Initial results of a first-in-human study on the PlasmaWire TM System, a new radiofrequency wire for recanalization of chronic total occlusions

Transcription

1 Received: 24 January 2017 Revised: 1 August 2017 Accepted: 20 August 2017 DOI: /ccd ORIGINAL STUDIES Initial results of a first-in-human study on the PlasmaWire TM System, a new radiofrequency wire for recanalization of chronic total occlusions Daitaro Kanno, MD 1 Etsuo Tsuchikane, MD, PhD 2 Kenya Nasu, MD 2 Osamu Katoh, MD 3 Yoshifumi Kashima, MD 1 Umihiko Kaneko, MD 1 Tsutomu Fujita, MD 1 Yoriyasu Suzuki, MD 4 Takahiko Suzuki, MD 2 1 Department of Cardiovascular Medicine, Sapporo Cardio Vascular Clinic, Sapporo, Japan 2 Department of Cardiovascular Medicine, Toyohashi Heart Center, Toyohashi, Aichi, Japan 3 RetroVascular Inc, Pleasanton, California 4 Department of Cardiovascular Medicine, Nagoya Heart Center, Nagoya, Aichi, Japan Correspondence Daitaro Kanno, MD, North 49, East 16, 8-1, Higashi Ward, Sapporo, Hokkaido, , Japan. d.kanno@scvc.jp Abstract Objectives: To examine the safety, efficacy, and efficiency of the PlasmaWire TM System to recanalize coronary chronic total occlusions (CTO) using controlled ablation inside the CTO. Background: The PlasmaWire TM System is a new bipolar radiofrequency (RF) wire system utilizing plasma-mediated ablation to facilitate wire crossing in CTOs. Two independent PlasmaWire TM wires are used in tandem for channel creation by applying RF energy between the tips so as to localize the ablation. Methods: Prospective, nonrandomized, single-arm, multicenter study in seven patients with CTOs indicated for percutaneous coronary intervention (PCI). Results: In this study, both wires were antegradely delivered to the distal end of CTO for antegrade re-entry in two cases and bidirectionally (antegrade and retrograde) delivered to the CTO for retrograde re-entry in five cases. In all cases, channel creation was achieved within a few seconds and was confirmed on angiogram or intravascular ultrasound (IVUS) and CTO recanalization was successfully achieved without any major adverse cardiac and cerebrovascular events (MACCE) or other minor complications. The clinical follow-up showed no clinical event at 1 month. Conclusions: The PlasmaWire TM System was shown to be safe and effective in obtaining CTO recanalization through a re-entry channel utilizing plasma-mediated ablation while reducing procedure time. The PlasmaWire TM System is a new bi-polar RF wire system utilizing plasma-mediated ablation for channel creation to facilitate CTO recanalization. This first-in-human study in which seven patients were enrolled was conducted to demonstrate the safety, efficacy, and efficiency of this system for CTO recanalization. Channels through the CTOs were successfully created within a few seconds by applying RF energy between the tips of two independent PlasmaWire TM wires and recanalization was achieved in all cases without any complication. The PlasmaWire TM System may safely facilitate CTO recanalization with less vessel injury and improve initial results of CTO PCI while reducing procedure time. KEYWORDS ablation, catheter/cryoblation/rf, coronary artery disease, new devices (in general), percutaneous coronary intervention Catheter Cardiovasc Interv. 2018;91: wileyonlinelibrary.com/journal/ccd VC 2017 Wiley Periodicals, Inc. 1045

2 1046 KANNO ET AL. 1 INTRODUCTION Although increasing operator experience, refined devices, and the emergence of new techniques have improved the success rate of PCI of CTO [1 6], no new CTO devices have been proven to significantly improve the success rate of CTO PCI as compared to mechanical CTO wires. Radiofrequency (RF) wires have been studied for around 30 years [7] and some have been commercially available primarily for coronary and/or peripheral use (Safe-Cross TM Wire, Intraluminal Therapeutics [8,9], San Diego, California; PowerWire TM, Baylis Medical Company [10], Montreal, Canada), however, these wires relied on a monopolar approach, requiring an external electrode for their return path, thereby limiting their ability to instantaneously create channels without causing thermal damage and to localize the ablated area. Recently, a novel bipolar RF wire system, PlasmaWire TM System (RetroVascular, Pleasanton, CA), was developed which creates a plasma to facilitate plaque ablation and creates a channel inside a CTO (by localized and directional plasma between the coupled RF wire tips), with minimal thermal injury. This is a first report on the initial results of the first-in-human (FIH) study of the PlasmaWire TM System applied for treatment of coronary CTOs. 2 METHODS 2.1 Study design and population The study was a prospective, nonrandomized, single-arm, multicenter study. Among patients with coronary CTOs listed as a clinical candidate for PCI in three hospitals, patients in who wire crossing failed despite a 10-min attempt with conventional mechanical wires and in which the CTO exit was still visible on angiogram after the failed attempt, were eligible for the study. The inclusion criteria were as follows: eligible for stenting or CABG, TIMI flow 0, occlusion duration >3 months or unknown, reference vessel diameter >2.5 mm (visual), total occlusion length >10 mm or no excessive bend (>908) proximal to CTO. The exclusion criteria were as follows: contraindication for use of heparin, intolerance to dual antiplatelet therapy, abnormal CPK elevation or acute myocardial infarction (AMI), bleeding disorders, major bleeding or stroke within 6 months, deep-vein thrombosis, LVEF < 30%, coronary aneurysm adjacent to targeted CTO or other life-threatening disease. The study protocol was approved by the ethics committee of the three hospitals and all patients signed informed consent before the procedure. 2.2 Device description and technical details of use The PlasmaWire TM System consists of three primary components: (1) PlasmaWire TM, (2) RF Generator (RFG), and (3) Connector Cable. The in. PlasmaWire TM has a polymer insulation along its entire 190- cm length and an exposed distal tip (Figure 1A) and proximal end. The wire structure is innovatively designed as a CTO wire (tip load: 3.0 g) to perform and handle similar to Gaia 2nd wire (Asahi Intecc, Nagoya, Japan) by incorporating a novel rope coil technology. The custom RFG (Figure 1B) was connected to a laptop computer with a custom Lab- View (National Instruments, Austin, TX) user interface (Figure 1C), as well as to an ECG Trigger Monitor (Model 7800, Ivy Biomedical Systems, Branford, CT), which was connected to patient ECG leads. Ultrashort, 200 lsec pulsed square-waves are delivered to the wire tips at an operating frequency of 250 khz only when initiated by the RFG and when the Trigger Monitor detects the patient s R-wave. Delivery of RF energy continues for up to 5 sec (maximum cycle time), or until the creation of a channel is detected by the RFG algorithm. The Connector Cable allows for coupling of the wires in the sterile field to the RFG outside the sterile field. By energizing between the wire tips, channel creation is achieved between the two tips with minimal thermal injury. The PlasmaWire TM System was thoroughly tested on the bench and in several preclinical animal studies using patent and occluded arteries in ovine and porcine models, including detailed histopathology of arteries 24-hr post treatment, to ensure efficacy and safety. The preclinical tests and studies confirmed that effects of RF energy are localized to the treatment site between the coupled RF wire tips, with minimal collateral thermal effects and no perforations or myocardial injury attributed to RF energy delivery (Figure 2). There are two applications of the PlasmaWire TM System for channel creation. First, similar to the retrograde technique for recanalizing a CTO, one wire is delivered antegradely and another retrogradely. Then, RF energy is delivered between the two wire tips to create a channel between the antegrade lumen and the retrograde lumen (retrograde re-entry). The second application is to create an antegrade re-entry channel, in which both wires are antegradely delivered into a false lumen adjacent to the proximal end of the distal true lumen so that the tips of the two wires contact the distal fibrous cap. Then, RF energy is delivered to ablate the distal cap between the wire tips (antegrade reentry). Consequently, clear visualization of the CTO exit on angiogram is indispensable for successful antegrade re-entry with this system. The application of PlasmaWire TM is primarily dependent on the wire crossing strategy which is antegrade approach or retrograde approach. In this study, the CTO crossing strategy was left to each operator s judgement based on: (1) applicability of the collateral channel as a retrograde access route, (2) difficulty of antegrade wire crossing, which is affected by factors such as lesion morphology (CTO length, bend, abrupt occlusion, and calcification) and failed previous attempts. In both strategies, the PlasmaWire TM wires are delivered through microcatheters to the precise site for the ablation. The wires are manipulated under fluoroscopic guidance until the distal tips are at a predetermined distance from each other. For this study, an impedance measurement between the two distal tips was taken with an LCR meter (Model U1733C, Agilent, Santa Clara, CA) and one of five RFG output settings was selected according to the measured impedance and onsite assessment by the operators. Next, the proximal end of each wire was inserted into the two connectors of the Connector Cable, with the other end of the Connector Cable coupled to the RFG in the non-sterile field. RF activation was then initiated upon detection of the patient s R-wave. To maintain the position of the wire tips at the target during RF activation,

3 KANNO ET AL FIGURE 1 PlasmaWire TM System (RetroVascular, Inc.,). (A) Distal Tip of PlasmaWire TM, (B) Radiofrequency generator (RFG) with Connector Cable attached, (C) Laptop/user interface [Color figure can be viewed at wileyonlinelibrary.com] the rotating hemostasis valves on the microcatheters were tightened onto the wires. In this study, after proper positioning of the distal tips of the coupled wires was verified fluoroscopically (the gap being -typically <2 mm), RF energy was delivered until an electrical channel was created as determined by the RFG algorithm which continuously monitors signals during RF activation and detects a reduction in impedance between the two electrodes. Mechanical channel creation was then verified on angiography by tip injections through either microcatheter and simultaneous aspiration through either catheter in combination with contralateral injection, or by direct channel crossing using either of the PlasmaWire TM wires or a swapped extra-floppy guidewire. After wire crossing, the ablated channel was observed by IVUS. Balloon dilatation and stenting of the lesion was then carried out as per standard practice. 2.3 Study endpoints and definitions The primary endpoint of this FIH study was to demonstrate the effectiveness of this novel bi-polar RF wire system in making antegrade or retrograde re-entry for CTO recanalization as well as to report on the safety of this device. Antegrade or retrograde re-entry was achieved with mechanical channel creation. While electrical channel creation was detected by the RFG algorithm, mechanical channel creation was confirmed by IVUS, tip injection, and/or crossing of the re-entry channel with an extrafloppy wire as described above. Patient success was defined as successful recanalization (residual stenosis < 30%, TIMI flow 2) without MACCE. To examine the device safety, ECG was continuously recorded to detect arrhythmia induced by RF activation, and vessel injury at the ablation site such as vessel perforation and significant dissection with hematoma was checked by IVUS and angiography. Before stenting, distal embolism potentially induced by microbubble generation with RF activation was also checked by angiography. Other technical details such as delivered energy, elapsed RF activation time until channel creation, and procedure time from delivery of PlasmaWire TM to wire crossing were examined. The patients were clinically followed for 1 month to check MACCE. 2.4 Quantitative coronary angiography Coronary angiograms were analyzed using a validated edge detection system (QAngioXA Ver , Medis medical imaging systems, Leiden, Netherlands). FIGURE 2 Created channel by plasma-mediated ablation:(a) Clear channel created without charring in hotdog. (B) Channels created with minimal charring in bone. (C) Pathology findings in animal study (CTO in sheep superficial femoral artery): the red arrow indicates a created channel. The blue box indicates the magnified surface in the created channel. The yellowish green arrow indicates the very thin layer of tissue coagulation which suggests RF thermal injury [Color figure can be viewed at wileyonlinelibrary.com]

4 1048 KANNO ET AL. TABLE 1 3 RESULTS Clinical baseline and lesion characteristics Patient baseline Number of patients 7 Mean age 67 (1/211) Male gender, n(%) 7 (100%) OMI 5 (71.4%) CABG 0 Hypertension, n(%) 5 (71.4%) Dyslipidemia, n(%) 4 (57.1%) Diabetes, 4 (57.1%) ASO 1 (14.3%) Renal dysfunction 0 Number of diseased vessels MVD:3 (42.8%) EF 50 (1/215)% Lesion characteristics Number of target CTOs 7 Previously failed attempt 2 (28.6%) Blunt stump at CTO entry 2 (28.6%) Heavy calcification 4 (57.1%) Bifurcation at CTO entry 4 Bifurcation at CTO exit 4 Lesion length >20 mm 5 (71.4%) In-stent occlusion 2 (28.6%) OMI: old myocardial infarction, CABG: coronary artery bypass grafting, ASO: arteriosclerosis obliterans, MVD: multiple vessel disease, EF: ejection fraction, CTO: chronic total occlusion. Eligible patients were screened from October to December in 2015 and the FIH study was carried out in the same period. The patients were highly selected so that mechanical channel creation could be proven on angiography and/or IVUS. Consequently, seven patients (7 CTOs) were enrolled in this study. Clinical and target lesion characteristics are shown in Table 1, in which all patients were male and the frequent comorbidities were old myocardial infarction (71.4%), hypertension (71.4%), dyslipidemia (57.1%), and diabetes (57.1%) while post-bypass surgery and peripheral artery disease were rare (0%, 14.3%). Two of 7 targeted CTOs (28.6%) were previously attempted but failed. While blunt stump at CTO entry was 28.6%, heavy calcified CTO and long CTO (>20 mm) were frequent (57.1%, 71.4%). Two of 7 CTOs were old in-stent proliferative occlusion. Bifurcation at CTO exit was found in 4 of 7 CTOs (57.1%). In Table 2, the data of targeted CTO and RF activation in each patient are shown. Most of the targeted CTO were RCA-CTO (85.7%) and heavy calcium was seen at the ablation site in two cases. In one of them, blockage by heavy calcium to wire advancement was the reason of failure at the previous attempt (case TH). The PlasmaWire TM was used for retrograde re-entry in 5 cases and antegrade re-entry in two cases. In five cases, only a single activation of RF was required for electrical channel creation with short duration (<1.80 sec) and low energy (<1.99 joules). Multiple RF activation was required in two cases in which two activations failed to create an electrical channel in both cases. The reasons for needing multiple RF activations were difficulty in wire crossing through the created channels which had a zigzag course in one case (case KY) and the need for step-by-step advancement of the PlasmaWire TM wires after each ablation because of heavy calcium in the other (case TH). In Table 3, the results of plasma-mediated ablation are shown in each case. Electrical channel creation was detected by RFG algorithm in all cases. Mechanical channel creation was checked by wire crossing in all cases, IVUS in six cases and tip injection in three cases although the created channel was checked with IVUS after use of Rotablator due to extremely heavy calcium in case TH. The typical IVUS findings of created channel in case KY are shown in Figure 3. All cases were successfully recanalized through the created channel and stented except case KN in which the extra-floppy wire which initially crossed the channel was accidentally withdrawn and recrossing through the channel failed. Case FK is shown as a typical antegrade re-entry case in Figure 4. In this case, a recanalization channel with smooth contour was created with a very short single RF activation (0.4 sec) using very low energy (0.42 joules) as shown in Figure 4D. TABLE 2 Targeted CTO and RF activation data in each patient Patient initials Targeted CTO Heavy calcium at Number of ablation site Application of PW * activations Gap between wire tips (max) measured by QCA Elapsed RF activation time (max) Energy delivered at channel creation (max) KN Distal-RCA Present Retrograde re-entry mm 0.51 sec 0.79 joules FK Distal-RCA (bifurcation) Absent Antegrade re-entry mm 0.40 sec 0.42 joules YS Middle-LAD Absent Antegrade re-entry mm 1.80 sec 1.06 joules KB Proximal-RCA Absent Retrograde re-entry mm 0.67 sec 0.46 joules HS Middle-RCA Absent Retrograde re-entry mm 1.70 sec 1.99 joules KY Distal-RCA Absent Retrograde re-entry 5 (2) a 3.80mm (4.78 mm) b 2.40 sec (5.00 sec) c 2.30 joules (4.78 joules) d TH Middle-RCA Present Retrograde re-entry 5 (2) a 1.75 mm (3.24 mm) b 1.20 sec (5.00 sec) c 1.57 joules (4.25 joules) d a Number of failed activations are indicated in (). b Maximum gap at failed activation is indicated in (). c Elapsed RF time at failed activation is indicated in (). d Maximum energy delivered at failed activation is indicated in (). CTO: chronic total occlusion, RF: radiofrequency, PW*: PlasmaWire TM, QCA: quantitative coronary angiography.

5 KANNO ET AL TABLE 3 Results of plasma-mediated ablation in each patient Patient initials Electrical channel creation Mechanical channel creation Elapsed time from PW* delivery to CTO crossing Patient success Any complication a (in-hospital to 30 days) KN Success Success 13 min Success b None FK Success Success 18 min Success None YS Success Success 10 min Success None KB Success Success 14 min Success None HS Success Success 16 min Success None KY Success c Success 72 min Success None TH Success c Success 54 min Success None a MACCE, coronary rupture, extravasation, thrombosis, distal embolism and arrhythmia. b After the extra-floppy wire crossed the CTO through the created channel, the wire was accidentally withdrawn and re-crossing was failed. Therefore, the CTO was recanalized with reverse CART technique [4]. c Success was obtained by additional activations after failed activations (two times). CTO: chronic total occlusion, PW*: PlasmaWire TM. In single RF activation cases, wire crossing was quickly achieved with a mean elapsed time from PlasmaWire TM delivery to wire crossing of min (range min). However, wire crossing was difficult in case KY which required repeated channel creation (three times) in order to achieve retrograde re-entry because the course of these three channels was zigzag in nature. Also in case of TH, repeated channel creation (three times) was needed for penetrating heavy calcium. Positioning the tip of the PlasmaWire TM for ablation was difficult in this case and consequently wire crossing took 54 min. Patient success was achieved in all cases without MACCE at 1 month or any minor complications related to RF activation such as vessel perforation, thrombosis, distal embolism and arrhythmia. 4 DISCUSSION The present study illustrated the feasibility and safety of the Plasma- Wire TM System for channel creation in CTOs. The benefit of this device over conventional mechanical wires is considered to be its ability to efficiently create a channel without utilizing mechanical force which may minimize the chance of creating false channels. Therefore, it is anticipated that even in situations in which tissue penetration for re-entry is difficult with a mechanical wire due to subintimal dissections created around the distal true lumen, this novel RF wire system may reliably allow re-entry through channel creation. This is supported by the fact that both antegrade and retrograde re-entry was successfully achieved in all cases. Additionally, when utilizing this device, further expansion of the dissection is unnecessary for making re-entry unlike the Stingray TM System [11] (Boston Scientific, Marlborough, MA). Compared to previous RF wires, the PlasmaWire TM possesses properties very similar to mechanical CTO wires by incorporating the latest CTO wire technology. Unlike RF monopolar systems, the direction and ablation area can be more precisely controlled. So even if both wires are subintimal there is little risk of vessel perforation. In the bipolar system, wire advancement during RF activation is unnecessary for creating a channel within a predetermined length (<2.0 mm) because the channel is always created in the tissue between both wire tips. Obviously wire advancement during ablation may increase the risk of vessel perforation. In the present study, the tip of this wire was well controlled and vessel perforation was not observed as a result of plasma-mediated ablation in all cases. Additionally, the bipolar FIGURE 3 IVUS findings of the created channel in case KY. (A) IVUS findings at the 2nd ablation site after recanalization. The white arrow shows the created channel with smooth contour; however the floppy guide wire did not get through this channel due to the zigzag course of the channel. (B) PlasmaWire TM position at the 2nd ablation site (the gap was 3.80 mm by QCA): The white arrows show the tip of each PlasmaWires TM. IVUS: intravascular ultrasound

6 1050 KANNO ET AL. FIGURE 4 A typical antegrade re-entry case (case FK). (A) At preintervention, a CTO is seen in the middle of the right coronary artery (RCA) in simultaneous bilateral angiogram at LAO view. (B) Simultaneous bilateral angiogram at straight cranial view showed the CTO exit just at the bifurcation. (C) At plasma-mediated ablation, the gap between each PlasmaWire TM tip positioned as sandwiching the CTO exit (bifurcation) was 1.22 mm by QCA. (D) After the ablation, the created recanalization channel (indicated by a white arrow) was revealed using suction through the microcatheter and simultaneous contralateral injection. (E) IVUS showed antegrade re-entry created with ablation by PlasmaWire TM System just at the bifurcation. The single arrow indicates the true lumen of PL branch and the double arrow indicates the false lumen where each PlasmaWire TM wire was positioned. The triple arrow shows the re-entry channel connecting to the distal true lumen. (F) Final angiogram after stenting arrangement allows use of higher energy between both wire tips as compared to monopolar arrangement and can more efficiently create channels [12]. In most of the FIH cases, the energy delivered to create a channel was <2.0 J (range J) and the channels were created within 2 sec with single RF activation in all but two cases. For safety and more efficient channel creation, the gap between both wire tips was targeted to be within 2.0 mm in the present study based on the results of bench tests and animal studies. However, this seems to depend on the characteristics ofthetissuebetweenthewiretips.infact,achannelwassafelycreated with a gap >3.0 mm in two cases, while a shorter gap might be required forsuccessfulchannelcreationinheavilycalcifiedtissue. Although the mechanism of ablation using conventional RF wires is considered to be Joule heating, cellular vaporization and cavitation [7,13], as well as other mechanisms such as shock wave by plasma discharge (pulsed spark) [14] is suggested in the PlasmaWire TM System based on confirmation of shock wave generation in bench tests, minimum to no thermal injury in bench tests and animal studies, and channel creation in bone (Figure 2) and in heavy calcium as shown in this study. However, based on the present study, it appears that certain conditions, such as electrical characteristics of tissue to be ablated (e.g., impedance, phase angle) and extent of contact between the wire tip and the tissue, likely play a role in successfully creating a channel and still need to be better defined. Further clinical studies are necessary to clarify the clinical effectiveness and limitations of the PlasmaWire TM System. For example, the mean elapsed time from PlasmaWire TM delivery to wire crossing after ablation in this study was short in cases with single RF activation because the utilization of this device in those cases involved simply making a re-entry at the proximal or distal end of CTO. However, when this device is used for channel creation within the CTO body, multiple RF activations might be required for making a recanalization channel and it might take time for wire crossing. Therefore, how to efficiently apply this device for CTO crossing should be studied. 5 CONCLUSIONS In the present study, the PlasmaWire TM System was shown to facilitate CTO crossing with channel creation safely and effectively with low

7 KANNO ET AL total RF energy delivered even in dense calcified tissue. This device was useful to safely create not only retrograde re-entry but also antegrade re-entry by controlled tissue ablation and the potential of the PlasmaWire TM System to reduce procedure time by reliably ablating tissue in a few seconds was indicated. Larger, prospective clinical studies should be carried out to confirm these promising preliminary results. CONFLICT OF INTEREST O Katoh is a co-founder of RetroVascular Inc. The other authors have no conflicts of interest to declare. ORCID Daitaro Kanno MD REFERENCES [1] Suero JA, Marso SP, Jones PG, et al. Procedural outcomes and long-term survival among patients undergoing percutaneous coronary intervention of a chronic total occlusion in native coronary arteries: A 20-year experience. J Am Coll Cardiol 2001;38:409. [2] Stone GW, Reifart NJ, Moussa I, et al. Percutaneous recanalization of chronically occluded coronary arteries: A consensus document: part II. Circulation 2005;112:2530. [3] Saito S, Tanaka S, Hiroe Y, et al. Angioplasty for chronic total occlusion by using tapered-tip guidewires. Catheter Cardiovasc Interv 2003;59:305. [4] Surmely JF, Tsuchikane E, Katoh O, et al. New concept for CTO recanalization using controlled antegrade and retrograde subintimal tracking: The CART technique. J Invasive Cardiol 2006;18:334. [5] Kimura M, Katoh O, Tsuchikane E, et al. The efficacy of a bilateral approach for treating lesions with chronic total occlusions the CART (controlled antegrade and retrograde subintimal tracking) registry. JACC Cardiovasc Interv 2009;2:1135. [6] Tsuchikane E, Katoh O, Kimura M, et al. The first clinical experience with a novel catheter for collateral channel tracking in retrograde approach for chronic coronary total occlusions. JACC Cardiovasc Interv 2010;3:165. [7] Slager CJ, Essed CE, Schuurbiers JH, et al. Vaporization of atherosclerotic plaques by spark erosion. J Am Coll CardioI 1985;5:1382. [8] Morales PA, Heuser RR. Chronic total occlusions: Experience with fiber-optic guidance technology optical coherence reflectometry. J Interv Cardiol 2001;14:611. [9] Baim DS, Braden G, Heuser R, et al. Utility of the safe-cross-guided radiofrequency total occlusion crossing system in chronic coronary total occlusions (results from the guided radio frequency energy ablation of total occlusions registry study). Am J Cardiol 2004;94: 853. [10] Baerlocher MO, Asch MR, Myers A. Successful recanalization of a longstanding complete left subclavian vein occlusion by radiofrequency perforation with use of a radiofrequency guide wire. J Vasc Interv Radiol 2006;17:1703. [11] Werner GS, Schofer J, Sievert H, et al. Multicentre experience with the BridgePoint devices to facilitate recanalisation of chronic total coronary occlusions through controlled subintimal re-entry.. EuroIntervention 2011;7:192. [12] Cosman ER Jr, Gonzalez CD. Bipolar radiofrequency lesion geometry: Implications for palisade treatment of sacroiliac joint pain. Pain Practice 2011;11:3. [13] Shimko N, Savard P, Shah K. Radio frequency perforation of cardiac tissue: Modelling and experimental results. Med Giol Eng Comput 2000;38:575. [14] Fridman A, Friedman G. Mechanisms and characteristics of plasma discharges in water. In: Fridman A, Friedman G, editors. Plasma Medicine. Chichester, WS, UK: Wiley-Sons; pp 25. How to cite this article: Kanno D, Tsuchikane E, Nasu K, et al. Initial results of a first-in-human study on the PlasmaWire TM System, a new radiofrequency wire for recanalization of chronic total occlusions. Catheter Cardiovasc Interv. 2018;91: