From the Guidelines
Abdominal aortic aneurysm (AAA) is a serious condition characterized by the dilation of the abdominal aorta to 3.0 cm or greater, with a high risk of rupture and mortality.
Pathophysiology
The pathophysiology of AAA involves inflammatory, proteolytic, and neovascular changes that result in the loss of elastin and accumulation of fibrous material in the arterial wall 1.
- Risk factors for AAA include a family history of aortic aneurysm or cardiovascular disease, being male, smoking, hypertension, hypercholesterolemia, peripheral artery disease, increasing age, genetic syndromes, and inflammatory diseases 1.
- Factors associated with expansion and rupture of AAA include large aneurysm diameter, rapid growth, smoking, hypertension, high peak wall stress, a history of cardiac or renal transplant, decreased forced expiratory volume, and being female 1.
Clinical Significance
AAA is a significant health concern due to its high mortality and morbidity associated with rupture, with an estimated 75% to 90% risk of death from an AAA rupture 1.
- Screening or imaging surveillance is widely used to detect AAA that requires repair, with a generally accepted threshold of an aneurysm diameter exceeding 5.5 cm in men and 5.0 cm in women 1.
- Elective surgical repair is considered the best way to prevent rupture and can be performed using an open surgical or endovascular approach 1.
- Imaging modalities such as ultrasound, CT angiography, and MR angiography provide an accurate and reproducible assessment of aneurysm size, while radiographs and aortography provide limited evaluation 1.
From the Research
Pathophysiology of Abdominal Aortic Aneurysm (AAA)
- The pathophysiology of AAA is related to an initial arterial insult causing a cascade of inflammation and extracellular matrix protein breakdown by proteinases, leading to arterial wall weakening 2.
- The disease is characterized by a progressive dilatation of the vascular wall that can lead to its rupture, a fatal phenomenon in more than 80% of cases 3.
- Risk factors for the development of an aneurysm include tobacco use, hypertension, a family history of AAA, and male sex 4.
Clinical Significance of AAA
- AAA is a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world 5.
- The risk of AAA development is considerably higher for men of advanced age with a history of smoking 5.
- Screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80% 5.
- Asymptomatic patients with an AAA should be medically optimized before repair, including institution of beta blockade, and symptomatic aneurysms require urgent surgical attention 4.
Management of AAA
- Medical management includes the control of risk factors that may prevent growth, stabilize the aneurysm, and prevent rupture 2.
- Surgical management prevents rupture of high-risk aneurysms, most commonly predicted by size, and involves a multidisciplinary approach to evaluate the patient's risk profile and to develop an operative plan involving either an endovascular or an open surgical repair 2.
- The patient must be carefully monitored post-operatively for complications and, in the case of endovascular repairs, for endoleaks 2.
- The treatment of patients with asymptomatic aneurysms is limited to periodic monitoring with imaging tests, control of cardiovascular risk factors, and treatment with statins and antiplatelet therapy 3.