Дисертації з теми "Frequency of cardiac reductions"
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1
Haizlip, Kaylan Michelle. "Manipulation and Alterations of the Force Frequency Response in Isolated Cardiac Muscle." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337778482.
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Varian, Kenneth Dean. "Cardiac Myofilament Calcium Sensitivity in Health and Disease." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211898886.
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Tuan, Jiun Haur. "Electrophysiological substrates of atrial fibrillation : a frequency domain study of intra-cardiac electrograms." Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/10105.
Повний текст джерелаАнотація:
The mechanisms responsible for maintenance of AF remain poorly understood. This thesis examines the frequency domain characteristics of AF in order to gain further insights into this arrhythmia. Through a series of studies involving patients undergoing catheter ablation for atrial fibrillation, intra-cardiac electrograms of AF were collected and analysed using Fast Fourier Transform to derive frequency domain parameters of dominant frequency (DF) and organization index (OI). It was found that intravenous flecainide reduced DF of AF, but only an associated increase in OI was predictive of successful return to sinus rhythm. In another study of patients having catheter ablation for persistent AF, a higher OI post-ablation was found to be associated with medium-term freedom of AF, suggesting that OI may be a useful guide to determine the extent of radiofrequency ablation needed. The effects of vagal blockade with atropine were also studied and compared with that of catheter ablation using a stepwise strategy of isolating the pulmonary veins, linear ablation and complex fractionated electrogram ablation, without deliberately targeting ganglionated plexi. This showed that atropine reduced DF and increased OI of AF electrograms, while decreasing mean RR intervals, standard deviation of RR intervals and 5th percentile of RR intervals. The directional changes of all the above parameters mirrored that of catheter ablation, suggesting that vagal blockade and catheter ablation not deliberately aimed at autonomic tissue can have similar effects on the frequency spectrum of AF, probably mediated through modulation of the autonomic tone. The relationship of regional DF and electrogram complexity as assessed by automated measurement of complex fractionated electrogram – mean (CFE-mean) were also compared, pre and post-ablation of the left atrium. There appeared to be only a modest correlation between the two and this was further weakened following ablation, suggesting that these are possibly separate substrate entities.
4
Mackey, Sean Charles. "A dynamic model of radio frequency catheter ablation for the treatment of cardiac arrhythmias." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/187023.
Повний текст джерелаАнотація:
Accurate knowledge of the spatial and temporal temperature distribution within the myocardium would be of value in predicting lesion size and shape during radio frequency (RF) catheter ablation. Finite difference solutions of the Laplace equation, which models power delivery by the RF catheter, and the Bioheat equation, which predicts temperature rise within the myocardium, were developed to accurately model lesion generation during RF ablation. This model included the effects of tissue and electrode heat conduction, tissue perfusion, and the convective losses within the heart chamber. Results indicated that the convective effects of blood flow within the heart chamber over the catheter were significant. More power could be applied before reaching 100°C when these convective cooling effects were included than without them. Electrodes of higher thermal conductivity were determined, by both numerical simulations and in vitro experiments, to promote more heat flux away from the electrode-tissue interface. Consequently, more power could be delivered resulting in larger lesions. The effects of tissue perfusion on intramyocardial temperatures and lesion size were investigated. Perfusion was found to decrease both of these compared to non-perfused tissue. This was particularly evident with longer energy delivery times. The power density model was used to characterize the power density relationship for both single and arrays of multiple catheter electrodes. The results from this model were used to design and implement a multipolar ablation technique. In vitro and in vivo experiments proved this technique was useful for generating longer, deeper lesions than traditional techniques and holds promise for treating atrial fibrillation and flutter. This technique may offer insight into the effects of thermal transfer properties on lesion formation. Furthermore, this model may be useful as a tool to design more effective catheters and energy delivery procedures to produce lesions of desired size and shape.
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Celentano, Laura J. "RFID-assisted wireless sensor networks for cardiac tele-healthcare /." Online version of thesis, 2007. http://hdl.handle.net/1850/5719.
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6
Kassiri, Zamaneh. "Frequency- and hypertrophy-mediated alterations in twitch force and intracellular calcium transients in rat cardiac trabecula." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34088.pdf.
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Cloherty, Shaun Liam Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Cellular interaction in the cardiac pacemaker: a modelling study." Awarded by:University of New South Wales. Graduate School of Biomedical Engineering, 2005. http://handle.unsw.edu.au/1959.4/22512.
Повний текст джерелаАнотація:
In mammalian hearts, initiation of the heartbeat occurs in a region of specialised pacemaker cells known as the sinoatrial node (SAN). The SAN is a highly complex spatially distributed structure which displays considerable cellular heterogeneity and is subject to complex electrotonic interactions with the surrounding atrial tissue. In this study, biophysically detailed ionic models of central and peripheral SAN pacemaker cells are described. These models are able to accurately reproduce experimental recordings of the membrane potential from central and peripheral SAN tissue. These models are used to investigate frequency synchronisation of electrically coupled cardiac pacemaker cells. Based on simulation results presented, it is proposed that cellular heterogeneity in the SAN plays an important role in achieving rhythm coordination and possibly contributes to the efficient activation of the surrounding atrial myocardium. This represents an important, previously unexplored, mechanism underlying pacemaker synchronisation and cardiac activation in vivo. A spatial-gradient model of action potential heterogeneity within the SAN is then formulated using a large-scale least squares optimisation technique. This model accurately reproduces the smooth spatial variation in action potential characteristics observed in the SAN. One and two dimensional models of the intact SAN are then formulated and three proposed models of SAN heterogeneity are investigated: 1) the discrete-region model, in which the SAN consists of a compact central region surrounded by a region of transitional pacemaker cells, 2) the gradient model, in which cells of the SAN exhibit a smooth variation in properties from the centre to the periphery of the SAN, and 3) the mosaic model, in which SAN and atrial cells are scattered throughout the SAN region with the proportion of atrial cells increasing towards the periphery. Simulation results suggest that the gradient model achieves frequency entrainment more easily than the other models of SAN heterogeneity. The gradient model also reproduces action potential waveshapes and a site of earliest activation consistent with experimental observations in the intact SAN. It is therefore proposed that the gradient model of SAN heterogeneity represents the most plausible model of SAN organisation.
8
Chung, Jae-Hoon. "Regulation of Human Cardiac Muscle Contraction and Relaxation in Health and Disease." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1522851185767187.
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9
Ker, James. "Cardiac memory T wave frequency as an electrocardiographic surrogate for structural myocardial alteration in the hearts of dorpersheep." Thesis, University of Pretoria, 2006. http://hdl.handle.net/2263/28373.
Повний текст джерелаАнотація:
In this study we evaluated the validity of well-known human electrocardiographic markers of myocardial pathology in Dorper sheep. These markers are all properties of PVC`s, namely the duration of the QRS complex of PVC`s, the presence of notching of the QRS complex of PVC`s and change in the ST segment of PVC`s. It was shown that these three electrocardiographic phenomena correlate with myocardial pathology in the hearts of Dorper sheep. We also described a new electrocardiographic indicator of myocardial pathology in the hearts of Dorper sheep, namely an increase in the frequency of cardiac memory T waves, induced by PVC`s, as a new electrocardiographic surrogate for myocardial pathology. This study was possible, because we knew from a pilot study that our specific method of inducing right ventricular PVC`s is known to induce structural alterations in the myocardium of Dorper sheep. The guidewire was situated in the right ventricle and we examined the histological appearance of only the left ventricle, in order to exclude any possible changes caused by the wire itself. Although this study was not designed to answer the question of whether PVC`s can be a cause of, rather than a consequence of, structural myocardial disease, it is an important method, because in this way every wether serves as it`s own histological control for electrocardiographic changes. We started with normal Dorper wethers, induced right ventricular PVC`s and these PVC`s had certain characteristics, as described in chapter 3. We know what the normal histological appearance of Dorper wethers are and the electrocardiographic appearance of PVC`s in the normal heart. At the end of the study certain changes appeared in the PVC`s, namely the QRS duration increased, notching appeared and the ST segment disappeared. Furthermore, at this stage the histological appearance of the left ventricle resembled that of myocarditis. At the end of the study (abnormal myocardial histology) we also noted an increase of 42 % in the incidence of cardiac memory T waves following PVC`s, when compared to the beginning of the study (normal myocardial histology). What might the reason be for the abnormal left ventricular histology ? As this study was not designed to answer that question this is open to debate. It might be the anaesthetic, the wire itself or the PVC`s. As already discussed we induced right ventricular PVC`s and afterwards we examined the left ventricles, therefore these histological alterations cannot be a direct consequence of the guidewire itself. It is suggested that it will be worthwhile to explore the possibility that PVC`s may be a cause of myocardial disease and that it is not always a consequence of established myocardial disease.Thesis (PhD (Human Physiology))--University of Pretoria, 2006.
Physiology
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10
Roper, Ryan Todd. "A Study of Radiofrequency Cardiac Ablation Using Analytical and Numerical Techniques." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd262.pdf.
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Brockman, Erik. "TIME-FREQUENCY ANALYSIS OF INTRACARDIAC ELECTROGRAM." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/188.
Повний текст джерелаАнотація:
The Cardiac Rhythm Management Division of St. Jude Medical specializes in the development of implantable cardioverter defibrillators that improve the quality of life for patients diagnosed with a variety of cardiac arrhythmias, especially for patients prone to sudden cardiac death. With the goal to improve detection of cardiac arrhythmias, this study explored the value in time-frequency analysis of intracardiac electrogram in four steps. The first two steps characterized, in the frequency domain, the waveforms that construct the cardiac cycle. The third step developed a new algorithm that putatively provides the least computationally expensive way to identifying cardiac waveforms in the frequency domain. Lastly, this novel approach to analyzing intracardiac electrogram was compared to a threshold crossing algorithm that strictly operates in the time domain and that is currently utilized by St. Jude Medical. The new algorithm demonstrated an equally effective method in identifying the QRS complex on the ventricular channel. The next steps in pursing time-frequency analysis of intracardiac electrogram include implementing the new algorithm on a testing platform that emulates the latest implantable cardioverter defibrillator manufactured by St. Jude Medical and pursuing a similar algorithm that can be employed on the atrial channel.
12
Li, Qian. "Ultrasound Current Source Density Imaging in Live Rabbit Hearts Using Clinical Intracardiac Catheter." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556733.
Повний текст джерелаАнотація:
Ultrasound Current Source Density Imaging (UCSDI) is a noninvasive modality for mapping electrical activities in the body (brain and heart) in 4-dimensions (space + time). Conventional cardiac mapping technologies for guiding the radiofrequency ablation procedure for treatment of cardiac arrhythmias have certain limitations. UCSDI can potentially overcome these limitations and enhance the electrophysiology mapping of the heart. UCSDI exploits the acoustoelectric (AE) effect, an interaction between ultrasound pressure and electrical resistivity. When an ultrasound beam intersects a current path in a material, the local resistivity of the material is modulated by the ultrasonic pressure, and a change in voltage signal can be detected based on Ohm's Law. The degree of modulation is determined by the AE interaction constant K. K is a fundamental property of any type of material, and directly affects the amplitude of the AE signal detected in UCSDI. UCSDI requires detecting a small AE signal associated with electrocardiogram. So sensitivity becomes a major challenge for transferring UCSDI to the clinic. This dissertation will determine the limits of sensitivity and resolution for UCSDI, balancing the tradeoff between them by finding the optimal parameters for electrical cardiac mapping, and finally test the optimized system in a realistic setting. This work begins by describing a technique for measuring K, the AE interaction constant, in ionic solution and biological tissue, and reporting the value of K in excised rabbit cardiac tissue for the first time. K was found to be strongly dependent on concentration for the divalent salt CuSO₄, but not for the monovalent salt NaCl, consistent with their different chemical properties. In the rabbit heart tissue, K was determined to be 0.041 ± 0.012 %/MPa, similar to the measurement of K in physiologic saline: 0.034 ± 0.003 %/MPa. Next, this dissertation investigates the sensitivity limit of UCSDI by quantifying the relation between the recording electrode distance and the measured AE signal amplitude in gel phantoms and excised porcine heart tissue using a clinical intracardiac catheter. Sensitivity of UCSDI with catheter was 4.7 μV/mA (R² = 0.999) in cylindrical gel (0.9% NaCl), and 3.2 μV/mA (R² = 0.92) in porcine heart tissue. The AE signal was detectable more than 25 mm away from the source in cylindrical gel (0.9% NaCl). Effect of transducer properties on UCSDI sensitivity is also investigated using simulation. The optimal ultrasound transducer parameters chosen for cardiac imaging are center frequency = 0.5 MHz and f/number = 1.4. Last but not least, this dissertation shows the result of implementing the optimized ultrasound parameters in live rabbit heart preparation, the comparison of different recording electrode configuration and multichannel UCSDI recording and reconstruction. The AE signal detected using the 0.5 MHz transducer was much stronger (2.99 μV/MPa) than the 1.0 MHz transducer (0.42 μV/MPa). The clinical lasso catheter placed on the epicardium exhibited excellent sensitivity without being too invasive. 3-dimensional cardiac activation maps of the live rabbit heart using only one pair of recording electrodes were also demonstrated for the first time. Cardiac conduction velocity for atrial (1.31 m/s) and apical (0.67 m/s) pacing were calculated based on the activation maps. The future outlook of this dissertation includes integrating UCSDI with 2-dimensional ultrasound transducer array for fast imaging, and developing a multi-modality catheter with 4-dimensional UCSDI, multi-electrode recording and echocardiography capacity.
13
Spicher, Nicolai [Verfasser], and Mark E. [Akademischer Betreuer] Ladd. "Time-frequency analysis of optical and electrical cardiac signals with applications in ultra-high-field MRI / Nicolai Spicher ; Betreuer: Mark E. Ladd." Duisburg, 2020. http://d-nb.info/1221061801/34.
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14
Costa, Gláucia Grüninger Gomes. "Desenvolvimento de sistemas bio-telemétricos para a medida da freqüencia cardíaca e do ritmo respiratório." Universidade de São Paulo, 1986. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-01062009-112145/.
Повний текст джерелаАнотація:
O desenvolvimento da Física tem possibilitado sua atuação em vários campos, e mais recentemente, na Medicina, onde estudos da Freqüência Cardíaca e do Ritmo Respiratório fornecem informações importantes acerca de processos fisiológicos e podem ser um útil instrumento diagnóstico e terapêutico. Nestes estudos, em muitos casos, necessita-se que as variáveis sejam monitoradas telemétricamente, como a observação de atletas e pacientes pré e pós-enfartados durante a prática desportiva, e estudos de animais em seu habitat natural. Desenvolvemos, portanto, um protótipo capaz de medí-las por métodos não invasivos (métodos que dispensam urna exposição cirúrgica), baseando-se na aplicação do Efeito Doppler Ultrasônico e no Movimento Mecânico do Tórax. Este protótipo consta de um conjunto de transmissores e receptores que captam e Freqüência Cardíaca e o Ritmo Respiratório, registrando de forma audível, gráfica e numérica, conforme tempos pré-estabelecidos.The development of physics made action in various fields possible, and more recently, in Medicine, studies of heart frequency and breathing rhythm give important information about physiological status and are useful for diagnostics and therapeutics. In these studies, in many cases, it is necessary that variables could be monitored by telemetry, as p.e. observation of athletes and also before and post-glutted patients during sport practices, and studies of animals in their own habitat. We are developing, therefore, a telemetric prototype which is capable of measuring them by non-invasive methods (methods that exempt a surgical exposure), based upon application of the Ultrasonic Doppler effect and of the Mechanical Movement of thorax. This prototype consist of a group of transmitters and receivers which are getting heart beat frequency and breathing rhythm recorded by such forms: audible, graphic and numerical, in before established periods.
15
Zeder, Marius Philipp [Verfasser], and Thomas [Akademischer Betreuer] Bein. "Frequency of delirium in non-cardiac surgical and medical intensive-care patients — results from a comparative, prospective, observational study / Marius Philipp Zeder ; Betreuer: Thomas Bein." Regensburg : Universitätsbibliothek Regensburg, 2019. http://d-nb.info/1184573913/34.
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Coelho, Andrês Sales. "Parâmetros fisiológicos de cães submetidos a treinamento em esteira." Universidade Federal de Viçosa, 2007. http://locus.ufv.br/handle/123456789/4938.
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Lack of physical activity and highly caloric food have deeply affected canine health, leading them to develop many kinds of diseases related to the heart, obesity, joints and even behavior. In this way, preventive and curative steps such as physical activities and canine sports have been taken in order to guarantee that the dogs have a long and healthful life. However, for those steps to be taken, it is essential that the animals have a good physical conditioning, which can be determined by many different physiological parameters. The present work had as objective to evaluate the physiological parameters for dogs trained in a treadmill. Eight animals of different breeds, fed with the same commercial ration and lodged in individual kennels, were used. After clinical evaluation, the dogs rested 30 days. On the 19th day, the animals went through an evaluation of the following physiological parameters: cardiac frequency (CF), respiratory frequency (RF), body temperature (BT), lactate and sanguineous glucose. After that period, they were submitted to a test of gradual load in a treadmill, to measure the parameters in the maximum effort, returning to the point of rest, which was called recovery time. Using these data, the dogs inferior and superior limits of the CF as well as the intensity of the training were determined. The animals were divided in groups 1 and 2, which trained five and three times a week, respectively, in alternated days for five weeks. After that, they were, once again, submitted to the test of gradual load to measure the values of the physiological parameters. Among the dogs of the first group, it was observed a reduction of the CF (P<0.05), during the test of maximum effort, since the higher estimative of 214 bpm dropped to 205.33 bpm. These results suggest that there was an improvement in the cardiovascular conditioning for this group. For the animals of group 1, the CF at rest, after training, was lower compared to the period before the training, (P<0.05), going from 75 ± 5.65 to 67 ± 6.83 bpm. Comparing the before and after periods of exercises, the recovery of the CF was faster (P<0.05) for the dogs in group 2. The training five days a week offered a reduction (P<0.05) in the sanguineous lactate concentration at the same training speed, before and after training, suggesting a better physical conditioning. For the two groups, after training, it was observed significant alterations in the BT, remaining lower during all the test of progressive load. Concerning the RF and glucose, it was not observed significant differences in both groups. To sum up, the changes in the CF, BT and lactate indicate that there was an improvement in the physical conditioning of the dogs which trained five days a week, reason why this protocol is recommended.
A falta de atividade física de cães aliada a uma alimentação de alto teor energético têm afetado seriamente a saúde dos cães, levando-os a desenvolver vários tipos de problemas associados ao coração, à obesidade, às articulações e até mesmo ao comportamento. Desta forma, visando oferecer condições para que os animais tenham uma vida longa e saudável, medidas preventivas e curativas, como práticas de atividades físicas e esportes caninos, têm sido utilizadas. No entanto, para o desenvolvimento dessas atividades é fundamental um bom condicionamento físico, o que pode ser determinado por vários parâmetros fisiológicos. O presente trabalho teve como objetivo a avaliação dos parâmetros fisiológicos de cães treinados em esteira. Foram utilizados oito animais de raças diferentes, alimentados com a mesma ração comercial e alojados em canis individuais. Depois de uma avaliação clínica, os cães passaram por período de 30 dias de repouso, sendo que no 19º dia foram obtidos os seguintes parâmetros fisiológicos: freqüência cardíaca (FC), freqüência respiratória (FR), temperatura corporal (TC), lactato e glicose sangüínea. Após esse período, eles foram submetidos a um teste de cargas progressivas em esteira, para se determinar os mesmos parâmetros no esforço máximo e até retornarem aos valores de repouso, o que foi chamado de período de recuperação. A partir desses dados, foram determinados os limites inferior e superior da FC dos cães e a intensidade dos exercícios. Os animais foram divididos nos grupos 1 e 2, que treinaram 5 e 3 vezes por semana, respectivamente, em dias alternados durante cinco semanas. Depois disso, foram novamente submetidos ao teste de cargas progressivas para que os valores dos parâmetros fisiológicos fossem novamente determinados. Nos cães do primeiro grupo, foi observada uma diminuição da FC (P<0,05), durante o teste de esforço máximo, sendo que a máxima estimada de 214 bpm passou para 205,33 bpm. Esses resultados sugerem que houve uma melhora no condicionamento cardiovascular para esse grupo. Para os animais do grupo 1, a FC referente ao repouso, após o treinamento foi menor que antes do treinamento (P<0,05), variando de 75 ± 5,65 para 67 ± 6,83 bpm. Quando comparada antes e após o treinamento, a recuperação da FC foi mais rápida (P<0,05) para os cães do grupo 2. O treinamento 5 vezes por semana proporcionou diminuição (P<0,05) da concentração de lactato sanguíneo em uma mesma velocidade de teste antes e após o treinamento, sugerindo uma melhora no condicionamento físico dos cães. Para os dois grupos após o treinamento, foram observadas reduções significativas na TC, que se manteve menor durante todo o teste de cargas progressivas. Quanto à FR e glicose não foram observadas diferenças significativas em ambos os grupos. Concluindo, as alterações verificadas na FC, TC e lactato indicam que houve melhora no condicionamento físico dos cães treinados 5 vezes por semana, recomendando-se esse protocolo.
17
Barbosa, Daniel. "Automated assessment of cardiac morphology and function : An integrated B-spline framework for real-time segmentation and tracking of the left ventricle." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0111.
Повний текст джерелаАнотація:
L’objectif principal de cette thèse est le développement de techniques de segmentation et de suivi totalement automatisées du ventricule gauche (VG) en RT3DE. Du fait de la nature difficile et complexe des données RT3DE, l’application directe des algorithmes classiques de vision par ordinateur est le plus souvent impossible. Les solutions proposées ont donc été formalisées et implémentées de sorte à satisfaire les contraintes suivantes : elles doivent permettre une analyse complètement automatique (ou presque) et le temps de calcul nécessaire doit être faible afin de pouvoir fonctionner en temps réel pour une utilisation clinique optimale. Dans ce contexte, nous avons donc proposé un nouveau cadre ou les derniers développements en segmentation d’images par ensembles de niveaux peuvent être aisément intégrés, tout en évitant les temps de calcul importants associés à ce type d’algorithmes. La validation clinique de cette approche a été effectuée en deux temps. Tout d’abord, les performances des outils développés ont été évaluées dans un contexte global se focalisant sur l’utilisation en routine clinique. Dans un second temps, la précision de la position estimée du contour du ventricule gauche a été mesurée. Enfin, les méthodes proposées ont été intégrées dans une suite logicielle utilisée à des fins de recherche. Afin de permettre une utilisation quotidienne efficace, des solutions conviviales ont été proposées incluant notamment un outil interactif pour corriger la segmentation du VGThe fundamental goal of the present thesis was the development of automatic strategies for left ventricular (LV) segmentation and tracking in RT3DE data. Given the challenging nature of RT3DE data, classical computer vision algorithms often face complications when applied to ultrasound. Furthermore, the proposed solutions were formalized and built to respect the following requirements: they should allow (nearly) fully automatic analysis and their computational burden should be low, thus enabling real-time processing for optimal online clinical use. With this in mind, we have proposed a novel segmentation framework where the latest developments in level-set-based image segmentation algorithms could be straightforwardly integrated, while avoiding the heavy computational burden often associated with level-set algorithms. Furthermore, a strong validation component was included in order to assess the performance of the proposed algorithms in realistic scenarios comprising clinical data. First, the performance of the developed tools was evaluated from a global perspective, focusing on its use in clinical daily practice. Secondly, also the spatial accuracy of the estimated left ventricular boundaries was assessed. As a final step, we aimed at the integration of the developed methods in an in-house developed software suite used for research purposes. This included user-friendly solutions for efficient daily use, namely user interactive tools to adjust the segmented left ventricular boundaries
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Vilhegas, Leonardo Zane. "Desenvolvimento de um protótipo para monitoração de saturação de oxigênio e freqüência cardíaca para roedores." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-20072009-180319/.
Повний текст джерелаАнотація:
A utilização de equipamentos para monitoração de parâmetros fisiológicos não é apenas crucial em pacientes que são submetidos a alguns procedimentos médicos, mas é também de extremo valor para animais em uso similar. Este projeto tem como principal objetivo o desenvolvimento de um sistema de monitoração de saturação de oxigênio e freqüência cardíaca para roedores; tal sistema é composto por um dispositivo protótipo compacto e sensor óptico. No presente trabalho, foram utilizadas as tecnologias dos microcontroladores da Microchip para realizar as diversas digitalizações; a tecnologia USB, para realizar a comunicação com computadores e o desenvolvimento da interface desenvolvida com o software disponível da National Instruments, o LabVIEW. Neste estudo, o sistema desenvolvido foi empregado em camundongos e foram realizadas diversas avaliações em laboratório e em campo para a validação do dispositivo protótipo. Os batimentos cardíacos e a saturação de oxigênio, tanto em repouso quanto em movimento, foram detectados pelo protótipo. Os valores de freqüência cardíaca variaram entre 545 e 700 bpm enquanto os valores de saturação de oxigênio variaram entre 80 a 95%.The equipments use to monitoring physiological parameters isnt just crucial in patients who are submitted to some medical procedures but it is also of extreme value for animals in similar use. This project has as main objective the development of a monitor oxygen saturation and cardiac frequency for mice; the system is compound of a compact prototype device and optic sensor. In the present work, the Microchip microcontrollers technologies had been used, to realize many digitalization; the USB technology interface, to realize the communication with computers and the interface development developed with the available National Instruments software, the LabVIEW. In this study, the developed system was used in mice and have been realized many evaluations in laboratory and field for the prototype validation device. The cardiac beatings and oxygen saturation, as much in rest how in movement they had been detected by the prototype. The values of heart rate had varied of 545 to 700 while the values of oxygen saturation had varied of 80 to 95%.
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Brito, Deusdete de Sousa. "Cálculo da Frequência Instantânea Cardíaca Utilizando o Algoritmo LMS e uma Interface de Aquisição de Dados." Universidade Federal do Maranhão, 2002. http://tedebc.ufma.br:8080/jspui/handle/tede/318.
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In this work we consider the calculation of the heart instantaneous frequency from the estimate of the weights, gotten through LMS algorithm, (Least Mean Squares) when functioning as spectrum analyzer. It is known that the electrocardiogram (ECG) is a signal that is characterized for a repetitive regularity, which can be called quasi-periodicity. We explore this characteristic to extract the instantaneous frequency of the referred signal. For this, we use the LMS as a spectral analyzer. We use as reference inputs pairs of sines and cosines, inside the frequency band where if it finds the frequency of the desired signal, namely, the heart frequency. The algorithm estimates the frequency desired in real time, with the signal acquired through a data acquisition interface Intel 80C31. The results obtained show that the algorithm can be recommended for this purpose, as besides being easily implemented and generating small computational load it estimates the heart instantaneous frequency with a relative mean error of 0.025 which represent a difference of 18.89% between the two methods.
Neste trabalho propomos o cálculo da frequência instantânea cardíaca a partir da estimativa do espectrograma dos pesos sinápticos, obtidos através do algoritmo LMS, (Least Mean Square) quando funcionando como analisador de espectro. Sabe-se que o eletrocardiograma (ECG) é um sinal que se caracteriza por uma regularidade repetitiva, que se pode chamar quasiperiodicidade. Exploramos aqui essa característica para extrair a frequência instantânea do referido sinal. Para isso, utilizamos o LMS como analisador de espectro. Utilizamos como entradas de referència pares de senos e cossenos, dentro da faixa de frequência em que se encontra a frequência do sinal desejado, no caso, a frequência cardíaca. O algoritmo estima a frequência desejada em tempo real, com obtenção do sinal através de uma interface de aquisição de dados Intel 80C31. Os resultados obtidos mostraram que o algoritmo pode ser recomendado pra esta finalidade, pois além de ser facilmente implementável e por gerar pequena carga computacional ele estimou a frequência instantânea cardíaca com um erro relativo médio de 0.025 que representa uma diferença de 18.89% entre os dois métodos.
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Marques, JoÃo Alexandre LÃbo. "SISCTG- an intelligent systems for classification of cardiotocography signals for help diagnosis doctor." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2046.
Повний текст джерелаАнотація:
nÃo hÃThe accurate analysis of the fetal heart rate (FHR) and its correlation with uterine contractions (UC) allows the diagnostic and the anticipation of many problems related to fetal distress and the preservation of his life. This dissertation presents the results of an hibrid system based on a set of deterministic rules and fuzzy inference system developed to analyze FHR and UC signals collected by cardiotocography (CTG) exams. The studied variables are basal FHR, short and long term FHR variability, transitory accelerations and decelerations, these lasts classified by their type and number of ocurrencies. The system output is a first level diagnostics based on those input variables. The SISCTG system is developed using the Matlab version 7 script language. Tests and modeling issues used the Matlab Fuzzy Toolbox. The project also supports a multi-institutional agreement between Brazil and Germany, among the DETI - Departamento de Engenharia de TeleinformÂatica of the UFC â Universidade Federal do CearÂa, the MEAC - Maternidade-Escola Assis Chateaubriand), the TUM - Technische UniversitÃt MÃnchen, the Bundeswehr UniversitÃt MÃnchen and the Trium Analysis Online GmbH. The SISCTG results are very promising, correctly classifying all normal exams. This is the expected behavior, once CTG exams are classified as of low specificity, with the most interest focused in finding pathologies aspects, but not precisely identifying them. These results allow the projection of improvements to the proposed system, inserting new input variables, for example. The system validation methodology was based on the knowledge of Brazilian and German obstetricians.
A anÃlise acurada da freqÃÃncia cardÃaca fetal (FCF ou FHR - Fetal Heart Rate) correlacionada com as contraÃÃes uterinas maternas (UC - Uterine Contractions) permite gerar diagnÃsticos e a conseqÃente antecipaÃÃo de problemas diversos relativos ao bem estar fetal e a preservaÃÃo de sua vida. O presente trabalho apresenta os resultados de um sistema hibrido baseado em regras determinÃsticas e em um mÃdulo de inferÃncia nebuloso (fuzzy) para anÃlise de sinais de FCF e UC coletados atravÃs de exames denominados cardiotocografias (CTG). As variÃveis analisadas sÃo o valor basal da FCF, sua variabilidade de curto e de longo prazo, aceleraÃÃes transitÃrias e desaceleraÃÃes, sendo estas classificadas por seu tipo e pelo nÃmero de ocorrÃncias. A saÃda do sistema à o diagnÃstico em primeiro nÃvel, baseado nas informaÃÃes das variÃveis de entrada definidas. O sistema SISCTG à desenvolvido na linguagem de scripts do programa Matlab versÃo 7. Modelagens e testes sÃo realizados utilizando-se o Fuzzy Toolbox do programa Matlab. O projeto tambÃm conta com uma parceria multi-institucional entre o Brasil e a Alemanha, envolvendo a Universidade Federal do Cearà (UFC), atravÃs do Departamento de Engenharia de TeleinformÃtica (DETI) e da Maternidade-Escola Assis Chateaubriand (MEAC), a Technische UniversitÃt MÃnchen (TUM), a Bundeswehr UniversitÃt MÃnchen e a empresa Trium Analysis Online GmbH. Os resultados obtidos pelo SISCTG sÃo bastante promissores, classificando todos os exames normais corretamente. Este à o comportamento esperado, uma vez que CTGs sÃo exames de baixa especificidade, tendo como interesse maior encontrar indÃcios de patologias, sem a necessidade de identificÃ-las precisamente. Estes resultados permitem projetar o aperfeiÃoamento deste sistema com a inserÃÃo, por exemplo, de novas variÃveis de entrada. SÃo realizados procedimentos de validaÃÃo com mÃltiplos especialistas na Ãrea obstÃtrica tanto no Brasil quanto na Alemanha.
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Černiauskaitė, Ina. "Slaugytojo vaidmuo prižiūrint centrinius venos kateterius reanimacijos ir intensyvios terapijos skyriuje." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20140626_192344-28544.
Повний текст джерелаАнотація:
Darbo tikslas. Ištirti slaugytojo vaidmenį prižiūrint centrinių venos kateterius reanimacijos ir intensyvios terapijos skyriuje. Darbo uždaviniai. Nustatyti centrinės venos kateterizacijos įtaką pagrindiniams pacientų gyvybinių funkcijų rodikliams. Ištirti, kokios dažniausiai pasitaiko centrinių venų komplikacijos ir jų priežastis. Išsiaiškinti slaugytojo veiksmus, padedančius sumažinti komplikacijų atsiradimo riziką. Ištirti reanimacijos ir intensyvios terapijos slaugytojų centrinių venų kateterių priežiūros žinias . Tyrimo medžiaga ir metodai. Teorinė mokslinės literatūros, leidinių, publikacijų apžvalga. Dokumentų analizės metodas (panaudotas pacientų su centrinių venų kateteriais tyrimui). Asmeninio stebėjimo metodas. Atliktas 97 pacientų po centrinių venų kateterizacijų, pagrindinių gyvybinių funkcijų stebėjimas reanimacijos ir intensyvios terapijos skyriuje. Reanimacijos ir intensyvios terapijos slaugytojų anketinė apklausa žinioms ištirti, dirbant su centrinių venų kateteriais. Gautų rezultatų aptarimas ir jų analizė. Statistinė analizė atlikta naudojant „Microsoft Office Excel 2003“ ir SPSS 16,0 for Windows versijos statistinę programą Tyrimo rezultatai ir išvados. Tam, kad būtų išsiaiškintas slaugytojos vaidmuo prižiūrint centrinius venos kateterius buvo atliktas stebėjimo tyrimas pacientų po centrinių venos kateterizacijų. Tyrimo metu Vilniaus Universiteto ligoninėje Santariškių klinikos I reanimacijos ir intensyvios terapijos skyriuje nustatyta, kad centrinių venos... [toliau žr. visą tekstą]The goal of the study: to determine the role of a nurse in the maintenance of the central venous catheter (CVC) in the resuscitation and intensive care department. The objectives: to determine the influence of the central venous catheterization to the indexes of the main vital functions of the patients. To specify the most frequent venous complications and the reasons why they occur. To find out what nurses’ actions can reduce the risk of complications. To examine the professional knowledge of the nurses who work with central venous catheters in the resuscitation and intensive care departments. Research material and methods. Theoretical review of scientific literature, publications and articles. Document analysis method (utilized for the reasearch of patient’s with central venous catheters). Personal observation method. Observation of the main vital functions of 97 patients after central venous catheterization in the resuscitation and intensive care department. The questionnaire-based survey in order to examine the professional knowledge of the nurses who work with central venous catheters in the resuscitation and intensive care department. Discussion and analysis of the obtained results. Analysis of the statistical data using the Microsoft Office Excel 2003 and SPSS 16,0 for Windows software packages. The results and conclusions of the study. In order to determine the role of a nurse for the maintenance of central venous catheter, the observation research was conducted with... [to full text]
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Lucas, Julie. "Intégrité fonctionnelle chez le poisson zèbre, Danio rerio, exposé à des concentrations sublétales d’hydrocarbures aromatiques polycycliques." Thesis, La Rochelle, 2013. http://www.theses.fr/2013LAROS422/document.
Повний текст джерелаАнотація:
L’anthropisation croissante des zones côtières induit le rejet dans les écosystèmes aquatiques d’Hydrocarbures Aromatiques Polycycliques (HAP). En plus de la concentration et de la voie de contamination considérées, leurs effets dépendent du stade de développement de l’organisme. Dans ce contexte, l’objectif de cette étude était d’évaluer les effets d’une contamination par voie trophique à des concentrations sublétales de HAP sur une espèce modèle, le poisson zèbre Danio rerio. Deux types de mélanges de HAP, pyrolytique et pétrogénique, représentatifs de ce qui est rencontré en milieu contaminé ont été testés via des expositions chroniques. Au niveau individuel, les réponses biologiques ont été évaluées au travers de performances physiologiques considérées comme des mesures indirectes de la fitness : la capacité métabolique aérobie, les performances de nage et la réponse de fuite. A l’échelle sub-individuelle, l’exposition aux HAP a été évaluée sur le cœur via la mesure du rythme cardiaque. Ces paramètres biologiques ont été mesurés (i) à différents temps d’exposition des poissons ainsi que (ii) sur leur descendance dans le but d’évaluer l’effet parental de la contamination. Les résultats mettent en évidence une diminution de la capacité métabolique aérobie chez la descendance de poissons contaminés aux HAP d’origine pyrolytique. Chez les poissons adultes directement exposés aux HAP de type pétrogénique, une réduction de la capacité métabolique a également été observée, associée à une réduction de la vitesse de nage critique. Cette étude contribuera à établir une vision globale des effets de l’exposition aux HAP et à mieux comprendre les mécanismes régulant des fonctions biologiques clés dans la survie d’un organisme tout au long de son cycle de vieThe increase of anthropogenic activities on coastal areas induces discharges of polycyclic aromatic hydrocarbons in aquatic ecosystem. PAHs effects depend on their concentration and the way of contamination, but also on the different developmental stages of the organism. In this context, the aim of our study was to observe the effects of an exposure to two PAHs mixes, pyrolytic and petrogenic, on the model species zebrafish Danio rerio. These chronicle exposures at sub-lethal concentrations were representative of contaminated areas. Biological responses of fish were estimated at individual levels through the assessment of aerobic metabolic scope, swimming and escape performance, which are considered to be relevant indirect measures of the fitness. Furthermore, measurements of cardiac frequency allowed observing PAHs impairments at sub-individual levels. These physiological performances were estimated (i) a several times of exposure (i.e. from 2-months juveniles to 6-months adults) and (ii) on their progeny, in order to observe parental effect of the PAHs exposure. An increase of aerobic metabolic scope was observed on the progeny of fish contaminated by pyrolytic mix. Regarding petrogenic PAHs exposure, the increase of aerobic metabolic scope was associated to increase of critical swimming speed in adults. This study will contribute to establishing a global vision of PAHs exposure impairments and to a better understanding of the regulating mechanisms of the main biological functions on which organism survival depends
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Gercek, Cihan. "Immunité des implants cardiaques actifs aux champs électriques de 50/60 Hz." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0226/document.
Повний текст джерелаАнотація:
La directive européenne 2013/35/UE précise les exigences minimales pour la protection des travailleurs exposés aux champs électromagnétiques et définit les porteurs d’implants comme travailleurs à risques particuliers. Concernant les porteurs de défibrillateur automatique implantable (DAI) ou de stimulateur cardiaque (SC), l’exposition au champ électrique ou magnétique d’extrêmement basse fréquence crée des inductions à l'intérieur du corps humain pouvant générer une tension perturbatrice susceptible de causer le dysfonctionnement de l’implant. Le sujet de ce travail de thèse porte sur la compatibilité électromagnétique des implants cardiaques soumis à un champ électrique basses fréquences (50/60 Hz). Des simulations numériques ont été effectuées afin de concevoir un banc expérimental pour l’exposition de fantômes incluant des stimulateurs ou des défibrillateurs implantables. Une étude expérimentale a permis d’établir par provocation les seuils de champ électrique permettant d’éviter tout dysfonctionnement éventuel de l’implant. Dans la partie simulation numérique ; un modèle humain virtuel (fantôme numérique contenant un implant cardiaque) a été placé en position debout sous une exposition verticale à un champ électrique. La méthode des éléments finis a été utilisée pour définir les phénomènes induits au niveau de l’implant cardiaque avec une résolution de 2mm (logiciel CST®). Dans la partie expérimentale, un banc d'essai dimensionné pour permettre de générer un champ électrique pouvant atteindre 100 kV/m aux fréquences 50-60 Hz a été conçu, optimisé et réalisé afin d’analyser le comportement des implants cardiaques. Plusieurs configurations ont été étudiées. Sur 54 implants cardiaques actifs testés (43 stimulateurs et 11 défibrillateurs) à des niveaux de champs électriques très élevés (100 kV/m) générés par notre dispositif expérimental, aux fréquences de 50-60 Hz, aucune défaillance n’a été observée pour des niveaux d’exposition publics et pour la plupart des configurations (+99%) sauf pour six stimulateurs cardiaques dans le cas d’une configuration « pire cas » peu réaliste en clinique : mode unipolaire avec une sensibilité maximale et en détection auriculaire. Les implants configurés avec une sensibilité nominale en mode bipolaire résistent bien à des champs électriques dépassant les valeurs seuils telles que définies par 2013/UE/35The European Directive 2013/ 35 / EU specify minimum requirements for the protection of workers exposed to electromagnetic fields and define with implants as “workers at particular risk”. Regarding the implantable cardioverter defibrillator wearers (ICD) or pacemaker (PM), exposure to electric or magnetic field of extremely low frequency creates inductions inside the human body that generate interference voltage which may cause the dysfunction of the implant. This thesis investigates the electromagnetic compatibility of cardiac implants subjected to an electric field low frequency (50/60 Hz). Computational simulations are effectuated in order to design an experimental bench for the exposure of a phantom including pacemakers or implantable defibrillators. A provocative study is established to define the electric field thresholds for preventing any malfunction of the implant. In numerical simulations; a virtual human model (digital phantom containing a cardiac implant) was placed in an upright position in a vertical exposure to an electric field. The finite element method was used to define the inductions in the cardiac implant level with a resolution of 2 mm (CST® software). In the experimental part, a test bench designed to allow generating an electric field up to 100 kV / m at frequencies 50-60 Hz was constructed, optimized and employed to investigate the behavior of cardiac implants.Several configurations were studied. 54 active cardiac implants (43 pacemakers and 11 defibrillators) are submitted to very high electric field of 50-60 Hz (up to 100 kV / m) inside the experimental bench. No failure was observed for public exposure levels for most configurations (+ 99%) except for six pacemakers in the case of a configuration clinically almost inexistent: unipolar mode with maximum sensitivity and atrial sensing.The implants configured with a nominal sensitivity in bipolar mode are resistant to electric fields exceeding the low action levels (ALs), even for the most high ALs, as defined by 2013 / 35 / EU
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Jančová, Ivana. "Porovnání parametrů pro stanovení srdeční asynchronie z vysokofrekvenčního signálu elektrokardiogramu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221328.
Повний текст джерелаАнотація:
This thesis deals with the analysis of high-frequency ECG, namely by parameters for the determination of cardiac asynchrony from the amplitude envelopes ultra-high-frequency ECG. In the theoretical part is described the conventional and high-frequency ECG, procedure of their scanning and parameters of the acquired record. Also is described the electrical conduction system of the heart and its blockade. This issue is followed by chapters about cardiac asynchrony and its treatments by biventricular pacemaker – resynchronization therapy. The chapter about resynchronization includes a description of the methods used for the indication for therapy based on conventional and high-frequency ECG. In the practical part are proposed new parameters for determining heart asynchrony from high-frequency ECG, programmed their detection in environment MATLAB and described realization of detection and obtained results. In the last part of thesis is described statistical evaluation of data and is decided about suitability of use the proposed parameters.
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Богуш, В. Л., С. В. Гетманцев, В. Н. Фарионов, А. А. Раевский, И. Н. Смирнова, Д. А. Харько, V. Bogush та ін. "Изменение сердечно-сосудистой системы при акклиматизации в горах". Thesis, 2014. http://eir.nuos.edu.ua/xmlui/handle/123456789/4991.
Повний текст джерелаАнотація:
Изменение сердечно-сосудистой системы при акклиматизации в горах / В. Л. Богуш, С. В. Гетманцев, В. Н. Фарионов, А. А. Раевский, И. Н. Смирнова, Д. А. Харько // Матеріали XIV міжнар. наук.-практ. конф. "Актуальні проблеми сучасної біології та здоров'я людини". – Миколаїв : МНУ ім. В. О. Сухомлинського, 2014. – Вип. 14. – C. 10–13.Визначалася частота серцевих скорочень, анаеробно-пульсовий поріг у спортсменів-бігунів у різних умовах, на рівнині і в горах, при режимах тренування, що змінюються. Отримані дані дозволяють оптимізувати процес тренування на різних етапах підготовки до змагань.
Frequency of cardiac reductions, anaerobic-pulse threshold for sportsmen-runners was determined, in different terms, on a plain and in mountains, at the modes there are trainings which change. Information is got allow to optimize a training process on the different stages of preparation to the competitions.
В разных условиях, на равнине и в горах, при изменяющихся режимах тренировки определялась частота сердечных сокращений, уровень анаэробного порога у спортсменов-бегунов. Полученные данные позволяют оптимизировать процесс тренировки на разных этапах подготовки к соревнованиям.
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(6620237), Sokheang Thea. "Identification of Stiffness Reductions Using Partial Natural Frequency Data." Thesis, 2019.
Знайти повний текст джерелаАнотація:
In vibration-based damage detection in structures, often changes in the
dynamic properties such as natural frequencies, modeshapes, and derivatives of
modeshapes are used to identify the damaged elements. If only a partial list of
natural frequencies is known, optimization methods may need to be used to
identify the damage. In this research, the algorithm proposed by Podlevskyi & Yaroshko (2013) is used to determine
the stiffness distribution in shear building models. The lateral load resisting
elements are presented as a single equivalent spring, and masses are lumped at
floor levels. The proposed method calculates stiffness values directly, i.e., without optimization, from the known partial list of natural frequency data and mass
distribution. It is shown that if the number of stories with reduced
stiffness is smaller than the number of known natural frequencies, the stories
with reduced stiffnesses can be identified. Numerical studies on building
models with two stories and four stories are used to illustrate the solution
method. Effect of error or noise in given natural frequencies on stiffness
estimates and, conversely, sensitivity of natural frequencies to changes in
stiffness are studied using 7-, 15-, 30-, and 50-story numerical models. From
the studies, it is learnt that as the number of stories increases, the natural
frequencies become less sensitive to stiffness changes. Additionally, eight
laboratory experiments were conducted on a five-story aluminum structural
model. Ten slender columns were used in each story of the specimen. Damage was
simulated by removing columns in one, two, or three stories. The method can
locate and quantify the damage in cases presented in the experimental studies. It
is also applied to a 1/3 scaled 18-story steel moment frame building tested on
an earthquake simulator (Suita et al., 2015) to identify the reduction in the
stiffness due to fractures of beam flanges. Only the first two natural
frequencies are used to determine the reductions in the stiffness since the
third mode of the tower is torsional and no reasonable planar spring-mass model
can be developed to present all of the translational modes. The method produced possible cases of the
softening when the damage was assumed to occur at a single story.
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Ogimoto, Kayoko. "Cortisol, abdominal obesity, and reductions in inflammation after cardiac rehabilitation in non-diabetic coronary patients." Thesis, 2000. http://hdl.handle.net/1957/32661.
Повний текст джерелаАнотація:
Abdominal obesity is a part of insulin resistance syndrome that is closely
linked to increased risk of coronary artery disease (CAD). Because fat tissue acts as
an endocrine target and source of hormone production, increased metabolism or
production of chemical messengers in fat tissue may result in metabolic perturbations
that contribute to occurrence and recurrence of coronary events. This dissertation
research entails two separate approaches. The first study, a cross-sectional analysis,
sought to determine whether serum cortisol responses to oral glucose loading are
associated with abdominal obesity, non-esterified fatty acid (NEFA) suppression, and
self-reported symptoms of depression in 26 non-diabetic coronary patients. We
conclude that lower cortisol responses to oral glucose loading are associated with
abdominal obesity, reduced NEFA suppression, and fewer symptoms of depression
(P���0.028). Future prospective studies should determine whether psychosocial risk
factors, such as depression and anxiety, increase cortisol production, whether increases
in cortisol production act synergistically with a positive energy balance in the
development of abdominal obesity, and whether increases in abdominal obesity lead to
increases in cortisol metabolism and insulin resistance.
C-reactive protein (CRP) is a marker of low-grade inflammation that is
associated with increased risk for recurrent events in coronary patients. Fat tissue also
secretes proinflammatory cytokines that stimulate hepatic production of CRP. Thus,
the second study, an intervention study, sought to determine whether the first three
months of cardiac rehabilitation could reduce serum concentrations of CRP and the
proinflammatory cytokine, tumor necrosis factor-�� (TNF-��), in our non-diabetic
coronary patients (N=26). Results from the intervention study showed significant
reductions in serum CRP levels (P=0.012) that were associated with reductions in
waist circumferences after cardiac rehabilitation (r=0.39, P=0.049). However,
changes in serum TNF-�� levels after cardiac rehabilitation were nonsignificant
(P=0.869). Thus, we conclude that cardiac rehabilitation may reduce the severity of
low-grade inflammatory conditions, in part, through reductions in waist circumference
in non-diabetic coronary patients.Graduation date: 2001
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Lai, Yu-Chi. "Lesion size estimator for cardiac radio-frequency ablation /." 2009. http://www.library.wisc.edu/databases/connect/dissertations.html.
Повний текст джерела
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Zhang, Jie. "Noncontact radio-frequency cardiac ablation for obtaining deeper lesions." 2002. http://catalog.hathitrust.org/api/volumes/oclc/50179384.html.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 10-12).
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Lau, Angus. "Frequency-selective Methods for Hyperpolarized 13C Cardiac Magnetic Resonance Imaging." Thesis, 2012. http://hdl.handle.net/1807/34779.
Повний текст джерелаАнотація:
Heart failure is a complex clinical syndrome in which the heart cannot pump sufficient blood and nutrients to the organs in the body. Increasingly, alterations in cardiac energetics are being implicated as playing an important role in the pathogenesis of heart failure. An understanding of specific metabolic switches which occur during the development of heart failure in patients would be greatly beneficial as a new diagnostic method and for the development of new therapies for patients with failing hearts.
This thesis deals with the non-invasive assessment of metabolism in the heart. New magnetic resonance imaging (MRI) methods for metabolic characterization of the heart using hyperpolarized carbon-13 MRI are presented. Spatially resolved images of hyperpolarized 13C substrates and their downstream products can provide insight into real-time metabolic processes occurring in vivo, within minutes of injection of a pre-polarized 13C-labeled substrate. Conventional 3D spectroscopic acquisitions require in excess of 100 excitations, making it challenging to acquire full cardiac and respiratory-gated, whole-heart metabolic volumes.
Each of the developments described in this thesis is intended to advance cardiac hyperpolarized 13C metabolic imaging towards a routine, clinical exam which can be used for prognosis and treatment optimization in patients with cardiovascular disease. The major technical development is a new interleaved-frequency, time-resolved MRI pulse sequence that can provide robust and reliable measurements of cardiac metabolic signals. The technique was applied to several realistic pre-clinical models of cardiac disease and the work presented will hopefully lead towards significant improvement in the management of patients with heart failure.
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Tungjitkusolmun, Supan. "Finite element modeling of radio-frequency cardiac and hepatic ablation /." 2000. http://www.library.wisc.edu/databases/connect/dissertations.html.
Повний текст джерела
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Antunes, Eduardo José Pereira. "Cardiac morphological changes induced by low-frequency noise in rats." Tese, 2013. https://repositorio-aberto.up.pt/handle/10216/69812.
Повний текст джерела
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Antunes, Eduardo José Pereira. "Cardiac morphological changes induced by low-frequency noise in rats." Doctoral thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/69812.
Повний текст джерела
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Bishay, Rami. "High-frequency ultrasound assessment of cardiac graft rejection in heterotopically transplanted mice." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=453010&T=F.
Повний текст джерела
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Hung, Chung-Lieh, and 洪崇烈. "The association between alcohol use frequency, dose, and cardiac structure and function." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/d56e58.
Повний текст джерелаАнотація:
博士國立陽明大學
臨床醫學研究所
105
Background and Objectives: Chronic excessive alcohol consumption may cause detrimental effects on cardiac structure and function. Evidence of preclinical LV and left atrial (LA) functional alterations in alcohol consumers prior to the development of overt heart failure or AF may be clinically important based on the view point of primary preventive medicine, especially for light to moderate users. Method: We consecutively studied 3,946 asymptomatic participants (mean age: 49.9 years, 35% female) from an ongoing cardiovascular health screening program at a tertiary medical center in Northern Taipei, Taiwan. Tissue Doppler Imaging (TDI), left ventricular (LV) strain (S) and left atrial (LA) strain (S), strain rate (SR) were all measured by echocardiography. Study participants were categorized based on graded alcohol consumption on a weekly basis: 1) Group A Non-drinkers: non-users or <1 drink/week, n=3,464; 2) Group B Light drinkers: 1-6 drinks/week, n=323; 3) Group C Moderate drinkers: >6 drinks/week, n=89; and 4) Group D Past drinkers (n=70). ANOVA with post hoc paired comparisons and multivariate regression models between dosage of alcohol consumption and LA/LV structural/mechanical changes were examined. Experimental animal model was conducted by randomizing male 4-month-old C57BL/6 mice into one of three groups: 1) liquid diet (control group [Ctrl]; or either a 2) 4% or 3) 6% alcohol liquid diet as their only fluid and food source for continuous 14 weeks. Immunoconfocal imaging and Western immunoblotting analysis were performed to examine the myocardial tissue changes, with echocardiography and optical mapping used to assess altered cardiac structure/function and cardiac electrical conduction activation sequence and pattern. Main Findings: 1. Larger LV dimension, wall thickness, increasing LA volumes, greater LV mass index, as well as more prolonged deceleration time (DT), isovolumic relaxation time (IVRT) and lower’ relaxation E’ with relatively unchanged LV ejection fraction (LVEF) (p: 0.345) were observed across 3 alcohol consumption groups (ANOVA p<0.001). Significant reduction of TDI-based myocardial contraction velocity S’was also observed (p: 0.0092); 2. A markedly worsened longitudinal systolic function in terms of lower averaged LV longitudinal strain (GLS) was observed (-18.32±2.29% vs -18.11±2.3%/-17.94±2.39%) in Non- vs Light/ Moderate drinkers (ANOVA p<0.001) (Coef: 0.25 [95% CI: 0.05 to 0.45] and 0.55 [95% CI: 0.17 to 0.92] with Non-Drinkers as reference group in multivariate models), which were accompanied by significant, graded reduction of LA strain (S) and LA diastolic strain rate (SRe) across 3 alcohol categories (all p<0.05). In general, worse GLS, LAS, SRe and SRs were observed in light-moderate drinkers compared to non-drinkers (all p<0.001), which followed a dose-response relationship. Finally, these differences did not change after careful 2:1 propensity-matching (n=760 for non- v.s. n=380 for light-moderate drinkers [n=307 and 73 for Light and Moderate Drinkers, respectively]); 3. In our experimental animal model, chronic alcohol-fed C57BL/6 mice, especially 6% mice, demonstrated substantially increased ventricular collagen I depots and fibrotic turnover, elicited macrophage infiltration of myocardium and contractile dysfunction. A specific perturbed and disturbed pattern and lower ventricular propagation velocity in both 4 and 6% alcohol mice groups were observed by optimal mapping (p<0.05). Down-regulated (nearly 50%), remodeled Cx43 together with clustered and diminished ordered membrane Nav1.5 distribution were also observed in mice feeding with alcohol diet, which in conjunction with increased cardiac fibrosis may explain the observed myocardial electromechanical dysfunctions. Conclusions: Our findings suggest that habitual alcohol consumption, even at relatively low weekly doses, may be associated with detrimental effects on atrial and ventricular functions in a dose-response fashion independent of other clinical factors or life styles. Our animal model supported mechanistic insights into the pathological understanding of these electromechanical functional alterations at a cellular and molecular level.
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Kahlbau, Ana Maria Pereira Alves Lousinha. "New observations on cardiac morphological changes induced by low-frequency noise and infrasound in rats." Tese, 2020. https://hdl.handle.net/10216/127509.
Повний текст джерела
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Kahlbau, Ana Maria Pereira Alves Lousinha. "New observations on cardiac morphological changes induced by low-frequency noise and infrasound in rats." Doctoral thesis, 2020. https://hdl.handle.net/10216/127509.
Повний текст джерела
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Beggs, Clive B., Simon J. Shepherd, and Kevin G. Kerr. "Increasing the frequency of hand washing by healthcare workers does not lead to commensurate reductions in staphylococcal infection in a hospital ward." 2008. http://hdl.handle.net/10454/584.
Повний текст джерелаАнотація:
Hand hygiene is generally considered to be the most important measure that can be applied to prevent the spread of healthcare-associated infection (HAI). Continuous emphasis on this intervention has lead to the widespread opinion that HAI rates can be greatly reduced by increased hand hygiene compliance alone. However, this assumes that the effectiveness of hand hygiene is not constrained by other factors and that improved compliance in excess of a given level, in itself, will result in a commensurate reduction in the incidence of HAI. However, several researchers have found the law of diminishing returns to apply to hand hygiene, with the greatest benefits occurring in the first 20% or so of compliance, and others have demonstrated that poor cohorting of nursing staff profoundly influences the effectiveness of hand hygiene measures. Collectively, these findings raise intriguing questions about the extent to which increasing compliance alone can further reduce rates of HAI.
In order to investigate these issues further, we constructed a deterministic Ross-Macdonald model and applied it to a hypothetical general medical ward. In this model the transmission of staphylococcal infection was assumed to occur after contact with the transiently colonized hands of HCWs, who, in turn, acquire contamination only by touching colonized patients. The aim of the study was to evaluate the impact of imperfect hand cleansing on the transmission of staphylococcal infection and to identify, whether there is a limit, above which further hand hygiene compliance is unlikely to be of benefit.
The model demonstrated that if transmission is solely via the hands of HCWs, it should, under most circumstances, be possible to prevent outbreaks of staphylococcal infection from occurring at a hand cleansing frequencies <50%, even with imperfect hand hygiene. The analysis also indicated that the relationship between hand cleansing efficacy and frequency is not linear - as efficacy decreases, so the hand cleansing frequency required to ensure R0<1 increases disproportionately.
Although our study confirmed hand hygiene to be an effective control measure, it demonstrated that the law of diminishing returns applies, with the greatest benefit derived from the first 20% or so of compliance. Indeed, our analysis suggests that there is little benefit to be accrued from very high levels of hand cleansing and that in most situations compliance >40% should be enough to prevent outbreaks of staphylococcal infection occurring, if transmission is solely via the hands of HCWs. Furthermore we identified a non-linear relationship between hand cleansing efficacy and frequency, suggesting that it is important to maximise the efficacy of the hand cleansing process.
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Krishna, Abhilash. "Multiphysics model of a cardiac myocyte: A voltage-clamp study." Thesis, 2012. http://hdl.handle.net/1911/71664.
Повний текст джерелаАнотація:
We develop a composite multiphysics model of excitation-contraction coupling for a rat ventricular myocyte under voltage clamp (VC) conditions to: (1) probe mechanisms underlying the response to Ca2+-perturbation; (2) investigate the factors influencing its electromechanical response; and (3) examine its rate-dependent behavior (particularly the force-frequency response (FFR)). Motivation for the study was to pinpoint key control variables influencing calcium-induced calcium-release (CICR) and examine its role in the context of a physiological control system regulating cytosolic Ca2+ concentration and hence the cardiac contractile response.
Our cell model consists of an electrical-equivalent model for the cell membrane and a fluid-compartment model describing the flux of ionic species between the extracellular and several intracellular compartments. The model incorporates frequency-dependent calmodulin (CaM) mediated spatially heterogenous interaction of calcineurin (CaN) and Ca2+/calmodulin-dependent protein kinase-II (CaMKII) with their principal targets and accounts for rate-dependent, cyclic adenosine monophosphate (cAMP)-mediated up-regulation. We also incorporate a biophysical model for cardiac contractile mechanics to study the factors influencing force response.
The model reproduces measured VC data published by several laboratories, and generates graded Ca2+-release with high Ca2+ gain by achieving negative feedback control and Ca2+-homeostasis. We examine the dependence of cellular contractile response on: (1) the amount of activator Ca2+ available; (2) the type of mechanical load applied; (3) temperature (22 to 38ºC); and (4) myofilament Ca2+ sensitivity. We demonstrate contraction-relaxation coupling over a wide range of physiological perturbations. Our model reproduces positive peak FFR observed in rat ventricular myocytes and provides quantitative insight into the underlying rate-dependence of CICR.
The role of Ca2+ regulating mechanisms are examined in handling induced Ca2+-perturbations using a rigorous cellular Ca2+ balance. Extensive testing of the composite model elucidates the importance of various direct and indirect modulatory influences on the cellular twitch-response with wide agreement with measured data on all accounts. We identify cAMP-mediated stimulation, and rate-dependent CaMKII-mediated up-regulation of Ca2+-trigger current (ICaL) as the key mechanisms underlying the aforementioned positive FFR. Our model provides biophysically-based explanations of phenomena associated with CICR and provides mechanistic insights into whole-cell responses to a wide variety of testing approaches used in studies of cardiac myofilament contractility.
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Makedonov, Ilia. "Investigation of the Effects of Aging and Small Vessel Disease on Cardiac Frequency Signal in Cerebral White Matter as Imaged by Echo Planar Imaging using Magnetic Resonance." Thesis, 2012. http://hdl.handle.net/1807/32259.
Повний текст джерелаАнотація:
Cerebral small vessel disease (SVD) is highly prevalent in older adults and is a predictor of stroke, dementia, and death. SVD is also associated with cognitive dysfunction, gait problems, and urinary incontinence. SVD is diagnosed based on white matter hyperintensities on T2
weighted scans. This thesis investigates the cardiac frequency component of resting state
functional magnetic resonance imaging data in young healthy adults, older healthy adults, and older adults with pronounced SVD. A cardiac pulsatility metric is defined, and a tissue type contrast is observed between white matter, grey matter, and cerebrospinal fluid. Aging and disease effects are observed on cardiac pulsatility in white matter. The increased pulsatility may reflect the pathology of venous collagenosis and draining vein stenosis. Developing a better understanding of the etiology of SVD is an important step towards treating the disease.
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Bola, Mariana Gomes. "Avaliação e prescrição de exercício. Caracterização da intensidade da Modalidade de Spinning." Master's thesis, 2018. http://hdl.handle.net/10400.5/19301.
Повний текст джерелаАнотація:
O presente relatório foi realizado para adquirir o título de Mestre em Exercício e Saúde da Faculdade de Motricidade Humana e traduz o trabalho realizado e o conhecimento adquirido ao longo de um ano letivo de estágio como fisiologista do exercício em Doenças Crónicas e Gestão do Peso, em contexto de ginásio, no Ginásio Clube Português (GCP).
Na primeira parte do relatório, foi efetuado o enquadramento teórico da prática profissional, sistematizando informações sobre o individuo aparentemente saudável, com doença cardiovascular e com excesso de peso e obesidade. Descreve-se ainda para os mesmos indivíduos, a importância e benefícios do exercício físico e a prescrição do mesmo.
Na segunda parte, foram descritas as experiências vividas neste local de estágio e todas as intervenções no mesmo, as razões que me moveram na escolha da instituição, todas as tarefas realizadas na mesma, os principais obstáculos ao longo do estágio, e o contributo feito no ginásio – Comportamento da Frequência Cardíaca nas aulas de Spinning.
No final, realiza-se uma reflexão sobre o percurso realizado ao longo do presente ano letivo, salientando objetivos concretizados, objetivos não concretizados e dificuldades sentidas.The present report was developed in order to achieve the title of Master in Exercise and Health from Faculdade de Motricidade Humana and reflects the work developed and the knowledge acquired during one academic year of internship as exercise physiologist in chronic diseases and weight management, in gym context, at Ginásio Clube Português (GCP). In the first section of the report, it was developed a theoretical framework of the professional practice, systematising informations regarding an apparently healthy, with cardiovascular disease and over weighted with obesity individual. It is also described for the same individual, the importance and the benefits of physical exercise and its prescription. In the second section, there is a description of the experience lived within the internship local and all the interventions made, the reasons that moved me in choosing this institution, all the tasks performed, the main obstacles along the internship and the contributions made to the gym – behaviour of cardiac frequency in Spinning classes. At the end, a reflection regarding the path made along the present academic year, highlighting the objectives achieved and not achieved and the difficulties felt is made.