embolism

An embolism is the sudden blockage of a blood vessel by an embolus, a detached intravascular mass that travels from a site of origin to a distant vessel. Emboli can be solid (for example, thrombus, vegetations, cholesterol crystals), liquid (such as fat, tumor cells, or atheromatous debris in some contexts), or gaseous (air or nitrogen). The resulting occlusion disrupts blood flow and can cause ischemia or infarction in the tissue supplied by the affected vessel.

Emboli originate from various sources. Venous thromboembolism is the most common source of pulmonary embolism, where a clot formed in the deep veins travels to the pulmonary arteries. Arterial emboli typically arise from the left side of the heart (for example, due to atrial fibrillation or myocardial infarction with wall motion abnormalities) or from atherosclerotic debris. Other emboli include fat emboli after long bone fractures, air emboli from trauma or medical procedures, and septic emboli from infective endocarditis or other infections.

Clinical features depend on the site and size of the embolus. Pulmonary embolism may cause sudden shortness of breath, chest pain, tachycardia, and hypoxia; arterial embolism can cause limb ischemia or organ dysfunction such as stroke or renal infarct; fat embolism syndrome may present with respiratory distress, neurologic symptoms, and petechiae 24–72 hours after injury.

Diagnosis relies on clinical assessment supported by imaging and laboratory tests. D-dimer testing, CT pulmonary angiography, ventilation–perfusion scanning, and ultrasound for DVT are commonly used; arterial embolism may require CT or MRI and vascular imaging.

Treatment focuses on restoring perfusion and preventing further embolization. Anticoagulation is standard for venous thromboembolism; systemic thrombolysis or surgical embolectomy is considered for massive or life-threatening embolism. Septic and air emboli are treated accordingly, with antibiotics and supportive care. Prevention emphasizes risk factor reduction, prophylactic anticoagulation in high-risk settings, early mobilization, and management of cardiac sources of emboli.