MYOCARDIAL INFARCTION

MYOCARDIAL INFARCTION

1. Also known as

   • Heart Attack

2. Definition

   • Necrosis of heart muscle
     • due to
       • abrupt decrease in coronary blood flow following a complete thrombotic occlusion of a coronary artery previously narrowed atherosclerosis

3. Risk factors

   • Hypertension
     • Smoking
       • Diabetes Mellitus
         • Stress
           • Hypercholesterolemia
             • Obesity
               • Age
                 • M >45 , F >55
                 • Family history of MI
                   • First concern
                     • first and second degree relatives
                   • presence of CAC upon test implementation

4. Investigations

   • ECG
     • Cardiac biomarkers
       • protien molecules released into the blood stream from damged heart muscle
       • These biomarkers have a characteristic rise and fall pattern.
         • these include
           • Myoglobin
             • Ck isoforms
             • Troponin
     • but since it can be inconclusive, biomarkers are frequently used to evaluate for myocardial injury
   • Angiography
     • Process of taking an x-ray of the blood vessels to see which vessels obstructed and requires repairing, injection of radio-opaque material

5. Complications

   • APPEAR
     • A
       • Arrhythmia (atrial or ventricular fibrillation, cardiac block)
       • P
         • Pump failure
         • P
           • Pericarditis
           • E
             • A
               • R
                 • Rupture (free wall of the ventricle, septum, or papillary muscle)
               • Aneurysm of the ventricle
             • Emboli

6. Pathogenesis

7. Management

   • Cardiac Depressent drugs
     • Beta-blockers
   • Vasodilators
     • Nitrodilators, Angiotensin converting enzymes inhibitors, Angiotensin receptor blockers
   • Antiarrhythmics
   • Anti-thrombotics
     • anticoagulant (warfarin), anti- platelet drugs (aspirn)
     • Thrombolytics
       • plasminogen activators
       • Analgesics (reduce pain)
         • morphine

8. Microscopic morphology

   • 1-3 days
     • 3-7 days
       • 1-2weeks
         • by the end of 6 weeks
           • Organization & scar
         • Granulation tissue
       • Demolition/Resorption of necrotic debric
     • Coagulation necrosis and inflammation

9. is a form of

   • Coagulative necrosis
     • Types of necrosis
       • Liquefactive necrosis
         • Caseous necrosis
           • Fat necrosis
             • Gangrenous necrosis
               • Fibrinoid necrosis

10. seen in

    • Unstable Angina Pectoris
      • Definition
        • Progressive, increasing frequency, precipitated with progressively less effort and even at rest & of prolonged duration (plaque rupture with mural thrombosis/ thromboembolism or vasospasm or both.
    • Acute coronary syndrome
      • common pathogenesis
        • Coronary artery occlusion due to atheromatus Plaques form in coronary arteries, when increased to critical levels fissuring leads to plaque distruptionin the coronary arteries, therefore superimposed thrombosis results.
    • Sudden Cardiac Death
      • Definition
        • Unexpected death from cardiac causes early after or without onset of symptoms. Mostly it is a complication and often first clinical manifestation og IHD (mechnism of death is almost always a lethal arrythmia.

11. May present as

    • referred pain

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