Introduction
This topic covers four groups of vascular disease: aneurysms (localised abnormal dilations of an artery or the heart), aortic dissection (blood splitting the aortic wall), varicose veins and the venous thrombotic conditions phlebothrombosis and thrombophlebitis. For each you should give definition, cause, morphology and complications.
Aneurysms: definition and types
An aneurysm is a localised, permanent, abnormal dilation of a blood vessel or of the heart wall. It may be congenital or acquired.
- True aneurysm: the dilated wall still contains all three layers (intima, media, adventitia), although they are thinned. Examples: atherosclerotic and syphilitic aortic aneurysms, ventricular aneurysm after myocardial infarction.
- False aneurysm (pseudoaneurysm): a defect in the wall lets blood escape into the surrounding tissue, where it forms an extravascular haematoma that stays connected with the lumen and is walled off by clot and connective tissue. Typical causes: trauma, a ruptured ventricular wall after infarction, an anastomotic leak.
- Dissection is a different process: blood enters the wall itself and splits its layers (see below), rather than forming an outpouching.
By shape, aneurysms are saccular (a spherical outpouching of part of the wall, 5 to 20 cm) or fusiform (a circumferential, spindle-shaped dilation along a segment, up to 20 cm).