Catheter Movement Research Articles

Intuitive Control Strategies for Teleoperation of Active Catheters in Endovascular Surgery

Cardiovascular surgeons increasingly resort to catheter-based diagnostic and therapeutic interventions because of their limited invasiveness. Although, these approaches allow treatment of patients considered unfit for conventional open surgery, exposure to radiation and high procedural complexity could lead to complications. These factors motivated the introduction of robotic technology offering more dexterous catheters, enhanced visualization and opening new possibilities in terms of guidance and coordinated control. In addition to improvements of patient outcome, through teleoperated catheter control radiation exposure of surgeons can be reduced. In order to limit surgical workload, intuitive mappings between joystick input and resulting catheter motion are essential. This paper presents and compares two proposed mappings and investigates the benefits of additional visual guidance. The comparison is based on data gathered during an experimental campaign involving 14 novices and three surgeons. The participants were asked to perform an endovascular task in a virtual reality simulator presented in the first part of this paper. Statistical results show significant superiority of one mapping with respect to the other and a significant improvement of performance thanks to additional visual guidance. Future work will focus on translating the results to a physical setup for surgical validation, also the learning effect will be analyzed more in-depth.

부정맥 시술을 위한 마스터-슬레이브 원격제어·로봇 시스템 개발

Recently, the robotic assist system for cardiovascular intervention gets continuously growing interest. The robotic cardiovascular intervention systems are largely two folds, systems for cardiac ablation procedure assist and systems for vascular intervention assist. For the systems, the clinician controls the catheter inserted through blood vessel to the heart via a master console or master manipulator. Most of the current master manipulators have structure of joystick-like pivoting 2 degree of freedom (DOF) handle in the core, which is used in parallel with other sliding switches and input devices. It however is desirable to have customized and optimized design manipulator that can provide clinician with intuitive control of the catheter motion fully utilizing the advantage of the use of robotic structure. A 6 DOF kinematic mechanism that can capture the motion control intention of the clinician in translational 3 DOF and rotational 3 DOF is proposed in this paper. Also, a master-slave motion relationship specially designed for the cardiac catheter manipulation motion is proposed and implemented in an experimental prototype. Design revision for implementation of more efficient motion and experiment in combination with an experimental slave robot system for catheter manipulation are underway.

SCEM+: Real-Time Robust Simultaneous Catheter and Environment Modeling for Endovascular Navigation

Endovascular procedures are characterised by significant challenges mainly due to the complexity in catheter control and navigation. Real-time recovery of the 3-D structure of the vasculature is necessary to visualise the interaction between the catheter and its surrounding environment to facilitate catheter manipulations. State-of-the-art intraoperative vessel reconstruction approaches are increasingly relying on nonionising imaging techniques such as optical coherence tomography (OCT) and intravascular ultrasound (IVUS). To enable accurate recovery of vessel structures and to deal with sensing errors and abrupt catheter motions, this letter presents a robust and real-time vessel reconstruction scheme for endovascular navigation based on IVUS and electromagnetic (EM) tracking. It is formulated as a nonlinear optimisation problem, which considers the uncertainty in both the IVUS contour and the EM pose, as well as vessel morphology provided by preoperative data. Detailed phantom validation is performed and the results demonstrate the potential clinical value of the technique.

Evaluation of esophageal distensibility in eosinophilic esophagitis: an update and comparison of functional lumen imaging probe analytic methods.

Distensibility evaluation of the esophageal body using the functional lumen imaging probe (FLIP) offers an objective measure to characterize patients with eosinophilic esophagitis (EoE), though this analysis may be limited by unrecognized catheter movement and esophageal contractility. The aims of this study were to report novel FLIP analytic methods of esophageal distensibility measurement in EoE and to assess the effect of contractility. Nine healthy controls (six female; ages 20-49) and 20 EoE patients (four female; ages 19-64; grouped by degree of distension-mediated contractility identified on FLIP) were evaluated with a 16-cm FLIP device during step-wise balloon distension during upper endoscopy. A distensibility plateau (DP) was generated using multiple methods to identify the narrowest esophageal body diameter: (i) wavelet decomposition (WD), (ii) maximal diameter (MD), and (iii) FLIP Analytics software. Distensibility was reduced in EoE patients compared with controls using the WD (p = 0.002) and MD (p = 0.001) methods; a trend was detected using the FLIP Analytics method (p = 0.055). Significant intra-subject differences were detected between methods among both patients and controls (p-values <0.001 to 0.025); the difference was more pronounced among subjects with a greater degree of contractility. DP was <19 mm among 7/9 controls with FLIP Analytics, 6/9 controls with WD, and 0/9 controls using the MD method. Distension-mediated contractility affects distensibility measurement with the FLIP. Using software-based algorithms, particularly with a method that identifies the maximal-achieved diameters (MD), may improve objective distensibility measurement for clinical research and practice.

Flexible robotics with electromagnetic tracking improves safety and efficiency during in vitro endovascular navigation

One limitation of the use of robotic catheters is the lack of real-time three-dimensional (3D) localization and position updating: they are still navigated based on two-dimensional (2D) X-ray fluoroscopic projection images. Our goal was to evaluatewhether incorporating an electromagnetic (EM) sensor on a robotic catheter tip could improve endovascular navigation. Six users were tasked to navigate using a robotic catheter with incorporated EM sensors in an aortic aneurysm phantom. All users cannulated two anatomic targets (left renal artery and posterior "gate") using four visualization modes: (1) standard fluoroscopy mode (control), (2) 2D fluoroscopy mode showing real-time virtual catheter orientation from EM tracking, (3) 3D model of the phantom with anteroposterior and endoluminal view, and (4) 3D model with anteroposterior and lateral view. Standard X-ray fluoroscopy was always available. Cannulation and fluoroscopy times were noted for every mode. 3D positions of the EM tip sensor were recorded at 4Hz to establish kinematic metrics. The EM sensor-incorporated catheter navigated as expected according to all users. The success rate for cannulation was 100%. For the posterior gate target, mean cannulation times in minutes:seconds were 8:12, 4:19, 4:29, and 3:09, respectively, for modes 1, 2, 3 and 4 (P= .013), and mean fluoroscopy times were 274, 20, 29, and 2seconds, respectively (P= .001). 3D path lengths, spectral arc length, root mean dimensionless jerk, and number of submovements were significantly improved when EM tracking was used (P< .05), showing higher quality of catheter movement with EM navigation. The EM tracked robotic catheter allowed better real-time 3D orientation, facilitating navigation, with a reduction in cannulation and fluoroscopy times and improvement of motion consistency and efficiency.

A novel model of epidural catheter-related infection: the importance of repeated catheter movements

A novel model of epidural catheter-related infection: the importance of repeated catheter movements

Remote Magnetic Navigation: A Focus on Catheter Ablation of Ventricular Arrhythmias.

VT ablation is based on percutaneous catheter insertion under fluoroscopic guidance to selectively destroy (i.e., ablate) myocardial tissue regions responsible for the initiation or propagation of ventricular arrhythmias. Although the last decade has witnessed a rapid evolution of ablation equipment and techniques, the control over catheter movement during manual ablation has remained largely unchanged. Moreover, the procedures are long, and require ergonomically unfavorable positions, which can lead to operator fatigue. In an attempt to overcome these constraints, several technical advancements, including remote magnetic navigation (RMN), have been developed. RMN utilizes a magnetic field to remotely manipulate specially designed soft-tip ablation catheters anywhere in the x, y, or z plane inside the patient's chest. RMN also facilitates titration of the contact force between the catheter and the myocardial tissue, which may reduce the risk of complications while ensuring adequate lesion formation. There are several non-randomized studies showing that RMN has similar efficacy to manual ablation, while complication rates and total radiation exposure appears to be lower. Although these data are promising, larger randomized studies are needed to prove that RMN is superior to manual ablation of VT.

Hybrid Imaging in the Catheter Laboratory: Real-time Fusion of Echocardiography and Fluoroscopy During Percutaneous Structural Heart Disease Interventions

Percutaneous catheter-based techniques for the treatment of structural heart disease are becoming more complex, and current imaging techniques have limitations: while fluoroscopy gives poor visualisation of cardiac anatomical structures, echocardiography is limited in its ability to detect the position of catheters and devices. The EchoNavigator® (Philips) live image guidance tool is a novel system that integrates real-time echocardiography with fluoroscopic X-ray imaging, optimising the guidance and positioning of devices. Use of the EchoNavigator system facilitates improved understanding of anatomical structures while showing enhanced visualisation of catheter and device movements. Early clinical experience suggests that the technology is feasible and safe, and provides enhanced understanding of the relationship between soft tissue anatomy and catheter devices in structural heart disease. The use of the EchoNavigator system can improve the confidence of interventional cardiologists in the targeting and positioning of devices in percutaneous interventions in structural heart disease, and has the potential to reduce procedural time, reduce the dosage of contrast and radiation and increase safety in the performance of procedural steps.

Hybrid Imaging in the Catheter Laboratory: Real-time Fusion of Echocardiography and Fluoroscopy During Percutaneous Structural Heart Disease Interventions.

Percutaneous catheter-based techniques for the treatment of structural heart disease are becoming more complex, and current imaging techniques have limitations: while fluoroscopy gives poor visualisation of cardiac anatomical structures, echocardiography is limited in its ability to detect the position of catheters and devices. The EchoNavigator® (Philips) live image guidance tool is a novel system that integrates real-time echocardiography with fluoroscopic X-ray imaging, optimising the guidance and positioning of devices. Use of the EchoNavigator system facilitates improved understanding of anatomical structures while showing enhanced visualisation of catheter and device movements. Early clinical experience suggests that the technology is feasible and safe, and provides enhanced understanding of the relationship between soft tissue anatomy and catheter devices in structural heart disease. The use of the EchoNavigator system can improve the confidence of interventional cardiologists in the targeting and positioning of devices in percutaneous interventions in structural heart disease, and has the potential to reduce procedural time, reduce the dosage of contrast and radiation and increase safety in the performance of procedural steps.

Design and fabrication of a catheter magnetic navigation system for cardiac arrhythmias

In the past decade, remotely controlled catheter ablation has emerged as a novel approach to reduce fluoroscopy exposure and provide stable and reproducible catheter movement during cardiac surgeries for arrhythmias, and many groups have obtained very promising achievements in this research field. Meanwhile, the catheter magnetic navigation system (MNS) is very competitive among these catheter navigation systems since there are no moving parts in the magnet system. A catheter MNS that provides real-time navigation of the catheter in the beating heat is under development in the Institute of Electrical Engineering, Chinese Academy of Sciences. The catheter navigation system consists of eight spherically aligned electromagnets that generate the dynamically shaped magnetic field around the torso of the subject, eight four-phase high-current power supplies that excite the eight electromagnets to generate the needed magnetic field in time, and programmed magnetic navigation software that transfers the control signal to the electromagnets on the basis of the designated directions given by the joystick. The real-time shaping of the magnetic field functions for the 3-D direction change of a magnetized electrophysiology ablation catheter in the beating heart. EnSite-NavX™ 3-D electroanatomic mapping system is employed to integrate with the MNS. Detailed design, fabrication, and test of the remotely controlled MNS (RCMNS) are mainly introduced herein, and preliminary study on animals using RCMNS is on the way.

Magnetic resonance imaging compatible remote catheter navigation system with 3 degrees of freedom.

To facilitate MRI-guided catheterization procedures, we present an MRI-compatible remote catheter navigation system that allows remote navigation of steerable catheters with 3 degrees of freedom. The system consists of a user interface (master), a robot (slave), and an ultrasonic motor control servomechanism. The interventionalist applies conventional motions (axial, radial and plunger manipulations) on an input catheter in the master unit; this user input is measured and used by the servomechanism to control a compact catheter manipulating robot, such that it replicates the interventionalist's input motion on the patient catheter. The performance of the system was evaluated in terms of MRI compatibility (SNR and artifact), feasibility of remote navigation under real-time MRI guidance, and motion replication accuracy. Real-time MRI experiments demonstrated that catheter was successfully navigated remotely to desired target references in all 3 degrees of freedom. The system had an absolute value error of [Formula: see text]1mm in axial catheter motion replication over 30mm of travel and [Formula: see text] for radial catheter motion replication over [Formula: see text]. The worst case SNR drop was observed to be [Formula: see text]3%; the robot did not introduce any artifacts in the MR images. An MRI-compatible compact remote catheter navigation system has been developed that allows remote navigation of steerable catheters with 3 degrees of freedom. The proposed system allows for safe and accurate remote catheter navigation, within conventional closed-bore scanners, without degrading MR image quality.

Dose Intraoperative Fluoroscopy Precisely Predict Catheter Tip Location via Superior Vena Cava Route?

Adequate catheter tip location is crucial for functional intravenous port and central venous catheter. Numerous complications were reported because of catheter migration that caused by inadequate tip location. Different guidelines recommend different ideal locations without consensus. Another debate is actual movement of intravascular portion of implanted catheter. From literature review, the catheter migrated peripherally an average of 20 mm on the erect chest radiographs. In this study, we want to verify the actual presentation of catheter movement within a vessel and try to find a quantitative catheter length model to recommend.From March 2012 to March 2013, 346 patients were included into this prospective cohort study. We collect clinical data from medical record and utilized picture archiving and communication system to measure all image parameters. Statistical analysis was utilized to identify the risk factors for catheter migration.The nonmigration group had 221 patients (63.9%); 67 (19.4%) patients were classified into the peripheral migration group; and 58 (16.8%) patients were classified into the central migration group. Patients with short height (P = 0.03), larger superior vena cava (SVC) diameters at the brachiocephalic vein confluence site (P = 0.02), and longer implanted catheter length (P = 0.0004) had greater risks for central migration. We utilized regression curve for further analysis and height (centimeters)/10 had moderate correlation distances from the entry vessel to the carina.Although intravascular movement of catheter was exist in implanted catheter, the intraoperative fluoroscopy could provide accurate catheter tip location in 63.9% patients. Additional length of catheter implantation seems unnecessary in 80.6% patients. Patients with short height, larger SVC diameters at the brachiocephalic vein confluence site had greater risk for catheter central movement. Height/10 may be consider as reference length of implantation for inexperience surgeon and precise implantation length could be adjust under guidance of fluoroscopy.

Image-based view-angle independent cardiorespiratory motion gating and coronary sinus catheter tracking for x-ray-guided cardiac electrophysiology procedures

Determination of the cardiorespiratory phase of the heart has numerous applications during cardiac imaging. In this article we propose a novel view-angle independent near-real time cardiorespiratory motion gating and coronary sinus (CS) catheter tracking technique for x-ray fluoroscopy images that are used to guide cardiac electrophysiology procedures. The method is based on learning CS catheter motion using principal component analysis and then applying the derived motion model to unseen images taken at arbitrary projections, using the epipolar constraint. This method is also able to track the CS catheter throughout the x-ray images in any arbitrary subsequent view. We also demonstrate the clinical application of our model on rotational angiography sequences. We validated our technique in normal and very low dose phantom and clinical datasets. For the normal dose clinical images we established average systole, end-expiration and end-inspiration gating success rates of 100%, 85.7%, and 92.3%, respectively. For very low dose applications, the technique was able to track the CS catheter with median errors not exceeding 1 mm for all tracked electrodes. Average gating success rates of 80.3%, 71.4%, and 69.2% were established for the application of the technique on clinical datasets, even with a dose reduction of more than 10 times. In rotational sequences at normal dose, CS tracking median errors were within 1.2 mm for all electrodes, and the gating success rate was 100%, for view angles from RAO 90° to LAO 90°. This view-angle independent technique can extract clinically useful cardiorespiratory motion information using x-ray doses significantly lower than those currently used in clinical practice.

Pain assessment during transradial catheterization using the Visual Analogue Scale

ABSTRACT Background Patients undergoing transradial procedures may experience pain associated with radial artery spasm. The pain can be assessed using the Visual Analogue Scale (VAS), an easy-to-apply, one-dimensional method. This study analyzed the perception of pain using the VAS and correlated it with the perception of spasm by the interventionist. Methods This was an observational, prospective, single-center registry, which included patients undergoing diagnostic or therapeutic transradial procedures. The VAS consists of a 100-mm horizontal line, which has at its extremes the words “no pain” and “unbearable pain”. The patient was instructed to identify the point that represented the perceived pain during the procedure. The interventionist quantified the spasm as zero for no pain, 1 for pain with no resistance to catheter movement, 2 for mild resistance, 3 for moderate resistance, and 4 for intense resistance. Results Pain assessment by patients using the VAS was possible in all patients, and had a mean of 25.5 ± 25.7 mm. For the interventionist, spasm was classified as grade zero in 53 cases (35.8%); grade 1 in 67 (45.3%); grade 2 in 24 (16.2%); grade 3 in 3 (2.0%); and grade 4 in 1 patient (0.7%). Kendall's tau-b and Spearman's (rho) rank correlation coefficients were, respectively, 0.527 and 0.647, showing a moderate positive correlation between the perception of pain by the patient and the perception of spasm by the operator. Conclusions VAS can be used to assess spasm during procedures that use the transradial access, showing a positive correlation with spasm assessment by the interventionist.

Multi-phase rotational angiography of the left ventricle to assist ablations: feasibility and accuracy of novel imaging

Interventional left ventricular (LV) procedures integrating static 3D anatomy visualization are subject to mismatch with dynamic catheter movements due to prominent LV motion. We aimed to evaluate the accuracy of a recently developed acquisition and post-processing protocol for low radiation dose LV multi-phase rotational angiography (4DRA) in patients. 4DRA image acquisition of the LV was performed as investigational acquisition in patients undergoing left-sided ablation (11 men; BMI = 24.7 ± 2.5 kg/m²). Iodine contrast was injected in the LA, while pacing from the RA at a cycle length of 700 ms. 4DRA acquisition and reconstruction were possible in all 11 studies. Reconstructed images were post-processed using streak artefact reduction algorithms and an interphase registration-based filtering method, increasing contrast-to-noise ratio by a factor 8.2 ± 2.1. This enabled semi-automatic segmentation, yielding LV models of five equidistant phases per cardiac cycle. For evaluation, off-line 4DRA fluoroscopy registration was performed, and the 4DRA LV contours of the different phases were compared with the contours of five corresponding phases of biplane LV angiography, acquired in identical circumstances. Of the distances between these contours, 95% were <4 mm in both incidences. Effective radiation dose for 4DRA, calculated by patient-specific Monte-Carlo simulation, was 5.1 ± 1.1 mSv. Creation of 4DRA LV models in man is feasible at near-physiological heart rate and with clinically acceptable radiation dose. They showed high accuracy with respect to LV angiography in RAO and LAO. The presented technology not only opens perspectives for full cardiac cycle dynamic anatomical guidance during interventional procedures, but also for 3DRA without need for very rapid pacing.

Central Venous Catheter Securement: Using the Healthcare and Technology Synergy Model to Take a Closer Look

Proper securement provides a safe vascular access device environment for both patients and health care providers. Successful securement protects central venous catheters from several sources of failure until the end of therapy by preventing central venous catheter movement during all phases of care. Movement causes vein trauma, bacterial migration, distal tip location variation, loss of dressing integrity, and even total dislodgement. Any of these events can have serious consequences, including catheter-related bloodstream infection, thrombosis, delay of treatment, catheter replacement, and potential hemorrhage, all of which can be life-threatening events, and increase costs. We review patient issues, practice issues, and the types of securement currently used in clinical settings.

Kinematics effectively delineate accomplished users of endovascular robotics with a physical training model

Endovascular robotics systems, now approved for clinical use in the United States and Europe, are seeing rapid growth in interest. Determining who has sufficient expertise for safe and effective clinical use remains elusive. Our aim was to analyze performance on a robotic platform to determine what defines an expert user. During three sessions, 21 subjects with a range of endovascular expertise and endovascular robotic experience (novices <2 hours to moderate-extensive experience with >20 hours) performed four tasks on a training model. All participants completed a 2-hour training session on the robot by a certified instructor. Completion times, global rating scores, and motion metrics were collected to assess performance. Electromagnetic tracking was used to capture and to analyze catheter tip motion. Motion analysis was based on derivations of speed and position including spectral arc length and total number of submovements (inversely proportional to proficiency of motion) and duration of submovements (directly proportional to proficiency). Ninety-eight percent of competent subjects successfully completed the tasks within the given time, whereas 91% of noncompetent subjects were successful. There was no significant difference in completion times between competent and noncompetent users except for the posterior branch (151 s:105 s; P = .01). The competent users had more efficient motion as evidenced by statistically significant differences in the metrics of motion analysis. Users with >20 hours of experience performed significantly better than those newer to the system, independent of prior endovascular experience. This study demonstrates that motion-based metrics can differentiate novice from trained users of flexible robotics systems for basic endovascular tasks. Efficiency of catheter movement, consistency of performance, and learning curves may help identify users who are sufficiently trained for safe clinical use of the system. This work will help identify the learning curve and specific movements that translate to expert robotic navigation.

"Chicago classification" should be challenged in the diagnosis of achalasia: heterogeneity of achalasia.

TO THE EDITOR: We read with interest the review article by Lee et al1 regarding “Clinical characteristics and treatment outcomes of 3 subtypes of achalasia according to the Chicago classification in a tertiary institute in Korea.” The study showed that type II achalasia (n = 28 [50.9%]) is the most common subtype followed by type I (n = 21 [38.2%]) and type III (n = 6 [10.9%]). Interestingly, all type III patients responded to calcium channel blocker in the study. The authors suggested that type III should be a different entity from those of type I and II. We strongly agree with their opinion. We have been evaluating patients with suspected achalasia using high-resolution manometry (HRM) with special interest for 5 years. To our experience, the definition of achalasia according to “Chicago classification of HRM” is not perfect. We have experienced achalasia patients with normal integrated relaxation pressure (IRP). As one example, a 12-year-old female who began to experience dysphagia for solid food approximately 2 months before presentation. Physical examination did not reveal signs of scleroderma. Upper endoscopy revealed esophageal dilatation with retained secretion and food material (Fig. 1A and ​and1B).1B). A barium esophagogram showed severe disturbance in emptying into the stomach (Fig. 1C). HRM at sitting position showed aperistalsis with normal 4 second-IRP (normal range < 15 mmHg) (Fig. 1D). Eckardt score at that time was 5. Based on this constellation of data, the patient was diagnosed with achalasia, and underwent peroral endoscopic myotomy. On follow-up at 6 months, she was free of dysphagia, and upper endoscopy revealed unremarkable findings except for scar changes at the site of the mucosal entrance (Fig. 2A and ​and2B).2B). Barium esophagography showed free flow of contrast from the esophagus to the stomach (Fig. 2C). HRM showed weak peristalsis with large peristaltic defects (Fig. 2D). Figure 1. Clinical findings of a 12-year-old female with solid dysphagia. (A) Upper endoscopy shows dilated esophagus and retained food material. (B) Lower esophageal sphincter is not opened with air inflation. (C) Esophageal dilatation with bird-beak narrowing ... Figure 2. The clinical findings of follow-up at 6 months after peroral endoscopic myotomy. (A) Upper endoscopy shows opened lower esophageal sphincter. (B) A scar is visible at the site of the mucosal entrance. (C) Barium esophagogram shows free flow of contrast ... The Chicago classification is challenged by this case of achalasia with normal IRP. In fact, we have experienced 4 patients with achalasia, who were similar to this case. These findings suggested that normal IRP does not preclude a diagnosis of achalasia. Refining the IRP should be needed especially in patients with low lower esophageal sphincter (LES) pressure, although the sitting position might contribute to these atypical findings. Earlier studies of conventional manometry demonstrated that a subset of achalasia patients had apparently normal LES relaxation.2–5 In the past, one plausible explanation for the reason is that it represents an artifact from the movement of manometry catheter. In the era of HRM, the achalasia cases with normal LES relaxation (ie normal IRP) can not be explained by the artifact associated with catheter movement. The findings of achalasia with normal IRP also raise a number of issues regarding the etiopathogenesis of achalasia. The findings might be a representative of an early phase of the achalasia. The relatively short period follow-up (2 months) may support this possible explanation. Interestingly, this case showed transition from achalasia to weak peristalsis after treatment. In conclusion, we should know the significance in the heterogeneity of achalasia, that is not addressed by current “Chicago classification of HRM.”

Electrogram-gated radiofrequency ablations with duty cycle power delivery negate effects of ablation catheter motion.

Cardiac and respiratory movements cause catheter instability. Lateral catheter sliding over target endocardial surface can lead to poor tissue contact and unpredictable lesion formation. We describe a novel method of overcoming the effects of lateral catheter sliding movements using an electrogram-gated pulsed power ablation. All ablations were performed on a thermochromic gel myocardial phantom. Ablation settings were randomized to conventional (nongated) 30 W versus electrogram-gated at 20% duty cycle (30 W average power) at 0-, 3-, 6-, and 9-mm lateral sliding distances. Forty-eight radiofrequency ablations were performed. Deeper lesions were created in electrogram-gated versus conventional ablations at 3 mm (4.36±0.08 versus 4.05±0.17 mm; P=0.009), 6 mm (4.39±0.10 versus 3.44±0.15 mm; P<0.001), and 9 mm (4.41±0.06 versus 2.94±0.16 mm; P<<0.001) sliding distances. Electrogram-gated ablations created consistent lesions at a quicker rate of growth in depth when compared with conventional ablations (P<0.001). (1) Lesion depth decreases and length increases in conventional ablations with greater degrees of lateral catheter movements; (2) electrogram-gated pulsed radiofrequency delivery negated the effects from lateral catheter movement by creating consistently deeper lesions irrespective of the degree of catheter movement; and (3) target lesion depths were reached significantly faster in electrogram-gated than in conventional ablations.

Catheter manipulation training system based on quantitative measurement of catheter insertion and rotation

How to preserve the catheter without any modifications and improve the precision of manipulation in the catheter-based endovascular intervention remains a challenge for quantitative training and evaluation. This paper presents an optical sensor unit to measure catheter motions based on the working principle of Laser Doppler, which allows for catheter motion measurement with non-contact detection and supports medical training and evaluation without modifications on the catheter. Then, calibrate this sensor unit and implement recording of catheter motion. Next, propose a training system by tracking the reference trajectory based on an expert’s skill, and provide visual feedback to improve the precision of catheter manipulation. Eight subjects were trained for catheter manipulation with this system. Among them, six subjects improved their catheter manipulation of linear motion, and seven improved the catheter rotational motion.