Conventional Guidewire Research Articles

Evaluation of novel balloon pulmonary angioplasty using intravascular ultrasound for total occlusion lesions and blood flow in the postprocedural phase after initially unsuccessful procedures.

Outcomes of balloon pulmonary angioplasty (BPA) using intravascular ultrasound (IVUS) with a rounded tip to cross a total occlusion lesion in chronic thromboembolic pulmonary hypertension without passing a conventional guidewire remain unclear. Even in initially unsuccessful cases of total occlusion lesions, improved blood flow may be observed in the postprocedural phase as a result of breaking the thrombosis cap surface. The aim of the study was to verify the initial success of BPA with a new technique using IVUS for total occlusion lesions and to evaluate peripheral blood flow in the postprocedural phase in initially unsuccessful cases. Initial success rate and associated factors were evaluated in 50 total occlusion lesions by attempted IVUS passage using a new technique without a preceding guidewire from August 2016 to February 2024. Peripheral blood flow improvement in the postprocedural phase among initially unsuccessful cases was investigated via subsequent angiographic examination or during follow-up. The success rate was 54%, and the sole determinant of success was the angle of the lesion. Peripheral perfusion improved in 15 of 23 initially unsuccessful cases in the postprocedural phase. Even in the unsuccessful cases, significant improvement in peripheral perfusion occurred in the postprocedural phase in the patients undergoing dilatation with the balloon advanced partway into the total occlusion lesion to confirm intravascular location of the balloon (P = .0257). BPA treatment of total occlusion lesions may improve perfusion in the postprocedural phase even following an initially unsuccessful treatment. Maximizing use of IVUS may provide an adjunctive role in BPA of total occlusion lesions.

Pharmacological Modulation of Intrarenal Pressure in a Porcine Model Using a Novel Isoprenaline-Eluting Guidewire.

Introduction: Several complications of retrograde intrarenal surgery have been attributed to inadvertent increases in intrarenal pressure. We recently described the development of an innovative isoprenaline-eluting guidewire (IsoWire). The objective of this study was to investigate the impact of this IsoWire on the intrarenal pressure and evaluate its safety. Materials and Methods: This study was performed in 17 renal units using a porcine model. As controls, the intrarenal pressure, heart rate, and mean arterial pressure were measured for a duration of six minutes with a standard guidewire placed in the renal pelvis. For the experiment, the conventional guidewire was substituted with the IsoWire and the same parameters were measured. Blood samples were taken at one-minute intervals to measure plasma isoprenaline levels. This procedure was repeated on the opposite side. Results: The mean intrarenal pressure reduction was 29% (95% CI: 13%-53%). The mean isoprenaline effect time was 174 seconds. No changes in heart rate (p = .908) or mean arterial pressure (p = .749) were recorded after IsoWire insertion. Plasma isoprenaline levels were below the quantitation threshold. Isoprenaline concentrations in the plasma were below the quantification threshold. Ureteroscopy revealed no ureteral lesions. Conclusions: The IsoWire demonstrated a safe and effective reduction of intrarenal pressure. Additional research is necessary to determine whether ureteral smooth muscle relaxation generated by isoprenaline facilitates easier insertion of a ureteral access sheath, decreases the incidence of ureteral access sheath related ureteral lesions, or even encourage the practice of sheathless retrograde intrarenal surgery.

Design and hierarchical analysis of magnetic actuated robot: A governing equation based approach

As the alternative solution to the conventional guidewire, the magnetic robot can help interventionists perform percutaneous coronary intervention (PCI) because magnetic fields are transparent and safe for biological tissues. Despite extensive research on magnetic robots, the exploration of their deflection control for practical applications still requires further research. In this paper, a hierarchical analysis framework (HAF) is proposed to control the magnetic robot’s deflection. Six deflection subpatterns are analyzed through HAF, incorporating statistical and regression analyses to establish governing equations of magnetic robots. The performance of the control equations is validated through precise control of the magnetic continuum robot (MCR) and magnet-tipped robot (MTR) in both uniform and gradient magnetic fields. Experimental results show that under the uniform magnetic field, the average root mean square error (RMSE) of governing equation of MCR is 0.08±0.05°, 0.41±0.34°, 1.47±0.49° and 1.07±0.66° for four-types horizontal deflection, 0.19±0.07mm and 0.16±0.10mm for two-types vertical deflection, respectively. Based on the governing equations, the MTR is able to precisely navigate to coronary arteries with various degrees of stenosis (30%, 52%, and 60%), and successfully pass through a series of rings, with an average error of 1.05 mm. The research successfully demonstrates the potential of HAF in creating robust and reliable governing equations for magnetic actuation in medical robotics, with significant implications for enhancing the precision and safety of PCI procedures.

Efficacy of a Newly Developed Guidewire for Selective Biliary Cannulation: A Multicenter Randomized Controlled Trial.

Various guidewires are used for biliary cannulation, and each one has its own characteristics affecting its effectiveness. This study aimed to measure the basic properties and evaluate the effectiveness of a newly developed 0.025-inch guidewire for selective biliary cannulation. A total of 190 patients at five referral hospitals were randomly allocated to undergo selective biliary cannulation using the newly developed guidewire (NGW group, n = 95) or a conventional guidewire (CGW group, n = 95). The primary outcome was the selective biliary cannulation rate in naïve papillae. The secondary outcome was to measure the NGW basic properties, compare them with those of the CGW, and analyze the importance of basic property differences. There were no significant differences between the groups in the baseline characteristics. The primary outcome (75.8% vs. 84.2%, p = 0.102) and adverse event rate (6.3% vs. 4.2%, p = 0.374) were similar in both groups. However, compared with the CGW group, the NGW group showed a higher number of ampulla contacts (2.58 vs. 2.02, p = 0.011) and longer cannulation time (216.5 vs. 135.1 s, p = 0.016). Furthermore, the NGW group had higher maximum friction (34.6 ± 1.34 vs. 30.2 ± 4.09), lower stiffness, and better elastic resiliency. In the multivariate analysis, a curved-tip GW (OR = 0.26, 95% CI 0.11-0.62, p = 0.002) and normal papillary shape (OR = 0.39, 95% CI 0.17-0.86, p = 0.021) were contributing factors for successful selective biliary cannulation. The NGW group had high friction and low stiffness, characteristics affecting biliary cannulation. Clinically, the NGW group had similar success and adverse event rates as the CGW, but they showed a higher number of ampulla contacts and longer cannulation time.

Practical use of dual-lumen catheter-facilitated reverse wire technique for nonhighly angulated side branch

Dual-lumen catheter (DLC)-facilitated reverse wire technique is considered a method of last resort for inserting a guidewire into a markedly angulated side branch. Moreover, this technique can be practically applied to other types of anatomical variations around the bifurcation. Case 1 was that of a 53-year-old man with a tight stenosis of the proximal left anterior descending artery at the diagonal bifurcation with angiographically apparent coronary dissection. We successfully achieved guidewire insertion into the targeted branch using the DLC-facilitated reverse wire technique. Case 2 involved a 78-year-old man with total occlusion of the mid-portion of the right coronary artery. The guidewire reentry point in the atrioventricular branch was slightly distant from the true distal end of the occlusion. We successfully used the DLC-facilitated reverse wire technique to pass a second guidewire to the posterodescending artery. Case 3 was that of an 80-year-old man whose coronary artery had an aneurysm with severe stenoses at both entry and exit of the aneurysm. We adopted the DLC-facilitated reverse wire technique and easily advanced the guidewire by matching the guidewire advancing path with the direction of the sequential conduit constituted by the coronary aneurysm and stenosis. The timing of decision-making to try the DLC-facilitated reverse wire technique is important. The lesion for which reverse wiring is suitable is usually difficult to be treated with conventional guidewire crossing. We have to promptly judge the validity of applying this technique based on the angiographic findings of targeted lesions and take immediate action to implement this procedure to reduce the procedural time and irradiation dose.

Novel J-tip guidewire for reintervention after stent-by-stent placement in patients with malignant hilar biliary obstruction

Reintervention (RI) after bilateral metal stent placement for malignant hilar biliary obstruction is a highly technically challenging procedure. This study aimed to examine the use of a novel J-tip guidewire (GW) for RI after stent-by-stent (SBS) placement. The study outcomes included technical success, procedure time, and procedure-related adverse events associated with RI after SBS placement. These parameters were compared between 20 patients who underwent RI using the J-tip GW (J-GW group) and a control cohort of 20 patients who underwent RI using a conventional GW (C-GW group). The technical success rate of GW placement without any advanced technique was significantly higher in the J-GW group than that in the C-GW group. The median procedure time was significantly shorter in the J-GW group. No significant differences on the procedure-related adverse event rate were observed between the groups. The novel J-tip GW yielded higher technical success rates with appropriate GW placement and shorter procedure time for RI after SBS placement, simplifying and streamlining the RI procedure.

Telerobotic neurovascular interventions with magnetic manipulation.

Advances in robotic technology have been adopted in various subspecialties of both open and minimally invasive surgery, offering benefits such as enhanced surgical precision and accuracy with reduced fatigue of the surgeon. Despite the advantages, robotic applications to endovascular neurosurgery have remained largely unexplored because of technical challenges such as the miniaturization of robotic devices that can reach the complex and tortuous vasculature of the brain. Although some commercial systems enable robotic manipulation of conventional guidewires for coronary and peripheral vascular interventions, they remain unsuited for neurovascular applications because of the considerably smaller and more tortuous anatomy of cerebral arteries. Here, we present a teleoperated robotic neurointerventional platform based on magnetic manipulation. Our system consists of a magnetically controlled guidewire, a robot arm with an actuating magnet to steer the guidewire, a set of motorized linear drives to advance or retract the guidewire and a microcatheter, and a remote-control console to operate the system under real-time fluoroscopy. We demonstrate our system's capability to navigate narrow and winding pathways both in vitro with realistic neurovascular phantoms representing the human anatomy and in vivo in the porcine brachial artery with accentuated tortuosity for preclinical evaluation. We further demonstrate telerobotically assisted therapeutic procedures including coil embolization and clot retrieval thrombectomy for treating cerebral aneurysms and ischemic stroke, respectively. Our system could enable safer and quicker access to hard-to-reach lesions while minimizing the radiation exposure to physicians and open the possibility of remote procedural services to address challenges in current stroke systems of care.

Reducing the Guidewire Friction for Endovascular Interventional Surgery by Radial Micro-Vibration

Guidewires for endovascular interventional surgery are inevitably affected by high frictional resistance because of direct contact with the vascular wall, which greatly reduces the operation efficiency and safety. This article presents a method of applying radial ultrasonic microvibration at the proximal end of a conventional passive guidewire to reduce the frictional resistance. The proposed method theoretically reduced the frictional resistance by reducing the friction coefficient, actual contact area, and the net friction time between the guidewire and vascular wall. The effectiveness of the proposed method was experimentally demonstrated in designed simulations of the blood vessel environment, where the influences of the vibration amplitude on the drag reduction effect were considered. The results indicated that vibrating the guidewire at the resonant frequency with the designed device clearly reduced the drag with a maximum frictional reduction rate of 85.19%. At the resonant frequency, the change in frictional resistance showed a linear negative correlation with the applied vibration amplitude. The proposed method offers a new approach to improving the efficiency and safety of vascular interventional surgery.

Abstract TMP61: Telerobotic Neurovascular Interventions With Magnetic Manipulation

Background: Advances in robotic technology have been adopted in various subspecialties of both open and minimally invasive surgery, offering benefits such as enhanced surgical precision and accuracy with reduced efforts and fatigue. Despite the advantages, robotic applications to endovascular neurosurgery have remained largely unexplored due to technical challenges such as the miniaturization of robotic devices that can navigate the complex and tortuous cerebral vasculature. Although some commercial robotic systems enable precise manipulation of conventional guidewires for coronary and peripheral vascular interventions, they remain unsuited for neurovascular applications due to the considerably smaller and more tortuous anatomy of cerebral arteries. Methods: We present a teleoperated robotic system designed for neurovascular interventions based on magnetic steering and navigation. Our system consists of a magnetically controlled guidewire, a robot arm with a permanent magnet attached to its end-effector for steering control of the guidewire, a set of motorized linear drives to advance or retract the guidewire and a microcatheter, and a remote-control console to operate the system under feedback from real-time fluoroscopic imaging and visualization. Results: With a life-sized neurovascular phantom, we demonstrate the navigational capability to reach several branches of circle of Willis and distal cerebral vasculature with the magnetic guidewire under teleoperation of the system. We further demonstrate telerobotically-assisted therapeutic procedures including coil embolization and clot retrieval thrombectomy for intracranial aneurysms and ischemic stroke, respectively. Conclusion: Our telerobotic neurointerventional platform could enable safer and quicker access to hard-to-reach lesions, significantly reduce operative time and perioperative risk by reducing intravascular manipulation, minimize the radiation exposure to interventionalists, and open the possibility of remote procedural services to address challenges in current stroke systems of care. Note: Animal testing will be performed in Q3 2021 and the results will be presented at ISC.

A novel intracranial exchange guidewire improves the navigation of various endovascular devices: An in vitro study of challenging situations.

Neuroendovascular procedures rely on successful navigation and stable access to the target vessel. The Stabilizer is a 300 cm long exchange wire with a 0.014 diameter and a soft, flexible stent at the distal end designed to assist with navigation and device delivery. This study aims to assess the efficacy of the Stabilizer for navigation in a variety of challenging environments. The efficacy of the Stabilizer was evaluated using three challenging vascular models: a giant aneurysm model, a severe tortuosity model, and an M1 stenosis model. The Stabilizer was compared with a conventional wire during navigation in each model. In the giant aneurysm model, there was no significant difference of success during straightening of a looped wire and significantly higher success rates when advancing an intermediate catheter with the Stabilizer beyond the aneurysm neck compared to a conventional guidewire. The Stabilizer also significantly increased success rates when advancing an intermediate catheter through a model with severe tortuosity compared to a conventional guidewire, as well as exchange maneuver for intracranial stenting in a stenosis model compared to an exchange wire. In our experimental model, the Stabilizer significantly improved navigation and device delivery in a variety of challenging settings compared to conventional wires.

Magnetic Control of a Steerable Guidewire Under Ultrasound Guidance Using Mobile Electromagnets

Endovascular surgery has become a popular minimally invasive approach to diagnose and treat various vascular diseases. However, manipulating conventional passive guidewires and catheters still has technical challenges, such as long duration and undesired trauma. In addition, radiation exposure induced by commonly used fluoroscopic imaging has safety concerns. This letter presents a workflow that performs magnetic control of a steerable guidewire under ultrasound (US) guidance to address these issues. The designed magnetically steerable guidewire is fabricated by replica molding method, then a computational-efficient kinematic model is proposed to describe the relationship between the applied magnetic field and tip deformation. The constructed magnetic actuation system integrates three electromagnets and a US probe into a parallel mechanism, realizing large-workspace magnetic field generation and US feedback. Further, a motorized feeder is incorporated to provide the forward and backward motion of the guidewire. An autonomous control framework is proposed consisting of preoperative and intraoperative stages, through which the guidewire can be delivered to the targeted region automatically. Results show that the proposed kinematic model efficiently estimates the deformation of the guidewire. Furthermore, the overall procedure is experimentally validated on a phantom mimicking vascular structures. This letter provides a preliminary robotic solution to improve catheterization procedures by introducing magnetic actuation and US imaging.

Utility and safety of a new uneven double-lumen sphincterotome in cases of difficult biliary cannulation

BackgroundWe investigated the utility and safety of a new uneven double-lumen sphincterotome in biliary cannulation in comparison with the conventional pancreatic guidewire (PGW) method.MethodsWe retrospectively evaluated 119 patients who required PGW placement because of difficult biliary cannulation. Endoscopic retrograde cholangiopancreatography (ERCP) was performed using a conventional ERCP catheter or a new uneven double-lumen sphincterotome. The success rate of bile duct cannulation, the operation time of bile duct cannulation, and the incidence of post-ERCP pancreatitis (PEP) were evaluated.ResultsForty-four patients were treated with a new double-lumen sphincterotome (the new sphincterotome group) and 75 patients underwent conventional PGW placement (the conventional group). The success rate of bile duct cannulation was 39/44 (88.6%) in the new sphincterotome group and 63/75 (84.0%) in the conventional group (not significant). The total biliary cannulation time (from the reach to the papilla to the finish of biliary cannulation) was 16.0 (6.5–78) min in the new sphincterotome group and 26.0 (5–80) min in the conventional group (P < 0.01). The time from PGW placement to bile duct cannulation was 3.5 (0.3–57) min in the magictome group and 12.0 (1–65) min in the conventional group (P < 0.01). Hyperamylasemia was observed in 13/44 (29.5%) and 17/75 (22.7%), respectively (not significant). Five of 44 (11.3%) of the new sphincterotome group and 14/75 (18.7%) of the conventional group were diagnosed with PEP (not significant).ConclusionA new double-lumen sphincterotome allows selective bile duct cannulation to be performed in a shorter time than the conventional PGW method.

S2379 A Unique Approach in Selective Guidewire Cannulation of a Complex Malignant Biliary Stricture

INTRODUCTION: Digital single-operator cholangioscopy (D-SOC), such as Spyglass DS, represents newer technology that can improve the diagnostic and therapeutic capabilities of ERCP. In the case below, we present how the use of Spyglass aided in the decompression of a complex malignant biliary stricture. CASE DESCRIPTION/METHODS: 52 year old male presented with epigastric pain, and obstructive jaundice. Patient has known portal vein thrombosis, and metastatic adenocarcinoma to the liver and lungs. The primary is suspected to be of upper GI or pancreatobiliary origin.CBC, PT INR, and BMP were within normal limits. T Bili is 17 mg/dL, D Bili 12.5 mg/dL, Alk Phos 1441 units/L, AST 300 units/L, ALT 251 units/L, AFP 11.5 ng/mL, CEA 249.8 ng/mL, and CA 19–9 113,888 units/mL. MRCP: Abrupt cut off of the distal common hepatic duct with intrahepatic bile duct dilatation.ERCP found 2 high grade biliary strictures. Conventional guidewire cannulation of the strictures were unsuccessful.A second ERCP was performed with the aid of Spyglass DS. Under direct visualization from Spyglass and fluoroscopy, guidewire cannulation of the high-grade common bile duct and hepatic duct strictures were achieved. A fully covered 10 Fr x 80mm metal stent was advanced over the guidewire and deployed across both strictures. Then, the waist of the stent was balloon dilated to 6 mm. Biliary drainage was confirmed upon scope retraction. Patients bilirubin downtrended and he was discharged with oncology follow up. DISCUSSION: The incidence of malignancy related biliary obstruction is increasing. The majority of these patients will benefit from biliary decompression in order to improve quality of life. Given the complications associated with percutaneous transhepatic biliary drains and stenting of biliary strictures, therapeutic ERCP is the favored approach. However, even the most experienced endoscopists fail to cannulate malignant strictures 5-10% of the time with conventional ERCP. Based on our experience, the utility of Spyglass DS might be of benefit when managing difficult malignant biliary strictures. Upon our literature review, the use of D-SOC guided cannulation of these strictures were found in only 11 patients, with 64% having cholangiocarcinoma. With the aid of D-SOC, the success rate of cannulation was 46%. Given limited literature, more research for this procedural indication should be considered as D-SOC could be a viable approach in improving the effectiveness of endoscopic management of these complex malignant strictures.

Novel Panna Guide Wire Facilitates Percutaneous and Nonfluoroscopic Procedure for Atrial Septal Defect Closure: A Randomized Controlled Trial.

Echo-guided percutaneous procedures have been reported reliable and advantageous. However, the learning curve is difficult for junior doctors. We aimed to evaluate the safety and efficacy of a novel guidewire (Panna wire) in percutaneous atrial septal defect closure under transthoracic echocardiography guidance only. The Panna wire is designed for echo-guide procedure with a retractable spindle-shaped tip. A multicenter, randomized, controlled trial was conducted to evaluate the safety and efficacy of the Panna wire versus the conventional guidewire for junior doctors with <100 cases experience. The primary outcome was operative success rate. The secondary outcomes were incidence of major adverse events, operation time, time needed to enter the left atrium, number of arrhythmia episodes, number of misguidance to tricuspid valve, and incidence of peripheral vascular complications. Between July 2018 and September 2019, 100 patients with atrial septal defect were randomized to either the Panna wire group (n=52) or the conventional wire group (n=48) at 3 centers. The baseline clinical characteristics were similarly distributed. The operative success rate (primary outcome) was 100% in the Panna wire group versus 68.75% in the conventional wire group (P<0.001). No major adverse events occurred in either group. Significant differences in favor of the Panna wire group were found in operation time (P=0.004), time needed to enter the left atrium (P<0.001), number of arrhythmia episodes (P<0.001), and number of misguidance to tricuspid valve (P=0.005). The Panna wire is safe and effective and reduces the learning curve in percutaneous atrial septal defect closure under transthoracic echocardiography guidance only. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT04096924.

Sharp recanalization of peripheral arterial chronic total occlusions.

Peripheral arterial chronic total occlusions (CTOs) usually have calcified caps at either ends. When attempting endovascular recanalization, these calcified CTO caps may prevent the interventionist in crossing the lesion with conventional catheter and guidewire techniques. Using specialized CTO devices or re-entry devices can help crossing the CTO, but such devices are usually expensive, not always readily available and require specialist training prior to usage."Sharp recanalization" is an alternative method of crossing the CTOs. If it is not possible to cross the CTO with conventional catheter and guidewire technique, one can take out the floppy end of the guidewire and use the stiff or the "sharp" end of the guidewire to break the hard CTO cap. Once the CTO cap is broken, the stiff end is replaced by the floppy end of the guidewire again to proceed with balloon angioplasty and/or stenting.In order to safely use the sharp recanalization technique while minimizing the risk of perforation, sharp recanalization should only be attempted once conventional methods have failed. The interventionist should plan sharp recanalization with the vascular path in mind and decide in advance how far s/he will proceed. It can be helpful to set a time limit together with the intervention team, past which the sharp recanalization attempt will be abandoned. Using straight catheters can help directing the stiff guidewire tip to the center of the vascular lumen and reduce the risk of sub intimal dissection or arterial wall perforation.

IVUS Assessment of the Crossing Pathway of an Intraluminal Reentry Device Used in the Primary Treatment of Infrainguinal Chronic Total Occlusions

Purpose: To examine with intravascular ultrasound (IVUS) the crossing pathways of the TruePath reentry device during primary antegrade recanalization of infrainguinal chronic total occlusions (CTOs). Methods: Between July 2017 and September 2018, a prospective multicenter study enrolled 143 consecutive patients (mean age 75±9 years; 101 men) with 146 CTOs treated in an antegrade approach using the TruePath reentry device with IVUS assessment of the crossing pathway in successful cases. Outcome measures were complete success (reentry device reached the distal true lumen), assisted success (reentry device use followed by a conventional guidewire to reach the distal true lumen), reentry device crossing route by IVUS assessment, and procedure- and device-related complications. Regression analyses were employed to identify any relevant associations between baseline patient variables and the outcome measures; results are presented as the odds ratio (ORs) and 95% confidence interval (CI). Results: Complete success was achieved in 82 (56.2%) lesions; any success (complete plus assisted) was documented in 117 (80.1%) lesions. Four (3%) perioperative device-related complications were observed. The crossing route was intraplaque for most of the total crossing distance in both complete success cases (95.3%±13.2%) and any success cases (94.8%±14.4%), with relatively short subintimal (3.6%±10.2% and 4.2%±11.2%, respectively) or intramedial (1.2%±5.8% and 1.0%±5.4%, respectively) crossing. CTO length was a significant risk factor for not achieving complete success (OR 1.74, 95% CI 1.13 to 2.68, p=0.012), and a history of failed revascularization was associated with not achieving any success (OR 6.40, 95% CI 1.28 to 28.9, p=0.038). Conclusion: The intraplaque route was the primary pathway taken by the TruePath reentry device as it crossed infrainguinal CTOs. Crossing rates were acceptable, with few device-related complications. However, a longer CTO length and a failed revascularization history negatively affected the success rate.

Magnetic Particle Imaging–Guided Stenting

Purpose:To assess the feasibility of magnetic particle imaging (MPI) to guide stenting in a phantom model. Materials and Methods: MPI is a new tomographic imaging method based on the background-free magnetic field detection of a tracer agent composed of superparamagnetic iron oxide nanoparticles (SPIOs). All experiments were conducted on a custom-built MPI scanner (field of view: 29-mm diameter, 65-mm length; isotropic spatial resolution 1–1.5-mm). Stenosis phantoms (n=3) consisted of polyvinyl chloride (PVC) tubes (8-mm inner diameter) prepared with centrally aligned cable binders to form a ~50% stenosis. A dedicated image reconstruction algorithm allowed precise tracking of endovascular instruments at 8 frames/s with a latency time of ~115 ms. A custom-made MPI-visible lacquer was used to manually label conventional guidewires, balloon catheters, and stainless steel balloon-expandable stents. Vascular stenoses were visualized by injecting a diluted SPIO tracer (ferucarbotran, 10 mmol iron/L) into the vessel phantoms. Balloon angioplasty and stent placement were performed by inflating balloon catheters and stent delivery balloons with diluted ferucarbotran. Results: After deployment of the stent, the markers on its ends were clearly visible. The applied lacquer markers were thin enough to not relevantly alter gliding properties of the devices while withstanding friction during the experiments. Placing an optimized flexible lacquer formulation on the preexisting radiopaque stent markers provided enough stability to withstand stent expansion. Final MPA confirmed successful stenosis treatment, facilitated by the disappearance of the lacquer markers on the stent due to differences in SPIO concentration. Thus, the in-stent lumen could be visualized without interference by the signal from the markers. Conclusion: Near real-time visualization of MPI-guided stenting of stenoses in a phantom model is feasible. Optimized MPI-visible markers can withstand the expansion process of stents.

Integrated Stent Delivery System: A Next Generation of Stent Delivery and Drug-Eluting Stent.

The SLENDER Integrated Delivery System (IDS™) is an 'all-in-one' fixed-wire coronary stenting device designed for direct stenting, precluding the need for conventional guidewires and predilatation balloons. It achieves ultra-low profiles (crossing profiles as low as 0.029″/0.737 mm), enabling the downsizing of catheters to facilitate transradial intervention in a large subsets of patients. The IDS represents the first advance in coronary stent delivery since the introduction of rapid-exchange stent delivery systems >20 years ago. SLENDER IDS has demonstrated non-inferiority compared with commercial DES, excellent long-term safety and a potentially more efficient approach to PCI where patient comfort is enhanced, procedures are streamlined, and resource consumption is reduced. This paper will summarize the novel features of this new stent delivery system and the early clinical data demonstrating safety and efficacy.

Effectiveness of the PowerWire Radiofrequency Guidewire in Recanalizing Chronically Occluded Iliac Venous Stents

Iliac venous stenting is a commonly performed procedure in treating post-thrombotic and nonthrombotic iliac venous disease. Whereas overall stent patency rates are high, stent occlusion does occur. Recanalizing chronically occluded stents is technically challenging and often impossible with conventional guidewires and catheters. The PowerWire (Baylis Medical, Burlington, Mass) radiofrequency guidewire is a 0.035-inch guidewire that delivers radiofrequency energy at the end of the guidewire. A retrospective chart review was conducted of patients with chronically occluded iliac venous stents who underwent an iliac venous recanalization attempt using the PowerWire from March 2015 to June 2018. A total of 15 patients underwent a recanalization attempt with the PowerWire. All patients had initial unsuccessful attempts at recanalizing the occluded iliac vein stents with conventional guidewires. Successful recanalization was defined as restoration of antegrade iliac venous flow after angioplasty alone or angioplasty and placement of additional stents. Percutaneous recanalization of chronically occluded iliac venous stents using the PowerWire was successful in 10 patients. Cumulative 6-month patency rate was 62%. Cumulative 12-month patency rate was 43%. There were two complications that occurred with use of the PowerWire. One patient had transient footdrop of the ipsilateral limb that was successfully recanalized. One patient had self-limited perforation of the left common iliac artery during unsuccessful recanalization. The PowerWire is an effective and relatively safe device for recanalizing chronically occluded iliac venous stents.

A Magnetically Controlled Soft Microrobot Steering a Guidewire in a Three-Dimensional Phantom Vascular Network.

Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional in vitro tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.