We present 3 cases of type IIIb endoleak after endovascular aneurysm repair (EVAR) using the Zenith stent graft system. Type III endoleak, like type I endoleak, is a high-pressure, high-risk leak that increases sac pressure up to or even above arterial pressure, and is associated with an increased frequency of open conversions or risk of aneurysm rupture. Type IIIb endoleak is rare but there is much concern that the incidence of type IIIb endoleak is likely to increase hereafter; the mechanism of type IIIb endoleak is deterioration of graft fabric in conjunction with stent sutures. Type IIIb endoleak is difficult to diagnose before rupture. The possibility of type IIIb endoleak should be highly suspected when the continued growth of an excluded aneurysm sac without direct radiologic evidence is observed during follow-up. Type IIIb endoleak can be repaired by relining of the stent graft with additional stent grafts.
Keywords: endoleak; endovascular aneurysm repair; stent graft.