1. POSTER 3 7:24 – 7:31 Safety and feasibility study of a device using guidewire-mediated shock waves to treat chronic total occlusions (CTO) of coronary arteries. Presenter: Marie-Jeanne Bertrand Authors: Marie-Jeanne Bertrand MD M.Sc., Louis-Philippe Riel M.Sc, Steven Dion M.Sc, Pascale Geoffroy M.Sc, Marie-Elaine Clavet-Lanthier, Martin Brouillette ing, Ph.D, Jean-François Tanguay MD

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Genigraphics® has been producing output from PowerPoint® longer than anyone in the industry; dating back to when we helped Microsoft® design the PowerPoint® software. US and Canada: 1-800-790-4001 Email: info@genigraphics.com [This sidebar area does not print.] SAFETY AND FEASIBILITY STUDY OF A DEVICE USING GUIDEWIRE-MEDIATED SHOCK WAVES TO TREAT CHRONIC TOTAL OCCLUSIONS (CTO) OF CORONARY ARTERIES Marie-Jeanne Bertrand, MD MSc 1,2 ; Louis-Philippe Riel MSc 3 ; Steven Dion MSc 3, Pascale Geoffroy MSc 1,2, Marie-Elaine Clavet-Lanthier 2, Martin Brouillette ing. PhD 3, Jean-François Tanguay MD 1,2 1 Université de Montréal, 2 Montreal Heart Institute, 3 Université de Sherbrooke Chronic total occlusions (CTO) are commonly identified in patients with coronary artery disease (CAD), with a prevalence between 20%-30%. These lesions are technically challenging for interventional cardiologists, with a success rate of CTO recanalization that remains between 47% to 72%. A novel technology, which enables to deliver shock waves at the tip of a guidewire, is proposed to cross more easily through calcified and fibrotic CTO lesions. This device could optimize CTO procedure success in symptomatic CAD patients.This study aimed at demonstrating safety and technical performance using a first generation prototype of this technology in an in vivo animal model. BACKGROUND Two prototype versions of a the CTO crossing wire, square and rounded distal tip, were both tested randomly at different levels of energy for 4 minutes and 10 seconds (i.e., 2500 shock wave pulses), with or without wire movement in the coronary artery during energy delivery. The main findings of the in vivo bench testing of the two prototypes CTO guidewires are the following: Figure 2 shows the mean percentage stenosis by QCA for all tested energy levels as a function of Acetylcholine concentration. By QCA, the lumen diameter variations of coronary arteries during IC acetylcholine protocol are found to be similar between all levels of energy applied by the ShockWire (Ach 10 -7 and 10 -6 ), however some numerical differences are observed at Ach dosing 10 -5 and 10 -4. It is found that there is no clear correlation between lumen diameter by QCA and % power (energy) delivered by the ShockWire, owing to the small sample size of this study which limits the statistical power to detect a difference between energy levels. Figure 2 shows the cell viability percentage as a function of applied energy for the two distal tip designs. It is felt that the small sample size of this study is insufficient to draw solid conclusions regarding % CD31 vs. power delivered by CTO guide wire and the impact of guide wire design on vascular injury and endothelial function. All three pigs survived the simulated treatment. The CTO crossing wire was able to deliver energy to the target vessel, was compatible with existing catheters and was radiopaque enough to complete simulated percutaneous interventions. RESULTSDISCUSSION This study demonstrates the acute feasibility of delivering this novel CTO guidewire in coronary arteries in vivo. This promising technology could be a new avenue for interventional cardiologists in treating CTO lesions. CONCLUSIONS Figure 1. Diagram of the CTO guidewire technology MATERIALS & METHODS CTO guidewire technology A 0.014-inch guidewire prototype is connected to a console that generates a large amplitude shock wave at different levels of energy, which is directly transmitted to the distal tip of the guidewire (Figure 1). These early guidewire prototypes comprised a rudimentary radio-opaque marker and did not incorporate a hydrophilic coating in the tip region. Two tip designs were investigated: a square tip and a rounded tip. In vivo protocol for CTO guidewires testing The CTO guidewires were tested in 3 juvenile farm pigs. Both wire tip designs were randomly tested at different output power levels (100%, 75%, 50% and 0%) in different segments of epicardial coronary arteries, while one coronary artery was used as a negative control. Acetylcholine (Ach) was infused at different concentrations (10 -7, 10 -6, 10 -5, 10 -4 mol/l), followed by 100  g nitroglycerin (NTG). Coronary angiography was performed at baseline and after each dose of Ach and NTG, along with QCA diameter (minimal lumen diameter - MLD) measurements. After the procedure, animals were euthanized for histology and immunostaining analysis of vessel endothelium. Figure 2. Mean percentage stenosis by QCA for all energy levels applied by CTO guidewire. Figure 3. Average cell viability, via CD31 immunohistology, as a function of energy level for the two CTO guidewire tip designs. LIMITATIONS The small sample size (N=3) related to this study limits the statistical power to detect a difference between tip shape, power levels, wire movement and vessel wall interactions. This study only evaluated the impact of the early prototypes of CTO guidewire on the endothelium and vascular wall in an acute setting. No commercial CTO guidewire was used as a control to compare the immediate effects on the coronary endothelium. Only two CTO guidewire designs were tested in this small trial. ACKNOWLEDGMENTS Many thanks to Dr M. Brouillette, S. Dion, L-P Riel, and Dr J-F Tanguay for letting me be a part of in this project regarding the development of a novel and innovative technology. This study showed that 100% of energy applied by the CTO guidewire was associated with a complete vasoconstriction of the coronary artery segment at both 10 -5 and 10 -4 mol/l, with macroscopic and microscopic damages of the endothelium. Similar variations of lumen diameter during selective intracoronary infusion of Ach were observed between 0%, 50% and 75% of energy. No clear correlations was found between either the MLD or the percentage of CD31+ and the percentage of energy delivered by the CTO guidewire. Vascular wall damage, endoluminal thrombus and hemorrhage observed in the media could be related to the wire energy, tip characteristics and/or guidewire movements.