What is an aortic aneurysm?

Aneurysm is a pathological dilation of segment of blood vessel, true aneurysm involves all three layers, pseudoaneurysm intima and media are disrupted and dilated segment is lined by adventitia only and sometimes perivascular clot. Fusiform aneursym affects entire circumference of vessel diffusely dilated artery, saccular aneursym only a portion of circumference outpouching of vessel wall. Aortic aneurysms can be classified by location (abdominal/thoracic, descending aorta usually contigouos with infra-diaphragmatic aneurysms thoracoabdominal aneurysms.