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To repair congenital heart defects by means of open heart surgery, the surgeon needs guidance about the location and distribution of the specialized conduction tissues, in order to avoid their direct damage and consequent conduction disturbances. This review addresses the historical steps of the morphological study of the conduction system in different types of heart defects, providing updated information about the subject.

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The past few years have given rise to extensive research on atrial conduction disorders and their clinical relevance. Most notably, an association between interatrial block and supraventricular arrhythmias has been discovered. This disorder, recently termed 'Bayés' syndrome', has important clinical implications. In this article, the authors review normal atrial conduction and associated disorders. A particular focus is placed on Bayés' syndrome and the relationship between interatrial block and supraventricular arrhythmias in different clinical scenarios. The report also outlines the current progress in the study of this syndrome and highlights areas requiring further investigation.

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Interatrial blocks (IABs) are well described and accepted in the scientific community. In the last four decades major discoveries were made including its physiopathology, ECG presentation, classification and association with atrial tachyarrhythmias (advanced IAB). This article will briefly review the state of the art on the understanding of advanced IAB as an electrical substrate for atrial tachyarrhythmias as well as the future directions.

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A 44-year-old man with aortic valve insufficiency and stenosis underwent aortic valve replacement depicting interesting ECG changes. This unique case is discussed, contributing to the understanding of a trifascicular left intraventricular conduction system.

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En este artículo hemos querido establecer que el bloqueo interauricular existe como entidad anatomoeléctrica y que debe ser considerado como un verdadero bloqueo. El bloqueo interauricular presenta diferentes grados al igual que otros bloqueos del sistema de conducción. Puede presentarse como expresión de remodelado puramente eléctrico o acompañar alteraciones estructurales que dilaten las aurículas. Se encuentra asociado a arritmias supraventriculares y es probablemente un predictor de accidente cerebrovascular cardioembólico. El bloqueo interauricular puede presentarse de manera transitoria, y en ciertas circunstancias clínicas, puede ser reversible. El aporte del mapeo endocavitario ha incrementado el conocimiento sobre su anatomía y fisiopatología, y posiblemente la magnetocardiografía podría contribuir al estudio no invasivo de esta entidad. La terminología a utilizar debería ser bloqueo interauricular de primer, segundo y tercer grado o alternativamente, y en función de simplificar: parcial o avanzado. La morfología de la onda P, en función de diagnosticar el grado avanzado, siempre debería ser tenida en cuenta. Para finalizar, debemos reconocer el aporte fundamental que el Dr. Bayés de Luna ha establecido sobre la relación del bloqueo interauricular con las arritmias supraventriculares conformando un síndrome arrítmico indiscutido; lo cual a nuestro criterio representa un aporte mayor al conocimiento de la electrocardiografía y la electrofisiología, y hace meritorio que este síndrome arrítmico sea denominado <

In this article we aimed to establish that interatrial block exists as an anatomical-electrical entity, which should be considered a true block. Interatrial block presents with different degrees as other blocks in the conduction system. It shows a correlation with the left atrium size, however, it can be seen in patients with normal atrial size too. Interatrial block is strongly associated with atrial arrhythmias and it could be considered a predictor of cardioembolic stroke. Interatrial block is an expression of atrial electrical remodeling and dysfunction. IAB can be transient and in certain clinical circumstances, may be reversible. The contribution of endocardial mapping has increased our knowledge of the anatomy and pathophysiology of interatrial block. Magnetocardiography could be a possible non-invasive procedure to further investigate this entity. The interatrial block classification should include first, second and third degree or alternatively, in order to simplify the terminology: partial or advanced. The P wave morphology should always be taking into consideration when diagnosing this condition. Finally, without the initial description of interatrial block made by Dr. Bayés de Luna, it would be impossible to understand interatrial block as an anatomical and electrical substrate for atrial arrhythmias. It is our opinion that this represents a major contribution to the knowledge of electrocardiography and electrophysiology, and makes commendable that this arrhythmic syndrome should be called <

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In this article we aimed to establish that interatrial block exists as an anatomical-electrical entity, which should be considered a true block. Interatrial block presents with different degrees as other blocks in the conduction system. It shows a correlation with the left atrium size, however, it can be seen in patients with normal atrial size too. Interatrial block is strongly associated with atrial arrhythmias and it could be considered a predictor of cardioembolic stroke. Interatrial block is an expression of atrial electrical remodeling and dysfunction. IAB can be transient and in certain clinical circumstances, may be reversible. The contribution of endocardial mapping has increased our knowledge of the anatomy and pathophysiology of interatrial block. Magnetocardiography could be a possible non-invasive procedure to further investigate this entity. The interatrial block classification should include first, second and third degree or alternatively, in order to simplify the terminology: partial or advanced. The P wave morphology should always be taking into consideration when diagnosing this condition. Finally, without the initial description of interatrial block made by Dr. Bayés de Luna, it would be impossible to understand interatrial block as an anatomical and electrical substrate for atrial arrhythmias. It is our opinion that this represents a major contribution to the knowledge of electrocardiography and electrophysiology, and makes commendable that this arrhythmic syndrome should be called «Bayés' syndrome¼

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BACKGROUND: Sarcoidosis is a multisystem granulomatous disease of unknown origin that can cause sudden death. OBJECTIVE: Electrophysiological evaluation of patients with suspected sarcoidosis with cardiac involvement. METHODS: We studied 22 patients with mean age of 55.32 ± 13.13 years, diagnosed with sarcoidosis and suspected cardiac involvement. These patients underwent clinical evaluation, laboratory tests, electrocardiogram, echocardiogram, 24-hour Holter, technetium or gallium scintigraphy and electrophysiological study. In selected cases, we performed positron emission tomography or magnetic resonance imaging. Patients were followed up in the outpatient care service with quarterly visits. RESULTS: Cardiac involvement was confirmed in four (18.2%) patients. Ventricular extrasystoles with density > 100/24 h were documented in 24-Holter monitoring in 12 (54.5%) patients. Electrophysiological studies revealed an increased HV interval in seven patients (31.8%) and increased Wenckebach point in four (18.2%) patients. There was induction of atrial fibrillation in seven patients (31.8%) and sustained ventricular tachycardia in one patient (4.5%). Four patients with confirmed cardiac sarcoidosis had documented ventricular extrasystoles with density > 100/24 h. Out of these, two had prolonged HV interval and atrial fibrillation was induced in two of them. Sustained ventricular tachycardia was not induced in any of these patients. After mean follow-up period of 20.9 ± 15.7 months, one patient with cardiac sarcoidosis had sudden death. CONCLUSION: Patients with sarcoidosis and suspected cardiac involvement have a high prevalence of ventricular extrasystoles (VEs) and conduction system disorders.

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FUNDAMENTO: Sarcoidose é uma doença granulomatosa multissistêmica de origem desconhecida que pode causar morte súbita. OBJETIVO: Avaliação eletrofisiológica de pacientes com sarcoidose com suspeita de comprometimento cardíaco. MÉTODOS: Foram estudados 22 pacientes com média de idade de 55,32 ±13,13 anos, com diagnóstico de sarcoidose e suspeita de comprometimento cardíaco. Foram submetidos à avaliação clínica, exames laboratoriais, eletrocardiograma, ecocardiograma, Holter de 24h, cintilografia com gálio ou tecnécio e estudo eletrofisiológico. Em casos selecionados foi realizada tomografia por emissão de pósitrons ou ressonância magnética. Os pacientes foram seguidos ambulatoriamente com consultas trimestrais. RESULTADOS: Comprometimento cardíaco foi comprovado em quatro (18,2 por cento) pacientes. Extrassístoles ventriculares com densidade > 100/24h foram documentadas no Holter de 24h em 12 (54,5 por cento) pacientes. O estudo eletrofisiológico revelou aumento do intervalo HV em sete (31,8 por cento) e ponto de Wenckebach aumentado em quatro (18,2 por cento) pacientes. Houve indução de fibrilação atrial em sete (31,8 por cento) e de taquicardia ventricular sustentada em um (4,5 por cento). Nos quatro pacientes com sarcoidose cardíaca confirmada, extrassístoles ventriculares, com densidade > 100/24h foram documentadas em todos, dois apresentavam intervalo HV prolongado e fibrilação atrial foi induzida em dois. Taquicardia ventricular sustentada não foi induzida em nenhum desses pacientes. Após período médio de acompanhamento de 20,9 ± 15,7 meses, um paciente com sarcoidose cardíaca apresentou morte súbita. CONCLUSÃO: Pacientes com sarcoidose e suspeita de envolvimento cardíaco apresentam alta prevalência de EVs e distúrbios do sistema de condução.

BACKGROUND: Sarcoidosis is a multisystem granulomatous disease of unknown origin that can cause sudden death. OBJECTIVE: Electrophysiological evaluation of patients with suspected sarcoidosis with cardiac involvement. METHODS: We studied 22 patients with mean age of 55.32 ± 13.13 years, diagnosed with sarcoidosis and suspected cardiac involvement. These patients underwent clinical evaluation, laboratory tests, electrocardiogram, echocardiogram, 24-hour Holter, technetium or gallium scintigraphy and electrophysiological study. In selected cases, we performed positron emission tomography or magnetic resonance imaging. Patients were followed up in the outpatient care service with quarterly visits. RESULTS: Cardiac involvement was confirmed in four (18.2 percent) patients. Ventricular extrasystoles with density > 100/24h were documented in 24-Holter monitoring in 12 (54.5 percent) patients. Electrophysiological studies revealed an increased HV interval in seven patients (31.8 percent) and increased Wenckebach point in four (18.2 percent) patients. There was induction of atrial fibrillation in seven patients (31.8 percent) and sustained ventricular tachycardia in one patient (4.5 percent). Four patients with confirmed cardiac sarcoidosis had documented ventricular extrasystoles with density > 100/24h. Out of these, two had prolonged HV interval and atrial fibrillation was induced in two of them. Sustained ventricular tachycardia was not induced in any of these patients. After mean follow-up period of 20.9 ± 15.7 months, one patient with cardiac sarcoidosis had sudden death. CONCLUSION: Patients with sarcoidosis and suspected cardiac involvement have a high prevalence of ventricular extrasystoles (VEs) and conduction system disorders.

FUNDAMENTOS: Sarcoidosis es una enfermedad granulomatosa multisistémica de origen desconocido que puede causar la muerte súbita. OBJETIVOS:Evaluación electrofisiológica de los pacientes con sarcoidosis con sospecha de afectación cardíaca. MÉTODOS:Se estudiaron a 22 pacientes con una media de edad de 55,32 ± 13,13 años, con diagnóstico de sarcoidosis y sospecha de afectación cardíaca.Se sometieron a evaluación clínica, exámenes de laboratorio, electrocardiograma, ecocardiograma, Holter de 24 h, centellografía con galio o tecnecio y estudio electrofisiológico. En los casos seleccionados se realizó tomografía por emisión de positrones o la resonancia magnética.Los pacientes fueron seguidos en ambulatorio, en consultas trimestrales. RESULTADOS:La afectación cardíaca se comprobó en cuatro (18,2 por ciento) pacientes.Extrasístoles ventriculares con densidad > 100/24 h se documentaron en el Holter de 24 h en 12 (54,5 por ciento) pacientes.Los estudios electrofisiológicos revelaron un aumento del intervalo HV en siete (31,8 por ciento) y punto de Wenckebach aumentado en cuatro (18,2 por ciento) pacientes. No hubo inducción de fibrilación auricular en siete (31,8 por ciento) y de taquicardia ventricular sostenida en uno (4,5 por ciento). En los cuatro pacientes con sarcoidosis cardiaca confirmada, extrasístoles ventriculares (EVs), con densidad > 100/24 h se documentaron en todos, dos presentaban prolongación del intervalo HV y fibrilación auricular se indujo en dos. La taquicardia ventricular sostenida no fue inducida en cualquiera de estos pacientes. Después de un periodo medio de seguimiento de 20,9 ± 15,7 meses, un paciente con sarcoidosis cardíaca tuvo muerte súbita. CONCLUSIÓN: Los pacientes con sarcoidosis y sospecha de afectación cardíaca tienen una alta prevalencia de EVs y trastornos del sistema de conducción.

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An 18-year-old girl had been suffering from palpitations for 3 years. After a normal and asymptomatic pregnancy, she became highly symptomatic with more than 6 tachycardia paroxysms a week, many of them requiring emergency hospitalizations because of hemodynamic collapse. The electrophysiological evaluation revealed dual A-V nodal pathways and the presence of 4 accessory pathways (3 in the left A-V ring: lateral, posterior, and posteroseptal, 1 right posteroseptal) with 5 types of atrioventricular tachycardia and atrial flutter. The 4 accessory pathways and the slow A-V nodal pathway were successfully ablated, and the patient has been asymptomatic for 12 months without taking antiarrhythmic drugs.

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