Eschemic Heart Disease

Overview

• Biggest killer: Leading cause of death worldwide.
• In the US, >30% of Americans over 35 die from it.

Definition

• Eschemia: More than just reduced oxygen (hypoxia), includes reduced nutrient delivery and waste removal due to decreased blood flow.
• Heart Disease: Refers to problems originating from the heart.

Coronary Arteries

• Blood vessels supplying the heart:
  • Left coronary artery: Branches into the left circumflex (LCX) and left anterior descending (LAD).
  • Right coronary artery: Travels to the right side and includes branches like the posterior descending artery (PDA).

Anatomy and Function

• Epicardium: Outer layer where most coronary arteries reside.
• Myocardium: Heart muscle.
• Endocardium: Inner layer lining the heart chambers.
• Blood vessel images: showing how they feed different heart areas.
  • LAD: Feeds 2/3 of interventricular septum and anterior wall of the left ventricle.
  • LCX: Feeds lateral wall of the left ventricle.
  • Right coronary artery (RCA): Feeds all of the right ventricular wall and posterior part of the septum.
  • PDA: Part of RCA, feeds the posterior inferior wall.

Pathophysiology

Atherosclerosis

• Main cause: Over 90% of cases.
• Two types:
  • Stable Plaque: Chest pain (angina) during exercise or stress, resolves with rest or vasodilators.
  • Unstable Plaque: Can rupture leading to thrombus and acute coronary syndrome (ACS).

Acute Coronary Syndrome (ACS)

• Unstable Angina: Chest pain occurring without exercise; doesn't always resolve with rest or medication.
• Myocardial Infarction (MI): Cell death detected by blood biomarkers like troponin.

Other Causes

1. Vasospasm:
   • Short-term (transient) causes Prinzmetal angina.
   • Long-term causes MI.
2. Microvascular Dysfunction:
   • Minor contributes to ACS.
   • Severe leads to broken heart syndrome (Takotsubo cardiomyopathy).

Types of MI

• NSTEMI (Non-ST Elevated MI): Sub-endocardial infarction, shows ST depression on ECG.
• STEMI (ST Elevated MI): Transmural infarction, shows ST elevation on ECG.

ECG Interpretation

• ECG basics: P, QRS, T waves relate to heart's electrical activity.
• Lead Analysis: Different leads show different parts of heart.
  • V1-V4: Anterior/septal (LAD).
  • V5, V6, AVL, Lead 1: Lateral (LCX).
  • Lead 3, AVF, Lead 2: Inferior (RCA, PDA).
• ST Elevation/Depression:
  • STEMI: Elevated ST segment in transmural infarction.
  • NSTEMI: Depressed ST segment in subendocardial infarction due to early depolarization.

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--- Dr. Mike Todorovich