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Arteries can sometimes undergo localised expansion. When an artery expands to one and a half its normal size, it is called aneurysmal. Aneurysms can affect any artery in the body and even the heart.
Whilst there are numerous causes for aneurysm formation, the commonest in the Western World is degeneration "or breaking down" of the arterial wall. Other causes include congenital connective tissue diseases, infection and injury. The commonest and most familiar site for aneurysm disease is the abdominal aorta. The aorta is the main artery in the body. Other common sites include the popliteal arteries (arteries behind the knee joints) and the thoracic part of the aorta. In the majority of patients, aneurysms remain silent and are only discovered either incidentally when a scan is requested for another condition or when the aneurysm starts to cause complications. Aortic aneurysms tend to affect men much more than women. There is also a familial tendency for developing aneurysms particularly amongst male siblings. Whilst the majority of aneurysms can remain silent for many years, they invariably cause serious complications once they become symptomatic. The most serious of these complications is rupture. This happens when the aneurysm wall becomes so thin that it could not stand the blood pressure within. The aneurysm wall then ruptures leading to sudden and often massive blood loss. Abdominal aortic aneurysms are notorious for such a complication which is almost certainly lethal unless emergency successful surgery is performed. Another complication related to aneurysms is embolisation. As aneurysms form, the blood flow inside them becomes slower at certain parts. The blood then clots and forms a thrombus (a type of a blood clot). If part of a thrombus falls into the blood stream it forms what is called an embolus. An embolus travels with the blood until it reaches the origin of a smaller artery where it becomes lodged. This complication is common with aneurysms of the popliteal artery but not wit abdominal aortic aneurysms. An uncommon but recognised complication of aneurysms is pressure on surrounding structures. A large aneurysm in the pelvis can, for example, obstruct a ureter (outflow tract from the kidney) by directly compressing it. Abdominal aortic aneurysm disease affects approximately 6% of men over the age of 65. It is much less frequent in females, however, aneurysm rupture occurs at smaller sizes and has a worse outcome in females. Whilst the exact cause "or causes" of aneurysm formation remain unknown, the disease tends to run in families particularly on the mail side. St Richard's Hospital has long pioneered the research into abdominal aortic aneurysm epidemiology thanks to the tremendous effort of its now retired vascular surgeon Alan Scott. Alan realised that the early detection and treatment of aortic aneurysms can significantly reduce the incidence of death due to ruptured abdominal aortic aneurysm. For the last 21 years, St Richard's Hospital has been running an aneurysm screening program for its local population. Approximately, 2500 scans are conducted each year. All men living in our area automatically get an invitation to join the program upon reaching the age of 65. Those who have an aneurysm are invited to return for further scans at regular intervals. |
The commonest aortic aneurysm is that of the abdominal aorta. The aneurysm starts below the origin of the renal arteries and either stops at or extends into the two main branches to the legs.
An abdominal aortic aneurysm will rupture when its wall becomes too thin to stand the pressure from within. Aneurysm rupture is a very serious condition that carries a mortality rate of up to 85%
A large none ruptured abdominal aortic aneurysm
A ruptured abdominal aortic aneurysm. This patient presented with abdominal and back pain. |
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