Importancia del mapeo óptico de cultivos de cardiomiocitos HL-1 en estudios electrofisiológicos / Importance of the optical mapping of HL-1 cardiomyocyte cultures in electrophysiological studies

Introducción: El desarrollo de herramientas para investigar la actividad electrofisiológica cardiaca ha permitido profundizar en el conocimiento sobre los mecanismos subyacentes a las arritmias cardiacas. Los sistemas de mapeo óptico constituyen una tecnología que responde a la necesidad de superar varios obstáculos en la experimentación. Objetivo: Proporcionar una visión general de la importancia del mapeo óptico en cultivos celulares HL-1, en las investigaciones en electrofisiología cardiaca. Métodos: Se realizó una revisión sobre los estudios electrofisiológicos que involucran la línea celular HL-1 utilizando la técnica de mapeo óptico. Conclusiones: Los trabajos se caracterizan por la implementación de la técnica respecto a la tecnología de los equipos de mapeo, a la utilización de diferentes colorantes y al objetivo de la investigación. Están enfocados en el estudio de mecanismos arritmogénicos, procesos de estiramiento mecánico o remodelación del tejido y en el análisis de nuevos biomateriales. Lo anterior, sustenta la relevancia del mapeo óptico en la investigación cardiaca(AU)

Introduction: The development of tools to study cardiac electrophysiological activity has made it possible to broaden knowledge about the mechanisms underlying cardiac arrhythmias. Optical mapping systems constitute a technology that responds to the need to overcome several hurdles in experimentation. Objective: Provide an overview of the importance of optical mapping in HL-1 cell cultures in cardiac electrophysiology research. Methods: A review was conducted of electrophysiological studies involving the HL-1 cell line using the optical mapping technique. Conclusions: The studies are characterized by implementation of the technique with respect to the technology of mapping equipment, the use of different colorants and the purpose of the research. They focus on the study of arrhythmogenic mechanisms, mechanical stretch processes or tissue remodeling as well as the analysis of new biomaterials. The above substantiates the relevance of optical mapping in cardiac research(AU)

Analysis of Conduction Intervals in Normal Electrophysiological Studies: Establishment of Reference Values the Brazilian Population

Abstract Background In the investigation of cardiac rhythm disorders, a normal electrophysiological (EPS) study is associated with a favorable prognosis. One of the normality criteria is established by conduction intervals within expected range. Objective To establish reference values in EPS for the intracavitary conduction intervals (PA, AH and HV) in a Brazilian population. Methods A retrospective cohort study of the first 1,500 patients submitted to EPS ablation was performed at Instituto de Cardiologia do Rio Grande do Sul, Brazil. The EPS was considered normal if the test was performed for diagnostic purpose; absence of induced arrhythmias; and conduction intervals within the expected range. The REDCap software was used for data collection and management, and the SPSS Statistics 22.0 used for data analysis. Continuous variables were compared with Student's t-test for independent samples and categorical variables with the chi-square test (X 2 ). Values of p ≤ 0.05 were considered significant. Results A total of 124 (8.3%) with EPS considered normal were included; mean age was 52 ± 21 years, and 63 were male. The mean values in milliseconds of PA, AH and HV were 23 ± 9, 88 ± 25 and 44 ± 7, respectively. The PA, AH, and HV percentile ranges were 13 - 25, 81-107 and 40 - 52, respectively. When the patients were divided into three age groups (1 to 18 years, 19 to 64 years and 65 or more), we observed that the group of older patients had significantly higher values of PA, AH and HV compared with younger patients. Conclusion This study showed that intracavitary conduction intervals in a sample of the Brazilian population were similar to previously published studies. Elderly patients tend to have higher values of intracavitary conduction intervals in EPS. Future studies including broader age ranges could enable the acquisition of more reliable and reproducible reference values. (Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0)

Duración de la onda P en las 12 derivaciones del electrocardiograma y su relación con el tiempo de conducción interauricular en pacientes con taquicardias paroxísticas supraventriculares / P wave duration in the 12 leads of the electrocardiogram and its relationship with interatrial conduction time in patients with paroxysmal supraventricular tachycardias

RESUMEN Introducción: Existen algunos estudios que relacionan parámetros de la onda P con diferentes tiempos de conducción auricular, pero no se han realizado teniendo en cuenta a cada derivación del electrocardiograma. Objetivo: Determinar la duración de la onda P (Pdur) en las 12 derivaciones y relacionarlas con el tiempo de conducción interauricular. Método: Estudio de corte transversal en 153 pacientes adultos con diagnóstico confirmado de taquicardia por reentrada intranodal (TRIN) o vías accesorias mediante estudio electrofisiológico invasivo. Resultados: Al comparar la Pdur entre sustratos arrítmicos por cada derivación, no existieron diferencias significativas, excepto en V6. En las derivaciones DII, DIII, aVR, aVF, V1 y de V3-V6 la Pdur se correlacionó con el tiempo de conducción interauricular en ambos sustratos arrítmicos. En el análisis multivariado, la Pdur constituyó un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil, en las derivaciones de cara inferior y en V3, V5 y V6. Se observaron altos valores del área bajo la curva de la Característica Operativa del Receptor en las derivaciones DII (0,950; p<0,001), DIII (0,850; p<0,001) y V5 (0,891; p<0,001). Conclusiones: No existen diferencias por derivación en la Pdur al comparar casos con TRIN y vías accesorias, excepto en V6. La mayoría de las derivaciones se correlacionaron con el tiempo de conducción interauricular. La Pdur fue un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil. La derivación DII presenta la mayor capacidad discriminativa para encontrar valores prolongados del tiempo de conducción interauricular.

ABSTRACT Introduction: Although some studies relate P wave parameters to different atrial conduction times, they do not consider each electrocardiogram lead separately. Objective: To determine the duration of P wave (Pdur) in the 12 leads of the electrocardiogram and relate it to the interatrial conduction time. Method: We conducted a cross-sectional study in 153 adult patients with confirmed diagnosis of atrioventricular nodal reentry tachycardia (AVNRT) or accessory pathways by invasive electrophysiological study. Results: When comparing the Pdur between arrhythmic substrates by each lead, no significant differences were found, except for V6. In leads II, III, aVR, aVF, V1 and V3-V6, Pdur was correlated with the interatrial conduction time in both arrhythmic substrates. In our multivariate analysis, the Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile in inferior wall leads and in V3, V5 and V6. High values of the area under the receiver operating characteristic curve were observed in II (0.950; p<0.001), III (0.850; p<0.001) and V5 (0.891; p<0.001) leads. Conclusions: The Pdur showed no difference by leads when comparing cases with AVNRT and accessory pathways, except for V6. Most of the leads were correlated with the interatrial conduction time; Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile. Lead II has the greatest discriminatory ability to find prolonged values of interatrial conduction time.

Regulación autonómica cardiovascular durante la prueba del peso sostenido en pacientes sanos y diabéticos tipo 2 / Autonomic cardiovascular regulation during the sustained weight test in healthy subjects and type 2 diabetic patients

Introducción: En la actualidad se hace imprescindible el estudio de la diabetes mellitus tipo 2 a partir de técnicas poco costosas en función de la carga sanitaria que representa, es entonces donde la prueba del peso sostenido gana valor como ejercicio isométrico estático cubano en el estudio de la variabilidad de la frecuencia cardíaca. Objetivo: Determinar las respuestas electrofisiológicas autonómicas y hemodinámicas en estado basal y durante la prueba del peso sostenido en pacientes sanos y con diabetes tipo 2. Métodos: Se realizó un estudio en la Universidad de Ciencias Médicas de Santiago de Cuba, no observacional, cuasi-experimental, de tipo antes-después con grupo control de 60 pacientes (30 sanos y 60 con diabetes mellitus tipo 2). Resultados: Los diabéticos presentaron mayor IMC (p = 0,004). En estado basal se experimentaron diferencias significativas entre pacientes sanos y diabéticos. En la mayoría, los parámetros de la variabilidad de la frecuencia cardíaca analizados y durante la prueba del peso sostenido, solo se observaron diferencias significativas en las variables TAS (p = 0,022), BF (p = 0,001) y AF (p = 0,015). Al realizar la prueba del peso sostenido se encontraron variaciones muy significativas (p < 0,001) de los parámetros hemodinámicos, y variaciones significativas de AF (p = 0,023) y BF/AF (p = 0,046) en pacientes sanos; y en diabéticos, diferencias significativas de las variables hemodinámicas. Conclusiones: Se determinó una menor respuesta en pacientes diabéticos con respecto a los sanos del sistema nervioso autónomo, lo que expresa un deterioro de este y una disminución de la actividad simpática y parasimpática(AU)

Introduction: At present it is indispensable to study type 2 diabetes mellitus with low-cost techniques due to the health load it represents. In this context the sustained weight test acquires great value as a Cuban static isometric exercise for the study of heart rate variability. Objective: Determine autonomic and hemodynamic electrophysiological responses at baseline state and during the sustained weight test in healthy subjects and type 2 diabetic patients. Methods: A non-observational quasi-experimental before-after study was conducted at the University of Medical Sciences of Santiago de Cuba based on a control group of 60 patients (30 healthy and 30 with type 2 diabetes mellitus). Results: Diabetics had a higher BMI (p = 0.004). At baseline state significant differences were found between healthy subjects and diabetic patients. In most of the heart rate variability parameters analyzed and during the sustained weight tests, the only variables that showed significant differences were SBP (p = 0.022), FB (p = 0.001) and FA (p = 0.015). The results obtained from the sustained weight test were the following: very significant variations of hemodynamic parameters (p < 0.001), significant FA (p = 0.023) and FB/FA (p = 0.046) variations in healthy subjects, and significant differences in hemodynamic variables in diabetic patients. Conclusions: A lower response by the autonomic nervous system was determined in diabetic patients versus healthy subjects, signaling deterioration of that system and reduced sympathetic and parasympathetic activity(AU)

Evaluation of left atrial function in asymptomatic dogs with chronic myxomatous mitral valve disease: two-dimensional feature-tracking echocardiography and Simpsons monoplanar methods / Avaliação da função atrial esquerda em cães assintomáticos com degeneração mixomatosa crônica de valva mitral: métodos ecocardiográficos bidimensional feature tracking e monoplanar de Simpson

The present study evaluated the volume and function of the left atrium by two-dimensional echocardiographic feature-tracking imaging (2D-FTI) and Simpson's monoplanar modeling in dogs with asymptomatic degenerative mitral valve disease (DMVD). The study consisted of 80 dogs that were divided into the following three groups: Group 1, 21 dogs (A); Group 2, 30 dogs (B1) and Group 3, 29 dogs (B2). The variable strain (contraction phase) was significantly lower in Group 3 than in Group 1 (12.92±4.54 x 16.69±5.74, p=0.014), and significant differences in the contraction strain index (CSI) were observed between all of the groups that were evaluated (1 = 46.82±8.10, 2 = 39.88±8.03, 3 = 35.25±5.64, p<0.0001). The atrial diastolic volume index (AdVi) that was measured by 2D-FTI was significantly higher in Group 3 than in Group 1 (1.31±0.95 x 0.96±0.31, p=0.038), and the atrial cardiac index (ACI) was also higher in Group 3 than in Group 1 (102.38±80.18 x 78.19±33.38, p=0.030). Atrial function was assessed by Simpson's monoplanar method, which demonstrated an increase in the left atrial systolic volume, while the contractile function decreased with an increasing disease severity (Group 1 0.21±0.06; Group 2 0.25±0.06; Group 3 0.32±0.08, p<0.0001). The intraobserver and interobserver assessments showed low to moderate variability; most of the values for the coefficient of variation for the variables that were analysed with each method were below 25%. Thus, DMVD was determined to cause an alteration in atrial function, especially in the contraction phase, and even in asymptomatic animals, and the methods of 2D-FTI echocardiography and Simpson's monoplanar evaluation are sensitive and early methods for the detection of left atrial dysfunction.(AU)

O presente estudo avaliou o volume e a função atrial esquerda obtidos por meio da ecocardiografia bidimensional feature tracking (2D-FTI) e pelo método monoplanar de Simpson em cães saudáveis e cães com DMVD assintomáticos. Foram avaliados 80 cães distribuídos em três grupos: Grupo 1, 21 cães (classe A); Grupo 2, 30 cães (classe B1) e Grupo 3, 29 cães (classe B2). A variável strain (fase de contração) foi significativamente menor no Grupo 3 que no Grupo 1 (12,92±4,54 x 16,69±5,74, p=0,014) e para a variável índice de strain de contração (CSI), houve diferença estatística entre todos os grupos avaliados (1 = 46,82±8,10; 2 = 39,88±8,03; 3 = 35,25±5,64, p<0,0001). O índice de volume diastólico atrial (iVdA) mensurado por meio do 2D-FTI foi significativamente maior no Grupo 3 que no Grupo 1 (1,31±0,95 x 0,96±0,31, p=0,038), assim como para o índice cardíaco atrial (iCA) também foi maior no Grupo 3 (102,38±80,18 x 78,19±33,38, p=0,030). A função atrial avaliada pelo método monoplanar de Simpson demonstrou um aumento do volume atrial esquerdo e do volume sistólico do átrio esquerdo, enquanto que a função contrátil diminuiu com o aumento da gravidade da doença (Grupo 1 0,21±0,06; Grupo 2 0,25±0,06; Grupo 3 0,32±0,08; p<0,0001). A avaliação intraobservador e interobservador, demonstrou variabilidade baixa a moderada, uma vez que a maioria dos valores de coeficiente de variação se concentraram abaixo de 25% para as variáveis analisadas em ambos os métodos. Dessa forma, conclui-se que a DMVD causa alteração na função atrial, principalmente na fase de contração, mesmo em animais assintomáticos e que a ecocardiografia 2D-FTI e o método monoplanar de Simpson são métodos sensíveis e precoces na detecção da disfunção atrial esquerda.(AU)

Crioablación en taquicardia ortodrómica por vía accesoria oculta parahisiana: caso clínico y revisión de la literatura / Crioablation of orthodromic supraventricular tachycardia win an occult accessory pathway

Abstract An 18-year-old woman with recurrent tachycardia was shown to have orthodromic supraventricular tachycardia through an antero-septal occult pathway near the His. Cryoablation was selected to avoid A-V block. The accesory pathway was finally interrupted after 360 sec of cryoablation. No recurrence was documented after a 12 month follow-up

Mapeo y ablación exitosa, desde el interior de la vena cardíaca magna, de extrasístoles ventriculares originados en el techo (summit) del ventrículo izquierdo / Mapping and successful ablation, from within the great cardiac vein, of premature ventricular contractions originating from the summit of the left ventricle

RESUMEN Se presenta el caso de una paciente de 43 años, con antecedentes de salud aparente, hasta varias semanas previas a su ingreso, cuando comenzó a presentar síncopes precedidos de palpitaciones. Se realizó estudio electrofisiológico y se demostró precocidad en la porción distal del electrodo de registro de seno coronario, que corresponde a la vena cardíaca magna (interventricular anterior) y techo (summit) del ventrículo izquierdo. A pesar del excelente registro precoz se estudiaron estructuras vecinas como el tracto de salida del ventrículo izquierdo en la cúspide coronaria izquierda, aquí el mapeo eléctrico (pace mapping) no fue concordante total. En el sitio de la precocidad obtenida dentro del sistema venoso cardíaco se realizó mapeo concordante 100%, con una precocidad del catéter de ablación de -30 milisegundos. Se decidió ablación con incrementos progresivos de temperatura y potencia con corte de impedancia (termomapping) y se logró el éxito de la ablación sin reproducibilidad de la arritmia y excelente evolución posterior.

ABSTRACT The case of a 43-year-old female patient is presented, with an apparent history of good health, up to several weeks prior to admission, when she began to present syncopes preceded by palpitations. An electrophysiological study was performed and prematurity in the distal portion of the coronary sinus recording electrode was demonstrated, which corresponds to the great cardiac vein (anterior interventricular vein) and summit of the left ventricle. Despite the excellent early registration, neighboring structures were studied, such as the left ventricular outflow tract in the left coronary cusp, here the pace mapping was not totally concordant. At the site of the precocity obtained within the cardiac venous system, a 100% concordant mapping was achieved, with an ablation catheter's precocity of -30 milliseconds. The ablation was decided with progressive increases in temperature and power with thermomapping and the success of the ablation was achieved without reproducibility of the arrhythmia and excellent subsequent evolution.

The effect of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) on mice myocardial morphology / O efeito do 1-metil-4-fenil-1, 2, 3, 6 tetrahidropiridina (MPTP) na morfologia do miocárdio de camundongo

Studies have demonstrated sympathetic cardiac denervation in the MPTP mouse model. MPTP toxicity causes sympathetic nerve damage and depletion of heart norepinephrine. Previous evaluations of impairments in heart innervation have been based on imaging, electrophysiological and biochemical methods. However, these studies lacked information that can be obtained from morphoquantitative analyses. Thus, this study aimed to apply a design-based stereological method for evaluating the morphoquantitative alterations of myocardium following treatment with the neurotoxin MPTP in the C57/BL mouse. Our results showed that MPTP reduced the number of cardiomyocytes in the left ventricle.(AU)

Estudos têm demonstrado a desnervação simpática cardíaca no modelo da administração do MPTP em camundongo. A toxicidade do MPTP causa lesão ao nervo simpático e depleção da norepinefrina. As avaliações dos danos na inervação do coração são baseadas em métodos de imagem, eletrofisiológico e bioquímico. Contudo, estes estudos carecem de informações provenientes de análises morfoquantitativas. Assim, objetivou-se aplicar métodos estereológicos para avaliar as alterações morfoquantitativas do miocárdio após o tratamento com a neurotoxina MPTP no camundongo C57/BL. Nossos resultados mostraram que o MPTP causa redução no número de cardiomiócitos no ventrículo esquerdo.(AU)

Video Caso Clínico: Estimulación Vagal Directa Como Maniobra Electrofisiológica Alternativa en el Diagnóstico de Taquicardia Durante Estudio Electrofisiológico / Case Report: Direct Vagal Stimulation as Alternative Electrophysiological Procedure in the Diagnosis of Tachycardias During Electrophysiological Study

INTRODUCCIÓN: El síndrome de Wolff Parkinson White se caracteriza por la conexión anómala entre la aurícula y el ventrículo durante el paso del estímulo sinusal, generalmente causada por una vía accesoria que conecta el músculo auricular con el músculo ventricular llamado haz de Kent, caracterizándose por la presencia de síntomas como: palpitaciones, sincope o muerte súbita y sumado a la presencia de onda delta, intervalo PR corto, QRS ancho y alteraciones de la repolarización ventricular en el electrocardiograma. El estudio electrofisiológico tiene como objetivo confirmar la presencia, localización y características de este haz anómalo y posteriormente, con seguridad, proceder a la ablación por radiofrecuencia eliminando esta vía accesoria, siendo considerado un procedimiento curativo en el caso del síndrome de Wolff Parkinson White. Durante el estudio se realiza estimulaciones eléctricas en los sitios específicos, tanto de la aurícula como del ventrículo, además se utiliza medicación intravenosa como la adenosina que actúa bloqueando al nódulo aurículoventricular y así observar el paso residual de la estimulación sinusal normal y/o el paso retrogrado del estímulo ventricular hacia la aurícula a través del haz de Kent, permitiendo de esta forma analizar las características de las conexiones aurículoventriculares previo a la ablación. La posibilidad de realizar una estimulación vagal selectiva de alta frecuencia y baja amplitud a nivel infraorbitario, descrita por Pachón et al [1], a través de la vena yugular interna y el consecuente bloqueo aurículoventricular transitorio que esta ocasiona, permite realizar el estudio sin necesidad de utilizar otras maniobras electrofisiológicas o medicación endovenosa

BACKGROUND: Wolff Parkinson White Syndrome is characterized by the bypass of the electrical signal through an abnormal pathway, different from the atrioventricular node that connects the atrial and ventricular muscles (Bundle of Kent). It presents with palpitations, syncope or can even cause sudden death. Electrocardiogram findings consist on Delta waves, shortened PR interval, widened QRS complex and altering of the ventricular repolarization. In the presence of Ventricular pre-excitation (Wolff Parkinson White Syndrome), the electrophysiological testing is key to confirm the presence, site and features of this accessory pathway. Later, with the certainty of the diagnosis proceed to perform the Radiofrequency Ablation, the definitive treatment to eliminate this abnormal pathway. This test is usually done with the use of electrophysiological maneuvers, stimulating key sites in the atria and the ventricle, with the help of intravenous drugs like Adenosine. The objective is to block the AV node to look how the remnants of the normal electrical signal move through the abnormal pathway, thus letting the physician analyze the characteristics previously mentioned of this pathway. After the ablation, these maneuvers are repeated to confirm the complete elimination of the accessory pathway that has direct relation with the prognostic. Based on the possibility of high frequency and low amplitude selective vagal stimulation described by Pachón et al [1], at infraorbital level through the internal jugular vein and the resulting transitory atrioventricular block. It is possible to study the abnormal pathway without the need of electrophysiological maneuvers or the use of IV drugs, either pre or post ablation.

Taquicardia ventricular polimórfica catecolaminérgica com necessidade de implante de cardiodesfibrilador implantável (CDI): Um relato de caso / Ventricular Catecolaminergic Polymorphic Tachycardia (VCPT) with ICD implantation requirement: A case report

Relato de caso de uma paciente do sexo feminino, com 16 anos de idade à ocasião de sua admissão no Instituto de Cardiologia. A mesma foi encaminhada por serviço de saúde externo devido a síncopes durante atividade física e foi submetida à investigação, com diagnóstico final de taquicardia ventricular catecolaminérgica. Após a definição diagnóstica, foi realizado tratamento medicamentoso com betabloqueador, sendo necessário o implante de marcapasso definitivo por conta da incompetência cronotrópica secundária ao tratamento farmacológico instituído. Posteriormente, por persistência das arritmias ventriculares mesmo com o uso de terapia otimizada, optou-se por realizar um implante de CDI

Case report of a 16-year-old female patient at the time of her admission to the Institute of Cardiology. She was referred by an external healthcare service due to syncope during physical activity and was submitted to the investigation with a final diagnosis of catecholaminergic ventricular tachycardia. Once the diagnosis was established, the patient was administered a beta-blocker and definitive pacemaker implant was required due to chronotropic incompetence secondary to drug therapy. Subsequently, due to the persistence of ventricular arrhythmias despite the use of optimized therapy, we decided to implant an ICD

Características electrocardiográficas de vías fascículo-ventriculares en pediatría: estudio comparativo con las vías accesorias anteroseptalesderechas / Electrocardiographic characteristics of fasciculo-ventricular accessory pathways in children: A comparative study with right anteroseptal accessory pathways

Resumen Objetivos: Las vías accesorias (VAc) fascículo-ventriculares (FV) tienen una localización anatómica similar a las VAcanteroseptales derechas (ASD) y comparten características electrocardiográficas. El objetivo es comparar características electrocardiográficas de las VAC FV con las de las ASD en pediatría. Métodos: Se incluyeron pacientes con preexcitación manifiesta sometidos a estudio electrofisiológico. Las VAc FV se definieron por un intervalo HV ≤ 32ms y un alargamiento del AH sin modificación del HV, del grado o patrón de preexcitación ventricular durante la estimulación auricular. Tres observadores independientes y ciegos analizaron los ECG en cada grupo. Resultados: De 288 pacientes, 15 (5.2%) presentaban VAC FV y 14 VAC ASD (4.9%). El intervalo PR fue más largo en las VAc FV que en las ASD (113 ± 21 vs. 86 ± 13 ms respectivamente; p = < 0.001) y la duración del QRS fue menor (95 ± 12 vs. 137 ± 24 ms respectivamente; p = < 0.001). El ECG de las VAc FV presentó una deflexión rápida de baja amplitud previa al inicio del QRS en 13 de 15 pacientes (87%) y en 2 con VAc AV ASD (14%); (p = 0.003). Conclusiones: El intervalo PR fue más largo y el complejo QRS más angosto en la VAC FV respecto de las ASD. La presencia de una deflexión rápida de baja amplitud previa al inicio del QRS permitiría diferenciarlas de las aurículo-ventriculares ASD de manera no invasiva.

Abstract Objectives: Fasciculo-ventricular (FV) accessory pathways (AP's) and right anteroseptal (RAS) AP's share similar anatomic locations and electrocardiographic characteristics. The objective of this article is to compare these features in children. Methods: All patients with manifest pre-excitation who underwent an electrophysiological study were included. Fasciculo-ventricular AP's were defined by the presence of an HV inter- val ≤ 32 ms and a prolongation of the AH without changes in the HV interval, or the level of pre-excitation during atrial pacing. Three independent and blind observers analysed the ECG's in both groups. Results: Out of 288 patients, 15 (5.2%) had FV AP's and 14 (4.9%) right AS AP's. The PR interval was longer in FV AP's than in RAS (113 ± 21 vs 86 ± 13 ms respectively; P < .001) and the QRS was narrower (95 ± 12 vs 137 ± 24 ms respectively; P < .001). The ECG in patients with FV AP's showed a rapid low amplitude deflection at the begining of the QRS in 13 out of 15 patients (87%) and in 2 (14%) the RAS AP group (P = .003). Conclusions: The PR interval was longer and the QRS complex was narrower in patients with FV AP's. The presence of a rapid low amplitude deflection at the beginning of the QRS complex would allow to differentiate them from RAS AP's non-invasively.

Conceptos actuales sobre la clasificación clínica y alteraciones electrofisiológicas en la disfunción del nódulo sinusal / Current concepts about the clinical classification and electrophysiological alterations in the sinus node dysfunction

La disfunción del nódulo sinusal (DNS) es generalmente secundaria a la senescencia del nodo sinusal y del miocardio auricular circundante. Los pacientes con este trastorno son a menudo añosos y en general presentan otras comorbilidades. Los pacientes a menudo buscan atención médica con síntomas de aturdimiento, pre-síncope, síncope y, en pacientes con periodos alternantes de bradicardia y taquicardia, palpitaciones u otros síntomas asociados con una frecuencia cardíaca rápida. Debido a que los síntomas pueden ser de naturaleza variable, inespecíficos y frecuentemente transitorios, a veces puede ser difícil establecer esta relación síntoma-alteración electrocardiográfica. Los hallazgos electrocardiográficos típicos son uno o más episodios de bradicardia sinusal extrema (Rubenstein Tipo I), o pausas sinusales, paro y bloqueo de salida sinoatrial (Rubenstein Tipo II), o episodios de bradicardia y/o pausas alternantes con taquiarritmias auriculares (Rubenstein Tipo III). Las investigaciones basadas en el registro de electrogramas locales auriculares anormalmente prolongados y fraccionados durante el ritmo sinusal y su distribución característica en la aurícula derecha de pacientes con DNS han aportado un conocimiento importante sobre las propiedades electrofisiológicas de la aurícula patológica. El electrograma auricular anormal traduce una conducción auricular irregular, caracterizada por una actividad eléctrica local no homogénea, relacionada con una conducción anisotrópica, no uniforme y retardada a través de un miocardio auricular patológico, en el que se pueden originar arritmias por reentrada. La detección de electrogramas auriculares anormales en la DNS identifica a un grupo de pacientes con vulnerabilidad auricular aumentada y con una incidencia significativamente mayor de episodios espontáneos o inducidos de fibrilación auricular(AU)

Sinus node dysfunction (SND) is often secondary to senescence of the sinus node and surrounding atrial myocardium. Patients with this disorder are frequently elderly and generally have other comorbidities. Patients with SND often seek medical attention with symptoms of lightheadedness, presyncope, syncope, and, in patients with alternating periods of bradycardia and tachycardia, palpitations and/or other symptoms associated with a rapid heart rate. Because symptoms may be variable in nature, nonspecific, and frequently transient, it may be challenging at times to establish this symptom-rhythm relationship. Typical electrocardiographic findings are one or more episodes of extreme sinus bradycardia (Rubenstein type I), or sinus pauses, arrest, and sinoatrial exit block (Rubenstein type II), or alternating bradycardia and atrial tachyarrhythmias (Rubenstein type III). Investigations based on the recording of abnormally prolonged and fractionated local atrial electrograms during sinus rhythm and their characteristic distribution in the right atrium of patients with SND have provided important knowledge about the pathological atrium electrophysiological properties. Abnormal atrial electrogram results in an irregular atrial conduction, characterized by a non-homogeneous local electrical activity, related to an anisotropic, non-uniform and delayed conduction through a pathological atrial myocardium, in which reentry arrhythmias may arise. Abnormal atrial electrograms detection in SND identifies a group of patients with increased atrial vulnerability and a significantly higher incidence of spontaneous or induced episodes of atrial fibrillation(AU)

Extrasístoles ventriculares: relación deflexión intrinsecoide / QRS para discriminar el origen / Ventricular extrasystoles: QRS intrinsiccoid deflection relationship to discriminate the origin

Introducción: las taquicardias ventriculares (TV) y complejos ventriculares prematuros (CVP) de los tractos de salida (TS) son arritmias ventriculares más frecuentes que se producen en el corazón estructuralmente sano. El manejo intervencionista con ablación es el tratamiento que en casos seleccionados ha demostrado tener mayor efectividad terapéutica; para optimizar el lugar de ablación sobre el foco de origen se han conformado ayudas complementarias a los estudios de extensión. Objetivo: proponer una herramienta para discriminar tempranamente el origen de las extrasístoles ventriculares provenientes de los tractos de salida a partir del cálculo del valor de la relación deflexión intrinsecoide/QRS medida en extrasístoles ventriculares en V6. Materiales y métodos: se realizó un estudio de corte transversal, en pacientes con diagnóstico de CVP llevados a estudio electrofisiológico más ablación exitosa. Se midió la deflexión intrinsecoide y se relacionó con el tiempo total del QRS en V6. Resultados: a partir de los análisis de los puntos del corte se estableció un valor de la relación deflexión intrisecoide/qrs menor o igual a 0.67 para el ventrículo derecho y mayor o igual a 0.68 para el ventrículo izquierdo. El análisis de los datos registró una correcta clasificación de los pacientes en el 80% de los casos. Conclusiones: este estudio propone una herramienta corta y sencilla de aplicar, que intenta predecir el origen de estas arritmias a partir de unas mediciones realizadas en un electrocardiograma en que se muestre dicha extrasístole ventricular en V6, en donde es obtener posible origen del foco arritmogénico antes del procedimiento intervencionista.

ntroduction: outflow tract ventricular tachycardia (VT) and premature ventricular complexes (PVC) are common ventricular arrhythmias that occur in the structurally normal heart. Interventional management using ablation procedures in selected cases has demonstrated good therapeutic efficacy; diagnostic aids supplementary to extensión studies have been designed to optimize the target ablation site based on the site of origin. Objective: to propose a tool for early diagnosis of ventricular extrasystoles originating at the outflow tracts by calculating the time to intrinsicoid deflection / QRS measured in lead V6. Materials and Methods: a cross sectional study conducted in patients diagnosed with PVC who underwent an electrophysiological evaluation and a successful ablation procedure. We measured the time to intrinsicoid deflection or onset of the QRS complex to the peak of the R wave in V6. Results: the value of the intrinsicoid deflection /QRS time resulting from the cut off points analysis was less than or equal to 0.67 for the right ventricle and greater than or equal to 0.68 for the left ventricle. Data analysis provided a correct classification of patients in 80% of cases. Conclusions: this study proposes a short and simple predictive tool of the site of origin of these arrhythmias by measuring some electrocardiographic features showing said ventricular extrasystoles in V6, where it is possible to identify the site of origin of arrhythmias prior to an interventional procedure.

Association of Complex Fractionated Electrograms with Atrial Myocardial Thickness and Fibrosis

BACKGROUND AND OBJECTIVES: Although ablation of complex fractionated atrial electrograms (CFAE) in atrial fibrillation (AF) is one of the strategies for atrial substrate modification, the mechanism behind CFAE as an electrophysiological substrate remains unclear. We investigated structural differences between CFAE sites and their matched non-CFAE sites by comparing their histopathologic characteristics in canine AF models. METHODS: Atrial electrograms of four dogs were obtained from the epicardial site. AF was induced through burst atrial pacing at 600 bpm for 30 min. CFAE sites were identified during AF according to patterns visualized on the electrograms, and their matched non-CFAE sites were selected in the adjacent region, within 5 mm of each CFAE site. Tissues were harvested from CFAE sites and their matched non-CFAE sites at various locations in both atria. Histopathologic differences were identified between CFAE and non-CFAE sites. RESULTS: A total of 24 atrial tissues (12 with CFAE, 12 with non-CFAE) were evaluated. The atrial myocardium was significantly thicker at CFAE sites (1757.5±560.5 µm) than at non-CFAE sites (1279.5±337.2 µm) (p=0.036). At CFAE sites, it was filled with a significantly larger amount of fibrotic tissue than at non-CFAE sites (22.8±6.9% versus 7.2±4.7%, p < 0.001). Results were consistent across various tissue locations. The distribution of autonomic nerve innervation was similar between CFAE and non-CFAE sites. CONCLUSION: This study provides a better understanding of histological characteristics of CFAE sites, namely a thicker wall and greater amount of fibrosis. These findings may be associated with the development of CFAE and its pathophysiological contribution to AF.

Taquicardia ventricular polimórfica durante teste de inclinação na doença de Chagas / Polymorphic ventricular tachycardia during tilt testing in Chagas disease

Paciente do sexo masculino, de 62 anos de idade, com megacólon chagásico sem manifestações cardíacas, apresentou evento sincopal sem pródromos, sendo submetido a Holter de 24 horas, ecocardiografia, teste ergométrico e cineangiocoronariografia, que se mostraram normais. O estudo eletrofisiológico mostrou ausência de distúrbios de condução e de indução de taquiarritmias. Durante a fase basal do teste de inclinação, o paciente apresentou taquicardia ventricular polimórfica. Foi realizado implante de cardioversor-desfibrilador implantável. Na evolução, apresentou deterioração da função ventricular com início de terapêutica específica. Após sete anos de acompanhamento, observaram-se três episódios de taquicardia ventricular polimórfica adequadamente revertidos pelo cardioversor-desfibrilador implantável

A 62 year-old man with Chagasic megacolon without cardiac manifestations developed a syncope without prodrome and was submitted to 24-hour Holter monitoring, echocardiogram, exercise test and coronary angiography. Electrophysiology tests showed there was no conduction and tachyarrhythmia induction disorders. During the baseline phase of the tilt test, the patient presented a polymorphic ventricular tachycardia. An implantable cardioverter defibrillator was implanted. At the follow-up, the patient presented left ventricular deterioration and specific therapy was started. After seven years of follow-up, three episodes of polymorphic ventricular tachycardia were observed and were successfully converted

Local Atrial/Ventricular Ratio as an Adjuvant Marker for Catheter Ablation of Atrioventricular Accessory Pathways

BACKGROUND AND OBJECTIVES: The earliest atrial (A)/ventricular (V) activation potential, or accessory pathway (AP) potential are commonly used as ablation targets for atrioventricular (AV) APs. However, these targets are sometimes ambiguous. SUBJECTS AND METHODS: We reviewed 119 catheter ablation cases in 112 patients diagnosed with orthodromic atrioventricular reentrant tachycardia (AVRT) or Wolff-Parkinson-White (WPW) syndrome. Local A/V amplitude potentials with the earliest activation or AP potential were measured shortly before achieving antegrade AP conduction block, ventriculoatrial block during right ventricle (RV) pacing, or AVRT termination with no AP conduction. RESULTS: APs were located in the left lateral (55.5%), left posterior (17.6%), left posteroseptal (10.1%), midseptal (1.7%), right posteroseptal (7.6%), right posterior (1.7%), and right lateral (5.9%) regions. The mean earliest activation time was 16.7±15.5 ms, mean A/V potential was 1.1±0.9/1.0±0.9 mV, and mean A/V ratio was 1.7±2.0. There was no statistically significant difference between the activation methods (antegrade vs. RV pacing vs. orthodromic AVRT) or AP locations (left vs. right atrium). However, when the local A/V ratio was divided into 3 groups (≤0.6, 1.0±0.3, and ≥1.4), the antegrade approach resulted in an A/V ratio greater than 1.0±0.3 (86.7%, p=0.007), and the orthodromic AVRT state resulted in a ratio of less than 1.0±0.3 (87.5%, p<0.001). CONCLUSION: The mean local A/V potential and ratio did not differ by activation method or AP location. However, a different A/V ratio based on activation method (≥1.0±0.3, antegrade approach; and ≤1.0±0.3, orthodromic AVRT state) could be a good adjuvant marker for targeting AV APs.

Association between clinical condition and F-waves changes in the acute phase of stroke / Associação entre condição clínica e alterações das ondas-F na fase aguda do acidente vascular cerebral

ABSTRACT Objective To relate F-waves with clinical and laboratory exams in the acute phase of stroke. Methods Inclusion criteria for this cross-sectional study were: hemiplegia, absence of previous cranial trauma, myopathy, diabetes, alcoholism or other known causes of peripheral neuropathy, and normal sensory and motor conduction. The National Institutes of Health Stroke Scale (NIHSS) score, glycemia, glucosilate hemoglobin, and CPK were obtained at admission by routine blood exams. After hospital admission, the F-wave latencies and persistence were obtained from the deep peroneal nerve using symmetrical techniques. Results Evaluation of 20 individuals – mean age 66 years, 50% male and 85% Caucasian – showed association of F-wave persistence with glycemia (r = 0.71; p < 0.001) and NIHSS categorized (NIHSS 1-7 = 65.0 x NIHSS 9-23 = 100; p = 0.004). Multivariate analysis found only association of F-wave persistence with glycemia β = 0.59 (0.44–0.74); p < 0.001. Conclusion The increase in the persistence of F-waves are associated with hyperglycemia in the acute phase of stroke.

RESUMO Objetivo Relacionar as ondas-F com exames clínicos e laboratoriais na fase aguda do acidente vascular cerebral (AVC). Os critérios de inclusão para este estudo transversal foram: hemiplegia, ausência de trauma craniano, miopatia, diabetes, alcoolismo ou outra causa conhecida de neuropatia periférica, além de condução sensorial e motora normal. O National Institutes of Health Stroke Scale (NIHSS), glicemia, hemoglobina glicada e CPK foram obtidos na admissão por meio de exames de rotina. Após a admissão hospitalar, a latência e persistência das ondas-F foram obtidas por meio da estimulação do nervo fibular profundo utilizando técnicas simétricas. Foram avaliados 20 indivíduos – média de idade 66 anos, 50% homem e 85% caucasianos – apresentaram associação univariada da persistência das ondas-F com glicemia (r = 0.71; p < 0.001) e NIHSS categorizado (NIHSS 1–7 = 65.0 x NIHSS 9-23 = 100; p = 0.004). Na regressão multivariada foi encontrado associação somente entre persistência de ondas-F com glicemia β = 0.59(0.44–0.74); p < 0.001. Conclusão O aumento da persistência de ondas-F está associado com maior nível de glicemia na fase aguda do AVC.

Crioablación: aplicaciones clínicas en la electrofisiología cardiaca a partir de sus bases biofísicas / Cryoablation: Clinical applications in cardiac electrophysiology from their biophysical bases

Resumen: La crioablación es una energía alternativa a la radiofrecuencia para la ablación de diferentes arritmias, en la que sus propiedades biofísicas únicas ofrecen un perfil de seguridad mayor. Desde su utilización para el tratamiento quirúrgico de diversas arritmias hasta su conceptualización en la técnica transcatéter actual, la crioablación ha probado no solo ser una fuente segura de energía, sino una fuente eficaz a largo plazo. Mientras que la radiofrecuencia ha sido la energía más utilizada para el aislamiento de venas pulmonares en la ablación de fibrilación auricular, los avances tecnológicos con criobalón han logrado simplificar el procedimiento sin sacrificar su eficacia. La crioablación ha sido ampliamente utilizada para arritmias localizadas en sitios de alto riesgo, como la ablación de la taquicardia por reentrada intranodal AV y vías accesorias septales por su nulo riesgo teórico de bloqueo AV completo. Esta revisión tiene la intención de dar a conocer las aplicaciones clínicas de la criotermia a través del entendimiento profundo de sus bases biofísicas.

Abstract: Cryoablation is an energy alternative to radiofrequency for ablation of various arrhythmias, where its unique biophysical properties offer a greater safety profile. Since its first use for the surgical treatment of different arrhythmias until its conceptualization in the current technical transcatheter, cryoablation has proven not to be only a safe source of energy, but also an effective source in the long-term. While the radiofrequency has been the energy most used for isolation of pulmonary veins in atrial fibrillation ablation, technological advances in cryoballon have managed to simplify the procedure without sacrificing its effectiveness. Cryoablation has been widely used for arrhythmias located in high-risk locations, such as the ablation of the atrioventricular nodal reentrant tachycardia and septal accessory pathways, due to its theoretical null risk of complete AV block. This review intends to give the clinical applications of the cryothermy through a thorough understanding of their biophysical basis.

Terapia de ressincronização cardíaca após implante por cateter debioprótese valvar aórtica / Cardiac resynchronization therapy after transcatheter aortic valve implantation

O tratamento da estenose aórtica com implante por cateter de bioprótese valvar aórtica é sabidamente eficaz. Contudo, os distúrbios de condução são complicações frequentes e associam-se a elevada taxa de implante de marcapasso definitivo. Questões referentes ao melhor modo de estimulação, ao papel do cardiodesfibrilador na profilaxia de morte súbita e ao prognóstico ainda não apresentam consenso. Relata-se, portanto, um caso de paciente que, após o implante valvar, evoluiu com bloqueio completo de ramo esquerdo agudo e bradiarritmia, insuficiência cardíaca refratária ao tratamento medicamentoso, com fração de ejeção gravemente comprometida e intolerância ao betabloqueador por bradiarritmia. Optou-se, então, pela terapia de ressincronização ao invésdo marcapasso convencional, com boa resposta clínica. A associação com cardiodesfibrilador foi descartada paraprofilaxia de morte súbita após o estudo eletrofisiológico, o qual não evidenciou instabilidade elétrica ventricular...

Treatment of aortic stenosis with valve of transcatheter implant is known to be effective. However, conduction disorders are common complications and are associated with a high permanent pacemaker implantation rate. Questions regarding the best pacing mode, the role of the defibrillator in sudden death prevention and prognosis, do not have consensus yet. We report, therefore, the case of a patient who developed complete blockage of acute left bundle branch and bradyarrhythmia, heart failure refractory to drug therapy, poor ejection fraction and intolerance to betablocker due bradyarrhythmias after valve implant. Thus, we chose resynchronizationtherapy instead of conventional pacemakers and obtained a good clinical response. The association with adefibrillator was ruled out for sudden death prevention after the electrophysiological study, which did not show ventricular electrical instability...