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[ES] Varios grupos de investigación han propuesto distintos protocolos de registro electrocardiográfico de superficie no estándar para cuantificar de manera específica señales de Fibrilación Auricular (FA). Por lo tanto, surge la necesidad de validar dichos protocolos comparándolos con registros epicárdicos. En este sentido, el presente trabajo realiza una comparación prospectiva de cuatro de los protocolos de registro electrocardiográfico de superficie no estándar propuestos en la literatura. Mediante el uso de técnicas de procesado de señal, se han comparado registros superficiales de pacientes afectados de FA con registros invasivos de los mismos pacientes. El objetivo de este trabajo es comprobar cuál de los protocolos de registro superficial estudiados es capaz de estimar con mayor fidelidad y precisión parámetros que determinan la organización de la fibrilación auricular. Los parámetros analizados han sido la frecuencia dominante, la entropía muestral de la onda auricular principal y la potencia normalizada de las ondas fibrilatorias., [EN] Several research groups have proposed various non-standard ECG surface recording protocols to specifically quantify Atrial Fibrillation (AF) signals. For that reason, there is a need to compare these protocols against epicardial recordings. In this sense, this work makes a prospective comparison of four non-standard ECG surface recording protocols proposed in the literature. Using signal processing techniques, this study compares body surface recordings of AF's patients with invasive recordings of the same patients. The aim of this study is to assess which of the non-standard surface protocol is able to estimate with greater fidelity and accuracy parameters determining AF organization. The analyzed parameters were the dominant frequency, sample entropy of the main atrial wave and the normalized power of fibrillatory waves.

La posible asociación entre el desarrollo de fibrilación auricular (FA) con la presencia de cardiopatía chagásica en una población portadora de dispositivos cardiacos de estimulación no está descrita. Se presenta un estudio de tipo cohorte retrospectivo realizado en la FCI que recopila las principales características clínicas de una población de pacientes con cardiopatía de variada etiología y portadores de dispositivos cardiacos buscando evaluar la incidencia de FA en presencia de cardiomiopatía de origen chagásico y no chagásico. A la fecha no se cuenta con una base de datos institucional ni regional que contenga las variables analizadas. Durante los 5 meses que duró la construcción de la base de datos se incluyeron 99 sujetos de investigación. Se implantaron 42 marcapasos bicamerales, 39 cardiodesfibriladores bicamerales, 6 dispositivos correspondientes cardiodesfibrilador con función de resincronización cardiaca, 2 resincronizadores cardiacos sin función de cardiodesfibrilador y 7 cardiodesfibriladores unicamerales. De los 99 sujetos recolectados se presentaron 8 desenlaces (FA de novo) y de esos solamente 1 pertenece al grupo de pacientes con cardiomiopatía chagásica. Este número reducido de desenlaces no permitió desarrollar un modelo de regresión de Cox y ni otros tipos de análisis estadísticos planteados en el protocolo inicial debido al bajo número de casos y pobre poder estadístico. Esta dificultad es inherente a la naturaleza del problema a estudiar y al corto tiempo de seguimiento. Por lo anterior no se puede establecer si existe una relación entre la presencia de serología positiva para infección por T. Cruzi y la presencia de FA de novo. The association between atrial fibrillation (AF) development in presence of Chagas heart disease in a population carrying cardiac stimulation devices has not been described. We present a retrospective cohort study conducted at the FCI that collects the main clinical features of a population with heart disease of varied etiology and carriers of cardiac stimulation devices seeking to assess the incidence of AF in patients with Chagas cardiomyopathy. To date there is not a regional or institutional database that contains variables analyzed here. During the 5 months of the construction of the database we included 99 research subjects. We implanted forty two dual chamber pacemakers, thirty nine bicameral defibrillators, six defibrillators with cardiac resynchronization function, two cardiac resynchronization devices without defibrillator function and seven unicameral defibrillators. Of the 99 subjects collected 8 presented the main outcome (AF) and of those only 1 belongs to the group of patients with Chagas cardiomyopathy. The small number of outcomes makes not possible to develop a regression model of Cox and or other types of statistical analyzes raised in the initial protocol due to the low number of cases and low statistical power. This difficulty is due to the pathology itself and the short follow-up time. Therefore it can not be set if there is a relationship between the presence of positive T. Cruzi serology and the presence of AF.

Als eine der ersten chirurgischen Therapieverfahren zur Behandlung chronischen Vorhofflimmerns zeigte die Cox-Maze-III-Technik große Erfolgsraten, hatte jedoch eine hohe Invasivität. Neue Ablationsverfahren mit alternativen Energieformen, wie Mikrowellen- und Radiofrequenzenergie zeigen eine geringe Invasivität und können aufgrund ihrer schnellen Durchführbarkeit begleitend zu einem kardiochirurgischen Eingriff durchgeführt werden. Obwohl sich die linksatriale endokardiale Vorhofablation in vielen Krankenhäusern als Standardverfahren zur Therapie persistierenden Vorhofflimmerns etabliert hat sollte in dieser Arbeit genauer analysiert werden, welche präoperativen Parameter einen signifikanten Einfluss auf die Sinus-Rhythmus- Konversion haben. Inhalt dieser Arbeit war vorrangig die Analyse der präoperativ erhobenen Vorhofflimmerfrequenz und dessen Einfluss auf den Erfolg der Ablation persistierenden Vorhofflimmerns. Von August 2004 bis Dezember 2005 wurde bei 83 Patienten mit persistierendem Vorhofflimmern ein präoperatives Oberflächen-EKG mit Cardiolink® System zur Analyse der fibrillatorischen Aktivität durchgeführt. Die gespeicherten Daten wurden zu einem späteren Zeitpunkt analysiert, wobei durch eine QRST-Subtraktion und eine schnelle Fourier Transformation die reine fibrillatorische Aktivität als Vorhofflimmerfrequenz in Hz angegeben wurde. Es erfolgte eine Umrechung in fpm (fibrillations per minute). Alle Patienten wurden an der Klinik für kardiovaskuläre Chirurgie der Charité Campus Mitte in Berlin einer endokardialen linksatrialen Ablation begleitend zu einer Klappenund/ oder Bypassoperation zugeführt. Die Vorhofablation erfolgte mit Mikrowellenenergie (n = 29) (AFx ® Flex 4 der Firma Guidant GmbH & Co. Medizintechnik KG. Gießen) oder Radiofrequenzenergie (n = 54) (Cardioblate® der Firma Medtronic GmbH, Düsseldorf). Die Datenerfassung erfolgte präoperativ, peri- und postoperativ sowie in einer Nachuntersuchung nach 3, 6 und 12 Monaten. Es erfolgte eine Analyse des statistischen Zusammenhangs der Vorhofflimmerfrequenz mit weiteren präoperativen Parametern und des Einflusses der fibrillatorischen Aktivität auf die erfolgreiche Sinus-Rhythmus Konversion. Für die Diagnose Diabetes Mellitus (Diabetes Mellitus: 371,6 ± 55,1 bzw. kein Diabetes Mellitus: 396 ± 45,2, p = 0,03) und die antiarrhythmische Medikation (ohne antiarrhythmische Medikation: 349 fpm ± 81,6 bzw. mit antiarrhythmischer Medikation: 390 fpm ± 45,9, p = 0,05) zeigte sich ein statistisch signifikanter Zusammenhang mit der Vorhofflimmerfrequenz, der jedoch keine sinnvolle klinische Deutung ermöglichte. Es bestand ein Trend zur Signifikanz (382,5 ± 50,61 fpm bzw. 402,2 ± 39,99 fpm, p = 0,069) für den Einfluss der Vorhofflimmerfrequenz auf die erfolgreiche Vorhofablation. In einem weiteren univariaten Vergleich zwischen dem konvertierten und dem nichtkonvertierten Kollektiv zeigten die präoperativen Parameter Vorhofflimmerdauer (27,6 ± 35,83 (31) Monate bzw. 103,3 ± 126,10 (47,5) Monate, p = 0,002), systolische linksatriale Fläche (28,2 ± 8,66 cm² bzw. 33,3 ± 10,01 cm², p = 0,048) und der logistische Euroscore (7,2 ± 8,23 (35,7) bzw. 10,3 ± 8,73 (47,1), p = 0,036) signifikante Werte. Es zeigte sich kein signifikanter Unterschied (Konvertierte: RF 69,3%; MW: 30,7% bzw. nicht-Konvertierte RF: 61,5%; MW: 38,5% p = 0,612) für die beiden Ablationstechniken. In der multivariaten Analyse wurde die Vorhofflimmerdauer als einziger unabhängiger Prädiktor für die erfolgreiche Konversion in den Sinus- Rhythmus, mit einer Sensitivität von 94,6% und einer Spezifität von 36,8%, in die Berechnungen miteinbezogen. Für das errechnete Model zeigte sich eine signifikante Fläche von 0,735 ± 0,67 (p = 0,001) unter der ROC-Kurve (Konfidenzintervall 0,603 – 0,867) und der Hosmer-Lemeshow-Tests eine geringe Differenz zwischen beobachteten und erwarteten Werten (p = 0,136; χ² = 12,35). Zusammenfassend zeigte sich, dass die präoperative fibrillatorische Aktivität den Erfolg der Therapie persistierenden Vorhofflimmerns beeinflussen kann. In der univariaten Analyse zeigten sich der logistische Euroscore, die Fläche des Vorhofs und präoperative Vorhofflimmerdauer als die entscheidende Parameter für den Erfolg der kardiochirurgischen Therapie persistierenden Vorhofflimmerns, wobei in der multivariaten lediglich die Vorhofflimmerdauer als unabhängiger Prädiktor in die Berechnungen miteinbezogen wurde., xxxNew surgical ablation techniques with microwave and radiofrequency energy are less complex, as well as fast procedures which are increasingly being performed in conjunction with surgery for various heart diseases. We analysed the influence of the preoperative atrial fibrillatory frequency and other preoperative parameters on sinus rhythm conversion. From August 2004 to December 2005 the surface electrocardiogramms of 83 patients with persistent atrial fibrillation were recorded with the Cardiolink® System. After QRST cancellation, the frequency content of atrial fibrillation was identified by fast Fourier transformation. The results were calculated from Hz into fpm (fibrillations per minute). All patients were operated in the Clinic for Cardiovascular Surgery in Berlin and underwent concomitant left atrial ablation in conjunction with a cardiosurgical procedure. Ablation was performed by microwave (n = 29) or radiofrequency (n = 54) technology. Follow- up was after 3, 6, 12 months. There was a non-significant trend to a lower atrial fibrillatory frequency (382,5 ± 50,61 fpm; 402,2 ± 39,99 fpm, p = 0,069) for patients with a successful sinus rhythm conversion. The statistical analysis of converted (Sinus-Rhythm) and non-converted patients showed significant p-Values for preoperative atrial fibrillation duration (27,6 ± 35,83 (31) months; 103,3 ± 126,10 (47,5) months, p = 0,002), leftatrial systolic area (28,2 ± 8,66 cm²; 33,3 ± 10,01 cm², p = 0,048) and logistic EuroScore (7,2 ± 8,23 (35,7); 10,3 ± 8,73 (47,1), p = 0,036). Both energy sources had similar success rates for conversion into sinus-rhythm. The multivariate analysis showed preoperative atrial fibrillation duration as the only independent predictor for conversion into sinus rhythm (sensitivity: 94,6%; specificity: 36,8%) There was a significant area of 0,735 ± 0,67 (p = 0,001) under the ROC-Kurve (confidence interval 0,603 â�� 0,867) und the Hosmer-Lemeshow-Test showed a minor difference between observed and expected data (p = 0,136; Ï�² = 12,35). In conclusion, sinus rhythm restoration rate can be influenced by preoperative atrial fibrillatory frequency. In the univariate analysis the logistic Euroscore, systolic atrial area and preoperative atrial fibrillation duration showed significant p-values, whereas in the multivariate analysis only preoperative atrial fibrillation duration was an independent predictor for conversion into sinus rhythm.

RESUMEN La fibrilación auricular (FA) es la arritmia más frecuente en quienes consultan en las puertas de emergencia de nuestro medio, condición que se asocia a mayor carga de morbimortalidad y a una buena proporción del gasto sanitario. Existen dos estrategias terapéuticas, control de frecuencia o control de ritmo, ambas comparables en términos de complicaciones a corto y largo plazo. No obstante, existe evidencia a favor del control del ritmo. En este trabajo se presenta la experiencia de un servicio de asistencia prehospitalaria en el control de ritmo de casos seleccionados de FA de reciente instalación, con propafenona por vía oral. SUMMARY Atrial fibrillation (AF) is the most common arrhythmia in those assisted in an emergency department, a condition that is associated with greater burden of morbidity and a good proportion of health spending. There are two treatment strategies, rate control or rhythm control, both comparable in terms of complications in the short and long term. However, there is evidence that favors rhythm control. This paper presents the experience of a pre-hospital care service in controlling rhythm of selected AF cases with oral propafenone.

We sought to determine whether early postoperative conversion of AF to SR leads to restoration of atrial contractile function, as assessed by intraoperative velocity and deformation analysis. Restoration of atrial activation occurs in the early postoperative period, inducing atrial contraction. Nevertheless, this contraction occurs with low velocity and deformation both in patients with and without RFA, suggesting that, although atrial activation is restored, atrial mechanics do not recover in the early phase, potentially due to either atrial stunning or irreversible atrial structural remodeling.

O procedimento "labirinto" para o tratamento cirúrgico da fibrilação atrial (FA) proposto por Cox, para pacientes com FA, foi realizado entre julho de 1991 e maio de 1992, em nove pacientes, sendo sete do sexo feminino, com idade variando entre 37 e 63 anos (M = 51,4 anos). Oito pacientes tinham disfunções valvares reumáticas associadas (estenose mitral pura: seis pacientes; dupla disfunção mitral (DLM) um paciente e DLM e insuficiência trisúspide: um paciente). A FA foi classificada como crônica (mais de um ano de duração) de natureza reumática. Um paciente não tinha disfunção valvar associada e a FA foi considerada como paroxística recorrente refratária e não reumática. O procedimento cirúrgico foi realizado com o auxílio da circulação extracorpórea e consistiu na realização de múltiplas e previamente bem estabelecidas incisões nos átrios, de modo a tornar impossível a um impulso elétrico, originando-se em qualquer ponto dos átrios, retornar ao ponto de origem sem se deparar com uma linha de sutura. Isso impediria a ocorrência de reentrada em qualquer parte dos átrios. As múltiplas incisões são de tal foram realizadas que, adicionalmente, permitem que o impulso originado na região do nó sinusal atinja o nó AV e chegue aos ventrículos, após ter percorrido um "labirinto" criado pelas incisões. O procedimento foi complementado com comissurotomia mitral em seis pacientes, troca da valva mitral (TVM) em um paciente e TVM e plastia de DeVega (PdV) em valva tricúspide em um paciente. O primeiro paciente foi submetido a revisão cirúrgica para hemostasia. Nos demais, não houve problemas intra-operatórios. O segundo e o terceiro paciente apresentaram taquicardia atrial paroxística entre o terceiro e quinto dias de pós-operatório (PO). Um deles apresentou, também, no 15º dia. Em todos os casos, a arritmia foi controlada com amiodarona EV; o último paciente (com TVM e PdV) teve óbito no 45º dia de PO, por complicações infecciosas. Os pacientes restantes obtiveram alta hospitalar sem drogas antiarrítmicas. Em um período de um a dez meses (M = 5,4), os pacientes estão assintomáticos e o Holter mostra presença de ritmo atrial irregular permanente (com FC média de 70 a 80 bpm) com condução AV preservada; o ecodoppler mostra presença de contração atrial eficiente. Não houve recorrências de FA e nenhum dos pacientes. Em conclusão, podemos admitir que, a curto prazo, a técnica do "labirinto" na FA em reumáticos restaurou a contração atrial organizada e controlou a FC. Assim, pode contribuir para redução de fenômenos trombo-embólicos. Maior número de pacientes deve ser observado durante tempo prolongado para avaliação da eficácia do procedimento. The "maze" procedure for surgical treatment of chronic atrial fibrillation (AF) described by Cox was performed in 9 patients from July 91 to May 92; 7 were female and the ages range from 37 to 63y (51,4y). Eight patients had surgical rheumatic valve disfunction (mitral stenosis in 6; mitral double disfunction in 2 being 1 with associated tricuspid regurgitation) and 1 had recurrent paroxicistic AF with no valve disfunction. Surgical treatment was performed following the technique described by Cox and the surgery was completed with 6 mitral comissurotomies and 2 mitral valve replacements. Three patients had left atrial thrombosis. There were no immediate deaths and 1 patient died in the 45th day with infeccious complications. The first patient required reoperation for bleeding review. Second and 3rd patients presented transitory atrial tachycardia in 3rd and 5th day, controlled with intravenous amiodarone. No other complications were observed. In a mean follow up period of 5,4m (1 to 10 m), all patients were in regular atrial rhythm without antiarrhythmic drugs. Effective atrial contraction was demonstrated by ECHO in all patients and no one returned to AF. In conclusion, this initial follow up showed good results in rheumatic AF and more clinical observation is necessary to a definitive evaluation.

The study about the impact of atrioventricular node ablation and pacing therapy on clinical course in patients with permanent atrial fibrillation and unstable ventricular tachycardia induced by rapid ventricular response

The results of the study demonstrate that treatment with ACE inhibitors reduces the incidence of AF in patients with tachy-brady syndrome and DDDR pacing

Descripción del caso: Mujer de 79 años con antecedentes de hipertensión arterial, fibrilación auricular (FA) permanente anticoagulada (acenocumarol) e insuficiencia mitral. Barthel 90, Lowton-Brody: 2. Acude a urgencias por dolor costal (osteomuscular) de dos semanas de evolución, sin otros síntomas, siendo dada de alta y acudiendo nuevamente por epistaxis y disnea. Exploración y pruebas complementarias: destacar en la auscultación cardio-pulmonar: tonos arrítmicos con soplo sistólico en reborde esternal izquierdo, crepitantes hasta campos medios, con murmullo vesicular disminuido. Radiografía de tórax: masa hiliar derecha con engrosamiento pleural derecho, e infiltrado bilateral. Hemograma: hemoglobina 7.9 g/dl (previa 11.6 g/dl), leucocitos 11.57x10l. Bioquímica: PCR 72.90mg/l, urea 85 mg/l. Coagulación: INR indeterminado, actividad protrombina 4 aumenta el riesgo de sangrado. Se trata de un paciente pluripatológico, dependiente moderada, con mal cumplimiento tratamiento y de control de anticoagulación. Ante estos datos (anemización, ausencia de signos de infección o insuficiencia cardiaca), y los resultados de las pruebas, nos decantamos por la hemorragia alveolar como primera posibilidad diagnostica.

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in developed countries. It is a disease of the elderly and it is common in patients (pts) with organic heart disease. Hypertension, hart failure and valvular heart disease are predisposing factors to AF. To evaluate relationship of different types of AF with under lying heart diseases and demographic characteristics of pts as well. From June 2000 to December 2005, 1520 consecutive pts with AF were studied during echocardiographic check-up. According to the 2-D transthoracic echocardiography pts were divided into groups based on dominative underlying heart diseases. Electrocardiographically documented AF was subdivided into two groups: transient and chronic. Binary logistic regression was used to investigate relationship between gender, age, hypertension, diabetes and underlying heart diseases with the type of AF. The median age was 70 years, ranged between 16 and 99 years. Chronic AF was noted in 1095 (72.4%) pts. 772 (51%) were men. Diabetes mellitus was found in 205 (13.6%) pts, among them, 120 (58.5%) were females. Hypertensive heart disease (HHD) was the most common underlying heart disease in pts with AF (33.9%) followed by dilatative cardiomiophaty (DCM), 23.2%, coronary heart disease (CHD), 19.4% and valvular heart disease (VHD), 16.2%. DCM was the oldest group (71± ; ; 9 years) with highest frequency of male pts (64%). On the other hand, VHD was mostly presented in females (63%) with mean age being one of the bottommost (65± ; ; 11 years) and accompanied by the lowest prevalence of DM (3.7%) compared to the surveyed population. Pts with underlying CHD had highest prevalence of DM (23%). Lone AF was diagnosed in only 2.7% pts, mostly in younger males (men 73%, average age 56± ; ; 13 years) A significant frequency of transient AF was observed in females (OR=1.28, 95% CI=1.00-1.64), younger pts (OR=1.04, 95% CI=1.02-1.05), pts with lone AF (OR=3.85, 95% CI=1.64-9.04) and in pts with hypertension regardless the presence of other concomitant heart diseases (OR=1.47, 95% CI=1.07-2.04). Chronic AF was usual in men, older pts, pts with DCM (OR=2.19, 95% CI=1.20-4.01) and VHD (OR=4.27, 95% CI=2.24-8.15). The presence of diabetes was not significantly related to any of two types of AF. HHD was by far the most prevalent associated medical condition. Chronic AF was predominant in groups with advanced cardiac remodeling such as DCM and VHD.

Dengue fever is a viral infection transmitted by the mosquito, Aedes aegypti. Cardiac rhythm disorders, such as atrioventricular blocks and ventricular ectopic beats, appear during infection and are attributed to viral myocarditis. However, supraventricular arrhythmias have not been reported. We present a case of acute atrial fibrillation, with a rapid ventricular rate, successfully treated with intravenous amiodarone, in a 62-year-old man with dengue hemorrhagic fever, who had no structural heart disease.

The irregular ventricular rhythm that accompanies atrial fibrillation (AF) has been explained in terms of concealed conduction within the AV node (AVN). However, the cellular basis of concealed conduction in AF remains poorly understood. Our hypothesis is that electrotonic modulation of AVN propagation by atrial impulses blocked repetitively within the AVN is responsible for changes in function that lead to irregular ventricular rhythms in patients with AF. We have tested this idea using two different simplified computer ionic models of the AVN. The first ("black-box") model consisted of three cells: one representing the atrium, another one representing the AVN, and a third one representing the ventricle. The black-box model was used to establish the rules of behavior and predictions to be tested in a second, more elaborate model of the AVN. The latter ('nine-cell' model) incorporated a linear array of nine cells separated into three different regions. The first region of two cells represented the atrium; the second region of five cells represented the AV node; and the third region of two cells represented the ventricle. Cells were connected by appropriate coupling resistances. During regular atrial pacing, both models reproduced very closely the frequency dependence of AV conduction and refractoriness seen in patients and experimental animals. In addition, atrial impulses blocked within the AV node led to electrotonic inhibition or facilitation of propagation of immediately succeeding impulses. During simulated AF, using the nine-cell model, random variations in the atrial (A-A) interval yielded variations in the ventricular (V-V) interval but there was no scaling, i.e., the V-V intervals were not multiples of the A-A intervals. As such, the model simulated the statistical behavior of the ventricles in patients with AF, including: (1) the ventricular rhythm was random; and (2) the coefficient of variation (standard deviation/mean) of the ventricular rhythm was relatively constant at any given mean V-V interval. Analysis of cell responses revealed that repetitive atrial input at random A-A intervals resulted in complex patterns of concealment within the AVN cells. Consequently, the effects of electrotonic modulation were also random, which resuIted in a smearing of the AV conduction curve over A-A intervals that were larger than those predicted for 1:1 AV conduction. Hence, during AF, electrotonic modulation acts in concert with the frequency dependence of AVN conduction to result in complex patterns of ventricular activation. Finally, similarly to what was shown in patients, VVI pacing of the ventricle in the nine-cell model at the appropriate frequency led to blockade of nearly all anterograde (i.e., A-V) impulses. The essential feature here was that the retrograde impulse invading the AVN cells was followed by refractoriness with slow recovery of excitability, setting the stage for electrotonic inhibition of anterograde impulses. Overall, the results provide insight into the cellular mechanisms underlying AVN function and irregular ventricular response during AF.

The irregular ventricular rhythm that accompanies atrial fibrillation (AF) has been explained in terms of concealed conduction within the AV node (AVN). However, the cellular basis of concealed conduction in AF remains poorly understood. Our hypothesis is that electrotonic modulation of AVN propagation by atrial impulses blocked repetitively within the AVN is responsible for changes in function that lead to irregular ventricular rhythms in patients with AF. We have tested this idea using two different simplified computer ionic models of the AVN. The first ("black-box") model consisted of three cells: one representing the atrium, another one representing the AVN, and a third one representing the ventricle. The black-box model was used to establish the rules of behavior and predictions to be tested in a second, more elaborate model of the AVN. The latter ('nine-cell' model) incorporated a linear array of nine cells separated into three different regions. The first region of two cells represented the atrium; the second region of five cells represented the AV node; and the third region of two cells represented the ventricle. Cells were connected by appropriate coupling resistances. During regular atrial pacing, both models reproduced very closely the frequency dependence of AV conduction and refractoriness seen in patients and experimental animals. In addition, atrial impulses blocked within the AV node led to electrotonic inhibition or facilitation of propagation of immediately succeeding impulses. During simulated AF, using the nine-cell model, random variations in the atrial (A-A) interval yielded variations in the ventricular (V-V) interval but there was no scaling, i.e., the V-V intervals were not multiples of the A-A intervals. As such, the model simulated the statistical behavior of the ventricles in patients with AF, including: (1) the ventricular rhythm was random; and (2) the coefficient of variation (standard deviation/mean) of the ventricular rhythm was relatively constant at any given mean V-V interval. Analysis of cell responses revealed that repetitive atrial input at random A-A intervals resulted in complex patterns of concealment within the AVN cells. Consequently, the effects of electrotonic modulation were also random, which resuIted in a smearing of the AV conduction curve over A-A intervals that were larger than those predicted for 1:1 AV conduction. Hence, during AF, electrotonic modulation acts in concert with the frequency dependence of AVN conduction to result in complex patterns of ventricular activation. Finally, similarly to what was shown in patients, VVI pacing of the ventricle in the nine-cell model at the appropriate frequency led to blockade of nearly all anterograde (i.e., A-V) impulses. The essential feature here was that the retrograde impulse invading the AVN cells was followed by refractoriness with slow recovery of excitability, setting the stage for electrotonic inhibition of anterograde impulses. Overall, the results provide insight into the cellular mechanisms underlying AVN function and irregular ventricular response during AF.

Dengue fever is a viral infection transmitted by the mosquito, Aedes aegypti. Cardiac rhythm disorders, such as atrioventricular blocks and ventricular ectopic beats, appear during infection and are attributed to viral myocarditis. However, supraventricular arrhythmias have not been reported. We present a case of acute atrial fibrillation, with a rapid ventricular rate, successfully treated with intravenous amiodarone, in a 62-year-old man with dengue hemorrhagic fever, who had no structural heart disease.

Objective: The current study aims to investigate the role of echocardiographically measured epicardial adipose tissue (EAT) thickness in the prediction of new-onset atrial fibrillation (AF) following coronary artery bypass grafting (CABG) surgery. Methods: One hundred and twenty-four patients scheduled to undergo isolated on-pump CABG due to coronary artery disease were enrolled to the current study. Patient characteristics, medical history and perioperative variables were prospectively collected. EAT thickness was measured using transthoracic echocardiography (TTE). Any documented episode of new-onset postoperative AF (POAF) until discharge was defined as the study endpoint. Fortyfour participants with POAF served as AF group and 80 patients without AF served as Non-AF group. Results: Two groups were similar in terms of baseline echocardiographic and laboratory findings. In laboratory findings, the groups were similar in terms of the studied parameters, except N-terminal pro-brain natriuretic peptide (NT Pro-BNP), which was higher in AF group than in Non-AF group (P=0.035). The number of left internal mammary artery (LIMA) grafts was not different in both groups. AF group had higher cross-clamp (CC) and cardiopulmonary bypass (CPB) times than Non-AF group (P=0.01 and P

Introduction: Metabolic syndrome (MetS) is defined as an association between diabetes, hypertension, obesity and dyslipidemia and an increased risk of cardiovascular disease. Mitral annular calcification (MAC) is associated with several cardiovascular disorders, including coronary artery disease, atrial fibrillation (AF), heart failure, ischemic stroke and increased mortality. The CHA2DS2-VASc score is used to estimate thromboembolic risk in AF. However, the association among MAC, MetS and thromboembolic risk is unknown and was evaluated in the current study. Methods: The study group consisted of 94 patients with MAC and 86 patients with MetS. Patients were divided into two groups: those with and those without MAC. Results: Patients with MAC had a higher MetS rate (P