FROM CONCEPT, TO DESIGN, EVALUATION AND FIRST IN VIVO DEMONSTRATION OF A TELE-OPERATED CATHETER NAVIGATION SYSTEM

Percutaneous transluminal catheter (PTC) intervention is a medical technique used to assess and treat vascular and cardiac diseases, including electrophysiological conditions. A Interventional specialists use the vasculature as a passageway to guide the catheter to the site of interest, using fluoroscopic x-ray imaging for image-guidance. Common PTC procedures include: vascular angiography, inflating balloons and stents, depositing coils, and the treatment of cardiac arrhythmia via catheter ablation. Catheter ablation has gained prevalence over the last two decades, as the treatment success rate for atrial fibrillation reaches 100%. The close proximity between the interventionalist and the radiation source combined with the increased number of procedures performed annually has lead to increased lifetime exposure; escalating the interventionalist probability of developing cancer, cataracts or passing genetic defects to offspring. Furthermore, the lead garments that protect the interventionalist can lead to musculoskeletal injury. Both these factors have lead to increased occupational risk. Catheter navigation systems are commercially available to reduce these risks. Lack of intuitive design is a common failing among these systems. iii This thesis presents the design and validation of a remote catheter navigation system (RCNS) that utilizes dexterous skills of the interventionalist during remote navigation, by keeping the catheter in their hands of the interventionalist during remote navigation. For remote catheter manipulation, the interventionalist pushes, pulls, and twists an input catheter, which is placed inside an electromechanical sensor (CS). Position changes of the input catheter are transferred to a second electromechanical (CM) that replicates the sensed motion with a second, remote catheter. Design of this system begins with understanding the dynamic forces applied to the catheter during intravascular navigation. These dynamics were quantified and then used as operating parameters in the mechanical design of the CM. In a laboratory setting, motion sensed and replicated by the RCNS was found to be 1 mm in the axial direction, 1° in the radial direction, with a latency of 180 ms. In a multi-operator, comparative study using a specially constructed multi-path vessel phantom, comparable navigation efficacy was demonstrated between the RCNS and conventional catheter manipulation, with the RCNS requiring only 9s longer to complete the same tasks. Finally, remote navigation was performed in vivo to fully demonstrate the application of this system towards the diagnosis and treatment of cardiac arrhythmia

FROM CONCEPT, TO DESIGN, EVALUATION AND FIRST IN VIVO DEMONSTRATION OF A TELE-OPERATED CATHETER NAVIGATION SYSTEM

Percutaneous transluminal catheter (PTC) intervention is a medical technique used to assess and treat vascular and cardiac diseases, including electrophysiological conditions. Interventional specialists use the vasculature as a passageway to guide the catheter to the site of interest, using fluoroscopic x-ray imaging for image-guidance. Common PTC procedures include: vascular angiography, inflating balloons and stents, depositing coils, and the treatment of cardiac arrhythmia via catheter ablation. Catheter ablation has gained prevalence over the last two decades, as the treatment success rate for atrial fibrillation reaches 100%. The close proximity between the interventionalist and the radiation source combined with the increased number of procedures performed annually has lead to increased lifetime exposure; escalating the interventionalist probability of developing cancer, cataracts or passing genetic defects to offspring. Furthermore, the lead garments that protect the interventionalist can lead to musculoskeletal injury. Both these factors have lead to increased occupational risk. Catheter navigation systems are commercially available to reduce these risks. Lack of intuitive design is a common failing among these systems. iii This thesis presents the design and validation of a remote catheter navigation system (RCNS) that utilizes dexterous skills of the interventionalist during remote navigation, by keeping the catheter in their hands of the interventionalist during remote navigation. For remote catheter manipulation, the interventionalist pushes, pulls, and twists an input catheter, which is placed inside an electromechanical sensor (CS). Position changes of the input catheter are transferred to a second electromechanical (CM) that replicates the sensed motion with a second, remote catheter. Design of this system begins with understanding the dynamic forces applied to the catheter during intravascular navigation. These dynamics were quantified and then used as operating parameters in the mechanical design of the CM. In a laboratory setting, motion sensed and replicated by the RCNS was found to be 1 mm in the axial direction, 1° in the radial direction, with a latency of 180 ms. In a multi-operator, comparative study using a specially constructed multi-path vessel phantom, comparable navigation efficacy was demonstrated between the RCNS and conventional catheter manipulation, with the RCNS requiring only 9s longer to complete the same tasks. Finally, remote navigation was performed in vivo to fully demonstrate the application of this system towards the diagnosis and treatment of cardiac arrhythmia

A magnetic-resonance-imaging-compatible remote catheter navigation system.

A remote catheter navigation system compatible with magnetic resonance imaging (MRI) has been developed to facilitate MRI-guided catheterization procedures. The interventionalist\u27s conventional motions (axial motion and rotation) on an input catheter - acting as the master - are measured by a pair of optical encoders, and a custom embedded system relays the motions to a pair of ultrasonic motors. The ultrasonic motors drive the patient catheter (slave) within the MRI scanner, replicating the motion of the input catheter. The performance of the remote catheter navigation system was evaluated in terms of accuracy and delay of motion replication outside and within the bore of the magnet. While inside the scanner bore, motion accuracy was characterized during the acquisition of frequently used imaging sequences, including real-time gradient echo. The effect of the catheter navigation system on image signal-to-noise ratio (SNR) was also evaluated. The results show that the master-slave system has a maximum time delay of 41 ± 21 ms in replicating motion; an absolute value error of 2 ± 2° was measured for radial catheter motion replication over 360° and 1.0 ± 0.8 mm in axial catheter motion replication over 100 mm of travel. The worst-case SNR drop was observed to be 2.5%

Assessment of percutaneous transluminal coronary angioplasty by quantitative coronary angiography: diameter versus densitometric area measurements

Cineangiograms of 138 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) were analyzed with a computer-based coronary angiography analysis system. The results before and after dilatation are presented. In a first study group (120 patients), the severity of the obstructive lesions derived from the automatically detected contours was evaluated in absolute terms and in percent-diameter reduction. In a second group of patients, 18 coronary lesions were selected for their extreme severity and symmetric aspect before angioplasty as assessed from multiple views. In the second group, the densitometric percent-area stenosis was used to assess the changes in cross-sectional area after PTCA and was compared with the circular percent-area stenosis computed from the diameter measurements. Before PTCA, a good agreement exists between the densitometric percent-area stenosis and the circular percent-area stenosis. After PTCA, important discrepancies between these 2 types of measurements are observed. It is suggested that these discrepancies in results after PTCA can be accounted for by asymmetric morphologic changes in luminal cross section, which cannot be assessed accurately from diameter measurements in a single-plane view

Intravascular Ultrasound

Intravascular ultrasound (IVUS) is a cardiovascular imaging technology using a specially designed catheter with a miniaturized ultrasound probe for the assessment of vascular anatomy with detailed visualization of arterial layers. Over the past two decades, this technology has developed into an indispensable tool for research and clinical practice in cardiovascular medicine, offering the opportunity to gather diagnostic information about the process of atherosclerosis in vivo, and to directly observe the effects of various interventions on the plaque and arterial wall. This book aims to give a comprehensive overview of this rapidly evolving technique from basic principles and instrumentation to research and clinical applications with future perspectives

Pulmonary angioplasty: A step further in the continuously changing landscape of chronic thromboembolic pulmonary hypertension management.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially fatal and frequently undiagnosed form of pulmonary hypertension (PH), classified within group 4 by the World Health Organization (WHO). It is a type of precapillary PH, which uncommonly develops as a peculiar sequel of acute pulmonary embolism due to the partial resolution of the mechanically obstructing thrombus with a coexisting inflammatory response from pulmonary vessels. CTEPH is one of the potentially treatable forms of PH whose current standard of care is surgical pulmonary endarterectomy. Medical therapy with few drugs in non-operable disease is approved and has shown improvement in patients' hemodynamic condition and functional ability. Recently, balloon pulmonary angioplasty (BPA) has shown promising results as a treatment option for technically inoperable patients, those with unacceptable risk-to-benefit ratio and in a case of residual PH after endarterectomy. Lack of meticulous CTEPH screening programs in post-pulmonary embolism patients leading to underdiagnosis of this condition, complex operability assessment, and diversity in BPA techniques among different institutions are still the issues that need to be addressed. In this paper, we review the recent achievements in the management of non-operable CTEPH, their outcome and safety, based on available data

Biodegradable Paclitaxel-loaded Nanoparticles and Stent Coatings as Local Delivery Systems for the Prevention of Restenosis

Despite improved technologies restenosis remains the main problem of catheter-based interventions after a percutaneous transluminal angioplasty in artery disease. Local and sustained application of antiproliferative agents is a promising approach to solve the problem of intimal hyperplasia. In recent years, two different concepts for local drug delivery have attained increased importance: On the one hand, colloidal drug carriers, which can be infused directly into the vessel wall during the angioplasty procedure using special delivery catheters and on the other hand, the development of drug eluting stents. Biocompatible, biodegradable polymers are one of the most important instruments used to control the release of pharmacological active substances. A new type of branched, biodegradable polyesters, poly(vinyl alcohol)-graft-poly(lactide-co-glycolide) (PVA-g-PLGA), possesses very interesting features for the local and sustained release of paclitaxel. Therefore, the objective of this work was to investigate these polymers with regard to the preparation of paclitaxel loaded nanoparticles and stent coatings, and to evaluate their applicability as drug carriers to prevent intimal hyperplasia