- M M Thompson,
- P R F Bell
True arterial aneurysms are defined as a 50% increase in the normal diameter of the vessel. Clinical symptoms usually arise from the common complications that affect arterial aneurysms—namely, rupture, thrombosis, or distal embolisation. Although the aneurysmal process may affect any large or medium sized artery, the most commonly affected vessels are the aorta and iliac arteries, followed by the popliteal, femoral, and carotid vessels.
Abdominal aortic aneurysms
Aneurysms of the infrarenal abdominal aorta and iliac arteries coexist to such a degree that they may be considered a single clinical entity. Abdominal aneurysms usually affect elderly men (>65 years), with a prevalence of 5%. In England, abdominal aneurysm is responsible for over 11 000 hospital admissions and 10 000 deaths a year. Interestingly, unlike other atherosclerotic vascular disorders, the prevalence of abdominal aortic aneurysms is increasing rapidly, and aneurysmal rupture is now the 13th commonest cause of death in the Western world.
Although abdominal aneurysms may cause symptoms because of pressure on surrounding structures, about three quarters remain asymptomatic at initial diagnosis. With the exception of vague abdominal pain, clinical symptoms usually result from embolisation or rupture of the aneurysm.
The appearance of microembolic lower limb infarcts in a patient with easily palpable pedal pulses may suggest the presence of either popliteal or abdominal aneurysms. Additionally, patients with embolisation of mural thrombus from an abdominal aneurysm may present with acute limb ischaemia due to femoral or popliteal occlusion.
The diagnostic triad of hypovolaemic shock, pulsatile abdominal mass, and abdominal or back pain is encountered in only …