Not All Endografts Created Equal with Regard to Inflammatory Response


While endografts used in the repair of abdominal aortic aneurysm are known to induce early low-level inflammation, certain types appear to evoke a stronger response than others, according to results of a small nonrandomized study published online January 11, 2013, ahead of print in the Journal of Vascular Surgery. However, this variation does not translate into differences in perioperative complications or affect the generally benign course of the inflammation.

Researchers led by Konstantinos G. Moulakakis, MD, MSc, of the University of Athens (Athens, Greece), looked at 87 patients who underwent elective endovascular aortic repair of asymptomatic infrarenal AAAs. Patients received 1 of 4 types of endograft:

  • Anaconda (Sulzer Vascutek, Bad Soden, Germany; n = 28)
  • Zenith (Cook Medical, Bloomington, IN; n = 26)
  • Excluder (WL Gore, Flagstaff, AZ; n = 23)
  • Endurant (Medtronic, Minneapolis, MN; n = 10)

All 4 groups had similar baseline characteristics including atherosclerotic risk factors and baseline serum levels of cytokines. Nor did they differ in the type of anesthesia used, operative time, contrast volume, or mean volume of blood lost during surgery.

Endograft procedures were successful in all patients, with no conversions to open surgery, deaths, or major perioperative complications. Additionally, there was no postoperative increase in troponin levels. At 1-month follow-up, the groups did not differ in rates of endoleak.

Differences in Inflammatory Markers

In all groups, serum levels of cytokines IL-6 and IL-10 were significantly elevated at 24 and 48 hours postoperatively compared with preoperative levels. The Anaconda group had the highest mean value of IL-10 at 24 hours, differing significantly from the Excluder (P < 0.001) and Endurant (P = 0.04) groups. The Zenith group had higher mean values only in comparison with Excluder (P = 0.01). At 48 hours, mean cytokine values in patients treated with Anaconda and Zenith were higher in comparison with both Endurant and Excluder. With regard to IL-6, the Anaconda group had the highest mean values at 24 hours of all 4 groups.

At 48 hours, patients treated with Anaconda had higher mean temperatures compared with the Excluder (P = 0.03) and Zenith (P = 0.02).

Higher mean white blood cell counts were recorded after 24 hours in patients treated with the Anaconda compared with the Excluder (P < 0.001) and Zenith (P < 0.001), and in Endurant-treated patients compared with the Excluder (P = 0.001) and Zenith (P = 0.01).

No interaction was seen between the amount of clot in the AAA before repair and any marker of postimplantation inflammation.

Materials, Insertion Technique May Play Role

The authors say the milder reaction evoked by the Excluder, which is consistent with results of an earlier series, may be due to a number of factors including material composition. The Excluder is made from expanded polytetrafluoroethylene, whereas the other 3 grafts consist of woven polyester. According to the investigators, variations in graft material have been suggested as an explanation for different early biologic responses between open and endovascular aneurysm repair. Another important issue relates to the insertion technique of the delivery system. Unlike the other 3 endografts, the Excluder is inserted through an introducer sheath.

“Although there are no significant differences in introducer system size, we can assume that the insertion of a sheath, which is softer and more flexible than the entire stent graft, may cause less injury to the vascular endothelium,” Dr. Moulakakis and colleagues write.

Yet another explanation may lie in the manufacturing process since “[t]hickness and porosity may differ between woven polyester endografts,” while “the presence of a metallic skeleton with different configuration and the use of different constructive materials to build sheaths, main body, and iliac limbs probably have a role and [help explain] variability in inflammatory reaction after EVAR,” they add.

Study Details

Temperature, white blood cell count, platelet count, and serum concentrations of cytokines were measured preoperatively and 24 hours and 48 hours postoperatively. Almost one-third of patients were receiving statins on admission. No postoperative anti-inflammatory drugs were administered.

 


Source:
Moulakakis KG, Alepaki M, Sfyroeras GS, et al. The impact of endograft type on inflammatory response after endovascular treatment of abdominal aortic aneurysm. J Vasc Surg. 2013;Epub ahead of print.

 

 

Related Stories:

Disclosures
  • Dr. Moulakakis reports no relevant conflicts of interest.

Comments