Effect of Different EndoAnchor Configurations on Aortic Endograft Displacement Resistance: An Experimental Study

Abstract

Purpose: This study investigated the effect of different EndoAnchor configurations on aortic endograft displacement resistance in an in vitro model. Materials and Methods: An in vitro model was developed and validated to perform displacement force measurements on different EndoAnchor configurations within an endograft and silicone tube. Five EndoAnchor configurations were created: (1) 6 circumferentially deployed EndoAnchors, (2) 5 EndoAnchors within 120° of the circumference and 1 additional, contralateral EndoAnchor, (3) 4 circumferentially deployed EndoAnchors, (4) 2 rows of 4 circumferentially deployed EndoAnchors, and (5) a configuration of 2 columns of 3 EndoAnchors. An experienced vascular surgeon deployed EndoAnchors under C-arm guidance at the proximal sealing zone of the endograft. A constant force with increments of 1 newton (N) was applied to the distal end of the endograft. The force necessary to displace a part of the endograft by 3 mm was defined as the endograft displacement force (EDF). Two video cameras recorded the measurements. Videos were examined to determine the exact moment 3-mm migration had occurred at part of the endograft. Five measurements were performed after each deployed EndoAnchor for each configuration. Measurements are given as the median and interquartile range (IQR) Q1, Q3. Results: Baseline displacement force measurement of the endograft without EndoAnchors resulted in a median EDF of 5.1 N (IQR 4.8, 5.2). The circumferential distribution of 6 EndoAnchors resulted in a median EDF of 53.7 N (IQR 49.0, 59.0), whereas configurations 2 through 5 demonstrated substantially lower EDFs of 29.0 N (IQR 28.5, 30.1), 24.6 N (IQR 21.9, 27.2), 36.7 N, and 9.6 N (IQR 9.4, 10.0), respectively. Decreasing the distance between the EndoAnchors over the circumference of the endograft increased the displacement resistance. Conclusion: This in vitro study demonstrates the influence EndoAnchor configurations have on the displacement resistance of an aortic endograft. Parts of the endograft where no EndoAnchor has been deployed remain sensitive to migration. In the current model, the only configuration that rivaled a hand-sewn anastomosis was the one with 6 EndoAnchors. A circumferential distribution of EndoAnchors with small distances between EndoAnchors should be pursued, if possible. This study provides a quantification of different EndoAnchor configurations that clinicians may have to adopt in clinical practice, which can help them make a measured decision on where to deploy EndoAnchors to ensure good endograft fixation.

Evaluation of EndoAnchor Aortic Wall Penetration After Thoracic Endovascular Aortic Repair

“…16 The only surrogate evidence is from experiments suggesting that higher numbers (n=6) deployed circumferentially are better. 17…”

“…The Heli-FX EndoAnchor system delivers small helical "screws" that attach the endograft to the aorta to obtain secure transmural fixation that replicates the pullout force of a surgical anastomosis. 16,17 The thoracic iteration of the Heli-FX system (18-F, 90-cm working length) comes in 3 lengths of deflected tip reach (22, 32, and 42 mm). Each disposable system is for single use only, costing approximately €4760 (£4200).…”

In Search of the Optimal Endosutured Aneurysm Repair

“…We read with great interest the article by Goudeketting et al, 1 in which the authors demonstrate in vitro that not only the configuration but also the distribution of EndoAnchors (Medtronic Vascular, Santa Rosa, CA, USA) is relevant to avoiding displacement of the endograft's proximal end, with ensuing loss of seal. Overall, the experimental setup is elegantly described, and the main limitations have been correctly addressed, importantly, the lack of active fixation barbs (either suprarenal or infrarenal) on the truncated Valiant endograft used in the models.…”

“…This would create a hybrid combination that can be appreciated from the positions in figure 5. 1 Using 8 EndoAnchors would also address the more utilitarian aspect of maximizing cassette usage.…”

“…Nevertheless, studies such as those by Goudeketting et al 1 are extremely necessary. The important study by Melas et al, 9 suggesting a minimum of 4 EndoAnchors in necks up to 28 mm and ≥6 when dealing with ≥29-mm necks has been employed as the biomechanical default in endosutured aneurysm repair (ESAR).…”