke?

Why must one be managed after an MI? What can be done?

Answer 7

• Oxygen, anticoagulants, analgesics etc.
• Ballon angioplasty, Stent, CABG - re-perfuses the heart
• tPA given, which converts Plasminogen → Plasmin = Fibrinolysis - breaks down the clot.
• To reduce the risk of recurrence - stop smoking, control BP, exercise.