Preserving the integrity of oesophageal stents with laser therapy and argon plasma coagulation: An in vitro study

Thermal lasers and argon plasma coagulation are widely used in the treatmen t of stent overgrowth in patients with advanced oesophageal malignancy. The aim of treatment is to achieve patency while avoiding damage to the prosth esis. This experimental study was designed to determine the power and durat ion of application that can be safely tolerated by four different types of oesophageal prostheses. Five stents were studied: wall stent; open metal me sh stent (uncovered Ultraflex); covered metal mesh stent (covered Ultraflex ); Gianturco (Z-stent); Esophagocoil. Nd-YAG Laser, GaAlAs diode laser and argon plasma coagulation were applied in non-contact mode at gradually incr easing power levels and duration and the effects were observed. The use of argon plasma coagulation on Esophagocoil stent seems safe in power settings of 100 W up to 10 s. The diode laser is intermediate in that Gianturco and Esophagocoil stents can withstand pulses of up to 50 VV for about 2 s. The Nd-YAG laser is detrimental to most stents at power levels of 20 W. Only t he Esophagocoil withstands Nd-YAG pulses of 60 W but only up to Is. Wallste nt, open and membrane-covered mesh stents perform poorly in that they can o nly tolerate up to 1.5 s of power at 25 W with the Diode and 1.0 s of power at 20 W with Nd-YAG laser. The use of different thermal modalities on the five stents has indicated safe power limits and duration. Membrane-covered stents are always damaged by thermal laser application unless the membrane is truly transparent.