Temporal Trends and Temperature-Related Incidence of Electrical Storm: The TEMPEST Study (Temperature-Related Incidence of Electrical Storm).

BACKGROUND: The occurrence of ventricular tachyarrhythmias seems to follow circadian, daily, and seasonal distributions. Our aim is to identify potential temporal patterns of electrical storm (ES), in which a cluster of ventricular tachycardias or ventricular fibrillation, negatively affects short- and long-term survival. METHODS AND RESULTS: The TEMPEST study (Circannual Pattern and Temperature-Related Incidence of Electrical Storm) is a patient-level, pooled analysis of previously published data sets. Study selection criteria included diagnosis of ES, absence of acute coronary syndrome as the arrhythmic trigger, and ≥10 patients included. At the end of the selection and collection processes, 5 centers had the data set from their article pooled into the present registry. Temperature data and sunrise and sunset hours were retrieved from Weather Underground, the largest weather database available online. Total sample included 246 patients presenting with ES (221 men; age: 65±9 years). Each ES episode included a median of 7 ventricular tachycardia/ventricular fibrillation episodes. Fifty-nine percent of patients experienced ES during daytime hours (P<0.001). The prevalence of ES was significantly higher during workdays, with Saturdays and Sundays registering the lowest rates of ES (10.4% and 7.2%, respectively, versus 16.5% daily mean from Monday to Friday; P<0.001). ES occurrence was significantly associated with increased monthly temperature range when compared with the month before (P=0.003). CONCLUSIONS: ES incidence is not homogenous over time but seems to have a clustered pattern, with a higher incidence during daytime hours and working days. ES is associated with an increase in monthly temperature variation. CLINICAL TRIAL REGISTRATION: https://www.crd.york.ac.uk. Unique identifier: CRD42013003744.

La ablación de fibrilación auricular en España

Introducción: la ablación de la fibrilación auricular es uno de los procedimientos más frecuentemente realizados en las unidades de arritmias. La información de los resultados proviene de estudios prospectivos, registros multicéntricos y registros nacionales. Objetivo: evaluar la situación de la ablación de la fibrilación auricular en España a través de los datos recogidos en el Registro Español de Ablación, auspiciado por la Sección de Electrofisiología y Arritmias de la Sociedad Española de Cardiología. Métodos: los datos analizados provienen de los formularios remitidos, de forma voluntaria y anónima, por los diferentes centros hospitalarios, tanto de financiación pública como privada, durante el período 2008-2013. Cada centro fue analizado, año a año, de forma independiente. Analizamos los recursos humanos y materiales de los centros que realizaron procedimientos de ablación de fibrilación auricular durante ese período de tiempo. Asimismo, analizamos la técnica utilizada, el tipo de energía, complicaciones, etcétera. Comparamos todas las variables de forma evolutiva, año a año. Dividimos a los centros en función del número de procedimientos de ablación realizados cada año: 1-49, grupo A; 50-99, grupo B, y 100 o más, grupo C. Resultados: trescientos noventa y un centros (n=391) y 8.926 procedimientos de ablación fueron analizados. Año a año ha aumentado el número de centros que realizan ablación de fibrilación auricular y el número de procedimientos que realiza cada centro. El porcentaje de complicaciones se ha mantenido estable reduciéndose ligeramente la mortalidad. Los centros con mayor volumen tienen mayor dotación de recursos humanos y materiales. Realizan ablación de fibrilación auricular persistente con mayor frecuencia y realizan crioablación con menor frecuencia. Asimismo, estos centros tienen una menor incidencia de complicaciones. Conclusiones: la ablación de fibrilación auricular en España ha aumentado en los últimos años y presenta resultados similares a los recogidos en otros registros nacionales y multinacionales.

[Outcome of patients with local complications at the site of an implantable device]. / Evolución de los pacientes con complicaciones locales en la bolsa del generador de un dispositivo implantable.

OBJECTIVE: The recommendations for complete lead extraction because of local complications at the site of implantable devices have changed in the last 10 years. We analyze the outcome of patients who required an intervention because of a local complication between 2002 and 2010, in our Hospital. METHODS: We retrospectively studied 83 patients with a local complication that was classified according to skin integrity: 1. Integrity, and 2. Open skin. We analyzed the type of intervention: 1. Conservative approach, 2. Incomplete extraction, 3. Complete extraction. The endpoints were the needing a later intervention and a complete removal during follow up. RESULTS: The group of patients with complete system extraction showed a lower rate of re-intervention during an average follow up of 1000 days, when compared to other two groups (6.7% vs. 57.7 and 43.8%, P<.01). Incomplete extraction and conservative approach had a similar outcome, needing a complete extraction 25% and 37.5%, respectively. The skin integrity did not seem to be relevant for outcome in these two groups. An 8.4% incidence of endocarditis was observed; all of them had a previous history of incomplete extraction or conservative approach. CONCLUSIONS: Local complications treated with either a conservative approach or incomplete extraction are associated with a high rate of re-interventions, regardless of skin integrity, frequently needing final complete extraction and are associated to endocarditis.

Evolución de los pacientes con complicaciones locales en la bolsa del generador de un dispositivo implantable / Outcome of patients with local complications at the site of an implantable device

Objetivo: Las recomendaciones para la extracción completa de la bolsa de dispositivos implantables por problemas locales han cambiado. Analizamos la evolución entre 2002 y 2010 de los pacientes que requirieron una intervención por una complicación local en nuestro centro. Métodos: Ochenta y tres pacientes tuvieron un problema local de la bolsa que se clasificó según integridad de la piel: 1. Íntegra y 2. Abierta, y el tipo de intervención realizada: 1. Conservadora, 2. Extracción parcial y 3. Extracción completa. El objetivo primario fue la necesidad de reintervención posterior y la de extracción total durante el seguimiento. Resultados: El grupo de pacientes con extracción completa presentó una menor tasa de reintervención durante el seguimiento medio de 1,000 días comparado con los otros 2 grupos (6.7 vs. 57.7 y 43.8%, p < 0.01). La extracción parcial y la actitud conservadora mostraron una evolución parecida con una tasa de extracción completa final del 25% y del 37.5%. Se observó una incidencia de endocarditis del 8.4%; todos con antecedente de extracción parcial o actitud conservadora. Conclusiones: Las complicaciones de la bolsa, independientemente de la integridad de la piel, tratadas conservadoramente o con extracción parcial se asocian a alta tasa de reintervenciones, necesidad de extracción completa y evolución a endocarditis.

Objective: The recommendations for complete lead extraction because of local complications at the site of implantable devices have changed in the last 10 years. We analyze the outcome of patients who required an intervention because of a local complication between 2002 and 2010, in our Hospital. Methods: We retrospectively studied 83 patients with a local complication that was classified according to skin integrity: 1. Integrity, and 2. Open skin. We analyzed the type of intervention: 1. Conservative approach, 2. Incomplete extraction, 3. Complete extraction. The endpoints were the needing a later intervention and a complete removal during follow up. Results: The group of patients with complete system extraction showed a lower rate of reintervention during an average follow up of 1000 days, when compared to other two groups (6.7% vs. 57.7 and 43.8%, P<.01). Incomplete extraction and conservative approach had a similar outcome, needing a complete extraction 25% and 37.5%, respectively. The skin integrity did not seem to be relevant for outcome in these two groups. An 8.4% incidence of endocarditis was observed; all of them had a previous history of incomplete extraction or conservative approach. Conclusions: Local complications treated with either a conservative approach or incomplete extraction are associated with a high rate of re-interventions, regardless of skin integrity, frequently needing final complete extraction and are associated to endocarditis.

Value of early cardiovascular magnetic resonance for the prediction of adverse arrhythmic cardiac events after a first noncomplicated ST-segment-elevation myocardial infarction.

BACKGROUND: Infarct size (IS) determined by cardiac magnetic resonance (CMR) has proven an additional value, on top of left ventricular ejection fraction (LVEF), in prediction of adverse arrhythmic cardiac events (AACEs) in chronic ischemic heart disease. Its value soon after an acute ST-segment-elevation myocardial infarction remains unknown. Our aim was to determine whether early CMR can improve AACE risk prediction after acute ST-segment-elevation myocardial infarction. METHODS AND RESULTS: Patients admitted for a first noncomplicated ST-segment-elevation myocardial infarction were prospectively followed up. A total of 440 patients were included. All of them underwent CMR 1 week after admission. CMR-derived LVEF and IS (grams per meter squared) were quantified. AACEs included postdischarge sudden death, sustained ventricular tachycardia, and ventricular fibrillation either documented on ECG or recorded via an implantable cardioverter-defibrillator. Within a median follow-up of 2 years, 11 AACEs (2.5%) were detected: 5 sudden deaths (1.1%) and 6 spontaneous ventricular tachycardia/ventricular fibrillation. In the whole group, AACEs associated with more depressed LVEF (adjusted hazard ratio [95% confidence interval], 0.90 [0.83-0.97]; P<0.01) and larger IS (adjusted hazard ratio [95% confidence interval], 1.06 [1.01-1.12]; P=0.01). According to the corresponding area under the receiver operating characteristic curve, LVEF ≤36% and IS ≥23.5 g/m(2) best predicted AACEs. The vast majority of AACEs (10/11) occurred in patients with simultaneous depressed LVEF ≤36% and IS ≥23.5 g/m(2) (n=39). CONCLUSIONS: In the era of reperfusion therapies, occurrence of AACEs in patients with an in-hospital noncomplicated first ST-segment-elevation myocardial infarction is low. In this setting, assessment of an early CMR-derived IS could be useful for further optimization of AACE risk prediction.

Outcome of patients with syncope beyond the implantable loop recorder.

AIMS: The implantation of an implantable loop recorder (ILR) leads to the diagnosis in about 35% of patients with syncope of unknown origin. Information on outcome of patients in whom a diagnosis is not reached during the lifetime of the device is scarce. The aim of our study is to determine the outcome of these patients in terms of syncope recurrence and survival. METHODS AND RESULTS: An ILR was implanted to 97 patients with syncope of unknown origin. Patients were classified in groups A and B depending on their high or low risk, respectively, of having arrhythmic syncope. Diagnosis had not been reached in 60 patients (62%) when the ILR battery reached end operational life. Five patients were lost to follow up. During a median follow-up of 48 months after ILR explantation (interquartile range 36-56), 22 patients (40%) had recurrence of syncope (32% in group A vs. 48% in group B, P = 0.3). Syncopes with no neurally mediated profile were more frequent in group A (18 vs. 0%, P = 0.05) and neurally mediated profile syncopes were more frequent in group B (44 vs. 11%, P = 0.007). Five patients died, four of them in group A and 1 in group B (P = 0.4). No sudden or cardiac deaths were detected during follow-up. All deaths were due to non-cardiac causes. CONCLUSION: Recurrent syncope is common in patients in whom a diagnosis is not established after the full battery life of an ILR. The prognosis of these patients seems to be good, without observed sudden or cardiac death.

Ablation or conservative management of electrical storm due to monomorphic ventricular tachycardia: differences in outcome.

AIMS: Electrical storm (ES) is a life-threatening condition that predicts bad prognosis. Treatment includes antiarrhythmic drugs (AAD) and catheter ablation (CA). The present study aims to retrospectively compare prognosis in terms of survival and ES recurrence in 52 consecutive patients experiencing a first ES episode. METHODS AND RESULTS: Patients were admitted from 1995 to 2011 and treated for ES by conservative therapy (pharmacological, 29 patients) or by CA (23 patients), according to the physician's preference and time of occurrence, i.e. conservative treatments were more frequently administered during the first years of the study, as catheter ablation became more frequent as the years passed by. After a median follow-up of 28 months, no differences either in survival (32% vs. 29% P = 0.8) or in ES recurrence (38% in ablated vs. 57% in non-ablated patients, P = 0.29) were observed between groups. Low left ventricle ejection fraction (LVEF) was the only variable associated with ES recurrence in ablated patients. When including patients with LVEF > 25%, ES recurrence was significantly lower in ablated patients (24 months estimated risk of ES recurrence was 21% vs. 62% in ablated and non-ablated patients, respectively); however, no benefit in survival was observed. CONCLUSION: Our data suggest that in most patients, especially those with an LVEF > 25%, catheter ablation following a first ES episode, decreases the risk of ES recurrence, without increasing survival.

Síncope y bloqueo de rama. Rendimiento del uso escalonado del estudio electrofisiológico y de la monitorización electrocardiográfica prolongada / Syncope and bundle branch block. Diagnostic yield of a stepped use of electrophysiology study and implantable loop recorders

Introducción y objetivos. El objetivo del estudio es evaluar la utilidad de un protocolo diagnóstico escalonado mediante estudio electrofisiológico (EEF) y registrador de eventos implantable (REI) en pacientes con síncope y bloqueo de rama (BR). Métodos. Se realizó un EEF con provocación farmacológica con procainamida en 85 pacientes consecutivos remitidos por síncope y BR tras una evaluación inicial no diagnóstica. En aquellos sin indicación de desfibrilador implantable, se implantó un REI. Se realizó seguimiento hasta el diagnóstico o el agotamiento de la batería del dispositivo. Resultados. El EEF fue diagnóstico en 36 pacientes (42%); el mecanismo más frecuente fue el bloqueo auriculoventricular (BAV) paroxístico (n=27), seguido por la taquicardia ventricular (TV) (n=6). Todos los pacientes con TV tuvieron cardiopatía estructural y mayor prevalencia de BR izquierda. Se implantó un REI a 38 pacientes, y se alcanzó un diagnóstico en 13 (34%); el BAV paroxístico fue el más frecuente (n=10). La mediana de seguimiento hasta el diagnóstico de BAV paroxístico mediante el REI fue 97 días (intervalo intercuartilo, 60-117 días). El BAV paroxístico fue más frecuente en los pacientes con BR derecha y PR prolongado y/o desviación del eje. No se observaron TV o muertes arrítmicas durante el seguimiento. Conclusiones. En pacientes con síncope y BR, la etiología principal está representada por el BAV paroxístico, seguido por la TV. El uso escalonado del EEF y del REI en los casos negativos permite alcanzar un rendimiento diagnóstico alto y con seguridad, dado que la TV suele identificarse durante el EEF(AU)

Introduction and objectives: The objective of this study was to determine the diagnostic yield of a stepped protocol involving an electrophysiologic study (EPS) and implantable loop recorders (ILR) in patients with syncope and bundle branch block (BBB). Methods: Eighty-five consecutive patients referred for syncope and BBB after initial non-diagnostic assessment underwent EPS including a pharmacological challenge with procainamide. Those patients without indication for defibrillator implantation received ILRs. Follow-up continued until diagnosis or end of battery life. Results: The EPS was diagnostic in 36 patients (42%). The most frequent diagnoses were paroxysmal atrioventricular block (AVB) (n = 27), followed by ventricular tachycardia (VT) (n = 6). All patients with VT had structural heart disease; left BBB was more prevalent in this group. Thirty-eight patients received ILRs and diagnosis was achieved in 13 (34%) of them; paroxysmal AVB (n = 10) was the most frequent diagnosis. Median follow-up to diagnosis of paroxysmal AVB was 97 days (interquartile range 60-117 days). Paroxysmal AVB was more frequent in patients with right BBB and prolonged PR interval and/or axis deviation. We found no occurrence of VT or arrhythmic death during follow-up. Conclusions: The most common etiology of syncope in patients with BBB was paroxysmal AVB, followed by VT. The stepped use of EPS and ILR in negative patients enables us to safely achieve a high diagnostic yield, given that VT is usually diagnosed during EPS(AU)

Syncope and bundle branch block. Diagnostic yield of a stepped use of electrophysiology study and implantable loop recorders.

INTRODUCTION AND OBJECTIVES: The objective of this study was to determine the diagnostic yield of a stepped protocol involving an electrophysiologic study (EPS) and implantable loop recorders (ILR) in patients with syncope and bundle branch block (BBB). METHODS: Eighty-five consecutive patients referred for syncope and BBB after initial non-diagnostic assessment underwent EPS including a pharmacological challenge with procainamide. Those patients without indication for defibrillator implantation received ILRs. Follow-up continued until diagnosis or end of battery life. RESULTS: The EPS was diagnostic in 36 patients (42%). The most frequent diagnoses were paroxysmal atrioventricular block (AVB) (n=27), followed by ventricular tachycardia (VT) (n=6). All patients with VT had structural heart disease; left BBB was more prevalent in this group. Thirty-eight patients received ILRs and diagnosis was achieved in 13 (34%) of them; paroxysmal AVB (n=10) was the most frequent diagnosis. Median follow-up to diagnosis of paroxysmal AVB was 97 days (interquartile range 60-117 days). Paroxysmal AVB was more frequent in patients with right BBB and prolonged PR interval and/or axis deviation. We found no occurrence of VT or arrhythmic death during follow-up. CONCLUSIONS: The most common etiology of syncope in patients with BBB was paroxysmal AVB, followed by VT. The stepped use of EPS and ILR in negative patients enables us to safely achieve a high diagnostic yield, given that VT is usually diagnosed during EPS.

Implantation of single-lead atrioventricular permanent pacemakers guided by electroanatomic navigation without the use of fluoroscopy.

AIMS: Fluoroscopy is the standard and almost unique tool used for cardiac imaging during permanent pacemaker implantation, and its use implies exposure of patients and operators to radiation. The usefulness for this purpose of electroanatomic systems not based on fluoroscopy is unknown. Our aim was to study the feasibility of implanting single-lead VDD pacemakers without the use of fluoroscopy. METHODS AND RESULTS: EnSite NavX, a catheter navigation tool based on the creation of a voltage gradient across the thorax of the patient, was used as an exclusive imaging tool during the implantation of single-lead atrioventricular (VDD) permanent pacemakers in 15 consecutive patients with atrioventricular block and normal sinus node function. A retrospective series of 15 consecutive patients in whom VDD pacemakers were implanted under fluoroscopic guidance was used as a control group. The pacemaker could be implanted in all patients. Time spent to obtain the right ventricle anatomy was 10.1 +/- 5.4 min and time to place the lead in an adequate position was 10.1 +/- 7.8 min. Total implant time was 59.3 +/- 15.6 min (51.5 +/- 12.3 min in the control group; P = 0.14). In one patient, a short pulse of radioscopy was needed for a correct catheterization of the subclavian vein. No complications were observed during the procedure. One lead dislodgement that required re-operation was detected 24 h after implantation. At 3 months follow-up, all pacemakers were functioning properly, with adequate pacing and sensing thresholds. CONCLUSION: Electroanatomic navigation systems such as NavX can be used for cardiac imaging during single-lead atrioventricular pacemaker implantation as a reliable and safe alternative to fluoroscopy.

[Changes in the spectral characteristics of ventricular fibrillation in lesions produced by radiofrequency ablation. An experimental study]. / Modificaciones de las características espectrales de la fibrilación ventricular en las lesiones producidas con radiofrecuencia. Estudio experimental.

INTRODUCTION AND OBJECTIVES: Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. METHODS: Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compared. RESULTS: In the ablated zones, significant reductions were observed in the spectral density of the dominant (0.168+/-0.113 mV(2)/Hz vs 0.025+/-0.018 mV(2)/Hz; P< .001) and mean frequencies (0.053+/-0.057 mV(2)/Hz vs 0.012+/-0.016 mV(2)/Hz; P< .001), the normalized energy around the dominant frequency (0.860+/-0.570 vs 0.128+/-0.091; P< .001), and the standard deviation of the power spectrum (0.031+/-0.020 mV(2)/Hz vs 0.004+/-0.001 mV(2)/Hz; P< .001). There was no significant change in the dominant (16.2+/-5.6 vs 14.8+/-1.8 Hz) or mean frequency (17.7+/-3.4 vs 16.6+/-1.3 Hz). The spectral parameters that could be used in a multivariate model to identify the lesion were the standard deviation of the power spectrum and the spectral density of the mean frequency. CONCLUSIONS: During ventricular fibrillation, the spectral parameters associated with spectral power and spectral energy were significantly altered in zones with radiofrequency lesions and could be used to identify those zones. There was no significant change in either the dominant or mean frequency in these zones.

Modificaciones de las características espectrales de la fibrilación ventricular en las lesiones producidas con radiofrecuencia. Estudio experimental / Changes in the spectral characteristics of ventricular fibrillation in lesions produced by radiofrequency ablation. An experimental study

Introducción y objetivos. Aunque se dispone de información sobre las modificaciones en el dominio del tiempo de los registros electrofisiológicos en zonas lesionadas con radiofrecuencia, los datos disponibles en el dominio de la frecuencia son muy escasos. Se analizan las modificaciones de las características espectrales de la fibrilación ventricular en zonas lesionadas con radiofrecuencia. Métodos. En 11 preparaciones de corazón aislado y perfundido de conejo, se registra la fibrilación ventricular con un electrodo múltiple epicárdico situado en la pared libre ventricular izquierda. Se comparan los parámetros espectrales obtenidos mediante análisis de Fourier antes y después de practicar lesiones transmurales con radiofrecuencia. Resultados. En las zonas lesionadas disminuye significativamente la densidad espectral de las frecuencias dominante (0,168 ± 0,113 y 0,025 ± 0,018 mV2/Hz; p < 0,001) y media (0,053 ± 0,057 y 0,012 ± 0,016 mV2/Hz; p < 0,001), la energía normalizada alrededor de la frecuencia dominante (0,860 ± 0,570 y 0,128 ± 0,091; p < 0,001) y la desviación típica del espectro de potencias (0,031 ± 0,020 y 0,004 ± 0,001 mV2/Hz; p < 0,001). No se modifican significativamente las frecuencias dominante (16,2 ± 5,6 y 14,8 ± 1,8 Hz) y media (17,7 ± 3,4 y 16,6 ± 1,3 Hz). Los parámetros espectrales aceptados en el modelo multivariable para indicar que los registros se efectúan en la lesión son la desviación típica del espectro de potencias y la densidad espectral de la frecuencia media. Conclusiones. Durante la fibrilación ventricular, los parámetros relacionados con la potencia y la energía espectral muestran modificaciones significativas en las zonas lesionadas con radiofrecuencia y pueden ayudar a identificarlas. Las frecuencias dominante y media no se modifican significativamente en las zonas lesionadas

Introduction and objectives. Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. Methods. Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compared. Results. In the ablated zones, significant reductions were observed in the spectral density of the dominant (0.168±0.113 mV2/Hz vs 0.025±0.018 mV2/Hz; P<.001) and mean frequencies (0.053±0.057 mV2/Hz vs 0.012±0.016 mV2/Hz; P<.001), the normalized energy around the dominant frequency (0.860±0.570 vs 0.128±0.091; P<.001), and the standard deviation of the power spectrum (0.031±0.020 mV2/Hz vs 0.004±0.001 mV2/Hz; P<.001). There was no significant change in the dominant (16.2±5.6 vs 14.8±1.8 Hz) or mean frequency (17.7±3.4 vs 16.6±1.3 Hz). The spectral parameters that could be used in a multivariate model to identify the lesion were the standard deviation of the power spectrum and the spectral density of the mean frequency. Conclusions. During ventricular fibrillation, the spectral parameters associated with spectral power and spectral energy were significantly altered in zones with radiofrequency lesions and could be used to identify those zones. There was no significant change in either the dominant or mean frequency in these zones

[Influence of recording mode (unipolar or bipolar) on the spectral characteristics of epicardial recordings in ventricular fibrillation. An experimental study]. / Influencia del tipo de registro (unipolar o bipolar) en las características espectrales de los registros epicárdicos de la fibrilación ventricular. Estudio experimental.

INTRODUCTION AND OBJECTIVES: The aim of this study was to examine the hypothesis that the recording mode (i.e., unipolar or bipolar) affects the information obtained using spectral analysis techniques during ventricular fibrillation by carrying out an experiment using epicardial electrodes. METHODS: Recordings of ventricular fibrillation were obtained in 29 isolated rabbit hearts using a multiple-electrode probe located on the left ventricular free wall. The parameter values obtained in the frequency domain (by Fourier analysis) using unipolar or bipolar electrodes, different interelectrode distances, and different orientations (i.e., horizontal, vertical or diagonal) were compared. RESULTS: Changing the recording mode (i.e., unipolar to bipolar) or the interelectrode distance significantly altered the mean frequency (P< .0001) and the normalized energy of the spectrum (+/-1 Hz) around the dominant frequency (P< .05), though the changes were small relative to the dominant frequency. Cross-spectral analysis showed that the coherence between unipolar recordings decreased as the interelectrode distance increased, while the opposite occurred with the coherence between unipolar and bipolar recordings. The two coherences were inversely correlated such that the greater the former coherence, the less the coherence between unipolar and bipolar recordings (r=0.29; P< .0001; n=348). CONCLUSIONS: The recording mode (i.e., unipolar or bipolar) used influenced the information obtained using spectral analysis techniques from epicardial recordings of ventricular fibrillation. Differences were observed in the mean frequency and in the frequency distribution, but they were very small relative to the dominant frequency.

Influencia del tipo de registro (unipolar o bipolar) en las características espectrales de los registros epicárdicos de la fibrilación ventricular. Estudio experimental / Influence of recording mode (unipolar or bipolar) on the spectral characteristics of epicardial recordings in ventricular fibrillation. An experimental study

Introducción y objetivos. Se evalúa la hipótesis de que el tipo de registro (unipolar o bipolar) influye en la información obtenida mediante técnicas espectrales durante la fibrilación ventricular en un modelo experimental que utiliza electrodos epicárdicos. Métodos. En 29 corazones aislados de conejo se obtienen registros de la fibrilación ventricular con un electrodo múltiple situado en la pared libre del ventrículo izquierdo. Se comparan los parámetros obtenidos en el dominio de la frecuencia (análisis de Fourier) al utilizar electrodos unipolares o bipolares con varias separaciones entre los electrodos en distintas direcciones (horizontal, vertical o diagonales). Resultados. La modalidad de registro (unipolar o bipolar) y la separación entre los electrodos han introducido diferencias significativas en la frecuencia media (p < 0,0001) y en la energía normalizada del espectro alrededor de la frecuencia dominante (± 1 Hz) (p < 0,05), pero éstas han sido mínimas al considerar la frecuencia dominante. En el análisis espectral cruzado, se ha observado que la coherencia entre los registros unipolares disminuye al aumentar la separación entre los electrodos, mientras que ocurre lo contrario al analizar la coherencia entre los unipolares y los bipolares. Ambas coherencias se correlacionan inversamente, de tal modo que cuanto mayor es la primera menor es la de los unipolares respecto a los bipolares (r = 0,29; p < 0,0001; n = 348). Conclusiones. El tipo de registro utilizado (unipolar o bipolar) introduce variaciones en la información obtenida mediante técnicas espectrales en los registros epicárdicos de la fibrilación ventricular. Estas diferencias se observan en la frecuencia media y en la distribución de frecuencias del espectro, pero son muy pequeñas al considerar la frecuencia dominante (AU)

Introduction and objectives. The aim of this study was to examine the hypothesis that the recording mode (i.e., unipolar or bipolar) affects the information obtained using spectral analysis techniques during ventricular fibrillation by carrying out an experiment using epicardial electrodes. Methods. Recordings of ventricular fibrillation were obtained in 29 isolated rabbit hearts using a multiple-electrode probe located on the left ventricular free wall. The parameter values obtained in the frequency domain (by Fourier analysis) using unipolar or bipolar electrodes, different interelectrode distances, and different orientations (i.e., horizontal, vertical or diagonal) were compared. Results. Changing the recording mode (i.e., unipolar to bipolar) or the interelectrode distance significantly altered the mean frequency (P<.0001) and the normalized energy of the spectrum (±1 Hz) around the dominant frequency (P<.05), though the changes were small relative to the dominant frequency. Cross-spectral analysis showed that the coherence between unipolar recordings decreased as the interelectrode distance increased, while the opposite occurred with the coherence between unipolar and bipolar recordings. The two coherences were inversely correlated such that the greater the former coherence, the less the coherence between unipolar and bipolar recordings (r=0.29; P<.0001; n=348). Conclusions. The recording mode (i.e., unipolar or bipolar) used influenced the information obtained using spectral analysis techniques from epicardial recordings of ventricular fibrillation. Differences were observed in the mean frequency and in the frequency distribution, but they were very small relative to the dominant frequency (AU)

Implantación de un sistema de resincronización cardiaca en un paciente con vena cava superior izquierda persistente / Implantation of a cardiac resynchronization system in a patient with a persistent left superior vena cava

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Selective myocardial isolation and ventricular fibrillation.

BACKGROUND: Few experimental studies have analyzed the effects of selective radiofrequency (RF) lesions upon ventricular fibrillation (VF). The RF-induced isolation of selected zones would make it possible to determine whether these zones are essential for existence of the arrhythmia. METHODS: In 31 Langendorff-perfused rabbit hearts, the characteristics and inducibility of VF were analyzed before and after the induction of RF lesions comprising: (1) the posterior zone of the septum and of the walls of both ventricles (n = 10); (2) the anterior zone of the septum and of the walls of both ventricles (n = 11); and (3) the midseptal zone (n = 10). RESULTS: Complete isolation of the zone encompassed by the lesions was obtained in 5, 6, and 5 experiments of series 1, 2, and 3, respectively. In these experiments, the arrhythmia was only induced from within the zone encompassed by the lesions in one experiment belonging to series 2 (P < 0.05 with respect to baseline). In contrast, in all but one of the cases in series 2, VF could be induced from outside the isolated zone (ns vs baseline). Partial isolation was obtained in five experiments of each series. In these experiments, on pacing from within the partially isolated zone, sustained VF was not induced in any experiment (P < 0.05 with respect to baseline), while in all cases VF could be induced on pacing from the external zone (ns vs baseline). CONCLUSION: In the experimental model used, the three zones studied were not essential for maintaining VF. In most cases, their partial or total isolation avoided inducibility of the arrhythmia in those zones, though not in the remaining myocardium.

[Effect of flecainide on longitudinal and transverse conduction velocities in ventricular myocardium. An experimental study]. / Efectos de la flecainida sobre las velocidades de conducción longitudinal y transversal en el miocardio ventricular. Estudio experimental.

It is known that the effect of flecainide on longitudinal and transverse ventricular conduction velocities depends on the coupling interval. If this is so, whether the longitudinal or transverse direction is predominantly affected could depend on the magnitude of the coupling interval. In order to investigate this hypothesis, we studied the effect of flecainide, 1 micromol/L, on conduction velocities in excised heart preparations from 11 rabbits using a basal cycle length of 250 ms and inserting two extrastimuli at a decreasing coupling interval. Flecainide significantly reduced both conduction velocities. However, the effect increased as the coupling interval decreased for only the longitudinal velocity. At long coupling intervals, flecainide produced a greater reduction in transverse than longitudinal velocity, whereas, at short intervals, both velocities were affected similarly.

Efectos de la flecainida sobre las velocidades de conducción longitudinal y transversal en el miocardio ventricular. Estudio experimental / Effect of flecainide on longitudinal and transverse conduction velocities in ventricular myocardium. An experimental study

Es conocido que el efecto de la flecainida sobre las velocidades de conducción ventricular longitudinal y transversal depende del acoplamiento entre estímulos. Si esto es así, el predominio de los efectos en sentido longitudinal frente al transversal puede variar en función de dicho acoplamiento. Con el objetivo de analizar dicha hipótesis, se ha estudiado el efecto de la flecainida (1 µmol/l) sobre dichas velocidades de conducción en 11 preparaciones de corazón aislado de conejo, para lo que se ha utilizado un tren base de estimulación de 250 ms y se han acoplado 2 extraestímulos con acoplamiento decreciente. La flecainida ha reducido ambas velocidades de forma significativa. Este efecto se ha incrementado al reducir el acoplamiento únicamente en el caso de la velocidad longitudinal. Con acoplamientos largos, la flecainida ha producido una mayor reducción de la velocidad transversal que de la longitudinal, mientras que para intervalos cortos ha afectado en la misma proporción a ambas velocidades

It is known that the effect of flecainide on longitudinal and transverse ventricular conduction velocities depends on the coupling interval. If this is so, whether the longitudinal or transverse direction is predominantly affected could depend on the magnitude of the coupling interval. In order to investigate this hypothesis, we studied the effect of flecainide, 1 µmol/L, on conduction velocities in excised heart preparations from 11 rabbits using a basal cycle length of 250 ms and inserting two extrastimuli at a decreasing coupling interval. Flecainide significantly reduced both conduction velocities. However, the effect increased as the coupling interval decreased for only the longitudinal velocity. At long coupling intervals, flecainide produced a greater reduction in transverse than longitudinal velocity, whereas, at short intervals, both velocities were affected similarly

Syncopal monomorphic ventricular tachycardia with pleomorphism, sensitive to antitachycardia pacing in a patient with Brugada syndrome.

Polymorphic ventricular tachycardia and ventricular fibrillation are the most common arrhythmias in Brugada syndrome, causing syncope or sudden death. Sustained monomorphic ventricular tachycardias are rare in this context. We report the case of a 41-year-old man with repetitive syncopal episodes and an ajmaline-induced characteristic Brugada ECG pattern, in whom episodes of monomorphic ventricular tachycardia with pleomorphism and response to ventricular pacing were documented.