Experimental Model
An ex vivo porcine model was developed using hearts harvested the same day from swine weighing approximately 100kg. Punctures were performed on the interatrial septum using the dedicated RF wire and corresponding generator (RFP-100A, Baylis Medical), or by connecting a 0.014” coronary guidewire (Astato, Asahi Intecc, Aichi, Japan or BMW, Abbott Vascular, Abbott Park, IL) or a standard 0.032” guidewire (Paragon, Integer, Plano, TX) to an electrosurgical generator (ValleyLab, Medtronic, Boulder, CO). Several power settings (20W, 35W and 50W in cut mode) were used in each experiment utilizing electrified guidewires. RF power was manually applied to the proximal end of the guidewire for approximately 2 seconds using an electrocautery pen to represent common clinical use,9, 11, 28 while a predefined 1 second pulse mode setting (approximately 5W) was delivered through the dedicated RF wire (Figure 1). The primary endpoint was the number of RF applications required for TSP. Secondary endpoints included TSP failure rate, TSP consistency, effect of RF power output level, and effect of distance between the tip of the guidewire and the tip of the dilator. Additional qualitative secondary endpoints included tissue puncture collateral damage (e.g. tissue charring, defect size, puncture morphology homogeneity), damage to the TSP guidewire or dilator (e.g. melting, charring and deformation) and the area of tissue heating and peak temperature measured using thermal imaging (FLIR E60, FLIR Systems, Austin, TX).