Myocardial infraction

• Define Myocardial infarction (MI)

  Death of heart tissue following a lack of blood supply
• What is the main cause of a myocardial infarction

  Atheromatous plaque rupture with overlying thrombosis.
• Atheroma

  Lipid-rich accumulation in arteries
• Descirbe the development of an atheroma in coronary arteries

  1. Initial damage to endothelium

  2. Cholesterol-rich LDL enters intima

  3. Macrophages become foam cells by taking up the LDL [Fatty streak]

  5. Macrophages release lipid and chemical signals

  6. Cells of intima release collagen

  7. Lipid plaque forms

  8. Fibrolipid cap forms [Atheroma]

  9. Endothelium becomes fragile and ulcerates

  10. Platelets aggregate on plaque and stimulate thrombus formation
• What are the consequences of an atheroma

  • Artery narrowing
  • Thrombus formation on plaque
  • Bleeding into plaque
  • Aneurysm
• Arteriosclerosis

  Thickening and hardening of artery wall
• Atherosclerosis

  Thickening and hardening of high pressure artery wall caused by atheroma
• What are the methods for Acute Myocardial Infarction (AMI) diagnosis

  1. Altered level of cardiac muscle biomarker [e.g. Troponin]

  2. Crushing chest pain [Angina]

  3. ECG changes [Elevated ST region]

  4. Imaging
• What is the issue with ECG interpretation for an MI

  The elevated ST region may take 24 hours to develop and be difficult to interpret
• What are the types of cardiac biomarkers

  
  

  • Enzymes
  • Muscle proteins
• What is thrombosis

  The formation of a blood clot resulting in partial or complete blockage of a blood vessel.
• What are the consequences of the artery narrowing

  Ischaemia. Hypoxia. Angina.
• What is ischeamia

  Reduction in blood flow and therefore oxygen.
• What is hypoxia

  when a tissue is deprived of oxygen.
• What is angina

  Chest pain due to reduced coronary blood flow.
• What is an aneurysm

  Swelling of a blood vessel
• What does thrombus formation cause

  Myocardial infarction
• what does bleeding into a plaque cause

  Myocardial infarction
• What are the enzyme cardiac biomarkers

  Creatine kinase.
• How are creatine kinase cardiac biomarkers formed

  From muscle damage.
• What are the muscle protein cardiac biomarkers

  Troponin I. Troponin T. Myoglobin.
• What is cT

  These are cardiac biomarkers named troponin.
• What is the role of cTC

  Binds calcium to regulate contraction
• What is the role of cTI

  
  

  Inhibits contraction in the abscence of calcium and cTC
• What is the role of cTT

  Binds to tropomyosin
• What are troponins

  They exist as a complex with actin and myosin and regulate striated muscle contraction.
• Why are cT prefered to myoglobin as cardiac biomarker detection molecules

  Myoglobin can be found in skeletal muscle. But cTs are specific to cardiac muscle.
• What is the treatment for an MI

  Thrombolytic agents. Anticoagulants. Coronary angioplasty. Coronary bypass.
• How does a coronary bypass work.

  Graft of an artery or vein added to coronary artery. Enables blood to flow around the obstruction.
• How does a coronary angioplasty work

  Catheter is inflated in the obstructed vessel to remove obstructions.