Myocardial Infaction | Anatomy2Medicine
Myocardial Infaction Symptoms

Myocardial Infaction

 

  • Ischemic heart disease (IHD)
  • In most cases, the cause is atherosclerotic narrowing of the coronary arteries
      • It is acutely aggravated by superimposed thrombosis or vasospasm.
    • Metabolic syndrome comprises a group of risk factors including (MCQ)
  • central obesity
  • atherogenic lipid patterns
  • hypertension
      • insulin resistance (sometimes overt diabetes)
  • evidence of a proinflammatory state, such as elevated C-reactive protein.
  • Angina pectoris
      • is episodic chest pain caused by inadequate oxygenation of the myocardium.
      • Stable angina
        • most common form of angina.
        • It is pain that is precipitated by exertion and is relieved by rest or by vasodilators, such as nitroglycerin. (MCQ)
        • It results from severe narrowing of atherosclerotic coronary vessels, which are thus unable to supply sufficient oxygenated blood to support the increased myocardial demands of exertion. (MCQ)
      • Unstable angina  or prolonged or recurrent pain at rest.
  • It is often indicative of imminent myocardial infarction.
        • It is caused by (MCQ)
          • disruption of an atherosclerotic plaque with superimposed thrombosis (most commonly)
          • embolization
          • vasospasm.
      • Prinzmetal angina
        • intermittent chest pain at rest.
        • generally considered to be caused by vasospasm (MCQ)
  • Myocardial infarction
      • Myocardial coagulative necrosis caused by coronary artery occlusion is characteristic. (MCQ)
      • The cells involved in the evolution of a myocardial infarct include neutrophils, macrophages, and fibroblasts.
      • Lymphocytes and plasma cells are not involved
      • There are two distinct patterns of myocardial ischemic necrosis.
        • Transmural infarction
        • Subendocardial infarction
          • limited to the interior one-third of the wall of the left ventricle.
  • Complications
        • Arrhythmia
          • most common cause of death in the first several hours following infarction. (MCQ)
        • Myocardial (pump) failure
          • lead to congestive heart failure and/or shock.
        • Myocardial rupture
          • catastrophic complication that usually occurs within the first 4–7 days (MCQ)
  • may result in death from cardiac tamponade
  • Ruptured papillary muscle
        • Mural thrombosis
          • thrombus formation on the endocardium overlying the infarct
          • lead to left-sided embolism.
  • Ventricular aneurysm
  • Histopathologic Changes in Myocardial infarction (A Very High yield MCQ in Exam)
  • 2–24 hours
        • Slight swelling and change of color
        • Cytoplasm displays increasing affinity for acidophilic dyes
        • striations are lost (MCQ)
        • nuclei disappear
        • neutrophils infiltrate in the lesion
  • By 24 hours
        • Pale or reddish brown infarct with surrounding hyperemia
  • Well-developed changes of coagulative necrosis
        • Progressive infiltration by neutrophils
  • By third day
        • Increasingly yellow color of infarct
  • Replacement of neutrophils by macrophages
        • Phagocytosis of debris begins
      • From 7 days
        • Yellow infarcted area surrounded by congested red border
        • Beginning of growth of young fibroblasts and newly formed vessels into the lesion
        • replacement of neutrophils by macrophages and phagocytosis of debris continues
  • Risk for myocardial rupture greatest within first 4–7 days (MCQ)
    • From 10 days
      • Red, newly formed vascular connective tissue encircles and gradually replaces yellow necrotic tissue (MCQ)
      • Growth of fibrovascular tissue continues
      • replacement of neutrophils by macrophages and phagocytosis of debris are almost complete
  • Between second and fourth week
        • Progressive synthesis of collagen and other intracellular matrix proteins
      • From fifth week
  • Increasing pallor of infarct because of progressive fibrosis
      • Progressive fibrosis
    • Within 3–6 months
      • Well-developed gray- white scar (MCQ)
      • Mature fibrous tissue replaces area of infarction

Enzymes in Myocardial infarction- When do they Rise, Peak and Fall

(A Very High yield MCQ in Exam)