Failure of the stent-graft to totally exclude blood flow to the aneurysm sac. Defined as a persistent blood flow outside the lumen of the endoluminal graft but within an aneurysm sac. Major cause of complications, and thus failure in endoluminal treatment of AAA. Causes continued pressurization of the aneurysm sac and puts the patient at risk of rupture.
Type I endoleak: blood flow into the aneurysm sac due to incomplete seal or ineffective seal at the end of the graft. This type of endoleak usually occurs in the early course of treatment, but may also occur later.
Type II endoleak: blood flow into the aneurysm sac due to opposing blood flow from collateral vessels. In some circumstance when there are two or more patent vessels a situation of inflow and outflow develops creating an actively blood flow within channel created within the aneurysm sac.
Type III endoleak: blood flow into the aneurysm sac due to inadequate or ineffective sealing of overlapping graft joints or rupture of the graft fabric. Again, this endoleak usually occur early after treatment, due to technical problems, or later due to device breakdown.
Type IV endoleak: blood flow into the aneurysm sac due to the porosity of the graft fabric, causing blood to pass through from the graft and into the aneurysm sac.