Aneurysms - Hypertension and vascular diseases

Aneurysms

Definition

An aneurysm is defined as an abnormal focal dilation of an artery (see Table 2.12).

Pathophysiology

An arterial aneurysm may be true or false. A true aneurysm is enclosed by all three layers of the arterial wall. A true aneurysm may be further subdivided into saccular in which there is a focal out-pouching or fusiform where there is dilation of the whole circumference of the vessel. A false (pseudo) aneurysm occurs following penetrating trauma when there is a pulsatile haematoma, which is in contact with the arterial lumen.

Aneurysms tend to slowly enlarge, causing local pressure problems. They may dissect and cut off blood supply to tissue or rupture with resulting haemorrhage.

Altered flow patterns predispose to thrombus formation, which may embolise to distal arteries or cause occlusion at the site of the aneurysm.

Investigations

CT and ultrasound scanning can demonstrate the position and type of aneurysm. Arteriography or 3-D reconstruction using MRI is used to outline the anatomy.