Definition

• A localized permanent dilation of the abdominal aorta >3 cm in diameter.

Epidemiology

• Incidence is reported to be 5– 10%.

Aetiology

• Almost all are caused by aortic atherosclerosis.

Pathogenesis

• Proteolytic enzymes weaken the media of the aorta, leading to aneurysmal change. • Increased levels of matrix metalloproteinases have been found in aneurysmal aortas. these enzymes are known to degrade elastin.

Presentation • Unruptured aneurysms are often asymptomatic and most are discovered incidentally on abdominal examination or imaging.

• Ruptured abdominal aortic aneurysms present as a surgical emergency with abdominal pain and shock.

Macroscopy

• the aorta is dilated, usually below the level of the renal arteries.

• extensive atherosclerosis is invariably present, often with secondary thrombosis and calcification.

 Histopathology

 • Aortic atherosclerosis shows intimal collections of lipid, inflammatory cells, and fibrosis. Complicated lesions may show haemorrhage in the plaque or overlying thrombus.

• Aortic aneurysms show severe atherosclerosis with marked loss of the media layer.

 Prognosis

• the natural history is that of gradual enlargement.

 • Risk of rupture is exponentially related to the diameter.

 • Mortality after rupture exceeds 80%.

• elective surgical repair should be considered for aneurysms with a maximum diameter of 5.5 cm or more.

مواضيع ذات صلة

Acute circulatory failure (cardiogenic shock)

Pulmonary hypertension

Pulmonary thromboembolism

Giant cell (temporal) arteritis

ابيضاض الدم النقوي المزمن Chronic myelocytic leukaemias

Infective endocarditis

تليف النقيMyelofibrosis

فقر الدم اللا مصنع ( اللا تنسجي ) Aplastic anemia

Septic shock

Distributive shock

Cardiogenic shock

Hypovolemic shock