Catheter Movement Research Articles

Percutaneous Access of the Epicardial Space for Mapping Ventricular and Supraventricular Arrhythmias in Patients With and Without Prior Cardiac Surgery

There is a paucity of data on the success rates of achieving percutaneous epicardial access in different groups of patients. Percutaneous epicardial access was attempted in 137 patients having 149 procedures; 19 patients had supraventricular tachycardia (SVT), 25 patients had idiopathic VT and 93 patients had scar-related ventricular tachycardia (VT). Ten patients had prior cardiac surgery. Successful epicardial access was achieved in 133 of 149 (89.3%) procedures. Access was achieved in 17 of 19 (89.5%) patients with SVT, all patients with idiopathic VT, 80 of 93 (86.0%) patients with scar-related VT and in 2 (20%) patients with prior cardiac surgery. Attempted access failed in 16 patients; 8 had prior cardiac surgery and 3 had prior pericarditis. After an initial procedure, repeat access was attempted in 15 patients, 5.1 +/- 5.4 months after initial epicardial mapping and ablation. Access was successful in 13 (86.7%) and failed in 2 patients who had pericarditis after their first procedure. Only 4 patients were given intrapericardial glucocorticoid at their first epicardial procedure. Prior cardiac surgery and a history of pericarditis predicted unsuccessful access (P < 0.01). Complications (9 patients) included pericardial bleeding (80-250 mL) and intraabdominal bleeding. In patients without prior cardiac surgery, percutaneous epicardial access can be obtained in the majority of patients. Prior cardiac surgery precludes access in the most patients and when possible adhesions may limit catheter movement. Repeat access is possible in the majority of patients without the installation of intrapericardial glucocorticoid at the first procedure.

Use of the Impella™ Microaxial Blood Pump for Ablation of Hemodynamically Unstable Ventricular Tachycardia

Ablation for ventricular tachycardia remains a challenge with suboptimal procedural success rates. One of the major causes of difficulty is precipitous hypotension when ventricular tachycardia is induced precluding even rapid mapping of the arrhythmia. We report the successful use of the Impella microcirculatory axial blood flow pump in 3 patients with hemodynamically unstable ventricular tachycardia that allowed successful completion of the procedure. In these 3 patients, there was no evidence of Impella-related valvular disturbance, iatrogenic ventricular arrhythmias, or interference with mapping and ablation catheter movement.

Remote‐controlled vascular interventional surgery robot

Conventional vascular interventional surgery (VIS) is manually performed under fluoroscopic guidance, requiring lead protection for the surgeons. A remote-control vascular interventional surgery robot (VISR) which can remotely, safely and precisely perform VIS would have clear advantages. Our robot adopts a master-slave structure. The surgeon sits at the master site, sending controlling instructions to the robot fixed at the slave site, then the robot translates these instructions into catheter motion. The robotic mechanism consists of a supporting manipulator and a catheter navigator; the former adjusts the robot's spatial position, while the latter controls the translation and rotation of the catheter. A 3D vascular model is reconstructed so that the surgeon can perform surgical planning easily. In addition, the tactile force between catheter tip and blood vessel is measured, which prevents the surgeon damaging delicate vessels. In glass model and animal experiments, the surgeon remotely controlled VISR, which inserted a catheter into predefined targets, and the robotic surgery time was measured. The robot was initially tested on a transparent glass vascular model. Under robotic manipulation, the catheter can enter an arbitrary branch of the vascular model and catheter motion can meet the requirements of clinical VIS. Then robotic surgery was performed successfully in an adult dog. Surgery time to access each of the five targets, viz. renal artery, left atrium, right atrium, left ventricle and right ventricle, was measured. Compared with conventional manual surgery, robotic surgery time is a little longer. The experiments show the feasibility and safety of the VISR to facilitate navigation, position precisely and control catheters to specific regions. The VISR system offers surgeon radiation safety and minimizes surgeon-based error.

Development of an In Vitro Tracking System with Poly (vinyl alcohol) Hydrogel for Catheter Motion

Vascular diseases, such as ischemic heart disease, infarction, aneurysms, stroke and stenosis are a leading cause of serious long-term disability and their mortality rate is as high as that of cancers in many countries. Recently, neurovascular intervention using catheters is a minimally-invasive endovascular technique used to treat vascular disease of the brain, and a navigation system for catheters has been developed to facilitate surgical planning and to provide intra-operative assistance. Since the mechanical properties of a catheter play an important role in reaching the targeted disease, tracking of catheter movement during endovascular treatment may be useful to increase confirmation of the rate of successful operation. In this study, we developed an in vitro tracking system for catheter motion using poly (vinyl alcohol) hydrogel (PVA-H) to mimic an arterial wall. The employed models were made of PVA-H, which is sufficiently transparent to permit observation of catheter movement in the artery. This system is expected to contribute to validation of computer-based navigation systems for surgical assistance.

Remote Navigation for Ablation Procedures – A New Step Forward in the Treatment of Cardiac Arrhythmias

Catheter ablation has become the curative treatment for various cardiac arrhythmias, including ventricular tachycardia and atrial fibrillation, leading to more challenging procedures, prolonged fluoroscopy exposure and the need for stable and reproducible catheter movement. In the last decade, remotely-controlled catheter ablation has emerged as a novel concept to improve catheter manoeuvrability and stability. This has the potential to increase procedural success, decrease procedure time and minimise catheter-related complications. To date, two remote navigation systems (Niobe from Stereotaxis and Sensei from Hansen Medical) are commercially available based on magnetic and mechanical driven forces, respectively. Both have shown promise but also shortcomings during clinical evaluation. Recently, two new systems, CGCIMaxwell from Magnetecs and Amigo from Catheter Robotics, have shown promising results in animals. They are under clinical evaluation and are also based on magnetic and mechanical driven forces, respectively. This article describes the basic principles of the systems, summarises their respective published experiences during mapping and ablation procedures, their current clinical applications and future directions.

Use of the Seldinger Type Movement Over a J-Shaped Stylet for Left Ventricular Vent Insertion

Access through the right superior pulmonary vein is a commonly used route for left ventricular vent insertion. Complex reshaping of the stylet and vent into a certain position or external guidance do not guarantee successful placement. In this article we describe a modified technique where the stylet sets up the position to allow consistent atraumatic advancement of the catheter across the mitral valve.

An expandable catheter loop coil for intravascular MRI in larger blood vessels

The present study proposes a catheter system with an expandable coil etched on a polyimide foil. The catheter system combines the advantages of a small insertion diameter when the coil is rolled up in a protective carrier sheath with an increased signal-to-noise ratio (SNR) and penetration depth when the coil is pushed out. After imaging, the coil can be retracted into the sheath and folded back into the initial rolled-up configuration due to the tapered geometry of the carrier foil. The catheter system was tested on two healthy anesthetized pigs, including tracking and high-resolution intravascular imaging. To reduce artifacts in high-resolution images induced by catheter motion in the pulsatile blood flow, a motion-gating method was implemented that combines a flow-compensated two-dimensional fast low angle shot (FLASH) imaging sequence with the acquisition of projection data for retrospective gating. Using the projection data for motion detection, image SNR was increased by up to 500% over uncorrected images, and anatomic structures of 150 microm size could be differentiated in the aorta.

Interactive real-time mapping and catheter ablation of the cavotricuspid isthmus guided by magnetic resonance imaging in a porcine model

AimsWe investigated the feasibility of real-time magnetic resonance imaging (RTMRI) guided ablation of the cavotricuspid isthmus (CTI) by using a MRI-compatible ablation catheter.Methods and resultsCavotricuspid isthmus ablation was performed in an interventional RTMRI suite by using a novel 7 French, steerable, non-ferromagnetic ablation catheter in a porcine in vivo model (n = 20). The catheter was introduced and navigated by RTMRI visualization only. Catheter position and movement during manipulation were continuously visualized during the entire intervention. Two porcine prematurely died due to VT/VF. Anatomical completion of the CTI ablation line could be achieved after a mean of 6.3±3 RF pulses (RF energy: 1807±1016.4 Ws/RF pulse, temperature: 55.9±5.9°C) in n = 18 animals. In 15 of 18 procedures (83.3%) a complete CTI block was proven by conventional mapping in the electrophysiological (EP) lab.ConclusionCompletely non-fluoroscopic ablation guided by RTMRI using a steerable and non-ferromagnetic catheter is a promising novel technology in interventional electrophysiology.

Do Prostate HDR Brachytherapy Catheters Shift between Planning and Treatment Delivery?

Do Prostate HDR Brachytherapy Catheters Shift between Planning and Treatment Delivery?

Justification for inter-fraction correction of catheter movement in fractionated high dose-rate brachytherapy treatment of prostate cancer

Background and purpose Fractionated high dose-rate (HDR) brachytherapy in the treatment of prostate cancer relies on reproducible catheter positions for each fraction to ensure adequate tumour coverage while minimising dose to normal tissues. Peri-prostatic oedema may cause caudal displacement of the catheters relative to the prostate gland between fractions. This can be corrected for by changing source dwell positions or by physical re-advancement of catheters before treatment. Materials and methods Data for 20 consecutive monotherapy patients receiving three HDR fractions of 10.5 Gy per fraction over 2 days were analysed retrospectively. Pre-treatment CT scans were used to assess the effect of catheter movement between fractions on implant quality, with and without movement correction. Implant quality was evaluated using dosimetric parameters. Results Compared to the first fraction (f1) the mean inter-fraction caudal movement relative to the prostate base was 7.9 mm (f2) (range 0–21 mm) and 3.9 mm (f3) (range 0–25.5 mm). PTV D90% was reduced without movement correction by a mean of 27.8% (f2) and 32.3% (f3), compared with 5.3% and 5.1%, respectively, with catheter movement correction. Dose to 2 cc of the rectum increased by a mean of 0.69 (f2) and 0.76 Gy (f3) compared with an increase of 0.03 and 0.04 Gy, respectively, with correction. The urethra V12 also increased by a mean of 0.36 (f2) and 0.39 Gy (f3) compared with 0.06 and 0.16 Gy, respectively, with correction. Conclusions Inter-fraction correction for catheter movement using pre-treatment imaging is critical to maintain the quality of an implant. Without movement correction there is significant risk of tumour under-dosage and normal tissue over-dosage. The findings of this study justify additional imaging between fractions in order to carry out correction.

Characterization of Catheter Dynamics During Percutaneous Transluminal Catheter Procedures

Remote catheter navigation systems are being developed to reduce the occupational risk of the intervening physician. Despite the success of such systems, development has occurred with little fundamental knowledge of the catheter dynamics applied by the interventionalist. This paper characterizes the kinematics of a catheter during manipulation, the minimum applied force/torque during interventional procedures, and the maximum force/torque applied by an operator to overcome vasculature friction. Ten operators manipulated a 6F catheter inside a specialized catheter movement sensor to determine the velocities and accelerations of catheter motion. A mass-spring apparatus was constructed to measure the forces and torques required to overcome introducer sheath and vasculature friction. Results showed the catheter was manipulated at peak velocities and accelerations of (mu +/- sigma): 360 +/-180 mm x s(-1) and 22200 +/-14000 mm x s(- 2), and 19 +/-7 rad x s(- 1) and 900 +/-510 rad x s(- 2), for axial and radial directions of motion, respectively. A minimum force of 0.29 +/- 0.06 N and a torque of 1.15 +/-0.3 mN x m was required to move the catheter through the introducer sheath; while the observed maximum applied torque was 15 mN x m to overcome vasculature friction. The implications of these results for future design optimization of an intuitive remote catheter navigation system are considered.

Toward true 3D visualization of active catheters using compressed sensing

A crucial requirement in MR-guided interventions is the visualization of catheter devices in real time. However, true 3D visualization of the full length of catheters has hitherto been impossible given scan time constraints. Compressed sensing (CS) has recently been proposed as a method to accelerate MR imaging of sparse objects. Images acquired with active interventional devices exhibit a high CNR and are inherently sparse, therefore rendering CS ideally suited for accelerating data acquisition. A framework for true visualization of active catheters in 3D is proposed employing CS to gain high undersampling factors making real-time applications feasible. Constraints are introduced taking into account prior knowledge of catheter geometry and catheter motion over time to improve and accelerate image reconstruction. The potential of the method is demonstrated using computer simulations and phantom experiments and in vivo feasibility is demonstrated in a pig experiment.

Fabrication and characterization of laser-micromachined polypyrrole-based artificial muscle actuated catheters

Minimally invasive surgical tools using catheter based technology plays an important role in biomedical diagnostics and treatments. Much research has focused on producing an actively controllable tip catheter to improve accuracy and efficiency over traditional passive catheters when navigating inside patients. In this work, we describe the design, fabrication and characterization of a novel laser-micromachined polypyrrole (PPy) based active catheter. Two-dimensional controlled bending motion of a four-electrode catheter is demonstrated. Combining such catheter with optical coherence tomography, which can provide subsurface visualization of biological tissue, imaging capability using the active catheter tip is also demonstrated.

37 oral: Hdr Monotherapy for Prostate Cancer: A Simulation Study to Determine the Effect of Catheter Movement on Target Coverage and Normal Tissue Irradiation

37 oral: Hdr Monotherapy for Prostate Cancer: A Simulation Study to Determine the Effect of Catheter Movement on Target Coverage and Normal Tissue Irradiation

Novel catheter guidance technique to the site of origin of the arrhythmia

The purpose of this study was to evaluate the accuracy of our catheter guidance system using Single Equivalent Moving Dipole (SEMD) method to guide the tip of the cardiac ablation catheter to the site of origin of the arrhythmia. 3 different patterns of 8 bipolar electrodes were sutured on the right ventricular myocardium of 3 swine through a standard thoracotomy. Electrode cables passed subcutaneously to a ventral interscapular position were exteriorized, fixed by stay sutures, and the chest closed in layers. The animals' heart rate, pulse oximetry, femoral artery blood pressure, and body temperature were continuously monitored. As the epicardial electrodes connected to a stimulator delivered pacing spikes simulating focal ventricular tachycardia at a rate of 120 bpm, the BioSemi ActiveTwo system at a frequency of 1Khz with a symmetrically patterned array of 64 electrodes placed on the chest measured body surface potentials. A paralytic drug was used to reduce error in cardiac mapping by minimizing muscular activity and allowing for full respirator control of breathing. Both simulation and real catheter's movements were well detected (R=0.95) and the final localization error of a simulation catheter to a pre‐defined target was less than 1 cm in imaginary space, which is equal to 0.4 cm in real space. These data support the validity of SEMD method for localizing the origin of arrhythmia in swine model.

Distal Baclofen Pump Catheter Migration Associated with Far-Lateral Paraspinal Surgical Placement

Objectives. The increased rigidity and spasms implicit to patients being treated with baclofen provide a potential source of drugdeliverysystem-related complications. Placement of the intrathecal catheter from the far-lateral paraspinal approach has been advocated to avoid catheter fracture as previously reported with a midline approach. A thin fascial layer and increased muscle bulk laterally could increase motion of catheters placed in this position. The authors report on a series of patients found to have spinal catheter migration out from the thecal sac following a far-lateral paraspinal surgical approach. Materials and Methods. The medical records of six consecutive patients who required revision of an intrathecal baclofen infusion system secondary to spinal catheter migration were included in this retrospective review. Each patient failed to respond to oral antispasmodic therapy and showed a positive response to a trial of intrathecal baclofen before initial pump implantation. Clinical notes and operative reports were reviewed. Results. All patients had a baclofen pump inserted with the intrathecal catheter placed through the far-lateral portion of the paraspinal musculature entering above the lumbar vertebral pedicle. In all cases, the spinal catheter migrated and was found coiled outside of the thecal sac. In two patients, this occurred on two separate occasions. Mean time to catheter revision following implantation was 7±2months. Conclusions. Spinal catheter migration from the subarachnoid space can occur with intrathecal baclofen infusion systems. Alternative methods for spinal catheter placement warrant further study.

Design and Performance Evaluation of a Remote Catheter Navigation System

A novel remote catheter navigation system has been developed to reduce physical stress and irradiation to the interventionalist during fluoroscopic X-ray guided catheter intervention. The unique teleoperated design of this system allows the interventionalist to apply conventional axial and radial motion, as used in current practice, to an input catheter placed in a radiation-safe location to control a second catheter placed inside the procedure room. A catheter sensor (used to measure motion of the input catheter) and a catheter manipulator (used to manipulate the second catheter) are both presented. Performance evaluation of the system was assessed by first conducting bench-top experiments to quantify accuracy and precision of both sensed and replicated motion, and then conducting two experiments to evaluate the latency from sensed to replicated motion. The first study consisted of replicating motions of prescribed motion trajectories, while the second study utilized eight operators to remotely navigate a catheter through a normal carotid model. The results show the system has the ability to sense and replicate motion to within 1 mm and 1 ( degrees ) in the axial and radial directions, respectively. Remote catheter manipulation was found to be operator dependent and occurred under 300 ms. Future applications of this technology are then presented.

Optimal pH Monitor Placement for Diagnosing GERD

Traditional, 24-hour, catheter-based pH monitoring fails to establish a diagnosis of gastroesophageal reflux disease in 13% to 23% of patients (Gastroenterology 1987; 93:85). This variable sensitivity is mainly due to catheter movement caused by patients swallowing, breathing, and changing body positions. To limit this effect, and to limit transient migration of the pH monitor electrode into the proximal stomach, physicians are advised to position electrodes 6 cm above the upper border of the lower esophageal sphincter (LES). Although a wireless pH monitoring system (JW Gastroenterol …

Infectious Risk of Continuous Peripheral Nerve Blocks

Infectious Risk of Continuous Peripheral Nerve Blocks

Catheter Ablation – New Developments in Robotics

Catheter ablation has become the curative treatment modality for various arrhythmias. Extending the indications for catheter ablation from simple supraventricular tachycardias to complex arrhythmias such as ventricular tachycardia or atrial fibrillation, the investigator faces prolonged procedure times, fluoroscopy exposure and the need for stable and reproducible catheter movement. Recently, remote-controlled robotic catheter ablation has emerged as a novel ablation concept to meet these requirements. This review describes the two available robotic ablation systems and summarizes their clinical applications and current human experience.