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Aneurysms, ischaemic limb and occlusions

Medicine > Cardiovascular

Background knowledge 🧠

Definition

  • An aneurysm is a localised dilation of an artery, typically involving a weakened vessel wall.
  • Can occur in various arteries but most common in the aorta.
  • Ischaemic limb refers to a significant reduction in blood flow to the limb, typically due to arterial occlusion.
  • Occlusion is the complete blockage of a blood vessel, leading to reduced perfusion of tissues.

Epidemiology

  • Abdominal aortic aneurysms (AAA) affect 1-2% of men aged over 65.
  • Aneurysms are more common in men than women.
  • Peripheral artery disease (PAD) and occlusions occur more commonly with advancing age.
  • Risk factors include smoking, hypertension, and hyperlipidaemia.
  • Acute limb ischaemia (ALI) is seen in approximately 1.5 cases per 10,000 annually.

Aetiology and pathophysiology

  • Aneurysms develop due to structural weakening of the vessel wall (e.g., from atherosclerosis).
  • Hypertension, trauma, and genetic conditions (e.g., Marfan syndrome) contribute to aneurysm formation.
  • Ischaemic limb is caused by arterial occlusion, typically due to embolism, thrombosis, or trauma.
  • Occlusions occur due to atherosclerotic plaque rupture or thrombus formation, reducing arterial blood flow.
  • Tissue ischaemia leads to cellular damage and necrosis if untreated.

Clinical Features 🌡️

Symptoms

  • Aneurysms may be asymptomatic until rupture or dissection.
  • Abdominal or back pain in AAA, pulsatile mass.
  • Ischaemic limb: Sudden severe pain, paraesthesia, and weakness.
  • Intermittent claudication in chronic limb ischaemia.
  • Acute limb ischaemia: pale, painful, cold limb.

Signs

  • Pulsatile abdominal mass in AAA.
  • Absent or reduced pulses in affected limb.
  • Cold, pale, or cyanotic skin in ischaemic limb.
  • Delayed capillary refill time.
  • Skin ulceration or gangrene in chronic ischaemia.

Investigations 🧪

Tests

  • Ultrasound is first-line for AAA diagnosis.
  • CT angiography for detailed assessment of aneurysms and occlusions.
  • Ankle-brachial pressure index (ABPI) to assess peripheral artery disease.
  • Doppler ultrasound to assess blood flow in limbs.
  • Blood tests: FBC, U&Es, clotting profile to assess general health and rule out other causes.

Management 🥼

Management

  • AAA: elective repair if >5.5 cm in men or symptomatic.
  • Endovascular aneurysm repair (EVAR) or open surgery for large aneurysms.
  • Acute limb ischaemia: urgent revascularisation (surgical or thrombolytic).
  • Chronic limb ischaemia: lifestyle modification, antiplatelets, and statins.
  • Angioplasty or bypass surgery for occluded arteries.

Complications

  • Rupture of AAA can lead to life-threatening haemorrhage.
  • Acute limb ischaemia may result in amputation if untreated.
  • Thromboembolism from aneurysms or occlusions.
  • Post-repair complications: graft infection, endoleaks in EVAR.
  • Gangrene in chronic ischaemia.

Prognosis

  • AAA rupture has a high mortality rate (80%+).
  • Early surgical intervention in acute limb ischaemia improves limb salvage rates.
  • Chronic ischaemia prognosis depends on risk factor management and timely intervention.
  • Complications such as gangrene or amputation worsen outcomes.

Key points

  • Early diagnosis and intervention in aneurysms and ischaemia are key to reducing mortality and morbidity.
  • Screening for AAA is recommended for men aged over 65.
  • Smoking cessation and risk factor control are essential in preventing progression.
  • Prompt recognition of acute limb ischaemia saves limbs and lives.

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Cardiovascular