Laser Fenestration of Aortic Stent-Grafts Followed by Noncompliant vs Cutting Balloon Dilation: A Scanning Electron Microscopy Study.

PURPOSE: To examine the effects of in situ laser fenestration and subsequent balloon dilation (noncompliant vs cutting) on the graft fabric of 4 aortic stent-graft models. METHOD: In an in vitro setup, the Zenith TX2, Talent, Endurant, and Anaconda aortic stent-grafts (all made of polyester graft material) were subjected to laser fenestration with a 2.3-mm-diameter probe at low and high energy in a physiologic saline solution followed by balloon dilation of the hole. For the first series of tests, 6-mm-diameter noncompliant balloons were used and replaced for the second series by 6-mm-diameter cutting balloons. Each procedure was performed 5 times (5 fenestrations per balloon type). The fenestrations were examined visually and with light and scanning electron microscopy. RESULTS: Each fenestration demonstrated various degrees of fraying and/or tearing regardless of the device. The monofilament twill weave of the Talent endograft tore in the warp direction up to 7.09±0.46 mm at high energy compared with 2.41±0.26 mm for the Endurant multifilament device. The fenestrations of the 3 endografts with multifilament weave (Zenith, Anaconda, and Endurant) showed more fraying; fenestration areas in the multifilament Endurant were >10 mm2 at low and high energy. The fenestrations were free of melted fibers, but minor blackening of the filaments was observed in all devices. Overall, the cutting balloons resulted in worse tearing and damage. Of note, the edges of the dilated laser-formed fenestrations of the Talent and the Endurant grafts demonstrated evidence of additional shredded yarns. CONCLUSION: In situ fenestration does not cause any melting of the polyester; however, the observed structural damage to the fabric construction must be carefully considered. Cutting balloons caused various levels of tearing compared to the noncompliant balloons and cannot be recommended for use in this application. Rather, noncompliant balloons should be employed, but only with endografts constructed from multifilament yarns. The use of in situ fenestration must be restricted to urgent and emergent cases until long-term durability can be determined.

In Vitro Laser Fenestration of Aortic Stent-Grafts: A Qualitative Analysis Under Scanning Electron Microscope.

In situ fenestration of stent-grafts allows patients with life threatening aortic pathologies to be amenable to emergent "off the shelf indications for use" percutaneous treatments as a bail out technique. Three types of aortic stent-grafts were subjected to laser fenestration in a physiological saline solution followed by balloon angioplasty using 8, 10 or 12 mm in diameter noncompliant balloons. The morphology and the size of fenestrations were observed under optical and scanning electron microscopy. The damage to the fabrics was analyzed and quantified. The creation of fenestrations was feasible in all devices, with varying degrees of fraying and/or tearing. The monofilament twill weave (Medtronic Valiant) tore in two directions (warp and weft) while the multifilament weave fenestrations showed more fraying (Anaconda Vascutek and Zenith TX2 Cook). The size and directions of tearing were more predictable with the 8 mm diameter balloon whereas the results obtained with the 10 and 12 mm diameter balloons were more unpredictable. The fenestrations were free of melting of the yarns and blackening of the filaments. The in situ fenestration is feasible but the observed damage to the fabric constructions must be carefully considered. This procedure must currently be limited to urgent and emergent life threatening cases because it is off indications for use for approved devices.