AAA and Rupture

Question 1

What is a AAA?

Answer 1

An aneurism is an artery that is dilated by >50%. This is caused by loss of elastic lamellae and damage to the smooth muscle (which can be brought about by damage to the vessel wall). An Abdominal aortic aneurism is therefore a dilatation of the abdominal that is >3cm wide (the aorta is normally only 2cm). The most common site of a AAA is Infra-renal but above the aortic bifurcation.

Aneurisms are classified into a true aneurysm (where all the layers of the vessel are affected), or a false aneurysm (where only the outer layers are affected, causing blood to collect between the tunica media and adventitia of the vessel. Do not confuse a false aneurism with an aortic dissection! An aortic dissection is a tear in the tunica intima, causing blood to pool between the tunica intima and media, creating a false lumen. Aneurisms are at risk of rupture when they get larger, this is a surgical emergency, with 50% of patient not making it to hospital and 50% of those not making it through the surgery.

Question 2

What are the causes of an aneurysm

Answer 2

Common – Atheroma, Chronic Hypertension, Connective Tissue disorders (Ehlers Danlos, Marfans)

Others – Infective Endocarditis, Aortitis, Syphilis, Trauma

Question 3

What will you find on a history taking of a AAA

Answer 3

Symptoms:
An abdominal aortic aneurism is often asymptomatic apart from a possible pulsatile mass felt in the abdomen
Rupture - Classic Triad of Severe Chest/Upper back Pain, Pulsatile Abdominal Mass and Shock/Collapse

Risk Factors: 
Previously known AAA
High Blood pressure 
Smoking
Age > 65
Peripheral Vascular Disease 
Connective tissue disorder 

Differentials:
Aortic Dissection – Tearing type pain that radiates to the back, does not present with classic triad
Renal Stones – If the patient has groin pain, however this will be colicky type pain

Question 4

What will you find on examination of someone with a AAA

Answer 4

End of the bed:
Very unwell
Signs of shock
Hands:
Weak Pulses 
Abdomen:
Pulsatile Abdominal Mass
Abdominal Bruit
Legs:
Weak Pulses

Question 5

What investigations will you order in a AAA?

Answer 5

Bedside:
ECG – To rule out an MI

Bloods:
Amylase - Rule out pancreatitis
Troponin - To rule out an MI
FBC – To look at the Hb level, to assess severity of bleed and need for transfusion
Cross-match - They are bleeding
Clotting - They are bleeding
U&E - Going to be given lots of drugs and may require surgery
LFT - Going to be given lots of drugs and may require surgery

Imaging:
US – In unstable patients this may be all you have time to order
CXR – Can see thoracic aortic aneurisms, also rule out other causes of chest pain e.g. Pneumothorax
AXR – Will show a calcified lesion
Only CT stable patient, if not take them straight to theatre, do not do any other investigations that will waste time
Every male at age 65 is invited for a screening US to look for any abdominal aneurism

Question 6

What is the treatment of a ruputred AAA?

Answer 6

Resuscitation:
A-E approach
Get IV Access (2 wide bore cannulas)/Give O2 to maintain sats of 94+ /Attach 12 lead ECG
Assessment with AMPLE history and brief examination
Get help – Prepare a theatre, get an anaesthetist and vascular surgeon
Refer to ITU
Insert a urinary catheter
Frequent Observations - Constant or 15 minutely
Give O- blood if no cross match if in shock
Permissible Hypotension - Keep systolic BP < 100 to limit bleeding

Medical:
Pre-Operative Prophylactic antibiotics

Surgical:
Open repair - Clamp Aorta and insert a prosthetic graft to fix the leak
Endovascular Stent Repair

Question 7

What is the emergency treatment of a ruptured AAA?

Answer 7

Resuscitation
A-E approach
Get IV Access (2 wide bore cannulas)/Give O2 to maintain sats of 94+ /Attach 12 lead ECG
Assessment with AMPLE history and brief examination
Get help – Prepare a theatre, get an anaesthetist and vascular surgeon
Refer to ITU
Frequent Observations - Constant or 15 minutely
Give O- blood if no cross match if in shock
Permissible Hypotension - Keep systolic BP < 100 to limit bleeding

Medical:
Pre-Operative Prophylactic antibiotics

Surgical:
Open repair - Clamp Aorta and insert a prosthetic graft to fix the leak
Endovascular Repair

Question 8

What is the treatment of a stable AAA

Answer 8

Lifestyle:
Regular Ultrasound monitoring – >3cm Yearly, >4.5cm 6-Monthly, >5cm 3-Monthly
Reduce CVS risk Factors
May not drive if aneurism >6.5cm

Medical:
Reduce CVS risk factors – BP Control, Lipid control, Dual Antiplatelet therapy

Surgery:
All patients with an aneurism >5.5cm or with rapid expansion (>1cm/year) are offered elective surgery.
Endovascular repair (Requires 10 yearly CT scans to check for endovascular stent m0vmenet, but smaller operating
Open repair – Bigger surgery but no follow up required and lower complication rate post op.
If patient can survive open surgery, then that is preferred. As lower risk of long term complication and lower post op workload