Ischemic Heart Disease

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IHD Basics - Heart's SOS Call

  • Definition: Myocardial O₂ supply/demand mismatch → ischemia.
  • Etiology: >90% due to coronary atherosclerosis (CAD).
  • Epidemiology: Top global killer; high in India.
  • Pathogenesis: Atheroma → progressive stenosis / acute plaque disruption → thrombosis → ↓coronary flow → ischemia.
  • Risk Factors (Major):
    • Non-Modifiable: Advancing age, male gender, family history (1st degree, M<55y, F<65y).
    • Modifiable: Cigarette smoking, Hypertension (BP ≥140/90 mmHg), Diabetes Mellitus, Dyslipidemia (↑LDL, ↓HDL), Obesity (BMI ≥30), Physical inactivity.

⭐ Symptomatic ischemia (e.g., stable angina) often with >70-75% coronary stenosis.

Atherosclerosis - Plaque Attack

Chronic inflammation from endothelial injury.

  • Pathogenesis:
  • Plaque Components:
    • Fibrous cap: SMCs, collagen.
    • Necrotic core: Lipids, cholesterol crystals, foam cells.
    • Shoulder: Inflammatory cells; rupture site.
  • Plaque Types:
    • Stable: Thick cap, small core, ↓inflammation → stenosis.
    • Vulnerable: Thin cap, large core, ↑inflammation (MMPs) → rupture.

      ⭐ Most common sites: Abdominal aorta > Coronaries > Popliteal > Carotids > Circle of Willis. (📌 A CoPoCaCi) Atherosclerotic plaque progression and types

IHD Syndromes - Clinical Crisis

  • Angina Pectoris: Chest pain due to transient myocardial ischemia.
    • Stable Angina: Predictable, on exertion; relieved by rest/nitrates.
    • Unstable Angina: Crescendo, at rest, or new-onset severe; high risk of MI.
    • Prinzmetal (Variant) Angina: Coronary artery spasm; occurs at rest, often at night; ST elevation during pain.
  • Myocardial Infarction (MI): Myocardial necrosis due to prolonged ischemia.
  • Chronic IHD: Progressive heart failure due to ischemic myocardial damage.
  • Sudden Cardiac Death (SCD): Unexpected death from cardiac causes, often due to lethal arrhythmia (e.g., VFib) in IHD.
FeatureStable AnginaUnstable AnginaPrinzmetal Angina
PrecipitantExertion, stressCan occur at restRest, often cyclical
PlaqueFixed stenosisDisrupted plaque, thrombusCoronary spasm
ECG (during pain)ST depression (usually)ST depression / T wave inversionST elevation
BiomarkersNormalNormalNormal

MI Deep Dive - Infarct Insights

  • Pathophysiology: Coronary occlusion → necrosis. Irreversible injury: 20-40 mins. Wavefront: subendocardium → epicardium.
  • Morphological Changes:
    TimeGrossMicroscopic
    0-4hNone/Mottling (late)Wavy fibers, edema, early coag. necrosis
    4-24hDark MottlingCoagulative necrosis, neutrophils
    1-7dYellow-tan centerNeutrophils (peak), Macrophages, phagocytosis
    1-2wMax yellow, softGranulation tissue (capillaries, fibroblasts)
    2-8wGray-white scarIncreasing collagen, ↓cells
    >2mDense fibrous scarDense collagen
  • Complications: Arrhythmias (early death), LV failure/shock, mural thrombus (emboli), ventricular aneurysm, rupture (free wall, septum, papillary), pericarditis (fibrinous; Dressler's).
  • Markers: Troponin I/T (specific; ↑2-4h, peak 24-48h). CK-MB (↑3-6h, peak 12-24h; reinfarction). Myocardial Infarction Pathophysiology

⭐ Ventricular free wall rupture typically occurs 3-7 days post-MI, coinciding with peak macrophage lysis.

High‑Yield Points - ⚡ Biggest Takeaways

  • Atherosclerosis of coronary arteries is the primary cause of IHD.
  • Stable angina: Fixed stenosis (>70%), exertional pain. Unstable angina: Plaque rupture, rest pain.
  • MI: Coagulative necrosis. Troponins (most sensitive/specific). CK-MB for reinfarction.
  • MI morphology: Coagulative necrosis visible 4-12 hrs; neutrophils 1-3 days; granulation tissue 1-2 wks.
  • Most common MI complications: Arrhythmias (early), Dressler's syndrome (late pericarditis).
  • Sudden Cardiac Death (SCD): Often due to IHD-induced lethal ventricular arrhythmias.

Practice Questions: Ischemic Heart Disease

Test your understanding with these related questions

A 45-year-old man presents with intermittent pain in the chest, radiating to the left arm, aggravated by exertion, and relieved by rest. What is the most appropriate initial investigation?

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Flashcards: Ischemic Heart Disease

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_____ is a cardiac tumor associated with tuberous sclerosis

TAP TO REVEAL ANSWER

_____ is a cardiac tumor associated with tuberous sclerosis

Rhabdomyoma

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