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This thesis proposes the use of Machine Learning (ML) to two very distinct, yet compelling, applications – predicting cardiac arrhythmia episodes and predicting base station association in 5G networks comprising of virtual cells. In the first scenario, Support Vector Machines (SVMs) are used to classify features extracted from electrocardiogram (EKG) signals. The second problem requires a different formulation departing from traditional ML classification where the objective is to partition feature space into constituent class regions. Instead, the intention here is to identify temporal patterns in unequal-length sequences. Using Recurrent Neural Networks (RNNs), it is demonstrated that accurate predictions can be made as to the base station most likely to provide connectivity for a mobile device as it moves. Atrial Fibrillation (AF) is a common cardiac arrhythmia affecting several million people in the United States. It is a condition in which the upper chambers of the heart are unable to contract effectively leading to inhibited blood flow to the ventricles. The stagnation of blood is one of the major risk factors for stroke. The Computers in Cardiology Challenge 2001 was organized to further research into the prediction of episodes of AF. This research revisits the problem with some modifications. Patient-specific classifiers are developed for AF prediction using a different dataset and employing shorter EKG signal epochs. SVM classification yielded an average accuracy of just above 95% in identifying EKG epochs appearing just prior to fibrillatory rhythms. 5G cellular networks were envisaged to provide enhanced data rates for mobile broadband, support low-latency communication, and enable the Internet of Things (IoT). Handovers contribute to latency as mobile devices are switched between base stations due to movements. Given that customers may not be willing to continuously share their exact locations due to privacy concerns and the establishment of a mobile network architecture with dynamically created virtual cells, this research presents a solution for proactive mobility management using RNNs. A RNN is trained to identify patterns in variable-length sequences of Received Signal Strength (RSS) values, where a mobile device is permitted to connect to more than a single base station at a time. A classification accuracy of over 98% was achieved in a simulation model that was set up emulating an urban environment.

Abstract Atrial fibrillation (AF) is a common arrhythmia in the clinical setting with a population prevalence of 1–2%. AF significantly increases the risk of stroke and death, worsens coexistent heart diseases and may leave the patient with disabling symptoms. The treatment of AF consists of the control of the underlying conditions, prevention of complications and symptom relief by controlling heart rate (rate control) or by targeting normal rhythm (rhythm control), with the latter achieved either by antiarrhythmic drug (AAD) therapy or catheter ablation (CA). Ablation therapy has generally been applied and studied after failure of AAD therapy. The aim of this study was to evaluate the safety and efficacy of first-line CA in AF. The other objectives were to assess the safety of continuous warfarin therapy during CA and to identify prognostic markers for treatment outcome. A meta-analysis of all randomised studies and a secondary analysis of one randomised study comparing CA and AAD as first-line therapy were performed. In the first study, ablation therapy reduced AF recurrences more than AAD therapy (HR 0.63) when provided as first-line therapy; the rate of complications was similar with both therapies. Some of the complications of ablation therapy were more serious than those encountered with AADs. The second study revealed that the antiarrhythmic efficacy of ablation therapy was more durable. In the third study, the efficacies of continuous and interrupted warfarin therapy were compared in 228 procedures; both strategies were found to be equally safe during a three month follow-up. Furthermore, an analysis of 2317 AF episodes revealed a new electrocardiographic feature at AF initiation, which was associated with AF relapse after the initiation of therapy. Finally, a thorough echocardiographic examination was performed in 49 patients prior to ablation therapy. Mild diastolic dysfunction was associated with AF recurrence. In conclusion, CA was more effective as a first-line therapy than AADs but may cause more severe complications. Continuous warfarin therapy was found to be safe during CA. New electrocardiographic and echocardiographic markers for treatment outcome were recognised. / Tiivistelmä Eteisvärinä on yleinen rytmihäiriö, jonka esiintyvyys väestössä on 1–2 % luokkaa. Eteisvärinä lisää merkittävästi kuolleisuutta ja aivoinfarktiriskiä, vaikeuttaa muiden sydänsairauksien oireita ja saattaa aiheuttaa invalidisoivia oireita. Eteisvärinän hoito keskittyy liitännäissairauksien hoitoon ja komplikaatioiden estoon sekä oireiden lievitykseen joko syketaajuutta säätämällä (sykkeenhallinta) tai pyrkimällä normaaliin rytmiin (rytminhallinta). Rytminhallinnassa käytetään yleisesti joko rytmihäiriölääkkeitä tai katetriablaatiohoitoa. Eteisvärinän katetriablaatiota on useimmiten käytetty ja tutkittu tilanteessa, jossa rytmihäiriölääkitys on osoittautunut tehottomaksi. Tämän tutkimuksen tavoitteena oli arvioida eteisvärinän katetriablaatiohoidon tehoa ja turvallisuutta ensilinjan hoitona. Muina tavoitteina oli katetriablaation turvallisuuden arviointi jatkuvan varfariinihoidon aikana sekä löytää uusia katetriablaatiohoidon tehoa ennustavia tekijöitä. Teimme meta-analyysin kaikista randomisoiduista tutkimuksista ja sekundaarisen analyysin yhdestä randomisoidusta tutkimuksesta, jotka vertasivat rytmihäiriölääke- ja katetriablaatiohoitoa ensilinjan hoitona. Ensimmäisessä työssä ablaatiohoito esti eteisvärinän uusiutumista tehokkaammin (riskisuhde 0.63), eikä komplikaatioiden yleisyydessä ollut eroa hoitojen välillä. Jotkut ablaatiohoitoon liittyvät komplikaatiot olivat kuitenkin luonteeltaan vakavampia kuin lääkehoidossa. Ablaatiohoidon eteisvärinää estävä vaikutus todettiin pidempikestoiseksi toisessa työssämme. Kolmannessa työssä vertasimme jatkuvaa ja tauotettua varfariinihoitoa 228 ablaatiotoimenpiteen aikana. Molemmat lähestymistavat osoittautuivat yhtä turvallisiksi 3 kuukauden seuranta-aikana. Analysoimme edelleen 2317 eteisvärinäkohtausta ja löysimme osalla potilaista uuden eteisvärinäkohtauksen alkuun liittyvän ominaisuuden, joka oli yhteydessä rytminhallinnan tehottomuuteen. Lisäksi teimme 49 potilaalle laajan sydämen ultraäänitutkimuksen ennen katetriablaatiotoimenpidettä. Diastolisen dysfunktion havaittiin olevan yhteydessä eteisvärinän uusiutumiseen. Yhteenvetona totesimme että katetriablaatiohoito on rytmihäiriölääkehoitoa tehokkaampaa ensilinjan hoitona, mutta siihen mahdollisesti liittyvät komplikaatiot olivat luonteeltaan hankalampia. Jatkuva varfariinihoito todettiin turvalliseksi katetriablaation yhteydessä. Löysimme lisäksi sydänsähkökäyrästä ja sydämen ultraäänitutkimuksesta uusia hoidon tehoa ennustavia tekijöitä.

Background: Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia. There is a need for new pharmacological treatment strategies since the current antiarrhythmic drugs have a modest efficacy and may have severe side effects. Cardioversion (CV) of AF offers an opportunity to study related conditions in sinus rhythm (SR) and during AF. Since catheter ablation of AF is a symptomatic treatment, it is important to have tools for measurement of arrhythmia-related symptoms. Aims: To evaluate the effect of atorvastatin on maintaining SR after CV of persistent AF. To assess if highsensitivity C-reactive protein (hsCRP) predicts the recurrence of AF after CV in a population randomized to treatment with either atorvastatin or placebo. To quantify the symptomatic effect of left atrial catheter ablation of AF. To assess if the restoration of SR by CV, in a population with persistent AF, affects sleep apnea. Methods: Paper I: A total of 234 patients were randomized to treatment with either high dose atorvastatin or placebo prior to CV. Paper II: In a pre-specified substudy which included 128 of the patients in study I, hsCRP was analyzed before and after CV. Paper III: Umea 22 Arrhythmia Questions (U22) is a questionnaire that quantifies paroxysmal tachycardia symptoms. A total of 105 patients underwent first-time pulmonary vein isolation and answered U22 forms at baseline and follow-up 304 (SD 121) days after ablation. Paper IV: Polysomnography was performed before and after CV in 23 patients with persistent AF scheduled for elective CV. Results: Paper I: An intention-to-treat analysis with the available data, by randomization group, showed that 57 (51%) in the atorvastatin group and 47 (42%) in the placebo group were in SR 30 days after CV (OR 1.44, 95%CI 0.85–2.44, P=0.18). Paper II: HsCRP did not significantly predict recurrence of AF at 30 days. However, after adjusting for treatment with atorvastatin, hsCRP predicted the recurrence of AF (OR 1.14, 95% CI 1.01–1.27). Six months after CV, hsCRP at randomization predicted recurrence of AF in both univariate analysis (OR 1.30, 95% CI 1.06–1.60) and in multivariate logistic regression analysis (OR 1.33, 95% CI 1.06– 1.67). Paper III: The U22 scores for well-being, arrhythmia as cause for impaired well-being, derived timeaspect score for arrhythmia, and discomfort during attack detected relevant improvements of symptoms after the ablation. U22 showed larger improvement in patients undergoing only one procedure than in patients who later underwent repeated interventions. Paper IV: Obstructive sleep apnea occurred in 17/23 patients (74%), and central sleep apnea in 6/23 patients (26%). Five patients had both obstructive and central sleep apnea. SR at follow-up was achieved in 16 patients. The obstructive apnea-hypopnea index, central apneahypopnea index, and the number of patients with obstructive or central sleep apnea did not differ before and after restoration of SR. Conclusions: Atorvastatin is not a treatment option with regards to maintaining SR after CV in patients with persistent AF. HsCRP was associated with AF recurrence 1 and 6 months after successful CV of persistent AF. U22 quantifies the symptomatic improvement after AF ablation with adequate internal consistency and construct validity. Both obstructive and central sleep apneas are highly prevalent in patients with persistent AF. Obstructive sleep apneas are unaffected by the CV of AF to SR.

Orientadores: José Wilson Magalhães Bassani, Rosana Almada Bassani / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-18T15:44:00Z (GMT). No. of bitstreams: 1 Viana_MarcelodeAlmeida_M.pdf: 2859747 bytes, checksum: 35c1831b1c265e9788b9dcc01dfdbd47 (MD5) Previous issue date: 2011 / Resumo: A fibrilação ventricular (FV) é um tipo de arritmia cardíaca com alto potencial letal, cujo único tratamento eficaz conhecido é a desfibrilação elétrica, ou seja, aplicação de choques de alta intensidade. Este procedimento, no entanto, pode causar sério comprometimento da função cardíaca por afetar deleteriamente as células miocárdicas, o que pode resultar em insucesso da ressuscitação. Neste trabalho foi desenvolvida e testada uma instrumentação específica para o estudo de uma nova abordagem de desfibrilação elétrica cardíaca (estimulação multidirecional), que permitiu o chaveamento de choques sequenciais temporalmente defasados durante o mesmo ciclo estimulatório cardíaco, os quais foram aplicados a três pares de eletrodos em diferentes direções. A instrumentação foi testada in vivo, na desfibrilação direta do coração de suínos. A desfibrilação multidirecional permitiu uma redução em 20% da intensidade requerida dos choques, quando comparada à convencional (monodirecional) em uma ampla faixa de probabilidade de sucesso desfibrilatório. Mesmo para uma probabilidade de sucesso de 90%, os níveis de energia requeridos para a reversão da FV foram significativamente menores com a estimulação multidirecional (4,25 ± 0,63 J) do que com a estimulação monodirecional (5,09 ± 0,43 J, respectivamente; P< 0,05). Deste modo, a estimulação multidirecional demonstra ser uma importante inovação para permitir um tratamento desfibrilatório mais eficiente e seguro / Abstract: Ventricular fibrillation (VF) is a potentially lethal cardiac arrhythmia, for which the only known effective treatment is electrical defibrillation, i.e. application of high-intensity electric shocks to the heart. Such shocks, however, may exert deleterious effects on myocardial cells, which may impair cardiac function and result in resuscitation failure. In this work, a specific instrumentation was developed for the study of a new approach of cardiac defibrillation (multidirectional stimulation), in which shocks were switched and applied to three pairs of electrodes placed in different directions. The instrumentation was tested in vivo for direct defibrillation of pig hearts. With multidirectional defibrillation, the shock intensity required for defibrillation was 20% lower compared to conventional (monodirectional) defibrillation for a wide range of successful defibrillation probability. Even for a probability as high as 90%, the energy levels required for VF reversal were significantly lower with multidirectional stimulation than with monodirectional stimulation (4.25 ± 0.63 ± J vs. 5.09 0.43 J, respectively; P < 0.05). Thus, multidirectional stimulation seems to be an important innovation toward a more efficient and safer defibrillation treatment. / Mestrado / Engenharia Biomedica / Mestre em Engenharia Elétrica

A fibrilação, atrial ou ventricular, é caracterizada por uma desorganização da atividade elétrica do músculo. O coração, que normalmente contrai-se globalmente, em uníssono e uniforme, durante a fibrilação contrai-se localmente em várias regiões, de modo descoordenado. Para estudar qualitativamente este fenômeno, é aqui proposto um novo modelo matemático, mais simples do que os demais existentes e que, principalmente, admite uma representação singela na forma de circuito elétrico equivalente. O modelo foi desenvolvido empiricamente, após estudo crítico dos modelos conhecidos, e após uma série de sucessivas tentativas, ajustes e correções. O modelo mostra-se eficaz na simulação dos fenômenos, que se traduzem em padrões espaciais e temporais das ondas de excitação normais e patológicas, propagando-se em uma grade de pontos que representa o tecido muscular. O trabalho aqui desenvolvido é a parte básica e essencial de um projeto em andamento no Departamento de Engenharia Elétrica da EESC-USP, que é a elaboração de uma rede elétrica ativa, tal que possa ser estudada utilizando recursos computacionais de simuladores usualmente aplicados em projetos de circuitos integrados / Atrial and ventricular fibrillation are characterized by a disorganized electrical activity of the cardiac muscle. While normal heart contracts uniformly as a whole, during fibrillation several small regions of the muscle contracts locally and uncoordinatedly. The present work introduces a new mathematical model for the qualitative study of fibrillation. The proposed model is simpler than other known models and, more importantly, it leads to a very simple electrical equivalent circuit of the excitable cell membrane. The final form of the model equations was established after a long process of trial runs and modifications. Simulation results using the new model are in accordance with those obtained using other (more complex) models found in the related literature. As usual, simulations are performed on a two-dimensional grid of points (representing a piece of heart tissue) where normal or pathological spatial and temporal wave patterns are produced. As a future work, the proposed model will be used as the building block of a large active electrical network representing the muscle tissue, in an integrated circuit simulator

Objetivo: Avaliar o uso de antitrombóticos em pacientes com fibrilação atrial (FA) em hospital cardiológico no Brasil (InCor).Métodos e resultados: Um estudo observacional transversal analisou os prontuários de todos os pacientes atendidos no InCor em cada um de 5 dias separados no ano de 2002 (Fase 1), sendo prospectivamente reanalisados após 1 ano (Fase 2). A prevalência da FA nos 3764 prontuários analisados foi de 8%. Antiplaquetários foram prescritos para 21,26% e 19,93%, anticoagulantes para 46,51% e 57,81%, e 32,23% e 22,26% não usavam nenhum antitrombótico nas Fases 1 e 2, respectivamente. Somente 15,60% e 23,25% apresentavam níveis de RNI terapêuticos.Conclusão: A anticoagulação é subutilizada nos pacientes com FA apesar do fato de serem tratados por cardiologistas em um hospital universitário / Objective: To assess antithrombotic therapy among atrial fibrillation (AF) patients in a Brazilian University Heart Hospital (InCor).Methods and results: A cross sectional study analyzed the charts of all patients treated at InCor in 5 separate days of 2002 (Phase 1), and prospectively reviewed them after one year (Phase 2). The prevalence of AF in the 3,764 assessed charts was of 8.0%. Antiplatelets were prescribed to 21.26% and 19.93%, anticoagulants to 46.51% and 57.81%, and 32.23% and 22.26% were not receiving any antithrombotic in Phases 1 and 2, respectively. Only 15.60% and 23.25% were within INR therapeutic range.Conclusion: Anticoagulation is underused in AF patients besides the fact of being treated by cardiologists in a University Hospital

Eventuais alterações no substrato anatômico miocárdico, no sistema nervoso autônomo (SNA) cardíaco intrínseco, envolvendo os plexos ganglionares (PG) comumente presentes em organizações de gordura epicárdicas denominadas fatpads (FP) ou a expressão dos receptores muscarínicos, poderiam ser responsáveis pela gênese e manutenção da fibrilação atrial (FA). Com o objetivo de analisar a relação entre fibrilação atrial permanente (FAP) e possíveis alterações anatômicas e micromorfológicas do coração, do SNA cardíaco intrínseco e da expressão dos receptores muscarínicos miocárdicos, foram estudados 13 corações de autópsias de portadores de FAP e cardiopatia crônica definida (grupo I) e 13 casos pareados pela mesma doença cardíaca, porém sem esta arritmia (grupo II). Foram analisados a anatomia da drenagem venosa do átrio esquerdo (AE), peso do coração, espessura do septo ventricular e diâmetro dos FP epicárdicos. Foram ressecadas duas amostras no átrio direito (AD1 e AD2), três no átrio esquerdo - no trajeto médio da VoAe (AE1), na junção da veia pulmonar superior esquerda (AE2) e na aurícula (AE3), três em FPs, atrial esquerdo superior (FP1), atrial direito posterior (FP 2) e no atrial esquerdo póstero-medial (FP 3) e uma amostra do septo ventricular (SIV), como controle. As alterações estruturais das fibras miocárdicas, as espessuras do epicárdio, endocárdio e miocárdio e o percentual de colágeno intersticial no miocárdio foram analisados através de histomorfometria computadorizada sob coloração de tricrômio de Masson. O SNA cardíaco intrínseco foi analisado através imuno-histoquímica para S-100 e tirosina-hidroxilase quanto a: quantidade e área das fibras nervosas, quantidade e área média de fibras simpáticas, quantidade e área média de fibras parassimpáticas e proporção de fibras simpáticas/parassimpáticas. A expressão miocárdica dos receptores muscarínicos 1 a 5 (M1 a M5) foi avaliada pela proporção positiva no miocárdio nos cortes AD1, AE1, AE2 e FP1. Não houve diferenças entre os grupos quanto às variáveis anatômicas e ao percentual de colágeno intersticial. A análise do SNA revelou fibras nervosas com menor área no grupo I, redução do número de fibras nervosas totais e parassimpáticas nos cortes AD1 e SIV, aumento de fibras totais e parassimpáticas AE2 e FP2 e aumento do número de fibras simpáticas nos cortes AD2, AE1, AE2 e AE3. Quanto à expressão dos receptores muscarínicos, houve aumento significante na porcentagem positiva para M1 em todas as regiões, exceto na AE1 (média de todos os cortes, grupo I 5,84 e grupo II 2,92, p=0,002); o M2 e M3 apenas junto ao FP1 (M2 grupo I 5,67 e grupo II 3,63, p=0,037; M3 grupo I 30,95 e grupo II 20,13, p=0,026) e o M4 foi aumentado no grupo I na região AE1 (grupo I 9,90 e grupo II 4,45, p=0,023); não houve alteração estatisticamente significante no M5. A anatomia e a disposição das fibras musculares atriais, bem como a fibrose intersticial não parecem estar relacionadas à FAP nos grupos estudados. Alterações no número de fibras nervosas bem como e alterações na expressão dos receptores muscarínicos atriais, especialmente o M1, particularmente em regiões próximas aos PG, parecem estar relacionadas à FAP, indicando a importância da modulação autonômica nesta arritmia / Possible changes in myocardial substrate, in the intrinsic cardiac autonomic nervous system (ANS), involving the ganglionated plexus (GP) present in fat-pads (FP) or the expression of muscarinic receptors could be responsible for the genesis and maintenance of atrial fibrillation (AF). Aiming to analyze the relationship between permanent atrial fibrillation (pAF) and possible anatomical and micromorphological heart changes, intrinsic cardiac ANS and expression of myocardial muscarinic receptors, 13 hearts from autopsies of patients with PAF and chronic heart disease (group I) were studied; and 13 cases matched by the same heart disease, but without this arrhythmia (group II). It was analyzed the anatomy of the venous drainage of the left atrium (LA), heart weight, ventricular septal thickness and diameter of epicardial FP. Two samples were taken in the right atrium (RA1 and RA2), three in the left atrium - in the middle portion of the left atrium oblique vein (LaOv LA1), at the junction of left superior pulmonary vein (LA2) and in the auricle (LA3), three FPs, left atrial superior (FP 1), right atrial posterior (FP 2) and the left atrial posteromedial (FP 3) and one sample of the ventricular septum (VS), as control. The structural changes of the myocardial fibers, thickness of the epicardium, endocardium and myocardium, and the percentage of interstitial collagen in the myocardium were analyzed by computerized histomorphometry on Masson trichrome staining. The intrinsic cardiac ANS was analyzed through immunohistochemistry for S-100 and tyrosine hydroxylase regarding the: amount and area of nerve fibers, amount and average area of sympathetic fibers, number and average area of parasympathetic fibers and sympathetic/parasympathetic fiber proportion. The myocardial expression of muscarinic receptors 1-5 (M1 to M5) was evaluated by positive ratio in the myocardium in sections RA1, LA1, LA2 and FP1. There were no differences between groups regarding the anatomical variant and the percentage of interstitial collagen. Analysis of the ANS revealed nerve fibers with the smallest area in group I, reduction in the number of total and parasympathetic nerve fibers of sections RA1 and VS, increase of total and parasympathetic fibers LA2 and FP2 and increased numbers of sympathetic fibers in sections RA2, LA1, LA2 and LA3. Regarding the expression of muscarinic receptors, there was a significantly increase in the positive percentage for M1 in all regions except for LA1 (average of all the sections, group I 5.84 and group II 2.92, p = 0.002), M2 and M3 just adjacent to the FP1 (M2 Group I 5.67 and Group II 3.63, p = 0.037; M3 Group I 30.95 and Group II 20.13, p = 0.026) and the M4 was increased in group I in the region LA1 (group I 9.90 and group II 4.45, p = 0.023) and there was no statistically significant change in the M5. The anatomy and arrangement of atrial muscle fibers, as well as the interstitial fibrosis did not appear to be related to PAF in both studied groups. Changes in the number of nerve fibers as well as changes in expression of atrial muscarinic receptors, specially the M1, particularly in regions close to the GP appear to be related to pAF, indicating the importance of autonomic modulation in this arrhythmia

Introdução: Na última década, desde a descrição inicial da ablação das veias pulmonares, a ablação por cateter da fibrilação atrial (FA) tem evoluído consideravelmente em eficácia e segurança, consolidando-se como opção terapêutica em pacientes selecionados com FA. No entanto, a ablação da FA é um procedimento complexo e não isento de riscos. Ainda que seja uma complicação rara, o desenvolvimento de fístulas átrio-esofágicas (FAE) é a segunda complicação responsável por morte relacionada ao procedimento e responde por 16% dos casos de morte após ablação de FA. Consensos atuais não orientam recomendações definitivas para prevenção de lesões esofágicas, consideradas lesões precursoras de FAE. O objetivo deste trabalho foi comparar a incidência de lesões esofageanas e periesofageanas por ecoendoscopia após ablação de fibrilação atrial, utilizando diferentes estratégias de proteção esofágica durante as aplicações de radiofrequência na parede posterior do átrio esquerdo. Método: No período de outubro/2012 a julho/2014, foram estudados 45 pacientes submetidos à ablação percutânea de FA, portadores de FA paroxística ou persistente há menos de um ano. Todos os pacientes foram submetidos a ablação circunferencial com isolamento elétrico das veias pulmonares, com cateter de ablação 8 mm. Antes do procedimento, os pacientes foram randomizados para uma de três estratégias de proteção esofágica durante as aplicações de radiofrequência na parede posterior do átrio esquerdo para ablação da FA: Grupo I - aplicações limite fixo e de baixa energia, 30 W; Grupo II - aplicações com energia limitada pela temperatura esofágica; GIII - aplicações com limite fixo de energia durante resfriamento esofágico contínuo. A pesquisa de lesões esofágicas/periesofágicas foi feita por ecoendoscopia realizada em até 48 horas após a ablação. Resultados: As características basais foram similares nos três grupos, não sendo encontradas diferenças significativas entre as variáveis clínicas, laboratoriais, ecocardiográficas ou ecoendoscópicas prévias, com exceção da distância átrio-esofágica pré-ablação medida pela ecoendoscopia, que foi menor no Grupo III (GI = 3,9 mm +- 0,4; GII = 3,9 mm +- 0,5; GIII = 3,4 mm +- 0,4, p = 0.002). Nas ecoendoscopias pós-ablação de FA, foram encontradas 04 lesões esofágicas/periesofágicas: duas úlceras de parede esofágica e dois casos de edemas de mediastino periesofágico. Todos os casos de lesões esofágicas/periesofágicas ocorreram no grupo de resfriamento esofágico, G III (p= 0,008). A comparação das características clínicas dos pacientes que apresentaram lesões esofágicas/periesofágicas com os que não apresentaram essas alterações, pela análise bivariada, mostrou que foram similares nos dois grupos, exceto pelos valores médios de proteína C reativa (PCR) após a ablação de fibrilação atrial, que foram significativamente maiores no grupo com lesões (Grupo sem lesões: PCR = 0,82 mg/dl; Grupo com lesões: PCR = 2,12 mg/dl, p < 0,001). A comparação dos parâmetros das ablações por regiões das veias abordadas, quanto ao tempo das aplicações de radiofrequência, a potência e a temperatura do cateter de ablação, identificou que os pacientes que apresentaram lesões esofágicas/periesofágicas tiveram maiores valores de média de potência nas aplicações realizadas na parede posterior das veias pulmonares esquerdas, que os pacientes que não tiveram lesões (Grupo sem lesões esofágicas: potência média cateter = 37,7 w; Grupo com lesões esofágicas: potência média do cateter = 48,8 w, p = 0.013). A incidência de recorrência de arritmia após um único procedimento de ablação de Fibrilação Atrial, em seguimento clínico de 11 +- 5 meses, foi de 7 casos (15.6%), sem diferença significativa entre os grupos (GI = 26,7%, GII = 13,3% e GIII = 6,7%, p = 0,305). A incidência de complicações maiores relacionadas aos procedimentos de ablação realizados foi de 2,2% (um caso de congestão pulmonar no segundo dia após o procedimento, resolvido com uso de diuréticos). Conclusão: O uso da estratégia de resfriamento esofágico durante ablação de FA foi ineficaz como estratégia preventiva de lesões esofágicas/periesofágicas na população estudada, quando comparada às estratégias de aplicações de radiofrequência com baixa energia ou de energia limitada pela temperatura esofágica / Introduction: In the last decade, since the initial description of the ablation of pulmonary veins, the atrial fibrillation (AF) catheter ablation has evolved significantly in terms of efficacy and safety, consolidating itself as the therapeutic choice for AF selected patients. However, AF ablation is a complex procedure not without risks. Despite being a rare complication, the development of atrialesophageal fistulas (AEFs) ranks second in terms of procedure-related deaths, accounting for 16% of all post-AF ablation losses of life. Current consensus is not dispositive with regards to directives for the prevention of esophageal lesions, which come first and lead to AEFs. The objective of this work is to compare the incidence of esophageal and periesophageal lesions post-AF ablation, given use of different esophageal protection strategies during the radiofrequency applications on the left-atrium posterior wall. Method: From October 2012 through July 2014, 45 patients submitted to AF percutaneous ablation were studied. All of them were bearers of paroxistic or persistent AF for less than one year, and all of them were submitted to 8mm-catheter, pulmonary vein electric-shielding circumferential ablation. Before the procedure, patients were randomly assigned to one of three esophageal lesion protection strategies: Group I - 30w, low energy, fixed limited applications; Group II - energy applications limited by esophageal temperature; and Group III - fixed limit energy applications during continuous esophageal cooling. The survey for esophageal/periesophageal lesions was carried by means of esophageal endoscopy combined with radial ultrasound performed within 48 hours post ablation. Results: Baseline characteristics were even across groups; no significant differences in clinical, laboratorial, ecocardiographic or endoscopic variables were found, except for pre-ablation distance between posterior left atrium wall and the esophagus as measured by radial ultrasound endoscopic, smaller in Group III (GI = 3,9 mm +- 0,4; GII = 3,9 mm +- 0,5; GIII = 3,4 mm +- 0,4, p = 0.002). Post FA-ablation endoscopies revealed the existence of 4 counts of esophageal/periesophageal lesions: 2 esophageal wall ulcer and 2 periesophageal mediastin edema. All cases of esophageal/periesophageal lesions occurred in the esophageal cooling group (GIII) (p=0.008). Bivariate analysis on the clinical characteristics of patients that presented esophageal/periesophageal lesions showed no significant difference from those in the lesion-free group, except for average values for post ablation reactive-C protein (RCP), significantly greater in the lesion group (2.12 mg/dl vs. 0.82 mg/dl for the lesion-free group, p < 0.001). Ablation parameter comparison by approached vein region revealed that patients with post ablation lesions had received higher-powered applications in their posterior wall left pulmonary veins (average catheter power = 48.8 w vs. 37.7 w for lesion-free group, p=0.013). After a 11 +- 5 month clinical following, arrhythmia recurrence post a single AF ablation procedure added to 7 cases (15.6%), and no significant difference among the three different groups was found (GI = 26.7%, GII = 13.3% e GIII = 6.7%, p = 0.305). Incidence of major complications related to the ablation procedures reached 2.2% (one case of pulmonary congestion occurring in the second day post procedure, and resolved with the use of diuretics). Conclusion: The use of esophageal cooling during AF ablation was an ineffective strategy to prevent esophageal/periesophageal lesions in the studied population when compared to low-energy radiofrequency or energy limited by esophageal temperature lesion prevention strategies

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