Abdominal Aortic Aneurysm

Question 1

Define aneurysm

Answer 1

Abnormal dilation of a blood vessel more than 50% of its normal diameter

Question 2

Definition of AAA

Answer 2

Dilation of abdominal aorta greater than 3cm

Every 8 mm increase in aneurysm diameter increased risk of death by 1.34

Question 3

Risk factors

Answer 3

Smoking

HTN

Hyperlipidaemia

FH

Male gender

Increasing age

DM is a negative risk factors why is not understood

Question 4

Aetiology of AAA is largely unknown

Give possible causes

Answer 4

Atherosclerosis

Trauma

Infection

Connective tissue disease like Marfan’s ED, Loey Dietz or inflammatory disease like Takayasu’s

Question 5

Clinical features

Answer 5

Usually asymptomatic and detected on incident finding or screening.

Symptomatic…

Abdominal pain

Back or loin pain

Distal embolisation leading to ALL

Aortoenteric fistula

Question 6

Examination findings

Answer 6

Pulsatile mass felt in the abdomen above the umbilical level

Rarely signs of retroperitoneal haemorrhage

Question 7

Explain screening for AAA

Answer 7

Any man when they are 65 should be offered an abdo US scan.

Around 1.1% of all screened are diagnosed.

Most men with detected AAA will spend 3-5 years in surveillance prior to reaching the threshold for elective AAA repair

Question 8

Dx

Answer 8

Renal colic

Diverticulitis

IBD

IBS

GI haemorrhage

Appendicitis

Ovarian torsion

Ovarian rupture

Splenic infarctions

Pancreatitis

Question 9

Investigations

Answer 9

Any suspected AAA should initially be investigated by USS

Once USS has confirmed diagnosis -> follow-up CT scan with contrast when at threshold diameter of 5.5 cm

This provides more anatomical details in order to determine suitability for endovascular repair

Question 10

Management of any AAA <5.5 cm

Answer 10

Monitored via Duplex USS

3. 0-4.4 cm = yearly USS
4. 5-5.4 cm = 3mo USS

Smoking cessation

Improve BP control

Commence statin and aspirin therapy

Weight loss

Question 11

What needs to be done (not med/surg related) about any AAA >6.5 cm

Answer 11

Requires notification to the DVLA and disqualifies from driving until the aneurysm is repaired

Question 12

Indications of surgical intervention

Answer 12

AAA >5.5cm

AAA expanding at >1cm/year

Symptomatic AAA in a patient who is otherwise fit

Question 13

Surgical indication in an unfit patient

Answer 13

You may wait until the AAA is at 6cm or more before repair

Question 14

Main approaches of surgical intervention

Answer 14

Open repair

Endovascular repair

Both have similar long term outcomes

Question 15

Explain open repair

Answer 15

Midline laparotomy or long transverse incision

Expose the aorta and clamp it proximally + iliac arteries distally

The segment is then removed and replaced with a prosthetic graft.

Question 16

Explain endovascular repair

Answer 16

A graft is drawn through the femoral arteries and fixing the stent across the aneurysm

Question 17

Important complication of endovascular repair

Answer 17

Endovascular leak where an incomplete seal forms around the aneurysm leading to blood leaking around the graft

Question 18

How is an endovascular leak found?

Answer 18

They are often asymptomatic so regular surveillance by USS is required.

If left untreated the aneurysm can expand and rupture.

Question 19

Classification of endoleaks

Answer 19

Type 1 - Leak occurs at the graft ends due to inadequate seal. It is most common following thoracic aneurysm repairs.

Type 2 - Sac filling occurs from a branch vessel, this is most common in AAA repairs. (2a = single vessel, 2b = multiple)

Type 3 = Leak occurs through a defect in the graft fabric like a hole

Type 4 - Graft fabric porosity (often resolves with cessation of anticoagulants)

Type 5 - Continued expansion without any demonstrable leak

Question 20

Complications of AAA

Answer 20

Rupture

Retroperitoeal leak

Emobilisation

Aortoduodenal fistula

Question 21

Clinical features of ruptured AAA

Answer 21

Abdo pain

Back pain

Syncope

Vomiting (20% of AAA ruptures will rupture anteriorly)

Question 22

Examination findings of ruptured AAA

Answer 22

Haemodynamically unstable

Pulsatile abdo mass and tenderness

Question 23

Classic triad of ruptured AAA

Answer 23

Flank or back pain

Hypotension

Pulsatile abdo mass

(Only happens in 50% of patients)

Question 24

Management of ruptured AAA

Answer 24

Immediate high flow O2, IV access with 2x large bore cannulae + urgent bloods (FBC, U&Es, clotting) + crossmatch for minimum of 6 units

Shock should be treated very carefully
Raising the BP will dislodge clot and may lead to further bleeding.

Aim for BP to be at 100mmHg or less termed permissive hypotension, as long as the patient is conscious and clear the BP is generally adequate.

The patient should be transferred to the local vascular unit

Question 25

Management of ruptured AAA if patient is unstable

Answer 25

Require immediate transfer to theatre for open surgical repair

Question 26

Management of ruptured AAA in stable patient

Answer 26

CT angiogram to determine whether the aneurysm is suitable for endovascular repair isntead of open.