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

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.

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.

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.

Successful management of persistent tachycardia using esmolol in 2 dogs with septic shock.

OBJECTIVE: To describe the successful management of 2 dogs with septic shock and persistent tachycardia using norepinephrine and esmolol, a short-acting beta receptor antagonist. SERIES SUMMARY: Two cases are reviewed. In the first case, septic shock with ventricular tachycardia was diagnosed in a 4-year-old neutered female Great Dane that underwent jejunoileal resection and anastomosis for a partial mesenteric torsion. The patient's tachyarrhythmias failed to respond to lidocaine, and an esmolol infusion was used for heart rate control. The condition of the dog improved and she was discharged after 4 days of hospitalization. The second case was a 7-year-old neutered female Cavalier King Charles Spaniel with septic peritonitis. Following surgery for intestinal resection and anastomosis, supraventricular tachycardia developed that was not responsive to volume resuscitation and was treated with an esmolol infusion. The condition of the dog improved and she was discharged after 6 days of hospitalization. Both patients were doing well at the time of long-term follow-up. NEW OR UNIQUE INFORMATION PROVIDED: This case series highlights a novel method of managing dogs in septic shock with persistent tachycardia based on recently published data in the human literature. The use of esmolol may be considered in certain veterinary patients with septic shock to improve persistent tachycardia not related to hypovolemia.

Shone's syndrome: Insights from three-dimensional echocardiography.

Shone's syndrome is a rare congenital anomaly defined as the presence of at least two of the following heart obstructions: a mitral supravalvular ring, a "parachute" mitral valve stenosis, subaortic stenosis, and aortic coarctation. A 58-year-old man presented with a mitral ring and a "parachute" mitral valve on two-dimensional transthoracic echocardiography, raising suspicion of Shone's syndrome. Three-dimensional transesophageal echocardiography revealed a subannular mitral ring inserted directly on the mitral leaflets, thus acting as a "valvar ring." This distinction can have therapeutic implications as a "valvar" mitral ring could require valve repair or replacement, instead of simple resection.

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.

An unexpected side-effect of a commonly used drug.

We report a case of a 68 year-old-female patient with clinical features of drug-induced lupus erythematosus after five years of treatment with amiodarone. She presented generalized skin rash, arthralgia on upper and lower extremities, associated with difficulty to walk. Remarkable laboratory results revealed a positive antinuclear antibody test and a skin rash biopsy showing a superficial and deep perivascular infiltrate of lymphocytes, histiocytes, and eosinophils. Once the etiology of the patient's symptoms was identified, the culprit drug was removed and she had a complete remission of all signs and symptoms. Early diagnose should be recognized for prompt intervention and avoid further complications associated with this rare side-effect.

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.

Lone atrial fibrillation in the young - perhaps not so "lone"?

OBJECTIVE: To determine if pediatric patients with a history of lone atrial fibrillation (AF) have other forms of supraventricular tachycardia (SVT) that may potentially trigger AF. STUDY DESIGN: A multicenter review of patients with lone AF who underwent electrophysiology (EP) study from 2006-2011 was performed. INCLUSION CRITERIA: age ≤21 years, normal ventricular function, structurally normal heart, history of AF, and EP study and/or ablation performed. EXCLUSION CRITERIA: congenital heart disease or cardiomyopathy. Patient demographics, findings at EP study and follow-up data were recorded. RESULTS: Eighteen patients met inclusion criteria. The mean age was 17.9 ± 2.2 years, weight was 82 ± 21 kg, body mass index was 27 ± 6, and 15 (83%) were males. Eleven (61%) were overweight or obese. Seven (39%) had inducible SVT during EP study: 5 atrioventricular nodal re-entry tachycardia (71%) and 2 concealed accessory pathways with inducible atrioventricular re-entry tachycardia (29%). All 7 patients with inducible SVT underwent radiofrequency ablation. There were no complications during EP study and/or ablation for all 18 patients. The mean follow-up was 1.7 ± 1.5 years and there were no recurrences in the 7 patients who underwent ablation. There were 2 recurrences of AF in patients with no other form of SVT during EP study. CONCLUSIONS: Inducible SVT was found in 39% of pediatric patients undergoing EP study for lone AF. EP study should be considered for pediatric patients presenting with lone AF.

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.

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.

Supraventricular tachyarrhythmia and Brugada syndrome: a case of atrial fibrillation and Brugada syndrome in a young patient without structural heart disease.

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.

Digitalis-like induced arrhythmia in a patient with rheumatic mitral regurgitation complicated by preeclampsia.

OBJECTIVE: To report a case of cardiac arrhythmia related to a low dose of endovenous lanatoside C. CASE REPORT: A 23-year-old pregnant woman with mitral regurgitation complicated with preeclampsia and pulmonary edema presented 2 episodes of atrial tachycardia induced by a intravenous digitalis (2 mg, IV and 1 mg, IV, respectively). CONCLUSION: This case calls attention to the need for further studies analysing the security of digoxin use in preeclampsia.

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.