Myocardial Infarction:

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Myocardial Infarction

• Dr. Venkatesh M. Shashidhar
• Senior Lecturer in Pathology
• Fiji School of Medicine.

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Anatomy
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Coronary Arteries
LCx LAD

• Left Coronary A.
• L.A.Descending
• Left Circumflex
• Right Coronary A.

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Ischaemic Heart Disease

• Etiology Atherosclerosis most common.
• Ischemia / Infarction.
• Angina stable/unstable.
• Risk factors
• Hypertension, Diabetes Smoking,
• Life style, Diet, Hypercholesterolemia
• Male Sex, Age, Genetic.

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Patterns of CHD

• Angina Pectoris
• Acute Myocardial Infarction
• Sudden cardiac death

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Pathogenesis

• Obstruction to blood flow.
• Atheroma, Thrombosis Embolism
• Diminished coronary perfusion.
• Ischemia Angina
• Infarction Necrosis
• Inflammation
• Granulation tissue
• Fibrous scarring.

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Gross - Morphology - Micro

• 0-18h none
• 24-48h Pale, edema
• 3-4D Hemorrhage
• 1-3W Thin, yellow
• 3-6W Tough white

• None
• Edema, Acute inflammation
• Necrosis, granulation
• Granulation ? fibrosis
• Dense Fibrosis

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Coronary Atherosclerosis
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Myocardial Infarction - Gross
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Coronary Atherosclerosis with Thrombosis
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Myocardial Infarction 1 wks.
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Myocardial Infarction - CS
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2wk - Myocardial Infarction - 3d
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Normal Myocardium
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MI 18-24 hr loss of nucleus, contaction bands,
coagulative necrosis.
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MI 3-4 day Hemorrhage, inflammation.
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MI 1-2w Granulation tissue
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MI 2-4 W - Resorption, fibrosis
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MI gt4-6 W - Collagen Scar
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Complications

• Arrhythmias and conduction defects,
• Extension of infarction, or re-infarction
• Congestive heart failure (pul edema)
• Cardiogenic shock
• Pericarditis
• Mural thrombosis, - embolization
• Myocardial wall rupture, tamponade
• Papillary muscle rupture, Ventricular aneurysm

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MI - Rupture
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Laboratory Diagnosis

• Creatinine Kinase
• CK- Isoenzymes (Fractions)
• MM - Muscles cardiac Skeletal
• MB - exclusively in cardiac muscle.
• BB - Brain, Bowel Bladder
• Troponins - I T.
• LDH - 1-5 (1 - 2 flip)
• Myoglobin