Experimental Analysis of the Quality of Needle-Assisted Fenestration in Aortic Stent-Grafts and the Differences Between Gradual and Rapid Balloon Dilation

Abstract

Purpose: To report the findings of an in vitro experiment to evaluate the quality of needle fenestrations dilated by different size balloons in various stent-grafts and to investigate the differences between gradual and rapid dilation. Materials and Methods: Fenestrations were made using an 18-G needle in 5 different polyester or expanded polytetrafluoroethylene (ePTFE) stent-grafts: Relay, Valiant, Hercules, TAG, and Ankura. Each stent-graft received 2 groups of fenestrations: one was followed by gradual sequential dilation (4-, 6-, 8-, and 10-mm balloons) and the other by rapid dilation (4- and 10-mm balloons). The pressure was increased to 10 atmospheres or until the balloon was fully inflated with no waist. Quantitative and qualitative evaluations, including fenestration diameter, area, shape, and margins were conducted using light microscopy and scanning electron microscopy. Results: Relay had the strongest resistance to dilation and Ankura the slightest. The maximum length and area of holes expanded as the balloon diameter increased. The fenestrations in polyester devices were mostly elliptical or slit-like, with limited tears but extensive fibers visible in the margin, while ePTFE stent-grafts showed larger fenestration areas with clearer margins. Ankura showed the best quality of fenestrations, which were always circular or square without fabric tears, while the holes in the TAG were square or elliptical but sometimes had a slit after large balloon dilation (≥6 mm). The Relay, Valiant, Hercules, and Ankura devices showed no difference in maximum diameter, fenestration area, or scores of shape and margin (p>0.05). Rapid dilation in the TAG increased the rate of uncontrolled fabric tear, resulting in a larger final diameter (12.90 vs 10.82 mm, p=0.047), smaller area (30.46 vs 41.09 mm2, p=0.028), worse shape (0.75 vs 1.20, p=0.268), and worse margin (0.40 vs 1.00, p=0.174). Though the decreased fenestration shape and margin scores did not reach statistical significance, the trend for decline was more obvious than with the other devices. Conclusion: Materials and structures of the stent-grafts determine the quality of fenestrations dilated by different size balloons. The use of sequential vs rapid balloon dilation is also crucial for fashioning high-quality fenestrations and should be selected judiciously.

Midterm Results of Retrograde In Situ Needle Fenestration During Thoracic Endovascular Aortic Repair of Aortic Arch Pathologies

“…[8][9][10][11][12] Besides, ISNF can be used to treat various aortic arch pathologies, even in challenging cases when the proximal lesions are very close to the branch arteries. According to our experience and others, 14,20 ePTFE is considered the better choice for ISNF than polyester, although there are no long-term durability data. The anatomies of both the aortic arch and the aortic branches are not changed after ISNF-assisted TEVAR, and as a result, blood flow is physiological.…”

Optimal In Situ Fenestration Technique With Laser Perforation and Balloon Dilation for Aortic Stent-Grafts

“…There are various methods for retrograde fenestration, which include needle, 19,20 radiofrequency, 7,21 or laser. 22 Currently, there is limited evidence to support the choice of one technique over another.…”

Commentary: Honing the Technique of In Situ Stent-Graft Fenestration

“…18 The theoretical advantage of an energy-based method might be jeopardized by fraying of the polyester fabrics caused by balloon dilation. This was particularly evident in the Li experiments 11 when large size balloons (>Ø 10 mm) were used. In benchtop and animal studies by some experienced teams, 3 cutting balloons have been shown to cause major tearing.…”

“…In the December 2020 issue of the JEVT , Li et al 11 must be congratulated for presenting a major step in the analysis of stent-graft fenestrations. They selected a broad variety of stent-grafts composed of ePTFE or Dacron from which they formulated recommendations for the optimal technique of balloon dilation.…”