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In search of biological and radiological markers of aneurysm instability
12/4/13

Abdominal aortic aneurysms (AAA) are a common disorder affecting 4 % of the population over the age of 65. The risk of rupture is currently estimated according to diameter, but while some large aneurysms may remain intact, it isn’t rare for small aneurysms torupture. Teams at the CHU hospital (Department of Cardiovascular Surgery, Department of Nuclear Medicine) and the University of Liège (Laboratory of Connective Tissues Biology, GIGA) are on the trail of markers that can predict the instability of abdominal aneurysms.

Aortic thoracic abdominal aneurysmFor most of us, the term aneurysm is generally associated with the notion of rupture and usually a fatal outcome for the patient. This type of death is particularly shocking owing to its violent nature, because the disease’s slow evolution prior to rupture is  most often  asymptomatic. The distinction between the formation of the aneurysm and its rupture isn’t always easy to discern or understood by non-specialists.

An aneurysm is a localised and irreversible dilation of an artery wall. The appearance of this disorder is favoured by certain factors such as high blood pressure or smoking, among other things. The rupture of an aneurysm, and therefore the artery wall, causes significant and often uncontrollable bleeding. Depending on the location and the type of blood vessel concerned, this rupture can lead to the patient’s rapid death. 

In 95 % of cases, the aneurysms are located in the abdominal artery. “This isn’t a rare condition since it affects 4 % of the population over the age of 65. Furthermore, it is inevitable that the number of aneurysms detected will continue to increase, with the gradually aging population", explains Professor Natzi Sakalihasan, from the Department of Cardiovascular Surgery at Liège’s CHU, lead by Jean-Olivier Defraigne. Aortic aneurysms can be detected using a simple ultrasound scan.  However, owing to its often asymptomatic nature, it is often not detected before the rupture occurs. “The rupture is fatal in 60 to 85% of cases, most often even before the patient has been admitted to hospital”, Professor Sakalihasan stresses.  

Identifying dangerous aneurysms

In humans, the normal diameter of the abdominal aorta is 18 to 22 millimetres. “When its diameter reaches 30 millimetres or more, the dilation is considered as pathological”, Natzi Sakalihasan points out. Patients are therefore recommended to attend regular check-ups to monitor the evolution of the expansion of their aneurysm. In current medical practice, surgery is recommended when the aneurysm’s diameter has reached 55 millimetres, based on the principle that the more it expands, the higher the risk of rupture. 

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