Commentary: “Aneurysm Sac Pressure after EVAR”

Abstract

EVAR aims at excluding the aneurysm sac from blood flow and systemic pressure. It is surprising the relatively little knowledge gathered on intra-aneurysm sac pressure after EVAR, especially taking into account that EVAR has been introduced 16 years ago. The review done by Hinnen and coworkers on this important subject is therefore greatly appreciated. It is widely accepted that reduced intra-sac pressure after EVAR may decrease wall tension and thereby make the aneurysm shrink. However, as the review article by Hinnen and coworkers points out, experimental studies have shown that intra-aneurysm pressure is influenced by multiple factors such as the mechanical properties of the aneurysm wall, the type of graft and the aneurysm size. The measurement of intra-aneurysm sac pressure after EVAR has to address two main issues: the access to the AAA and the use of a pressure sensor that does not loose its reliability within thrombus. Mean pressure index (MPI) and pulse pressure have been the most commonly used parameters in the evaluation of intraaneurysm pressure. Successful EVAR, defined by shrinkage of the AAA in the absence of endoleak, has been repeatedly associated with low MPI and pulse pressure. However, there is also data to support that the reduction of MPI does not occur immediately after EVAR. It may take at least 1 month for the pressure to drop after stent-graft insertion. Furthermore, aneurysm expansion without endoleaks (endotension or type V endoleaks) is usually associated with elevated intra-sac pressure. Our own studies suggest