Transprosthetic Fenestration With Electrified Wires. Experimental Evaluation of Three Multifilament Endografts.

Purpose: In situ fenestration of aortic endografts is an alternative endovascular technique for treatment of complex aortic aneurysms. While this technique has been carried out also to pass stent-grafts in individual cases, its feasibility and safety using different stent-grafts needs to be evaluated.

Methods: In a saline bath at water temperature of 37°C, a 0.018" Astato 30 guidewire was advanced through 3 different stent-grafts (RelayPro, Zenith and Endurant II) by applying external current of 180 W via an electrosurgery pencil. Puncture efficacy and quality of the fenestration after ballooning with a 6 mm percutaneous transluminal angioplasty (PTA) catheter were assessed. Then, balloon-expandable covered stents were deployed in the fenestrations and evaluated for stenosis, using microscopy and radiography.

Results: Crossing of the electrified guidewire was instantaneous in the Zenith (n:10) and RelayPro (n:10) groups but not in 3 of 10 punctures in the Endurant group (p<.05). The fenestration area created after PTA was significantly larger in the RelayPro (5.3 mm ± 1.8, interquartile range [IQR] 1.6) and Zenith group (6.7 mm ± 0.7, IQR 0.5) compared to Endurant (2.3 mm ± 0.4, IQR 0.5, p<.001). Fraying was observed in all groups while graft shredding was found in 8 cases after PTA of the Zenith and Endurant endografts and in 5 of the RelayPro group, but the difference was not significant. Vertical tearing was detected after RelayPro (2 out of 10) and Zenith (6 out of 10) fenestrations, no damage was found in the Endurant group (p<.01). Residual stenosis at the level of the fenestration after implantation of a 6 × 79 mm VBX stent had to be corrected in all Endurant cases with a high-pressure PTA catheter. No stenosis was found in the RelayPro and Zenith groups before and after flaring.

Conclusions: The "electrified wire" technique is a feasible tool that can be used to perform in situ fenestration by perforation of the endograft fabric. Based on this experimental evaluation the "ideal graft" for this technique could not be identified. Long-term fatigue tests and comparison with other fenestration techniques are required.

Clinical Impact: In situ endograft fenestration can be a useful technique in emergent aortic repair. Recently, the electrified wire technique has been proposed as alternative option to laser, radiofrequency and needle-based techniques. In comparison to these methods, the use of electrified wires can be performed without modifications of routine equipment. Additionally, the material costs can be substantially reduced. However, the effectiveness of this approach for fenestration of different prosthetic grafts is unknown. Based on our experimental studies, the electrified wire technique is feasible but the Endurant endograft requires more attempts, and the placement of a bridging stent should be completed with high-pressure balloons.