Background: The term aneurysm is derived from the Greek word ἀνεύρυσμα, meaning dilatation or widening [1]. An abdominal aortic aneurysm (AAA) is a widening of the abdominal aorta and is generally defined as a dilatation beyond a diameter of 3.0 cm. Due to the asymptomatic nature of most Aneurysms, diagnosis is commonly a result of screening or during routine examination with abdominal palpation. MATERIAL &METHODS: During a routine cadaveric dissection of the abdomen in the anatomy wet lab for medical students of St, James School of Medicine, Anguilla, an abnormal finding was seen in a 77-year-oldfemale cadaver. RESULTS: The aneurysm was fusiform in shape (Fig. 1) and was found to be unruptured. Its location was found between origin of renal arteries and the aortic bifurcation into common iliac arteries. CONCLUSION: A thorough knowledge of the anatomy and pathophysiology of aneurysms is required for successful endo-vascular grafts and good prognosis in unruptured cases.
Keywords: AAA(Abdominal aortic aneurysm), Aortic wall Thickening, Fusiform
Aneurysms are a multifactorial disease in which both genetic and environmental factors play a prominent role. The abdominal aorta begins at the aortic hiatus of the diaphragm at the 12th thoracic vertebra. It descends anterior to lumbar vertebrae and bifurcates into two common iliac arteries. The mean adult diameter of the aorta inferior to the origin of renal arteries measured by computed tomography is 19-21 mm (males) and 16-18mm (females), but there are ethnic variations. With advancing age, there is a progressive increase in abdominal aorta diameter in both sexes [2]
Aortic aneurysm is a focal localized dilatation of the vessel. The most common and serious aneurysms occur in the aorta (Hiratzka et al. 2010)[3].
The abdominal aortic aneurysm was referred to as a life-threatening condition. Tobacco use, increasing age, male sex, family history and hypertension are the major risk factors for abdominal aortic aneurysm (Ps, Dg, and C 1993)[4]. About 85% of aneurysms occur below the kidneys while the rest are either at the level of or above the kidneys (Kc 2014)[5]. Abdominal aortic aneurysm rupture occurs in 1-3% of men aged 65 or more, the mortality is 70-95% (Js et al. 2005)[6]. In the present cadaver study report, we describe a77-year female with an unruptured abdominal fusiform aortic aneurysm below the level of renal arteries in the abdomen
During a routine cadaveric dissection of the abdomen in the anatomy wet lab for medical students of St, James School of Medicine, Anguilla, an abnormal finding was seen in a 77-year-old female cadaver.
The aneurysm with a fusiform shape was noted (Fig. 1) and found unruptured. When the anterior abdominal wall was dissected and the abdominal
viscera (small intestine) were reflected, an aneurysm was observed between renal arteries and the aortic bifurcation. The inferior mesenteric artery was seen to arise from the lower end of the aneurysm. A tape was passed around the maximally dilated portion of the aneurysm to measure the circumference and the diameter was calculated using the formulae of a cylinder. The length of the aneurysm was also measured. A portion of the wall of the aorta was excised to measure the thickness.
An abdominal aortic aneurysm was located between renal arteries and the division of common iliac arteries. The aneurysm measured around 6 cm in length, 15cm in circumference and approximately 4.78 cm in diameter. No visible outgrowth was noted. No adhesions were seen to the surrounding structures. Inferior Vena Cava was noted as normal. All other branches arising from aorta were normal.
It was observed that the lumen was narrowed. There were no blood clots but the wall inside was black in color. The wall of the aorta at the aneurysm was thickened uniformly circumferentially, which measured about 1.5cm. There was no growth and bulging.
The most common location of Aortic aneurysm at the bifurcation of the aorta into the common iliac arteries. Occasionally, the ascending arch and descending thoracic aorta are affected (La 2001)[7]and commonly occurs in adults 60 years of age or older and has been reported to be four times more frequent in males (Stites J et al. 1989)[8]. In the present study, the aneurysm was found between renal arteries and the aortic bifurcation. In the present case, we found arterial wall was thickened after opening and no pressure effects were found during dissection similar clinical cases were reported by B.V. Murlimanju et al[9] and A Manitombi Devi1[10].
Aneurysms measuring greater than 5 cm tend to continue growing and rupture. At 6 cm there is a 25% chance of death due to rupture in one year and more than 50% chance of rupture in 5 years. At measures greater than 6 cm the chance of death due to rupture is 50% within the first year. The risk of rupture within 2 years is 75%, and within 5 years is 90% (Aggarwal et al.2011)[11]. In the present case, the aneurysm measured 6 cm in length, 4.78 cm in diameter and 15 cm in circumference and was found similar to the case reported by A Manitombi Devi [10] in which dimensions were 7 cm in length, 3.5cm in width, 11 cm in circumference, unruptured and very closer to the inferior venacava , and Aneurysm of 6cm in length was published in a research paper submitted by Reddy, A et., al [12] and 5.9cm length was noted in B.V. Murlimanju et al [9]
Aneurysms are characterized by structural disintegration of the aortic wall, consequent gradual aortic dilatation and ultimately rupture. Multiple factors are implicated in the pathogenesis of aortic aneurysms, which cause destructive changes to the connective tissues of the media and adventitia of the aortic wall, driving aneurysm formation and eventually rupture. In the first instance, the link between aneurysm formation and rupture is influenced by factors such as aneurysm size, expansion rate, gender, age, smoking, and family history.
In the present case, the aneurysm was un-ruptured, which was also noted in other studies The unruptured infrarenal abdominal aortic aneurysms are now resected with a low mortality rate but special problems continue to present challenges. Ruptured aneurysm was presented by Kate Clancy et al. [13]
AAAs are mostly asymptomatic and found incidentally. Aneurysm rupture is a medical emergency, and the risk of aneurysm rupture increases with increasing diameter, rapid expansion, symptomatic aneurysm and history of smoking. Medical management with beta-blockers, cessation of smoking and management of risk factors, such as dyslipidemia and hypertension, may be helpful in patients with small- to medium-sized aneurysms that are not treated surgically. AAA is still a cardiovascular disease with a high risk of death. Lifestyle changes have been proposed to prevent aneurysm progression and rupture. A thorough knowledge of the anatomy and pathophysiology of aneurysms is required for successful endo-vascular grafts and good prognosis in unruptured cases.
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