Myocardial infaction

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  • 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

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Heart Attack / Myocardial Infarction [HD Animation]
Khan Academy – Pathophysiology of Acute Myocardial Infarction (Heart Attack)
A look at what happens to you and your heart during a heart attack
Acute Myocardial Infarction – Heart Attack
Myocardial Infarction and Coronary Angioplasty Treatment, Animation.
Myocardial infarction, commonly referred to as heart attack, is the sudden death of part of the heart muscle due to loss of blood flow. This occurs when one of the coronary arteries — the arteries that supply blood to the heart — is blocked. The blockage is commonly due to atherosclerosis – cholesterol plaques/fat deposits on the wall of blood vessels.
Surgical repair of post myocardial infarction VSD with coronary bypass surgery
Cardiovascular Medicine-Myocardial Infarction-Understanding Disease Series
Cardiovascular Medicine-Myocardial Infarction-Understanding Disease Series
Myocardial Infarction- Animation
This animation video gives an exact idea how MI occurs!!