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Nyns ECA, Portero V, Deng S, Jin T, Harlaar N, Bart CI, van Brakel TJ, Palmen M, Hjortnaes J, Ramkisoensing AA, Zhang GQ, Poelma RH, Ördög B, de Vries AAF, Pijnappels DA. Light transmittance in human atrial tissue and transthoracic illumination in rats support translatability of optogenetic cardioversion of atrial fibrillation. J Intern Med 2023; 294:347-357. [PMID: 37340835 DOI: 10.1111/joim.13654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
BACKGROUND Optogenetics could offer a solution to the current lack of an ambulatory method for the rapid automated cardioversion of atrial fibrillation (AF), but key translational aspects remain to be studied. OBJECTIVE To investigate whether optogenetic cardioversion of AF is effective in the aged heart and whether sufficient light penetrates the human atrial wall. METHODS Atria of adult and aged rats were optogenetically modified to express light-gated ion channels (i.e., red-activatable channelrhodopsin), followed by AF induction and atrial illumination to determine the effectivity of optogenetic cardioversion. The irradiance level was determined by light transmittance measurements on human atrial tissue. RESULTS AF could be effectively terminated in the remodeled atria of aged rats (97%, n = 6). Subsequently, ex vivo experiments using human atrial auricles demonstrated that 565-nm light pulses at an intensity of 25 mW/mm2 achieved the complete penetration of the atrial wall. Applying such irradiation onto the chest of adult rats resulted in transthoracic atrial illumination as evidenced by the optogenetic cardioversion of AF (90%, n = 4). CONCLUSION Transthoracic optogenetic cardioversion of AF is effective in the aged rat heart using irradiation levels compatible with human atrial transmural light penetration.
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Affiliation(s)
- Emile C A Nyns
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Vincent Portero
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Shanliang Deng
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Tianyi Jin
- Department of Microelectronics, Delft University of Technology, Delft, the Netherlands
| | - Niels Harlaar
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Cindy I Bart
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | | | - Meindert Palmen
- Department of Cardiothoracic Surgery, LUMC, Leiden, the Netherlands
| | - Jesper Hjortnaes
- Department of Cardiothoracic Surgery, LUMC, Leiden, the Netherlands
| | - Arti A Ramkisoensing
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Guo Qi Zhang
- Department of Microelectronics, Delft University of Technology, Delft, the Netherlands
| | - René H Poelma
- Department of Microelectronics, Delft University of Technology, Delft, the Netherlands
| | - Balázs Ördög
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center (LUMC), Leiden, the Netherlands
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Majumder R, Hussaini S, Zykov VS, Luther S, Bodenschatz E. Pulsed low-energy stimulation initiates electric turbulence in cardiac tissue. PLoS Comput Biol 2021; 17:e1009476. [PMID: 34624017 PMCID: PMC8528298 DOI: 10.1371/journal.pcbi.1009476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/20/2021] [Accepted: 09/23/2021] [Indexed: 11/18/2022] Open
Abstract
Interruptions in nonlinear wave propagation, commonly referred to as wave breaks, are typical of many complex excitable systems. In the heart they lead to lethal rhythm disorders, the so-called arrhythmias, which are one of the main causes of sudden death in the industrialized world. Progress in the treatment and therapy of cardiac arrhythmias requires a detailed understanding of the triggers and dynamics of these wave breaks. In particular, two very important questions are: 1) What determines the potential of a wave break to initiate re-entry? and 2) How do these breaks evolve such that the system is able to maintain spatiotemporally chaotic electrical activity? Here we approach these questions numerically using optogenetics in an in silico model of human atrial tissue that has undergone chronic atrial fibrillation (cAF) remodelling. In the lesser studied sub-threshold illumination régime, we discover a new mechanism of wave break initiation in cardiac tissue that occurs for gentle slopes of the restitution characteristics. This mechanism involves the creation of conduction blocks through a combination of wavefront-waveback interaction, reshaping of the wave profile and heterogeneous recovery from the excitation of the spatially extended medium, leading to the creation of re-excitable windows for sustained re-entry. This finding is an important contribution to cardiac arrhythmia research as it identifies scenarios in which low-energy perturbations to cardiac rhythm can be potentially life-threatening.
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Affiliation(s)
| | - Sayedeh Hussaini
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
- Institute for Dynamics of Complex Systems, University of Göttingen, Göttingen, Germany
| | - Vladimir S Zykov
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Stefan Luther
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
- Institute for Dynamics of Complex Systems, University of Göttingen, Göttingen, Germany
| | - Eberhard Bodenschatz
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
- Laboratory of Atomic and Solid-State Physics and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, United States of America
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Vivekanandan S, Landau DB, Counsell N, Warren DR, Khwanda A, Rosen SD, Parsons E, Ngai Y, Farrelly L, Hughes L, Hawkins MA, Fenwick JD. The Impact of Cardiac Radiation Dosimetry on Survival After Radiation Therapy for Non-Small Cell Lung Cancer. Int J Radiat Oncol Biol Phys 2017; 99:51-60. [PMID: 28816160 PMCID: PMC5554783 DOI: 10.1016/j.ijrobp.2017.04.026] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/07/2017] [Accepted: 04/19/2017] [Indexed: 12/17/2022]
Abstract
PURPOSE The heart receives high radiation doses during radiation therapy of advanced-stage lung cancer. We have explored associations between overall survival, cardiac radiation doses, and electrocardiographic (ECG) changes in patients treated in IDEAL-CRT, a trial of isotoxically escalated concurrent chemoradiation delivering tumor doses of 63 to 73 Gy. METHODS AND MATERIALS Dosimetric and survival data were analyzed for 78 patients. The whole heart, pericardium, AV node, and walls of left and right atria (LA/RA-Wall) and ventricles (LV/RV-Wall) were outlined on radiation therapy planning scans, and differential dose-volume histograms (dDVHs) were calculated. For each structure, dDVHs were approximated using the average dDVH and the 10 highest-ranked structure-specific principal components (PCs). ECGs at baseline and 6 months after radiation therapy were analyzed for 53 patients, dichotomizing patients according to presence or absence of "any ECG change" (conduction or ischemic/pericarditis-like change). All-cause death rate (DR) was analyzed from the start of treatment using Cox regression. RESULTS 38% of patients had ECG changes at 6 months. On univariable analysis, higher scores for LA-Wall-PC6, Heart-PC6, "any ECG change," and larger planning target volume (PTV) were significantly associated with higher DR (P=.003, .009, .029, and .037, respectively). Heart-PC6 and LA-Wall-PC6 represent larger volumes of whole heart and left atrial wall receiving 63 to 69 Gy. Cardiac doses ≥63 Gy were concentrated in the LA-Wall, and consequently Heart-PC6 was highly correlated with LA-Wall-PC6. "Any ECG change," LA-Wall-PC6 scores, and PTV size were retained in the multivariable model. CONCLUSIONS We found associations between higher DR and conduction or ischemic/pericarditis-like changes on ECG at 6 months, and between higher DR and higher Heart-PC6 or LA-Wall-PC6 scores, which are closely related to heart or left atrial wall volumes receiving 63 to 69 Gy in this small cohort of patients.
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Affiliation(s)
- S Vivekanandan
- Department of Oncology and CRUK MRC, Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford, UK
| | - D B Landau
- Department of Oncology, Guy's & St. Thomas' NHS Trust, King's College London, UK
| | - N Counsell
- Cancer Research UK & UCL Cancer Trials Centre Cancer Institute, University College London, London, UK
| | - D R Warren
- Department of Oncology and CRUK MRC, Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford, UK
| | - A Khwanda
- Department of Cardiology, Ealing Hospital and Imperial College London, UK
| | - S D Rosen
- Department of Cardiology, Ealing and Royal Brompton Hospitals & Imperial College, London, UK
| | - E Parsons
- Radiotherapy Trials Quality Assurance, Mount Vernon Hospital, Middlesex, UK
| | - Y Ngai
- Cancer Research UK & UCL Cancer Trials Centre Cancer Institute, University College London, London, UK
| | - L Farrelly
- Cancer Research UK & UCL Cancer Trials Centre Cancer Institute, University College London, London, UK
| | - L Hughes
- Cancer Research UK & UCL Cancer Trials Centre Cancer Institute, University College London, London, UK
| | - M A Hawkins
- Department of Oncology and CRUK MRC, Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford, UK.
| | - J D Fenwick
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Liverpool, UK; Department of Physics, Clatterbridge Cancer Centre, Wirral, UK
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Tyran M, Mailleux H, Tallet A, Fau P, Gonzague L, Minsat M, Moureau-Zabotto L, Resbeut M. Volumetric-modulated arc therapy for left-sided breast cancer and all regional nodes improves target volumes coverage and reduces treatment time and doses to the heart and left coronary artery, compared with a field-in-field technique. J Radiat Res 2015; 56:927-937. [PMID: 26386255 PMCID: PMC4628222 DOI: 10.1093/jrr/rrv052] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 08/04/2015] [Accepted: 08/07/2015] [Indexed: 06/05/2023]
Abstract
We compared two intensity-modulated radiotherapy techniques for left-sided breast treatment, involving lymph node irradiation including the internal mammary chain. Inverse planned arc-therapy (VMAT) was compared with a forward-planned multi-segment technique with a mono-isocenter (MONOISO). Ten files were planned per technique, delivering a 50-Gy dose to the breast and 46.95 Gy to nodes, within 25 fractions. Comparative endpoints were planning target volume (PTV) coverage, dose to surrounding structures, and treatment delivery time. PTV coverage, homogeneity and conformality were better for two arc VMAT plans; V95%(PTV-T) was 96% for VMAT vs 89.2% for MONOISO. Homogeneity index (HI)(PTV-T) was 0.1 and HI(PTV-N) was 0.1 for VMAT vs 0.6 and 0.5 for MONOISO. Treatment delivery time was reduced by a factor of two using VMAT relative to MONOISO (84 s vs 180 s). High doses to organs at risk were reduced (V30(left lung) = 14% using VMAT vs 24.4% with MONOISO; dose to 2% of the volume (D2%)(heart) = 26.1 Gy vs 32 Gy), especially to the left coronary artery (LCA) (D2%(LCA) = 34.4 Gy vs 40.3 Gy). However, VMAT delivered low doses to a larger volume, including contralateral organs (mean dose [Dmean](right lung) = 4 Gy and Dmean(right breast) = 3.2 Gy). These were better protected using MONOISO plans (Dmean(right lung) = 0.8 Gy and Dmean(right breast) = 0.4 Gy). VMAT improved PTV coverage and dose homogeneity, but clinical benefits remain unclear. Decreased dose exposure to the LCA may be clinically relevant. VMAT could be used for complex treatments that are difficult with conventional techniques. Patient age should be considered because of uncertainties concerning secondary malignancies.
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Affiliation(s)
- Marguerite Tyran
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Hugues Mailleux
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Agnes Tallet
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Pierre Fau
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Laurence Gonzague
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Mathieu Minsat
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Laurence Moureau-Zabotto
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
| | - Michel Resbeut
- Service de Radiothérapie, Institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, 13009 Marseille, France
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Xie X, Lee SW, Johnson C, Ippolito J, KenKnight BH, Tolkacheva EG. Intermittent vagal nerve stimulation alters the electrophysiological properties of atrium in the myocardial infarction rat model. Annu Int Conf IEEE Eng Med Biol Soc 2014; 2014:1575-1578. [PMID: 25570272 DOI: 10.1109/embc.2014.6943904] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Intermittent vagal nerve stimulation (VNS) has emerged as a potential therapy to treat cardiovascular diseases by delivering electrical stimulation to the vagus nerves. The purpose of this study was to investigate the electrophysiological changes in the atrium resulting from long-term intermittent VNS therapy in the chronic myocardial infarction (MI) rat model. MI was induced via left anterior descending coronary artery (LAD) ligation in male Sprague-Dawley rats, randomized into two groups: MI (implanted with nonfunctional VNS stimulators) and MI-VNS (implanted with functional VNS stimulators and received chronic intermittent VNS treatment) groups. Further, a sham group was used as control in which MI was not performed and received nonfunctional VNS stimulators. At 12 weeks, optical mapping of right atrium (RA) of sinus rhythm was performed. Our results demonstrated that chronic MI changed the electrical properties of the atrium action potentials and resulted in reduced action potential duration at 50% (APD50) and 80% (APD80) repolarization. Chronic right cervical VNS restored the APD back to healthy heart APD values. Additionally, APD heterogeneity index increased as a result of the chronic MI. Chronic VNS was not found to alter this increase. By calculating PR intervals from weekly ECG recordings of anaesthetized rats, we demonstrated that chronic MI and intermittent VNS did not affect the AV conduction time from the atria to the ventricles. From our study, we conclude the MI decreased the APD and increased APD spatial dispersion. VNS increased the APD back to healthy normal values but did change the APD spatial dispersion and the electrical conduction in the RA.
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Novotny M, Quaiserova-Mocko V, Wehrwein EA, Kreulen DL, Swain GM. Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection. J Neurosci Methods 2007; 163:52-9. [PMID: 17383009 PMCID: PMC2679869 DOI: 10.1016/j.jneumeth.2007.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2006] [Revised: 02/12/2007] [Accepted: 02/12/2007] [Indexed: 12/27/2022]
Abstract
Capillary electrophoresis with end-column amperometric detection (CE-EC) was used to determine the regional distribution of norepinephrine (NE) in the hearts of sympathetically innervated (control) and chemically sympathectomized rats. Key features of the method are (i) the sample preparation and clean-up step that involved the application of off-line solid phase extraction (SPE) with a 95% NE recovery and (ii) the use of a diamond microelectrode for detection. NE was quantified in the left and right ventricle, the ventricular septum, and the left and right atrium. The NE concentration in the atria was three to five times higher than in the ventricles and ventricular septum of control rats. Basal NE levels in the left and right ventricle and the ventricular septum were reduced to below the detection limit (0.034 microg/g tissue) in tissues treated with the neurotoxin, 6-hydroxydopamine (6-OHDA), while only a moderate reduction was observed in the left and right atrium. Importantly, the diamond microelectrode provided low and stable background current and low peak-to-peak noise <or=0.65 pA at a detection potential of +0.86 V versus Ag/AgCl. A reproducible electrode response was observed for multiple injections of tissue homogenates with minimal response attenuation due to electrode fouling.
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Affiliation(s)
- Martin Novotny
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Veronika Quaiserova-Mocko
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Erica A. Wehrwein
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - David L. Kreulen
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
| | - Greg M. Swain
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
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Gaynor SL, Byrd GD, Diodato MD, Ishii Y, Lee AM, Prasad SM, Gopal J, Berube D, Schuessler RB, Damiano RJ. Dose response curves for microwave ablation in the cardioplegia-arrested porcine heart. Heart Surg Forum 2006; 8:E331-6. [PMID: 16099735 DOI: 10.1532/hsf98.20051011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Microwave ablation has been used clinically for the surgical treatment of atrial fibrillation, particularly during valve procedures. However, dose- response curves have not been established for this surgical environment. The purpose of this study was to examine dosimetry curves for the Flex 4 and Flex 10 microwave devices in an acute cardioplegia-arrested porcine model. METHODS Twelve domestic pigs (40-45 kg) were acutely subjected to Flex 4 (n = 6) and Flex 10 (n = 6) ablations. On a cardioplegically arrested heart maintained at 10-15(o)C, six endocardial atrial and seven epicardial ventricular lesions were created in each animal. Ablations were performed for 15 s, 30 s, 45 s, 60 s, 90 s, 120 s, and 150 s (65 W, 2.45 GHz). The tissue was stained with 2,3,5-triphenyl-tetrazolium chloride and lesions were sectioned at 5 mm intervals. Lesion depth and width were determined from digital photomicrographs of each lesion (resolution +/- .03 mm). RESULTS Average atrial thickness was 2.88 +/- .4 mm (range 1.0 to 8.0 mm). 94% of ablated atrial sections created by the FLEX 4 (n = 16) and the FLEX 10 (n = 16) were transmural at 45 seconds. 100% of atrial sections were transmural at 90 seconds with the FLEX 10 (n = 14) and at 60 seconds with the Flex 4 device (n = 15). Lesion width and depth increased with duration of application. CONCLUSION Both devices were capable of producing transmural lesions on the cardioplegically arrested heart at 65 W. These curves will allow surgeons to ensure transmural ablation by tailoring energy delivery to the specific atrial geometry.
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Affiliation(s)
- Sydney L Gaynor
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Xu Z, Fowlkes JB, Cain CA. A new strategy to enhance cavitational tissue erosion using a high-intensity, Initiating sequence. IEEE Trans Ultrason Ferroelectr Freq Control 2006; 53:1412-24. [PMID: 16921893 PMCID: PMC2676890 DOI: 10.1109/tuffc.2006.1665098] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Our previous studies have shown that pulsed ultrasound can physically remove soft tissue through cavitation. A new strategy to enhance the cavitation-induced erosion is proposed wherein tissue erosion is initiated by a short, high-intensity sequence of pulses and sustained by lower intensity pulses. We investigated effects of the initiating sequence on erosion and cavitation sustained by lower intensity pulses. Multiple three-cycle pulses at a pulse repetition frequency of 20 kHz delivered by a 788-kHz focused transducer were used for tissue erosion. Fixing the initiating sequence at I(SPPA) of 9000 W/cm2, 16 combinations of different numbers of pulses within the initiating sequence and different sustaining pulse intensities were tested. Results showed: the initiating sequence increases the probability of erosion occurrence and the erosion rate with only slight overall increases in propagated energy; the initiating sequence containing more pulses does not increase the sustained cavitation period; and if extinguished and reinitiated, the sustained cavitation period becomes shorter after each initiation, although the waiting time between adjacent cavitation periods is random. The high-intensity, initiating sequence enhances cavitational tissue erosion and enables erosion at intensities significantly lower than what is required to initiate erosion.
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Affiliation(s)
- Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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Guerra PG, Talajic M, Thibault B, Dubuc M, Roy D, Macle L, Leung TK, Arsenault A, Harel F, Grégoire J, Bonan R. β-Radiation for the Creation of Linear Lesions in the Canine Atrium. Circulation 2004; 110:911-4. [PMID: 15302779 DOI: 10.1161/01.cir.0000139865.39885.03] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Creating linear lesions is important for the treatment of arrhythmias such as atrial flutter and fibrillation. Making these lesions with standard radiofrequency catheters can be difficult and may result in charring and thrombosis. The purpose of this study was to evaluate β-radiation as a novel energy source for creating linear myocardial lesions.
Methods and Results—
Eight dogs with intact conduction across the cavotricuspid isthmus were studied. The isthmus was irradiated (25 to 50 Gy) with strontium/yttrium-90 delivered via a deflectable 7F catheter (Novoste Corporation). There were no immediate effects, but bidirectional conduction block developed during follow-up studies in 7 of 8 dogs. The dog without conduction block received 25 Gy. After the animals were euthanized, histology revealed transmural, linear areas of fibrosis without any thrombus.
Conclusions—
β-Radiation can safely and effectively create linear lesions that are contiguous and nonthrombogenic. This energy source may become an interesting adjunct to radiofrequency for the treatment of atrial flutter and fibrillation.
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Affiliation(s)
- Peter G Guerra
- Department of Medicine and Research Center, Montreal Heart Institute, 5000 Belanger East, Montreal, Quebec, Canada H1T 1C8.
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Abstract
Epicardial radiofrequency ablation is increasingly being used for intraoperative treatment of atrial fibrillation. However, the effect of different parameters on the lesion characteristics has not been sufficiently characterized. We used a finite element model to calculate the temperature distribution in the atrial tissue under different conditions during a constant voltage radiofrequency ablation. Our simulation results show that although in the case of a thin atrium the lesion was less deep for a thin atrium, it was easier to achieve transmurality. While considering a thinner atrium, the location of the hottest point of the lesion shifted from the electrode tip to epicardial surface. This effect was due to the convective cooling of the circulating blood inside the atrium. This convective cooling phenomenon has almost negligible effects for atria thicker than 3 mm. The variability of the cooling values has no significant effect on the lesion, even for thin atria (1-2 mm). Increasing the electrode insertion depth (ID) in the tissue produced larger lesions. However, for thinner atria (thickness <2 mm), this increase in the ID reduced the lesion width. It was also proved that the presence of a fat layer between the electrode and the atrial tissue decreased significantly the lesion dimensions.
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Affiliation(s)
- Enrique J Berjano
- Departamento de Ingeniería Electrónica, Universidad Politécnica de Valencia Camino de Vera s/n, Valencia, Spain.
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Abstract
The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm2, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.
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Affiliation(s)
- Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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Xu Z, Ludomirsky A, Eun LY, Hall TL, Tran BC, Fowlkes JB, Cain CA. Controlled ultrasound tissue erosion. IEEE Trans Ultrason Ferroelectr Freq Control 2004; 51:726-736. [PMID: 15244286 DOI: 10.1109/tuffc.2004.1304271] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm2, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.
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Affiliation(s)
- Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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15
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Tabuena RP, Matsumoto H, Mio T, Nagata Y, Mishima M. Metastatic tumor in the right atrium. Intern Med 2004; 43:445-6. [PMID: 15206563 DOI: 10.2169/internalmedicine.43.445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Rollin P Tabuena
- Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University
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16
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Kruse JJCM, Strootman EG, Bart CI, Visser A, Leer JWH, Wondergem J. Radiation-induced changes in gene expression and distribution of atrial natriuretic peptide (ANP) in different anatomical regions of the rat heart. Int J Radiat Biol 2002; 78:297-304. [PMID: 12020441 DOI: 10.1080/09553000110102021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To examine the effects of whole-heart irradiation on gene expression and distribution of atrial natriuretic peptide (ANP) in atrial appendages and left ventricles of the rat heart. MATERIAL AND METHODS Female Sprague-Dawley rats were irradiated with a single dose of 0, 15 or 20 Gy locally to the heart. At intervals up to 16 months post-irradiation, the localization of ANP was examined using immunohistochemical techniques. Absolute mRNA concentrations were determined using the competitive PCR assay. RESULTS Histological and immunohistochemical studies demonstrated that whole-heart irradiation caused a reduction of atrial ANP, which is due to a substantial loss of ANP-producing atrial myocytes and accumulation of collagen (replacement fibrosis). On the other hand, ANP became detectable in the subendocardium of the irradiated left ventricles. Positive staining of ANP was mainly found in the proximity of injured areas consisting of degeneration of myocytes and fibrosis. At the transcriptional level, reduction of atrial ANP expression at 1 month post-irradiation was followed by recovery at 3 months. Thereafter, ANP mRNA concentrations followed the mRNA pattern of controls and even appeared to increase at 16 months. In the left ventricle, dose-dependent and progressive elevation of ANP gene expression could be observed during the observation period and reached a 20-fold increase as compared with sham-irradiated age-matched controls. CONCLUSIONS The distribution of ANP after local irradiation of the rat heart depends on the severity of the pathological/structural changes (i.e. myocyte degeneration and fibrosis). In radiation-induced heart disease, elevated ANP expression in the left ventricle is most probably involved in the observed chronic elevation of plasma ANP levels.
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Affiliation(s)
- J J C M Kruse
- Department of Experimental Therapy, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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Krüse JJ, Zurcher C, Strootman EG, Bart CI, Schlagwein N, Leer JW, Wondergem J. Structural changes in the auricles of the rat heart after local ionizing irradiation. Radiother Oncol 2001; 58:303-11. [PMID: 11230892 DOI: 10.1016/s0167-8140(00)00327-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE Irradiation of the heart may lead to late cardiovascular complications and depending on the dose to cardiac-related death. There is increasing evidence that left atrial appendages play an important role in left ventricular filling especially in cardiac disease. The aim of the present study was to investigate the radiation response of the atria of the rat heart (auricles in particular) at morphological, histological and transcriptional level. MATERIAL AND METHODS Sprague-Dawley rats were irradiated with a single dose locally on the heart (0-22.5 Gy). End-diastolic diameters of left auricles were measured during evaluation of cardiac function. Histopathological evaluations were performed at various time points up to 16 months post irradiation. Changes in mRNA expression of procollagen types I and III and pro-fibrogenic cytokines (TGF-beta1 and IL-1beta) were investigated using competitive PCR. RESULTS Irradiation leads to a dose-dependent decrease in end-diastolic diameter of the left auricles. This decrease was observed at 4 months post-irradiation, where no gross damage of the ventricle has been reported. Histologically, epicardial fibrosis was found already 1 month post irradiation, and the frequency/severity of the structural changes appeared to be dose-dependent and progressive with time post irradiation. At 9 months, fibrosis was observed in all three layers (epicardium, myocardium and endocardium) of both auricles. On the level of gene expression, increases in procollagen types I and III were observed at 12 and 3 months post irradiation, respectively. Increases in IL-1beta and TGF-beta1, cytokines known to influence collagen deposition at different levels, preceded the upregulation of procollagen mRNA. CONCLUSIONS Auricles of the rat heart show a marked pathological response to ionizing radiation, characterized by generalized accumulation of collagen (fibrosis) and a reduction of end-diastolic diameter. The reduction of auricular volume and loss of elasticity will negatively contribute to the pump function of the irradiated ventricle.
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Affiliation(s)
- J J Krüse
- Department of Clinical Oncology, University Hospital Leiden (LUMC), Leiden, The Netherlands
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Kubota H, Takamoto S, Takeshita M, Miyaji K, Kotsuka Y, Furuse A. Atrial ablation using an IRK-151 infrared coagulator in canine model. J Cardiovasc Surg (Torino) 2000; 41:835-47. [PMID: 11232966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
BACKGROUND A method of atrial ablation was developed with the aim of shortening the aortic cross-clamp time during MAZE surgery. The IRK-151 infrared coagulator (Infrarot-Kontaktkoagulator: MBB: Messerschmidt-Bolkow-Blohn, Germany) was employed. Our aim was to electrophysiologically confirm the efficacy of this device. METHODS The MAZE-III procedure was performed in four mongrel dogs. Instead of a pulmonary vein-encircling incision, IRK-151 was applied several times to create a continuously overlapping circular lesion. After aortic declamping, the potentials of both atria were recorded using 18 bipolar electrodes implanted in the atrial wall. The recording conditions were: 1) sinus rhythm, 2) overdrive pacing from outside the encircling coagulation, and 3) overdrive pacing from inside the encircling coagulation. RESULTS 1) There was no detectable potential within the pulmonary vein-encircling coagulation. 2) There was no conduction of paced atrial potential inside the encircling coagulation. 3) Only the area within the encircling coagulation was activated by the stimulus. Other parts of the atrium showed sinus rhythm simultaneously. CONCLUSIONS The left atrium within the pulmonary vein-encircling coagulation was isolated electrophysiologically.
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Affiliation(s)
- H Kubota
- Department of Cardiothoracic Surgery, University of Tokyo, Japan
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Fox AD, Banning AP, Channon K, Hands L. Saddle embolus of the carotid bifurcation. A late complication of mediastinal radiotherapy. Eur J Vasc Endovasc Surg 1999; 17:360-2. [PMID: 10204061 DOI: 10.1053/ejvs.1998.0649] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- A D Fox
- Nuffield Department of Surgery, John Radcliffe Hospital, Headington, Oxford, U.K
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Mikhaĭlova SD, Sokolov AV, Semushkina TM, Storozhakov GI. [Participation of sympathetic innervation of the heart in the antiarrhythmic effect of intra-atrial laser irradiation]. Biull Eksp Biol Med 1998; 126:522-6. [PMID: 9883359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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21
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Mikhaĭlova SD, Kudinova AV, Semushkina TM, Storozhakov GI. [Response of bulbar cardiovascular and respiratory neurons to intra-auricular laser irradiation]. Biull Eksp Biol Med 1998; 125:263-5. [PMID: 9606538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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22
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Mikhaĭlova SD, Storozhakov GI, Semushkina TM, Stepaniuk NN, Sokolov AV. [Dependence of the antiarrhythmic effect of laser radiation on power, duration, and site of action]. Biull Eksp Biol Med 1995; 119:246-8. [PMID: 7795186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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23
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Pellegrini A, Soldani P, Paparelli A, Breschi MC, Scatizzi R, Nieri P, Campagni A, Del Bianchi S. Noradrenergic innervation and receptor responses of cardiovascular tissues from young and aged rats after acute microwave exposure. Int J Neurosci 1994; 76:165-75. [PMID: 7960475 DOI: 10.3109/00207459408986001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Young and senescent rats were exposed to 2,450 GHz microwaves for 45' and the effects of this treatment on the noradrenergic pattern and beta-cardiac and alpha-aortic receptorial functions were evaluated. In young animals, an increase in noradrenergic innervation was observed, while no functional modification was shown. In aged rats the increase in fluorescent fibers was almost the same as that observed in young rats, but significant variations in functional responses were found. Both at atrial and ventricular levels responses to the beta-agonist isoprenaline were unmodified in their affinity indices, but showed a marked decrease in the maximal responses; by contrast the activity of noradrenaline on the aortic alpha-adrenoceptors showed a great increase in maximal response without changes in the pD2 values. These results suggest that the predominant effect of microwave exposure consists in an increase in the noradrenergic pattern, and this effect is not related to the functional modifications.
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MESH Headings
- Aging
- Animals
- Aorta, Abdominal/innervation
- Aorta, Abdominal/radiation effects
- Cardiovascular System/innervation
- Cardiovascular System/radiation effects
- Dose-Response Relationship, Radiation
- Environmental Exposure
- Heart/innervation
- Heart/radiation effects
- Heart Atria/innervation
- Heart Atria/radiation effects
- Heart Ventricles/innervation
- Heart Ventricles/radiation effects
- Isoproterenol/pharmacology
- Male
- Microwaves
- Muscle, Smooth, Vascular/innervation
- Muscle, Smooth, Vascular/radiation effects
- Norepinephrine/physiology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, beta/physiology
- Receptors, Adrenergic, beta/radiation effects
- Sympathetic Nervous System/anatomy & histology
- Sympathetic Nervous System/radiation effects
- Thermodynamics
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Affiliation(s)
- A Pellegrini
- Istituto di Anatomia Umana Normale, Facoltà di Medicina e Chirurgia, Università di Pisa, Italy
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Schwartz JL, Mealing GA. Calcium-ion movement and contractility in atrial strips of frog heart are not affected by low-frequency-modulated, 1 GHz electromagnetic radiation. Bioelectromagnetics 1993; 14:521-33. [PMID: 8297396 DOI: 10.1002/bem.2250140604] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Calcium efflux from electrically stimulated, 45Ca(2+)-preloaded atrial strips of the frog heart was measured from samples of the rinsing perfusate collected at 2-min intervals for 32 min in a continuous perfusion chamber. Contractile force was simultaneously monitored. The specimen chamber was located in a stripline apparatus in which the atrial strips were exposed for 32 min to constant (CW) or amplitude-modulated (AM), 1 GHz electromagnetic (EM) fields at specific absorption rates (SAR) ranging from 3.2 microW/kg to 1.6 W/kg. Amplitude modulation was either at 0.5 Hz, in synchrony with the electrical stimulus applied to the preparation, or at 16 Hz. Neither unmodulated nor 0.5 Hz or 16 Hz modulated 1 GHz waves affected the movement of calcium ions or the contractile force in isolated atrial strips of the frog heart.
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Affiliation(s)
- J L Schwartz
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec
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Mikhaĭlova SD, Storozhakov GI, Gukova SI, Semushkina TM. [Mechanism of the antiarrhythmic effect of laser irradiation]. Biull Eksp Biol Med 1992; 113:460-2. [PMID: 1421248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Acute experiments were performed to study the role of afferent impulses from the heart receptors which pass by different vagal fibers during intraatrial laser irradiation. Double laser irradiation of the right atrium seemed more effective than a single one as to decreasing ventricular arrhythmias during cardiac ischemia. It is shown that the antiarrhythmic effect of intraatrial laser irradiation may be due to the change of the afferent information passing by myelinated vagal fibers.
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Shilov VV, Lobanok LM. [Modification of the chronotropic-inotropic relations in the atrial and ventricular myocardium during external gamma-irradiation]. Radiobiologiia 1991; 31:432-5. [PMID: 1887014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
It has been shown of isolated muscle preparations of rat heart that external gamma-irradiation with a dose of 6 Gy reduces the contractile capacity of myocardium and changes the chronoinotropic relationships: in the auricle, the rate/power relationship and the potentiating effect of the passive interval increase, and in the ventricles, the potentiating effect decreases. Modification of the chronoinotropic relationships may be associated with changes in the calcium ion transport in the heart cells.
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Abstract
Varying values for the acetylcholine (ACh) concentration in the rat heart have been reported. The possibility that the method of sampling may influence prompted a comparison of heart levels of ACh obtained by two different procedures for sacrificing animals. One method was by microwave irradiation in vivo and the others being in vitro on the irradiated heart removed after decapitation. There were significant differences found in cardiac ACh concentration between the in vivo irradiated group and the decapitation groups. In decapitated animals, the cardiac ACh concentration became increasingly lower on standing. We also measured the ACh concentration of right atrium, left atrium, right ventricle and left ventricle. They were 4.62 +/- 1.57 nmol/g (mean +/- SD), 2.58 +/- 1.01, 2.76 +/- 1.00 and 2.12 +/- 0.70, respectively. We conclude the microwave irradiation in vivo is a more appropriate method for determining the cardiac ACh concentration.
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Affiliation(s)
- A Nomura
- Department of Cardiovascular Medicine, School of Medicine, Hokkaido University, Sapporo, Japan
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Barnes M, Pass H, DeLuca A, Tochner Z, Potter D, Terrill R, Sindelar WF, Kinsella TJ. Response of the mediastinal and thoracic viscera of the dog to intraoperative radiation therapy (IORT). Int J Radiat Oncol Biol Phys 1987; 13:371-8. [PMID: 3104247 DOI: 10.1016/0360-3016(87)90011-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
IORT may be a potentially useful adjunctive treatment combined with surgery and/or external beam irradiation in treating locally advanced lung and esophageal tumors. To begin investigation of this modality, the tolerance of intact mediastinal structures to IORT was studied using adult American Foxhounds (wt. 25-30 kg). Groups of six animals received IORT to doses of 20, 30, or 40 Gy to two separate intrathoracic ports, using 9 MeV electrons to treat a portion of the collapsed right upper lobe, and 12 MeV electrons to treat the mediastinal structures. A group of three dogs received thoracotomy with sham irradiation. Two dogs from each treatment dose group, as well as one sham-irradiated control, were sacrificed electively at 1, 3, and 12 months following IORT. There were no acute nor late IORT related mortalities. Post-operative weight loss was minimal (average 4.5% of pre-operative weight) for all dogs. Serial esophagrams showed no inflammation or ulceration. No cardiac nor pulmonary changes were noted clinically. At autopsy, the irradiated lung showed evidence of acute pneumonitis at 1 month with progressive fibrosis at 3 months and 1 year. Esophageal reactions were minimal, with only two dogs (one 30 Gy and one 40 Gy) demonstrating histologically confirmed esophagitis at 1 month. Tracheal changes were minimal. Cardiac damage was evident in the right atrial tissues. In several dogs, this cardiac damage ranged from myocardial vascular changes to frank ischemic necrosis noted at 1 and 3 months, and dense fibrosis at 1 year. The phrenic nerves showed normal function, but had evidence of perineural fibrosis. The large vessels demonstrated only mild histologic evidence of irradiation. The results of this large animal study suggest that intact mediastinal structures will tolerate small volume IORT to doses of 20 Gy without significant clinical sequellae. Although the histologic changes in the right atrium and contralateral lung are worrisome, no cardiac nor pulmonary problems arose over the 1 year follow-up. Irradiation of the contralateral lung and other sensitive structures can be reduced by careful selection of electron beam energy and use of custom lead shielding.
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Abstract
The chronotropic and inotropic effects of 2.45-GHz continuous wave (CW) microwave radiation were investigated in the isolated spontaneously beating rat atria. Isolated atria were placed in specially designed tubes inserted into a waveguide exposure system. The atria were then irradiated for a period of 30 min, followed by a 30-min recovery period. The control atria were prepared simultaneously and sham exposed. Experiments were conducted at two temperatures, 22 and 37 degrees C, and two specific absorption rates, 2 mW/g and 10 mW/g. At both temperatures the rate of atrial contraction was not altered by a 30-min exposure at either 2 or 10 mW/g. The average rate (beats per min) was approximately 100 for both the control and exposed atria at 22 degrees C and 215 beats per min for both the control and exposed atria at 37 degrees C. In addition, no inotropic effects on the spontaneously beating atria were noted at any exposure level. These data suggest that 2.45-GHz CW microwave radiation at these intensities has no overt effect on these variables in isolated rat atria.
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Stryker JA, Lee KJ, Abt AB. The effects of X radiation on the canine heart. Radiat Res 1980; 82:200-10. [PMID: 7367589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Prignitz R, Hoffmeister G. [Influence of x-rays on electrolyte shifts and myocardial metabolism. 3. Radiation-induced changes of magnesium concentration in isolated guinea pig atrium]. Strahlentherapie 1973; 146:693-700. [PMID: 4209764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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