Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (Ph.D.)--Bioengineering, Georgia Institute of Technology, 2007. / Committee Co-Chair: Litt, Brian; Committee Co-Chair: Vachtsevanos, George; Committee Member: Butera, Robert; Committee Member: Frazier, Bruno; Committee Member: Gerstenfeld, Edward; Committee Member: Hunt, William.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2010. / Härtill 5 uppsatser.

Atrial arrhythmias are the most prevalent sustained cardiac arrhythmias. Rates of hospitalisation and costs incurred to healthcare organisations are increasing in epidemic proportions. Despite this, the mechanisms of the transition from sinus rhythm to arrhythmic states are not well understood. The high level of regional electrical heterogeneity observed in the atria is thought to contribute towards the high prevalence of atrial arrhythmias. However, current computer models of the intact human atria only account for a small degree of this regional electrical heterogeneity, and do not include descriptions of the pacemaker regions of the sinoatrial node and the atrioventricular node. In this project, a new computational model of the intact 3D human atria is developed. First, a new single cell model to simulate the electrical action potential of the human atrial myocyte is developed. This model more accurately simulated the experimentally observed properties of human atrial action potentials than previous models. A family of electrically heterogeneous models describing the major regions within the atria is then developed, including those of the sinoatrial- and atrioventricular- nodes. This set of regional cell models represents the most expansive and complete set currently available. It is demonstrated that the large range of different electrical properties results in a large range of action potential morphology and duration within the atria. Models of the effect of sympathetic and parasympathetic regulation on the electrical AP of the models of the atrial working myocardium and the pacemaker regions were also incorporated. This demonstrated that sympathetic regulation can increase the pacing rate of the sinoatrial node and the atrio-ventricular node, and has a complex dose dependent effect on the atrial working myocardium. Four distinct models of the effects of atrial fibrillation induced remodelling on the atrial working myocardium are developed. These characterised the effect of remodelling of IKur on the overall changes in action potential morphology and duration observed. It is shown that the presence or absence of remodelling of this channel accounts for two distinct observed morphologies. A previous 3D anatomical model of the human atria is improved. First, detailed anatomical models for the sinoatrial node and the atrioventricular node are incorporated into the model. Second, it is further segmented to include regions for the pulmonary veins, atrio-ventricular ring, atrial septum and sinoatrial node block zone. This model is used to investigate the effects of sympathetic and parasympathetic regulation in the 3D atria. Finally, a detailed investigation of the underlying mechanisms of atrial fibrillation in the 3D atria, and the effect of electrical remodelling on the behaviour of atrial fibrillation, is performed using the detailed 3D model. This work represents a significant advance in 3D human atrial modelling. The anatomical model incorporates a greater level of complexity than previous models, and for the first time allowed investigation of the pacemaking mechanisms in the 3D intact human atria. The atrial fibrillation protocols are more physiologically relevant than previous models and have elucidated the roles that electrophysiological remodelling, electrical heterogeneity and structural anisotropy play in the development and maintenance of atrial fibrillation.

Introduction: Atrial fibrillation is the most common sustained arrhythmia. The quality of atrial fibrillation treatment in clinical practice varies between hospitals and doctors. Due to the increasing prevalence of atrial fibrillation in the more elderly population, it might be difficult in the future to refer patients to a limited number of heart specialists. At the same time, a new generation of University educated nurses is growing, but, unfortunately, their competencies are as low as their colleagues' with high-school education. However, in some areas, such as diabetology or gastroenterology, specialist nurses, whose aim is to supplement medical doctors to some extent, are gradually occurring. In the Czech Republic, there are no specialist nurses in cardiology, even though they are quite common abroad. Our aim is to assess the feasibility of a specialist nurse for diagnosis and treatment of atrial fibrillation. Methods: Main inclusion criterion for our study was a diagnosis of atrial fibrillation made on one of the non-internal medicine wards or in the general practitioners' practice. An exclusion criterion was previous examination by one of the heart specialists either internal medicine doctor or a cardiologist. During the first interview, I checked previous investigations for the atrial fibrillation and the arrhythmia treatment. The questionnaire contained questions on demographic parameters and patients' knowledge about their disease and possible complications. Subsequently, I recorded my recommendations regarding further investigations and therapeutic possibilites. All patients were sent to a cardiologist as required by our national guidelines. The second interview was made over the phone 2 months later and comparison of the doctor's recommendations with my suggestions was made. During this interview, an assessment of the concept of a nurse specialist in atrial fibrillation was performed. Results: Forty patients with atrial fibrillation documented on an ECG were recruited. At a time of the first interview, only 10 patients (25%) had their echocardiogram performed and only 23 (57,5%) patients had their thyroid gland hormones checked. 26 (65%) patients were on anticoagulation medicine while CHADS2-Vasc score of 2 and more was documented in 34 (85%) patients. There was an agreement between doctor's and nurse's recommendations regarding missing investigations and anticoagulation treatment. However, no agreement was achieved in the area of arrhythmia treatment, which means that this should remain a doctor's responsibility. Patients were informed about possible complications in only 11 (27,5%) cases and about all therapeutic options in 2 (5%) cases. 29 (72,5%) patients would be interested in consulting a specialist nurse in the future, whereas 11 (27,5%) patients would prefer a doctor. Results: We managed to confirm that the novel concept of a specialist nurse for the diagnosis and treatment of atrial fibrillation is feasible. The specialist nurse is able to confirm the diagnosis, check the completeness of the investigations, educate patients and assess the risk of the thromboembolic disease. Competencies of the nurses should be extended, so this concept could be introduced into the clinical practice.

An integration of ICT advances into a conventional healthcare system is spreading extensively nowadays. This trend is known as Electronic health or E-Health. E-Health solutions help to achieve the sustainability goal of increasing the expected lifetime while improving the quality of life by providing a constant healthcare monitoring. Cardiovascular diseases are one of the main killers yearly causing approximately 17.7 million deaths worldwide. The focus of this work is on studying the detection of one of the cardiovascular diseases – Atrial Fibrillation (AF) arrhythmia.  This type of arrhythmia has a severe influence on the heart health conditions and could cause congestive heart failure (CHF), stroke, and even increase the risk of death. Therefore, it is important to detect AF as early as possible. In this thesis we focused on studying various machine learning techniques for AF detection using only short single lead Electrocardiography recordings. A web-based solution was built as a final prototype, which first simulates the reception of a recorded signal, conducts the preprocessing, makes a prediction of the AF presence, and visualizes the result. For the AF detection the relatively high accuracy score was achieved comparable to the one of the state-of-the-art. The work was based on the investigation of the proposed architectures and the usage of the database of signals from the 2017 PhysioNet/CinC Challenge. However, an additional constraint was introduced to the original problem formulation, since the idea of a future deployment on the resource-limited devices places the restrictions on the complexity of the computations being performed for achieving the prediction. Therefore, this constraint was considered during the development phase of the project.

The topic of my diploma thesis is: ?The Questions of the Care of Patients before and after the Intervention for Ventricular Fibrillation ?. The diploma thesis defines three objectives. The first objective finds out the information level of patients about nursing care before and after the intervention for ventricular fibrillation. The second objective was to find out the most frequent problems in connection with the intervention for ventricular fibrillation. The third objective aims at surveying the requirements for the nursing care in connection with the intervention for ventricular fibrillation. To conduct my research I defined 4 questions along with these objectives: Are patients informed about nursing care before and after the intervention for ventricular fibrillation? In which way do nurses inform patients about nursing care before and after the intervention for ventricular fibrillation? How do nurses assess the cooperation with patients before and after the intervention for ventricular fibrillation? In which fields are patients most limited after the intervention for ventricular fibrillation? To fulfil the objectives of the diploma thesis I chose the quantitative research survey. The collection of data was conducted by the interview technique. These interviews constituted the basis for the chart of ideas in the X-mind programme. The research questions that were defined for the research survey yielded these conclusions: The information on the regime before the radiofrequency ablation for fibrillation of chambers is insufficient for the patients. The information on the regime after the radiofrequency ablation for ventricular fibrillation is insufficient for the patients. Nurses inform patients about the nursing care before the performance based on nursing standards. The largest problem encountered by patients after the radiofrequency ablation for ventricular fibrillation is bowel movement. Patients before the radiofrequency ablation for ventricular fibrillation worry because of lack of information about the performance. The patients before the radiofrequency ablation for ventricular fibrillation cooperate with the nursing staffs. The patients after the radiofrequency ablation for ventricular fibrillation cooperate with the nursing staffs.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-06-27T12:24:48Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese _Sandro Vagner de Lima.pdf: 6041788 bytes, checksum: 30432ac952cb4559dfe9e27b22cd9bf5 (MD5) / Made available in DSpace on 2016-06-27T12:24:49Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese _Sandro Vagner de Lima.pdf: 6041788 bytes, checksum: 30432ac952cb4559dfe9e27b22cd9bf5 (MD5) Previous issue date: 2015-10-08 / Esta tese de doutorado foi dedicada à investigação do modo como a técnica de espectroscopia de impedância elétrica (EIE) poderia ser usada para acompanhar os processos de mudanças conformacionais de macromoléculas biológicas, como proteínas e DNA. Para isso, usamos como sistemas modelos a proteína albumina do soro bovino (BSA), e a formação do complexo polianilina/DNA (PANI/DNA). Com a caracterização de soluções de DNA e BSA por EIE e sua modelagem elétrica convenientemente descrita pelo circuito de Randles (e sua variante), foram determinados os parâmetros relevantes para descrição dos fenômenos de desnaturação e de agregação da proteína e da precipitação do complexo PANI/DNA. As informações obtidas sobre a solubilidade desses últimos complexos são de grande utilidade para o entendimento dos mecanismos de interação entre cadeias de DNA e de polímeros condutores. Do mesmo ponto de vista da EIE, as sucessivas mudanças da conformação da proteína e os detalhes da cinética de sua agregação na interação com surfactantes foram adequadamente correlacionados com a característica elétrica do circuito de Randles das soluções correspondentes. Finalmente, estudos iniciais foram estendidos para a análise dos processos de fibrilação de proteínas. Para todos os problemas abordados, o uso da resistência de transferência de carga elétrica (RCT) (um parâmetro do circuito de Randles) nos permite sugerir ser a técnica de EIE apropriada para caracterizar as diferentes mudanças conformacionais envolvidas em fenômenos que resultam da interação de biomoléculas com moléculas de prova. Assim, ela se confirma como um método competitivo quando comparado ao uso da fluorescência e da absorção UV-Vis (técnicas rotineiramente adotadas para a análise desses problemas). / This doctoral thesis was devoted to the investigation of the technique of electrical impedance spectroscopy as an alternative method to assess conformational changes of biological macromolecules, such as proteins and DNA. For this, we used protein bovine serum albumin (BSA), and the formation of polyaniline (PANI)/DNA complexes as model systems. With the characterization of DNA and BSA solutions by Electrical Impedance Spectroscopy (EIS) and their electrical modeling conveniently described by the Randles circuit (and its variant), we determined the relevant characteristics of phenomena such as the denaturation and aggregation of proteins (BSA), and polymer/DNA complex formation (PANI/DNA). As a result of this approach we identified the existence of different interaction regimes between the chains of polyaniline and DNA molecules that are dependent on the concentration of PANI/DNA and the existence of equilibrium conditions which separate regions of precipitation/stability the PANI/DNA complex. Also from this point of view, the modes of interaction BSA / surfactants involved in the conformation changes well as typical stages associated with fibrillation kinetics were adequately correlated with the electric characteristic of the Randles circuit. In all studies carry out in this thesis, the analysis of the electric charge transfer resistance behavior (RCT) (a parameter of the Randles circuit) when confronted with the results obtained by standard techniques showed that the EIS presents reliable and some comparative advantages. These results allow us to provide an adequate and competitive alternative to conventional methods such as UV-Visible absorption, fluorescence and the use of probe molecules

Orientador: Sebastião Araujo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T01:38:54Z (GMT). No. of bitstreams: 1 Ovalle_CarlosCezarIvoSant'Ana_D.pdf: 918971 bytes, checksum: 7890aba34116748396efbad3ac6c01f5 (MD5) Previous issue date: 2011 / Resumo: Fundamento: O papel de vasopressores não-adrenérgicos na ressuscitação cardiopulmonar (RCP) permanece controverso. Objetivo: O objetivo do estudo foi avaliar a eficácia da terlipressina (TP) vs. adrenalina (ADR) em aumentar a pressão de perfusão coronariana (PPCor) e o retorno da circulação espontânea (RCE) na RCP em suínos. Métodos: Sob anestesia ketamina/tiopental, fibrilação ventricular foi induzida em 44 porcos fêmeas imaturos, permanecendo não-assistida por 10min, seguido de 2min de RCP-manual (100 compressões/10 ventilações/min com ar). Os animais foram então alocados em quatro grupos, recebendo: 1) ADR (45?g/kg); 2) salina-placebo (10mL); 3) TP (20?g/kg); 4) TP (20?g/kg) + ADR (45?g/kg). Desfibrilação foi realizada 2min apos, observando-se os animais sobreviventes por um período de 30min. ECG, PA sistêmica, PAD e PEtCO2 foram monitorados continuamente. Resultados: A TP não diferiu do placebo quanto aos efeitos na PPC, com baixas taxas de RCE em ambos os grupos (1/11 vs. 2/11; p=NS). A ADR aumentou a PPC de 13 ± 12 para 54 ± 15mmHg (p<0,0001), efeito similar a TP+ADR (de 21 ± 10 para 45 ± 13mmHg; p<0,0001), com altas taxas de RCE/sobreviventes em ambos os grupos (10/11 vs. 9/11, respectivamente). Entre os sobreviventes, maior PAM foi observada no grupo TP+ADR vs. ADR (105 ± 19mmHg vs. 76 ± 21mmHg; p=0,0157). Conclusões: ADR e TP+ADR foram efetivas para aumentar a PPC/RCE neste modelo experimental, mas a TP isolada não foi diferente do placebo. Contudo, nos animais sobreviventes do grupo TP+ADR observou-se uma maior estabilidade hemodinâmica após a RCE, sugerindo que a TP possa ser uma medicação útil no manuseio da hipotensão pós-RCP / Abstract: Background: The role of non-adrenergic vasopressors during cardiopulmonary resuscitation (CPR) remains controversial. Objective: The aim of the study was to compare the efficacy of terlipressin (TP) vs. adrenaline (ADR) to increase coronary perfusion pressure (CPP) and the return of spontaneous circulation (ROSC) during CPR in pigs. Methods: Under ketamine/thiopental anesthesia, ventricular fibrillation was induced in 44 immature female pigs remaining non-assisted for 10min, followed by 2min of manual closed-chest CPR (100 thoracic compressions and 10 ventilation/min with air). The animals were then randomized into four groups, receiving: 1) ADR (45?g/kg); 2) saline-placebo (10mL); 3) TP (20?g/kg); 4) TP (20?g/kg) + ADR (45?g/kg). Defibrillation was attempted 2min later. Surviving animals were observed during 30min. EKG, systemic AP, RA pressure and PEtCO2 were continuously recorded. Results: TP was not different from placebo regarding their effects on CPP, with low ROSC rates in both groups (1/11 vs. 2/11, respectively; p=NS). ADR increased CPP from 13 ± 12 to 54 ± 15mmHg (p<0.0001), similar to TP+ADR (from 21 ± 10 to 45 ± 13mmHg; p<0.0001), with high rates of ROSC/survival in both groups (10/11 vs. 9/11, respectively). Among surviving animals, a greater MAP was recorded in TP+ADR when compared with ADR (105 ± 19mmHg vs. 76 ± 21mmHg; p=0.0157). Conclusions: ADR and TP+ADR were highly effective to increase CPP and ROSC in this experimental CPR model, but TP alone was not different from placebo. Moreover, surviving animals in TP+ADR group showed greater hemodynamic stability after ROSC, suggesting that TP could be a potential useful drug for post-CPR hypotension/shock management / Doutorado / Fisiopatologia Cirúrgica / Doutor em Ciências

Introdução: O tromboembolismo é uma grave complicação da fibrilação atrial (FA), particularmente em pacientes que vão se submeter à cardioversão, química ou elétrica. Para reduzir esse risco, os pacientes submetem-se à anticoagulação clássica, que vem sendo praticada há várias décadas. Apesar desta abordagem, em pacientes plenamente anticoagulados, não se conhece a prevalência de trombo ou contraste espontâneo no átrio esquerdo (AE). Por essa razão, alguns autores sugerem a realização do ecotransesofágico (ECOTEE) para confirmar o sucesso do tratamento e reduzir o risco de complicações tromboembólicas após a reversão. Os objetivos deste estudo foram: a) avaliar a prevalência de trombos e contraste espontâneo ao ECOTEE em pacientes que vão ser submetidos à cardioversão sob regime de anticoagulação plena; b) avaliar a incidência de tromboembolismo até 30 dias após o procedimento; c) avaliar a influência das variáveis clínicas (doenças associadas) e do ECOTEE (tamanho e volume indexado do AE, fração de ejeção ventricular; velocidade de fluxo no apêndice atrial esquerdo), além do escore CHA2DS2VASc e níveis de pró-BNP plasmático sobre a formação de trombo/contraste espontâneo. Métodos: Foram incluídos 85 pacientes (62 homens; média de idade 61±12 anos) com FA não valvar com indicação para cardioversão. Todos receberam varfarina com controle da taxa de INR. Quando se considerava o paciente plenamente anticoagulado (INR ente 2 e 3 por três semanas consecutivas), era prescrito um fármaco antiarrítmico (propafenona, sotalol ou amiodarona) cuja escolha se baseou em critérios clínicos. Na ausência de normalização do ritmo, eram encaminhados para cardioversão elétrica (CVE). No dia da CVE, os pacientes submetiam-se ao ECOTEE cujo resultado só era conhecido no dia seguinte após a cardioversão. Os pacientes recebiam alta com anticoagulante e retornavam ao ambulatório após 30 dias quando realizavam outro ECOTEE. Resultados: Todos os pacientes foram cardiovertidos com INR na faixa terapêutica (2,9±0,7). A reversão com fármacos ocorreu em 9/85 pacientes (10,6%); 67/76 pacientes submeteram-se à CVE e, destes, 58/67 (86%) reverteram ao ritmo sinusal. O ECOTEE antes da CVE evidenciou trombo no AE em 8/85 pacientes (9,4%) e contraste espontâneo em 36/85 pacientes (42,3%). Nenhuma variável clínica, escore CHA2DS2VASc, níveis plasmáticos de pró-BNP ou variáveis ecocardiográficas identificou pacientes com maior probabilidade de apresentar trombo/contraste espontâneo no AE. Após 30 dias, houve normalização das variáveis do ECOTEE. Em 5/8 (62,5%) pacientes, os trombos desapareceram e surgiu em outros dois pacientes (2,3%). O contraste espontâneo desapareceu em 24/38 (63%) pacientes. Não houve registro de nenhum caso de tromboembolismo sistêmico em 30 dias. A taxa de recorrência de FA foi de 21%. Conclusões: a) trombo atrial/contraste espontâneo foi detectado em 9,4% da população e nenhuma variável clínica ou ecocardiográfica identificou pacientes de risco; b) houve melhora das variáveis do ECOTEE após a reversão ao ritmo sinusal; d) o sucesso global da cardioversão foi de 88% e a taxa de recorrência de FA de 21% em 30 dias; c) não houve registro de tromboembolismo sistêmico em 30 dias, em ritmo sinusal ou em FA. / Introduction: Thromboembolism is a serious complication of atrial fibrillation (AF), particularly in patients who will undergo chemical or electrical cardioversion. To reduce this risk patients receive classic anticoagulant therapy, which has been practiced for several decades. Despite this approach, it is not known the prevalence of thrombus or spontaneous contrast in the left atrium (LA) in patients fully anticoagulated. For this reason, some authors have recommended the transesophageal echocardiogram (TEECHO) to reduce the risk of thromboembolic complications after cardioversion. The objectives of this study were: a) to evaluate the prevalence of thrombus and spontaneous contrast by TEECHO in patients about to undergo cardioversion under full anticoagulation regime; b) evaluate the incidence of thromboembolism within 30 days after the procedure; c) evaluate the influence of clinical variables (associated diseases) and TEECHO parameters (LA size and LA indexed volume, ventricular ejection fraction, flow velocity in the left atrial appendage), CHA2DS2VASc score and plasma pro-BNP levels on thrombus/spontaneous contrast formation. Methods: We included 85 patients (62 men; mean age 61 ± 12 years) with non-valvular AF referred for cardioversion. All received warfarin with INR control. When considering the patient fully anticoagulated (INR in the range of 2 to 3 for three weeks) it was prescribed an anti-arrhythmic drug (propafenone, sotalol or amiodarone) whose choice was based on clinical criteria. In the absence of normal rhythm, patients were referred for electrical cardioversion (ECV). On the day of ECV, all patients were submitted to the ECOTEE whose result was known only the next day after cardioversion. The patients were discharged with anticoagulant and returned to the clinic after 30 days when another ECOTEE was performed. Results: All patients were cardioverted with INR in the therapeutic range (2.9±0.7). Sinus rhythm was restored with drugs in 9/85 patients (10.6%); 67/76 patients underwent ECV and 58/67 (86%) reverted to sinus rhythm. The TEECHO before cardioversion showed a thrombus in LA in 8/85 patients (9.4%) and spontaneous contrast in 36/85 patients (42.3%). No clinical variable, CHA2DS2VASc score, pro-BNP plasma levels or echocardiography variables identified patients with an increased likelihood of thrombus/spontaneous contrast in LA. After 30 days, there was normalization of TEECHO variables. In 5/8 (62.5%) patients thrombi disappeared and appeared in two patients (2.3%). Spontaneous contrast disappeared in 24/38 (63%) patients. There were no reports of any case of systemic thromboembolism in 30 days. The AF recurrence rate was 21%. Conclusions: a) LA thrombus/ spontaneous contrast were detected in 9.4% of the population and no clinical or echocardiography variable identified patients at risk; b) there was an improvement of TEECHO variables after reversion to sinus rhythm; d) the overall success of cardioversion was 88% and the AF recurrence rate was 21% in 30 days; c) there was no systemic thromboembolism in 30 days, in patients in sinus rhythm or AF.