Aneurysms were first described by the 16th century anatomist and physician Vesalius, who believed they were simply a widening of the vessel (Collin et al 2009). An abdominal aneurysm (AAA) is a condition in which the abdominal aorta (a large blood vessel that supplies blood to the abdominal, pelvis and the lower limbs) becomes large and ballooning leading to the development of several symptoms. The condition more often occurs in males compared to females. It occurs more frequently in above the age 60. When the aortic aneurysm is larger than size, it is more likely to rupture causing life-threating problems. This is a medical emergency requiring critical care. This complication is present in about 20% of the people affected with AAA. Another complication with AAA is aortic dissection in which the innermost membrane of the blood vessel ruptures due to the intense pressure causing blood to be filled within the wall of the artery. The exact cause of the disorder has still not been understood clearly, but several risk factors may be present including:-
* High cholesterol levels
* Genetic factors
* Smoking (Albright JL. 2006 & Hallett JW. 2008)
Individuals affected with AAA initially may not have any symptoms. Symptoms of the condition usually develop suddenly due to rupture of the wall or breakage of the innermost wall. Sudden rupture of the abdominal aortic aneurysm, often without prior medical warning, is the 13th leading cause of morality in the US (Li, Z 2006). Some of the symptoms that can develop in AAA include:- * Abdominal pain (which may be severe, consistent and radiates to the legs, groin and the buttocks region)
* Pulsations in the abdomen & palpitations
* Nausea and vomiting
* Anxiety and agitation
* Abdominal rigidity
* Cold and clammy skin
* Presence of the abdominal mass
* Excruciating pain in the limbs and back, when the AAA ruptures
* Fatal outcomes in the case of ruptured AAA(Albright JL. 2006 & Hallett JW. 2008) When the AAA is small in size (less than 5 centimeters), no treatment is required. Antihypertensive may be needed to prevent any further complications from developing. Besides, if the individual has any risk factors that can worsen the condition, it needs to be rectified immediately (such as giving up smoking, weight reduction, lowering cholesterol levels, etc.). Periodic evaluations have been recommended to ensure that any risk can be identified and immediately taken care of (Albright JL. 2006 & Hallett JW. 2008). Surgery is required if the AAA is larger than 5.5 centimeters in size, as the risk for rupture or dissection is present. The Aneurysmal defect is repaired by inserting a surgical graft. This can be performed by two method namely the conventional approach or the endovascular approach. In the conventional approach, general anesthesia is utilized.
A surgical incision is made below the breast bone, the aneurysm defect identified, and the graft material sutured in position. The entire procedure takes about 5 hours and a stay of at least a week in the hospital is required. The second approach is the endovascular stent grafting in which regional anesthesia is administered and a catheter is introduced through the femoral artery present in the groin region. This catheter contains the stent graft. It is gradually guided into position using imaging techniques. Once it is position, the stent graft is opened ensuring a stable blood flow. The procedure takes about 3 hours can require a stay of about 3 days in the hospital (Albright JL. 2006 & Hallett JW. 2008).
Several imaging techniques play a very important role in diagnosing and treating AAA. These include ultrasound, CT scans and angiography. Abdominal ultrasound is one of the preferred examinations for AAA. Ultrasound of the abdomen is also required following convention surgery to monitor the repaired AAA closely. It is usually performed as an initial imaging modality due to several factors including:-
* Absence of ionizing radiation
* Low costs
* Easy availability (Radvany MG. 2006)
Angiography involves administration of a contrast media into the femoral artery present in the groin region and then taking X-rays to determine the condition of the abdominal aorta. It is very useful before conventional and endovascular surgery for planning. It also seems to be very useful in the case of aortic dissection. However, angiography also carries a few risks including:-
* Damage to the artery
* Infection of blood vessel
* Embolism and clot formation
* Bleeding and heart attack (Bentley-Hibbert S. 2007 & Radvany MG. 2006). If the abdominal ultrasound and AAA greater 5 centimeters, than a CT scan of the abdomen is required. The CT scan can better help to plan the surgical intervention as the images provide a lot of detail (including involvement of the renal arteries, size of the aneurysm, amount of calcification, presence of mural thrombi, etc.). The accuracy of CT scans is said to be 100%. They provide a lot of details regarding the size of the aneurysm and also about distal and proximal issues. CT even with contrast media cannot be utilized to study dissection aneurysm or the presence of the extent of mural thrombus.
They are also required following endovascular graft surgery for a period of 6 months as a post-procedural follow-up measure (Radvany MG. 2006). MRI scans of the abdomen are required when the side-effects of the contrast media used in other techniques could be potential damaging to the patient (in case of kidney or liver problems) or when radiation is contra-indicated. The images provide a lot of detail and are accurate. However, MRI cannot be performed in individuals with cardiac pacemakers. CT and MRI scanning also have other advantages including:- * Provides details regarding extent of involvement
* Determine involvement of major blood vessels (Radvany MG. 2006)
Albright JL. Abdominal aortic aneurysm. Medline Plus. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000162.htm Accessed October 20, 2012.
Bentley-Hibbert S. Aortic angiography. Medline Plus. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/003814.htm Accessed October 26, 2012.
Hallett JW. Aneurysms. 2008. The Merck Manual. Available at: http://www.merck.com/mmhe/sec03/ch035/ch035b.html Accessed October 26, 2012.
Li Z. Effects of blood flow and vessel geometry on wall stress and rupture risk of abdominal aortic aneurysms. Journal Of Medical Engineering & Technology [serial online]. September 2006;30(5):283-297. Available from: Computer Source, Ipswich, MA. Accessed October 24, 2012.
Radvany MG et al. Abdominal Aortic Aneurysm, Diagnosis. E-Medicine. 2006. Available at: http://www.emedicine.com/Radio/topic1.htm Accessed October 24, 2012.
Woodrow P. Abdominal aortic aneurysms: clinical features, treatment and care. Nursing Standard [serial online]. August 17, 2011;25(50):50. Available from: Advanced Placement Source, Ipswich, MA. Accessed October 24, 2012.
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