embolus
Summary
An embolus is an intravascular mass (thrombus, air, fat, amniotic fluid, or foreign material) that travels through the bloodstream and lodges in a distant vessel, causing vascular occlusion. Most commonly consists of dislodged thrombi from deep veins (pulmonary embolism) or left heart (systemic embolism). Can cause tissue ischemia, infarction, or death depending on location and size.
Detail
An embolus forms when material breaks off from its original location and travels through the circulation until it becomes lodged in a vessel too small for it to pass through. The most common type is thromboembolism, where a blood clot (thrombus) dislodges from sites like deep leg veins (leading to pulmonary embolism) or left atrial appendage in atrial fibrillation (leading to stroke). Other types include fat emboli (from bone fractures), air emboli (from IV procedures or decompression), septic emboli (infected material from endocarditis), and amniotic fluid emboli (during childbirth). The clinical consequences depend on the organ affected: pulmonary emboli cause chest pain, dyspnea, and right heart strain; cerebral emboli cause stroke; coronary emboli cause MI; and peripheral emboli cause limb ischemia. Virchow's triad (stasis, hypercoagulability, endothelial damage) predisposes to thromboembolism. Treatment involves anticoagulation, thrombolytics, or surgical embolectomy depending on severity and location.
Sources
- Robbins and Cotran Pathologic Basis of Disease
- First Aid for the USMLE Step 1
- Harrison's Principles of Internal Medicine
- Pathoma
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