Abdominal Aortic Aneurysm

Screening for aneurysms

- All men in the UK are offered a screening USS at 65 to detect asymptomatic AAA - Women aren't routinely screened but can be considered in women over 70 with risk factors such as: CVD, COPD, FH, Hypertension, hyperlipidemia, smoking

Low Rupture risk of AAA

- Asymptomatic, diameters <5.5cm - Monitor using USS and optimise CV risk factors

Pathophysiology of aneurysms

- Loss of the tunica intima with loss of elastic fibres from the media - This is associated, and potentiated by an increase in proteolytic activity and lymphocytic infiltration

What are the risk factors for abdominal aortic aneurysms?

- Male - Increasing age - Smoking - Hypertension - FH - Existing CVD - High LDL levels - Connective tissue disorders (Marfans' syndrome, Ehlers-Danlos Syndrome)

How do patients with AAAs usually present?

- Often asymptomatic OR - Non-specific abdominal pain - Pulsatile and expansile mass in the abdomen when palpated with both hands

What complications are there in AAAs?

- Rupture - Thoracic aneurysm

High Rupture risk of AAA

- Symptomatic, diameter >5.5cm or rapidly enlarging (>1cm/year) - Refer within 2 weeks. to vascular team f - Treat with elective endovascular repair (EVAR) or open repair if unsuitable

Why does an aneurysm occur?

1. Aneurysm occur due to weakening of the blood vessel wall 2. When weakened, vessels struggle to contain pressure of the blood causing dilation 3. Dilation of. blood vessel occurs (aneurysm) 4. When the diameter of the vessel of the lumen increases, pressure of flowing blood also increases 5. Positive feedback loop occurs of continuous bulging of arterial wall causing an increase in aneurysm size

How are aneurysms managed?

1. Conservatively: the risk of AAA progression can be reduced by managing certain risk factors: smoking, diet, exercise, optimising hypertension, diabetes and hyperlipidemia. Surveillance yearly for small aneurysms and 3 months for medium aneurysms. 2. Repair (surgery): often for symptomatic, fast growing, large and potentially rupturing aneurysm

Which are the most common sites for AAs to occur?

40% in thoracic aorta 60% in Abdomen 95% of AAAs occur below the point the renal arteries branch

Mortality rate of ruptured AAA

80%

What is an aneurysm?

Ballooning of a blood vessel caused by a weakness in the blood vessel wall, usually where it branches

What is Marfan's Syndrome?

Congenital connective tissue disease causes aortic dilatation and mitral valve prolapse due to a decrease in fibrin (weakens blood vessels)

What is an abdominal aortic aneurysm?

Dilation of the abdominal aorta, with a diameter of more than 3cm

Complications of EVAR

Endo-leak: the stent fails to exclude blood from the aneurysm, usually presents without symptoms on routine follow-up

Investigations in AAAs

FBC, U+Es, Coagulation screen, cross match blood type

What are the types of "true" aneurysm?

Fusiform (symmetrical) - artery wall balloons symmetrically Saccular (berry aneurysm) - artery wall only balloons out on one side (may be due to weakening)

What is permissive hypotension?

Hold off on putting fluids in if we know there is bleeding inside because we don't want to knock the clot off and cause even more bleeding

What does AAA repair entail?

Inserting an artificial graft into the section of the aorta affected by the aneurysm by: - Open repair (laparoscopic) - EVAR

What is Ehlers-Danlos syndrome?

It is an Autosomal Dominant genetic disorder that leads to defective Collagen Synthesis. It is a Risk Factor for Aortic and other Aneurysms.

Describe how aneurysms are classified

Normal: less than 3cm Small: 3-4.4cm Medium: 4.5-5.4cm Large: 5.5cm +

What is a "false" aneurysm (pseudoaneurysm)?

Other tissues form the wall of the aneurysm Not an actual aneurysm, it is caused by a small hole in the blood vessel wall which allows blood to leak out and pool around the vessel Can look like both a fusiform or saccular aneurysm

AAA and driving

Patients with an aneurysm above 6cm must inform the DVLA, and stop driving if above 6.5cm

When are AAAs referred to vascular team urgently?

Patients with aortic aneurysm diameter above 3cm, more urgently if more than 5.5cm

Where is the most common site for peripheral aneurysms?

Popliteal artery, mostly affects men. 50% also have AAA

Symptoms of ruptured AAA

Severe abdo pain that may radiate to the back or groin Haemodynamic instability (hypo, tachy) Pulsatile, expansile mass Collapse Loss of consciousness

What is a "true" aneurysm?

The wall of the artery forms the aneurysm

How are aneurysms diagnosed?

USS CT angiogram

What is Elective Endovascular Repair (EVAR) ?

When a stent is placed into the Abdominal Aorta via the femoral artery to prevent blood from collecting in the aneurysm

Grey Turner's sign

bruising in flank area (lower back area) - can be an indication of AAA rupture