Elucidating the Complex Oxidation Behavior of Aqueous H3PO3 on Pt Electrodes via In Situ Tender X-ray Absorption Near-Edge Structure Spectroscopy at the P K-Edge.

In situ tender X-ray absorption near-edge structure (XANES) spectroscopy at the P K-edge was utilized to investigate the oxidation mechanism of aqueous H3PO3 on Pt electrodes under various conditions relevant to high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) applications. XANES and electrochemical analysis were conducted under different tender X-ray irradiation doses, revealing that intense radiation induces the oxidation of aqueous H3PO3 via H2O yielding H3PO4 and H2. A broadly applicable experimental procedure was successfully developed to suppress these undesirable radiation-induced effects, enabling a more accurate determination of the aqueous H3PO3 oxidation mechanism. In situ XANES studies of aqueous 5 mol dm-3 H3PO3 on electrodes with varying Pt availability and surface roughness reveal that Pt catalyzes the oxidation of aqueous H3PO3 to H3PO4. This oxidation is enhanced upon applying a positive potential to the Pt electrode or raising the electrolyte temperature, the latter being corroborated by complementary ion-exchange chromatography measurements. Notably, all of these oxidation processes involve reactions with H2O, as further supported by XANES measurements of aqueous H3PO3 of different concentrations, showing a more pronounced oxidation in electrolytes with a higher H2O content. The significant role of water in the oxidation of H3PO3 to H3PO4 supports the reaction mechanisms proposed for various chemical processes observed in this work and provides valuable insights into potential strategies to mitigate Pt catalyst poisoning by H3PO3 during HT-PEMFC operation.

Oxidation of Aqueous Phosphorous Acid Electrolyte in Contact with Pt Studied by X-ray Photoemission Spectroscopy.

The oxidation of the aqueous H3PO3 in contact with Pt was investigated for a fundamental understanding of the Pt/aqueous H3PO3 interaction with the goal of providing a comprehensive basis for the further optimization of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Ion-exchange chromatography (IEC) experiments suggested that in ambient conditions, Pt catalyzes H3PO3 oxidation to H3PO4 with H2O. X-ray photoelectron spectroscopy (XPS) on different substrates, including Au and Pt, previously treated in H3PO3 solutions was conducted to determine the catalytic abilities of selected metals toward H3PO3 oxidation. In situ ambient pressure hard X-ray photoelectron spectroscopy (AP-HAXPES) combined with the "dip-and-pull" method was performed to investigate the state of H3PO3 at the Pt|H3PO3 interface and in the bulk solution. It was shown that whereas H3PO3 remains stable in the bulk solution, the catalyzed oxidation of H3PO3 by H2O to H3PO4 accompanied by H2 generation occurs in contact with the Pt surface. This catalytic process likely involves H3PO3 adsorption at the Pt surface in a highly reactive pyramidal tautomeric configuration.

[CRCP units: a strategy to assess health risks in children in contaminated communitiesUnidades RISC: uma estratégia para avaliar os riscos de saúde na população infantil de comunidades contaminadas]. / Unidades RISC: una estrategia para evaluar riesgos de salud en la población infantil de comunidades contaminadas.

Humanitarian crises can occur in places affected by chemical, physical, biological, and social threats, especially when these threats interact with each other and cause a syndemic. In order to avoid crises in these places, it is necessary to introduce mitigation measures that we have framed as "humanitarian scenarios". Due to their nature, implementation of these interventions requires the creation of multidisciplinary operational groups with a work strategy that integrates them into the affected community. In the case of the child population, the operational group was called the 'childhood risks in contaminated places' (CRCP) unit; contaminated places meaning localities impacted by chemical, physical, or biological threats. The strategy has six phases: (i) planning the survey and site visit; (ii) community involvement in identifying threats, vulnerabilities, and routes of exposure (the path of pollutants from their source to the receiving population), and in preparing joint work for the subsequent phases; iii) prioritization of risks identified through environmental monitoring and use of biomarkers of exposure and effects; iv) risk prevention through the creation of various 'capacities and alternatives for the prevention of syndemic threats'; (v) advocacy to implement these capacities and alternatives through risk communication and local training; and (vi) protection through measures that include telehealth, social progress, and innovation to improve health coverage. The strategy has been implemented in different contexts, and in some of them it has been enriched by analysis of respect for human rights.

Crises humanitárias podem ocorrer em locais afetados por ameaças químicas, físicas, biológicas e sociais, principalmente quando essas ameaças interagem entre si e causam uma sindemia. Para evitar as crises, é necessário introduzir nesses locais medidas de mitigação que enquadramos no termo "cenários humanitários". Por sua natureza, a implementação de tais ações de intervenção exige a formação de grupos operacionais multidisciplinares e de uma estratégia de trabalho que permita integrá-los à comunidade afetada. No caso da população infantil, o grupo operacional recebeu o nome de Unidade de Riscos Infantis em Áreas Contaminadas (na sigla em espanhol, RISC), ou seja, em locais impactados por ameaças químicas, físicas ou biológicas. A estratégia consiste nas seis fases a seguir: i) planejamento para o estudo e visita ao local; ii) participação da comunidade para identificar ameaças, vulnerabilidades e rotas de exposição (caminho que os contaminantes devem seguir desde a sua fonte até a população receptora), bem como para o trabalho conjunto nas fases seguintes; iii) priorização dos riscos identificados por meio do monitoramento ambiental e uso de biomarcadores de exposição e efeitos; iv) prevenção de riscos por meio da criação de diversas capacidades e alternativas para a prevenção diante de ameaças sindêmicas (CAPAS); v) promoção da implantação das CAPAS por meio da comunicação de riscos e capacitação local; e vi) proteção com medidas que incluem propostas de telessaúde, progresso social e inovação para melhorar a cobertura de saúde. A estratégia foi aplicada em diferentes contextos, em alguns dos quais foi enriquecida com uma análise do respeito pelos direitos humanos.

Unidades RISC: una estrategia para evaluar riesgos de salud en la población infantil de comunidades contaminadas

[RESUMEN]. Las crisis humanitarias pueden presentarse en sitios afectados por amenazas químicas, físicas, biológicas y sociales, sobre todo cuando estas amenazas interaccionan entre sí y causan una sindemia. A fin de evitar las crisis, en estos sitios se hace necesario introducir medidas de mitigación que hemos enmarcado bajo el término de “escenarios humanitarios”. Debido a su naturaleza, la implementación de dichas acciones de intervención requiere de la conformación de grupos operativos multidisciplinarios y de una estrategia de trabajo que permita integrarlos con la comunidad afectada. En el caso de la población infantil, el grupo ope- rativo recibió el nombre de unidad de riesgos infantiles en sitios contaminados (RISC), es decir, en localidades impactadas por amenazas químicas, físicas o biológicas. La estrategia consta de las siguientes seis fases: i) planificación para el estudio y la visita al sitio; ii) participación de la comunidad para identificar amena- zas, vulnerabilidades y rutas de exposición (el camino que deben seguir los contaminantes desde su fuente hasta la población receptora), así como para el trabajo conjunto en las siguientes fases; iii) priorización de riesgos identificados mediante el monitoreo ambiental y uso de biomarcadores de exposición y efectos; iv) prevención de riesgos a través de la creación de diversas capacidades y alternativas para la prevención ante amenazas sindémicas (CAPAS); v) promoción para implementar las CAPAS mediante la comunicación de riesgos y la capacitación local; y vi) protección con medidas que incluyen propuestas de telesalud, progreso social e innovación para mejorar la cobertura sanitaria. La estrategia ha sido aplicada en diferentes contextos, en algunos de los cuales, ha sido enriquecida con el análisis del respeto de los derechos humanos.

[ABSTRACT]. Humanitarian crises can occur in places affected by chemical, physical, biological, and social threats, espe- cially when these threats interact with each other and cause a syndemic. In order to avoid crises in these places, it is necessary to introduce mitigation measures that we have framed as "humanitarian scenarios". Due to their nature, implementation of these interventions requires the creation of multidisciplinary operational groups with a work strategy that integrates them into the affected community. In the case of the child popula- tion, the operational group was called the ‘childhood risks in contaminated places’ (CRCP) unit; contaminated places meaning localities impacted by chemical, physical, or biological threats. The strategy has six phases: (i) planning the survey and site visit; (ii) community involvement in identifying threats, vulnerabilities, and routes of exposure (the path of pollutants from their source to the receiving population), and in preparing joint work for the subsequent phases; iii) prioritization of risks identified through environmental monitoring and use of bio- markers of exposure and effects; iv) risk prevention through the creation of various ‘capacities and alternatives for the prevention of syndemic threats’; (v) advocacy to implement these capacities and alternatives through risk communication and local training; and (vi) protection through measures that include telehealth, social pro- gress, and innovation to improve health coverage. The strategy has been implemented in different contexts, and in some of them it has been enriched by analysis of respect for human rights.

[RESUMO]. Crises humanitárias podem ocorrer em locais afetados por ameaças químicas, físicas, biológicas e sociais, principalmente quando essas ameaças interagem entre si e causam uma sindemia. Para evitar as crises, é necessário introduzir nesses locais medidas de mitigação que enquadramos no termo “cenários huma- nitários”. Por sua natureza, a implementação de tais ações de intervenção exige a formação de grupos operacionais multidisciplinares e de uma estratégia de trabalho que permita integrá-los à comunidade afe- tada. No caso da população infantil, o grupo operacional recebeu o nome de Unidade de Riscos Infantis em Áreas Contaminadas (na sigla em espanhol, RISC), ou seja, em locais impactados por ameaças químicas, físicas ou biológicas. A estratégia consiste nas seis fases a seguir: i) planejamento para o estudo e visita ao local; ii) participação da comunidade para identificar ameaças, vulnerabilidades e rotas de exposição (caminho que os contaminantes devem seguir desde a sua fonte até a população receptora), bem como para o trabalho conjunto nas fases seguintes; iii) priorização dos riscos identificados por meio do monitoramento ambiental e uso de biomarcadores de exposição e efeitos; iv) prevenção de riscos por meio da criação de diversas capacidades e alternativas para a prevenção diante de ameaças sindêmicas (CAPAS); v) promoção da implantação das CAPAS por meio da comunicação de riscos e capacitação local; e vi) proteção com medi- das que incluem propostas de telessaúde, progresso social e inovação para melhorar a cobertura de saúde. A estratégia foi aplicada em diferentes contextos, em alguns dos quais foi enriquecida com uma análise do respeito pelos direitos humanos.

Unidades RISC: una estrategia para evaluar riesgos de salud en la población infantil de comunidades contaminadas / CRCP units: a strategy to assess health risks in children in contaminated communities / Unidades RISC: uma estratégia para avaliar os riscos de saúde na população infantil de comunidades contaminadas

RESUMEN Las crisis humanitarias pueden presentarse en sitios afectados por amenazas químicas, físicas, biológicas y sociales, sobre todo cuando estas amenazas interaccionan entre sí y causan una sindemia. A fin de evitar las crisis, en estos sitios se hace necesario introducir medidas de mitigación que hemos enmarcado bajo el término de "escenarios humanitarios". Debido a su naturaleza, la implementación de dichas acciones de intervención requiere de la conformación de grupos operativos multidisciplinarios y de una estrategia de trabajo que permita integrarlos con la comunidad afectada. En el caso de la población infantil, el grupo operativo recibió el nombre de unidad de riesgos infantiles en sitios contaminados (RISC), es decir, en localidades impactadas por amenazas químicas, físicas o biológicas. La estrategia consta de las siguientes seis fases: i) planificación para el estudio y la visita al sitio; ii) participación de la comunidad para identificar amenazas, vulnerabilidades y rutas de exposición (el camino que deben seguir los contaminantes desde su fuente hasta la población receptora), así como para el trabajo conjunto en las siguientes fases; iii) priorización de riesgos identificados mediante el monitoreo ambiental y uso de biomarcadores de exposición y efectos; iv) prevención de riesgos a través de la creación de diversas capacidades y alternativas para la prevención ante amenazas sindémicas (CAPAS); v) promoción para implementar las CAPAS mediante la comunicación de riesgos y la capacitación local; y vi) protección con medidas que incluyen propuestas de telesalud, progreso social e innovación para mejorar la cobertura sanitaria. La estrategia ha sido aplicada en diferentes contextos, en algunos de los cuales, ha sido enriquecida con el análisis del respeto de los derechos humanos.

ABSTRACT Humanitarian crises can occur in places affected by chemical, physical, biological, and social threats, especially when these threats interact with each other and cause a syndemic. In order to avoid crises in these places, it is necessary to introduce mitigation measures that we have framed as "humanitarian scenarios". Due to their nature, implementation of these interventions requires the creation of multidisciplinary operational groups with a work strategy that integrates them into the affected community. In the case of the child population, the operational group was called the 'childhood risks in contaminated places' (CRCP) unit; contaminated places meaning localities impacted by chemical, physical, or biological threats. The strategy has six phases: (i) planning the survey and site visit; (ii) community involvement in identifying threats, vulnerabilities, and routes of exposure (the path of pollutants from their source to the receiving population), and in preparing joint work for the subsequent phases; iii) prioritization of risks identified through environmental monitoring and use of biomarkers of exposure and effects; iv) risk prevention through the creation of various 'capacities and alternatives for the prevention of syndemic threats'; (v) advocacy to implement these capacities and alternatives through risk communication and local training; and (vi) protection through measures that include telehealth, social progress, and innovation to improve health coverage. The strategy has been implemented in different contexts, and in some of them it has been enriched by analysis of respect for human rights.

RESUMO Crises humanitárias podem ocorrer em locais afetados por ameaças químicas, físicas, biológicas e sociais, principalmente quando essas ameaças interagem entre si e causam uma sindemia. Para evitar as crises, é necessário introduzir nesses locais medidas de mitigação que enquadramos no termo "cenários humanitários". Por sua natureza, a implementação de tais ações de intervenção exige a formação de grupos operacionais multidisciplinares e de uma estratégia de trabalho que permita integrá-los à comunidade afetada. No caso da população infantil, o grupo operacional recebeu o nome de Unidade de Riscos Infantis em Áreas Contaminadas (na sigla em espanhol, RISC), ou seja, em locais impactados por ameaças químicas, físicas ou biológicas. A estratégia consiste nas seis fases a seguir: i) planejamento para o estudo e visita ao local; ii) participação da comunidade para identificar ameaças, vulnerabilidades e rotas de exposição (caminho que os contaminantes devem seguir desde a sua fonte até a população receptora), bem como para o trabalho conjunto nas fases seguintes; iii) priorização dos riscos identificados por meio do monitoramento ambiental e uso de biomarcadores de exposição e efeitos; iv) prevenção de riscos por meio da criação de diversas capacidades e alternativas para a prevenção diante de ameaças sindêmicas (CAPAS); v) promoção da implantação das CAPAS por meio da comunicação de riscos e capacitação local; e vi) proteção com medidas que incluem propostas de telessaúde, progresso social e inovação para melhorar a cobertura de saúde. A estratégia foi aplicada em diferentes contextos, em alguns dos quais foi enriquecida com uma análise do respeito pelos direitos humanos.

Taquicardia tipo torcida de puntas secundaria a prolongación del intervalo QT por uso de Amitriptilina a propósito de un caso / Torsades de pointes due to prologed QT interval by amitriptilin use

El intervalo QT representa la actividad eléctrica ventricular, tanto la despolarización como la repolarización. Definimos como intervalo QT prolongado a una medida del QT corregido > 450 ms en varones y > 470 ms en mujeres. Se diferencian 2 grandes grupos dentro del síndrome del QT prolongado: el congénito, asociado con mutaciones en determinados genes, y la variante adquirida. El síndrome de QT prolongado es un conjunto de entidades infrecuentes que se manifiestan en el ECG por la prolongación del intervalo QT y la predisposición a la taquicardia ventricular polimórfica. Una de las principales etiologías del síndrome de QT congénito adquirido es el uso de fármacos prolongadores del intervalo QT. En la actualidad la lista de fármacos que pueden prolongarlo a dosis terapéuticas es amplia y está en continuo crecimiento. La prolongación del intervalo QT puede predisponer a la aparición de taquicardia ventricular polimórfica grave denominada torcida de puntas (TdP), cuya aparición no es muy frecuente, pero es causa de muerte súbita. En el presente reporte presentamos un caso de desarrollo de torcida de puntas debido a uso de amitriptilina

Dual Oxygen Defects in Layered La1.2Sr0.8-xBaxInO4+δ (x = 0.2, 0.3) Oxide-Ion Conductors: A Neutron Diffraction Study.

The title compounds exhibit a K2NiF4-type layered perovskite structure; they are based on the La1.2Sr0.8InO4+δ oxide, which was found to exhibit excellent features as fast oxide-ion conductor via an interstitial oxygen mechanism. These new Ba-containing materials were designed to present a more open framework to enhance oxygen conduction. The citrate-nitrate soft-chemistry technique was used to synthesize such structural perovskite-type materials, followed by annealing in air at moderate temperatures (1150 °C). The subtleties of their crystal structures were investigated from neutron powder diffraction (NPD) data. They crystallize in the orthorhombic Pbca space group. Interstitial O3 oxygen atoms were identified by difference Fourier maps in the NaCl layer of the K2NiF4 structure. At variance with the parent compound, conspicuous oxygen vacancies were found at the O2-type oxygen atoms for x = 0.2, corresponding to the axial positions of the InO6 octahedra. The short O2-O3 distances and the absence of steric impediments suggest a dual oxygen-interstitial mechanism for oxide-ion conduction in these materials. Conductivity measurements show that the activation energy values are comparable to those typical of ionic conductors working by simple vacancy mechanisms (~1 eV). The increment of the total conductivity for x = 0.2 can be due to the mixed mechanism driving both oxygen vacancies and interstitials, which is original for these potential electrolytes for solid-oxide fuel cells.

The "CHILD" framework for the study of artisanal mercury mining communities.

In this paper, our group reports the use of a new framework in sites contaminated with mercury. This is significant because under the Minamata Convention on Mercury each Party shall endeavor to develop appropriate strategies for identifying and assessing sites contaminated by mercury or mercury compounds. This new approach, the "CHILD" framework has five steps: i) Community-based risk characterization; ii) Habilitation; iii) Intervention; iv) Laws and Regulation; and v) Development. We are using this framework in three mercury artisanal mining sites, and preliminary results are depicted in this report.

Electrochemical adsorption of OH on Pt(111) in alkaline solutions: combining DFT and molecular dynamics.

The adsorption of OH on Pt(111) in alkaline solution has been investigated by a method that combines density functional theory, molecular dynamics, and quantum statistical mechanics. In particular, we have calculated the free energy surface for the reaction. A physisorbed hydroxide ion in a metastable state and a stable adsorbed uncharged OH group are observed. The energy of activation at equilibrium is comparatively low, so that the reaction is fast.

Permanent pacing in patients with Chagas' disease.

BACKGROUND: Chagas' disease is an endemic disease in most Latin American countries. The cardiomyopathy associated with this condition often requires permanent pacing due to bradycardia. The aim of this study was to compare the indications for pacemaker implantation, intraoperative measurements, and long-term follow-up of patients with Chagas' cardiomyopathy (ChCM) and ischemic cardiomyopathy (ICM) referred for pacemaker implantation. METHODS: Retrospective study including consecutive patients with ChCM (Group 1) and ICM (Group 2), who underwent pacemaker implantation in a single center. RESULTS: We analyzed 360 patients. Patients in Group 1 were younger (66.29 ± 7.01 vs 75.3 ± 7.11 years; P = 0.0001) and more often male (72% vs 60%; P = 0.05). Sinus node dysfunction (SND) was more prevalent in Group 1 (70% vs 52%; P = 0.03). Atrioventricular block was less prevalent in Group 1 (30% vs 48%; P = 0.04). No significant differences were found with respect to left ventricular ejection fraction (54.2 ± 9.1 vs 53.4 ± 8.2%; P = NS) and baseline QRS duration (119 ± 34 vs 108 ± 29 ms; P = NS). Right bundle branch block was more frequent in Group 1 (44% vs 12%; P = 0.0001), and left bundle branch block in Group 2 (6% vs 22%; P = 0.0001). Implantation time was longer in Group 1 (39 ± 19 vs 29 ± 13 minutes; P = 0.001) and was with higher atrial and ventricular pacing thresholds (1.4 ± 0.8 vs 1.0 ± 0.5 V; P = 0.001 and 1.2 ± 0.8 vs 0.6 ± 0.8 V; P = 0.001, respectively). During a follow-up of 42.8 ± 13.6 months, Group 1 had a higher incidence of new atrial fibrillation (34% vs 25.5%; P = 0.001), and there was a nonsignificant trend toward more displacements of the ventricular lead (6% vs 3.5%; P = 0.3). There were no deaths during the follow-up. CONCLUSIONS: ChCM patients receiving pacemakers are younger and more frequently have SND compared to those with ICM. Pacemaker implant is longer in patients with ChCM disease and is with higher pacing thresholds. The incidence of new atrial fibrillation during the follow-up is significantly higher in patients with ChCM.

Bidirectional ventricular tachycardia: a hallmark of catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia is a familial cardiac arrhythmia that is related to RYR2 or CASQ2 gene mutation. It occurs in patients with structurally normal heart and causes exercise-emotion triggered syncope and sudden cardiac death. We present a 13 year-old girl with recurrent episodes of exercise-related syncope and prior history of sudden death in a first degree relative.

Resultados del uso de marcapasos definitivo en pacientes con cardiopatía chagásica y con enfermedad coronaria / Results of the use of definitive pacemakers in patients with chagasic cardiomyopathy and in patients with coronary artery disease

En la mayoría de los países de Latinoamérica, la enfermedad de Chagas es endémica y la miocardiopatía isquémica es la primera causa de afección cardíaca. Ambas entidades conviven generando un modelo biológico y epidemiológico único, y al ser enfermedades de evolución crónica, por diversos motivos pueden requerir el implante de un marcapasos definitivo. El objetivo del presente trabajo fue comparar los motivos de implante, detalles técnicos y evolución de pacientes referidos para tratamiento con marcapasos definitivo y portadores de miocardiopatía chagásica o miocardiopatía isquémica.

Resultados del uso de marcapasos definitivo en pacientes con cardiopatía chagásica y con enfermedad coronaria / Results of the use of definitive pacemakers in patients with chagasic cardiomyopathy and in patients with coronary artery disease

En la mayoría de los países de Latinoamérica, la enfermedad de Chagas es endémica y la miocardiopatía isquémica es la primera causa de afección cardíaca. Ambas entidades conviven generando un modelo biológico y epidemiológico único, y al ser enfermedades de evolución crónica, por diversos motivos pueden requerir el implante de un marcapasos definitivo. El objetivo del presente trabajo fue comparar los motivos de implante, detalles técnicos y evolución de pacientes referidos para tratamiento con marcapasos definitivo y portadores de miocardiopatía chagásica o miocardiopatía isquémica. (AU)

Ventricular flutter triggered by fever in a patient with Brugada syndrome.

Brugada syndrome is a clinical-electrocardiographic entity predisposing to malignant ventricular arrhythmias. The typical arrhythmia is polymorphic ventricular tachycardia, which can potentially degenerate to ventricular fibrillation. Monomorphic ventricular tachycardia is uncommon. Our group is reporting the case of a 39-year-old man with known Brugada syndrome who developed ventricular flutter while febrile. Fever has previously been shown to unmask Brugada changes and to induce ventricular arrhythmias. The appearance of monomorphic ventricular tachycardia potentially attributable to sodium-channel dysfunction further confounds the mechanism of arrhythmogenesis in Brugada syndrome. This curious occurrence further underlines the likely complex nature of arrhythmogenesis in Brugada syndrome.

Surface fragmented QRS in a patient with hypertrophic cardiomyopathy and malignant arrhythmias: Is there an association?

An 18- year old woman with hypertrophic cardiomyopathy, aborted sudden cardiac death and implanted with an implantable cardioverter defibrillator (ICD), developed progressive fragmentation of her surface 12-lead electrocardiogram (ECG). During the follow-up, she presented with multiple appropriate ICD discharges. Here, we discuss the possible association between surface fragmented ECG and the risk of ventricular arrhythmias in patients with hypertrophic cardiomyopathy.

Long-term results of slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia: simple approach.

AIMS: The aim of this study was to report the short- and long-term results of slow pathway radiofrequency (RF) ablation in patients with atrioventricular (AV) nodal reentrant tachycardia (AVNRT) using a simplified approach (2 catheters and short applications of RF). MATERIALS AND METHODS: This was a retrospective study that included consecutive patients with AVNRT. We used an anatomical approach with only 2 catheters. Decremental AV nodal conduction and atrial-His conduction interval jump were measured. To detect the onset of the QRS, we used surface lead II. During the stimulation protocol, we performed S2-QRS and S3-QRS measurements. An increase in the S3-QRS3 interval of 50 milliseconds or greater in response to a decrease in the S2-QRS2 coupling interval of 10 milliseconds was defined as a discontinuous AV nodal function curve and taken as evidence of dual antegrade AV pathways. Atrioventricular nodal reentrant tachycardia was demonstrated by the presence of dual AV nodal physiology, atrial echoes, and tachycardia induction with a 1:1 AV relationship and a VA interval of less than 70 milliseconds. Short RF applications (10-15 seconds) were delivered at an intermediate point between the posteroseptal and medioseptal regions of the Koch triangle. The applications were considered effective when junctional rhythm appeared. The end point was the demonstration of slow pathway modification without AVNRT induction. RESULTS: Three hundred forty-four patients (age, 49.22 ± 17.47 years; 254 were female) were included. Discontinuous AV nodal function curves were found in 271 patients (78.77%), and short-term success was achieved in all patients. The anterograde jump in AV nodal conduction was abolished after RF in 222 patients (81.91%), and discontinuous AV nodal conduction and single AV nodal echo beats persisted in 49 cases (18%). The mean number of RF application was 7.79 ± 2.23, the mean number of effective applications was 4.63 ± 0.62, and the mean RF application time was 54.92 ± 8.03 seconds. The total procedure and fluoroscopy time was 29.45 ± 9.6 and 10.87 ± 2.36 minutes, respectively. After the procedure, all patients were followed up for a mean of 46.44 ± 18.89 months, and 7 patients (2%) presented AVNRT recurrences. Complications were observed in 4 patients (1.16%); no permanent AV block was observed. CONCLUSION: In this study, slow pathway RF ablation using a simplified approach technique is an effective and safe approach for the treatment of AVNRT.

Radiofrequency ablation of a left accessory pathway unmasks classic Chagas' disease ECG pattern.

In patients with chronic Chagas' cardiomyopathy, there are forms of the disease that affect the electrical conduction system almost exclusively. The most common disorders include right bundle branch block alone or in association with left anterior fascicular block. We present an unusual case of a patient with Chagas' cardiomyopathy in association with a preexcitation syndrome.

[Is the head-up tilt-test necessary in patients whit clinical diagnosis of vasovagal syncope? Results using a non-sensitized protocol]. / ¿Es necesaria la prueba de inclinación en pacientes con diagnóstico clínico de síncope vasovagal? Resultados utilizando un protocolo no sensibilizado.

INTRODUCTION: Tilt table testing is a simple, non-invasive, low risk test. A not sensitized protocol has been presented in order to shorten the duration of the test. OBJECTIVE: To determine the usefulness of a not sensitized tilt table testing and to compare the results with the pre-test probability, given by the Calgary's score. METHODS: We included patients≥15 years-old with syncope or presyncope with high probability pretest for a vasovagal origin, using the Calgary' score. RESULTS: Seventy patients were analyzed; age 39±20 years old, 66% female. More than 94% of the patients presented a score≥-1, but only 30% of the tilt tests were positive. A score≥-2 was not associated with the result of tilt test. Most of the patients presented a score of 1 (52) and 2 (11), resulting in positive tilt test 32% y 9%, respectively. Among patients with low pre-test probability there was a greater number of negative results (100% with a score of -2 and 50% with score of -5). CONCLUSIONS: This study showed that in patients with vasovagal syncope suggested by clinical assessment, a not sensitized tilt test did not provide additional information, with a significant number of false negatives.

¿Es necesaria la prueba de inclinación en pacientes con diagnóstico clínico de síncope vasovagal?: Resultados utilizando un protocolo no sensibilizado / Is the head-up tilt-test necessary in patients whit clinical diagnosis of vasovagal syncope?: Results using a non-sensitized protocol

Introducción:La prueba de inclinación es un estudio no invasivo, sencillo y de bajo riesgo, donde la utilización de protocolos no sensibilizados sirven para acortar los tiempos de la prueba. Objetivo:Determinar en pacientes con síncope la utilidad de la prueba de inclinación no sensibilizada con fármacos y comparar los resultados con la probabilidad clínica pre-test. Métodos:Se incluyeron pacientes >15 años de edad, con síncope o presíncope, con clínica sugestiva de origen vasovagal, utilizando la escala de Calgary. Resultados:Se analizaron 70 pacientes; edad: 39 ± 20 años, 66% mujeres. De los pacientes, 94% presentó una puntuación >-1, pero sólo 30% de las pruebas fueron positivas. Una puntuación >-2 no se asoció con el resultado de la prueba. La mayoría de los pacientes presentaron una puntuación de 1 (52) y 2 (11), resultando en una prueba positiva en 32% y 9%, respectivamente. En pacientes con probabilidad pre-test baja, hubo mayor número de pruebas negativas (100% con una puntuación de -2 y 50% con puntuación de -5). Conclusiones:El estudio mostró que en pacientes con síncope vasovagal, sugerido por la evaluación clínica, la prueba de inclinación no sensibilizada no proporcionó información adicional, con un número significativo de falsos negativos.

Introduction:Tilt table testing is a simple, non-invasive, low risk test. A not sensitized protocol has been presented in order to shorten the duration of the test. Objective:To determine the usefulness of a not sensitized tilt table testing and to compare the results with the pre-test probability, given by the Calgary's score. Methods:We included patients >15 years-old with syncope or presyncope with high probability pretest for a vasovagal origin, using the Calgary' score. Results:Seventy patients were analyzed; age 39 ± 20 years old, 66% female. More than 94% of the patients presented a score >-1, but only 30% of the tilt tests were positive. A score >-2 was not associated with the result of tilt test. Most of the patients presented a score of 1 (52) and 2 (11), resulting in positive tilt test 32% y 9%, respectively. Among patients with low pre-test probability there was a greater number of negative results (100% with a score of -2 and 50% with score of -5). Conclusions: This study showed that in patients with vasovagal syncope suggested by clinical assessment, a not sensitized tilt test did not provide additional information, with a significant number of false negatives.