Aneurysm

• D: Abnormal localised dilation of a blood vessel

Classification

1. Congenital / Acquired:
   • Berry aneurysm (art. circle of Willis)
   • hypertension
2. True / False:
   • Full thickness (all three layers)
   • partial (outpouching of intima)
3. Shape:
   • Fusiform (entire circumference)
   • saccular (part of circumference)
   • dissecting
4. Cause: Atheroma, syphillis, trauma, inflammatory (PAN, Ank Spond), Iatrogenic, ischaemic, congenital, mycotic (following low grade infection), hypertension (Charcot-Bouchard aneurysm)
5. Anatomy:
   • Ascending aortic aneurysm
   • Descending - supra-renal (blood supply to gut, spinal cord), infra-renal

Complications

1. Thrombosis
2. Embolus
3. Haemorhage
4. Pressure effects - nerve, vertebral column
5. Fistulation

Indications for screening

1. All patients with risk factors should have USS at 65 years
2. Small aneurysms (4-5.5cm) should undergo ultrasound surveillance at 6 month intervals

Indications for surgery

1. Emergency
   • Rupture
2. Elective
   • Symptomatic aneurysm
   • Rapidly expanding
   • > 5.5cm

Elective mortality is 2-5% 

Management of Ruptured aneurysm

1. Resuscitation / stabilisation
   • Large bore cannulae, IV crystalloid, maintain relative hypotension (90-100 systolic)
   • Urinary catheter - UO
   • Adequate analgesia
   • Bloods: FBC, U/Es, LFTs, Amylase, Cross match 8 units of blood + FFP + platelets
2. Contact most senior surgeon / dedicated vascular team + anaesthetist
3. Arrange ITU bed
4. Surgery if unstable, imaging if stable (CT)
   • Risk of death - 50% survive to hospital, 25% die before operation
   • Operative complications - limb loss, ischaemic gut, renal failure

Aneurysm repair procedure

1. GA, supine, exposed groins (for embolectomy)
2. Access aorta
   • Long midline incision from xiphisternum to pubis, skirt left of umbilicus
   • Omentum, large bowel displaced superiorly
   • Pack small bowel to right
   • Duodenum displaced
   • Peritoneum dissected off aorta
3. Give IV heparin
4. Repair aneurysm
   • Clamp across neck and lower end of aneurysm sac
   • Incise sac longitudinally
   • Scoop out thrombus, atheromatous material
   • End-to-end anastamosis with prosthetic graft using prolene sutures
5. Test repair
   • Soft clamp applied below sleeve, release upper clamp
   • Repair lower end of anastamosis
6. Closure
   • Remove clamps (warn anaesthesist - may get hypotension)
   • Ensure haemostasis
   • Close aneurysm sac around repair
   • Close posterior peritoneum (avoids fistulation)
   • Mass closure of wound using looped 0-nylon/PDS
   • Close skin with clips
7. Go to intensive care - watch for complications
   • Vascular: haemorrahge, graft thrombosis, false aneurysm, distal embolism
   • Neurological: CVA, spinal ischaemia
   • GIT: ischaemic gut, aorto-enteric fistula, pancreatitis
   • Renal: ARF
   • Respiratory: ARDS
   • Cardiovascular: MI
   • Haematological: DIC

Endovascular stenting

1. Minimally invasive interventional radiology
2. Catheter places metal stent inside aorta
3. Indications:
   • Patients unsuitable for open surgery
   • Infra-renal aneurysms
   • Anatomy: proximal and distal neck of arteries must allow complete exclusion of aneurysm

Endovascular stenting procedure

1. GA / regional
2. Access femoral artery
3. Pass graft over guidewire
4. Deploy graft once in position
   • Graft achieves final shape through elasticity / thermal memory

Complications

• Infection
• Leakage
• Fracture of graft
• Graft migration
• Graft occlusion