Aneurysm
An abnormal bulging of a blood vessel wall due to a weak spot.
An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may result from hereditary conditions or acquired diseases and can serve as a nidus for clot formation and embolization. As an aneurysm increases in size, the risk of rupture rises, potentially leading to uncontrolled bleeding. Aneurysms can occur in any blood vessel, with particularly lethal examples including those of the circle of Willis in the brain, thoracic aortic aneurysms, and abdominal aortic aneurysms.
- classification
- True and false aneurysms; saccular or fusiform morphology; location-based
- common_locations
- Brain (circle of Willis), aorta (thoracic and abdominal), heart, legs, kidney
- risk_factors
- Diabetes, obesity, hypertension, tobacco use, alcoholism, high cholesterol, copper deficiency, increasing age, tertiary syphilis, connective tissue disorders
- size_threshold
- Abdominal aortic aneurysm defined as outer diameter over 3 cm; large if over 5.5 cm
- etymology
- From Greek ἀνεύρυσμα (aneurysma), 'dilation'
Lore & Background
Aneurysms are classified by type, morphology, or location. True aneurysms involve all three layers of the artery wall (intima, media, and adventitia) and include atherosclerotic, syphilitic, and congenital forms, as well as ventricular aneurysms following transmural myocardial infarctions. False aneurysms, or pseudoaneurysms, are collections of blood leaking completely out of a vessel but confined by surrounding tissue, often caused by trauma or percutaneous surgical procedures.
Reader's Guide
Aneurysms are significant because they represent a potentially life-threatening condition that can remain asymptomatic until rupture, which may lead to severe bleeding or stroke. Their classification by morphology—saccular (berry) or fusiform—and by location helps guide treatment decisions, such as endovascular coiling for saccular aneurysms with a defined neck. Risk factors include hypertension, tobacco use, and connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome. The pathophysiology involves weakening of the vessel wall due to factors such as infection (mycotic aneurysms), syphilis, or copper deficiency affecting elastin. Understanding the mechanics of aneurysmal vessels, which exhibit a J-shaped stress-strain curve and are prone to rupture under normal blood pressure, is crucial for prevention and management. Aneurysms remain a major focus of vascular medicine and neurosurgery.
Did You Know?
- The word 'aneurysm' comes from the Greek ἀνεύρυσμα, meaning 'dilation'.
- Saccular aneurysms are spherical and involve only a portion of the vessel wall, often filled partially or fully by a thrombus.
- Abdominal aortic aneurysms are usually asymptomatic but can cause lower back pain or lower limb ischemia in rare cases.
- Copper deficiency can cause aneurysms by decreasing lysyl oxidase activity, affecting elastin in vessel walls.
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