Development and Long-Term Follow-Up of an Experimental Model of Myocardial Infarction in Rabbits.

A chronic model of acute myocardial infarction was developed to study the mechanisms involved in adverse postinfarction ventricular remodeling. In an acute myocardial infarction (AMI), the left circumflex coronary artery of New Zealand White rabbits (n = 9) was occluded by ligature for 1 h, followed by reperfusion. A specific care protocol was applied before, during, and after the intervention, and the results were compared with those of a sham operated group (n = 7). After 5 weeks, programmed stimulation and high-resolution mapping were performed on isolated and perfused hearts using the Langendorff technique. The infarct size determined by 2,3,5-triphenyltetrazolium chloride inside of the area at risk (thioflavin-S) was then determined. The area at risk was similar in both groups (54.33% (experimental infarct group) vs. 58.59% (sham group), ns). The infarct size was 73.16% as a percentage of the risk area. The experimental infarct group had a higher inducibility of ventricular arrhythmias (100% vs. 43% in the sham group, p = 0.009). A reproducible chronic experimental model of myocardial infarction is presented in which the extent and characteristics of the lesions enable the study of the vulnerability to develop ventricular arrhythmias because of the remodeling process that occurs during cardiac tissue repair.

Effect of chronic exercise on myocardial electrophysiological heterogeneity and stability. Role of intrinsic cholinergic neurons: A study in the isolated rabbit heart.

A study has been made of the effect of chronic exercise on myocardial electrophysiological heterogeneity and stability, as well as of the role of cholinergic neurons in these changes. Determinations in hearts from untrained and trained rabbits on a treadmill were performed. The hearts were isolated and perfused. A pacing electrode and a recording multielectrode were located in the left ventricle. The parameters determined during induced VF, before and after atropine (1µM), were: fibrillatory cycle length (VV), ventricular functional refractory period (FRPVF), normalized energy (NE) of the fibrillatory signal and its coefficient of variation (CV), and electrical ventricular activation complexity, as an approach to myocardial heterogeneity and stability. The VV interval was longer in the trained group than in the control group both prior to atropine (78±10 vs. 68±10 ms) and after atropine (76±8 vs. 67±10 ms). Likewise, FRPVF was longer in the trained group than in the control group both prior to and after atropine (53±8 vs. 42±7 ms and 50±6 vs. 40±6 ms, respectively), and atropine did not modify FRPVF. The CV of FRPVF was lower in the trained group than in the control group prior to atropine (12.5±1.5% vs. 15.1±3.8%) and, decreased after atropine (15.1±3.8% vs. 12.2±2.4%) in the control group. The trained group showed higher NE values before (0.40±0.04 vs. 0.36±0.05) and after atropine (0.37±0.04 vs. 0.34±0.06; p = 0.08). Training decreased the CV of NE both before (23.3±2% vs. 25.2±4%; p = 0.08) and after parasympathetic blockade (22.6±1% vs. 26.1±5%). Cholinergic blockade did not modify these parameters within the control and trained groups. Activation complexity was lower in the trained than in the control animals before atropine (34±8 vs. 41±5), and increased after atropine in the control group (41±5 vs. 48±9, respectively). Thus, training decreases the intrinsic heterogeneity of the myocardium, increases electrophysiological stability, and prevents some modifications due to muscarinic block.

Effects of the Inhibition of Late Sodium Current by GS967 on Stretch-Induced Changes in Cardiac Electrophysiology.

PURPOSE: Mechanical stretch increases sodium and calcium entry into myocytes and activates the late sodium current. GS967, a triazolopyridine derivative, is a sodium channel blocker with preferential effects on the late sodium current. The present study evaluates whether GS967 inhibits or modulates the arrhythmogenic electrophysiological effects of myocardial stretch. METHODS: Atrial and ventricular refractoriness and ventricular fibrillation modifications induced by acute stretch were studied in Langendorff-perfused rabbit hearts (n = 28) using epicardial multiple electrodes and high-resolution mapping techniques under control conditions and during the perfusion of GS967 at different concentrations (0.03, 0.1, and 0.3 µM). RESULTS: On comparing ventricular refractoriness, conduction velocity and wavelength obtained before stretch had no significant changes under each GS967 concentration while atrial refractoriness increased under GS967 0.3 µM. Under GS967, the stretch-induced changes were attenuated, and no significant differences were observed between before and during stretch. GS967 0.3 µM diminished the normal stretch-induced changes resulting in longer (less shortened) atrial refractoriness (138 ± 26 ms vs 95 ± 9 ms; p < 0.01), ventricular refractoriness (155 ± 18 ms vs 124 ± 16 ms; p < 0.01) and increments in spectral concentration (23 ± 5% vs 17 ± 2%; p < 0.01), the fifth percentile of ventricular activation intervals (46 ± 8 ms vs 31 ± 3 ms; p < 0.05), and wavelength of ventricular fibrillation (2.5 ±0.5 cm vs 1.7 ± 0.3 cm; p < 0.05) during stretch. The stretch-induced increments in dominant frequency during ventricular fibrillation (control = 38%, 0.03 µM = 33%, 0.1 µM = 33%, 0.3 µM = 14%; p < 0.01) and the stretch-induced increments in arrhythmia complexity index (control = 62%, 0.03µM = 41%, 0.1 µM = 32%, 0.3 µM = 16%; p < 0.05) progressively decreased on increasing the GS967 concentration. CONCLUSIONS: GS967 attenuates stretch-induced changes in cardiac electrophysiology.

Chronic exercise impairs nitric oxide pathway in rabbit carotid and femoral arteries.

KEY POINTS: Some of the beneficial effects of exercise in preventing vascular related diseases are mediated by the enhancement of endothelial function where the role of nitric oxide (NO) is well documented, although the relevance of calcium activated potassium channels is not fully understood. The impact of oxidative stress induced by training on endothelial function remains to be clarified. By evaluating different endothelial vasodilator pathways on two vascular beds in a rabbit model of chronic exercise, we found a decreased NO bioavailability and endothelial nitric oxide synthase expression in both carotid and femoral arteries. Physical training induced carotid endothelial dysfunction as a result of an increase in oxidative stress and a reduction in superoxide dismutase expression. In the femoral artery, the lower production of NO was counteracted by an increased participation of large conductance calcium activated potassium channels, preventing endothelial dysfunction. ABSTRACT: The present study aimed to evaluate the effects of chronic exercise on vasodilator response in two different arteries. Rings of carotid and femoral arteries from control and trained rabbits were suspended in organ baths for isometric recording of tension. Endothelial nitric oxide synthase (eNOS), Cu/Zn and Mn-superoxide dismutase (SOD), and large conductance calcium activated potassium (BKCa) channel protein expression were measured by western blotting. In the carotid artery, training reduced the relaxation to ACh (10-9 to 3 × 10-6  m) that was reversed by N-acetylcysteine (10-3  m). l-NAME (10-4  m) reduced the relaxation to ACh in both groups, although the effect was lower in the trained group (in mean ± SEM, 39 ± 2% vs. 28 ± 3%). Physical training did not modify the relaxation to ACh in femoral arteries, although the response to l-NAME was lower in the trained group (in mean ± SEM, 41 ± 5% vs. 17 ± 2%). Charybdotoxin (10-7  m) plus apamin (10-6  m) further reduced the maximal relaxation to ACh only in the trained group. The remaining relaxation in both carotid and femoral arteries was abolished by KCl (2 × 10-2  m) and BaCl2 (3 × 10-6  m) plus ouabain (10-4  m) in both groups. Physical training decreased eNOS expression in both carotid and femoral arteries and Cu/Zn and Mn-SOD expression only in the carotid artery. BKCa channels were overexpressed in the trained group in the femoral artery. In conclusion, chronic exercise induces endothelial dysfunction in the carotid artery as a result of oxidative stress. In the femoral artery, it modifies the vasodilator pathways, enhancing the participation of BKCa channels, thus compensating for the impairment of NO-mediated vasodilatation.

Effects of S-Nitrosoglutathione on Electrophysiological Manifestations of Mechanoelectric Feedback.

Electromechanical coupling studies have described the intervention of nitric oxide and S-nitrosylation processes in Ca2+ release induced by stretch, with heterogeneous findings. On the other hand, ion channel function activated by stretch is influenced by nitric oxide, and concentration-dependent biphasic effects upon several cellular functions have been described. The present study uses isolated and perfused rabbit hearts to investigate the changes in mechanoelectric feedback produced by two different concentrations of the nitric oxide carrier S-nitrosoglutathione. Epicardial multielectrodes were used to record myocardial activation at baseline and during and after left ventricular free wall stretch using an intraventricular device. Three experimental series were studied: (a) control (n = 10); (b) S-nitrosoglutathione 10 µM (n = 11); and (c) S-nitrosoglutathione 50 µM (n = 11). The changes in ventricular fibrillation (VF) pattern induced by stretch were analyzed and compared. S-nitrosoglutathione 10 µM did not modify VF at baseline, but attenuated acceleration of the arrhythmia (15.6 ± 1.7 vs. 21.3 ± 3.8 Hz; p < 0.0001) and reduction of percentile 5 of the activation intervals (42 ± 3 vs. 38 ± 4 ms; p < 0.05) induced by stretch. In contrast, at baseline using the 50 µM concentration, percentile 5 was shortened (38 ± 6 vs. 52 ± 10 ms; p < 0.005) and the complexity index increased (1.77 ± 0.18 vs. 1.27 ± 0.13; p < 0.0001). The greatest complexity indices (1.84 ± 0.17; p < 0.05) were obtained during stretch in this series. S-nitrosoglutathione 10 µM attenuates the effects of mechanoelectric feedback, while at a concentration of 50 µM the drug alters the baseline VF pattern and accentuates the increase in complexity of the arrhythmia induced by myocardial stretch.

Effects of JTV-519 on stretch-induced manifestations of mechanoelectric feedback.

JTV-519 is a 1,4-benzothiazepine derivative with multichannel effects that inhibits Ca2+ release from the sarcoplasmic reticulum and stabilizes the closed state of the ryanodine receptor, preventing myocardial damage and the induction of arrhythmias during Ca2+ overload. Mechanical stretch increases cellular Na+ inflow, activates the reverse mode of the Na+ /Ca2+ exchanger, and modifies Ca2+ handling and myocardial electrophysiology, favoring arrhythmogenesis. This study aims to determine whether JTV-519 modifies the stretch-induced manifestations of mechanoelectric feedback. The ventricular fibrillation (VF) modifications induced by acute stretch were studied in Langendorff-perfused rabbit hearts using epicardial multiple electrodes under control conditions (n=9) or during JTV-519 perfusion: 0.1 µmol/L (n=9) and 1 µmol/L (n=9). Spectral and mapping techniques were used to establish the baseline, stretch and post-stretch VF characteristics. JTV-519 slowed baseline VF and decreased activation complexity. These effects were dose-dependent (baseline VF dominant frequency: control=13.9±2.2 Hz; JTV 0.1 µmol/L=11.1±1.1 Hz, P<.01; JTV 1 µmol/L=6.6±1.1 Hz, P<.0001). The stretch-induced acceleration of VF (control=38.8%) was significantly reduced by JTV-519 0.1 µmol/L (19.8%) and abolished by JTV 1 µmol/L (-1.5%). During stretch, the VF activation complexity index was reduced in both JTV-519 series (control=1.60±0.15; JTV 0.1 µmol/L=1.13±0.3, P<.0001; JTV 1 µmol/L=0.57±0.21, P<.0001), and was independently related to VF dominant frequency (R=.82; P<.0001). The fifth percentile of the VF activation intervals, conduction velocity and wavelength entered the multiple linear regression model using dominant frequency as the dependent variable (R=-.84; P<.0001). In conclusion, JTV-519 slowed and simplified the baseline VF activation patterns and abolished the stretch-induced manifestations of mechanoelectric feedback.

Estudio experimental de los efectos de EIPA, losartán y BQ-123 sobre las modificaciones electrofisiológicas inducidas por el estiramiento miocárdico / Experimental study of the effects of EIPA, Losartan, and BQ-123 on electrophysiological changes induced by myocardial stretch

Introducción y objetivos: Se han implicado diversos mecanismos en la respuesta mecánica al estiramiento miocárdico, que incluyen la activación del intercambiador Na+/H+ por acciones autocrinas y paracrinas. Se estudia la participación de estos mecanismos en las respuestas electrofisiológicas al estiramiento agudo miocárdico mediante el análisis de los cambios inducidos con fármacos. Métodos: Se analizan las modificaciones de la fibrilación ventricular inducidas por el estiramiento agudo miocárdico en corazones de conejo aislados y perfundidos utilizando electrodos múltiples epicárdicos y técnicas cartográficas. Se estudian 4 series: control (n = 9); durante la perfusión del antagonista de los receptores de la angiotensina II, losartán (1 miM, n = 8); durante la perfusión del bloqueador del receptor de la endotelina A, BQ-123 (0,1 miM, n = 9), y durante la perfusión del inhibidor del intercambiador Na+/H+, EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 miM, n = 9). Resultados: EIPA atenuó el aumento de la frecuencia dominante de la fibrilación producido por el estiramiento (control = 40,4%; losartán = 36% [no significativo]; BQ-123 = 46% [no significativo], y EIPA = 22% [p < 0,001]). Durante el estiramiento, la complejidad de los mapas de activación fue menor en la serie con EIPA (p < 0,0001) y también en esta serie fue mayor la concentración espectral de la arritmia (mayor regularidad): control = 18 ± 3%; EIPA = 26 ± 9% (p < 0,02); losartán = 18 ± 5% (no significativo), y BQ-123 = 18 ± 4% (no significativo). Conclusiones: El inhibidor del intercambiador Na+/H+ EIPA atenúa los efectos electrofisiológicos responsables de la aceleración y del aumento de la complejidad de la fibrilación ventricular producidos por el estiramiento agudo miocárdico. Por el contrario, el antagonista de los receptores de la angiotensina II, losartán, y el del receptor A de la endotelina, BQ-123, no modifican estos efectos (AU)

Introduction and objectives: Mechanical response to myocardial stretch has been explained by various mechanisms, which include Na+ /H+ exchanger activation by autocrine-paracrine system activity. Drug-induced changes were analyzed to investigate the role of these mechanisms in the electrophysiological responses to acute myocardial stretch. Methods: Multiple epicardial electrodes and mapping techniques were used to analyze changes in ventricular fibrillation induced by acute myocardial stretch in isolated perfused rabbit hearts. Four series were studied: control (n = 9); during perfusion with the angiotensin receptor blocker losartan (1 mM, n = 8); during perfusion with the endothelin A receptor blocker BQ-123 (0.1 mM, n = 9), and during perfusion with the Na+ /H+ exchanger inhibitor EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 mM, n = 9). Results: EIPA attenuated the increase in the dominant frequency of stretch-induced fibrillation (control = 40.4%; losartan = 36% [not significant]; BQ-123 = 46% [not significant]; and EIPA = 22% [P < .001]). During stretch, the activation maps were less complex (P < .0001) and the spectral concentration of the arrhythmia was greater (greater regularity) in the EIPA series: control = 18 (3%); EIPA = 26 (9%) (P < .02); losartan = 18 (5%) (not significant); and BQ-123 = 18 (4%) (not significant). Conclusions: The Na+ /H+ exchanger inhibitor EIPA attenuated the electrophysiological effects responsible for the acceleration and increased complexity of ventricular fibrillation induced by acute myocardial stretch. The angiotensin II receptor antagonist losartan and the endothelin A receptor blocker BQ-123 did not modify these effects (AU)

Estrategias de educación médica continua / Continuing medical education strategies

Para ejercer apropiadamente a lo largo de su vida profesional, los médicos han de involucrarse en alguna forma de educación continua. La educación médica continua no se limita a la educación formal desarrollada mediante tal o cual método educativo, sino que comprende experiencias de muy diversa índole, formales e informales, tales como los encuentros con colegas, el autoaprendizaje y la educación a distancia. El propósito de esta publicación es presentar los resultados obtenidos al explorar las estrategias y recursos mas frecuentemente utilizados por los profesionales médicos para mantenerse actualizados. Se implementó una encuesta electrónica de cinco preguntas cerradas con varias opciones de respuesta. Las preguntas indagaban sobre: lugar de trabajo, frecuencia con la que experimenta ‘necesidad’ de actualizar sus conocimientos, modalidades y recursos utilizados. Se obtuvieron 9.851 respuestas. Las modalidades más frecuentemente mencionadas fueron asistencia a cursos presenciales, a congresos y seminarios, y participación en actividades hospitalarias. Las revistas publicadas por sociedades científicas y las guías clínicas son las fuentes de información señaladas con mayor frecuencia. Los recursos disponibles en Internet fueron mencionados por menos del 20% de los profesionales que respondieron. Se encontraron algunas diferencias entre las modalidades y recursos que utilizan los médicos que trabajan sólo en su consulta y los que atienden en un hospital

To properly exercise throughout his professional life, doctors have to engage in some form of continuing education. Continuing medical education is not limited to formal education, includes very diverse experiences, formal and informal such as meetings with colleagues, self-learning and distance education. The purpose of this paper is to present the results to explore strategies and resources used by medical professionals to keep up to date. Implemented an electronic survey of 5 questions with several response options; explored questions about: workplace, frequency experiences ‘need’ to update their medical knowledge, methods and resources used more frequently. 9.851 answers were obtained. The most frequently mentioned modalities were assistance to courses, conferences and seminars and participating in activities in the hospital. Journals published by scientific societies and clinical guidelines are information sources referred to most frequently. The resources available on the internet were mentioned by less than 20% of the professionals who responded. There are some differences between the methods and resources used by doctors who work only in their offices and those who attend at hospital

Ranolazine Attenuates the Electrophysiological Effects of Myocardial Stretch in Langendorff-Perfused Rabbit Hearts.

PURPOSE: Mechanical stretch is an arrhythmogenic factor found in situations of cardiac overload or dyssynchronic contraction. Ranolazine is an antianginal agent that inhibits the late Na (+) current and has been shown to exert a protective effect against arrhythmias. The present study aims to determine whether ranolazine modifies the electrophysiological responses induced by acute mechanical stretch. METHODS: The ventricular fibrillation modifications induced by acute stretch were studied in Langendorff-perfused rabbit hearts using epicardial multiple electrodes under control conditions (n = 9) or during perfusion of the late Na(+) current blocker ranolazine 5 µM (n = 9). Spectral and mapping techniques were used to establish the ventricular fibrillation dominant frequency, the spectral concentration and the complexity of myocardial activation in three situations: baseline, stretch and post-stretch. RESULTS: Ranolazine attenuated the increase in ventricular fibrillation dominant frequency produced by stretch (23.0 vs 40.4 %) (control: baseline =13.6 ± 2.6 Hz, stretch = 19.1 ± 3.1 Hz, p < 0.0001; ranolazine: baseline = 1.4 ± 1.8 Hz, stretch =14.0 ± 2.4 Hz, p < 0.05 vs baseline, p < 0.001 vs control). During stretch, ventricular fibrillation was less complex in the ranolazine than in the control series, as evaluated by the lesser percentage of complex maps and the greater spectral concentration of ventricular fibrillation. These changes were associated to an increase in the fifth percentile of VV intervals during ventricular fibrillation (50 ± 8 vs 38 ± 5 ms, p < .01) and in the wavelength of the activation (2.4 ± 0.3 vs 1.9 ± 0.2 cm, p < 0.001) under ranolazine. CONCLUSIONS: The late inward Na(+) current inhibitor ranolazine attenuates the electrophysiological effects responsible for the acceleration and increase in complexity of ventricular fibrillation produced by myocardial stretch.

Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch.

INTRODUCTION AND OBJECTIVES: Mechanical response to myocardial stretch has been explained by various mechanisms, which include Na(+)/H(+) exchanger activation by autocrine-paracrine system activity. Drug-induced changes were analyzed to investigate the role of these mechanisms in the electrophysiological responses to acute myocardial stretch. METHODS: Multiple epicardial electrodes and mapping techniques were used to analyze changes in ventricular fibrillation induced by acute myocardial stretch in isolated perfused rabbit hearts. Four series were studied: control (n = 9); during perfusion with the angiotensin receptor blocker losartan (1 µM, n = 8); during perfusion with the endothelin A receptor blocker BQ-123 (0.1 µM, n = 9), and during perfusion with the Na(+)/H(+) exchanger inhibitor EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 µM, n = 9). RESULTS: EIPA attenuated the increase in the dominant frequency of stretch-induced fibrillation (control=40.4%; losartan=36% [not significant]; BQ-123=46% [not significant]; and EIPA=22% [P<.001]). During stretch, the activation maps were less complex (P<.0001) and the spectral concentration of the arrhythmia was greater (greater regularity) in the EIPA series: control=18 (3%); EIPA = 26 (9%) (P < .02); losartan=18 (5%) (not significant); and BQ-123=18 (4%) (not significant). CONCLUSIONS: The Na(+)/H(+) exchanger inhibitor EIPA attenuated the electrophysiological effects responsible for the acceleration and increased complexity of ventricular fibrillation induced by acute myocardial stretch. The angiotensin II receptor antagonist losartan and the endothelin A receptor blocker BQ-123 did not modify these effects.

Evaluación del ambiente educacional en residencias de cardiología / Assessment of Educational Environment in Cardiology Residencies

Introducción: El "ambiente educacional", producto del ambiente físico, de las relaciones interpersonales, de los factores estresantes y del sistema de reconocimientos y sanciones, entre otros, influye en la motivación de los estudiantes, en la disposición hacia el estudio y en el rendimiento académico. La evaluación del ambiente educacional se focaliza en la percepción que los estudiantes tienen del contexto más allá de lo que podría ser apreciado "objetivamente" por un observador externo. Objetivo: Presentar los resultados obtenidos de la aplicación de una versión local del cuestionario PHEEM a residentes de cardiología para explorar si la percepción de los residentes es diferente según la condición pública o privada del servicio hospitalario. Material y métodos: Se utilizó el cuestionario PHEEM (Postgraduate Hospital Educational Environment Measure), desarrollado por S. Roff, S. McAleer y A. Skinner, el cual es un instrumento específico para evaluar el ambiente educacional en el contexto hospitalario. Resultados: Respondieron 148 residentes de 31 hospitales diferentes de la Ciudad de Buenos Aires y el Conurbano Bonaerense, asistentes al Curso Bienal de Cardiología en 2012: 71 residentes de hospitales públicos, 75 de hospitales privados y 2 no identificaron la condición del hospital. Se encontraron diferencias significativas que indicarían mejores condiciones para el aprendizaje en las residencias privadas. Las diferencias se refieren a la disponibilidad de supervisión, a las instalaciones sanitarias y sala de reuniones/descanso para los médicos de guardia, a la sensación de seguridad física dentro del hospital y a la cantidad de consultas y de estudios suficientes para el aprendizaje. No se registraron discrepancias en cuanto al alto nivel de exigencia, al escaso feedback y a la falta de tiempo "protegido" para estudiar dentro del horario de trabajo semanal. Conclusión: Sería necesario evaluar residencias de otras especialidades y en otras jurisdicciones para analizar si se trata de una conclusión general o si aplica solo a la especialidad cardiología en el área metropolitana.

Introduction: The "educational environment", which is the combined result of physical environment, interpersonal relations, stressing factors and the reward and penalty system, among others, influences student motivation, readiness to study and academic achievement. Educational environment assessment focuses on student perception of the context beyond what might be "objectively" appreciated by an external observer. Objective: The aim of this study is to present results obtained from the application of a local version of the PHEEM questionnaire to cardiology residents to explore whether their perception differs according to hospital public or private condition. Methods: We applied the PHEEM (Postgraduate Hospital Educational Environment Measure) questionnaire, developed by S. Roff, S. McAleer and A. Skinner, which is a specific tool to assess educational environment in the hospital setting. Results: One hundred and forty eight residents from 31 Buenos Aires City and Greater Buenos Aires hospitals, who attended the 2012 Biennial Cardiology Course, completed the questionnaire: 71 residents from public hospitals, 75 from private hospitals and 2 who did not identify hospital condition. Private hospital residencies showed significantly better learning conditions. Differences were found in supervision availability, sanitation facilities and resting / meeting rooms for doctors on call, the sense of physical security inside the hospital and the adequate number of patients and studies for learning. There were no differences regarding the high level of exigency, poor feedback and lack of "protected" time to study during working week hours. Conclusions: It would be necessary to evaluate other specialty residencies and programs implemented in other jurisdictions, to analyze whether this is a general conclusion or it only applies to cardiology residencies in the metropolitan area.

Evaluación del ambiente educacional en residencias de cardiología / Assessment of Educational Environment in Cardiology Residencies

Introducción: El "ambiente educacional", producto del ambiente físico, de las relaciones interpersonales, de los factores estresantes y del sistema de reconocimientos y sanciones, entre otros, influye en la motivación de los estudiantes, en la disposición hacia el estudio y en el rendimiento académico. La evaluación del ambiente educacional se focaliza en la percepción que los estudiantes tienen del contexto más allá de lo que podría ser apreciado "objetivamente" por un observador externo. Objetivo: Presentar los resultados obtenidos de la aplicación de una versión local del cuestionario PHEEM a residentes de cardiología para explorar si la percepción de los residentes es diferente según la condición pública o privada del servicio hospitalario. Material y métodos: Se utilizó el cuestionario PHEEM (Postgraduate Hospital Educational Environment Measure), desarrollado por S. Roff, S. McAleer y A. Skinner, el cual es un instrumento específico para evaluar el ambiente educacional en el contexto hospitalario. Resultados: Respondieron 148 residentes de 31 hospitales diferentes de la Ciudad de Buenos Aires y el Conurbano Bonaerense, asistentes al Curso Bienal de Cardiología en 2012: 71 residentes de hospitales públicos, 75 de hospitales privados y 2 no identificaron la condición del hospital. Se encontraron diferencias significativas que indicarían mejores condiciones para el aprendizaje en las residencias privadas. Las diferencias se refieren a la disponibilidad de supervisión, a las instalaciones sanitarias y sala de reuniones/descanso para los médicos de guardia, a la sensación de seguridad física dentro del hospital y a la cantidad de consultas y de estudios suficientes para el aprendizaje. No se registraron discrepancias en cuanto al alto nivel de exigencia, al escaso feedback y a la falta de tiempo "protegido" para estudiar dentro del horario de trabajo semanal. Conclusión: Sería necesario evaluar residencias de otras especialidades y en otras jurisdicciones para analizar si se trata de una conclusión general o si aplica solo a la especialidad cardiología en el área metropolitana.(AU)

Introduction: The "educational environment", which is the combined result of physical environment, interpersonal relations, stressing factors and the reward and penalty system, among others, influences student motivation, readiness to study and academic achievement. Educational environment assessment focuses on student perception of the context beyond what might be "objectively" appreciated by an external observer. Objective: The aim of this study is to present results obtained from the application of a local version of the PHEEM questionnaire to cardiology residents to explore whether their perception differs according to hospital public or private condition. Methods: We applied the PHEEM (Postgraduate Hospital Educational Environment Measure) questionnaire, developed by S. Roff, S. McAleer and A. Skinner, which is a specific tool to assess educational environment in the hospital setting. Results: One hundred and forty eight residents from 31 Buenos Aires City and Greater Buenos Aires hospitals, who attended the 2012 Biennial Cardiology Course, completed the questionnaire: 71 residents from public hospitals, 75 from private hospitals and 2 who did not identify hospital condition. Private hospital residencies showed significantly better learning conditions. Differences were found in supervision availability, sanitation facilities and resting / meeting rooms for doctors on call, the sense of physical security inside the hospital and the adequate number of patients and studies for learning. There were no differences regarding the high level of exigency, poor feedback and lack of "protected" time to study during working week hours. Conclusions: It would be necessary to evaluate other specialty residencies and programs implemented in other jurisdictions, to analyze whether this is a general conclusion or it only applies to cardiology residencies in the metropolitan area.(AU)

Evaluación de la complejidad de la activación miocárdica durante la fibrilación ventricular. Estudio experimental / Evaluation of the complexity of myocardial activation during ventricular fibrillation. An experimental study

Introducción y objetivos. Analizar en un modelo experimental las características de la fibrilación ventricular en situaciones con distintos grados de complejidad y establecer la relación existente entre los datos aportados por distintos métodos de análisis de la arritmia. Métodos. En 27 preparaciones de corazón aislado de conejo estudiadas bajo la acción de fármacos (propranolol y KB-R7943) o procedimientos físicos (estiramiento) que causan distintos grados de variación de la complejidad de la activación miocárdica durante la arritmia, se han utilizado técnicas espectrales, morfológicas y cartográficas para procesar los registros obtenidos con multielectrodos epicárdicos. Resultados. La complejidad de la fibrilación ventricular objetivada mediante procedimientos cartográficos se ha relacionado con la frecuencia dominante, la energía normalizada del espectro, el índice de regularidad de las señales, sus coeficientes de variación y el área de las regiones de interés identificadas a partir de estos parámetros. En el análisis multivariable, se han aceptado como variables independientes el área de las regiones de interés relacionadas con la energía espectral y el coeficiente de variación de la energía (índice de complejidad = -0,005 × área de las regiones de la energía espectral -2,234 × coeficiente de variación de la energía +1,578; p = 0,0001; r = 0,68). Conclusiones. Los indicadores espectrales, morfológicos y, de manera independiente, los derivados del análisis de las regiones de interés de la energía normalizada permiten aproximarse de manera fiable a la evaluación de la complejidad de la fibrilación ventricular como una alternativa a los complejos procedimientos cartográficos (AU)

Introduction and objectives. An experimental model is used to analyze the characteristics of ventricular fibrillation in situations of variable complexity, establishing relationships among the data produced by different methods for analyzing the arrhythmia. Methods. In 27 isolated rabbit heart preparations studied under the action of drugs (propranolol and KB-R7943) or physical procedures (stretching) that produce different degrees of change in the complexity of myocardial activation during ventricular fibrillation, use was made of spectral, morphological, and mapping techniques to process the recordings obtained with epicardial multielectrodes. Results. The complexity of ventricular fibrillation assessed by mapping techniques was related to the dominant frequency, normalized spectral energy, signal regularity index, and their corresponding coefficients of variation, as well as the area of the regions of interest identified on the basis of these parameters. In the multivariate analysis, we used as independent variables the area of the regions of interest related to the spectral energy and the coefficient of variation of the energy (complexity index = -0.005 × area of the spectral energy regions -2.234 × coefficient of variation of the energy +1.578; P=.0001; r=0.68). Conclusions. The spectral and morphological indicators and, independently, those derived from the analysis of normalized energy regions of interest provide a reliable approach to the evaluation of the complexity of ventricular fibrillation as an alternative to complex mapping techniques (AU)

Evaluation of the complexity of myocardial activation during ventricular fibrillation. An experimental study.

INTRODUCTION AND OBJECTIVES: An experimental model is used to analyze the characteristics of ventricular fibrillation in situations of variable complexity, establishing relationships among the data produced by different methods for analyzing the arrhythmia. METHODS: In 27 isolated rabbit heart preparations studied under the action of drugs (propranolol and KB-R7943) or physical procedures (stretching) that produce different degrees of change in the complexity of myocardial activation during ventricular fibrillation, use was made of spectral, morphological, and mapping techniques to process the recordings obtained with epicardial multielectrodes. RESULTS: The complexity of ventricular fibrillation assessed by mapping techniques was related to the dominant frequency, normalized spectral energy, signal regularity index, and their corresponding coefficients of variation, as well as the area of the regions of interest identified on the basis of these parameters. In the multivariate analysis, we used as independent variables the area of the regions of interest related to the spectral energy and the coefficient of variation of the energy (complexity index=-0.005×area of the spectral energy regions -2.234×coefficient of variation of the energy+1.578; P=.0001; r=0.68). CONCLUSIONS: The spectral and morphological indicators and, independently, those derived from the analysis of normalized energy regions of interest provide a reliable approach to the evaluation of the complexity of ventricular fibrillation as an alternative to complex mapping techniques.

Escolas traçadas com régua e compasso na Colômbia e no Brasil / Schools drawn with a ruler and a compass in Colombia and Brazil

Com este artigo, que é parte de uma pesquisa mais ampla, pretendemos refletir sobre o processo de escolarização da infância, em duas revistas destinadas à formação de professores para o magistério. Ambas produzidas por grupos articulados a políticas educacionais e divulgadas para as redes públicas de ensino de São Paulo (Brasil) e outra para Bogotá (Colômbia), de 1932 a 1939. Fizemos duas perguntas às revistas: O que podem nos dizer sobre as finalidades políticas da formação de professores para o magistério? E sobre as relações entre os métodos científicos da psicologia e da pedagogia? No final, apresentamos nossas suspeitas de cumplicidade entre projetos pedagógicos e projetos políticos autoritários, atuando no conjunto das forças cognitivas, psicológicas, culturais e institucionais.

Escolas traçadas com régua e compasso na colômbia e no brasil / Schools drawn with a ruler and a compass in Colombia and Brazil

RESUMO: Com este artigo, que é parte de uma pesquisa mais ampla, pretendemos refletir sobre o processo de escolarização da infância, em duas revistas destinadas à formação de professores para o magistério. Ambas produzidas por grupos articulados a políticas educacionais e divulgadas para as redes públicas de ensino de São Paulo (Brasil) e outra para Bogotá (Colômbia), de 1932 a 1939. Fizemos duas perguntas às revistas: O que podem nos dizer sobre as finalidades políticas da formação de professores para o magistério? E sobre as relações entre os métodos científicos da psicologia e da pedagogia? No final, apresentamos nossas suspeitas de cumplicidade entre projetos pedagógicos e projetos políticos autoritários, atuando no conjunto das forças cognitivas, psicológicas, culturais e institucionais. (AU)

Un caso de manía orgánica, diagnóstico diferencial / A case of organic mania, differential diagnosis

Presentamos el caso de una paciente de 74 años con antecedentes de síndrome depresivo que ingresa en el servicio de psiquiatría por un cuadro maníaco en principio relacionado con un hipotiroidismo severo al dejar de tomar levotiroxina. Unos meses después la paciente ingresó en el servicio de medicina interna por disnea, artritis, úlceras bucales así como hipocomplementemia y elevación de ANA. Revisando la historia clínica de la paciente observamos que antes del brote maníaco la paciente tenía datos clínicos que indicaban actividad lúpica. Es importante identificar los síntomas neuropsiquiátricos en una paciente con lupus, ya que pueden ser la manifestación de inicio de la enfermedad en contraposición a un trastorno afectivo primario. Existen muy pocos casos descritos de psicosis secundaria a un hipotiroidismo aunque la relación entre los trastornos tiroideos y el lupus eritematoso sistémico no es tan rara (AU)

We present a case of a 74 year-old woman with a history of depression who was admitted to the psychiatric department due to having a maniacal clinical picture associated with a severe hypothyroidism on stopping taking levothyroxine. A few months later the patient was admitted to the internal medicine department because of dyspnea, arthritis, mouth ulcers and a low complement and increased ANA. Reviewing the history of the patient before the outbreak we observed that the patient had a clinical history showing lupus activity. It is important to identify neuropsychiatric symptoms in a patient with lupus, as they could be the initial onset of the illness as opposed to a primary affective disorder. There are very few cases of psychosis secondary to hypothyroidism, although the relationship between thyroid disorders and systemic lupus erythematosus is not so rare (AU)

Efecto de la suplementación con hierro sobre el zinc en sangre y en orina, en mujeres gestantes: estudio preliminar / Effect of iron supplementation on blood and urinary zinc in a group of pregnant women: preliminary study

Se evaluó el efecto de la suplementación con Fe sobre la variación del Zn sanguíneo y urinario en 36 mujeres, clínicamente sanas, atendidas durante la gestación en el Hospital D. Paroissien (La Matanza, Buenos Aires). A la primera consulta (To) (edad gestacional: 17 ± 3 semanas) se realizó una encuesta de recordatorio de 24 hs., calculando la ingesta de Zn (lZn); se determinó en sangre entera, extraída en ayunas: Zn (ZnS) (espectrofotometría de absorción atómica, EAA) y Hemoglobina (Hb); en suero: ferritina (ELISA); en orina basal (la segunda de la mañana, con ayuno de líquidos y sólidos): Zn (EAA) y Creatinina (Crea), método de Jaffé. Las gestantes con Hb < 11 g/dL y aquellas con Hb > 11 g/dL, pero con ferritina < 12 ng/mL (Gfe, n =13) recibieron 100 mg/día de Fe (maltosato férrico); las mujeres con Hb > 11 g/dL y ferritina > 12 ng/mL constituyeron el grupo control (GC, n = 23). A las semanas 26 ± 2 (T1) y 35 ± 2 (Tf) se repitieron las determinaciones de laboratorio. Los promedios ± DE fueron, para GC y GFe, respectivamente: To: lZn (mg/día): 5,7 ± 2,3; 6,6 ± 4,2 (ns); Hb (g/dL):12,4 ± 0,9; 11,0 ± 1,0 (p<0,05); ferritina (ng/mL): 100 ± 81; 54 ± 40 (p <0,05); ZnS (mg/d/L): 528 ± 81; 545 ± 116; Zn/Crea (mg/g): 0,53 ± 0,34; 0,42 ± 0,33; T1; Hb(g/dL): 11,1 ± 1,3; 10,0 ± 1,4; ferritina }(ng/mL): 106 ± 108; 11 ± 3 (p < 0,05); ZnS (ug/dl): 506 ± 77; 517 ± 111; Zn/Crea (mg/g): 0,52 ± 0,16; 0,48 ± 0,23; Tf: Hb (g/dL): 10,5 ± 1,5; 10,5 ± 1,3; ferritina (ng/mL): 16 ± 12; 14 ± 9 (ns); ZnS (mg/dl): 569 ± 99; 545 ± 90; Zn/Crea (mg/g): 0,50 ± 0,10; 0,61 ± 0,29. No existieron diferencias significativas en ZnS ni en Zn/crea entre GC y GFe a To ni durante el estudio. Estos resultados indican que la administración de suplementos de Fe alejada de las comidas no afecta los niveles de Zn eritrocitario ni la eliminación urinaria basal durante la gestación en los rangos de ingesta de Zn del presente estudio.