What is an aneurysm defined as?
- AAA dilatation > 1.5 times normal AP diameter
- True aneurysm: dilatations involve all layers of the arterial wall
- False (pseudo)aneurysm: blood collection in outer layer (adventitia) only
What are the two forms of aneurysms?
- Fusiform (most AAAs)
- Sac-like (Berry aneurysms)
Causes of aneurysms?
- Atheroma
- Infections
- Inflammatory
- Connective tissue disorders
Complications of aneurysms?
- Fistulae
- Rupture
- Thrombosis/embolism
- Pressure on other structures
Screening of aneurysms?
- Men offered abdominal US from 65-75
- Selective screening based on risk factors
Symptoms & signs of a ruptured AAA?
- Abdominal pain radiating to the back
- Expansile abdominal mass (expands and contracts)
- Shock
Describe an unruptured AAA?
- >3cm diameter
- Normal after 50 yrs(Men 1.7cm, women 1.5cm)
- Failure of elastic proteins within the ECM
- Often asymptomatic and incidental finding on abdominal exam
What makes AAA rupture more likely?
- Smoking
- Female sex
- Hypertension
- Positive family history
Describe surgery for unruptured AAA?
- Surgery for:
- Aneurysms >5.5cm, expanding >1cm/yr, symptomatic
- Stenting (EVAR) procedure
Describe overview of open AAA repair?
- Laparotomy, dissection to the AA
- Clamping of the artery below renal arteries and in the iliac arteries
- Aneurysm is opened:
- IMA and lumbar arteries ligated
- Tube or bifurcated graft are sutured into the aorta to exclude the aneurysm
- Aneurysms sac is sutured over the graft to reduced infection rates
Describe EVAR?
- Endovascular stent inserted via the femoral artery
- Less mortality than major surgery but higher graft complications
- eg endoleak: blood may leak into aneurysm
Complications of open AAA repair?
- Intra-operative complications:
- Haemorrhage
- Injury to surrounding structures
- Early complications:
- Infection
- Blood clots
- Late complications:
- Hernia
- Adhesions
Describe the emergency management of a ruptured abdominal aneurysm?
- Inform vascular surgeon, experienced anaesthetist
- Crossmatch blood, catheterise
- Insert 2 large bore cannulase
- Treat shock with O rhesus negative blood
- Prophylactic antibiotics eg co-amoxiclav
- Surgery:
- Clamping of aorta above the leak
- Tube graft inserted
- If iliac aneurysm: trouser graft, leg attached to each iliac artery
What infectious disease is an ascending aortic aneurysm associated with?
Tertiary syphilis
Name another cause of an adominal pulsatile mass?
- Tumour of pancreas or stomach
- Aortic passess between these structures
Abdominal aorta anatomy
Pathophysiology of AAA?
- Obliteration of collage and elastin in the media and adventitia
- Smooth muscle loss
- Infiltration of lymphocytes and macrophages
What are the different classifications of AAA?
- Congenital
- Accelerated in patients with Biscupid AV or Marfans
- Infectious
- Staphylococcus and salmonella are most common causes
- Inflammatory
Common presentations of AAA
Differentials for AAA?
- Diverticulitis
- No pulsatile abdominal mass
- CT scan shows normal aorta
- Irritable bowel syndrome (IBS)
- Bloating, stool frequency
- More common in women
- Appendicitis
What is the most common site for aneurysmal disease required treatment?
Infrarenal aorta
What reasons might a patient survive a ruptured AAA?
- Bleed into retroperitoneum which tamponades the leak
- Intense vasoconstriction of nonessential circulatory beds
- Development of an intense prothrombotic state
- BP drops which limits blood loss
What must be screened for in patients with AAA?
- Popilteal aneurysms
- Ultrasound
Describe the management of popliteal aneurysms?
- Exclusion of the aneurysm
- With bypass using the long saphenous vein
