An aneurysm is a ballooning weak spot in a vessel wall
As the bulge grows, rupture risk rises toward uncontrolled bleeding. True aneurysms involve all three arterial wall layers; false ones are contained leaks beside the vessel. The deadliest sit in the brain’s circle of Willis or along the aorta.
An aneurysm is a localized outward bulge—often compared to a bubble—where a blood-vessel wall is abnormally weak. It may be inherited or acquired, can seed clots that embolize, and becomes more dangerous as it enlarges because rupture can mean catastrophic bleeding. Though any vessel can host one, especially lethal sites include cerebral aneurysms of the circle of Willis, thoracic aortic aneurysms, and abdominal aortic aneurysms. Heart attacks can also leave ventricular aneurysms. The Greek root aneurysma simply means dilation.
Classification starts with wall integrity. A true aneurysm involves all three arterial layers—intima, media, and adventitia—and includes atherosclerotic, syphilitic, congenital, and post-infarct ventricular forms. A false aneurysm, or pseudoaneurysm, is blood that has fully exited the vessel yet remains trapped by surrounding tissue until it clots shut or bursts free; trauma, angiography, grafting, or arterial injection can create that pocket. Shape offers another axis: saccular “berry” aneurysms are spherical, often 5–20 cm across in the description given, with a neck and dome that matter for endovascular coiling; fusiform aneurysms are spindle-shaped, variable in length, and can span large stretches of aortic arch, abdominal aorta, or iliac arteries.
Location finishes the map. Arterial aneurysms outnumber venous ones. Cardiac sites include coronary arteries, ventricular walls, and the sinus of Valsalva. Aortic disease divides into thoracic and abdominal aneurysms. Morphology alone does not name the underlying disease, but neck size helps predict whether coiling is feasible. The clinical dread is not the bulge itself so much as the day the wall gives way—or the clot it sheds into the bloodstream.
Source: Aneurysm
