Ischemia: Definition, Causes, and Consequences of Inadequate Blood Supply

Ischemia is the restriction of blood flow (and thus oxygen) to a tissue, caused by vascular occlusion.

Common Causes

• Atherosclerotic plaque rupture/thrombosis
• Embolism (thrombus, air, fat)
• Vasospasm (e.g., Raynaud's, coronary spasm)
• External compression (compartment syndrome, tumor)
• Hypotension/shock (global hypoperfusion)

Clinical Manifestations

• Pain (angina, claudication, abdominal angina)
• Numbness, paresthesia
• Weakness, paralysis (neurologic ischemia)
• Organ dysfunction (renal, hepatic, mesenteric)

Outcome

Prolonged ischemia → infarction (tissue death). Timely reperfusion (thrombolytics, PCI, surgery) salvages viable tissue.