Abdominal Aortic Aneurysms

on 12.11.06 with 0 comments



Aneurysms: are localized abnormal dilations of vessels; most common and significant are abdominal aortic aneurysms.

Causes: any that results in damage or weakness of vessel walls

  • Atherosclerosis and cystic medial degeneration (two most common)

  • Syphilis

  • Vasculitis (e.g. polyarteritis nodosa - PAN)

  • Hypertension: role in dissecting aneurysms

  • Trauma (e.g. false aneurysms, arterio-venous aneurysms)

  • Congenital defects: familial predisposition to other causes

  • Infections (mycotic aneurysms): from septic embolisms or direct septicaemia


Abdominal Aortic Aneurysms: are typically found in men >50 years old.

The risk of rupture increases with the maximal diameter of the bulge: minimal risk if <5cm>5cm; operative mortality is 5% for unruptured aneurysm but >50% after rupture.

Because atherosclerotic peripheral (aortic) vascular disease is usually accompanied by severe coronary atherosclerosis, patients with abdominal aortic aneurysms have a high incidence of ischemic heart disease.

Complications: morbidity and mortality of (aortic abdominal) aneurysms are secondary to

  • Rupture into peritoneal cavity or retroperitoneal tissues with massive fatal haemorrhage.

  • Impingement on adjacent structures (e.g. compression of ureter or erosion of vertebrae)

  • Occlusion of proximate vessels by either extrinsic pressure or superimposed thrombosis (e.g. renal, mesenteric arteries)

  • Embolism from mural thrombosis

Sometimes there may be inflammation around the aneurysm in the adventitia, together with fibrous scarring. Rarely the aneurysm may become infected from a bacteraemia.

Category: Pathology Notes

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