Myocardial ischemia: causes, manifestations, consequences
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Myocardial ischemia[edit | edit source]
Insufficient blood flow (and thus oxygen supply) to the myocardium due to an imbalance between oxygen supply and oxygen demand.
Pathophysiology[edit | edit source]
- Most commonly due to atherosclerosis → narrowing of coronary arteries
- Leads to anaerobic metabolism, lactate buildup, impaired contractility
- If prolonged → myocyte injury, necrosis → myocardial infarction
Etiology[edit | edit source]
- Decreased oxygen supply:
- Atherosclerotic plaque
- Coronary thrombosis (acute coronary syndrome)
- Coronary vasospasm
- Severe hypotension/shock
- Severe anemia
- Increased oxygen demand
- Tachycardia
- Hypertension (↑ afterload)
- Fever
- Hyperthyroidism
- Physical exertion or emotional stress
Manifestations[edit | edit source]
- Chest pain (pressure, squeezing, tightness) → angina pectoris w/ possible radiation to left arm, neck, jaw
- Dyspnea
- Fatigue
- Nausea, diaphoresis
- Can be silent! (common in diabetics, elderly)
- ECG manifestations: ST-segment depression, T-wave inversion
- Biochemical results: no elevationof troponins in pure ischemia → if there's elevation it means myocardial injury (not just ischemia)
Consequences[edit | edit source]
- Acute
- Transient LV dysfunction (↓ contractility)
- Arrhythmias
- Worsening HF symptoms
- If prolonged:
- Myocardial infarction
- Post infarction complications: mechanical rupture, cariogenic shock
Sources[edit | edit source]
- Amboss.
- Kumar, Abbas, Aster. Robbins Basic Pathology.
- First Aid for the USMLE Step 1 2024.
