Aortic aneurysm Flashcards
What is an abdominal aortic aneurysm?
An abdominal aortic aneurysm (AAA) is a condition where an area of the abdominal aorta bulges out. This is usually asymptomatic, however, it has the potential to rupture, leading to haemorrhage and rapid death.
What is the epidemiology of AAA?
AAA affects more males than females, with a prevalence of 1.3% in men > 65 years in the UK.
Why is it considered that atherosclerosis may be a contributing factor to AAAs?
Atherosclerotic plaques are thought to compress the aortic media, leading to ischaemia and wall weakening
Where does the abdominal aorta begin and end?
The abdominal aorta begins at T12 and ends at L4, dividing into the right and left common iliac arteries.
What is the normal diameter of the aorta?
<2cm
What is the pathophysiology of AAAs?
- Atherosclerosis causes inflammation, which leads to infiltration by macrophages and deposition of immune complexes in the aortic wall.
- There is elastin depletion, collagen degradation and smooth muscle loss
- this results in dilation in all layers of the wall
Define ‘aneurysm’:
the permanent dilation of the artery to twice the normal diameter
What is a true aneurysm?
in true aneurysms, the arterial wall forms the wall of the aneurysm while in false aneurysms, surrounding tissue forms the wall of the aneurysm
Where do abdominal aortic aneurysms most commonly occur?
Below the renal arteries
Give 4 broad causes of aneurysms:
1) atherosclerosis
2) infection
3) trauma
4) genetic conditions (Marfan’s, Ehlers-Danlos)
What 3 locations can AAAs be?
- Juxta-renal (Located within 1 cm of the renal arteries)
- Supra-renal (starting above the renal arteries)
- Infra-renal (starting below the renal arteries)
What is a saccular AAA?
A spherical outpouching
What is a fusiform AAA?
A diffuse and circumferential dilation
Name 10 risk factors for AAA?
- Smoking
- Family history
- Increased age
- Hyperlipidaemia
- History of atherosclerosis
- History of other aneurysms
- Hypertension
- COPD
- History of connective tissue disorders
- European ancestry
Give 3 infections that can cause aneurysms:
1) syphilis
2) E. coli
3) Salmonella
In which demographic group is AAA screening offered?
men aged 65-74
Name 10 differential diagnoses for AAA?
Diverticulitis
Renal colic
Biliary colic
Cauda equina syndrome
Spinal disc prolapse
Appendicitis
Ovarian torsion
Gastrointestinal haemorrhage
Bowel obstruction
Mesenteric artery occlusion
What type of screening is used for AAAs?
Ultrasound
What is the screening plan for AAA’s less than 5.5cm?
they should continue surveillance by the screening programme
What is the referral scheme for AAA more than 5.5cm?
they should be seen by a vascular specialist within 2 weeks
When is a contrast-enhanced CT angiography used?
used to confirm rupture AAA and for operative planning to assess anatomy and suitability for open and endovascular surgery in elective and emergency surgery)
What is the conservative management if aorta is less than 5.5cm?
Lifestyle advice: including referral to stop smoking services
Antiplatelet therapy: aspirin 75mg OD
Statins
Appropriate anti-hypertensives if BP >140mmHg
Give the size range for a ‘small’ AAA and the associated management plan:
3.0-4.4cm: annual ultrasound review and GP review
Give the size range for a ‘medium’ AAA and the associated management plan:
4.5-5.4cm: cardiovascular prevention therapy
At what size is an AAA considered for elective repair?
Greater than 5.5cm
True or false: most AAAs are asymptomatic
True
What are the general principles of surgical management for AAAs?
Open aortic repair or endovascular aortic repair (EVAR).
Open repairs have an arterial line, central venous line, epidural, and urinary catheter, and most have an NG tube inserted in the anaesthetic room
When is endovascular aortic repair (EVAR) considered?
- Patients with other co-morbidities
- Women of any age
- Men over 70 yrs old
This is due to the lower perioperative morality and decreased length of hospital stay
What procedure is used if the AAA is juxta-renal or supra-renal or too complex for standard EVAR?
Fenestrated EVAR
What is fenestrated EVAR?
Fenestrated EVAR allows blood flow to the renal arteries and other branching arteries (coeliac and superior mesenteric artery).
How is EVAR performed?
EVAR is performed by inserting a stent graft through the femoral arteries under radiological guidance. The stent allows the blood to be diverted through the graft instead of the aneurysm sac
What is an endoleak?
Endoleak is a common complication of endovascular aneurysm repair (EVAR) that occurs when blood flow persists within the aneurysm sac after stent-graft insertion.
What is a type 1 endoleak?
Blood is flowing into the aneurysm sac due to an incomplete seal between the stent and the aneurysm neck from above or below. This puts pressure on the walls of the aneurysm, increasing the risk of rupture.
What is a type 2 endoleak?
Blood is back-bleeding into the aneurysm sac from branch arteries (inferior mesenteric artery and lumbar arteries). This is less dangerous than type 1 as it is under low pressure
What is a type 3 endoleak?
Blood is flowing into the sac due to defects in the graft material or the seal between graft components. This is high pressure and dangerous.
What is a type 4 endoleak?
Blood flowing into the sac through the stent–graft fabric pores. This stops once a patient’s post-operative coagulation status returns to normal.
What is a type 5 endoleak?
AAA expansion with no radiographic sign of a leak site.
Give two types of elective surgical repair used to treat large AAAs:
1) laparotomy (open repair) inserting a mesh graft to prevent rupture
2) endovascular aneurysm (stent inserted via the femoral artery to insert the mesh graft)
What AAA finding may be found on abdominal examination?
pulsatile and expansile mass
Give 4 presentations associated with a ruptured AAA:
1) tachycardia
2) hypotension
3) profound anaemia
4) sudden death
How are ruptured AAAs managed?
Immediate management of a ruptured AAA should include:
- IV access (and limited fluid resuscitation)
- Analgesia
- Antibiotic prophylaxis
- Major haemorrhage protocol activation where appropriate.
- Blood transfusion if Hb <100 g/L with intraoperative bleeding
It is key to not over-correct the BP as this could exacerbate the rupture. BP should be managed to aim for a target systolic blood pressure of 70-90mmHg (this is called permissive hypotension).
what is abdominal compartment syndrome?
This is where the intra-aortic pressure exceeds 20mmHg, leading to organ failure.
This requires a laparostomy and delayed closure.
Abdominal compartment syndrome can occur following rupture repair.
What is the mortality rate for a ruptured AAA?
1.There is an 80% mortality rate from ruptured AAA.
- Surgical repair of ruptured AAA has a 35-37% mortality rate.
Name 7 early postoperative complications?
- Postoperative ileus
- AKI
- Bowel ischemia
- Spinal cord ischaemia
- Pseudoaneurysms
- Distal embolisation
- Retrograde ejaculation
Other than AAAs, give another type of aortic aneurysm:
thoraco-abdominal aneurysm
Where are thoraco-abdominal aneurysms found?
ascending or descending aortic arch
Which type of aneurysm is most commonly associated with Marfan’s syndrome?
ascending thoraco-abdominal aneurysm
Give 4 symptoms associated with rapid expansion of a thoraco-abdominal aneurysm:
1) severe chest pain
2) stridor
3) haemoptysis
4) hourseness
What investigation is used to diagnose a thoraco-abdominal aneurysm?
CT or MRI
What size must a thoraco-abdominal aneurysm be for operative repair?
greater than 6 cm
