The effect of injectable biocompatible elastomer (PDMS) on the strength of the proximal fixation of endovascular aneurysm repair grafts: An in vitro study

Purpose: One of the major concerns in the long-term success of endovascular aneurysm repair (EVAR) is stent graft migration, which can cause type I endoleak and even aneurysm rupture. Fixation depends on the mechanical forces between the graft and both the aortic neck and the blood flow. Therefore, there are anatomical restrictions for EVAR, such as short and angulated necks. To improve the fixation of EVAR grafts, elastomer (PDMS) can be injected in the aneurysm sac. The support given by the elastomer might prevent dislocation and migration of the graft. The aim of this study was to measure the influence of an injectable biocompatible elastomer on the fixation strength of different EVAR grafts in an in vitro model. Methods: The proximal part of three different stent grafts was inserted in a bovine artery with an attached latex aneurysm. The graft was connected to a tensile testing machine, applying force to the proximal fixation, while the artery with the aneurysm was fixated to the setup. The force to obtain graft dislodgement (DF) from the aorta was recorded in Newtons (N). Three different proximal seal lengths (5, 10, and 15 mm) were evaluated. The experiments were repeated after the space between the graft and the latex aneurysm was filled with the elastomer. Independent sample nests were used for the comparison between the DF before and after elastomer treatment for each seal length. Results: The mean DF (mean +/- SD) of all grafts without elastomer sac filling for a proximal seal length of 5, 10, and 15 mm were respectively, 4.4 +/- 3.1 N, 12.2 +/- 10.6 N, and 15.1 +/- 6.9 N. After elastomer sac filling, the dislodgement forces increased significantly (P < .001) to 20.9 +/- 3.8 N, 31.8 +/- 9.8 N, and 36.0 +/- 14.1 N, respectively. Conclusions: The present study shows that aneurysm sac filling may have a role as an adjuvant procedure to the present EVAR technique. The strength of the proximal fixation of three different stent grafts increases significantly in this in vitro setting. Further in vivo research must be done to see if this could facilitate the treatment of aneurysms with short infrarenal necks. (J Vase Surg 2010;52:152-8.)