المؤلفون: Kenta Tsutsui, Naokata Sumitomo, Shintaro Nakano, Shiro Iwagana, Hitoshi Mori, Yoshifumi Ikeda, Toshihiro Muramatsu, Hidehira Fukaya, Daisuke Kawano, Kazuo Matsumoto, Ritsushi Kato

المصدر: Journal of Cardiovascular Electrophysiology. 32:2069-2076

مصطلحات موضوعية: Catheters, Swine, business.industry, Radiofrequency ablation, medicine.medical_treatment, Drop (liquid), Models, Theoretical, Ablation, law.invention, Lesion, Steam, Catheter, Volume (thermodynamics), law, Physiology (medical), Catheter Ablation, Electric Impedance, medicine, Animals, Cutoff, medicine.symptom, Cardiology and Cardiovascular Medicine, Nuclear medicine, business, Lead (electronics)

الوصف: Background The local impedance (LI) reflects the electrical catheter-tissue coupling and correlates with the local tissue temperature. However, there have been few clinical studies showing the recommended method for LI monitoring catheters. This study aimed to investigate the optimal ablation setting for this catheter in an in vitro experimental model. Methods LI monitoring catheters were used in an excised swine heart experimental model. The tissue contact force (CF) was directly monitored from an external weight scale. Radiofrequency ablation was performed with a combination of various energy power settings (30, 40, and 50W), and various CFs (10, 30, and 50g) for 60 seconds. The correlation between the LI-related indexes, power, and CF with the lesion formation was statistically analyzed. Results A positive correlation between the LI or lesion formation and CF was observed under all powers. Although the LI drop always correlated with the maximum lesion depth, lesion diameter, and lesion volume, the coefficient of the correlation value was lower under a high CF (lesion depth, diameter, and volume; 10g, r=0.8064, r=0.8389, r=0.8477; 30g, r=0.7590, r=0.8063, r=0.8060; 50g r=0.5555, r=0.5701, and r=0.5678, respectively). Steam pops occurred only under a 50W ablation and the LI drop cutoff value for steam pops was 46Ω. Conclusion The same LI drop did not always lead to the same lesion size when the CF differed. Monitoring the LI and not exceeding 46Ω would be useful for a safe ablation. This article is protected by copyright. All rights reserved.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c75ce960b546b1cfb2cf474601f76654Test
https://doi.org/10.1111/jce.15136Test

المؤلفون: Hidehira Fukaya, Naokata Sumitomo, Hitoshi Mori, Toshihiro Muramatsu, Kenta Tsutsui, Daisuke Kawano, Shiro Iwanaga, Ritsushi Kato, Shintaro Nakano, Yoshifumi Ikeda, Kazuo Matsumoto

المصدر: Journal of cardiovascular electrophysiologyREFERENCES. 32(12)

مصطلحات موضوعية: Catheters, Radiofrequency ablation, Swine, medicine.medical_treatment, Heart Ventricles, law.invention, Contact force, Lesion, law, Physiology (medical), medicine, Electric Impedance, Animals, Electrical impedance, business.industry, Drop (liquid), Ablation, Steam, medicine.anatomical_structure, Ventricle, Catheter Ablation, medicine.symptom, Cardiology and Cardiovascular Medicine, business, Ex vivo, Biomedical engineering

الوصف: Background Local impedance (LI) has emerged as a new technology that informs on electrical catheter-tissue coupling during radiofrequency (RF) ablation. Recently, IntellaNav StablePoint, a novel LI-enabled catheter that equips contact force (CF) sensing, has been introduced. Although StablePoint and its predecessor IntellaNav MiFi OI share the common technology that reports LI, distinct mechanics for LI sensing between the 2 products raise a concern that the LI-RF lesion formation relationship may differ. Methods In an ex vivo swine cardiac tissue model, we investigated the initial level and range of a reduction in LI during a 60-second RF ablation and the resultant lesion characteristics at 9 combinations of 3 energy power (30, 40, and 50W) and CF (10, 30, and 50g) steps. Correlations and interactions between CF, LI, wattage, and formed lesions were analyzed. Incidence of achieving LI drop plateau and that of a steam pop were also determined. Results Positive correlations existed between CF and initial LI, CF and absolute/relative LI drop, CF and lesion volume, and LI drop and lesion volume. At the same LI drop, wattage-dependent gain in lesion volume was observed. Steam pops occurred in all CF steps and the prevalence was highest at 50W. LI drop predicted a steam pop with a cutoff value at 89Ω. Conclusion In StablePoint, wattage crucially affects LI drop and lesion volume. Because 30W ablation may by underpowered for intramural lesion formation and 50W often resulted in a steam pop, 40W appears to achieve the balance between the safety and efficacy. This article is protected by copyright. All rights reserved.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5e6933e6feca912fc48621490e46a36cTest
https://pubmed.ncbi.nlm.nih.gov/34559441Test

المؤلفون: Ritsushi Kato, Shiro Iwanaga, Toshihiro Muramatsu, Kazuo Matsumoto, Hitoshi Mori, So Asano, Koji Goto, Midori Yukino, Hisamitsu Mukaida, Yoshifumi Ikeda, Takahiko Nagase

المصدر: Journal of Cardiovascular Electrophysiology. 30:1330-1338

مصطلحات موضوعية: Time Factors, medicine.medical_treatment, Lesion volume, In Vitro Techniques, 030204 cardiovascular system & hematology, Balloon, In vitro model, law.invention, Lesion, 03 medical and health sciences, 0302 clinical medicine, law, Physiology (medical), medicine, Animals, 030212 general & internal medicine, Muscle, Skeletal, business.industry, Lesion depth, Ablation, Laser, Laser Therapy, medicine.symptom, Cardiology and Cardiovascular Medicine, Nuclear medicine, business, Chickens, Energy (signal processing)

الوصف: INTRODUCTION The influence of power (Watt [W]) and total energy (Joule [J]) on lesion size and the optimal overlap ratio remain unclear in laser balloon (LB) ablation for atrial fibrillation. We aimed to evaluate lesion size and visible gaps after LB ablation with various energy settings and different overlap ratios in vitro model. METHODS AND RESULTS Chicken muscles were cauterized using the first-generation LB with single applications of full and a half duration of six energy settings (5.5 W/30 seconds [165 J] to 12 W/20 seconds [240 J]) and varying power (5.5-12 W) at the constant total energy (160 J). Three overlapped ablations with different ratios (25% and 50%) for each energy setting were also performed to evaluate the visible gap degree categorized from 1 (perfect) to 3 (poor). Twenty lesions were evaluated for each energy setting. In single applications of full duration, lesion depth, lesion volume, and maximum lesion diameter increased according to the total energy (all, P

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1f365a488f3504857c383e7336eda443Test
https://doi.org/10.1111/jce.14040Test

المؤلفون: Glenn Meininger, Ritsushi Kato, Aravindan Kolandaivelu, Albert C. Lardo, Saman Nazarian, Hugh Calkins, Ariel Roguin, David A. Bluemke, Robert C. Susil, Ronald D. Berger, Hiroshi Ashikaga, Timm L. Dickfeld, Menekhem M. Zviman, Henry R. Halperin

المصدر: Circulation. 118:223-229

مصطلحات موضوعية: Bundle of His, Cardiac Catheterization, medicine.medical_specialty, Hot Temperature, medicine.medical_treatment, Magnetic Resonance Imaging, Interventional, Article, Catheterization, Dogs, Computer Systems, Physiology (medical), medicine, Animals, Humans, Fluoroscopy, Heart Atria, Cardiac catheterization, medicine.diagnostic_test, Echo-Planar Imaging, business.industry, Cardiac Pacing, Artificial, Magnetic resonance imaging, Real-time magnetic resonance imaging, Electrophysiology, Catheter, medicine.anatomical_structure, Ventricle, Feasibility Studies, Radiology, Cardiology and Cardiovascular Medicine, business, Biomedical engineering

الوصف: Background— Compared with fluoroscopy, the current imaging standard of care for guidance of electrophysiology procedures, magnetic resonance imaging (MRI) provides improved soft-tissue resolution and eliminates radiation exposure. However, because of inherent magnetic forces and electromagnetic interference, the MRI environment poses challenges for electrophysiology procedures. In this study, we sought to test the feasibility of performing electrophysiology studies with real-time MRI guidance. Methods and Results— An MRI-compatible electrophysiology system was developed. Catheters were targeted to the right atrium, His bundle, and right ventricle of 10 mongrel dogs (23 to 32 kg) via a 1.5-T MRI system using rapidly acquired fast gradient-echo images (≈5 frames per second). Catheters were successfully positioned at the right atrial, His bundle, and right ventricular target sites of all animals. Comprehensive electrophysiology studies with recording of intracardiac electrograms and atrial and ventricular pacing were performed. Postprocedural pathological evaluation revealed no evidence of thermal injury to the myocardium. After proof of safety in animal studies, limited real-time MRI-guided catheter mapping studies were performed in 2 patients. Adequate target catheter localization was confirmed via recording of intracardiac electrograms in both patients. Conclusions— To the best of our knowledge, this is the first study to report the feasibility of real-time MRI-guided electrophysiology procedures. This technique may eliminate patient and staff radiation exposure and improve real-time soft tissue resolution for procedural guidance.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dfd964da8c3747d01f205916de6989a9Test
https://doi.org/10.1161/circulationaha.107.742452Test

المؤلفون: Ritsushi Kato, Ariel Roguin, Ravi Ranjan, Gordon F. Tomaselli, Ronald D. Berger, Timm Dickfeld, Menekhem M. Zviman, Henry R. Halperin

المصدر: Circulation. Arrhythmia and electrophysiology. 4(3)

مصطلحات موضوعية: Male, medicine.medical_specialty, medicine.medical_treatment, Catheter ablation, Ventricular tachycardia, Article, Intraoperative Period, Dogs, Heart Conduction System, Heart Rate, Physiology (medical), Atrial Fibrillation, medicine, Animals, Heart Atria, Atrial tachycardia, medicine.diagnostic_test, business.industry, Body Surface Potential Mapping, Atrial fibrillation, Magnetic resonance imaging, Recovery of Function, medicine.disease, Ablation, Magnetic Resonance Imaging, Surgery, Disease Models, Animal, Treatment Outcome, Ventricular fibrillation, Catheter Ablation, Female, Radiology, medicine.symptom, Electrical conduction system of the heart, Cardiology and Cardiovascular Medicine, business, Follow-Up Studies

الوصف: Background— Ablation has become an important tool in treating atrial fibrillation and ventricular tachycardia, yet the recurrence rates remain high. It is well established that ablation lines can be discontinuous and that conduction through the gaps in ablation lines can be affected by tissue heating. In this study, we looked at the effect of tissue conductivity and propagation of electric wave fronts across ablation lines with gaps, using both simulations and an animal model. Methods and Results— For the simulations, we implemented a 2-dimensional bidomain model of the cardiac syncytium, simulating ablation lines with gaps of varying lengths, conductivity, and orientation. For the animal model, transmural ablation lines with a gap were created in 7 mongrel dogs. The gap length was progressively decreased until there was conduction block. The ablation line with a gap was then imaged using MRI and was correlated with histology. With normal conductivity in the gap and the ablation line oriented parallel to the fiber direction, the simulation predicted that the maximum gap length that exhibited conduction block was 1.4 mm. As the conductivity was decreased, the maximum gap length with conduction block increased substantially, that is, with a conductivity of 67% of normal, the maximum gap length with conduction block increased to 4 mm. In the canine studies, the maximum gap length that displayed conduction block acutely as measured by gross pathology correlated well ( R 2 of 0.81) with that measured by MRI. Conclusions— Conduction block can occur across discontinuous ablation lines. Moreover, with recovery of conductivity over time, ablation lines with large gaps exhibiting acute conduction block may recover propagation in the gap over time, allowing recurrences of arrhythmias. The ability to see gaps acutely using MRI will allow for targeting these sites for ablation.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5733f6e238daded667cef9070b202d54Test
https://pubmed.ncbi.nlm.nih.gov/21673023Test

المؤلفون: Hiroshi Ashikaga, Ronald D. Berger, Hugh Calkins, Henry R. Halperin, Albert C. Lardo, Timm Dickfeld, Jun Dong, Ritsushi Kato, Menekem Zviman, Saman Nazarian

المصدر: Heart rhythm. 4(2)

مصطلحات موضوعية: medicine.medical_specialty, Radiofrequency ablation, medicine.medical_treatment, Catheter ablation, Article, law.invention, Lesion, Dogs, law, Physiology (medical), medicine, Animals, Analysis of Variance, medicine.diagnostic_test, business.industry, Magnetic resonance imaging, Ablation, Magnetic Resonance Imaging, Acute Disease, Catheter Ablation, Linear Models, Gross anatomy, Histopathology, Radio frequency, Radiology, medicine.symptom, Cardiology and Cardiovascular Medicine, business, Pericardium

الوصف: Background Magnetic resonance imaging (MRI) has the potential to visualize radiofrequency (RF) ablations, which have become the preferred strategy for treatment of many arrhythmias. However, MRI patterns after RF ablation have not been well investigated. Objective The purpose of this study was to define the characteristic appearance and the effect of time and energy on noncontrast-enhanced MRI of RF ablation. Methods Using a power-controlled, cooled-tip ablation system, RF ablation lesions (5–50 W for 45 seconds) were created on the right ventricular epicardium in 10 mongrel dogs. T1- and T2-weighted MR images were obtained during 12-hour follow-up and compared with gross anatomy and histopathology. Results Lesions were successfully visualized with T2- and T1-weighted images 30 minutes to 12 hours after RF ablation. T2 images were more consistent and displayed a characteristic elliptical, high-signal core (contrast-to-noise-ratio [CNR] = 18.9 ± 8.4) with a surrounding 0.5-mm low-intensity rim that on histopathology corresponded to the central tissue necrosis and the transition zone, respectively. T1 images showed a less remarked increase in signal intensity (CNR = 9.6 ± 7.4) without a surrounding rim. Lesion size and appearance were well defined and unchanged during the 12-hour follow-up (analysis of variance). CNR was independent of applied RF energy and allowed accurate assessment of RF ablation at all time points (r = 0.87 and r=0.83 for T2 and T1 images, respectively). Transmural lesions, interlesional gaps, and intralesional pathology could be reliably predicted in >90%. Conclusion Noncontrast-enhanced MRI allows accurate assessment of RF ablation and its intralesional pathology during 12-hour follow-up. This finding confirms a possible role of MRI in guiding and evaluating RF application during electrophysiologic ablation procedures.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f987953ca80578ab9bb773d626a3fd9cTest
https://pubmed.ncbi.nlm.nih.gov/17275760Test

المؤلفون: Ritsushi Kato, Glenn Meininger, Ron Berger, Timm Dickfeld, Lars Lickfett, Stephen B. Solomon, Hugh Calkins, Muz Zviman, Henry R. Halperin

المصدر: Circulation. 108(19)

مصطلحات موضوعية: Male, medicine.medical_specialty, Cardiac Catheterization, Swine, medicine.medical_treatment, Heart Ventricles, Ablation of atrial fibrillation, Catheter ablation, Imaging phantom, Stereotaxic Techniques, Imaging, Three-Dimensional, Computer Systems, Physiology (medical), medicine, Fluoroscopy, Animals, Heart Atria, medicine.diagnostic_test, business.industry, Phantoms, Imaging, Reproducibility of Results, Arrhythmias, Cardiac, Ablation, medicine.disease, Magnetic Resonance Imaging, Surgery, Computer-Assisted, Heart catheterization, Catheter Ablation, Radiology, Cardiology and Cardiovascular Medicine, business, Fiducial marker, Electromagnetic Phenomena, Atrial flutter

الوصف: Background— Targets for radiofrequency (RF) ablation of atrial fibrillation, atrial flutter, and nonidiopathic ventricular tachycardia are increasingly being selected on the basis of anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures and is associated with radiation risk, other approaches to mapping may be beneficial. Methods and Results— An electromagnetic catheter positioning system was superimposed on 3D MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MR images in real time. In vitro accuracy and precision during catheter navigation were assessed in a phantom model and were 1.11±0.06 and 0.30±0.07 mm (mean±SEM), respectively. Left and right heart catheterization was performed in 7 swine without the use of fluoroscopy, yielding an in vivo accuracy and precision of 2.74±0.52 and 1.97±0.44 mm, respectively. To assess the reproducibility of RF ablation, RF lesions were created repeatedly at the identical anatomic site in the right atrium (n=8 swine). Average distance of the repeated right atrial ablations was 3.92±0.5 mm. Straight 3-point lines were created in the right and left ventricles to determine the ability to facilitate complex ablation procedures (n=6 swine). The ventricular lesions deviated 1.70±0.24 mm from a straight line, and the point distance differed by 2.25±0.63 mm from the pathological specimen. Conclusions— Real-time display of the catheter position on 3D MRI allows accurate and precise RF ablation guided by the true anatomy. This may facilitate anatomically based ablation procedures in, for instance, atrial fibrillation or nonidiopathic ventricular tachycardia and decrease radiation times.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::acf33506c925520274ba6c0f41b49e60Test
https://pubmed.ncbi.nlm.nih.gov/14568905Test

المؤلفون: Timm Dickfeld, Shenghan Lai, Ritsushi Kato, Hugh Calkins, Menekhem M. Zviman, Ronald D. Berger, Henry R. Halperin, Ariel Roguin, Albert C. Lardo, Glenn Meininger, David A. Blumke

المصدر: Journal of the American College of Cardiology. (2):370-378

مصطلحات موضوعية: medicine.medical_specialty, Radiofrequency ablation, medicine.medical_treatment, Gadolinium, chemistry.chemical_element, Catheter ablation, 030204 cardiovascular system & hematology, Article, 030218 nuclear medicine & medical imaging, law.invention, Lesion, 03 medical and health sciences, Necrosis, 0302 clinical medicine, Dogs, law, medicine, Animals, Myocardial infarction, medicine.diagnostic_test, business.industry, Myocardium, Magnetic resonance imaging, medicine.disease, Image Enhancement, Magnetic Resonance Imaging, medicine.anatomical_structure, chemistry, Ventricle, Catheter Ablation, cardiovascular system, Histopathology, Radiology, medicine.symptom, Cardiology and Cardiovascular Medicine, business, Electrophysiologic Techniques, Cardiac, Pericardium

الوصف: ObjectivesThis study was designed to evaluate the characteristics of gadolinium-enhanced imaging of radiofrequency ablations.BackgroundGadolinium-enhanced magnetic resonance imaging (MRI) has been used successfully to evaluate tissue necrosis after myocardial infarction. In electrophysiology, radiofrequency energy is used to create a targeted myocardial necrosis for the treatment of various arrhythmias.MethodsUsing a power-controlled, cooled-tip 7-F catheter system, radiofrequency lesions (10 to 40 W for 30 s) were created on the epicardium of the right ventricle in eight mongrel dogs. After injection of 0.225 mmol/kg gadolinium, T1-weighted fast gradient echo images were obtained during a follow-up of 10 h using an intrathoracic high-resolution coil. Radiofrequency ablations were analyzed on the MR images and compared with gross anatomy and histopathology.ResultsFour distinct phases of signal enhancement were observed. After gadolinium injection, radiofrequency lesions were delineated clearly as contrast-free areas of low signal intensity (contrast-to-noise ratio [CNR] = −21.1 ± 19.8). Signal enhancement in the lesion periphery started 4.0 ± 1.8 min after injection and progressively extended toward the lesion center at a rate of 0.02 mm/min. Full delayed enhancement was observed after 98 ± 21 min (CNR = +17.8 ± 9.0). During the follow-up period, CNR started to decrease, but the lesions were detectable for as long as 10 h of follow-up. During the first three phases of enhancement, MRI correlated well with the pathological findings (r = 0.88, r = 0.88, and r = 0.86 [p < 0.001], respectively).ConclusionsRadiofrequency ablation can be evaluated accurately by using gadolinium-enhanced MRI, which may allow the noninvasive assessment of procedural success. The dissimilar wash-in and wash-out kinetics compared with myocardial infarction suggest a different pathophysiological process with complete loss of microvasculature.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7e13ef023b06e2948aca1e2cd4360348Test