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1
Oeding, Matthew. "Defibrillation safety." Thesis, Oeding, Matthew (2012) Defibrillation safety. Other thesis, Murdoch University, 2012. https://researchrepository.murdoch.edu.au/id/eprint/13113/.
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In the past years, there has been a dramatic transition between the use of older monophasic defibrillators to newer, more sophisticated, biphasic types. As these biphasic defibrillators are more efficient, they require less energy and therefore create less of a risk to bystanders. Due to the lack of research around these new defibrillators, the current recommended procedures may not accurately reflect the safety of medical personnel. Because of this, the recommended “all clear” period may in fact become detrimental to the health of the patient as it causes the cessation of crucial activities of medical staff such as IV canalization and chest compressions. This thesis is aimed at assisting in a study to be performed by the Professor of Emergency Medicine at Royal Perth Hospital by designing a device capable of measuring, storing and analyzing the leakage voltages from a patient and their environment whilst undergoing defibrillation.
The device that was designed consisted of a data acquisition system that would measure the voltages using standard ECG leads, and then wirelessly transmit that data to a laptop for further processing. Throughout the entire design process, the focus was aimed at ensuring the device would meet all the criteria specified in the required standards and cause no detrimental effect to the patient being monitored. At the end of the thesis period, a functional schematic was designed and tested, ready for manufacture as well as a solid framework of the software component of the project.
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McKeown, Paschal Patrick Joseph. "Transoesophageal cardioversion and defibrillation." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334471.
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Darragh, K. M. "Optimisation of Defibrillation for Ventricular Fibrillation." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527675.
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Harbinson, Mark Thomas. "Studies in atrial and ventricular defibrillation." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361286.
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Caldwell, Jane Cochrane. "Ventricular fibrillation in ischaemia and its defibrillation." Thesis, University of Glasgow, 2006. http://theses.gla.ac.uk/6196/.
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ECG signals were recorded from isolated, Langendorff-perfused rabbit hearts to establish the relationship between dominant frequency and myocardial perfusion during ventricular fibrillation. Lower perfusion rates produced faster rates of dominant frequency decline, to lower steady state values. Optically mapping the anterior epicardial surface demonstrated heterogeneity of dominant frequency in ventricular fibrillation. During low-flow ischaemia, the dominant frequency reduction was restricted to the left ventricle. Application of individual ischaemic components during ventricular fibrillation demonstrated that raised [K+]EC, but not hypoxia or acidic pHEC, reproduced the ischaemic reduction of dominant frequency in the ECG, pseudoECG and over the left ventricular epicardial surface. In contrast, minimum defibrillation energies were increased by hypoxia and acidic pHEC, and not by raised [K+]EC. The dominant frequency heterogeneity during ventricular fibrillation in low-flow ischaemia and raised [K+]EC was not due to differential prolongation of repolarisation or post-repolarisation refractoriness in the left ventricle. Monophasic action potential studies showed that APD90 was reduced to similar degrees in each ventricle by low-flow ischaemia and raised [K+]EC. Effective refractory period was not altered in either ventricle by either condition. Low-flow ischaemia decreased conduction velocity in the left, but not the right ventricle. Conduction velocities were unaltered by raised [K+]EC in either ventricle. The activation threshold of the left ventricle was increased in low-flow ischaemia and raised [K+]EC, whilst the threshold of the right ventricle was unchanged. The increased activation threshold was associated with decreased upstroke velocity and diastolic depolarisation.
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Morgan, Stuart William. "Low-Energy Defibrillation Using Resonant Drift Pacing." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507718.
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Huber, Claudia. "Konzeption und Evaluation eines Qualitätsmanagementsystems im Bereich der Frühdefibrillation." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2009/1217/.
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Santos, JoseÌ Angel. "Transcutaneous pulsed mode power delivery to implants for the treatment of atrial fibrillation." Thesis, University of Ulster, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251911.
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Wilson, Carol Mildred. "Studies on cardiac defibrillation : waveform, threshold and damage." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357514.
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Walsh, S. J. "Biphasic waveforms for internal and external atrial defibrillation." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401795.
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Paisey, John R. "Defibrillation, the coronary venous system and the passive electrode affect." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420222.
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Bennett, J. R. "The transvenous defibrillation of ventricular fibrillation using novel shock waveforms." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534636.
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Wong, Po-luk, and 王寶綠. "An evidence-based guideline of defibrillation for cardiac arrest patients." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193065.
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Survival to discharge following a cardiac arrest is dependent on rapid and effective basic and advanced life support. As stated in the latest guideline of the American Heart Association (AHA, 2010), healthcare providers who treat cardiac arrest in hospital should use the defibrillator or other facilities with automated external defibrillators to provide immediate cardiopulmonary resuscitation.
Defibrillation plays an important role in restoring normal electrical rhythm and natural pacemaker control to the heart from chaotic heart rhythm such as ventricular fibrillation or pulseless ventricular tachycardia. This dissertation aims to identify the best evidence and develop an evidence-based guideline of defibrillation for cardiac arrest patients. The objectives of this thesis are to conduct a search of available literatures on defibrillation, mainly focusing on the defibrillation waveform and energy level, perform a critical appraisal on the literature, establish tables of evidence, and develop recommendations and defibrillation protocol for cardiac arrest patients.
A systematic search was performed using four electronic databases, including PubMed, Ovid Medicine, CINAHL and the journal Resuscitation. Six randomized controlled studies were selected from thousands of related studies which fulfilled the inclusion criteria of this dissertation. Data were extracted by tables of evidence and critical appraisal was performed. Also, the level of evidence for each study was graded according to the Scottish Intercollegiate Guidelines Network (SIGN) framework. By synthesizing the data from the six selected studies, the biphasic waveform with 200J as the first shock energy and 200J-300J-360J as subsequent shocks was shown to help to achieve more desirable clinical outcomes to cardiac patients. The implementation potential, including transferability, feasibility and cost/ benefit ratio of the innovation, was assessed, and the evidence-based practice protocol are beneficial for cardiac arrest patients. Also, a comprehensive implementation plan was demonstrated by discussing communication between different stakeholders and transitions the practice from initiation to guiding and sustaining stage. Pilot testing would be carried out to explore any unexpected technical and logistic issues that could be avoided in the full-scale implementation of the innovation. A full evaluation plan concerning patient outcomes, healthcare provider outcomes and system outcomes would then formulated and demonstrated in the end of this dissertation.<br>published_or_final_version<br>Nursing Studies<br>Master<br>Master of Nursing
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Carlisle, Ewan James Frazer. "Studies on ventricular fibrillation : spectral analysis and optimisation of defibrillation." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317020.
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Schönegg, Martin [Verfasser], and A. [Akademischer Betreuer] Bolz. "Impedanzunabhängige Defibrillation mit physiologischer Impulsform / Martin Schönegg. Betreuer: A. Bolz." Karlsruhe : KIT-Bibliothek, 2008. http://d-nb.info/1013805593/34.
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Johnston, Paul Weir. "Transthoracic impedence cardiography : a method of detecting the loss of cardiac output during arrhythmias." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387925.
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Kemper, Michael [Verfasser], and Bernhard [Akademischer Betreuer] Zwißler. "Antizipatorische Ladesequenz der Defibrillation : Vergleich der No-Flow Zeit und Sicherheit der Defibrillation mit dem ERC- Handlungsablauf : eine prospektive, randomisierte Simulatorstudie / Michael Kemper ; Betreuer: Bernhard Zwißler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1213658950/34.
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Uchaipichat, Nopadol. "The prediction of defibrillation outcome using time-frequency power spectrum methods." Thesis, Edinburgh Napier University, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418238.
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Jorgenson, Dawn Blilie. "Optimizing current delivery in defibrillation : finite element models and experimental validation /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/8054.
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Dwyer, Trudy, and t. dwyer@cqu edu au. "A shock in time saves lives: Theory of Planned Behaviour and nurse-initiated defibrillation." Central Queensland University. Nursing and Health Studies, 2004. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20050221.152259.
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The time from onset of a cardiac arrest to defibrillation is crucial hence access to and use of a defibrillator by all nurses essential. The purpose of this study was to use an established theoretical framework to examine and describe the defibrillation practices and beliefs of rural registered nurses in the Australian state of Queensland. The Theory of Reasoned Action (TRA) and Theory of Planned Behaviour (TPB) guided the research processes for this two phase study. In the first phase, focus group (n = 13) discussions identified the salient beliefs of the population. By eliciting nurses' beliefs, the subsequent quantitative study (n = 434) was conducted to determine the influences of these beliefs on nurses' use or non-use of defibrillators. The results showed that: (1) less than half of the cohort of participants were permitted to defibrillate; (2) the defibrillation beliefs of those nurses permitted to defibrillate were significantly more positive than those not permitted to do so; (3) the direct measures of TPB and selected variables external to the model predicted a significant portion of the variance in the measure of nurse-initiated defibrillation intention; and, (4) subjective norm emerged as the strongest predictor of intention. In conclusion, Queensland rural hospital nurses and employers still have some distance to travel down the path of nurse-initiated defibrillation. The TPB is a viable framework on which to base interventions designed to promote defibrillation by rural nurses. Understanding the role of social norms is of central importance to ensure all nurses can initiate the chain of survival expeditiously whenever the need arises.
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Dalzell, Gavin W. N. "Factors involved in synchronised and unsynchronised defibrillation of patients with cardiac disease." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317028.
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Wong, Tee Wee. "The effects of class III antiarrythmic drugs on fibrillation and defibrillation thresholds." Thesis, The University of Sydney, 1997. https://hdl.handle.net/2123/27524.
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The occurrence of ventricular arrhythmias is a serious problem facing patients with coronary artery disease or myocardial infarction. The primary therapy to terminate life—threatening arrhythmias is a direct current shock delivered via the chest area (ie. transthoracic cardiac shock). Although the implantable cardioverter defibrillator has made a major impact on mortality in patients with life—threatening arrhythmias, many of these patients still require adjunctive therapy.
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Ohuchi, Katsuhiro, Yasuhiro Fukui, Ichiro Sakuma, et al. "Computer Simulation Analysis of Shock Intensity - and Phase - Dependence of High-Intensity DC Stimulation Aftereffects on Action Potential of Ventricular Muscle." Research Institute of Environmental Medicine, Nagoya University, 2003. http://hdl.handle.net/2237/7600.
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Kim, Seok Chan. "ELECTROPORATION BY STRONG INTERNAL DEFIBRILLATION SHOCK IN INTACT STRUCTURALLY NORMAL AND CHRONICALLY INFARCTED RABBIT HEARTS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196122659.
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Hamilton, Andrew James. "The effectiveness and cost-effectiveness of a Northern Ireland public access defibrillation project." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527927.
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Bernabeu, Llinares Miguel Oscar. "An open source HPC-enabled model of cardiac defibrillation of the human heart." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:9ca44896-8873-4c91-9358-96744e28d187.
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Sudden cardiac death following cardiac arrest is a major killer in the industrialised world. The leading cause of sudden cardiac death are disturbances in the normal electrical activation of cardiac tissue, known as cardiac arrhythmia, which severely compromise the ability of the heart to fulfill the body's demand of oxygen. Ventricular fibrillation (VF) is the most deadly form of cardiac arrhythmia. Furthermore, electrical defibrillation through the application of strong electric shocks to the heart is the only effective therapy against VF. Over the past decades, a large body of research has dealt with the study of the mechanisms underpinning the success or failure of defibrillation shocks. The main mechanism of shock failure involves shocks terminating VF but leaving the appropriate electrical substrate for new VF episodes to rapidly follow (i.e. shock-induced arrhythmogenesis). A large number of models have been developed for the in silico study of shock-induced arrhythmogenesis, ranging from single cell models to three-dimensional ventricular models of small mammalian species. However, no extrapolation of the results obtained in the aforementioned studies has been done in human models of ventricular electrophysiology. The main reason is the large computational requirements associated with the solution of the bidomain equations of cardiac electrophysiology over large anatomically-accurate geometrical models including representation of fibre orientation and transmembrane kinetics. In this Thesis we develop simulation technology for the study of cardiac defibrillation in the human heart in the framework of the open source simulation environment Chaste. The advances include the development of novel computational and numerical techniques for the solution of the bidomain equations in large-scale high performance computing resources. More specifically, we have considered the implementation of effective domain decomposition, the development of new numerical techniques for the reduction of communication in Chaste's finite element method (FEM) solver, and the development of mesh-independent preconditioners for the solution of the linear system arising from the FEM discretisation of the bidomain equations. The developments presented in this Thesis have brought Chaste to the level of performance and functionality required to perform bidomain simulations with large three-dimensional cardiac geometries made of tens of millions of nodes and including accurate representation of fibre orientation and membrane kinetics. This advances have enabled the in silico study of shock-induced arrhythmogenesis for the first time in the human heart, therefore bridging an important gap in the field of cardiac defibrillation research.
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Arafune, Tatsuhiko, Akira Mishima, Ichiro Sakuma, et al. "Virtual Electrode-induced Spiral Reentry in Ventricular Myocardium Perfused in-vitro." Research Institute of Environmental Medicine, Nagoya University, 2003. http://hdl.handle.net/2237/7602.
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Fotuhi, Parwis. "Tierexperimentelle Untersuchungen zur Therapie und Pathogenese von ventrikulären Herzrhythmusstörungen." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2003. http://dx.doi.org/10.18452/13876.
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Der Plötzliche Herztod ist eine der häufigsten Todesursachen in Europa, in den USA sogar die häufigste Ursache aller natürlichen Todesfälle. Ziel der experimentellen und klinischen Forschung ist das Erkennen und Verhindern ("Prediction and Prevention") der malignen Herzrhythmusstörungen. Schwerpunkt der wissenschaftlichen Arbeit bilden die experimentellen Untersuchungen hinsichtlich der Mechanismen von Herzrhythmusstörungen. Durch die Entwicklung neuartiger Mappingsysteme konnte erstmalig gezeigt werden, dass im Tiermodell Kammerflimmern initial fokal und geordnet entsteht. Die bisherigen Untersuchungen und Daten erweitern unser Wissen zur kardialen Defibrillation und zum Entstehen von malignen Herzrhythmusstörungen, stellen aber nur einen Baustein im Gesamtverständnis des Plötzlichen Herztodes dar. Weitere begonnene oder geplante Projekte beschäftigen sich mit Herzrhythmusstörungen bei Vorliegen einer Kardiomyopathie und akuter Ischämie, sowohl im Tiermodell als auch beim Patienten. Neuartige Mappingtechnologien und Tiermodelle können helfen, die Mechanismen zu verstehen, die Therapie von Herzrhythmusstörungen zu verbessern und Therapieverfahren weiterzuentwickeln.<br>Sudden cardiac death is one of the leading causes of death in Europe, and the leading cause of all natural deaths in the USA. The primary aim of experimental and clinical research is the "prediction and prevention" of lethal ventricular arrhythmias. The focus of this thesis is on animal studies investigating the mechanisms of arrhythmias. Using a novel multichannel electrical cardiac mapping technique we were able to demonstrate that whatever generates fibrillation activations it locates at a small region in the LV apex. This research will widen our understanding of defibrillation and causes of lethal ventricular arrhythmias, but is still only a piece of the puzzle called sudden cardiac death. New initiated or planed project are focusing on arrhythmias in patients and animals with heart failure or acute ischemia. Novel mapping techniques and animal models might further widen our understanding of the mechanisms and might help to develop and improve therapeutic options.
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Goulart, Jair Trapé 1987. "Vulnerabilidade de miócitos cardíacos a campos elétricos de alta intensidade = influência da estimulação beta-adrenérgica = The lethal effect of high-intensity electric fields on cardiac myocytes: influence of the beta-adrenergic pathway." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259400.
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Orientadores: José Wilson Magalhães Bassani, Rosana Almada Bassani<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-20T23:57:01Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012<br>Resumo: A aplicação de campos elétricos de alta intensidade (CEAI) no coração é realizada frequentemente durante tentativas de reversão da fibrilação, e para gerar sincronismo cardíaco com o uso de marca-passos. Entretanto, este procedimento rotineiro pode causar danos ao miocárdio. O objetivo deste trabalho foi investigar se a estimulação ?-adrenérgica afeta a vulnerabilidade de miócitos ventriculares ao CEAI, uma vez que, durante a fibrilação ventricular, há aumento reflexo do tônus simpático, em virtude da consequente hipotensão arterial, e a administração de catecolaminas é um procedimento comum neste tipo de emergência. Miócitos foram isolados do ventrículo esquerdo de ratos Wistar adultos por digestão enzimática. As células foram perfundidas com solução de Tyrode a 23 °C e estimuladas a 0,5 Hz. Aplicou-se CEAI em intensidades crescentes até que fosse induzida uma lesão letal na célula. A probabilidade de morte celular foi determinada em função da amplitude do CEIA e da máxima variação estimada do potencial de membrana (?Vmax) por análise de sobrevivência (curva de letalidade). Destas curvas, obteve-se o parâmetro EL50 (valor de CEAI ou ?Vmax com probabilidade de letalidade de 0,5). A estimulação ?-adrenérgica, pela perfusão com 10 nM de isoproterenol (ISO), foi realizada na ausência e presença de 150 nM de metoprolol (MET, bloqueador de adrenoceptores ?1), 10 ?M de H-89 (inibidor de PKA) e 500 nM de BIS I (inibidor de PKC), bem como após protocolo para minimizar o aumento de mobilização celular de Ca2+. As curvas foram comparadas por teste de Mantel-Cox. O tratamento com ISO promoveu o deslocamento da curva para a direita (p < 0,01) e EL50 aumentou de 85 para 100 V/cm. MET e H-89 aboliram o efeito protetor do ISO, e, quando perfundidos na ausência de ISO, não tiveram quaisquer efeitos sobre a indução de letalidade por CEAI. A redução da mobilização de Ca2+ e o tratamento com BIS I não alteraram as curvas de letalidade, na presença ou ausência de ISO, mas provocaram significante aumento no tempo de recuperação das células após um choque não letal. As curvas em função de ?Vmax foram similares àquelas em função da intensidade do campo. Os resultados mostram que a estimulação ?-adrenérgica é capaz de proteger os miócitos dos efeitos deletérios do CEAI, permitindo que a célula suporte maiores ?Vmax. A proteção parece ser mediada por adrenoceptores ?1 e PKA, e possivelmente envolve ativação de mecanismos de reparo. Estas vias de proteção podem ser futuramente exploradas para atenuar os danos miocárdicos causados pela desfibrilação/cardioversão<br>Abstract: The myocardium is exposed to high-intensity electric fields (HIEF) during cardiac electric defibrillation, which may reverse life-threatening arrhythmias, but also cause cell damage. Impairment of cardiac pumping during ventricular fibrillation is usually associated with high sympathetic tone, and catecholamine infusion is a common procedure for the emergencial treatment of this arrhyhmia. The present study was carried out to investigate whether adrenergic stimulation affects the vulnerability of ventricular myocytes to the lethal effect of HIEF. Left ventricular myocytes were isolated from adult Wistar rat hearts by collagenase digestion. Under perfusion with Tyrode's solution at 23 ºC, cyclic contractile activity was evoked by stimulation at 0.5 Hz. A HIEF pulse was then applied, after which cells were allowed to rest and recover from the shock. Afterward, the protocol was repeated increasing HIEF amplitude until cell death ensued. The probability of cell death as a function of the field intensity or the estimated maximum change in membrane potential, ?Vmax (lethality curve) was determined by survival analysis. The protocol was carried out during exposure to 10 nM isoproternol (ISO), in the absence and presence of the ?1-adrenoceptor blocker metoprolol (MET, 150 nM), the PKA inhibitor H-89 (10 ?M), the PKC inhibitor BIS I (500 nM), or after a protocol designed to attenuate the increase in cell Ca2+ mobilization by ISO. Lethality curves were compared with the Mantel-Cox test. Exposure to ISO produced a marked rightward shift of the lethality curves (p< 0.01), and the field intensity associated with the cell death probability of 0.5 (EL50) was increased from 85 to 100 V/cm. Treatment with MET or H-89 alone did not significantly affect the curves, but completely abolished ISO protective effect. Decreasing Ca2+ mobilization and BIS I treatment did not produce significant effects on the lethality curves, either in the absence or presence of ISO, but they increased the time spent to cell recovery after a non-lethal shock. Similar results were obtained for the lethality curve as a function of ?Vmax. Therefore, ?-adrenergic stimulation confers protection to ventricular myocytes from the lethal effects of HIEF, even though cells apparently experience higher variations of ?Vmax, which should lead to extensive electroporation. This effect, which seems to be mediated by ?1-adrenoceptors and dependent on PKA activation, possibly involving recruitment of membrane repair mechanisms. This protective effect may be further explored as a means to attenuate HIEF deleterious effects on cardiac function that frequently result from electric defibrillation/cardioversion<br>Mestrado<br>Engenharia Biomedica<br>Mestre em Engenharia Elétrica
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Michael, Kevin A. "An analysis of defibrillation and cardiac resynchronization therapy strategies in patients with failing systemic right ventricles." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/2827.
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Includes bibliographical references (leaves 52-56).<br>The expanding application of cardiac resynchronization (CRT) and implantable cardioverter-defibrillator therapy (lCD) to include patients with congenital heart disease requires careful evaluation of selection criteria and unconventional adaptive strategies to ensure clinical efficacy. A single centre prospective analysis of adults post atrial redirection surgery (Mustard operation) for dextro-transposition of the great arteries (d-TGA) presenting with systemic right ventricular (sRV) dysfunction and at risk of sudden cardiac death (SCD). All patients ( mean age 25 years, range 18-35) with varying functional disability{New York Heart Association (NYHA) II-III} receiving ICDs ± concomitant CRT were evaluated. Total follow-up period was 24 months. A patient individualized approach was used for device implantation. Endocardial, epicardial and transthoracic defibrillation strategies were examined in 5 consecutive cases. A hybridized form of CRT was employed in two patients. Only one patient demonstrated response to therapy while the other deteriorated during biventricular pacing (BVP). This prompted a novel approach to CRT using noncontact mapping (NCM) and acute intra-arterial blood pressure response to guide endocardialsRV lead placement in a single patient. The ejection fraction increased from 23 -33% within 1week post procedure and clinical improvement was sustained after 6-months follow-up. Application of CRT II CD therapy to patients with sRV dysfunction requires individualized and adaptive strategies to overcome anatomical constraints. This study represents a chronological and evolutionary account of these measures.
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Wang, Yves Terence. "Effects of Interventions Following Myocardial Infarction: Defibrillation-Induced Electroporation and Reverse Remodeling Following Surgical Ventricular Reconstruction." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1327695637.
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Wang, Yanqun. "Analysis of defibrillation efficacy and investigation of impedance cardiography with finite element models incorporating anisotropic myocardium /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8104.
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Moore, Michael John. "A study of the effectiveness of public access defibrillation in urban and rural populations in Northern Ireland." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479309.
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Brügmann, Tobias [Verfasser]. "Optogenetics in striated muscle: defibrillation of the heart and direct stimulation of skeletal muscles with light / Tobias Brügmann." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1201727839/34.
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GRENIER, DE GAYARDON DE FENOYL FRANCE. "Defibrillation ventriculaire precoce : interet des defibrillateurs semi-automatiques ; a propos de 70 cas d'utilisation en milieu extra-hospitalier." Lyon 1, 1992. http://www.theses.fr/1992LYO1M092.
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Gu, Yiping. "ENTRAINMENT OF ELECTRICAL ACTIVATION BY SPATIO-TEMPORAL DISTRIBUTED PACING DURING VENTRICULAR FIBRILLATION." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/193.
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Spatio-temporal variation in action intervals during ventricular fibrillation (VF) suggestthat the excitable gap may also be distributed spatio-temporally. The observation leadus to hypothesize that distributed pacing can be used to modify and entrain electricalactivation during VF. We tested this hypothesis using simulated VF and animal studies.
We simulated VF in a 400 by 400 cell matrix. Simulation results showed that activationpattern could be entrained using spatially distributed stimulation. Up to a certain limit,increasing stimulus strength and density led to improved entrainment. Best entrainmentwas obtained by pacing at a cycle length similar to the intrinsic cycle length.
In order to verify whether activation could be entrained experimentally, eight opticallyisolated biphasic TTL addressable stimulators were fabricated. Distributed stimulationwas tested during electrically induced VF in two canines and two swine. Resultsshowed that electrical activation could be entrained in both species. Similar to that insimulation, better entrainment was obtained with denser pacing distribution and atpacing cycle length similar to the intrinsic cycle length. As expected, entrainment wasaffected by tissue thickness. Our results show that spatio-temporally distributed pacingstrength stimuli can be used to modify activation patterns during VF.
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Sekimoto, Miho. "The impact of basic emergency medical technician with defibrillation system on survival after out-of-hospital cardiac arrest in Japan." Kyoto University, 2003. http://hdl.handle.net/2433/148704.
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Golshayan, Maryam. "A study of internal defibrillation efficacy using finite element analysis: a 3D isotropic finite element model of the myocardium electric fields." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18790.
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Ventricle fibrillation (VF) is a condition in which the heart's lower chambers show an unsynchronized and chaotic motion which prevents the heart from pumping blood and oxygen to the body. VF is considered a sudden cardiac arrest and it is responsible for 300,000 sudden deaths in the USA yearly. The most effective way of reversing this life threatening condition is to apply an electrical shock directly to the heart using an Implantable Cardioverter-Defibrillator (ICD). The main issue in using ICDs is the placement of the defibrillating electrodes so that the current can be optimally channeled through the cardiac muscle, particularly in the left ventricular myocardium. According to the critical mass hypothesis, defibrillation will be successful when 75% of the myocardium tissue is halted by the defibrillation shock. The defibrillation threshold (DFT) or the minimum effective voltage required for successful results is suggested to be related to the myocardial voltage gradient (VG) distribution, but it has not been quantified. Moreover, the goal is to keep the DFT as low as possible to try to maximize the success of defibrillation, minimize the chance of myocardium damage and cardiac arrhythmias caused by high-intensity shocks, and also potentially reduce the battery size and as well as prolong the device's useful lifespan. Various numerical techniques have been used to model the heart to solve the governing equations required to obtain the myocardium VG distribution during electrical defibrillation. The Finite Element Method (FEM) has been of particular interest since it can handle the irregular domains, material inhomogeneities, and complex boundary conditions of problems in bioelectricity. In this thesis, a finite element model of the heart tissue is constructed in order to study and optimize the defibrillation mechanism. The modelling process starts with a surface reconstruction based on radial basis function interpolation to generate the triangular surface me<br>La fibrillation ventriculaire (FV) est un état dans lequel la cavité inférieure du coeur montre une motion asynchrone et chaotique, empêchant le coeur de pomper le sang et l'oxygène au corps. La FV est considérée comme un arrêt cardiaque soudain, responsable de la mort subite de 300,000 personnes chaque année aux Etats-Unis. Afin d'inverser cette condition mortelle, le recours le plus efficace est la délivrance d'un choc électrique directement au niveau du coeur à l'aide d'un Défibrillateur Cardioverteur Implantable (DCI). Le principal problème de l'utilisation des DCIs est le placement des électrodes défibrillateurs pour permettre au courant d'être conduit optimalment à travers du muscle cardiaque, en particulier, le myocarde ventriculaire gauche. Selon l'hypothèse de la masse critique, la défibrillation sera réussi quand 75% du tissu de myocarde est inactivé par le choc de défibrillation. Le seuil de défibrillation ou la tension efficace minimale exigée pour donner des résultats réussis est suggéré d'être liés à la distribution du gradient de la tension myocardique, toutefois, il n'a pas été mesurée. En outre, le but est de maintenir le seuil de défibrillation aussi bas que possible pour essayer de maximiser le succès de la défibrillation, réduire au minimum le risque des dommages de myocarde et des arythmies cardiaques provoqués par des chocs à haute intensité, et aussi permettre de réduire la taille de la batterie ainsi que prolonger la durée de la vie utile du dispositif. De diverses techniques numériques ont été utilisées pour modeler le coeur afin de résoudre les équations régissant requises pour obtenir la distribution de gradient de la tension myocardique pendant la défibrillation. La méthode des éléments finis (FEM) a été d'intérêt particulier car elle peut gérer les domaines irréguliers, les hétérogénéité de matériel, et les conditions aux limites complexe de problèmes dans la bioélec
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Dahan, Benjamin. "Mort subite de l'adulte : stratégie de déploiement des défibrillateurs automatisés externes." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB092/document.
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L’arrêt cardiaque extra-hospitalier (ACEH) est un problème de santé publique majeur. La réanimation cardio-pulmonaire (RCP) précoce ainsi que la défibrillation par les témoins sont associées à une augmentation du taux de survie. Cependant, malgré d’importants efforts ces dernières années, les taux de survie restent faibles dans la plupart des pays. Ce travail avait pour objectif d’identifier des facteurs ayant un impact sur la défibrillation publique, la RCP précoce et les connaissances du public sur la défibrillation. Nous avons testé différentes stratégies de déploiement des défibrillateurs automatisés externes (DAE). Nous avons également analysé l’effet du niveau socio-économique des quartiers sur la RCP par les témoins. Enfin, nous avons cherché à évaluer les connaissances du public concernant la localisation et les conditions d’utilisation du DAE le plus proche dans des lieux publics très fréquentés. Tous les ACEH survenus à Paris entre 2000 et 2010 ont été enregistrés dans un registre et géocodés. Nous avons comparé une stratégie basée sur les recommandations de placement d’un DAE dans les lieux où plus d’un ACEH survenait tous les cinq ans à deux nouvelles stratégies : une stratégie de maillage régulier du territoire avec des DAE placés à distances régulières et une stratégie de placement dans différents types de lieux publics. Le nombre de DAE nécessaires ainsi que la distance médiane entre les ACEH et le DAE le plus proche étaient calculés pour chaque stratégie. Nous avons également recherché l’association entre le niveau socio-économique des quartiers sur le fait de bénéficier d’une RCP. Enfin, nous avons réalisé une enquête dans des lieux publics très fréquentés (gare, centres commerciaux, jardin public) auprès de toutes les personnes situées dans un rayon de 100 mètres autour d’un DAE pour analyser leur connaissance de la localisation du DAE et leur capacité à l’utiliser. Parmi 4176 ACEH, 1372 (33%) sont survenus dans des lieux publics. La stratégie basée sur les recommandations aurait conduit au placement de 170 DAE avec une distance aux ACEH de 416 (180-614) mètres et une augmentation continue du nombre de DAE. Avec la stratégie de maillage régulier du territoire, le nombre de DAE et la distance aux ACEH auraient changé selon la taille du maillage avec un nombre optimal de DAE évalué entre 200 et 400. Avec la stratégie de placement dans différents types de lieux publics, la distance médiane entre les ACEH et les DAE aurait été de 324 mètres pour les bureaux de poste (195), 239 mètres pour les stations de métro (302), 137 mètres pour les stations Velib’ (957) et 142 mètres pour les pharmacies (1466). Parmi les 4009 ACEH géocodables enregistrés, 777 (19,4%) ont bénéficié d’une RCP par un témoin. Ceux qui en ont bénéficié étaient plus fréquemment dans un lieu public, en présence d’un témoin et dans un quartier de statut socio-économique (SSE) non défavorisé. Dans une analyse multiniveaux la RCP par les témoins était significativement moins fréquente dans les quartiers de SSE défavorisé que dans les quartiers d’autres SSE (OR 0,85 ; 95% IC 0,72-0,99). Notre enquête a été menée auprès de 301 participants. Environ la moitié des participants (49%) avaient bénéficié d’une formation aux premiers secours, dont 70% après 2007 et 37% qui avaient suivi une initiation d’une heure. Le logo universel des DAE était reconnu par 37% des participants et 64% pouvaient reconnaître un DAE en photo. La localisation du DAE le plus proche était connue par 16% des participants avec un impact positif des formations après 2007 et de la reconnaissance du logo ou des photos (p<0,0001). Une majorité de participants (66%) savaient qu’ils avaient le droit d’utiliser un DAE et 59% savaient dans quelles circonstances l’utiliser. Seulement 25% des participants déclaraient savoir comment utiliser un DAE. Notre travail présente une approche originale pour optimiser les stratégies de déploiement des DAE. (...)<br>Out-of-hospital cardiac arrest (OHCA) is a major public health concern. Early bystander cardiopulmonary resuscitation (CPR) and defibrillation are associated with higher survival rates for OHCA victims. Unfortunately, despite major efforts over the past decade, survival rates remain low in many communities. This work sought to highlight factors affecting public defibrillation, early CPR and public knowledge on defibrillation. We assessed different strategies for Automated External Defibrillators (AEDs) deployment. We also aimed to focus effect of neighborhood socio-economic status on bystander CPR. Finally, we sought to analyze public awareness of the AED nearest location and knowledge of AED use. All OHCAs attended by EMS in Paris between 2000 and 2010 were prospectively recorded and geocoded. We compared a guidelines-based strategy of placing an AED in locations where more than one OHCA had occurred within the past five years to two novel strategies: a grid-based strategy with a regular distance between AEDs and a landmark-based strategy. The expected number of AEDs necessary and their median (IQR) distance to the nearest OHCA were assessed for each strategy. We also evaluated the relationship between neighbourhood SES characteristics and the fact of receiving bystander CPR. Then, we performed a survey in three kinds of places (train station, city mall and public park) of all individuals within 100 meters from an AED to analyze their knowledge of the closest AED location and their confidence to use it. Of 4,176 OHCAs, 1,372 (33%) occurred in public settings. The guidelines-based strategy would result in the placement of 170 AEDs, with a distance to OHCA of 416 (180-614) meters and a continuous increase in the number of AEDS. In grid-based strategy, the number of AEDs and their distance to the closest OHCA would change with the grid size, with a number of AEDs between 200 and 400 seeming optimal. In landmark-based strategy, median distances between OHCAs and AEDs would be 324 meters if placed at post offices (n=195), 239 at subway stations (n=302), 137 at bike-sharing stations (n=957), and 142 at pharmacies (n=1466). Of the 4,009 OHCA with mappable addresses recorded, 777 (19.4%) received bystander CPR. Those receiving it were more likely to be in public locations, have had a witness to their OHCA, and to have collapsed in a non-low SES neighbourhood. In a multilevel analyses, bystander CPR provision was significantly less frequent in low than in higher SES neighbourhoods (OR 0.85; 95% confidence interval [CI] 0.72-0.99). A total of 301 people responded to the survey. About half respondents (49%) had a Basic Life Support training experience with 70 % of them trained after 2007 and 37% who attempted a one hour training initiation. The universal AED sign was recognized by 37% of all respondents and 64% could recognize an AED on a picture. The closest AED location was known by 16% of the respondents with a positive impact of training after 2007 and knowledge of AED sign and picture (p<0.0001). A majority of respondents (66%), considered they had the right to use an AED and 59% knew in which circumstances it is necessary to use it. Only 25% of the respondents declared to know how to use an AED. Our work presents an original evidence-based approach to strategies of AED deployment to optimize their number and location. This rational approach can estimate the optimal number of AEDs for any city. In Paris, OHCA victims were less likely to receive bystander CPR in low SES neighbourhoods. These first European data are consistent with observations in North America and Asia. Our survey conducted in places known to be at risk of OHCA highlights the need for a better AED visibility in public places and the need to improve public knowledge and confidence in the use of AED. (...)
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Zoccoler, Marcelo 1987. "Estudo espaço-temporal da concentração de cálcio citosólico de miócitos cardíacos isolados expostos a campos elétricos de alta intensidade." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259736.
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Orientador: Pedro Xavier de Oliveira<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-25T18:17:39Z (GMT). No. of bitstreams: 1
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Previous issue date: 2014<br>Resumo: A fibrilação ventricular é uma quadro extremamente grave de ameaça imediata à vida e a única terapia efetiva para sua reversão é a desfibrilação, que consiste na aplicação de campos elétricos (E) de alta intensidade sobre o coração. Este procedimento é capaz de restabelecer o sincronismo do coração, mas ele pode causar lesão em miócitos. A lesão depende da direção de E e é atribuída à eletroporação - formação de poros hidrofílicos na membrana celular - que leva a um aumento expressivo da concentração de íons Ca2+ livres no citosol ([Ca2+]i), resultante de influxo de Ca2+ extracelular pelos poros. Neste trabalho, produzimos um sistema de microfluorimetria capaz de registrar imagens de fluorescência de miócitos cardíacos isolados e estudamos a lesão causada por E de alta intensidade por meio do aumento da fluorescência associada a [Ca2+]i em miócitos orientados longitudinalmente e transversalmente a E. As células foram carregadas com o indicador de fluorescência Fluo-3, estimuladas a 0,5Hz por E de baixa intensidade antes da aplicação de um pulso de E de alta intensidade sub-letal. As imagens de fluorescência foram capturadas por uma câmera EMCCD e processadas por um software específico desenvolvido neste trabalho. O software utilizou dois métodos de análise: média de fluorescência normalizada e razão de uma área que mostrou aumento significativo de fluorescência dividida pela área total da célula. Análise de regiões de interesse (ROIs) voltadas para o ânodo e o cátodo produziu resultados em concordância com a literatura, com maior lesão (inferida por aumento de [Ca2+]i) no lado do ânodo (P<0,05 nos dois os métodos). A comparação entre os grupos longitudinal e transversal apresentou diferença estatística relevante no método da razão de áreas, o que não ocorreu pelo método de média de fluorescência. Imaginamos que a utilização de uma técnica mais direta para medir eletroporação possa solidificar esta correlação entre orientação e lesão. A compreensão dos mecanismos responsáveis pela severidade das lesões é importante para desenvolver terapias mais seguras<br>Abstract: Ventricular fibrillation is an extremely dangerous immediate life-threatening condition and the only effective therapy to its reversion is defibrillation, which consists in applying high intensity electric fields (E) on the heart. Such procedure is capable of reestablishing heart synchronism, but it may also cause lesion in myocytes. Lesion is associated to E direction and is assigned to electroporation - generation of hydrophilic pores across the membrane caused by high intensity E - which results in an expressive increase in cytosol free Ca2+ concentration ([Ca2+]i), a consequence from extracellular Ca2+ influx through the pores. In this work, we produced a microfluorimetry system capable of recording isolated cardiomyocytes fluorescence images and studied lesion caused by high intensity E by the means of the rise in [Ca2+]i associated fluorescence in myocytes oriented longitudinally and transversally to E. Cells were loaded with fluorescent dye Fluo-3, paced at 0,5Hz with low intensity E before setting one sub-lethal high intensity E pulse. Fluorescence images were recorded by an EMCCD camera and processed by a specific software developed in this work. The software used two analysis methods: normalized fluorescence average and a ratio of an area showing most significant fluorescence increase divided by cell total area. Regions of interest (ROIs) analysis facing the anode and the cathode has produced results in accordance with literature, presenting higher lesion (inferred by [Ca2+]i increase) at anode side (P<0,05 in both methods). Comparison between longitudinal and transversal groups has presented relevant statistic difference when the ratio of areas method was employed, which has no happened when employing the fluorescence average method. We imagine that using a straight-foward technique for assessing electroporation may solidify this correlation between orientation and lesion. The understanding of the mechanisms responsible for lesion severity is important to develop safer therapies<br>Mestrado<br>Engenharia Biomedica<br>Mestre em Engenharia Elétrica
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Varma, Pryamvada Yasomatee. "Effect of combination I¦K¦1 and I¦K¦r blockade on defibrillation and cardiac refractoriness in the isolated Langendorff rabbit heart model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ54171.pdf.
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Gercken, Martina [Verfasser], Daniel Peter [Verfasser] Franzen, and Wilhelm [Verfasser] Krone. "Klinische Studie zur elektrischen Therapie von Vorhofflimmern mittels R-Zacken gesteuerter Cardioversion versus Defibrillation (VCD-Studie) / Martina Gercken, Daniel Peter Franzen, Wilhelm Krone." Köln : Deutsche Zentralbibliothek für Medizin, 2019. http://d-nb.info/1196880506/34.
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Strutz, Joanna [Verfasser], Dietrich [Akademischer Betreuer] Kettler, Jean-François [Akademischer Betreuer] Chenot, and Christina [Akademischer Betreuer] Unterberg-Buchwald. "Strukturelle Erwägungen zur Implementierung der automatisierten externen Defibrillation im Landkreis Göttingen / Joanna Strutz. Gutachter: Jean-François Chenot ; Christina Unterberg-Buchwald. Betreuer: Dietrich Kettler." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1042530432/34.
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Gercken, Martina [Verfasser], Daniel Peter Verfasser] Franzen, and Wilhelm [Verfasser] [Krone. "Klinische Studie zur elektrischen Therapie von Vorhofflimmern mittels R-Zacken gesteuerter Cardioversion versus Defibrillation (VCD-Studie) / Martina Gercken, Daniel Peter Franzen, Wilhelm Krone." Köln : Deutsche Zentralbibliothek für Medizin, 2019. http://d-nb.info/1196880506/34.
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Abu, Nahleh Kais [Verfasser], Torsten [Akademischer Betreuer] Birkholz, Torsten [Gutachter] Birkholz, and Jürgen [Gutachter] Schüttler. "Untersuchung des Nutzens und der unmittelbaren Auswirkung von Schrittmacherimpulsen nach Defibrillation bei Kammerflimmern / Kais Abu Nahleh ; Gutachter: Torsten Birkholz, Jürgen Schüttler ; Betreuer: Torsten Birkholz." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1185171231/34.
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Hebert, Robin Lewis. "Initiation of In-hospital CPR: An Examination of Nursing Behaviour Within their Scope of Practice." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35804.
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Cardiopulmonary resuscitation (CPR) and defibrillation are the interventions performed by health care professionals in order to preserve the life of a patient suffering cardiac arrest. These tasks are important to the role of nurses because they are the most common first responders to in-hospital cardiac arrest scenarios. The early initiation of CPR and defibrillation is essential in increasing the likelihood of a patient surviving cardiac arrest. Despite possessing the knowledge, skills, training, and professional obligation to deploy CPR and defibrillation independently, nurses may hesitate to perform the appropriate actions in a timely manner. This topic has been studied previously; however, there have been no studies directly examining this issue in the Ontario context. This thesis explored the factors that influence the behaviour of nurses in the first responder role by employing a mixed-methods research design. The quantitative portion of the study consisted of a series of scales on an online survey that examined teamwork factors and nurses’ experience with CPR events. The qualitative part of the study consisted of open-ended questions on the survey as well as individual interviews with nurses to understand the barriers and enablers to the role of nurses in the enactment of basic life support (BLS). The qualitative data were analyzed with a modified grounded theory approach. The qualitative data analysis followed the guidelines developed by Charmaz (2006) and employed the conceptual framework on optimizing scopes of practice developed by the Canadian Academy of Health Sciences (2014) to extrapolate findings on the influence of nurses’ scope of practice on their behaviour. This study revealed a number of contextual factors in Ontario influencing nurses’ deployment of CPR and defibrillation including variations in hospital unit types, geography, workload, the availability and quality of technology, legislation and regulation, accountability, as well as economic constraints.
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Finzi, A. A. "AMPLITUDE SPECTRUM AREA AS A PREDICTOR OF SUCCESSFUL DEFIBRILLATION: THRESHOLD VALUES ANALYSIS IN A LARGE DATABASE OF OUT-OF-HOSPITAL CARDIAC ARREST TREATED BY DC-SHOCK." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/217617.
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La scelta del momento di procedure alla defibrillazione (DF) di un paziente in fibrillazione ventricolare (FV) comporta l’interruzione del massaggio cardiaco e, in caso di inefficacia, il rischio di aggiungere un ulteriore danno miocardico. Perciò è assai importante individuare un indicatore affidabile della probabilità di successo utilizzabile in tempo reale. In questo studio è stata valutata la capacità della Amplitude Spectrum Area (AMSA) nel predire l’esito della defibrillazione in una vasta popolazione di pazienti con arresto cardiaco extraospedaliero.
Sono stati acquisiti gli elettrocardiogrammi (ECG) dalla memoria dei defibrillatori esterni utilizzati dagli operatori del 118 di 7 province lombarde nel periodo 2008-2009 in 8419 eventi di arresto cardiaco. Di essi sono stati analizzati i 1055 nei quali è stata effettuata una DF. L’AMSA è stato calcolato analizzando una finestra di 2 sec di ECG che terminava 0.5 sec prima della DF utilizzando una trasformata di Fourier per l’ampiezza e la frequenza. Il successo della DF è stato definito come la presenza di un ritmo stabile a frequenza di 40 bpm 60 sec dopo la DF. Sono stati individuati i valori soglia dell’AMSA per discriminare il risultato della DF, sono state calcolate sensibilità, specificità, predittività positiva e negativa ed è stata misurata l’area sotto la curva ROC.
Sono stati inclusi 2442 eventi di DF, fra cui 1055 prime DF e 1387 successive. Sono risultate efficaci rispettivamente il 26% di tutte le DF, il 27% delle prime e il 25.2% delle successive. L’AMSA è risultato significativamente maggiore prima delle DF efficaci rispetto a quello ottenuto prima delle DF inefficaci (13.8 vs 6.9 mV-Hz, 13.9 vs. 6.8 mV-Hz, e 13.7 vs. 7 mV-Hz rispettivamente per tutte le DF ,le prime e le successive). L’intersezione delle curve di sensibilità, specifictà e predittività ha identificato un valore soglia di AMSA di 9.5 mV-Hz capace di predire il risultato della DF con un valore bilanciato dell’80% per tutte, le prime e le successive DF. Valori di AMSA > 27 mV-Hz hanno correttamente previsto un successo del 100%, mentre un valore di 8,5 mV-Hz ha previsto l’insuccesso con predittività negativa > 95% ed un valore di 4 mV-Hz indicava il 100% di probabilità di insuccesso. L’area sotto la curva ROC è risultata 0.872, 0.869 e 0.875 rispettivamente per tutte le DF, le prime e le successive.
In questa vasta popolazione di pazienti con arresto cardiaco un algoritmo AMSA è stato capace di predire l’esito della DF con notevole accuratezza. Una soglia specifica di AMSA che identifichi le probabilità di successo o insuccesso è ottenibile anche durante massaggio cardiaco. Pertanto la decisione di attuare la DF basata sull’AMSA può essere utile per migliorare l’esito della rianimazione cardiopolmonare.<br>Timing of defibrillation (DF) to interrupt ventricular fibrillation (VF) is of utmost importance as it implies interruption of chest compression and,in case of failure, the risk of adding further damage to the already critical myocardial condition. In such scenario, a real-time indicator of the probability of success is needed . This study was aimed to the capability of “Amplitude Spectrum Area” (AMSA) to predict DF outcome in a large database of out-of-hospital cardiac arrest. Electrocardiographic (ECG) data recorded by automated external defibrillators were obtained from 8.419 cardiac arrest events occurring in 7 provinces in Lombardia Region, Italy, between 2008 and 2009. Among these events, only VF/VT cardiac arrests receiving DFs were selected (n=1055). A 2 sec ECG window ending at 0.5 sec before DF was analyzed and AMSA calculated, after fast Fourier transformation. DF was defined as successful in the presence of spontaneous rhythm 40 bpm starting within 60 secs from the DF. Threshold values of AMSA able to discriminate DF outcome were individuated and sensitivity, specificity, accuracy, positive and negative predictive values (PPV, NPV) were calculated. The area under the receiver operating characteristic (ROC) curve was measured. A total of 2.442 quality DF events, including 1055 first attempts and 1.387 subsequent ones were included in the analyses. DF success rate was of 26%, 27%, and 25.2% for all, first, and subsequent DFs, respectively. AMSA was significantly greater prior to successful DFs, compared to that preceding unsuccessful ones (13.8 vs. 6.9 mV-Hz, and 13.9 vs. 6.8 mV-Hz, and 13.7 vs. 7 mV-Hz, for all, first, and subsequent DFs respectively). Intersection of sensitivity, specificity and accuracy curves identified a threshold value of AMSA of approximately 9.5 mV-Hz, able to predict DF outcome, with a balanced sensitivity, specificity and accuracy of 80%, for all, first, and subsequent DFs . Moreover, intersection of PPV and accuracy curves identified a threshold value of AMSA of approximately 15 mV-Hz able to predict a successful DF with a PPV and accuracy of 80%, for all, first, and subsequent DF attempts. AMSA values greater than 27 mV-Hz correctly predicted the success of DF with a PPV value of 100%. AMSA below 8 mV-Hz correctly predicted the DF failure with a NPV of > 95%, for all, first, and subsequent DFs. Further decreases in AMSA values below 4 mV-Hz achieved a NPV of 100%. Area under ROC curves was 0.872, 0.869, and 0.875 for all, first, and subsequent DFs, respectively
In this large patient population, an AMSA algorithm was capable to predict DF outcome with high accuracy. A specific AMSA threshold in order to predict DF outcome, i.e. success or failure, may be identified during CPR. An AMSA-based DF decision therefore would be an useful approach to guide the best CPR intervention.
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BLEUEZ, NATHALIE. "La defibrillation ventriculaire precoce en milieu extra-hospitalier : interet des defibrillateurs semi-automatiques ; a propos de 140 cas ; etude menee pour le samu regional de lyon." Lille 2, 1993. http://www.theses.fr/1993LIL2M199.
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Fonseca, Alexandra Valenzuela Santelices da. "Estimulação multidirecional de celulas cardiacas : instrumentação e experimentação." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259396.
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Orientadores: Jose Wilson Magalhaes Bassani, Rosana Almada Bassani<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação<br>Made available in DSpace on 2018-08-15T01:38:31Z (GMT). No. of bitstreams: 1
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Previous issue date: 2009<br>Resumo: O procedimento mais efetivo para reverter arritmias cardíacas consiste na aplicação de choques elétricos de alta intensidade, como e o caso da desfibrilação. Estimulação com campos elétricos (E) elevados, entretanto, exerce efeitos deletérios sobre o músculo cardíaco, podendo causar disfunções elétrica e contrátil e até a morte celular. Privilegiar a estimulação na direção longitudinal, para qual o limiar de excitação das células cardíacas e menor, seria uma forma de se reduzir a amplitude do estimulo sem perder a efetividade da estimulação. Para isto, foi desenvolvido e testado, em miócitos ventriculares orientados de maneira aleatória, um sistema de estimulação multidirecional automática que permite o chaveamento controlado de estímulos sequênciais para três diferentes pares de eletrodos (cada um correspondendo a uma direção) em um intervalo de tempo inferior a duração do potencial de ação (período em que a célula se encontra eletricamente refrataria). A estimulação multidirecional com uma intensidade de E 20% acima do limiar estimulatório (1,2× ETM) dobrou o recrutamento (excitação) de células (80 vs. 40% com estimulação unidirecional, p<0,001). Adicionalmente, o recrutamento com a estimulação multidirecional automática foi maior (p< 0,001) do que a soma dos recrutamentos obtidos com a estimulação em cada direção individualmente (sem intersecção), o que sugere que a estimulação sublimiar durante o procedimento automático pode aumentar a excitabilidade celular. Foi observado também que, para uma dada amplitude do estimulo, o uso da forma de onda bipolar (para a qual o valor de ETM foi menor que para pulsos monopolares: 3,2 ± 0,1 vs. 3,9 ± 0,1 V/cm; p< 0,001) promoveu um recrutamento maior do que com o pulso monopolar (recrutamento de 50% das células foi obtido com 2,97 ± 0,04 e 4,18 ± 0,05 V/cm para pulsos bipolares e monopolares, respectivamente; p< 0,05). A combinação da estimulação multidirecional automática com o uso da forma de onda bipolar permitiu, portanto, uma redução de cerca de 50% no valor do E absoluto (3,8 vs. 7,8 V/cm com estimulação unidirecional e pulso monopolar) para um recrutamento de ~80% das células. A aplicação destes procedimentos na
estimulação cardíaca (marcapasso e desfibrilação) pode otimizar o processo, levando a uma melhor eficiência e uma menor incidência de lesão.<br>Abstract: The most effective procedure to revert cardiac arrhythmias consists in the application of high intensity electric discharge, such as in cardiac defibrillation. Nevertheless, stimulation using high electric fields (E) may cause injury to the cardiac muscle, generating electric and contractile dysfunctions and even cell death. A possible way to reduce the stimulus intensity while maintaining the stimulation effectiveness would be stimulate cardiac cells with E applied parallel to the cell major axis, in which case the stimulation threshold is lower. To test this possibility, a multidirectional stimulation system was developed and tested on randomly-oriented rat ventricular myocytes. The system allows the controlled switching of sequential stimuli delivered to three different pairs of electrodes (each one corresponding to one direction), in a period shorter than the action potential duration (when cell is electrically refractory). The multidirectional stimulation with E intensity 20% above the stimulation threshold (1.2× ETM) doubled the percentage of recruited (excited) cells (~80 vs. ~40 % with unidirectional stimulation, p<0.001). Additionally, recruitment with automatic multidirectional stimulation was greater (p< 0.001) than the sum of recruitments obtained from stimulation of each direction individually (without intersection), which is suggestive that subthreshold stimulation during the automatic procedure might enhance cell excitability. Moreover, it was observed that for a given absolute stimulus amplitude, the use of biphasic waveforms (for which ETM was lower than for monophasic pulses: 3.2 ± 0.1 vs. 3.9 ± 0.1 V/cm; p< 0.001) promoted higher recruitment than monophasic stimuli (50% recruitment was attained with 2.97 ± 0.04 and 4.18 ± 0.05 V/cm with biphasic and monophasic pulses, respectively; p< 0.05). Thus, the association of automatic multidirectional stimulation and biphasic waveform enabled a 50% reduction of the absolute E value (3.8 vs. 7.8 V/cm with unidirectional stimulation and monopolar pulse) to evoke excitation in ~80% of the cells. The application of these procedures to cardiac stimulation (pacemaker and defibrillation) might optimize the process, leading to greater efficiency and lower injury incidence.<br>Mestrado<br>Engenharia Biomedica<br>Mestre em Engenharia Elétrica
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Marijon, Eloi. "Mort subite au cours d’une activité sportive : étude en population générale." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05S009.
Full textAbstract:
Contexte ─ L’incidence, les caractéristiques, et le pronostic (vital et fonctionnel) de la mort subite du sportif n’ont pas été étudiés en population générale. Méthodes ─ Etude observationnelle prospective menée par l’Institut National de la Santé et de la Recherche Médicale en collaboration avec le Service d’Aide Médicale Urgente (SAMU) dans 60 départements français (2005–2010) incluant les sujets de 10 à 75 ans présentant une mort subite (récupérée ou non) au cours d’une activité sportive de loisir ou de compétition. La détection des cas a été assurée par deux sources indépendantes. L’information a été recueillie selon le modèle d’Utstein. Les incidences ont été calculées par million d’habitants et million de participants sportifs, en considérant les 20ème et 80ème percentiles des départements les plus participants. Des analyses complémentaires ont été menées chez les femmes et pour les sports les plus en cause. Compte tenu de disparités régionales importantes en termes de survie, la distribution des facteurs (individuels et communautaires) classiquement associés à la survie (à la sortie de l’hôpital) a été examinée dans 4 groupes de survie (<10%, 10–20, 20–40, et >40%). L’analyse des facteurs associés à la survie a été effectuée par régression logistique.Résultats ─ Au total, 820 cas ont été collectés, et l’incidence totale a été évaluée entre 5 et 17 cas par million d’habitants par an en France. Seulement 6% des cas sont survenus chez le jeune athlète de compétition. Après considération des taux de participation sportive, l’incidence chez l’homme a été estimée entre 11,2 (95% IC 10,4–12,1) et 33,8 (95% IC 30,9–36,8) cas par million de participants et par an, l’incidence chez la femme étant, en comparaison avec l’homme, extrêmement faible, en particulier chez les 40–54 ans avec un risque relatif de 0,03 (95% IC 0,01–0,07). L’incidence augmentait significativement avec l’âge chez l’homme (risque relatif 2,51, 95 % IC 2,10–3,01, quand âge >35 ans), et était plus importante dans certains sports (cyclisme vs. natation, p<0,0001). L’âge moyen des sujets était de 46±15 ans. Des antécédents cardiovasculaires étaient rapportés dans 12% des cas. Le taux de survie moyen à la sortie de l’hôpital était de 15,7% (95% IC 13,2–18,2), avec cependant des disparités départementales majeures (de 0 à 47%), alors que le pronostic neurologique restait favorable chez 80% des survivants. La description en 4 groupes de survie a démontré l’absence de différence significative en termes de caractéristiques des sujets, de circonstances de survenue, de délai de prise en charge, et de mortalité intra-hospitalière. A l’inverse, des différences majeures ont été observées concernant l’initiation du massage cardiaque par le témoin (15% à 81%, p<0,001), le rythme initialement choquable (29% à 79%, p<0,001), le niveau de formation de la population aux premiers secours (p<0,001) et la densité de défibrillateurs extra-hospitaliers dans le département (p<0,001). Le défibrillateur n’a que rarement été utilisé par les témoins avant l’arrivée des premiers secours (<1%). Au final, les facteurs individuels suivants étaient indépendamment associés à la survie à la sortie de l’hôpital : massage cardiaque par témoin (OR 3,73, 95% IC 2,19–6,39, p<0,0001), délai d’intervention (OR 1,32, 95% IC 1,08–1,61, p=0,006), présence d’un rythme choquable initial (OR 3,71, 95% IC 2,07–6,64, p<0,0001). Après ajustement sur les facteurs pronostiques individuels, seul le niveau de formation de la population aux premiers secours restait associé de façon significative à la survie (OR 1,64, 95% IC 1,17–2,31, p=0,004).Conclusions et perspectives ─ La mort subite est un problème de santé publique faisant intervenir les pompiers, le SAMU, les réanimateurs, les cardiologues, les épidémiologistes. Sa prise en charge est nécessairement multidisciplinaire et les progrès viendront d’une action concertée de santé publique. Concernant la mort subite du sportif, nos conclusions sont que (...)<br>Background – Although such data are available for young competitive athletes, the prevalence, characteristics and outcome of sports-related sudden cardiac death have not previously been assessed in the general population.Methods – A prospective and comprehensive national survey was carried out throughout France by the French Institute of Health and Medical Research from 2005 to 2010, involving subjects aged 10–75 years. Case detection for sports-related sudden cardiac death, during competitive or leisure activities, including resuscitated cardiac arrest, was undertaken via emergency medical services (Service d’Aide Médicale Urgente, SAMU) reporting and web-based screening of media releases. Data were collected according to Utstein’s style. Incidence calculations were reported by million of inhabitants as well as million of sports participants. Specific analyses were also carried out among women and specific sports. After having documented major regional survival disparities, we identified to which extent conventional evidence-based individual factors, known to be associated to survival, were distributed among different groups of survival. Moreover, we assessed if functional outcome was variable among groups of survival. Factors associated with survival were analyzed using regression logistic model.Results – The overall burden of sports-related sudden cardiac death was estimated between 5 and 17 cases per million inhabitants per year. Only 6% of cases occurred among young competitive athletes, with a specific incidence calculated to 9.8 (95% CI 3.7–16.0) per million per year. After considering participation rates, incidence in men sport participants was estimated from 11.2 (95% CI 10.4–12.1) to 33.8 (95% CI 30.9–36.8) per million of participants per year, dramatically higher than women-related incidence, particularly in the 45–54 year range (relative risk 0.03, 95% CI 0.01 to 0.07). By contrast with women, the incidence of sports-related sudden cardiac death in men significantly increased over age categories (p<0.0001), and incidence rates were substantially higher in men aged >35 years than men aged 35 years or less (RR 2.51, 95% CI 2.10–3.01). The mean survival rate at hospital discharge was 15.7% (95% CI 13.2–18.2), with major regional disparities among districts (from 0 to 47%), with however a highly similar favorable neurological outcome (80%). No difference was observed regarding subjects’ characteristics and circumstances of occurrence (including presence of witnesses, delays of intervention and public use of automatic external defibrillators) across survival groups. By contrast, major differences were noted regarding bystander initiation of cardiopulmonary resuscitation (15% to 81%, p<0.001) and presence of initial shockable rhythm (29% to 79%, p<0.001). Public use of automatic external defibrillator was dramatically low (<1%). Independent factors for survival included bystander cardiopulmonary resuscitation (OR 3.73, 95% CI 2.19–6.39, p<0.0001), initial shockable rhythm (OR 3.71, 95% CI 2.07–6.64, p<0.0001) and short delay between cardiac arrest and resuscitation (OR 1.32, 95% CI 1.08–1.61, p=0.006). After adjustment on individual factors, only population education to Basic Life Support was significantly associated with survival (OR 1.64, 95% CI 1.17–2.31, p=0.004).Conclusions and perspectives – Sudden cardiac death is a public health issue, with the need for a multidisciplinary approach involving Emergency Cares, Cardiology, and Epidemiology. Regarding sports-related sudden death, our conclusions are the following (...)