Aortic aneurysm

Question 1

What is an aortic aneurysm?

Answer 1

A localised enlargement of the abdominal aorta such that the diameter is> 3 cm or> 50% larger than normal diameter (normal diameter = 2cm).

Question 2

What are the 2 types of aneurysms a pt could have?

Answer 2

1. True aneurysms involve all three layers dilating together (intima, media & adventitia) 
   - Saccular: asymmetrical shaped aneurysms balloon to one side of the blood vessel because one side has had to put up with higher blood pressure.
   - Fusiform: symmetrical dilatation on all sides of the blood vessel
2. False aneurysm (pseudoaneurysm) - collection of blood in the outer layer only (adventitia) which communicates with the lumen e.g., after trauma.
   - Most are infrarenal (below renal arteries) 

Question 3

What can cause an aortic aneurysm?

Answer 3

• There are NO specific identifiable causes 
• Unruptured aneurysms occur due to degeneration of elastic lamellae and smooth muscle loss.
• Weakened blood vessel wall struggled to contain pressure of pumping blood = diameter of lumen increases.
• Ruptured AAAs can leak into retroperitoneal space or intraperitoneal space.

Question 4

What are the risk factors for an aortic aneurysm?

Answer 4

• Smoking 
• Hypertension 
• Dissection producing a false lumen 
• Family history 
• Male 
• Age 
• Atherosclerosis (e.g. angina, myocardial infarction, stroke, claudication)
• Hyperlipidaemia 
• Connective tissue disorders: Marfan’s syndrome, Ehlers-Danlos syndrome 
• Inflammatory disorders: Behcet’s disease, Takayasu’s arteritis
• Bacterial infections (mycotic aneurysm)
  (DIABETES thought to be protective)

Question 5

Summarise the epidemiology of AAA

Answer 5

● Ruptured AAA:125 deaths per million in ages 55-59
● AAA screening programme being introduced in UK – all males >65 – ultrasound scan
● Unruptured AAA: 3% of >50 yrs, male: female ratio 3:1

Question 6

What are the presenting symptoms of an aortic aneurysm?

Answer 6

1. Unruptured
   o NO SYMPTOMS
   o Usually an incidental finding
   o May have pain in the back, abdomen, loin or groin
2. RUPTURED
   o Pain in the abdomen – intermittent or continuous; radiates to back, iliac fossae or groin
   o Pain may be sudden or severe
   o Syncope – low blood pressure
   o Shock
   NOTE: degree of shock depends on site of rupture and whether it is contained

Question 7

What signs of an aortic aneursym can be found on physical examination?

Answer 7

● Pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta
● Abdominal bruit
● Retroperitoneal haemorrhage can cause Grey-Turner’s sign (flank bruising) 
● Bleeding due to rupture can cause hypovolaemic shock - low BP/ high HR [hypotension, tachycardia]

Question 8

What investigations are used to diagnose/ monitor an aortic aneurysm?

Answer 8

1. Aortic Ultrasound/ ABDO US (very sensitive and specific in diagnosing AAA)→ Do not delay diagnosis and management of a ruptured AAA while waiting for the results of imaging (does not tell you if ruptured)
   - CT Angiogram needed to visualise a ruptured AAA to assist operative planning
2. Screening programme: single abdominal ultrasound is offered to all males aged ≥ 65 

Question 9

How is an aortic aneurysm managed?

Answer 9

1. Regular Surveillance (ultrasound) → 3-4.4cm = every year or 4.5-5.4cm = every 3 months
2. If Ruptured (or symptomatic) or ≥5.5cm or rapidly enlarging (>1cm/yr) → surgery = open repair or EVAR (endovascular repair of abdominal aneurysm)
   - 2 week wait referral to vascular surgery for repair (unless ruptured/symptomatic, then emergency surgery)

Question 10

What complications may arise following an aortic aneurysm?

Answer 10

1. Cardiovascular 
   - Rupture of AAA (high mortality rate) 
   - Thromboembolism –> can lead to leg pain 
   - Fistulas e.g. aortovenous/aortoenteric 
2. Renal: Ureteric obstruction - due to pressure effect, present with renal colic 
3. Impaired sexual function: Impotence and retrograde ejaculation due to damage to nerves