ABSTRACT
Endovascular repair of abdominal aortic aneurysms (AAAs) is rapidly becoming an accepted alternative to conventional open surgical procedures, especially for high-risk patients (1–3). Despite the decreased invasiveness of the endovascular technique, numerous unique complications occurred with this new approach that were never considered an issue in conventional surgery. First and foremost among these complications was endoleak, defined as the presence of intra-aneurysm flow around an endovascular graft (4). This flow produces an increase in the pressure inside the aneurysmal sac that potentially maintains aneurysm expansion and eventually results in rupture. Although the causes of endoleak are many, any exposure of the residual aneurysm sac to arterial flow represents a potential persistent pressurization of the aneurysm and the consequent potential risk of rupture. However, the natural history of endoleaks remains poorly defined. If no endoleak is present, then the aneurysm should be maximally protected and risk of expansion or rupture minimized. Despite this concern, in some patients with endoleaks the aneurysm continues to shrink even with residual blood flow, conversely, although very rarely, aneurysms are seen to grow even in the absence of any 92detectable endoleak; in this latter situation the condition is named endotension or pressure endoleak. Nevertheless, the exact hemodynamic forces applied to the aneurysm sac, independent of the presence or absence of endoleak, remain poorly defined.
