Endoleak and its different types
What is an endoleak? What are the different types of endoleaks, and how are they treated?
An endoleak is persistent blood flow into the aneurysmal sac after placement of a stent graft. A type I endoleak results from poor attachment to the vessel wall. It can be caused by poor apposition of the stent graft to the aortic or iliac wall, often owing to tortuosity, angulation, or disease (e.g., thrombus or calcification). Stent graft undersizing and aortic neck dilation are also causes of type I leaks. Type I leaks are typically treated with balloon dilation or the placement of an additional stent graft or balloon-expandable stent. Type II endoleaks are not caused by the graft itself but rather by retrograde flow into the aneurysm sac from collateral arterial branches such as lumbar arteries or the inferior mesenteric artery. Type II endoleaks sometimes resolve spontaneously or are monitored to see if they contribute to sac expansion or pressurization. If intervention is indicated, they are treated using coils or embolic glues. Type III endoleaks are caused by modular disconnections of stent graft pieces or by graft or metal fatigue causing tears in the fabric. This type of endoleak was more common in the early days of EVAR but is now decreasing in incidence because of more durable designs and more overlap of stent graft pieces in the initial procedure. Type IV endoleaks are transgraft endoleaks caused by fabric porosity or microabrasion caused by graft or metal fatigue. Type III and type IV endoleaks are treated by placement of additional stent graft pieces or through open repair. Type V endoleaks (also called endotension) occur when there is continued aneurysm sac expansion without evidence of a leak site and are poorly understood. Treatment with additional endoluminal components or with open surgical repair may be performed as needed.