EVAR (endovascular aneurysm repair)

Why are we operating?

Relining an abdominal aortic aneurysm from inside: a fabric-covered stent graft delivered up the femoral arteries and deployed across the sac, excluding it from pressure without opening the abdomen.

Indication: Infrarenal AAA at threshold (about 5.5 cm, or rapid growth), with anatomy that offers a sealing zone below the renal arteries and iliac access that admits the device.

The operation in 4 steps

1. 01Planning on the CT

   The CT angiogram is measured: neck length and angle below the renals, sac dimensions, iliac diameter and tortuosity, and the device is chosen and sized to the millimetre.

   Why: EVAR is won or lost at the workstation. The graft seals by radial force against healthy wall; a short, angled or conical neck has no such wall, and no deployment technique rescues a plan that never had a seal.

2. 02Femoral access

   Both common femoral arteries are punctured or exposed at the groin, wires passed up into the aorta under fluoroscopy, and closure devices pre-deployed for the percutaneous route.

   Why: The femoral triangle is this operation's only incision, and its complications, haematoma, dissection, occlusion, are the commonest of the whole procedure. Respecting a calcified access vessel is a skill in itself.

3. 03Deployment

   The main body is advanced and deployed just below the lowest renal artery, the contralateral limb gate cannulated, and the limbs extended into the iliacs; angiography checks every landing zone.

   Why: The renal arteries are the ceiling and the internal iliacs are the floor: the graft must seal between them without covering either. The gate cannulation is the operation's most tested exercise in catheter skill.

4. 04Completion and surveillance

   Completion angiography looks for endoleak, moulding balloons finish the seals, access is closed, and the patient enters lifelong imaging surveillance.

   Why: An excluded sac only stays excluded if every seal holds; endoleak is EVAR's signature complication and the reason the follow-up never ends. Type I and III leaks pressurise the sac and are fixed, not watched.

Danger zones

• Femoral artery

  Every access, every anastomosis, every groin stab wound: this is the vessel in question.

• Femoral vein

  Immediately medial to the artery, the structure a misplaced arterial puncture finds, and the wall of the femoral canal.

• Femoral nerve

  Lateral and OUTSIDE the femoral sheath; retractor injury costs knee extension.

Anatomy you need

The infrarenal aorta the graft relines and the iliac and femoral highway it travels up: the whole operation happens inside what you see.

What can go wrong

• Postoperative bleeding

  Tachycardia first, hypotension late; falling urine output; a distending abdomen or rising drain output.

• Venous thromboembolism

  Unilateral leg swelling, or sudden dyspnoea, pleuritic pain, tachycardia, sometimes the only sign is unexplained hypoxia.