Introduction: Radiofrequency ablation (RFA) is a popular method of treating unresectable liver tumours by the use of a high frequency, alternating electrical current that heats and destroys tumour cells. The size of the ablation is limited by localised charring of adjacent tissue that prevents further conduction of the radiofrequency current. In the clinical setting, this results in increased rates of local recurrence in tumours that are greater than 3 cm in diameter as multiple, overlapping ablations need to be performed to treat the one tumour. To overcome this problem, a modified form of RFA called Bimodal Electric Tissue Ablation (BETA) has been created. BETA adds a direct electrical current to the alternating radiofrequency current, thus establishing its bimodal character. When direct currents are used in biological tissues, water is transferred from anode to cathode by a process called electro-osmosis. By attaching the cathode to the radiofrequency electrode, water is attracted to the area thus preventing tissue desiccation and charring. The BETA circuit has been constructed and tested using a porcine model. The aims of the studies are to confirm that larger ablations can be produced with the BETA system and that it is safe to use in an animal model. Three studies have been performed to test these aims in porcine liver. Methods: The first study was designed to compare sizes of the ablation produced between standard RFA and the BETA circuit. This was followed by a long-term study to assess associated changes to liver function and pathological changes within the liver as well as identifying any other treatment related morbidity. The third study assessed the difference in ablation size and safety aspects when the positive electrode of the direct current circuitry was moved from small surface area under the skin to a large surface area on the skin. Results: Ablations with significantly larger diameters are created with the BETA circuit using a multi-tine needle (49.55 mm versus 27.78 mm, p<0.001). This finding was confirmed in the third experiment using a straight needle (25 mm versus 15.33 mm, p<0.001). Ablations produced by the BETA circuit induce coagulative necrosis within the treated liver and the injury heals by fibrosis in a manner similar to other thermal therapies. Significant rises in some serum liver enzymes are seen within 24 hours of treatment but these return to normal within 4 days. An electrolytic type injury can be produced at the site of the positive electrode. By increasing the surface area of this electrode, the risk of tissue damage is decreased but ablations are significantly smaller (18 mm versus 25 mm, p<0.001). Conclusions: The BETA circuit consistently produces significantly larger ablations than RFA. The treatment appears safe but positioning of the positive electrode of the direct current requires careful consideration. Injuries produced behave like other thermal therapies with coagulative necrosis followed by fibrotic healing. As larger ablations are consistently produced, it is hypothesised that with further refinements, tumours greater than 3 cm in diameter could be treated with lower rates of recurrence. / Thesis (M.S.) -- University of Adelaide, School of Medicine, 2008

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

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

INTRODUÇÃO: Os tumores renais pequenos e localizados são hoje diagnosticados mais frequentemente graças ao uso mais intenso dos métodos de imagem, o que favorece técnicas de tratamento menos traumáticas e igualmente eficazes. Dentre as técnicas minimamente invasivas, uma alternativa atraente é a radiofrequência (RF) por ser eficiente, de baixo custo e fácil aplicação. OBJETIVO: Avaliar métodos de aprimoramento da aplicação da RF para promover lesão celular renal de forma mais eficiente, obtendo lesões maiores, utilizando diferentes temperaturas e, em seguida, administrar drogas vasoativas para comparar o tamanho das lesões. Objetivou-se avaliar também se há remanescência de células viáveis na área abrangida pela lesão. MATERIAL E MÉTODO: O estudo foi realizado na Divisão de Clínica Urológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo entre janeiro de 2005 e dezembro de 2008. Inicialmente, 16 cães (Grupo A) foram submetidos a RF no parênquima renal com diferentes temperaturas: 80, 90 e 100 graus centígrados. Para comparar os resultados, foi analisado o tamanho das lesões nas diferentes temperaturas por medida da profundidade e da largura, correlacionadas com a impedância. Em seguida, usando a temperatura de 90 oC, 14 cães foram submetidos a RF com injeção dos dois diferentes agentes vasoativos: como vasoconstritor, a adrenalina (Grupo B), versus a prostaglandina E1 (Grupo C) como vasodilatador. Após 14 dias, os animais foram submetidos a nefrectomia para avaliação das lesões e a sacrifício. RESULTADOS: Houve diferença estatisticamente significante na profundidade (p < 0,001) e largura (p < 0,001) da lesão entre as três temperaturas (80, 90 e 100 oC), sendo que há um pico no tamanho das lesões renais na temperatura de 90 oC. Foi observada diferença estatisticamente significante da impedância entre as três temperaturas estudadas (p < 0,001), e se observou resultado mais favorável a 90 oC (menor impedância) e similar entre as temperaturas de 80 e 100 oC. A segunda etapa do estudo demonstrou que o uso da prostaglandina E1 resultou em lesões significativamente mais profundas e mais largas que o uso da adrenalina e também que a resistência tecidual foi menor com a prostaglandina E1. CONCLUSÕES: A temperatura de 90 oC foi mais eficiente para provocar destruição celular com a RF por produzir lesões mais extensas na largura e profundidade, quando comparada com as temperaturas de 80o e 100 oC (p < 0,001). A impedância também foi menor com 90 oC (p < 0,001). Observou-se que as lesões produzidas sem drogas não apresentaram diferença significante comparado com o uso de prostaglandina E1. Porém, o uso de adrenalina promoveu lesões menores (p < 0,001) quando comparada com os dois outros grupos. Não foram observadas células viáveis na análise microscópica dentro dos limites atingidos pela RF em ambos os experimentos / INTRODUCTION: Small, localized renal tumors are diagnosed more frequently nowadays due to the more intense use of imaging methods, which favor less traumatic but equally efficacious treatment techniques. Among the minimally invasive techniques, an attractive alternative is that of radiofrequency (RF), as it is efficient, and easily applicable. OBJECTIVE: To assess methods for the improvement of the application of RF, for the more efficient promotion of the renal cell lesion, to obtain larger lesions, making use of various temperatures and then administering vasoactive drugs to compare the size of the lesions produced, and also to assess the existence of remaining viable cells in the area affected by the lesion. MATERIAL AND METHOD: The study was undertaken at the Urological Clinical Division of the Hospital das Clínicas of the Medical School of the University of São Paulo, between January 2005 and December 2008. Initially, 16 dogs (Group A) underwent RF of the renal parenchyma at various temperatures: 80, 90 and 100 degrees centigrade. For the comparison of the results, the size of the lesions at the various temperatures was analyzed by the measurement of their depth and width, correlated with the impedance. Then, using a temperature of 90 oC, 14 dogs were submitted to RF with an injection of one of the two different vasoactive agents: adrenaline, vasoconstrictor (Group B), versus with E1 prostaglandin, vasodilator (Group C). After 14 days, the animals underwent nephrectomy for the assessment of the lesions, and then were sacrificed. RESULTS: It was observed that, with the application of RF at the temperatures of 80, 90 and 100 oC, there was a statistically significant difference in the depth (p < 0.001) and width (p < 0.001) of the lesions as between the three temperatures, with a peak in the size of the renal lesions at 90 oC. A statistically significant difference in impedance was observed as between the three temperatures studied (p < 0.001), the most favorable result occurring at 90 oC (least impedance) and similar ones occurring between the temperatures of 80 and 100 oC. The second phase of the study demonstrated that the use of the prostaglandin E1 gave rise to significantly deeper and wider lesions than did the use of adrenaline and also that the tissue resistance was less than with the prostaglandin E1. CONCLUSIONS: It was observed that the temperature of 90oC was more efficient in provoking cell destruction with RF as it produced more extensive lesions both in width and depth than those at the temperatures of 80o and 100 oC (p < 0.001). The impedance was also less at 90 oC (p < 0.001). It was observed that the lesions produced without drugs presented no significant difference with the use of prostaglandin. However, the use of adrenaline provoked smaller lesions (p < 0.001) than did the other two (technical) groups. No viable cells were observed by microscopic analysis within the limits attained by the RF, in either of the experiments

A elevada prevalência da hipertensão arterial sistêmica e as reduzidas taxas de controle tensional obtidas com o tratamento farmacológico despertaram interesse por estratégias alternativas. A denervação simpática renal percutânea surgiu como perspectiva no tratamento de pacientes com hipertensão arterial resistente. As vantagens do cateter irrigado nas ablações cardíacas fomentaram a hipótese de que esse também poderia ser benéfico no contexto da denervação renal. Objetivos: Avaliar a factibilidade e a segurança da denervação simpática renal com cateter irrigado em pacientes com hipertensão arterial resistente. Métodos: O objetivo primário do estudo foi a análise de segurança do procedimento avaliada pela: 1) quantificação de eventos adversos vasculares (em sítio de punção e artéria renal) periprocedimento; 2) Comprometimento da função renal durante o seguimento; 3) ocorrência de estenose/aneurisma da artéria renal, seis meses após a intervenção. Os objetivos secundários foram avaliar: 1) o efeito da denervação renal no comportamento da pressão arterial (aferida em consultório e na MAPA) e no número de anti-hipertensivos, seis meses após a intervenção; 2) o efeito do procedimento na qualidade de vida, aos três meses de seguimento. As variáveis contínuas, ao longo do tempo, foram comparadas utilizando-se os testes t de Student pareado ou Wilcoxon. Para a análise dos dados, utilizaram-se os programas SPSS e STATA11 SE. Valores de p < 0,05 foram considerados estatisticamente significativos. Resultados: Vinte pacientes (idade 50 ± 9,8 anos, 75% mulheres) foram submetidos à denervação renal. As médias das pressões arteriais sistólica e diastólica aferidas no consultório foram de 194,8 ± 36,5mmHg e 112 ± 16,8mmHg, respectivamente. As médias das pressões arteriais sistólica e diastólica aferidas na MAPA foram de 168,4 ± 22,2mmHg e 101,3 ± 19,1mmHg, respectivamente. O número médio de antihipertensivos foi de 7,1 ± 1,5. O procedimento foi realizado sem complicações em 95% dos casos. Em um caso, houve dissecção da artéria renal por trauma mecânico causado pela bainha introdutora. Não foram observadas complicações relacionadas à punção femoral ou elevação dos níveis séricos de creatinina no seguimento. Após seis meses, todos os pacientes foram submetidos à avaliação da integridade vascular. Houve um caso de estenose significativa em artéria renal esquerda, sem repercussão clínica. Ao final de seis meses, observou-se redução de 29,7 ± 33,1mmHg na PAS (p = 0,001) e 14,6 ± 18,9mmHg na PAD (p = 0,003) aferida em consultório, respectivamente. A redução na média da PAS e da PAD, aferida na MAPA, foi de 17,4 ± 33,4mmHg (p = 0,03) e 10,0 ± 21,3mmHg (p = 0,05), respectivamente. Em média, houve redução de 2,6 ± 2,0 anti-hipertensivos (p < 0,01). Antes do procedimento, o valor médio atribuído ao estado de saúde foi de 37,5 ± 22,7 e aumentou para 70,5 ± 20,9 (p = 0,01), três meses após a intervenção. Pacientes que experimentaram redução no número de anti-hipertensivos relataram melhora do estado de saúde. Conclusões: A denervação simpática renal com cateter irrigado é factível e segura. Hipertensos resistentes têm baixos escores do estado de saúde e de qualidade de vida. Os resultados sugerem que esse procedimento reduz os valores pressóricos e melhora a qualidade de vida, na maioria dos pacientes. / The high prevalence of hypertension and reduced blood pressure control obtained with pharmacological treatment aroused interest in alternative therapies. Percutaneous renal sympathetic denervation has emerged as an alternative in the treatment of resistant hypertension. The benefits of irrigated catheter in cardiac ablations fostered the hypothesis that these catheters may also be beneficial for renal denervation. Objectives: To evaluate the feasibility and safety of renal sympathetic enervation for resistant hypertension using an irrigated catheter. Methods: The primary endpoint was the safety of the procedure by means of: 1) periprocedural adverse vascular (puncture site and renal artery) events; 2) changes on renal function during follow-up; 3) evidence of renal artery stenosis/aneurysm at 6 months post-intervention. Secondary objectives were to assess the effects of renal denervation on: 1) blood pressure (difference on office and ABPM between baseline and 6 months of follow-up); 2) number of antihypertensive drugs (difference between baseline and 6 months post-intervention); 3) quality of life (comparison between baseline and 3 months). Continuous variables were compared using the paired Student t test or Wilcoxon test. Data was examined using the SPSS software and STATA11 SE. P values < 0.05 were considered statistically significant. Results: 20 patients (age 50 ± 9.8 years, 75% female) underwent renal denervation. Mean office systolic and diastolic blood pressure was 194.8 ± 36.5mmHg and 112.0 ± 16.8mmHg, respectively. Mean blood pressure on 24 hour ABPM was 168.4 ± 22.2mmHg e 101.3 ± 19.1mmHg, respectively. The mean number of anti-hypertensive drugs was 7.1 ± 1.5; 95% of cases were performed without complications. In one patient, there was a renal artery dissection by mechanical trauma caused by the sheath, resulting in stent implantation. There were no complications related to femoral puncture or elevation of creatinine values during the follow up. All patients were evaluated for vascular integrity at 6months. In one patient, significant left renal artery stenosis was diagnosed. At 6 months, office systolic and diastolic blood pressure reduced 29.7 ± 33.1mmHg (p = 0.001) and 14.6 ± 18.9mmHg (p = 0.003) respectively; Systolic and diastolic blood pressure on ABPM reduced 17.4 ± 33.4mmHg (p = 0.03) and 10.0 ± 21.3mmHg (p = 0.05), respectively. On average, there was a reduction of 2.6 ± 2.0 (p < 0.01) antihypertensive drugs. Before the procedure, the average value attributed to health status was 37.5 ± 22.7 and improved significantly at 3 months (70.5 ± 20.9, p = 0.01). Patients who experienced a reduction in the number of antihypertensive drugs reported improved health status. Conclusions: Renal sympathetic denervation with irrigated catheter is feasible and safe. Hypertensive patients have low quality of life scores. Comparison to post-renal denervation results showed a reduction in blood pressure and better quality of life in most patients.

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.

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

Patients with atrial fibrillation (AF) require modification of ectopic electrical activity to avoid potentially fatal health complications. Catheter ablation therapy is a minimally invasive procedure to create tissue necrosis, called lesion, in areas of abnormal electrical activity. However, significant proportion of patients require repeat treatment from AF recurrences in part by electrical reconnection from incomplete lesions and conduction recovery. Current therapeutic approaches are limited by reliable methods to assess AF structural substrates and validate lesion sufficiency during procedures. In recent years, development of near-infrared optical spectroscopy has provided a non-invasive method to evaluate biological tissue. Near infrared spectroscopy (NIRS) is an optical technique that enables direct characterization of pathological tissue based on the absorption of major chromophores and light scattering. In this thesis, we explore the use of near-infrared optical spectroscopy to identify AF substrates and quantify lesion formation to improve treatment efficacy. First, we developed a near-infrared multispectral imaging system and present a model to assess lesion adequacy by direct visualization of cardiac lesions through an endoscope-integrated probe. Then, a custom single fiber integrated radiofrequency (RF) ablation catheter was fabricated to track irrigated lesion progression real-time on ex vivo swine hearts. A machine learning model was introduced to predict lesion size and transmurality. Additionally, we assess the feasibility of near-infrared spectroscopy by fabricating a NIRS-integrated open-irrigation RF ablation catheter and an algorithm to assess lesion dimensions based on key features derived from NIRS measurements. Using this model, we demonstrate real-time tracking of irrigated lesion delivery in both ex vivo and in vivo swine model. Lastly, we show left atrial endocardial mapping with NIRS-integrated RF mapping catheter to assess AF structural substrates. We present a classification algorithm for important AF structural substrates, such as pulmonary vein sleeve, normal myocardium, ablated tissue, and fibrosis, and a regression model to validate lesion adequacy. A near-infrared spectroscopy-based techniques to localize structural complexities and validate lesion sufficiency at the catheter tip could enhance the understanding of underlying AF substrates and improve treatment efficacy.

Introduction: Overweight and obesity are associated with onset and progression of atrial fibrillation (AF). Catheter ablation is considered a safe and curative therapy in advanced stages of AF.In this retrospective study wewanted toinvestigate the impact of overweight and obesity on AF-recurrence after ablation,in patients with symptomatic AF undergoing successful elective catheter ablation.Methods:The study population included 90 patients with symptomatic AF who received elective catheter ablation at University Hospital Örebro between 2015-2016. Patients were categorized into 3 study groups: Lean (&lt;25.0 kg/m2), Overweight (25.0-29.9 kg/m2) and Obese (≥30 kg/m2). Recurrence was defined as clinical symptoms and electrocardiogram (ECG)recording consistent with AF within 3 -12 months after ablation.Fisher’s exact test was used to compare AF-recurrence between BMI groups. Results:Out of 90 patients included, 3 were excluded due to missing data. BMI-categories consisted of 17 (19.6%) lean, 47 (54.0%) overweight and 23 (26,4%) obesepatients. Recurrence rates in the different groups were 5.9% in the lean group, 29.8%in the overweight group and 17.4% in the obese group.Compared to lean patients, AF-recurrence was statistically significantly higher in the overweight population (p=0.04), but not in the obese population (p=0.3). BMI was not an independent predictor of AF-recurrence after ablation in the univariate (p=0.52) and multivariate logistic regression analysis (p=0.18).Conclusion:Compared to lean patients,recurrence of AF after catheter ablation was statistically significantly higher in overweight patients, but not in obese patients. BMI seemed not to be an independent predictor of AF-recurrence.

O objetivo deste estudo foi avaliar retrospectivamente, em longo-prazo, os preditores de recorrência de fibrilação atrial paroxística (FA) em 139 pacientes submetidos à ablação por radiofreqüência, através das técnicas ostial ou extraostial de abordagem do átrio esquerdo, associadas ou não à ablação do istmo cavo-tricuspídeo (ICT). Variáveis pré, intra e pós-ablação foram avaliadas por análise uni e multivariada, para determinar os preditores de recorrência da FA após um procedimento. Observou-se que maior tempo de história de FA, uso de mais antiarrítmicos e recorrência de FA dentro de 60 dias pós-procedimento, aumentaram o risco de recorrência de FA a longo-prazo. Por outro lado, a associação de flutter atrial e a ablação concomitante do ICT, reduziram o risco de recorrência ao final de 33 ±12 meses. / The objective of this study was to evaluate in retrospect, in long-term, the predictors of late recurrence of atrial fibrillation (AF) in 139 patients submitted to the ablation by radiofrequency, through the techniques ostial or extra-ostial of approach of the atrium left, associated or not to the ablation of the cavotricuspid isthmus(ICT). Variables pre, intra and post-ablation were appraised for analysis uni and multivariated, to determine the predictors of recurrence of AF after one procedure. It was observed that larger time of history of AF, use of more drugs and recurrence of AF within 60 days after procedure; they increased the risk of recurrence of AF in long-term. On the other hand, the association of atrial flutter and the concomitant ablation of ICT, they reduced the recurrence risk at the end of 33 ±12 months.