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).