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Arterial Aneurysms

Aneurysms are defined by dilatation > 50% of original diameter. There are 3 types of it:

  • True - Involves all layers of the arterial wall, and can be fusiform (e.g. AAA) or sac-like (e.g. berry aneurysms)

  • False (pseudoaneurysms) - Collection of blood in the outer layer only

  • Dissecting - Tear of t.intima, and blood enters between the layers to separate them

Causes - Trauma, Atheroma, Infection


Risk factors - DM, Obesity, HTN, Smoking, Alcohol, Dyslipidaemia


Complications - Rupture (presents with hypovolemic shock), Thrombosis, Embolism


It's presentation depends on the location of the aneurysm:

  • Cerebral - may present with sensory/motor signs if pressing on nerves, but will present as a SAH if it ruptures

  • Abdominal aorta - usually asymptomatic and found incidentally or once ruptured


General management:

  • Control of modifiable risk factors e.g. DM, HTN, Smoking

  • Depending on its size, conservative or surgical management can be taken


Abdominal Aortic Aneurysm (AAA)

Atherosclerosis → inflammation → infiltration by macrophages and deposition of immune complexes in the aortic wall. This causes elastin depletion, collagen degradation and smooth muscle loss, therefore resulting in dilatation in all layers of the aortic wall = Aneurysm.


Asymptomatic AAA

If < 5.5cm, manage conservatively with surveillance and risk management:

  • Surveillance:

    • 3.0-4.4cm → repeat USS yearly

    • 4.5-5.4cm → repeat USS every 3 months

  • Risk management:

    • Lifestyle advice e.g. smoking cessation

    • Anti-platelet therapy

    • Statin

    • Good BP control (maintain systolic < 140mmHg)


If ≥5.5cm or >4cm + rapidly growing (> 1cm per year), manage surgically:

  • Open aortic repair

    • Preferred for the younger and healthier patients

    • Graft lasts longer but has more risks than EVAR

  • Endovascular aortic repair (EVAR)

    • Preferred in older, co-morbid patients

    • Has less peri-operative mortality and decreased length of hospital stay

    • Has more risk of long-term complications e.g. leakage

“Endovascular Repair” © National Institutes of Health (Licensed under CC-BY 4.0) https://creativecommons.org/licenses/by/4.0/


Ruptured AAA:

This is a surgical emergency so has to be approached with the following:

  • Bedside: A-E assessment, ECG

  • Bloods: FBC, U&E, G&S, Crossmatch, Clotting screen

  • Imaging: CT angiogram (this shouldn’t delay the treatment in unstable patients. The aim is to assess, keep them stable, and then take to theatre asap).


Management:

  • IV fluids

  • Prophylactic antibiotics

  • Blood transfusion


N.B. Very important not to over-correct the BP as it could exacerbate the rupture. BP should be aimed at systolic between 70-90mmHg (called permissive hypotension).



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