[14] Abdominal Aortic Aneurysm Flashcards
What is an aneurysm?
A pernament and irreversible dilation of a blood vessel by at least 50% of the normal expected diameter
What can aortic aneurysms be classifed as?
Abdominal (the majority) and thoracic
What is the normal diameter of the abdominal aorta?
Approximately 2cm, increasing with age
What is an abdominal aortic aneurysm defined is, in terms of diameter?
An aortic diameter of 3cm or greater
What can aortic aneurysms be associated with?
Aneurysms elsewhere, e.g. in iliac artery or popliteal artery
Where do most AAAs arise?
Most AAAs arise from below the level of the renal arteries
Where to thoraco-abdominal aortic aneurysms extend?
From the thoracic aorta into the abdominal aorta to a variable degree, and may affect the origins of the visceral and renal arteries
What pathological processes are involved in the development of an aneurysm?
- Degradation of the elastic lamellae
- Leukocytic infiltrates
- Enhances proteolysis
- Smooth muscle cell loss
Which layers of the aorta are affected by the dilation in an aortic aneurysm?
All
What happens when the walls of the aorta dilate in an AAA?
They expand, but still contain all the blodo
What causes a false aneurysm (pseudoaneurysm)?
Leakage of blood through the arterial wall, but contained by the adventitia or surrounding perivascular tissue
What are the risk factors for an AAA?
- Severe atherosclerotic damage of the aortic wall
- Family history
- Tobacco smoking
- Male sex
- Increasing age
- Hypertension
- COPD
- Hyperlipidaemia
What are the causes of AAAs?
Most have no identifiable cause, but for a minority there is a specific cause, e.g.
- Trauma
- Infection with brucellosis, salmonellosis, tuberculosis, HIV
- Inflammatory diseases, e.g. Takayasu’s disease
- Connective tissue disorders, e.g. Marfan’s syndrome, Ehler’s-Danlos
How are most patients with an unruptured AAA diagnosed?
May be an incidental finding on clinical examination or on scans
What are the symptoms of an unruptured AAA?
Most patients who have an unruptured AAA have no symptoms. If symptoms are present, they may include;
- Pain in the back, abdomen, loin, or groin
- Patient or doctor may find pulsatile abdominal swelling
- Distal embolisation may produce features of limb ischaemia
- Ureterohydronephrosis
