Intermittent, posture-dependent, and late endoleaks after endovascular aortic aneurysm repair.

In this article we present our experience with the concept of the unstable aortic sac after endovascular aortic aneurysm repair. The improvements in ultrasound technology and features suggestive of sac instability are described. Patients with this condition are usually considered to have endotension, in which the aortic sac undergoes progressive enlargement in the absence of any demonstrable endoleak. We have found, however that approximately one third of these patients have intermittent or posture-dependent endoleaks. The secondary ultrasound manoeuvres that enable these endoleaks to be diagnosed are described. An awareness of the potential presence of these endoleaks may avoid unnecessary conversion to open repair or late rupture.