POSTER 37:24 – 7:31
Safety and feasibility study of a device using guidewire-mediated shockwaves 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, PascaleGeoffroy M.Sc, Marie-Elaine Clavet-Lanthier, Martin Brouillette ing, Ph.D, Jean-François Tanguay MD
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SAFETY AND FEASIBILITY STUDY OF A DEVICE USING GUIDEWIRE-MEDIATED SHOCK WAVES TO TREAT CHRONICTOTAL OCCLUSIONS (CTO) OF CORONARY ARTERIES
Marie-Jeanne Bertrand, MD MSc1,2; Louis-Philippe Riel MSc3; Steven Dion MSc3, Pascale Geoffroy MSc1,2, Marie-Elaine Clavet-Lanthier2, Martin Brouillette ing. PhD3, Jean-François Tanguay MD1,2
1Université de Montréal, 2Montreal Heart Institute, 3Université de Sherbrooke
Chronic total occlusions (CTO) are commonly identified inpatients with coronary artery disease (CAD), with a prevalencebetween 20%-30%. These lesions are technically challengingfor interventional cardiologists, with a success rate of CTOrecanalization that remains between 47% to 72%.
A novel technology, which enables to deliver shock waves atthe tip of a guidewire, is proposed to cross more easily throughcalcified and fibrotic CTO lesions. This device could optimizeCTO procedure success in symptomatic CAD patients.Thisstudy aimed at demonstrating safety and technicalperformance using a first generation prototype of thistechnology 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 ofenergy for 4 minutes and 10 seconds (i.e., 2500 shock wave pulses), with or without wire movement in the coronary artery duringenergy 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. ByQCA, the lumen diameter variations of coronary arteries during IC acetylcholine protocol are found to be similar between all levelsof energy applied by the ShockWire (Ach 10-7 and 10-6), however some numerical differences are observed at Ach dosing 10-5 and10-4. It is found that there is no clear correlation between lumen diameter by QCA and % power (energy) delivered by theShockWire, owing to the small sample size of this study which limits the statistical power to detect a difference between energylevels.
•Figure 2 shows the cell viability percentage as a function of applied energy for the two distal tip designs. It is felt that the smallsample size of this study is insufficient to draw solid conclusions regarding % CD31 vs. power delivered by CTO guide wire and theimpact 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 radiopaqueenough to complete simulated percutaneous interventions.
RESULTS
DISCUSSION
This study demonstrates the acute feasibility of delivering thisnovel CTO guidewire in coronary arteries in vivo.
This promising technology could be a new avenue forinterventional 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 consolethat generates a large amplitude shock wave at different levelsof energy, which is directly transmitted to the distal tip of theguidewire (Figure 1). These early guidewire prototypescomprised a rudimentary radio-opaque marker and did notincorporate a hydrophilic coating in the tip region. Two tipdesigns 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. Bothwire tip designs were randomly tested at different outputpower levels (100%, 75%, 50% and 0%) in different segments ofepicardial coronary arteries, while one coronary artery wasused as a negative control. Acetylcholine (Ach) was infused atdifferent concentrations (10-7, 10-6, 10-5, 10-4 mol/l), followedby 100 g nitroglycerin (NTG). Coronary angiography wasperformed at baseline and after each dose of Ach and NTG,along with QCA diameter (minimal lumen diameter - MLD)measurements. After the procedure, animals were euthanizedfor histology and immunostaining analysis of vesselendothelium.
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 thestatistical 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 ofCTO guidewire on the endothelium and vascular wall in anacute setting.
No commercial CTO guidewire was used as a control tocompare 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-FTanguay for letting me be a part of in this project regarding thedevelopment of a novel and innovative technology.
This study showed that 100% of energy applied by the CTOguidewire was associated with a complete vasoconstriction ofthe coronary artery segment at both 10-5 and 10-4 mol/l, withmacroscopic and microscopic damages of the endothelium.
Similar variations of lumen diameter during selectiveintracoronary infusion of Ach were observed between 0%, 50%and 75% of energy.
No clear correlations was found between either the MLD orthe percentage of CD31+ and the percentage of energydelivered by the CTO guidewire.
Vascular wall damage, endoluminal thrombus and hemorrhageobserved in the media could be related to the wire energy, tipcharacteristics and/or guidewire movements.
