Aneurysms, ischaemic limb and occlusions Flashcards
What is the primary reason for screening abdominal aortic aneurysms (AAA)?
The majority of patients with AAA are asymptomatic, and screening is beneficial due to the high mortality associated with a ruptured AAA.
What is the recommended screening method for AAA in males aged 65?
A single abdominal ultrasound.
What are the interpretations and actions based on aorta width during screening?
Aorta width interpretation and actions are as follows:
- < 3 cm: Normal - No further action
- 3 - 4.4 cm: Small aneurysm - Rescan every 12 months
- 4.5 - 5.4 cm: Medium aneurysm - Rescan every 3 months
- ≥ 5.5 cm: Large aneurysm - Refer within 2 weeks to vascular surgery for probable intervention.
What characterizes low rupture risk in AAA management?
Low rupture risk is characterized by being asymptomatic with an aortic diameter < 5.5 cm, requiring abdominal ultrasound surveillance and optimization of cardiovascular risk factors.
What characterizes high rupture risk in AAA management?
High rupture risk is characterized by being symptomatic with an aortic diameter ≥ 5.5 cm or rapidly enlarging (>1 cm/year), requiring referral within 2 weeks to vascular surgery for probable intervention.
What is the treatment for high rupture risk AAAs?
Treatment includes elective endovascular repair (EVAR) or open repair if unsuitable. In EVAR, a stent is placed into the abdominal aorta via the femoral artery to prevent blood from collecting in the aneurysm.
A complication of EVAR is an endo-leak, where the stent fails to exclude blood from the aneurysm, usually presenting without symptoms on routine follow-up.
What primarily causes abdominal aortic aneurysms?
Abdominal aortic aneurysms occur primarily as a result of the failure of elastic proteins within the extracellular matrix.
What does an abdominal aortic aneurysm represent?
Aneurysms typically represent dilation of all layers of the arterial wall.
What is the normal diameter of the infrarenal aorta after age 50?
The normal diameter of the infrarenal aorta is 1.5cm in females and 1.7cm in males.
What diameter is considered aneurysmal?
Diameters of 3cm and greater are considered aneurysmal.
What is the primary event in the development of aneurysms?
The primary event is loss of the intima with loss of elastic fibres from the media.
What are major risk factors for the development of aneurysms?
Major risk factors include smoking and hypertension.
What are rare but important causes of aneurysms?
Rare but important causes include syphilis and connective tissue diseases such as Ehlers Danlos type 1 and Marfan’s syndrome.
What are the three main patterns of presentation in peripheral arterial disease?
- Intermittent claudication
- Critical limb ischaemia
- Acute limb-threatening ischaemia
What are the features of acute limb-threatening ischaemia?
1 or more of the 6 P’s:
- Pale
- Pulseless
- Painful
- Paralysed
- Paraesthetic
- ‘Perishing with cold’
What initial investigations should be performed for acute limb-threatening ischaemia?
A handheld arterial Doppler examination should be conducted. If Doppler signals are present, an ankle-brachial pressure index (ABI) should also be obtained.
What factors suggest thrombus in acute limb-threatening ischaemia?
- Pre-existing claudication with sudden deterioration
- Reduced or absent pulses in contralateral limb
- Sudden onset of painful leg (< 24 hours)
- Evidence of widespread vascular disease (e.g. myocardial infarction, stroke, TIA, previous vascular surgery)
What factors suggest embolus in acute limb-threatening ischaemia?
- No obvious source for emboli
- No history of claudication
- Clinically obvious source of embolus (e.g. atrial fibrillation, recent myocardial infarction)
- Evidence of proximal aneurysm (e.g. abdominal or popliteal)
What is the initial management approach for acute limb-threatening ischaemia?
ABC approach:
- Analgesia: IV opioids are often used
- Intravenous unfractionated heparin is usually given to prevent thrombus propagation
- Vascular review
What are the definitive management options for acute limb-threatening ischaemia?
- Intra-arterial thrombolysis
- Surgical embolectomy
- Angioplasty
- Bypass surgery
- Amputation: for patients with irreversible ischaemia
What are the three main patterns of presentation in patients with peripheral arterial disease?
- Intermittent claudication
- Critical limb ischaemia
- Acute limb-threatening ischaemia
What are the features of critical limb ischaemia?
1 or more of the following:
- Rest pain in foot for more than 2 weeks
- Ulceration
- Gangrene
Patients often report hanging their legs out of bed at night to ease the pain.
What ankle-brachial pressure index (ABPI) value is suggestive of critical limb ischaemia?
An ABPI of < 0.5 is suggestive of critical limb ischaemia.
What does an ABPI result of 1 indicate?
Normal
What does an ABPI result of 0.6-0.9 indicate?
Claudication
What does an ABPI result of 0.3-0.6 indicate?
Rest pain
What does an ABPI result of <0.3 indicate?
Impending limb loss
What is the presentation of a ruptured abdominal aortic aneurysm (AAA)?
The presentation may be catastrophic (e.g. sudden collapse) or sub-acute (persistent severe central abdominal pain with developing shock).
What is the mortality rate of a ruptured AAA?
Ruptured AAA has a very high mortality of almost 80%.
What are the features of a ruptured AAA?
Features include severe, central abdominal pain radiating to the back, a pulsatile, expansile mass in the abdomen, and patients may be shocked (hypotension, tachycardic) or may have collapsed.
What is the management for a suspected ruptured AAA?
A ruptured AAA is a surgical emergency requiring immediate vascular review with a view to emergency surgical repair.
What should be done for haemodynamically unstable patients with suspected ruptured AAA?
The diagnosis is clinical; these patients should be taken straight to theatre without a CT scan.
What approach should be considered for frail patients with multiple comorbidities and suspected ruptured AAA?
Consideration should be given to a palliative approach as it may represent a terminal event.
What should be done for haemodynamically stable patients with suspected ruptured AAA?
They may be sent for a CT angiogram where the diagnosis is in doubt, which may also assess the suitability of endovascular repair.
