Type IIIb endoleak and relining : a mathematical model of distraction forces

Swaelens, C; Poole, R; Torella, F; McWilliams, R; England, A; Fisher, R

Abstract

Purpose: To examine the changes in distraction force following relining of a conventional abdominal aortic stent-graft with a type IIIb endoleak using the Nellix endovascular sealing device compared to a unilateral stent-graft.
Methods: Relining is often used to repair type IIIb endoleaks, but the consequences to graft stability are unknown. A mathematical model was constructed based on pressure and volume flow through the stent-grafts, incorporating recognized distraction force equations. Steady flow was presumed at peak systolic pressures to calculate the maximum distraction force, with gravity ignored. Distraction forces for 28- to 36-mm-diameter stent-graft bodies with 16-mm limbs were calculated and compared to forces following relining with single and double Nellix devices or the Renu unilateral device.
Results: Distraction forces for the 28-, 32-, and 36-mm stent-grafts prior to relining were 5.99, 10.21, and 14.99 N, respectively. Similar forces were reported after relining with bilateral Nellix devices (5.86, 10.08, and 14.86 N, respectively). However, use of a unilateral Nellix increased the distraction forces to 9.92, 14.14, and 18.92 N, respectively. These were comparable to the increase observed after relining with a Renu unilateral stent-graft (9.87, 14.09, and 18.86 N, respectively). The proportional increase in distraction force for a unilateral relining ranged from 26% to 66%, with the greatest increase noted in the smaller diameter main bodies.
Conclusion: Relining a stent-graft with a type IIIb endoleak using bilateral Nellix devices does not increase the distraction force. However, a unilateral Nellix device or the Renu system could theoretically increase the distraction force by up to 66%, potentially risking migration and type Ia endoleak. In clinical practice, these results suggest that a relining with bilateral Nellix may have benefits over the Renu unilateral stent-graft.

Citation

Swaelens, C., Poole, R., Torella, F., McWilliams, R., England, A., & Fisher, R. (2016). Type IIIb endoleak and relining : a mathematical model of distraction forces. Journal of Endovascular Therapy, 23(2), 297-301. https://doi.org/10.1177/1526602816631106

• Journal Article Type: Article
• Online Publication Date: Feb 11, 2016
• Publication Date: Apr 1, 2016
• Deposit Date: Jan 25, 2016
• Publicly Available Date: Apr 25, 2016
• Journal: Journal of Endovascular Therapy
• Print ISSN: 1526-6028
• Electronic ISSN: 1545-1550
• Publisher: SAGE Publications
• Volume: 23
• Issue: 2
• Pages: 297-301
• DOI: https://doi.org/10.1177/1526602816631106
• Publisher URL: http://dx.doi.org/10.1177/1526602816631106
• Related Public URLs: http://jet.sagepub.com/