Aortic aneurysm (CV) Flashcards
Define abdominal aortic aneurysm (AAA).
Permanent pathological dilation of the aorta with a diameter >1.5x (or >3cm) expected anteroposterior diameter of that segment, given the patient’s sex and body size
Describe the pathophysiology of AAA.
- primary event is loss of the intima with loss of fibres from the media
- associated with and potentiated by increased proteolytic activity and lymphocytic infiltration
- aneurysms typically represent dilatation of all layers of the arterial wall
Where do the majority of AAAs occur?
Below the renal arteries (infrarenal)
What is the difference between a true aneurysm vs a pseudoaneurysm?
- a true aneurysm is abnormal dilatation involving all layers of the arterial wall - these can be fusiform (most AAAs) or sac-like
- false aneurysms (pseudoaneurysms) involve a collection of blood in the outer layer only (adventitia) which communicates with the lumen e.g. after trauma
What is the difference between unruptured and ruptured AAAs?
- unruptured aneurysms occur due to degeneration of elastic lamellae and smooth muscle loss
- ruptured AAAs can leak into retroperitoneal space (relatively haemodynamically stable) or intraperitoneal space (likely to result in shock)
Which groups does AAA affect most? (2)
- M>F
- 60-70 years old
What is the screening population for AAA?
Males >65 years - single USS done at 65
What are the clinical features of an unruptured AAA?
- ASYMPTOMATIC
- usually an incidental finding on USS or CT
- may have pain in back, abdomen, loin or groin
What are the clinical features of a ruptured AAA?
- life-threatening
- severe, central abdominal pain radiating to the back(/iliac fossae/groin)
- palpable pulsative + expansile abdominal mass
- shock - hypotension + tachycardia
- syncope
What might you see on examination in ruptured AAA? (7)
- pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta
- abdominal bruit
- Grey-Turner’s sign (retroperitoneal haemorrhage)
- hypotension + tachycardia (shock)
- loss of consciousness
- pallor
- embolic phenomena - lower leg purpura
What is the most important risk factor for AAA?
Smoking
What are some risk factors for AAA? (7)
- smoking
- Fx
- increased age (60-70)
- male
- connective tissue disorder (Marfan syndrome)
- atherosclerosis
- hypercholesterolaemia
What is the first-line investigation for AAA?
Aortic ultrasound
What should you not do while waiting for aortic ultrasound results for AAA?
Do not delay diagnosis and management of a ruptured AAA while waiting because imaging does not tell you that AAA is ruptured
When do we do a CT angiogram for AAA?
Only in haemodynamically stable patients to visualise ruptured AAA
Who is ultrasound screening offered to for AAA?
All men >65 in UK to determine diameter of abdominal aorta
What bloods can be done for AAA? (5)
- FBC
- clotting screen
- renal function
- LFTs
- ESR & CRP
What imaging modalities can be used for AAA? (4)
- aortic ultrasound - 1st line
- CT angiogram - to visualise ruptured AAA in haemodynamically stable
- CT with contrast - show whether aneurysm has ruptured
- MRI angiography
What are some differential diagnoses for AAA? (8)
- diverticulitis - constipation, LLQ pain, leukocytosis
- ureteric colic - loin–>groin
- IBS - flares lasting 2-4 days
- IBD
- appendicitis
- ovarian torsion
- GI haemorrhage
- mesenteric artery aneurysms/acute occlusion
What is the management plan for unruptured AAA?
Regular ultrasound surveillance + aggressive cardiovascular risk management (smoking cessation, antiplatelet therapy with aspirin, statins, antihypertensives, lifestyle)
How often should you repeat ultrasound for AAA of different sizes?
- if small AAA (3-4.4cm) - offered yearly repeat US
- if medium AAA (4.5-5.4cm) - offered repeat ultrasound every 3 months
- if large AAA (>5.5cm) or symptomatic - elective surgery generally recommended (refer within 2 weeks)
When do you do surgical management of an aortic aneurysm? (3)
- ruptured (or symptomatic) - emergency surgery
- > /=5.5cm
- rapidly enlarging (>1cm/year)
What is the surgical management plan for ruptured AAA? (6)
- open surgical repair or EVAR (endovascular aneurysm repair)
- resuscitation measures (oxygen, IV access, arterial and urinary catheter, FFP)
- perioperative Abx
- analgesia
- VTE prophylaxis (enoxaparin/heparin)
- IV fluids (saline or Hartmann’s solution)
What are some complications of AAA? (10)
- abdominal compartment syndrome
- ileus, intestinal obstruction and ischaemic colitis
- AKI
- post-implantation syndrome
- amputation due to limb ischaemia
- spinal cord ischaemia
- impaired sexual function
- anastomotic pseudoaneurysm
- aortic neck dilation
- graft infection
Name a complication of EVAR (AAA surgery).
- endo-leak if the stent fails to exclude blood from aneurysm (persistent blood flow outside graft and within aneurysm sac after EVAR)
- presents without symptoms on routine follow-up
What is the prognosis of a ruptured AAA?
Patients will not survive to reach theatre (very poor)
