Endovascular Aneurysm Repair

PROCEDURE OF THE DAY

EVAR

EVAR which stands for Endovascular Aneurysm Repair (or Endovascular Aortic Repair), is a type of Endovascular surgery used to treat an abdominal aortic aneurysm or AAA.

Patient screening

Before patients are deemed to be a suitable candidate for this treatment, they have to go through a rigorous set of tests. These include a CT scan of the aorta and blood tests. The CT scan gives precise measurements of the aneurysm and the surrounding anatomy. In particular the calibre/tortuosity of the iliac arteries and the relationship of the neck of the aneurysm to the renal arteries are important determinants of whether the aneurysm is amenable to endoluminal repair.

The procedure

The procedure is carried out in a sterile environment, usually a theatre, under x-ray fluoroscopic guidance. It is carried out by a vascular surgeon or an Interventional Radiologist who collaborate on most cases. The patient is either given a full GA (general anaestheic) or an epidural.

Vascular 'sheaths' are introduced into the patient's femoral arteries, through which the guidewires, catheters and eventually, the Stent Graft is passed.

Diagnostic angiography images or 'runs' are captured of the aorta to determine the location on the patient's renal arteries, so the stent can be deployed below these. The main 'body' of the stent graft is placed first, with the 'limbs' which join on to the main body and sit in the iliacs, placed later.

The idea is that the covered stent, once in place acts as a false lumen for blood to travel down, and not into the surrounding aneurysm sac. This therefore immediately takes the pressure off the aneurysm, which itself will thrombose in time.

Complications

Systemic

Myocardial infarction, congestive heart failure, arrhythmias, respiratory failure, renal failure

Procedure related

Dissection, malpositioning, renal failure, thromboembolizaton, ischemic colitis, groin hematoma, wound infection

Device related

Migration, detachment, rupture, stenosis, kinking

Endoleaks

An endoleak is a leak into the aneurysm sac after endovascular repair. Four types of endoleaks exist:[1]

* Type I - Perigraft leakage at proximal or distal graft attachment sites (near the renal and iliac arteries)
* Type II - Retrograde flow from collateral branches such as the lumbar, testicular and inferior mesenteric arteries
* Type III - Leakage between different parts of the stent (at the anastomosis between components)
* Type IV - Leakage through the graft wall




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