Aneurysms are abnormal local dilations of arteries,which vary considerably in size. Predisposing factors include atheroma,hypertension and defective formation of collagen in the arterial wall.
COMPLICATIONS OF ANEURYSM.
If an aneurysm ruptures,haemorrhage follows,the consequences of which depend on the site and the extent of the bleed. Rupture of the aorta is likely to be fatal,while bleeding into the subarachnoid space can also cause death,or permanent disability. Aneurysm damages the blood vessel endothelium,making it rougher than usual ,which increases the risk of clot formation. Clots may block circulation locally,or elsewhere if they travel in the blood stream as emboli. The swelling associated with the distended artery can cause pressure on local structures such as other blood vessels,nerves or organs.
TYPES OF ANEURYSM.
- Fusiform or spindle-shaped distensions occur mainly in the abdominal aorta. They are usually associated with atheromatous changes.
- Saccular aneurysms bulge out on one side of the artery. They may be congenital,or be associated with defective collagen production or with atheromatous changes.
- Dissecting aneurysms occur mainly in the arch of the aorta,caused by infiltration of blood between the endothelium and tunica media,beginning at a site of endothelial damage.
