Magnetic Guidewire Research Articles

Magnetic Field Control Using an Electromagnetic Actuation System with Combined Air‐Core and Metal‐Core Coils

Magnetic fields are widely utilized for remote control of magnetic objects, with various actuation systems developed for manipulating miniature robots in research and biomedical applications. When designing a manipulation system providing a uniform magnetic field, it is also important to consider both the accessibility of the workspace and the integration of imaging tools. This article presents an electromagnetic coil system that manipulates magnetic objects within a 3D space, enhancing the magnetic field in an upward orientation. The system includes eight metal‐core coils arranged hemispherically to ensure unimpeded access to the workspace and imaging tools, along with two air‐core coils. Easier control and repeatability of the magnetic field are achieved using two joysticks and sequential programming. The versatility of the system is demonstrated by using it to manipulate a magnetic guidewire and to guide micromagnets to various targets. Additionally, using this system, oscillating magnetic fields effectively control swarms of magnetic nanoparticles, enabling operations such as dispersion, assembly, and ribbon‐like shape formation. Furthermore, the manipulation of cell‐based microrobots (cell‐bots) showcases the system's capability to handle single and multiple cell‐bots, facilitating their collection while preserving cell viability. These experiments underscore the system's potential for fundamental biomedical research and various applications.

Shortwave Infrared Imaging of a Quantum Dot-Based Magnetic Guidewire Toward Non-Fluoroscopic Peripheral Vascular Interventions.

Peripheral vascular interventions (PVIs) offer several benefits to patients with lower extremity arterial diseases, including reduced pain, simpler anesthesia, and shorter recovery time, compared to open surgery. However, to monitor the endovascular tools inside the body, PVIs are conducted under X-ray fluoroscopy, which poses serious long-term health risks to physicians and patients. Shortwave infrared (SWIR) imaging of quantum dots (QDs) has shown great potential in bioimaging due to the non-ionizing penetration of SWIR light through tissues. In this paper, a QD-based magnetic guidewire and its system is introduced that allows X-ray-free detection under SWIR imaging and precise steering via magnetic manipulation. The QD magnetic guidewire contains a flexible silicone tube encapsulating a QD polydimethylsiloxane (PDMS) composite, where HgCdSe/HgS/CdS/CdZnS/ZnS/SiO2 core/multi-shell QDs are dispersed in the PDMS matrix for SWIR imaging upon near-infrared excitation, as well as a permanent magnet for magnetic steering. The SWIR penetration of the QD magnetic guidewire is investigated within an artificial tissue model (1% Intralipid) and explore the potential for non-fluoroscopic PVIs within a vascular phantom model. The QD magnetic guidewire is biocompatible in its entirety, with excellent resistance to photobleaching and chemical alteration, which is a promising sign for its future clinical implementation.

Kirchhoff rod-based three-dimensional dynamical model and real-time simulation for medical-magnetic guidewires

Background and Objective: Magnetic guidewire, fabricated from hard-magnetic soft composites, has recently emerged as an appropriate candidate for magnetic actuation systems to perform intravascular surgical navigation, owing to its elastic, magnetically steerable properties and good interphase with biological tissues. A suitable and efficient mathematical model for the magnetic guidewire is essential in the system to execute remote manipulation and active control. Methods: This paper presents a real-time Kirchhoff rod-based dynamical modeling approach, the magneto-elastic rod model, to simulate magnetic guidewire, which provides accurate simulations for two- and three-dimensional dynamic deflections induced by external magnetic fields and obtains deformed guidewire shapes in quasi-static status. Results: The proposed model is capable of describing the intrinsic principles of elastic body actuation by torques generated from the hard-magnetic soft matrix. The effectiveness of the developed model is validated, and the real-time simulation application is conducted via the semi-implicit numerical integration method. Conclusions: It has been shown that the presented dynamical model captures large nonlinear deformations and transient responses of the magnetic guidewire in an imitated human blood environment, which could offer robust support for the construction of a simulated magnetically driven surgical system.

Magnetic guidewire steering at ultrahigh magnetic fields.

With remote magnetic steering capabilities, magnetically actuated guidewires have proven their potential in minimally invasive medical procedures. Existing magnetic steering strategies, however, have been limited to low magnetic fields, which prevents the integration into medical systems operating at ultrahigh fields (UHF), such as magnetic resonance imaging (MRI) scanners. Here, we present magnetic guidewire design and steering strategies by elucidating the magnetic actuation principles of permanent magnets at UHF. By modeling the uniaxial magnetization behavior of permanent magnets, we outline the magnetic torque and force and demonstrate unique magnetic actuation opportunities at UHF, such as in situ remagnetization. Last, we illustrate the proposed steering principles using a magnetic guidewire composed of neodymium magnets and a fiber optic rod in a 7-Tesla preclinical MRI scanner. The developed UHF magnetic actuation framework would enable next-generation magnetic robots to operate inside MRI scanners.

Electromagnetic Manipulation System for Semi-Autonomous Control of Small-Scale Magnetic Objects With Sequential Programming

In this study, an electromagnetic coil system was developed for semi-autonomous manipulation of microrobots in three-dimensional (3D) space with sequential programming. Cylindrical-shaped cores were used for the electromagnetic coils; the coils were arranged in a hemispherical configuration to allow open access to the workspace for imaging tools. The system consisted of four main parts: the electromagnetic coils, an electronic control unit, optical cameras, and a direct-manipulation graphical user interface (GUI). The system was capable of producing a magnetic field of up to 18 mT with a maximum current of 8 A current. Using this system, magnetic force and torque can be applied for semi-autonomous manipulation of magnetic objects, with different time intervals, by instantly inputting the required fields and gradients via the GUI. Sequential programming of the magnetic field allowed for better controllability and enhanced the repeatability of the system. The versatility of the system was demonstrated by moving a magnetic guidewire, micromagnet, and nanoparticles to their intended targets to assess the potential application of the system in biomedical fields.

MP14-19 MAGNETIC CLEARANCE OF KIDNEY STONE FRAGMENTS: INITIAL IN VITRO EXPERIENCE

You have accessJournal of UrologyCME1 May 2022MP14-19 MAGNETIC CLEARANCE OF KIDNEY STONE FRAGMENTS: INITIAL IN VITRO EXPERIENCE Tianjia Jessie Ge, Timothy Chang, Kathy Mach, Shan Wang, Kunj Sheth, Simon Conti, and Joseph Liao Tianjia Jessie GeTianjia Jessie Ge More articles by this author , Timothy ChangTimothy Chang More articles by this author , Kathy MachKathy Mach More articles by this author , Shan WangShan Wang More articles by this author , Kunj ShethKunj Sheth More articles by this author , Simon ContiSimon Conti More articles by this author , and Joseph LiaoJoseph Liao More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002543.19AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Surgical management of stone disease aims for complete clearance. Residual stone fragments are associated with more complications, yet only 60-75% of ureteroscopic treatments achieve complete stone-free status. While residual fragments <2 mm in size are commonly deemed insignificant, up to 30% patients with “clinically insignificant fragments” experience stone-related complications. We propose a system to improve stone-free rates and surgical efficiency, in which fragments are rendered superparamagnetic and retrieved en masse with a magnetic guidewire. METHODS: Human kidney stone fragments obtained from lithotripsy (calcium phosphate (CaPO4), calcium oxalate monohydrate (CaOxM), uric acid, and struvite) were separated by size. Fragments (10-15 mg by dry weight) were rehydrated with normal saline and incubated with superparamagnetic iron oxide particles (range 7 nm to 4.5 µm diameter) possessing carboxylic acid surface chemistry for 3 minutes at 37C. A magnetic guidewire was fabricated from individual magnets within a plastic sheath (0.75 mm total diameter) and captured magnetically labeled fragments along its length in vitro. The fragments were dried and weighed to determine the capture efficiency. The speed of fragment retrieval was compared between the magnetic system and a conventional basket. RESULTS: The magnetic system cleared small fragments (<1 mm) up to twenty times faster than a standard basket in our in vitro experiments. The 7 nm nanoparticle, ferumoxytol, is FDA-approved for the treatment of iron deficiency anemia, and performed satisfactorily in capturing small calcium phosphate fragments. Larger 1 micron particles performed more consistently across different stone compositions. Capture efficiency decreases with increasing stone fragment size, owing to larger gravitational forces counteracting the magnetic attraction. CONCLUSIONS: Iron oxide particles with carboxylic acid surface chemistries, including an FDA-approved nanoparticle, bind to a variety of calcium-based kidney stones. This approach can facilitate the efficient magnetic retrieval of small stone fragments which are difficult to basket, and lead to improved stone-free rates. Further optimization of particle chemistry and magnetic forces will allow for capture of larger fragments and clinical translation. Source of Funding: Stanford Coulter Translational Grant, NIH R21 DK131776 © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e240 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Tianjia Jessie Ge More articles by this author Timothy Chang More articles by this author Kathy Mach More articles by this author Shan Wang More articles by this author Kunj Sheth More articles by this author Simon Conti More articles by this author Joseph Liao More articles by this author Expand All Advertisement PDF DownloadLoading ...

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.

Development of a Magnetic Kissing Guidewire and Animal Experiment: a Preliminary Study

Endovascular therapy has been the first option for many vascular diseases. Due to the increasing development of endovascular devices and techniques in recent decades, endovascular procedures could be applied in treating those cases with complex anatomy. Two or three vascular access routes are required to establish through-and-through access in endovascular therapy for arterial occlusive disease and complex aortic aneurysm. Guidewire snaring with a snare kit is essential but sometimes time-consuming in the establishment of through-and-through access. To simplify the procedure, we design the magnetic kissing guidewire (MKG) with a magnetic tip that attracts each other to establish a guidewire route that meets the needs of clinical practice. We conducted the in vitro test to evaluate its magnetic force and the in vivo test to assess its performance in the arteries of twelve sheep. The results revealed that this novel guidewire significantly simplified the establishment of through-and-through access.

In vivo demonstration of magnetic guidewire steerability in a MRI system with additional gradient coils.

To assess the ability to control the steering of a modified guidewire actuated by the magnetic force of a magnetic resonance imaging system with additional gradient coils for selective arterial catheterization in rabbits. Selective catheterizations of the right renal artery, left renal artery, superior mesenteric artery, and iliac artery were performed on two rabbits. A 3D magnetic force was applied onto a magnetic bead placed at the tip of a guidewire. The ability of the guidewire to advance in the aorta without entering the side branches when the magnetic force was not applied was also evaluated. Steering of the guidewire was combined with a dedicated tracking system and its position was registered on the 3D model of a magnetic resonance angiography (MRA). The magnetic catheterization of the renal arteries was successful and showed reproducibility. Superior mesenteric artery and iliac artery showed that the catheterization was feasible. These two arteries were difficult to visualize on MRA, making catheterization and setting the direction of the force more difficult. There was no inadvertent catheterization of side vessels when the guidewire was advanced with magnetic steering despite the hook shape at the tip of the guidewire caused by the alignment of the bead anisotropy with the permanent magnetic field. This first evaluation of selective catheterization of aortic branches with a magnetic guidewire provided a successful steering in the less angled side branches and this modified guidewire was advanced in the aorta without inadvertent selective catheterization when manipulated without magnetic actuation.

Magnetic navigation system assisted stenting of coronary bifurcation lesions

Magnetic guidewire assisted percutaneous coronary interventions (MPCI) could have certain advantages in coronary bifurcation lesions. We aimed to report the angiographic characteristics of the bifurcation lesions, as well as the procedural and clinical outcomes of the MPCI patients. The lesion characteristics and the treatment effect were assessed by performing diagnostic and quantitative coronary angiography with dedicated bifurcation software. A total of 76 patients (age 65 years, 78% male) were assigned to undergo MPCI, in which two-thirds of the lesions were located in LAD/D1. Fifty-seven out of 78 lesions (73%) had a diseased side branch and complex stenting techniques were used in the majority of the lesions (64%). All 59/78 (76%) fenestration attempts were successfully performed and only 13 dedicated bifurcation stents were implanted. The average acute gain in minimal luminal diameter was 1.08±0.81 mm, 0.80±0.70 mm and 0.59±0.56 mm for the proximal, distal and side branch, respectively. The procedural success was 69% with a procedure time of 107±43 minutes, fluoroscopy time of 34±24 minutes and contrast use of 338±136 ml. At a mean of 1.8-years follow-up, 15 patients (20%) had a cardiac event. MPCI is associated with good angiographic, fenestration and procedural success rates in the treatment of coronary bifurcation lesions.

The feasibility and safety of applying the Magnetic Navigation System to manage chronically occluded vessels: a single centre experience

Applying the Magnetic Navigation System (MNS) to manage chronic total occlusions (CTOs). The MNS precisely directs a magnetised guidewire in vivo through two permanent external magnets. The first 43 consecutive MNS treated CTOs were retrospectively evaluated. Computed tomography coronary angiography (CTCA) co-integration with the MNS provided a virtual road map through the occlusion. Unsuccessful MNS cases were managed with bailout conventional guidewire techniques. Experienced CTO and MNS operators had unrestricted access to CTO devices and equipments. The MNS crossing success increased from 40% to 56% over 52 months and averaged 44.2% (19/43 patients). In 58.3% (14/24) of failed MNS cases the conventional wire approach was successful, giving an overall procedural success rate of 76.6%. Of those conventionally treated, two patients required pericardiocentesis. On average, 1.8 ± 0.9 stents (lengths 44.7 ± 21.4 mm and diameter 2.8 ± 0.4 mm) were implanted. Procedural times were lengthy (125.0 ± 35.3 min) requiring high fluoroscopy dosage (11980.2 ± 6457.9 Gy/cm2) and contrast media usage (388.8 ± 170.2 ml). Operators persevered less with magnetic wires (20.9 ± 12.4 min vs. 27.7 ± 24.4 min), and preferentially used the least stiff wire as first choice (53.5%). CTCA co-integration did not influence procedural outcome. As with conventional wires, higher magnetic wire successes occurred in low calcified lesions, those with a central stump and without bridging collaterals. In unselected CTOs, the magnetic wires are safe and feasible. Current modest success rates with a high procedural bailout rate implicate the need for improved magnetic guidewire technology comparable to available sophisticated conventional CTO wires. Randomised studies are needed to clarify the value of magnetic guided recanalisation.

Primary percutaneous coronary intervention by magnetic navigation compared with conventional wire technique

Aims Comparison of magnetic guidewire navigation in percutaneous coronary intervention (MPCI) vs. conventional percutaneous coronary intervention (CPCI) for the treatment of acute myocardial infarction. Methods and results We compared 65 sequential patients (mean age 61 ± 15 years) undergoing primary MPCI with those of 405 patients undergoing CPCI (mean age 61 ± 13 years). The major endpoint was contrast media use. Technical success and procedural outcomes were evaluated. Clinical demographics and angiographic characteristics of the two groups were similar, except for fewer patients with previous coronary artery bypass grafting (CABG) and hypertension in the CPCI group and fewer patients with diabetes in the MPCI group. The technical success rate was high in both the MPCI and CPCI groups (95.4 vs. 98%). There was significantly less contrast media usage in the MPCI compared with the CPCI group, median reduction of contrast media of 30 mL with an OR = 0.41 (0.21-0.81). Fluoroscopy times were significantly reduced for MPCI compared with CPCI, median reduction of 7.2 min with an OR = 0.42 (0.20-0.79). Conclusion This comparison indicates the feasibility and non-inferiority of magnetic navigation in performing primary PCI and suggests the possibility of reductions in contrast media use and fluoroscopy time compared with CPCI.

Initial experience with remote magnetic navigation for left ventricular lead placement

Background — A novel magnetic navigation system allows remote steering of guidewires and catheters.This system may be used for left ventricular lead placement for cardiac resynchronization therapy (CRT).We sought to evaluate the feasibility and safety of magnetic guidewire navigation for CRT procedures.Methods — 123 consecutive patients underwent CRT implantation/revision procedures (including pacemaker upgrades in n = 22 and left ventricular lead placement after dislocation in n = 4 patients). Left ventricular lead placement in a coronary sinus side branch was performed either conventionally or using magnetic navigation. The magnetic navigation system (Niobe) consists of two permanent magnets creating a steerable magnetic field. Guidewires with integrated magnets align to the magnetic field and were used for over-the-wire implantation of pacemaker leads in the coronary sinus. Patients were assigned to conventional (n = 93) or magnetic (n = 30) navigation according to room availability.Venography of the coronary venous system was performed to select a target vessel for lead implantation.Results — Guidewire access to the target vessel was achieved in 100% using magnetic navigation compared to 87% with the conventional approach (P < 0.05). Implantation success rates, total procedure and fluoroscopy times did not differ significantly between groups. No periprocedural death and no intraoperative device dysfunction occurred in either group.The magnetic guidewire ruptured in one patient.Conclusion — Left ventricular lead placement using magnetic guidewire navigation to engage the desired coronary sinus side branch can be successfully performed for CRT.

Comparison of magnetically navigated and conventional wire percutaneous coronary intervention of a single discrete stenosis

The objective of this study is to compare magnetic guidewire navigation in percutaneous coronary intervention (MPCI) to conventional percutaneous coronary intervention (CPCI) for the elective treatment of a single discrete stenosis. Magnetic navigation actively steers an angioplasty wire-tip and may improve PCI procedures, but it is not known whether the intricacy and increased preparation necessary for using the system negatively influences the performance of simple procedures in terms of time and contrast use. The procedures of 44 patients (mean age 65 +/- 10 year) undergoing elective single vessel MPCI of a single discrete stenosis were matched for age, gender, and lesion location with 44 concurrent patients (mean age 65 +/- 10 year) undergoing CPCI. The major endpoint was procedural time. Technical success was defined as an intraluminal wire position distal to the stenosis. Procedural outcome, contrast use, and costs were evaluated. Clinical demographics and angiographic characteristics of the two groups were similar, except for a higher incidence of previous MI and class III angina pectoris in the conventional group. The technical success rate was high and identical in both groups (97.7%). Procedural and fluoroscopy times were not significantly different for MPCI compared to CPCI (21.0 +/- 14.5 min vs. 24.7 +/- 14.0 min; 4.9 +/- 4.8 min vs. 7.3 +/- 10.3 min, P = NS). There was a significant reduction in median contrast use [60 ml/patient (41-100) vs. 100 ml/patient (64-130); P = 0.006]. Magnetic navigation does not increase procedural time, irradiation, equipment use, or cost compared to conventional PCI of a single discrete stenosis. It proved feasible, yielding high rates of procedural success with less contrast use.

Use of magnetic guidewire navigation in the treatment of lower extremity peripheral vascular disease: Report of the first human clinical experience

The use of a magnetic navigation system (MNS) to facilitate catheter placement in electrophysiologic procedures has been increasingly documented over the past decade. Recently, the utilization of MNS to aid guidewire directionality in complex coronary lesions has also been described. Given the multifaceted ability of MNS to be applied to varying vascular beds, we describe the successful employment of this modality to facilitate treatment of lower extremity peripheral arterial disease in a symptomatic male with gangrenous toe ulceration.

Magnetically navigated percutaneous coronary intervention in distal and/or complex lesions may improve procedural outcome and material consumption

Comparison of magnetic guidewire navigation in percutaneous coronary intervention (magnetic PCI) across distal and/or complex lesions versus conventional navigation (conventional PCI). Forty-seven consecutive patients (age 61 +/- 10 yr) undergoing elective single vessel magnetic PCI for distal and/or complex lesions were matched by age and lesion location with 45 patients undergoing conventional PCI (age 63 +/- 10 yr). Technical success rate was defined as an intraluminal wire position distal to the stenosis. Procedural outcome and costs were evaluated. Baseline demographics and angiographic characteristics of the two groups were similar. The technical success rate did not differ between magnetic and conventional PCI (95.7 vs 97.8%; p = 1.00). Significantly shorter procedural and fluoroscopy time were observed for magnetic compared to conventional PCI (29.9 +/- 17.6 vs 41.1 +/- 21 min, p = 0.007; 7.5 +/- 7.3 vs 16.1 +/- 22.4 min, p = 0.02 respectively). Less contrast was used in the magnetic PCI group (58 ml/patient; P = 0.02). These advantages resulted in a mean estimated saving of 1400 euro per patient (P < 0.001). Advantages of procedural outcome were even more pronounced in the ACC/AHA lesion class C subgroup. Magnetic compared to conventional PCI is an attractive novel technique that proved to be feasible and safe and might be faster in distal and especially complex lesions.

Magnetically guided left ventricular lead implantation based on a virtual three-dimensional reconstructed image of the coronary sinus

AimsLeft ventricular (LV) lead implantation is feasible using remote magnetic navigation of a guidewire (Stereotaxis, St Louis, MO, USA). A novel software that performs a three-dimensional (3D) reconstruction of vessels based on two or more angiographic views has been developed recently (CardiOp-B system™, Paeion Inc., Haifa, Israel). The objective of this paper is to evaluate: (i) the performance of the 3D reconstruction software which reproduce the anatomy of the coronary sinus (CS) and (ii) the efficacy of remotely navigating a magnetic guidewire within the CS based on this reconstruction.Methods and resultsIn patients undergoing cardiac resynchronization therapy implantation, a 3D reconstruction of the CS was performed using the CardiOp-B™ system. Accuracy of the reconstruction was evaluated by comparing with the CS angiogram. This reconstruction was imported into the Stereotaxis system. On the basis of the reconstruction, magnetic vectors were automatically selected to navigate within the CS and manually adjusted if required. Feasibility of deploying the guidewire and LV lead into the selected side branch (SB), fluoroscopy time (FT) required for cannulation of the target SB, and total FT were also evaluated. Sixteen patients were included. In one case, the software could not reconstruct the CS. The quality of the reconstruction was graded as good in 13 and poor in 2. In 10 cases, manual adjustments to the traced edges of the CS were required to perform the 3D reconstruction, and in 5, no adjustments were required. In 13 patients, the target SB was engaged on the basis of the automatically selected vectors. In two cases, manual modification of the vector was required. Mean total FT was 23 ± 14 min and the FT required to cannulate the target SB was 1.7 ± 1.3 min.ConclusionA 3D reconstruction of the CS can be accurately performed using two angiographic views. This reconstruction allows precise magnetic navigation of a guidewire within the CS.

Magnetic‐Guided Percutaneous Coronary Intervention Enabled by Two‐Dimensional Guidewire Steering and Three‐Dimensional Virtual Angioscopy: Initial Experiences in Daily Clinical Practice

Percutaneous coronary intervention (PCI) has been broadly established and often includes highly complex stenoses that require difficult navigation. The purpose of this study is to assess the feasibility of a new magnetic navigation system (MNS) to enable intracoronary guidewire deployment and PCI in daily clinical practice and to compare the 2D guidance to the virtual 3D angioscopy feature. We included 30 consecutive patients (pt) in whom 36 coronary arteries were PCI targets. Patients were randomized to guidewire steering by either 2D guidance or virtual 3D angioscopy (33%). In 31/36 (86%) interventions the MNS guidewire successfully passed the culprit stenosis and the procedure was accomplished by PCI. In 5/30 pt an MNS multivessel intervention was performed. Three of 5 unsuccessful procedures failed due to an unsuccessful recanalization of a subtotal chronic occlusion including 1 pt who required surgical intervention. In 2/36 procedures the magnetic guided intervention was performed effectively after prior conventional failure related to complex anatomy. The contrast medium amount needed to position the magnetic guidewire was 60 +/- 101 mL in 2D accomplished interventions vs. 14 +/- 15 mL in 3D procedures (p < 0.05). In 3 pt the MNS did not harm the implanted pacemaker or defibrillator system. Magnetic guided PCI is useful in selected patients. In our experience, success is less likely in evidence of a subtotal occlusion.

Magnetic Guide-Wire Navigation in Pulmonary and Systemic Arterial Catheterization: Initial Experience in Pigs

Cardiovascular catheterization can be challenging whenever a stenosis or an abnormal vascular course interferes with probing the target vessel. This study addresses the feasibility of navigating a guide wire with a magnetic tip by an external magnetic field through pulmonary and systemic arteries in an experimental porcine model. We investigated six piglets using magnetic guide-wire navigation. Two pulmonary arteriograms were taken from different angles in order to reconstruct the three-dimensional vessel anatomy. A computer interface then calculated three-dimensional coordinates for the vessel in space. Using these coordinates, two external magnets were positioned to create magnetic vectors along the expected vessel course. Magnetically enabled guide wires were then navigated into the vessels using the magnetic field to orient the guide-wire tips. Aortic and renal branches were addressed in a similar fashion. Difficulty in reaching the target vessel was reflected by the number of attempts that were necessary. After 10 failed attempts, the maneuver was recorded to have failed. Thirty-five of 37 (94.6%) arteries with branches at acute angles were reached successfully using magnetic navigation. In two pigs, the left upper lobe artery could not be probed. Peripheral arteries of small diameter were easier to reach than large central arteries, requiring less attempts. Magnetic guide-wire navigation is feasible in the arteries of the lungs, the head and neck, and the kidneys. It is particularly useful in entering small arterial branches at acute angles and may facilitate interventional therapy in a variety of vascular diseases in children and adults.

Magnetically assisted biventricular device implantation: Comparison using a standard guidesheath or a “bare” wire approach without a guidesheath

Background: Biventricular (BiV) devices have been shown to significantly benefit patients with electro-mechanical dyssynchrony and severe heart failure. The implantation of BiV devices remains technically challenging and the selection of lateral coronary sinus (CS) branch vessels can be time consuming. This study is the first to evaluate the initial experience using magnetic navigation and a magnetic guidewire in the implantation of BiV devices using either a traditional CS guidesheath or a “bare” wire (no CS guidesheath).