A comparison between standard and high density Resilient AneuRx in reducing aneurysm sac pressure in a chronic canine model.

OBJECTIVES: Low intra-aneurysm sac pressure has been shown to correlate with sac shrinkage following endovascular aneurysm repair (EVAR) whereas high pressure results in sac enlargement. The Resilient AneuRx (RSA) has higher density Dacron compared with the standard AneuRx (STA) and was developed in an attempt to reduce type 4 and 5 endoleaks, thereby more effectively reducing sac pressure. The purpose of this study is to compare the ability of RSA and STA in reducing sac pressure in a chronic canine aneurysm model.

MATERIALS AND METHODS: Artificial polytetrafluoroethylene (PTFE) aneurysm (26 x 50 mm) with an Endosure wireless pressure sensor (CardioMEMS, Atlanta, Ga) attached to the inner surface was implanted in the abdominal aorta of 10 mongrel dogs. Two weeks after creation of the aneurysm, each animal underwent EVAR with either STA (n = 5) or RSA (n = 5). Following EVAR, intra-sac pressure was measured with the implanted wireless pressure sensor up to 3 months postoperatively when the animals were sacrificed.

RESULTS: EVAR was successful with no signs of an endoleak in all 10 dogs. Pressure sensing with the wireless sensor was also successful in each animal until the end of the study. Systolic intra-sac pressure remained at a high level in the STA group, whereas it gradually lowered over time in the RSA group. This difference reached statistical significance at 2 months and lasted to 3 months. No endoleak was detected in either group at the time of sacrifice. Gross analysis confirmed that all the aneurysm sacs were thrombosed without any flow inside the sac.

CONCLUSION: Despite absence of an endoleak, intra-sac pressure remained high in the STA group. RSA effectively reduced sac pressure over time. Graft porosity appears to be an important factor that may determine the outcome of EVAR. These findings may be useful in designing improved endograft.