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LAMPOON is a technique we developed directing radiofrequency (RF) energy through a coronary guidewire to lacerate the anterior mitral leaflet to prevent outflow obstruction during transcatheter mitral valve replacement. Tissue laceration requires concentration of RF energy at the guidewire-tissue interface without dispersal through low impedance blood.
LAMPOON was performed successfully in swine and humans. Simultaneously, guidewire electrosurgery was optimized in ex vivo swine aorta in 0.9% sodium chloride bath. Transmural lacerations were made using an unmodified guidewire loop (Confianza pro-12, Asahi-Intecc) and guidewires focally denuded with a scalpel at the tissue interface, either circumferentially or partially along the inner curvature. Wires were sheathed in 6Fr coronary catheters and pulled at constant 5N force (ZP-11, Imada) and 30W charge (Valleylab Force FX, Medtronic) for 2 secs. All wires were tested with and without an insulating polymer jacket (Piggyback Wire Convertor 145cm, Vascular Solutions) on the afferent wire limb, and with and without a 5% dextrose infusion through the catheters.
Wires without denudation or complete circumferential denudation did not lacerate aorta under any condition. Smooth, linear lacerations were seen with wires denuded only at the inner curvature. A glucose infusion significantly increased the length of the laceration, whereas a polymer jacket made no significant difference [Fig. 1].
Partial denudation focuses RF energy at the target site for effective heating. A constant flush of non-ionic liquid displaces blood from the electrosurgery site, directing current through the tissue of interest. This also prevents char and coagulum formation. These principles can be applied broadly to catheter electrosurgery in structural intervention.