Bloqueo de rama alternante en una taquicardia supraventricular: ¿Cuál es el mecanismo subyacente? / Alternating bundle branch block in a supraventricular tachycardia: Which is the mechanism ?

El bloqueo de rama funcional durante una taquicardia supraventricular puede ser observado con longitudes de ciclo cortas y representa una respuesta fisiológica del sistema de conducción intraventricular por la existencia de conducción nodal auriculo ventricular acelerada. Presentamos el caso de un paciente joven con taquicardia reentrante aurículo-ventricular ortodrómica y bloqueo de rama alternante. Esta respuesta infrecuente se explica por el hallazgo obtenido durante el estudio electrofisiológico. Una conducción nodal aurículo-ventricular acelerada produce un frente de onda que despolariza las ramas durante sus períodos refractarios. Una vez que ocurrió el bloqueo en una de las ramas, dicho bloqueo persistió debido al fenómeno de linking, que es por conducción oculta retrógrada repetitiva de la rama contralateral. Después de la ablación transcatéter de una vía accesoria oculta lateral izquierda, el marcapaseo auricular rápido a la misma longitud de ciclo de la taquicardia, reprodujo la misma aberrancia observada durante la taquicardia. Este procedimiento demostró que el bloqueo de rama funcional fue debido a la longitud de ciclo corto y no a la presencia de una vía accesoria aurículo-ventricular.

Functional bundle branch block during a supraventricular tachycardia can be observed with shorter cycle lengths and represent a physiologic response by the specialized intraventricular conduction system to accelerated AV nodal conduction. The present case corresponds to a young patient with exercise induced orthodromic A-V reentrant tachycardia and alternating bundle branch block. This unusual response is explained by the finding obtained during the electrophysiology study. An accelerated AV nodal conduction made the depolarizing wave front reach the bundle branches during their refractory period. Once block in one bundle was stablished, block persisted due to the linking phenomenon that is repetitive retrograde concealed conduction from the contralateral bundle. After catheter ablation of a concealed left-sided accessory A-V pathway, rapid atrial pacing at the same cycle length of the tachycardia reproduced the same aberrancies observed during tachycardia. This response proved that functional bundle branch block is due to the short cycle length and not the presence of an accessory A-V pathway.

Fibrilação atrial durante taquicardia por reentrada nodal atrioventricular: achado sugestivo da presença de via superiorcomum nodal / Atrial fibrillation during atrioventricular nodal reentry tachycardia: a suggestive finding favoring the presence of the upper common nodal pathway

Na taquicardia por reentrada nodal atrioventricular, a necessidade do átrio para a manutenção da taquicardia é controverso. Descrevemos um caso de fibrilação atrial ocorrendo durante taquicardia por reentrada nodal atrioventricular sem afetar o ciclo da arritmia, e discutimos as evidências favorecendo a presença de umavia comum superior.

In Atrioventricular Nodal Reentry Tachycardia the requirement of the atrium for the maintenance oftachycardia is controversial. We describe a case of atrial fibrillation that occurred during Atrioventricular Nodal Reentry Tachycardia without affecting the arrhythmia cycle, and discuss the evidences favoring the presence ofan upper common pathway.

A cardiologia intervencionista nas arritmias supraventriculares / Interventional cardiology in supraventricular arrhythmias

As taquicardias supraventriculares são comuns na prática clínica e, apesar de raramente levarem a morte, são motivos de visitas frequentes a pronto-socorros, piora da qualidade de vida e elevados custos ao sistema de saúde. O tratamento medicamentoso, apesar de amplamente empregado, tem demonstrado eficácia limitada e seu uso a longo prazo encontra-se associado ao desenvolvimento de efeitos colaterais. O conhecimento dos mecanismos destas arritmias favoreceram o desenvolvimento de técnicas e tecnologias intervencionistas seguras e altamente eficazes no controle e na cura destas doenças. Vários estudos têm demonstrado o custo-efetividade, bem como a superior eficácia da ablação nas taquicardias paroxísticas supraventriculares e no flutter atrial quando comparada ao tratamento medicamentoso. Apesar de ainda não ser possível a cura da fibrilação atrial por meio da ablação, esta ferramenta tem se mostrado superior ao tratamento farmacológico no controle dos sintomas e nos casos paroxísticos, evidências apontam que a ablação é capaz de retardas a progressão da doença. A despeito deste conhecimento, algumas evidências apontam que, no Brasil, este recurso vem sendo subaproveitado. Este trabalho tem como objetivo revisar as indicações de ablação das arritmias supraventriculares, bem como fornecer noções técnicas destas ferramentas terapêuticas.

Supraventricular tachycardias are common in clinical practice and rarely lead to sudden death but are a frequent reason for visits to emergency rooms, poor quality of life and high costs to the health system. Drug treatment shown limited efficacy and its long-term use is associated with side effects. Knowledge of the mechanisms related to these arrhythmias favored the development of safe and highly effective interventional technologies in the control and cure of these diseases. Several studies have demosntrated the cost-effectiveness as well as the superior efficacy of catheter ablation in the treatment of paroxysmal supraventricular tachycardia and trial flutter when compared to medical therapy. Although results of catheter ablation of atrial fibrilation are modest, they are modest, they are superior to pharmalogical for symptoms control. This paper reviews the indications for ablation of supraventricular arrhythmias as well as provides technical notions regarding these therapeutic tools still under utilized in Brazil.

Tratamento farmacológico das arritmias em crianças: indicação e posologias / Pharmacologic management of arrhytmias in children: indication and dosage

A arritmia cardíaca pode ocorrer em qualquer idade, do feto ao adulto. As diferenças fisiológicas acarretam um comportamento da arritmia e da ação das drogas peculiares em cada faixa etária. A decisão terapêutica na população se torna difícil. Este artigo tem como objetivo enfatizar as características específicas na infância para o tratamento farmacológico das arritmias.

Predictors and Clinical Impact of Inappropriate Implantable Cardioverter-Defibrillator Shocks in Korean Patients

Limited data are available on inappropriate shocks in Korean patients implanted with an implantable cardioverter-defibrillator (ICD). We investigated the impact of inappropriate shocks on clinical outcomes. This retrospective, single-center study included 148 patients treated between October 1999 and June 2011. The primary outcome was a composite event of all-cause mortality or hospitalization for any cardiac reason. The median follow-up duration was 29 months (interquartile range: 8 to 53). One or more inappropriate shocks occurred in 34 (23.0%) patients. A history of atrial fibrillation was the only independent predictor of inappropriate shock (hazard ratio [HR]: 4.16, 95% confidence interval [CI]: 1.89-9.15, P < 0.001). Atrial fibrillation was the most common cause of inappropriate shock (67.7%), followed by supraventricular tachycardia (23.5%), and abnormal sensing (8.8%). A composite event of all-cause mortality or hospitalizations for any cardiac reason during follow-up was not significantly different between patients with or without inappropriate shock (inappropriate shock vs no inappropriate shock: 35.3% vs 35.4%, adjusted HR: 1.06, 95% CI: 0.49-2.29, P = 0.877). Inappropriate shocks do not affect clinical outcomes in patients implanted with an ICD, although the incidence of inappropriate shocks is high.

Cardiomiopatia dilatada secundária à taquicardia juncional recíproca persistente / Dilated cardiomyopathy secondary to persistentjunctional reciprocating tachycardia

Mulher apresentava taquicardia supraventricular persistente, refratária a tratamento farmacológico, com características eletrocardiográficas compatíveis com a taquicardia juncional recíproca persistente, incluindo ondas P negativas em derivações inferiores e intervalo RP' longo, com relação RP' / P'R>1. A paciente apresentava cardiomiopatia dilatada secundária à taquicardia persistente, com importante redução do diâmetro ventricular e melhora significativa da fração de ejeção do ventrículo esquerdo após ablação de via anômala.

A woman presented persistent supraventricular tachycardia refractory to pharmacological treatment and with electrocardiographic characteristics consistent with persistent junctional reciprocating tachycardia, including inverted P waves in lower leads and long RP’ interval with regard to the RP’/P’R>1. The patient also presented dilated cardiomyopathy secondary to persistent tachycardia, with a significant reduction of the ventricular diameter and important improvement in the ejection fraction of the left ventricle after ablation of the anomalous pathway.

Supraventricular tachyarrhythmia and Brugada syndrome: a case of Atrial Fibrillation and Brugada syndrome in a young patient without structural heart disease / Taquiarritmia supraventricular y síndrome de Brugada: un caso de fibrilación atrial y síndrome de Brugada en un paciente joven sin cardiopatía estructural

We report a case of a 29-year old man who initially presented with a single episode of syncope. The initial electrocardiogram (ECG) showed atrial fibrillation and an ST segment elevation on lead V1. A flecainide test unmasked the Brugada syndrome. The pathophysiology of Brugada syndrome and atrial fibrillation in this patient could be connected by sodium channel dysfunction throughout the heart. In addition, we reviewed the possible connection between Brugada syndrome and atrial fibrillation.

Reportamos el caso de un hombre de 29 años de edad que se presentó inicialmente con un solo episodio de síncope. El electrocardiograma inicial (ECG) mostró fibrilación atrial y una elevación del segmento ST en la derivación V1. Una prueba de flecainida reveló la presencia del síndrome de Brugada. La patofisiología del síndrome de Brugada y la fibrilación atrial en este paciente podrían estar conectados por una disfunción del canal de sodio a través del corazón. Además, examinamos la posible conexión entre el síndrome de Brugada y la fibrilación atrial.

Diagnóstico diferencial e tratamento das taquicardias com QRS largo / Differential diagnosis and management od wide QRS complex tachycardias

A ocorrência de taquicardias supraventriculares com complexo QRS largo no pronto-socorro é frequente e as decisões diagnósticas e terapêuticas, por vezes, têm que ser assumidas de imediato. O diagnóstico diferencial alargados e taquicardia ventricular é fundamental para o adequado tratamento. Assim, os principais aspectos do diagnóstico diferencial entre as taquicardias com complexos QRS largos são abordados, enfatizando aberrância por distúrbio da condução intraventricular como o bloqueio de ramo, as taquicardias em portadores de pré-excitação e a taquicardia ventricular. Faz-se um destaque de algumas formas de taquiarritmias, principalmente a fibrilação atrial, o flutter atrial, a taquicardia atrial ectópica e a taquicardia fascicular, sempre com a exibição eletrocardiográfica de complexos QRS largos. Finalmente, descreve-se o tratamento mais adequado no pronto-socorro, sempre com base nas evidências mais recentes, listando os agentes antiarrítmicos mais conhecidos e suas respectivas indicações e doses.

Neonatal arrhythmia with diaphragmatic eventration.

Supraventricular tachycardia is the most common symptomatic arrhythmia in young patients, frequently associated with Wolff-Parkinson-White (WPW) syndrome. We report a case of supraventricular tachycardia with Wolff-Parkinson-White (WPW) syndrome associated with partial eventration of a diaphragm in a neonate.

Incidência de choques e qualidade de vida em jovens com cardioversor-desfibrilador implantável / Incidence of shock and quality of life in young patients with implantable cardioverter-defibrillator

OBJETIVOS: Avaliar a incidência e a causa de choques de CDI em crianças e adolescentes e sua repercussão na qualidade de vida (QV). MÉTODOS: De março/1997 a fevereiro/2006, 29 pacientes (15,7±5,4 anos) foram submetidos a implante de CDI. Parada cardiorrespiratória recuperada (41,5 por cento), taquicardia ventricular sustentada (27,6 por cento) e profilaxia primária de morte súbita cardíaca (30,9 por cento) motivaram os implantes. O número de terapias foi avaliado por entrevista e pela telemetria dos CDI. A QV foi avaliada pela aplicação do questionário SF-36 e comparada à de indivíduos saudáveis. Empregou-se o método de Kaplan-Meier para análise da sobrevida livre de choques. RESULTADOS: Após 2,6±1,8 anos de seguimento, 8 (27,6 por cento) pacientes receberam 141 choques apropriados em razão de TV polimórfica (6) ou FV (2), e 11 (37,9 por cento) sofreram 152 choques inapropriados em razão de taquiarritmias supraventriculares (8) ou oversensing (3). A expectativa de sobrevida livre de choques apropriados foi de 74,2 por cento±9,0 após um ano, e de 66,7 por cento±10,7 após três anos. Observou-se diminuição da QV nos aspectos físicos (61,7±28,7), na vitalidade (64,7±19,1), na saúde mental (65,9±22,7) e nos aspectos emocionais (66,7±38,5). Medo e preocupações relacionados ao CDI foram referidos por todos os pacientes. CONCLUSÃO: A despeito da grande eficácia dessa terapêutica, a incidência elevada de choques interferiu na QV e na adaptação ao dispositivo.

OBJECTIVES: To analyze the incidence and causes of ICD therapies in children and young adults and verify their impact on the quality of life (QoL). METHODS: From March/1977 to February/2006, 29 patients (15.7±5.4 years old) were submitted to ICD implants. Aborted cardiac arrest (41.5 percent), sustained ventricular tachycardia (27.6 percent) and primary prophylaxis of sudden cardiac death (30.9 percent) indicated device therapy. The number of therapies was evaluated by interviewing patients and by ICD diagnostic data. The SF-36 questionnaire was used to measure the QoL and the results were compared to healthy population. The expectative of freedom from ICD therapies were estimated by the Kaplan-Meier method. RESULTS: After 2.6±1.8 years follow-up, 8 (27.6 percent) patients received 141 appropriate ICD shocks due to ventricular tachycardia (6) or ventricular fibrillation (2), and 11 (37.9 percent) patients received 152 inappropriate ICD shocks due to supraventricular tachyarrhythmias (8) or oversensing (3). Expectative of freedom from appropriate shocks was 74.2±9.0 percent and 66.7±10.7 percent after one and three years, respectively. Compared to healthy population, QoL decreased in physical function (61.7±28.7), vitality (64.7±19.1), mental health (65.9±22.7) and role-emotional domains (66.7±38.5). All patients referred fear and concern related to ICD use. CONCLUSION: Despite the efficacy of ICD therapies, the high incidence of appropriate and inappropriate shocks interfered in patients' QoL and adaptation to the device.

Catheter Ablation of a Left Free-Wall Accessory Pathway via the Radial Artery Approach

Catheter ablation of the left free-wall accessory pathways (APs) is normally performed by the retrograde transaortic approach via a femoral artery or the transseptal approach. Here we report a case of an overt left free-wall AP, which was successfully ablated with a retrograde transaortic approach via the radial artery without any vascular complications. The patient has remained free of any symptoms or pre-excitation observed on the ECG during a 10-month post- ablation follow-up.

Clasificación de las taquicardias auriculares / Classification of atrial tachycardias

La classificación electrocardiográfica tradicional de las taquicardias auriculares (taquicardia y flúter auricular) no refleja con precisión su mecanismo electrofisiológico. Mediante la cartografia de activación y las técnicas de encarrilamiento podemos diferenciar 2 tipos principales de taquicaria auricular: taquicardia auricular focal y macrorreentrante. Aunque la taquicardia auricular macrorreentrante más comúm es el flúter auricular típico, existen otros muchos tipos de taquicardias macrorreentrantes definidos por la localización del circuito. No hay ninguna característica del ECG, ya sea morfológica o de frecuencia que permita una separación nítida de los mecanismos subyacentes. Sin embargo es posible señalas algunas características clínicas y electrocardiográficas que se associan con frecuencia a un tipo concreto de taquicardia auricular.

Management of cardiomyopathy resulting from incessant supraventricular tachycardia in infants and children.

BACKGROUND: Radiofrequency ablation is considered to be the treatment of choice in patients with ventricular dysfunction related to incessant supraventricular tachycardia. However, reservations regarding its use in infants and children prompted us to try alternative strategies for this group. METHODS AND RESULTS: Eight children (age range: 1 day to 10 years) were diagnosed to have tachycardia-related ventricular dysfunction in the past 6 years. They presented with symptoms of palpitation, dyspnea and/or generalized swelling over the body of 3 months to 2 years'duration. The cardiothoracic ratio at presentation was 64% (52%-70%) and ejection fraction was 22.2% (15%-45%). In 7 patients tachycardia was diagnosed to be ectopic atrial and in 1 it was permanent junctional reciprocating tachycardia. Six of these children were managed with intravenous/oral amiodarone in combination with digoxin (3) and/or propranolol (2). In one child addition of amiodarone to digoxin and propranolol led to polymorphic ventricular tachycardia, and amiodarone was withdrawn. Only one child underwent radiofrequency ablation as the first choice because regular follow-up was not possible due to logistic reasons. Sinus rhythm with normalization of ventricular function was achieved in 6 of the 7 children treated medically. One child continued to have frequent episodes of tachycardia and underwent successful radiofrequency ablation of a high right atrial ectopic focus. Two out of the 6 patients on amiodarone could be managed with only digoxin and propranolol after their ventricular function had returned to normal. A third patient relapsed on stopping amiodarone and underwent successful radiofrequency ablation of a left atrial ectopic tachycardia. CONCLUSIONS: Short-term amiodarone in combination with digoxin/propranolol is a safe and effective treatment strategy for infants/children with tachycardiomyopathy. Control of tachycardia is achieved in the majority, leading to recovery of ventricular function. This approach may avoid unnecessary ablations in children or at least postpone it till the procedure would be safer.

Complicaciones transoperatorias en el implante de marcapaso endocárdico definitivo / Transoperative complications at the endocardial definitive pacemarker installation

Para determinar la frecuencia y tipo de complicaciones transoperatorias del implante del marcapaso endocárdiaco definitivo, se analizan 199 pacientes que requirieron este procedimiento. Se trató de 116 pacientes de sexo masculino y 86 del femenino, con una mediana de edad de 72 años. Treinta y seis pacientes (18 por ciento) tuvieron complicaciones transoperatorias. Las más frecuentes fueron las arritmias (25/36), entre las que predominó la taquicardia supraventricular (21/25). El resto fueron complicaciones menores como punciones arteriales que se solucionaron con compresión local. No hubo defunciones perioperatorias. Se concluye que la complicación más frecuente del implante del marcapaso endocárdiaco definitivo son las arritmias y que por lo demás la técnica es de baja morbilidad y en esta serie de nula mortalidad

Ablación con radiofrecuencia de una taquicardia por reentrada nodal atípica en una niña de 3 años / Radiofrequency catheter ablation of typical atrioventricular nodal reentrant tachycardia in a child

La presencia de una taquicardia supraventricular paroxística incesante puede llevar a una miocardiopatía dilatada secundaria, siendo ésta una de las indicaciones de ablación por radiofrecuencia. Una niña de 3 años con una taquicardia por reentrada nodal atípica complicada con miocardiopatía fue sometida a una ablación de la vía lenta, siendo el procedimiento exitoso, con recuperación rápida de la función ventricular y sin recidiva de la taquicardia

Taquicardia supraventricular fetal e hidropsia fetal näo-imunitária / Fetal Supraventricular Tachycardia and Non-immunitary Hydrops Fetalis

A case of non-immunitary hydrops fetalis, following supraventricular tachycardia, in a fetus of 29 weeks of a 28-year-old woman at the first pregnancy, who evolved with systemic hypertension and amniorrhexis, being submitted to cesarean deliver. The child needed bilateral thoracic drainage and oro-tracheal intubation for treatment of respiratory failure. Treated with digoxin and diuretic, the newborn went home at the 56th day of life. The authors emphasize the importance of the intrauterine diagnosis of the arrhythmia for the success of the treatment