1
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Pittman LA, Whittaker P, Milne ML, Chung CS. Collagenase treatment reduces the anisotropy of ultrasonic backscatter in rat myocardium by reducing collagen crosslinks. Physiol Rep 2023; 11:e15849. [PMID: 37960992 PMCID: PMC10643982 DOI: 10.14814/phy2.15849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 11/15/2023] Open
Abstract
Dysregulation of collagen deposition, degradation, and crosslinking in the heart occur in response to increased physiological stress. Collagen content has been associated with ultrasonic backscatter (brightness), and we have shown that the anisotropy of backscatter can be used to measure myofiber alignment, that is, variation in the brightness of a left ventricular short-axis ultrasound. This study investigated collagen's role in anisotropy of ultrasonic backscatter; female Sprague-Dawley rat hearts were treated with a collagenase-containing solution, for either 10 or 30 min, or control solution for 30 min. Serial ultrasound images were acquired at 2.5-min intervals throughout collagenase treatment. Ultrasonic backscatter was assessed from anterior and posterior walls, where collagen fibrils are predominately aligned perpendicular to the angle of insonification, and the lateral and septal walls, where collagen is predominately aligned parallel to the angle of insonification. Collagenase digestion reduced backscatter anisotropy within the myocardium. Collagen remains present in the myocardium throughout collagenase treatment, but crosslinking is altered within 10 min. These data suggest that crosslinking of collagen modulates the anisotropy of ultrasonic backscatter. An Anisotropy Index, derived from differences in backscatter from parallel and perpendicularly aligned fibers, may provide a noninvasive index to monitor the progression and state of myocardial fibrosis.
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Affiliation(s)
| | | | - Michelle L. Milne
- Department of PhysicsSt Mary's College of MarylandSt Mary's CityMarylandUSA
| | - Charles S. Chung
- Department of PhysiologyWayne State UniversityDetroitMichiganUSA
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2
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Zhao X, Ziv O, Mohammadpour R, Crosby B, Hoyt WJ, Jenkins MW, Snyder C, Hendon C, Laurita KR, Rollins AM. Polarization-sensitive optical coherence tomography monitoring of percutaneous radiofrequency ablation in left atrium of living swine. Sci Rep 2021; 11:24330. [PMID: 34934120 PMCID: PMC8692484 DOI: 10.1038/s41598-021-03724-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 12/06/2021] [Indexed: 11/12/2022] Open
Abstract
Radiofrequency ablation (RFA) is commonly used to treat atrial fibrillation (AF). However, the outcome is often compromised due to the lack of direct real-time feedback to assess lesion transmurality. In this work, we evaluated the ability of polarization-sensitive optical coherence tomography (PSOCT) to measure cardiac wall thickness and assess RF lesion transmurality during left atrium (LA) RFA procedures. Quantitative transmural lesion criteria using PSOCT images were determined ex vivo using an integrated PSOCT-RFA catheter and fresh swine hearts. LA wall thickness of living swine was measured with PSOCT and validated with a micrometer after harvesting the heart. A total of 38 point lesions were created in the LA of 5 living swine with the integrated PSOCT-RFA catheter using standard clinical RFA procedures. For all lesions with analyzable PSOCT images, lesion transmurality was assessed with a sensitivity of 89% (17 of 19 tested positive) and a specificity of 100% (5 of 5 tested negative) using the quantitative transmural criteria. This is the first report of using PSOCT to assess LA RFA lesion transmurality in vivo. The results indicate that PSOCT may potentially provide direct real-time feedback for LA wall thickness and lesion transmurality.
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Affiliation(s)
- Xiaowei Zhao
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Ohad Ziv
- School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, USA
| | | | - Benjamin Crosby
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Walter J Hoyt
- Department of Pediatrics, Ochsner Health, New Orleans, LA, USA
| | - Michael W Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, USA
| | - Christopher Snyder
- School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- The Congenital Heart Collaborative, Rainbow Babies and Children's Hospital, Cleveland, OH, USA
| | - Christine Hendon
- Department of Electrical Engineering, Columbia University, New York, NY, USA
| | - Kenneth R Laurita
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, USA
| | - Andrew M Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.
- School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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3
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Romero J, Patel K, Briceno D, Alviz I, Tarantino N, Della Rocca DG, Natale V, Zhang XD, Di Biase L. Fluoroless Atrial Fibrillation Catheter Ablation: Technique and Clinical Outcomes. Card Electrophysiol Clin 2020; 12:233-245. [PMID: 32451107 DOI: 10.1016/j.ccep.2020.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluoroscopy continues to be considered an indispensable part of atrial fibrillation (AF) ablation worldwide. Deleterious effects of radiation exposure to patients, physicians, and catheter laboratory personnel are gaining increased consideration. Safety and efficacy of a fluoroless approach for AF ablation is comparable with outcomes achieved with fluoroscopy use. This article focuses on AF ablation with zero fluoroscopy use as well as current evidence on efficacy and safety of this technique. In contrast, minimal fluoroscopy is an alternative. Relying on intracardiac echocardiography for transseptal access and electroanatomic mapping for catheter manipulation can help implement this approach on a wider scale.
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Affiliation(s)
- Jorge Romero
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | - Kavisha Patel
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | - David Briceno
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | - Isabella Alviz
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | - Nicola Tarantino
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | | | - Veronica Natale
- Texas Cardiac Arrhythmia Institute, St. David's Medical Center, Austin, TX, USA
| | - Xiao-Dong Zhang
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
| | - Luigi Di Biase
- Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA.
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4
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Zhao X, Kilinc O, Blumenthal CJ, Dosluoglu D, Jenkins MW, Snyder CS, Arruda M, Rollins AM. Intracardiac radiofrequency ablation in living swine guided by polarization-sensitive optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-10. [PMID: 32385975 PMCID: PMC7210786 DOI: 10.1117/1.jbo.25.5.056001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
SIGNIFICANCE Pulmonary vein isolation with catheter-based radiofrequency ablation (RFA) is carried out frequently to treat atrial fibrillation. However, RFA lesion creation is only guided by indirect information (e.g., temperature, impedance, and contact force), which may result in poor lesion quality (e.g., nontransmural) and can lead to reoccurrence or complications. AIM The feasibility of guiding intracardiac RFA with an integrated polarization-sensitive optical coherence tomography (PSOCT)-RFA catheter in the right atria (RA) of living swine is demonstrated. APPROACH In total, 12 sparse lesions were created in the RA of three living swine using an integrated PSOCT-RFA catheter with standard ablation protocol. PSOCT images were displayed in real time to guide catheter-tissue apposition. After experiments, post-processed PSOCT images were analyzed to assess lesion quality and were compared with triphenyltetrazolium chloride (TTC) lesion quality analysis. RESULTS Five successful lesions identified with PSOCT images were all confirmed by TTC analysis. In two ablations, PSOCT imaging detected gas bubble formation, indicating overtreatment. Unsuccessful lesions observed with PSOCT imaging were confirmed by TTC analysis. CONCLUSIONS The results demonstrate that the PSOCT-RFA catheter provides real-time feedback to guide catheter-tissue apposition, monitor lesion quality, and possibly help avoid complications due to overtreatment, which may enable more effective and safer RFA treatment.
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Affiliation(s)
- Xiaowei Zhao
- Case Western Reserve University, Department of Biomedical Engineering, Cleveland, United States
| | - Orhan Kilinc
- Rainbow Babies and Children’s Hospital, The Congenital Heart Collaborative, Cleveland, United States
| | - Colin J. Blumenthal
- Case Western Reserve University, School of Medicine, Cleveland, United States
| | - Deniz Dosluoglu
- Case Western Reserve University, Department of Electric Engineering and Computer Science, Cleveland, United States
| | - Michael W. Jenkins
- Case Western Reserve University, Department of Biomedical Engineering, Cleveland, United States
- Case Western Reserve University, Department of Pediatrics, Cleveland, United States
| | - Christopher S. Snyder
- Rainbow Babies and Children’s Hospital, The Congenital Heart Collaborative, Cleveland, United States
- Case Western Reserve University, School of Medicine, Cleveland, United States
- Case Western Reserve University, Department of Pediatrics, Cleveland, United States
| | - Mauricio Arruda
- Case Western Reserve University, School of Medicine, Cleveland, United States
- University Hospitals Cleveland Medical Center, EP Laboratories and the Atrial Fibrillation Center at the Harrington Heart and Vascular Institute, Cleveland, United States
| | - Andrew M. Rollins
- Case Western Reserve University, Department of Biomedical Engineering, Cleveland, United States
- Case Western Reserve University, School of Medicine, Cleveland, United States
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5
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Marshall L, Tarakanova A, Szarek P, Pierce DM. Cartilage and collagen mechanics under large-strain shear within in vivo and at supraphysiogical temperatures. J Mech Behav Biomed Mater 2020; 103:103595. [PMID: 32090923 DOI: 10.1016/j.jmbbm.2019.103595] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/13/2019] [Accepted: 12/10/2019] [Indexed: 11/28/2022]
Abstract
Human joints, particularly those of extremities, experience a significant range of temperatures in vivo. Joint temperature influences the mechanics of both joint and cartilage, and the mechanics of cartilage can affect the temperature of both joint and cartilage. Thermal treatments and tissue repairs, such as thermal chondroplasty, and ex vivo tissue engineering may also expose cartilage to supraphysiological temperatures. Furthermore, although cartilage undergoes principally compressive loads in vivo, shear strain plays a significant role at larger compressive strains. Thus, we aimed to determine whether and how the bulk mechanical responses of cartilage undergoing large-strain shear change (1) within the range of temperatures relevant in vivo, and (2) both during and after supraphysiological thermal treatments. We completed large-strain shear tests (10 and 15%) at four thermal conditions: 24∘C and 40∘C to span the in vivo range, and 70∘C and 24∘C repeated after 70∘C to explore mechanics during and after potential treatments. We calculated the bulk mechanical responses (strain-energy dissipation densities, peak-to-peak shear stresses, and peak-effective shear moduli) as of function of temperature and used statistical methods to probe significant differences. To probe the mechanisms underlying differences we assessed specimens, principally the type II collagen, with imaging (second harmonic generation and transmission electron microscopies, and histology) and assessed the temperature-dependent mechanics of type II collagen molecules within cartilage using steered molecular dynamics simulations. Our results suggest that the bulk mechanical responses of cartilage depend significantly on temperature both within the in vivo range and at supraphysiological temperatures, showing significant reductions in all mechanical measures with increasing temperature. Using imaging and simulations we determined that one underlying mechanism explaining our results may be changes in the molecular deformation profiles of collagen molecules versus temperature, likely compounded at larger length scales. These new insights into the mechanics of cartilage and collagen may suggest new treatment targets for damaged or osteoarthritic cartilage.
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Affiliation(s)
- Lauren Marshall
- Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, CT, 06269, USA
| | - Anna Tarakanova
- Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, CT, 06269, USA; Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269, USA
| | - Phoebe Szarek
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269, USA
| | - David M Pierce
- Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, CT, 06269, USA; Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269, USA.
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6
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Zhao L, Rasko A, Drescher C, Maleki S, Cejnar M, McEwan A. Preliminary Validation of Electroporation-Electrolysis (E2) for Cardiac Ablation Using a Parameterisable In-Vivo Model. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2019:289-293. [PMID: 31945898 DOI: 10.1109/embc.2019.8857828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Atrial fibrillation is the most common arrhythmia, increasing the risk of stroke, heart failure and death, and a growing epidemic. Electroporation ablation is emerging in cardiac ablation for atrial fibrillation as a fast, tissue-specific and non-thermal alternative to existing technologies tied by their thermal action to shortcomings in efficacy, speed and risk. Studies so far have aimed to translate the success of irreversible electroporation from tumour treatment, with its kilovolt pulses, to cardiac ablation. However, these high voltages may be less appealing for cardiac ablation from clinical, technical and regulatory standpoints. A novel ablation technique combining electroporation and electrolysis in a single pulse E2 uses lower voltages. A custom E2 ablation system was developed and tested on an in vivo tissue model. Histopathological analysis showed lesions of clinically relevant depth, achieved without any acute complications or severe muscle contractions. Lesions were mapped onto a numerical model developed to refine further prototyping. This study provides preliminary prototype validation and the methodological foundation for dose optimisation towards endocardial application.
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7
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Barkagan M, Leshem E, Shapira-Daniels A, Sroubek J, Buxton AE, Saffitz JE, Anter E. Histopathological Characterization of Radiofrequency Ablation in Ventricular Scar Tissue. JACC Clin Electrophysiol 2019; 5:920-931. [PMID: 31439293 DOI: 10.1016/j.jacep.2019.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/09/2019] [Accepted: 05/13/2019] [Indexed: 10/26/2022]
Abstract
OBJECTIVES This study sought to characterize the histopathological features of radiofrequency ablation (RFA) in heterogeneous ventricular scar in comparison to those in healthy myocardium. BACKGROUND The histopathological features of RFA have been studied largely in normal myocardium. However, its effect on clinically relevant heterogeneous scar is not well understood. METHODS Five swine with chronic infarction underwent RFA using 35-W, 45-s, 10-20 g (Biosense Webster, Irwindale, California) in heterogenous scar tissue (voltage ≤1.5 mV) and healthy myocardium (≥3.0 mV). The location of each application was marked using the electroanatomical mapping system. Histological sections at intervals of 0.5 mm with hematoxylin and eosin and Masson's trichrome stained intervals were created. A pathologist blinded to the myocardium type characterized the extent of RF injury in cellular, extracellular, and vascular structures. RESULTS In healthy myocardium, 23 of 23 lesions (100%) were well demarcated and could be precisely measured (width: 11.3 ± 3.3 mm; depth: 7.3 ± 2.0 mm). In scar tissue, only 3 of 30 lesions (10%) were identified, and none could be measured due to a lack of defined borders. Lesions in healthy myocardium had a distinctive architecture showing a coagulative necrosis core surrounded by an outer rim of contraction band necrosis. Lesions in scar had ill-defined tissue injury without a distinct architecture. In all ablated regions, viable myocytes remained interspersed between necrotic myocytes exhibiting characteristics of both coagulative and contraction band necrosis. Connective tissue was more resistant to thermal injury in comparison to cardiomyocytes. CONCLUSIONS RFA in scarred myocardium results in irregular tissue injury and unpredictable effect on surviving cardiomyocytes. This may be related to biophysical differences between healthy and scarred myocardium.
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Affiliation(s)
- Michael Barkagan
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Eran Leshem
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Ayelet Shapira-Daniels
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Jakub Sroubek
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Alfred E Buxton
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Jeffrey E Saffitz
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Elad Anter
- Division of Cardiovascular Medicine, Department of Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
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8
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Hendon CP, Lye TH, Yao X, Gan Y, Marboe CC. Optical coherence tomography imaging of cardiac substrates. Quant Imaging Med Surg 2019; 9:882-904. [PMID: 31281782 PMCID: PMC6571187 DOI: 10.21037/qims.2019.05.09] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 05/06/2019] [Indexed: 01/02/2023]
Abstract
Cardiovascular disease is the leading cause of morbidity and mortality in the United States. Knowledge of a patient's heart structure will help to plan procedures, potentially identifying arrhythmia substrates, critical structures to avoid, detect transplant rejection, and reduce ambiguity when interpreting electrograms and functional measurements. Similarly, basic research of numerous cardiac diseases would greatly benefit from structural imaging at cellular scale. For both applications imaging on the scale of a myocyte is needed, which is approximately 100 µm × 10 µm. The use of optical coherence tomography (OCT) as a tool for characterizing cardiac tissue structure and function has been growing in the past two decades. We briefly review OCT principles and highlight important considerations when imaging cardiac muscle. In particular, image penetration, tissue birefringence, and light absorption by blood during in vivo imaging are important factors when imaging the heart with OCT. Within the article, we highlight applications of cardiac OCT imaging including imaging heart tissue structure in small animal models, quantification of myofiber organization, monitoring of radiofrequency ablation (RFA) lesion formation, structure-function analysis enabled by functional extensions of OCT and multimodal analysis and characterizing important substrates within the human heart. The review concludes with a summary and future outlook of OCT imaging the heart, which is promising with progress in optical catheter development, functional extensions of OCT, and real time image processing to enable dynamic imaging and real time tracking during therapeutic procedures.
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Affiliation(s)
| | | | | | - Yu Gan
- Columbia University, New York, NY, USA
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9
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Zhao X, Fu X, Blumenthal C, Wang YT, Jenkins MW, Snyder C, Arruda M, Rollins AM. Integrated RFA/PSOCT catheter for real-time guidance of cardiac radio-frequency ablation. BIOMEDICAL OPTICS EXPRESS 2018; 9:6400-6411. [PMID: 31065438 PMCID: PMC6490984 DOI: 10.1364/boe.9.006400] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 05/21/2023]
Abstract
Radiofrequency ablation (RFA) is an important standard therapy for cardiac arrhythmias, but direct monitoring of tissue treatment is currently lacking. We demonstrate an RFA catheter integrated with polarization sensitive optical coherence tomography (PSOCT) for directly monitoring the RFA process in real time. The integrated RFA/OCT catheter was modified from a standard clinical RFA catheter and includes a miniature forward-viewing cone-scanning OCT probe. The PSOCT system was validated with a quarter-wave plate while the RFA function of the integrated catheter was validated by comparing lesion sizes with those made with an unmodified RFA catheter. Additionally, the integrated catheter guided catheter-tissue apposition and monitored RFA lesion formation in cardiac tissue in real time. The results show that catheter-tissue contact can be characterized by observing the features of the blood and tissue in the acquired OCT images and that RFA lesion formation can be confirmed by monitoring the change in phase retardance in the acquired PSOCT images. This system demonstrates the feasibility of an integrated RFA/OCT catheter to deliver RF energy and image the cardiac wall simultaneously and justifies further research into use of this technology to aid RFA therapy for cardiac arrhythmias.
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Affiliation(s)
- Xiaowei Zhao
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- authors contributed equally
| | - Xiaoyong Fu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- authors contributed equally
| | - Colin Blumenthal
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Yves T. Wang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Michael W. Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Christopher Snyder
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
- Rainbow Babies and Children’s Hospital, Division of Pediatric Cardiology, University Hospitals, Cleveland, OH 44106, USA
| | - Mauricio Arruda
- Department of Cardiology, University Hospitals Case Medical Center, Cleveland, OH 44120, USA
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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10
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Gowda ST, Qureshi AM, Turner D, Madan N, Weigand J, Lorber R, Singh HR. Transseptal puncture using surgical electrocautery in children and adults with and without complex congenital heart disease. Catheter Cardiovasc Interv 2017; 90:E46-E54. [PMID: 28766834 DOI: 10.1002/ccd.27202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 06/15/2017] [Indexed: 11/09/2022]
Abstract
BACKGROUND Atrial transseptal puncture (TSP) for cardiac catheterization procedures remain challenging in children and adults with complex congenital heart disease (CHD). OBJECTIVES We sought to evaluate our experience using radiofrequency (RF) current via surgical electrocautery needle for TSP to facilitate diagnostic and interventional procedures. METHODS Retrospective chart review of all patients (pts) who underwent TSP using RF energy (10-25 W) via surgical electrocautery from three centers from January 2011 to January 2017 were evaluated. Echocardiograms were reviewed to define the atrial septum as normal and complex (thin aneurysmal, thick/fibrotic, synthetic patch material, and extra cardiac conduit). RESULTS A total of 54 pts underwent 55 successful TSP. Median age was 12.5 years (1 day-54 years) and weight was 52.7 kg (2-162). Indications for TSP included; EP study and ablation procedures in structurally normal hearts (n = 24) and in complex atrial septum/CHD and structural heart disease pts (n = 30): Electrophysiology study and ablation in 4, diagnostic catheterization in 9, and interventional procedures in 17 pts were performed. Atrial TSP was successful in 54/55 (98%). Atrial perforation with tiny-small pericardial effusion not requiring intervention was noted in 2 pts. TSP was unsuccessful in one critically ill neonate with unobstructed TAPVR and restricted atrial septum who experienced cardiac arrest requiring CPR, ECMO, and emergent surgery. CONCLUSIONS RF current delivery using surgical electrocautery for TSP is a feasible and an effective option in patients with complex CHD for diagnostic, interventional, and electrophysiology procedures.
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Affiliation(s)
- Srinath T Gowda
- Pediatric Cardiology, The Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, Texas.,Pediatric Cardiology, Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan
| | - Athar M Qureshi
- Pediatric Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Daniel Turner
- Pediatric Cardiology, Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan
| | - Nitin Madan
- Pediatric Cardiology, The Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, Texas
| | - Justin Weigand
- Pediatric Cardiology, The Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, Texas
| | - Richard Lorber
- Pediatric Cardiology, The Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, Texas
| | - Harinder R Singh
- Pediatric Cardiology, The Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, Texas.,Pediatric Cardiology, Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan
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11
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Pinto NC, Chavantes MC, Zezell D, Deana A, Benetti C, Marcos RL, Lopes LA, Martins RABL, Aiello VD, Jatene FB, Pomerantzeff PMA. The use of a high-power laser on swine mitral valve chordae tendineae. Lasers Med Sci 2016; 31:1075-81. [PMID: 27184152 DOI: 10.1007/s10103-016-1949-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/25/2016] [Indexed: 11/28/2022]
Abstract
Worldwide, rheumatic fever remains a significant cause of mitral valve insufficiency. It is responsible for approximately 90 % of early childhood valvular surgeries in Brazil. Elongated or flail chordae are frequently responsible and require surgical correction. The purpose of this study was to analyze and compare the histological tissues of the mitral valve chordae and the mechanical resistance generated by the chordae, both with and without the application of a high-power laser. Twenty normal porcine mitral valve chordae were measured and divided randomly into the following two groups: control group (not subjected to a high-power laser) and laser group (subjected to photonic irradiation). Laser surgery was performed under controlled conditions, using following parameters: λ = 980-nm wavelength, power = 3 W, and energy = 60 J. A mechanical test machine was used in combination with a subsequent histological study to measure chordae tensile properties. A histological analysis demonstrated a typical collagen bundle arrangement in the control group; however, under a particular reached temperature range (48), the collagen bundles assumed different arrangements in the laser group. Significant reductions in the chordae tendineae lengths and changes in their resistance in the laser group were observed, as these chordae exhibited less rigid fibers. The chordae tendineae of normal porcine valves subjected to a high-power laser exhibited its length reduction and less stiffness compared to the control group. A histological analysis of the laser treatment specimens demonstrated differences in collagen bundle spatial organization, following slight changes into tissue temperature.
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Affiliation(s)
- Nathali Cordeiro Pinto
- Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil. .,Valvar Surgery Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Av.Dr. Eneas de Carvalho Aguiar, 2nd floor, 05403-900, São Paulo, SP, Brazil.
| | - M Cristina Chavantes
- Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil.,Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil
| | - Denise Zezell
- Nuclear and Energy Research Institute/Center for Lasers and Applications-IPEN/CLA, University of São Paulo, 2242, Professor Lineu Prestes Avenue, 05508-900, São Paulo, SP, Brazil
| | - Alessandro Deana
- Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil
| | - Carolina Benetti
- Nuclear and Energy Research Institute/Center for Lasers and Applications-IPEN/CLA, University of São Paulo, 2242, Professor Lineu Prestes Avenue, 05508-900, São Paulo, SP, Brazil
| | - Rodrigo Labat Marcos
- Post Graduate Program in Biophotonics and Medicine, University Nove de Julho, 235, Vergueiro, 01504-001, São Paulo, SP, Brazil
| | - Luciana Almeida Lopes
- Research and Education Center for Phototherapy in Health Sciences, 831, Sebastião Moraes, 13562-030, São Carlos, SP, Brazil
| | - Rodrigo A B Lopes Martins
- Institute of Biomedical Sciences - ICB, University of São Paulo, 2415, Professor Lineu Prestes Avenue, Cidade Universitária, 05508-900, São Paulo, SP, Brazil
| | - Vera Demarchi Aiello
- Pathology Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, SS floor, 05403-900, São Paulo, SP, Brazil
| | - Fabio Biscegli Jatene
- Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil
| | - Pablo M A Pomerantzeff
- Cardiovascular and Thoracic Surgery Department of The Heart Institute - General Hospital, Medical School, University of São Paulo, 44, Dr. Enéas de Carvalho Aguiar Avenue, 2nd floor, 05403-900, São Paulo, SP, Brazil.,Valvar Surgery Department of Heart Institute - Clinical Hospital, Medical School, University of São Paulo, 44, Av.Dr. Eneas de Carvalho Aguiar, 2nd floor, 05403-900, São Paulo, SP, Brazil
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12
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Eyerly SA, Vejdani-Jahromi M, Dumont DM, Trahey GE, Wolf PD. The Evolution of Tissue Stiffness at Radiofrequency Ablation Sites During Lesion Formation and in the Peri-Ablation Period. J Cardiovasc Electrophysiol 2015; 26:1009-1018. [PMID: 25970142 PMCID: PMC4643432 DOI: 10.1111/jce.12709] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/27/2015] [Accepted: 05/06/2015] [Indexed: 11/29/2022]
Abstract
Introduction Elastography imaging can provide radiofrequency ablation (RFA) lesion assessment due to tissue stiffening at the ablation site. An important aspect of assessment is the spatial and temporal stability of the region of stiffness increase in the peri‐ablation period. The aim of this study was to use 2 ultrasound‐based elastography techniques, shear wave elasticity imaging (SWEI) and acoustic radiation force impulse (ARFI) imaging, to monitor the evolution of tissue stiffness at ablation sites in the 30 minutes following lesion creation. Methods and Results In 6 canine subjects, SWEI measurements and 2‐D ARFI images were acquired at 6 ventricular endocardial RFA sites before, during, and for 30 minutes postablation. An immediate increase in tissue stiffness was detected during RFA, and the area of the postablation region of stiffness increase (RoSI) as well as the relative stiffness at the RoSI center was stable approximately 2 minutes after ablation. Of note is the observation that relative stiffness in the region adjacent to the RoSI increased slightly during the first 15 minutes, consistent with local fluid displacement or edema. The magnitude of this increase, ∼0.5‐fold from baseline, was significantly less than the magnitude of the stiffness increase directly inside the RoSI, which was greater than 3‐fold from baseline. Conclusions Ultrasound‐based SWEI and ARFI imaging detected an immediate increase in tissue stiffness during RFA, and the stability and magnitude of the stiffness change suggest that consistent elasticity‐based lesion assessment is possible 2 minutes after and for at least 30 minutes following ablation.
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Affiliation(s)
- Stephanie A Eyerly
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | | | - Douglas M Dumont
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Gregg E Trahey
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.,Department of Radiology, Duke University, Durham, North Carolina, USA
| | - Patrick D Wolf
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
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13
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Kornreich M, Heymann M, Fraden S, Beck R. Cross polarization compatible dialysis chip. LAB ON A CHIP 2014; 14:3700-3704. [PMID: 25105977 DOI: 10.1039/c4lc00600c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We visualize birefringence in microliter sample volumes using a microfluidic dialysis chip optimized for cross polarization microscopy. The chip is composed of two overlapping polydimethylsiloxane (PDMS) channels separated by a commercial cellulose ester membrane. Buffer exchange in the sample chamber is achieved within minutes by dialyzing under continuous reservoir flow. Using fd virus as a birefringent model system, we monitor the fd virus isotropic to liquid crystal phase transition as a function of ionic strength. We show that the reorientation of the fd virus spans a few tens of seconds, indicative of fast ion exchange across the membrane. Complete phase separation reorganization takes minutes to hours as it involves diffusive virus mass transport within the storage chamber.
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Affiliation(s)
- Micha Kornreich
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, 69978 Tel Aviv, Israel.
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14
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Rasca E, Nyssen-Behets C, Tielemans M, Peremans A, Hendaoui N, Heysselaer D, Romeo U, Nammour S. Gingiva laser welding: preliminary study on an ex vivo porcine model. Photomed Laser Surg 2014; 32:437-43. [PMID: 25014573 DOI: 10.1089/pho.2013.3662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding. MATERIALS AND METHODS Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera. RESULTS In the laser welding groups, the best tensile strength (p<0.05) was yielded by the 9% ICG saline solution (117 mM) at 4.5 W, 10 Hz, and a fluence of 31.3 kJ/cm(2). The apposition strength revealed no statistically significant difference (p<0.05) between the sutured and the laser welded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 μm at the upper surface. CONCLUSIONS The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.
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Affiliation(s)
- Emilia Rasca
- 1 Department of Dental Sciences, Faculty of Medicine, University of Liège , Liège, Belgium
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15
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Biesbroek M, van Doormaal TPC, van der Zwan A, Tulleken CAF, Regli L, Heijnen HFG, Vink A. The acute effect of increased laser energy during the excimer laser-assisted non-occlusive anastomosis procedure on the vessel wall of the recipient artery: a histopathological study. Lasers Surg Med 2011; 43:522-7. [PMID: 21761423 DOI: 10.1002/lsm.21075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND AND OBJECTIVE The excimer laser-assisted non-occlusive anastomosis (ELANA) technique is a way of making an anastomosis of vessels without temporal occlusion that is used for cerebral revascularization. Currently, 10 mJ of laser energy is used during the ELANA procedure. We have recently demonstrated that increasing the laser energy may increase flap retrieval rate. The aim of the present study was to study the acute effect of increased laser energy during the ELANA procedure on the recipient vessel wall. MATERIALS AND METHODS The ELANA technique was performed on the abdominal aortas of rabbits under anesthesia using three categories of laser energy (two laser episodes of 10, 13, and 15 mJ, respectively). The rabbits were subsequently sacrificed and the anastomoses were removed. A non-lased rabbit aorta was used as control. Recipient arteries were studied using histopathology and transmission electron microscopy. RESULTS In all three categories of laser energy and in the control group, the tunica media and adventitia adjacent to the anastomosis were intact, apart from damage caused by sutures. In the control group, the endothelium was fully intact. In the 10 and 13 mJ subgroups, the endothelium was mostly intact [92% (range 85-98) and 87% (range 80-90) for 10 and 13 mJ, respectively]. In the 15 mJ subgroup, most of the endothelium was absent [32% (range 20-40) of endothelium intact], predominantly at the side opposed to the anastomosis. CONCLUSION Increasing the laser energy during the ELANA procedure from 10 to 13 mJ does not cause additional acute damage to the vessel wall. Increasing the laser energy from 13 to 15 mJ results in increased acute damage of the endothelium, whereas tunica media and adventitia remain unaffected. Further studies are required to assess the long-term effects of increased laser energy during the ELANA technique.
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Affiliation(s)
- Matthijs Biesbroek
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
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16
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Fromentin S, Sarrazin JF, Champagne J, Nault I, Philippon F, Molin F, Blier L, O’Hara G. Prospective comparison between conventional transseptal puncture and transseptal needle puncture with radiofrequency energy. J Interv Card Electrophysiol 2011; 31:237-42. [DOI: 10.1007/s10840-011-9564-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 03/04/2011] [Indexed: 10/18/2022]
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Fleming CP, Quan KJ, Rollins AM. Toward guidance of epicardial cardiac radiofrequency ablation therapy using optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:041510. [PMID: 20799788 PMCID: PMC2912935 DOI: 10.1117/1.3449569] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 03/18/2010] [Accepted: 03/29/2010] [Indexed: 05/18/2023]
Abstract
Radiofrequency ablation (RFA) is the standard of care to cure many cardiac arrhythmias. Epicardial ablation for the treatment of ventricular tachycardia has limited success rates due in part to the presence of epicardial fat, which prevents proper rf energy delivery, inadequate contact of ablation catheter with tissue, and increased likelihood of complications with energy delivery in close proximity to coronary vessels. A method to directly visualize the epicardial surface during RFA could potentially provide feedback to reduce complications and titrate rf energy dose by detecting critical structures, assessing probe contact, and confirming energy delivery by visualizing lesion formation. Currently, there is no technology available for direct visualization of the heart surface during epicardial RFA therapy. We demonstrate that optical coherence tomography (OCT) imaging has the potential to fill this unmet need. Spectral domain OCT at 1310 nm is employed to image the epicardial surface of freshly excised swine hearts using a microscope integrated bench-top scanner and a forward imaging catheter probe. OCT image features are observed that clearly distinguish untreated myocardium, ablation lesions, epicardial fat, and coronary vessels, and assess tissue contact with catheter-based imaging. These results support the potential for real-time guidance of epicardial RFA therapy using OCT imaging.
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Affiliation(s)
- Christine P Fleming
- Case Western Reserve University, Biomedical Engineering Department, Cleveland, Ohio 44106, USA
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18
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Fleming CP, Quan KJ, Wang H, Amit G, Rollins AM. In vitro characterization of cardiac radiofrequency ablation lesions using optical coherence tomography. OPTICS EXPRESS 2010; 18:3079-92. [PMID: 20174138 DOI: 10.1364/oe.18.003079] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Currently, cardiac radiofrequency ablation (RFA) is guided by indirect signals. We demonstrate optical coherence tomography (OCT) characterization of RFA lesions within swine ventricular wedges. Untreated tissue exhibited a consistent birefringence artifact within OCT images due to the organized myocardium, which was not present in treated tissue. Birefringence artifacts were detected by filtering with a Laplacian of Gaussian (LoG) to quantify gradient strength. The gradient strength distinguished RFA lesions from untreated sites (p=5.93 x 10(-15)) with a sensitivity and specificity of 94.5% and 86.7% respectively. This study demonstrates the potential of OCT for monitoring cardiac RFA, confirming lesion formation and providing feedback to avoid complications.
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Affiliation(s)
- Christine P Fleming
- Case Western Reserve University. Biomedical Engineering Department. Cleveland, OH 44106, USA
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Lequerica JL, Sanz E, Hornero F, Herrero M, Ruiz N, Burdío F, Berjano EJ. Esophagus histological analysis after hyperthermia-induced injury: Implications for cardiac ablation. Int J Hyperthermia 2009; 25:150-9. [DOI: 10.1080/02656730802537626] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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20
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Whittaker P, Przyklenk K. Fibrin architecture in clots: a quantitative polarized light microscopy analysis. Blood Cells Mol Dis 2008; 42:51-6. [PMID: 19054699 DOI: 10.1016/j.bcmd.2008.10.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 10/01/2008] [Indexed: 12/26/2022]
Abstract
Fibrin plays a vital structural role in thrombus integrity. Thus, the ability to assess fibrin architecture has a potential to provide insight into thrombosis and thrombolysis. Fibrin has an anisotropic molecular structure, which enables it to be seen with polarized light. Therefore, we aimed to determine if automated polarized light microscopy methods of quantifying two structural parameters; fibrin fiber bundle orientation and fibrin's optical retardation (OR: a measure of molecular anisotropy) could be used to assess thrombi. To compare fibrin fiber bundle orientation we analyzed picrosirius red-stained sections obtained from clots formed: (A) in vitro, (B) in injured and stenotic coronary arteries, and (C) in surgically created aortic aneurysms (n=6 for each group). To assess potential changes in OR, we examined fibrin in picrosirius red-stained clots formed after ischemic preconditioning (10 min ischemia+10 min reflow; a circumstance shown to enhance lysability) and in control clots (n=8 each group). The degree of fibrin organization differed significantly according to the location of clot formation; fibrin was most aligned in the aneurysms and least aligned in vitro whereas fibrin in the coronary clots had an intermediate organization. The OR of fibrin in the clots formed after ischemic preconditioning was lower than that in controls (2.9+/-0.5 nm versus 5.4+/-1.0 nm, P<0.05). The automated polarized light analysis methods not only enabled fibrin architecture to be assessed, but also revealed structural differences in clots formed under different circumstances.
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Affiliation(s)
- Peter Whittaker
- Cardiovascular Research Institute, Department of Emergency Medicine, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
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21
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Wright JL, Postma DS, Kerstjens HAM, Timens W, Whittaker P, Churg A. Airway remodeling in the smoke exposed guinea pig model. Inhal Toxicol 2007; 19:915-23. [PMID: 17849276 DOI: 10.1080/08958370701515563] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Although small airway remodeling (SAR) leading to airflow obstruction is a common consequence of human cigarette smoking, the airways have been largely ignored in animal models of chronic obstructive pulmonary disease (COPD). We examined lung structure in a guinea pig model of chronic cigarette smoke exposure to ascertain whether smoke induced SAR, and to evaluate how these anatomic lesions correlate with physiologic changes. We used tissue from guinea pigs exposed to cigarette smoke or air for 6 mo. Pulmonary function tests were performed, and histologic sections were prepared. Airspace size (Lm) and changes in the structure of the small airways were evaluated by morphometric analysis. Chronic smoke exposure was associated with increased airway wall thickness and increased amounts of thick collagen fibers in the walls of the small airways, as well as with increased Lm. The increase in thick collagen fibers related negatively to peak expiratory volume (PEF) and the ratio of forced expiratory volume in 1 s to forced ventilatory capacity (FEV(0.1)/FVC), and positively to airway resistance. Physiologic lung volumes were predicted by airspace size, but residual volume (RV) and total lung capacity (TLC) also were related to airway wall thickness. Amounts of smooth muscle were not changed and did not predict any physiologic abnormalities. We conclude that cigarette smoke exposure results in SAR in the guinea pig, alterations that are reflected in increased airways resistance with diminished airflow and air trapping, mimicking human disease. This model should prove useful in further investigations into the mechanisms of airway remodeling.
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Affiliation(s)
- J L Wright
- Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada.
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22
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Wells JD, Thomsen S, Whitaker P, Jansen ED, Kao CC, Konrad PE, Mahadevan-Jansen A. Optically mediated nerve stimulation: Identification of injury thresholds. Lasers Surg Med 2007; 39:513-26. [PMID: 17659590 DOI: 10.1002/lsm.20522] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVE Transient optical nerve stimulation is a promising new non-contact, spatially precise, artifact-free neural excitation technique useful in research and clinical settings. This study evaluates safety of this pulsed infrared laser technique by histopathologic examination of stimulated peripheral nerves. STUDY DESIGN/MATERIALS AND METHODS Exposed rat sciatic nerves were functionally stimulated with the pulsed Holmium:YAG laser, previously validated as an effective tool for optical stimulation. Nerves were removed immediately and up to 2 weeks after stimulation and assessed histologically for thermal damage. Laser parameters studied include upper limits for radiant exposure, repetition rate, and duration of stimulation. RESULTS Radiant exposures with <1% probability of thermal tissue damage (0.66-0.70 J/cm(2)) are significantly greater than radiant exposures required for reliable stimulation (0.34-0.48 J/cm(2)). The upper limit for safe laser stimulation repetition rate occurs near 5 Hz. Maximum duration for constant low repetition rate stimulation (2 Hz) is approximately 4 minutes with adequate tissue hydration. CONCLUSION Results confirm that optical stimulation has the potential to become a powerful non-contact clinical and research tool for brief nerve stimulation with low risk of nerve thermal damage.
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Affiliation(s)
- Jonathon D Wells
- Department of Biomedical Engineering, Vanderbilt University, Box 351631 Station B, Nashville, Tennessee 37235, USA
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Gold MH, Goldman MP, Rao J, Carcamo AS, Ehrlich M. Treatment of Wrinkles and Elastosis Using Vacuum-Assisted Bipolar Radiofrequency Heating of the Dermis. Dermatol Surg 2007; 33:300-9. [PMID: 17338687 DOI: 10.1111/j.1524-4725.2007.33064.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Reduction of wrinkles is increasingly becoming one of the most sought after aesthetic procedures. A variety of treatment modalities are available for this application, including radiofrequency energy in various modes of action. OBJECTIVE The goal of the reported study was to evaluate the safety and efficacy of a new device, which implements an innovative combination of bipolar radiofrequency and vacuum. METHODS Forty-six healthy adults at two clinics underwent eight facial treatments every 1 to 2 weeks. For 6 months after treatment, patients were assessed directly by two evaluators at each clinic (the treating physician and an additional reviewer) using standard evaluation tools-the Fitzpatrick-Goldman Classification of Wrinkling and Degree of Elastosis and a visual analog scale. RESULTS Significant improvement in the skin's appearance and texture was observed during the treatment course and continued to increase during the follow-up period. The mean elastosis score on the wrinkling and elastosis scale before treatment was 4.5 and was reduced to less than 2.5 by 6 months after treatment, representing a drop of an entire wrinkle class (from II to I) on this scale. The reported pain levels were low, and the subjects expressed their satisfaction with the treatment and its outcome. The adverse responses consisted mainly of transient erythema and burn/blistering; there were also a few occurrences of edema, purpura, and crusting and one transient hyperpigmentation. No permanent complications had occurred. CONCLUSIONS Our results demonstrate the safety and efficacy associated with use of this radiofrequency and vacuum device, employing Functional Aspiration Controlled Electrothermal Stimulation (FACES) technology, for reduction of facial wrinkles and elastosis.
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Affiliation(s)
- Michael H Gold
- Gold Skin Care Center and Tennessee Clinical Research Center, Nashville, Tennessee, USA
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24
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Treatment of Wrinkles and Elastosis Using Vacuum-Assisted Bipolar Radiofrequency Heating of the Dermis. Dermatol Surg 2007. [DOI: 10.1097/00042728-200703000-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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25
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Berjano EJ. Theoretical modeling for radiofrequency ablation: state-of-the-art and challenges for the future. Biomed Eng Online 2006; 5:24. [PMID: 16620380 PMCID: PMC1459161 DOI: 10.1186/1475-925x-5-24] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 04/18/2006] [Indexed: 01/09/2023] Open
Abstract
Radiofrequency ablation is an interventional technique that in recent years has come to be employed in very different medical fields, such as the elimination of cardiac arrhythmias or the destruction of tumors in different locations. In order to investigate and develop new techniques, and also to improve those currently employed, theoretical models and computer simulations are a powerful tool since they provide vital information on the electrical and thermal behavior of ablation rapidly and at low cost. In the future they could even help to plan individual treatment for each patient. This review analyzes the state-of-the-art in theoretical modeling as applied to the study of radiofrequency ablation techniques. Firstly, it describes the most important issues involved in this methodology, including the experimental validation. Secondly, it points out the present limitations, especially those related to the lack of an accurate characterization of the biological tissues. After analyzing the current and future benefits of this technique it finally suggests future lines and trends in the research of this area.
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Affiliation(s)
- Enrique J Berjano
- Center for Research and Innovation on Bioengineering, Valencia Polytechnic University, Camino de Vera s/n, 46022 Valencia, Spain.
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26
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Deng CX, Qu F, Nikolski VP, Zhou Y, Efimov IR. Fluorescence imaging for real-time monitoring of high-intensity focused ultrasound cardiac ablation. Ann Biomed Eng 2006; 33:1352-9. [PMID: 16240084 DOI: 10.1007/s10439-005-6806-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2004] [Accepted: 06/22/2005] [Indexed: 11/28/2022]
Abstract
Side effects and limitations of radio-frequency ablation of cardiac arrhythmias prompted search for alternative energy sources and means of their application. High-intensity focused ultrasound (HIFU) is becoming an increasingly attractive modality for ablation because of its unique ability for non-invasive or minimally invasive, non-contact focal ablation in 3D volume without affecting intervening and surrounding cells. The purpose of this study is to develop a real-time monitoring technique to elucidate HIFU-induced modifications of electrical conduction in cardiac tissues and to investigate the HIFU cardiac ablation process to help to achieve optimal HIFU ablation outcome. We conducted experimental studies applying HIFU at 4.23 MHz to ablate the atrio-ventricular (AV) node and ventricular tissue of Langendorff-perfused rabbit hearts. We employed fluorescent voltage-sensitive dye imaging and surface electrodes to monitor the electrical conduction activity induced by HIFU application in real time. In ventricular epicardium HIFU ablation, fluorescent imaging revealed gradual reduction of the plateau phase and amplitude of the action potential. Subsequently, conduction block and cell death were observed at the site of ablation. When HIFU was applied to the AV node, fluorescent imaging and electrograms revealed the development of the AV block. The study establishes that real-time fluorescent imaging provides novel monitoring and assessment to study HIFU cardiac ablation, which may be able to provide improved understanding of HIFU cardiac ablation process and mechanism useful for development of successful clinical applications.
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Affiliation(s)
- Cheri X Deng
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106-7207, USA.
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27
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Parsons JE, Cain CA, Abrams GD, Fowlkes JB. Pulsed cavitational ultrasound therapy for controlled tissue homogenization. ULTRASOUND IN MEDICINE & BIOLOGY 2006; 32:115-29. [PMID: 16364803 DOI: 10.1016/j.ultrasmedbio.2005.09.005] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 09/09/2005] [Accepted: 09/14/2005] [Indexed: 05/05/2023]
Abstract
Methods were investigated to acoustically control the extent to which cavitation-mediated tissue homogenization is responsible for lesion formation in vitro. These results may guide potential therapeutic procedures that induce damage predominantly via mechanical disruption and, thereby, avoid limitations associated with thermal ablative modalities. Porcine myocardium was insonified at 750 kHz using pulse sequences consisting of high-amplitude pulses (22 MPa Pr) interleaved with variable-amplitude "sustaining" pulses (e.g., 6.9 MPa Pr), which were intended to provide sufficient acoustic input to maintain cavitation activity between primary pulses, but to increase the spatial peak temporal average intensity (I(SPTA)) only marginally. Using modest temporal-average intensities (e.g., I(SPTA) approximately 200 W/cm2), approximately 0.5 cm3 lesions were produced consisting of homogenate that could be irrigated away to reveal smooth cavities. The prevalence of homogenate in a given lesion was sensitive to both pulse-repetition frequency and sustaining pulse amplitude, suggesting the existence of optimum acoustic parameters for producing homogenized lesions largely via mechanical perturbation.
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Affiliation(s)
- Jessica E Parsons
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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Wells PB, Thomsen S, Jones MA, Baek S, Humphrey JD. Histological evidence for the role of mechanical stress in modulating thermal denaturation of collagen. Biomech Model Mechanobiol 2005; 4:201-10. [PMID: 16261328 DOI: 10.1007/s10237-005-0002-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 06/14/2005] [Indexed: 12/01/2022]
Abstract
The hyperthermia and thermal denaturation literatures reveal a time-temperature equivalency when heating cells or connective tissues: thermal damage increases with increasing temperature (for the same duration) and increases with increasing duration (for the same temperature). Recent findings conversely suggest that increasing the mechanical loading on a tissue during heating decreases the thermal damage (for a given temperature and duration of heating). Surprisingly, however, there are few histological correlates of such damage. In this paper, we show that progressive light microscopic changes - swelling of collagen bands, thickening of collagen-rich layers, hyalinization, and loss of birefringence approximately - correlate very well with both increased heating times and decreased mechanical loading. Increased mechanical stress is thus thermally protective and should be considered in the design of clinical procedures that use heating to treat diseases or injuries.
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Affiliation(s)
- P B Wells
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843, USA
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Deguchi JO, Aikawa E, Libby P, Vachon JR, Inada M, Krane SM, Whittaker P, Aikawa M. Matrix metalloproteinase-13/collagenase-3 deletion promotes collagen accumulation and organization in mouse atherosclerotic plaques. Circulation 2005; 112:2708-15. [PMID: 16230484 DOI: 10.1161/circulationaha.105.562041] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Interstitial collagen plays a crucial structural role in arteries. Matrix metalloproteinases (MMPs), including MMP-13/collagenase-3, likely contribute to collagen catabolism in atherosclerotic plaques. METHODS AND RESULTS To test the hypothesis that a specific MMP-collagenase influences the development and structure of atherosclerotic plaques, this study used atherosclerosis-susceptible apolipoprotein E-deficient mice that lack MMP-13/collagenase-3 (Mmp-13(-/-)/apoE(-/-)) or express wild-type MMP-13/collagenase-3 (Mmp-13(+/+)/apoE(-/-)). Both groups consumed an atherogenic diet for 5 (n=8) or 10 weeks (n=9). Histological analyses of the aortic root of both groups revealed similar plaque size and accumulation of smooth muscle cells (a collagen-producing cell type) and macrophages (a major source of plaque collagenases) after 5 and 10 weeks of atherogenic diet. By 10 weeks, the plaques of Mmp-13(-/-)/apoE(-/-) mice contained significantly more interstitial collagen than those of Mmp-13(+/+)/apoE(-/-) mice (P<0.01). Furthermore, quantitative optical analyses revealed thinner and less aligned periluminal collagen fibers within the plaques of Mmp-13(+/+)/apoE(-/-) mice versus those from Mmp-13(-/-)/apoE(-/-) mice. CONCLUSIONS These data support the hypothesis that MMP-13/collagenase-3 plays a vital role in the regulation and organization of collagen in atherosclerotic plaques.
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Affiliation(s)
- Jun-O Deguchi
- Donald W. Reynolds Cardiovascular Clinical Research Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Veinot JP, Lemery R. Innovations in cardiovascular pathology: anatomic and electrophysiologic determinants associated with ablation of atrial arrhythmias. Cardiovasc Pathol 2005; 14:204-13. [PMID: 16009319 DOI: 10.1016/j.carpath.2005.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Revised: 02/01/2005] [Accepted: 02/04/2005] [Indexed: 10/25/2022] Open
Abstract
The pathologist is required to evaluate hearts and surgical specimens following innovative therapies to ablate arrhythmias. For the treatment or cure of atrial fibrillation, ablation of the pulmonary vein sleeves and left atrium is increasingly encountered. The recognized contribution of the right atrium, Bachmann's bundle and other sites such as the vein of Marshall and epicardial ganglia has given rise to specific procedures to target these areas. Improved and safe power sources are needed to achieve these goals. Catheters and devices have been developed using different energy types to create therapeutic lesions. The pathologist will encounter different sources of energy and catheter and probe device modifications for surgical and catheter-based endocardial and epicardial therapy. This article reviews the pathology of ablation and the recent innovations in the treatment of atrial arrhythmias.
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Affiliation(s)
- John P Veinot
- Division of Anatomical Pathology, Department of Laboratory Medicine, Ottawa Hospital, Ontario, Canada.
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31
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Deneke T, Khargi K, Müller KM, Lemke B, Mügge A, Laczkovics A, Becker AE, Grewe PH. Histopathology of intraoperatively induced linear radiofrequency ablation lesions in patients with chronic atrial fibrillation. Eur Heart J 2005; 26:1797-803. [PMID: 15855195 DOI: 10.1093/eurheartj/ehi255] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Radiofrequency (RF) energy has been extensively used in ablation of arrhythmia but so far no analysis of morphological effects in human left atria has been conducted. METHODS AND RESULTS We studied 59 ablation lesions from seven patients who died 2 to 22 days after open heart surgery plus intraoperative cooled-tip RF ablation to treat permanent atrial fibrillation (AF) (mean 4, 1-11 years). The ablation area was studied by macroscopy and histological analysis. RF ablation produced clearly delineated coagulation necrosis (up to a depth of 5.5 mm) bordered by an irregular zone of incomplete necrosis and fresh bleeding even 22 days post-operatively. No superficial charring, thrombotic deposition, or perforation was documented. Endocardium and subendocardium displayed oedematic loosening and microfragmentation of connective tissue fibres. Early after ablation (2-6 days), interfibrillar disseminated bleeding and necrosis without tissue removal response were found. Later after ablation (21, 22 days), mild inflammatory reaction and granulation tissue appeared. Twenty-five per cent of all studied lesions, especially in the thick region in between left pulmonary veins and mitral annulus (left atrial isthmus) (86%), were non-transmural. Nerve fibres with different degrees of thermal injury were detected in the pulmonary vein ostial region. CONCLUSION Intraoperative cooled-tip ablation in AF resulted in coagulation necrosis of endocardium, subendocardium, and the atrial myocardial layer to a depth of 5.5 mm bordered by an irregular zone of incomplete thermal damage. Transmurality of the lesions could only be found in 75% of intraoperatively applied lesions.
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Affiliation(s)
- Thomas Deneke
- Medical Clinic II (Cardiology and Angiology), BG Kliniken Bergmannsheil, Ruhr-University Bochum, Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany.
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Rem AI, Oosterhuis JA, Keunen JEE, Journée-De Korver HG. Transscleral thermotherapy with laser-induced and conductive heating in hamster Greene melanoma. Melanoma Res 2005; 14:409-14. [PMID: 15457098 DOI: 10.1097/00008390-200410000-00012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to investigate the cytotoxic effect of heat as induced by transscleral thermotherapy (TSTT), which may be of interest in the treatment of patients with choroidal melanoma. The aim of TSTT is to heat both the sclera and the tumor up to a cytotoxic temperature of about 60 degrees C. TSTT was performed in hamsters with subcutaneously implanted Greene melanoma covered by a specimen of human donor sclera of thickness 0.5, 0.7 or 0.9 mm. A newly developed applicator, which combines conductive episcleral heating at 60 degrees C with laser-induced heating, was used at laser powers ranging from 500 to 1500 mW delivered by an 810 nm diode laser, beam diameter 3 mm, and exposure time 1 min. Temperatures were measured at the scleral surface and at the sclera-tumor interface. The extent of tumor necrosis was examined by light microscopy and the sclera was examined by polarized light microscopy. Maximal depth of tumor necrosis without scleral damage was 4.4 (SD 1.5) mm. The temperature at the scleral surface after TSTT was 58.8 (SD 2.4) degrees C. The temperature at the sclera-tumor interface ranged from 56.4 (SD 3.7) degrees C at 500 mW to 65.3 (SD 4.4) degrees C at 1250 mW laser power. Structural changes to the scleral collagen started to develop at 1250 mW. TSTT with combined laser-induced and conductive heating caused cytotoxic temperatures in the tumor and the sclera, which were well tolerated by the scleral collagen.
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Affiliation(s)
- Alex I Rem
- Department of Ophthalmology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
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Veldtman GR, Wilson GJ, Peirone A, Hartley A, Estrada M, Norgard G, Leung RK, Visram N, Benson LN. Radiofrequency perforation and conventional needle percutaneous transseptal left heart access: Pathological features. Catheter Cardiovasc Interv 2005; 65:556-63. [PMID: 16010688 DOI: 10.1002/ccd.20328] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Perforating radiofrequency (PRF) energy has been used to obtain percutaneous transseptal left heart access. Contrary to ablative radiofrequency (RF), myocardial tissue responses to PRF thermal injury are incompletely defined. In this study, a newly developed RF catheter system for transseptal left atrial entry was compared with conventional needle puncture. Of 15 piglets having transfemoral cardiac catheterization, 12 had transseptal procedures. Needle punctures (NP) and PRF were followed by acute (1 hr; 3 NP, 3 PRF) and chronic necropsy (1 month; 3 NP, 3 PRF). The remaining three piglets had intentional RF aortic perforation through the atrial roof with necropsy at 1 month. Gross and histopathological effects were examined. Acutely, the gross RF lesion was similar to needle puncture. Histologically, the RF lesions had minimal mural thrombus, an inner zone of thermal injury characterized by grayish cytoplasmic staining (elastic trichrome), and a bubbly transformation of the cytoplasm in innermost cardiomyocytes, partial persistence of cross-striations, and an acute inflammatory reaction. The outer extent of the lesion (< 1 mm) was defined by a halo of contraction band necrosis similar to needle puncture. Acute NP injury showed comparable depth and extent of myocyte necrosis (principally contraction bands) with adjacent tissue hemorrhage and edema. At 1 month, a well-developed densely collagenous scar was present in both aortic and transseptal PRF lesions. The extent of acute RF injury is similar to that seen in conventional NP, but the characteristics of tissue insult are different. Both show well-developed healing at 1 month.
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Affiliation(s)
- Gruschen R Veldtman
- Department of Pediatrics, Division of Cardiology, Hospital for Sick Children, University of Toronto School of Medicine, Ontario, Canada
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Bridges CR, Horvath KA, Nugent WC, Shahian DM, Haan CK, Shemin RJ, Allen KB, Edwards FH. The Society of Thoracic Surgeons practice guideline series: transmyocardial laser revascularization. Ann Thorac Surg 2004; 77:1494-502. [PMID: 15063304 DOI: 10.1016/j.athoracsur.2004.01.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/14/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND Patients with chronic severe angina refractory to medical therapy who cannot be completely revascularized with either percutaneous catheter intervention or coronary artery bypass graft surgery present clinical challenges. Transmyocardial laser revascularization, either as sole therapy or as an adjunct to coronary artery bypass graft surgery, may be appropriate for some of these patients. Although transmyocardial revascularization has consistently been demonstrated as an efficacious means of relieving angina, the mechanism of its effects are still debated, and criteria for the selection of patients for this novel therapy have not been adequately defined. METHODS We reviewed the available evidence to allow us to make recommendations for the appropriate therapeutic applications of transmyocardial revascularization following the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. Our recommendations were classified as class I, IIA, IIB, or III. For each recommendation we defined the level of supporting evidence as A, B, or C. RESULTS We identified class I indications for transmyocardial revascularization as sole therapy and class IIA indications for transmyocardial revascularization as an adjunct to coronary artery bypass graft surgery with levels of evidence A and B, respectively. CONCLUSIONS Transmyocardial laser revascularization may be an acceptable form of therapy for selected patients: as sole therapy for a subset of patients with refractory angina and as an adjunct to coronary artery bypass graft surgery for a subset of patients with angina who cannot be completely revascularized surgically.
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Affiliation(s)
- Charles R Bridges
- Division of Cardiothoracic Surgery, Department of Surgery, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA.
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Lazebnik RS, Breen MS, Fitzmaurice M, Nour SG, Lewin JS, Wilson DL. Radio-frequency-induced thermal lesions: Subacute magnetic resonance appearance and histological correlation. J Magn Reson Imaging 2003; 18:487-95. [PMID: 14508786 DOI: 10.1002/jmri.10382] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate the relationship between subacute magnetic resonance (MR) images of radio-frequency (RF) ablation lesions and tissue viability as determined from histological tissue samples. MATERIALS AND METHODS We generated lesions (N = 5) in a rabbit thigh model. Four days later, we obtained in vivo T(2)- and contrast-enhanced (CE) T(1)-weighted images and ex vivo histological samples approximately perpendicular to the electrode path. Using three-dimensional registration and warping, we spatially compared manually segmented boundaries apparent on MR images to boundaries separating distinct histological zones determined from hematoxylin and eosin (H&E) and Masson trichrome (MT) stains, as well as birefringence studies. RESULTS Lesions have a characteristic MR appearance: an outer hyperintense margin (M2) separating background tissue (M3) from an inner core (M1), in both T(2) and CE T(1) images. Histologically, there are two zones of damage: an outer zone of likely nonviable cells (H2) separating background tissue (H3) from an inner core of coagulated nonviable cells (H1). We measured distances between automatically computed correspondence points along histological and MR boundaries. For T(2) and CE T(1) images, respectively, M1 vs. H1 distances were 0.72 +/- 0.99 mm (mean +/- SD) and 0.10 +/- 0.95 mm, while outer M2 vs. H2 boundary distances were 0.26 +/- 1.16 mm and 0.05 +/- 1.08 mm. The discrepancy between histological and MR boundaries was larger than the variability in segmenting MR images, but probably within registration error. There were no significant differences between T(2) and CE T(1) boundaries. CONCLUSION Lesion boundaries apparent in both T(2)- and CE T(1)-weighted MR scans, performed several days postablation, similarly predict the histological response. That is, the lesion core (M1) corresponds to nonviable coagulated cells (H1), while the hyperintense margin (M2) corresponds to likely nonviable cells undergoing necrotic changes (H2).
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Affiliation(s)
- Roee S Lazebnik
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Dietz U, Horstick G, Manke T, Otto M, Eick O, Kirkpatrick CJ, Meyer J, Darius H. Myocardial angiogenesis resulting in functional communications with the left cavity induced by intramyocardial high-frequency ablation: histomorphology of immediate and long-term effects in pigs. Cardiology 2003; 99:32-8. [PMID: 12589120 DOI: 10.1159/000068450] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2002] [Indexed: 11/19/2022]
Abstract
A previous study in rabbit hearts demonstrated the feasibility of creating transmyocardial channels by application of temperature-regulated high-frequency (HF) energy. Feasibility of creating non-transmural channels using a transvascular approach was tested in 14 pigs which were followed for 1 h, and 3 and 9 weeks (group A, B and C). Myocardial channels were found to be highly reproducible and patent in more than two thirds in group A. Channels were replaced by connective tissue during follow-up which contained newly formed small vessels. A functional communication between the left ventricular cavum and newly formed vessels of the channel remnants could be demonstrated in one heart of group C. Thus, intramyocardial HF ablation can be performed with high reproducibility to induce local angiogenesis.
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Affiliation(s)
- Ulrich Dietz
- German Clinic for Diagnostics, Wiesbaden, Germany.
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Whittaker P, Müller-Ehmsen J, Dow JS, Kedes LH, Kloner RA. Development of abnormal tissue architecture in transplanted neonatal rat myocytes. Ann Thorac Surg 2003; 75:1450-6. [PMID: 12735561 DOI: 10.1016/s0003-4975(02)04995-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND Most myocardial cell transplant studies focus on demonstration of improved function; however, such improvement depends on the development of appropriate tissue structure. Thus, our aim was to assess the architectural changes that occurred after cell transplant into normal and infarcted myocardium. METHODS Male neonatal cells (1 to 2 days old) were injected into the left ventricular free wall of adult female rats. The tissue was examined 0 to 1 days and 1 to 2, 4 to 6, and 12 weeks later in noninfarcted hearts and 6 months after transplant into infarcts. In histologic sections, we assessed the cells' retardation of polarized light (to measure development of contractile elements), two-dimensional cell orientation, cell nuclear morphology, and collagen content. RESULTS The transplant cells' retardation of polarized light gradually increased to 81% of that of host cells after 6 months (p < 0.001). The transplant cells were disorganized and although their nuclei increased in size, they always had a rounded appearance. Collagen content in the transplant was 210% to 430% higher than in host tissue (p < 0.01). In addition, scar collagen always separated transplant and host cells. CONCLUSIONS One architectural feature, the rounded nuclei, provided a distinctive marker to identify transplanted cells. Nevertheless, the transplants' inhibited muscle development together with disorganization, separation from the host muscle, and a substantial increase in collagen resulted in a structure unlikely to play an active role in systolic function.
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Affiliation(s)
- Peter Whittaker
- Department of Emergency Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
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Manasse E, Colombo PG, Barbone A, Braidotti P, Bulfamante G, Roincalli M, Gallotti R. Clinical histopathology and ultrastructural analysis of myocardium following microwave energy ablation. Eur J Cardiothorac Surg 2003; 23:573-7. [PMID: 12694778 DOI: 10.1016/s1010-7940(02)00835-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE Due to weaknesses of conventional modes for treating atrial fibrillation (AF), surgical energy ablation methods and tools to cure AF have been under rapid development. One of these methods, microwave energy, is beginning to be applied clinically. The purpose of this study was to examine histology and ultrastructure of lesions produced by microwave energy in the myocardium. METHODS Fifteen consecutive patients underwent surgical microwave energy ablation (Microwave Ablation System with FLEX 4 probe, AFx Inc., Fremont, CA) concomitant to a valve procedure. Epicardial ablation was carried out on the beating normothermic heart prior to performing the valve procedure. Two tissue specimens (1cm(2)) were obtained from each patient; one from the lesion site (right appendage) and the other from an adjacent, non-ablated site, which was used as control. Tissue samples were fixed and stained as appropriate for histological and ultrastructural analysis. RESULTS All ablated samples revealed observable microscopic alteration, including loss of nuclei, foci of coagulative necrosis or induced irregular bands of contraction. Ultrastructurally, ablated cells demonstrated architectural disarray, loss of contractile filaments, mitochondrial swelling and focal interruption of plasma membrane. CONCLUSIONS Histologic appearance of lesions created by epicardial microwave energy ablation was consistent over tissue samples, although acute findings demonstrated differences from cryoablation. In most of the cases, lesions were transmural, as was demonstrated by loss of cellular viability throughout the depth of tissue specimens.
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Affiliation(s)
- E Manasse
- Cardiac Surgery Department, Istituto Clinico Humanitas, University of Milan School of Medicine, Rozzano, Milan, Italy.
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Díaz De Tuesta I, Martínez R. [Coronary artery bypass graft combined with transmyocardial laser revascularization. Survival and functional class at one-year follow-up]. Rev Esp Cardiol 2001; 54:1295-304. [PMID: 11707240 DOI: 10.1016/s0300-8932(01)76500-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION AND OBJECTIVES The use of Transmyocardial Laser Revascularization (TMLR) as a strategy to treat unstable angina has been reported in many studies. We analyze its safety and effectiveness in combined procedures (CABG + TMLR). METHODS A non-randomized, retrospective cohort study was performed from May 4, 1999 to May 25, 2000 in 21 TMLR patients (18 combined CABG + TMLR) and 118 CABG only procedures. Mortality and NYHA analyses were determined by telephone at follow-up. RESULTS Three hospital deaths were observed: one isolated TMLR patient, one valvular + CABG + TMLR patient, and one CABG + TMLR patient. A significantly higher incidence of preoperative angina was found in the group of patients with TMLR + CABG, than in the group with only CABG (83 vs 25%; p < 0.001). There were no differences in age, gender, ejection fraction, Parsonnet and EuroSCORE risk estimation, or mortality (5.1% isolated CABG, 5.6% combined). No episode of angina was detected during follow-up in the CABG + TMLR group: 88% patients were NYHA I, and 21% NYHA II. CONCLUSION Incomplete coronary revascularization may be complemented with TMLR in the areas in which CABG is not possible without increased mortality. This technique may avoid postoperative unstable angina due to residual ischemic areas.
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Affiliation(s)
- I Díaz De Tuesta
- Hospital Universitario de Canarias, 38190 La L aguna, SC Tenerife.
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Kavanagh GJ, Whittaker P, Prejean CA, Firth BR, Kloner RA, Kay GL. Dissociation between improvement in angina pectoris and myocardial perfusion after transmyocardial revascularization with an excimer laser. Am J Cardiol 2001; 87:229-31, A9. [PMID: 11152849 DOI: 10.1016/s0002-9149(00)01326-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Xenon chloride excimer laser transmyocardial revascularization significantly reduced angina in all patients and increased regional myocardial perfusion in most patients; however, there was no correlation between symptomatic improvement and flow improvement. Patients' symptomatic improvement preceded improved perfusion by several months.
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Affiliation(s)
- G J Kavanagh
- Department of Nuclear Medicine, The Heart Institute, Good Samaritan Hospital, Los Angeles, California 90017, USA
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