Intra-operative fenestration of stent grafts: a note of caution based upon preliminary in vitro observations.

Intra-operative fenestrations of stent grafts make more frail and elderly patients amenable to endovascular surgery but require further assessment of the viability of currently used experimental techniques. Four types of polyester fabrics currently employed in stent grafts were exposed in vitro to various protocols of fenestration: cutting, trocaring, and cantering. The resulting fenestrations were examined by gross observation, light microscopy, and scanning electron microscopy. Blunt fenestration by scissors and sharp penetration led to unpredictable apertures, impairment of the integrity of the grafts, and damage to the filaments. The fenestrations were more likely to extend in the woven fabrics, whereas the knitted fabrics were more resistant to fraying. The use of the electric cautery demonstrated the ability to create a fenestration by simultaneously perforating/cutting and edge sealing. Any safe fenestration requires a perforating method that ensures the sealing of the edge of the graft material with a well-controlled diameter. A preoperative fenestration can be tolerated, but there are risks of damage to the stent grafts when reloading the device. More elegant methods of preoperative fenestration, particularly in situ retrograde laser fenestration, are in development and deserve clinical validation.