Inducción de taquicardia reentrante nodal aurículo-ventricular por aplicación de radiofrecuencia / Induction of atrioventricular nodal reentrant tachycardia by radiofrequency application

La taquicardia reentrante nodal aurículo ventricular es la forma más común de taquicardia sostenida, regular con QRS angostos. Fisiopatológicamente está determinada por una anatomía y fisiología nodal aurículo ventricular dual, con una vía rápida y otra lenta que forman el sustrato de la reentrada. El estudio electrofisiológico determina el diagnóstico de certeza si es inducida, aunque en algunos casos no es posible. Presentamos nuestra casuística donde la aplicación de radiofrecuencia indujo taquicardia reentrante nodal aurículo ventricular cuando el estudio electrofisiológico no pudo hacerlo, y explicamos su mecanismo electrofisiológico.

Atrioventricular nodal reentrant tachycardia is the most common form of sustained regular narrow QRS complex tachycardia. It is caused by the presence of a dual atrioventricular nodal anatomy and physiology, with a fast and a slow pathway forming a substrate for re-entry. Electrophysiology study confirms the diagnosis when the tachycardia is induced, although in some cases this is not possible. Casuistry is here presented where the application of radiofrequency induced atrioventricular nodal reentrant tachycardia, when the electrophysiological study could not do it; we explain here its electrophysiological mechanism.

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.

Necesidad de estimulación ventricular rápida en la inducción de taquicardia por reentrada del nodo aurículo-ventricular: Caso clínico / Requirement of fast ventricular stimulation to induce atrio ventricular nodal tachycardia: Report of one case

We report a 59 year-old woman who had recurrent episodes of paroxystic supraventricular tachycardia despite pharmacologic therapy. A previous electrophysiological study (EPS) was done two years earlier without induction of any sustained arrhythmia. A new EPS was performed, during which atrial and ventricular programmed stimulation failed to induce tachycardia, and only by fast ventricular stimulation during intravenous isoproterenol infusion, a typical atrio ventricular nodal reentrant tachycardia (AVNRT) was induced. We successfully ablated the slow nodal pathway. After ablation the tachycardia was not inducible. We comment the occasional difficulties to induce AVNRT and the importance of a complete induction protocol to avoid false negative studies during the EPS.

A segurança e a eficácia da ablação da taquicardia reentrante nodal em uma grande série de casos / Safety and efficacy of atrioventricular nodal reentrant tachycardia ablation in a large group of patients

Objetivo: Analisar os resultados e as complicações em uma série de casos de ablação por radiofreqüência de taquicardia atrioventricular reentrante nodal (TAVN). Métodos: Foram estudados, retrospectivamente, 1428 pacientes submetidos à ablação por radiofreqüência do circuito da TAVN. Todos os pacientes apresentavam taquicardia clínica sintomática repetitiva e indução sustentada ou não-sustentada de TAVN no estudo eletrofisiológico. O procedimento utilizou o mapeamento anatômico do triângulo de Koch com aplicações de radiofreqüência controladas por temperatura (máximo 60 graus centígrados), objetivando a modificação ou a ablação da via lenta. Os pacientes foram revistos entre 15 e 90 dias após o procedimento. Resultados: A idade média da população estudada foi de 50 maior ou menor que 8 anos, sendo o sexo feminino o mais prevalente (76,2 por cento). A não-indução da arritmia, após a ablação por radiofreqüência, ocorreu em 98,89 por cento dos pacientes. Houve recorrência precoce em 1,75 por cento dos pacientes. As complicações irreversíveis observadas foram: bloqueio atrioventricular total, observado em 3 pacientes (0,21 por cento); pseudo-aneurisma de femoral necessitando de cirurgia em 1 paciente (0,07 por cento). A eficácia final, considerando-se apenas os casos curados sem complicações irreversíveis, foi de 96,85 por cento. Dois outros pacientes apresentaram tamponamento agudo na sala de exame, com imediata drenagem e recuperação. Conclusões: A ablação por radiofreqüência da TAVN nodal apresenta alta eficácia e baixíssima incidência de complicações.

All that glitters is not gold ... all that faints is not slow.

An 82 year old man presented with multiple syncopal episodes. Since his ECG showed LBBB (left bundle branch block) with first degree AV block, he was advised permanent pacemaker implantation. However, a wide QRS tachycardia on the Holter raised the possibility of tachycardia-mediated syncope. EP (electrophysiological) studies revealed easily and repeatedly inducible short lasting slow-fast AVNRT (atrioventricular nodal reentry tachycardia) with severe hypotension. After RF ablation of the slow pathway, he is asymptomatic at six month follow-up.

Cardiomiopatia mitocôndrica hipertrófica associada à síndrome de Wolff-Parkinson-White / Mitochondrial hypertrophic cardiomyopathy associated with Wolff-Parkinson-White syndrome

Atualmente, diversas doenças cardíacas são reconhecidas como de origem genética. As mutações em genes, que codificam várias proteínas do sarcômero com desarranjo miofibrilar e dos miócitos, e a mutação associada à síndrome de Wolff-Parkinson-White, identificada no cromossomo 7q3 como resultado de uma mutação pontual no gene, que codifica uma subunidade reguladora de AMP - proteína quinase ativada, expressa em hipertrofia ventricular, pré-excitação ventricular ou ambas, são dois exemplos de cardiomiopatia hipertrófica familiar 1-3. Outras doenças cardíacas congênitas, nas quais a cardiomiopatia hipertrófica ou dilatada e distúrbios elétricos, podem estar presentes em cerca de 20 a 30 por cento de pacientes, incluem algumas doenças mitocondriais4-6. Apresentamos um caso de uma recém nascida com taquicardia persistente secundaria à síndrome de Wolf-Parkinson-White, na qual hipertrofia importante e outras anormalidades sistêmicas foram atribuídas à doença mitocondrial.

Taquicardias con complejo QRS ancho: ¿Cómo establecer la diferencia?: parte I / Tachycardia with a wide QRS complex: part I

Las taquicardias con complejos QRS ancho revierten un valor pronóstico y terapéutico de gran importancia en la práctica clínica cotidiana. Se han descripto una cantidad importante de criterios que ayudan al diagnóstico diferencial de las mismas. Se considera oportuno describir la frecuencia de aparición, mecanismos, algoritmos, el aporte de drogas y estudios complementarios para establecer un diagnóstico apropiado

Taquicardias ortodrómicas e intranodales: equívocos diagnósticos y ablación / Orthodromic and intra-nodal tachycardia. Diagnostic mistakes and ablation

Resulta trascendente el diagnóstico diferencial entre las taquicardias ortodrómica e intranodal, por su frecuencia, la orientación del estudio electrofisiológico y la terapéutica antiarrítmica o ablativa que se debe emplear. Los conocimientos electrofisiológicos llevados al electrocardiograma ofrecen criterios orientadores, pero ciertos casos se apartan de los modelos. El objetivo fue precisar la frecuencia del hecho y las variantes de cada taquicardia. Se estudiaron 40 pacientes entre 14 y 78 años, en un período de 14 meses. Se documentó la taquicardia con un diagnóstico presuntivo; la estimulación eléctrica programada precisó el definitivo, con posterior ablación: intranodales (29), ortodrómicas (10), ambas (1). Hubo congruencia clínico-electrofisiológica en 30 (75); en 10 existió error o duda: intranodales (6), ortodrómicas (3), ambas (1). Las variedades de la intranodal son: P superpuesta al QRS, como fuerza terminal, RP menor de 60 ms, RP mayor o igual a 60 ms, RP mayor que el PR, P delante del QRS; y las de la ortodrómica: RP mayor o igual a 60 ms, RP menor que 60 ms, y RP mayor que el PR. Se concluye que el diagnóstico puede establecerse por el electrocardiograma pero existen variantes que llevan a equívocos diagnósticos, que aclarará el estudio electrofisiológico

Taquicardia ventricular por reentrada de rama a rama: presentación de tres casos / Ventricular tachycardia due to reentry within the bundle branches: report of three cases

Ventricular tachycardia due to reentry within the bundle branches occurs in the presence of left ventricular dilatation and conduction alterations in the His-Purkinje system. A macro-reentry is formed by the His bundle, left and right bundles and ventricular myocardium. The anatomical substrate of this arrhythmia is ventricular dilatation. However, it may appear in healthy hearts. Alterations of intraventricular conduction are reflected by a prolongation of PR intenval and bundle branch block in the surface EKG and prolongation of HV interval in the endocavitary registry. During tachycardia, His activation precedes ventricular activation. We report three patients aged 55,58 and 78 years old with a dilated cardiomyopathy and ventricular tachycardia due to reentry within the bundle branches. All had a left bundle branch block and a prolonged HV internal. The arrhythmia was induced during the study in two patients. All were subjected to radiofrequency fulguration of the right branch of the His bundle. After fulguration, two remained with a pattern of complete right bundle branch block and one with a complete intermittent AV block. All three are free of arrhythmic events

Ablación por catéter con radiofrecuencia en la taquicardia por reentrada nodal en pacientes con PR largo: reporte de un caso / Radiofrequency catheter ablation for nodal reentry tachycardia in patients with long PR

La taquicardia por reentrada nodal es la más común de las taquicardias supraventriculares y su tratamiento de elección es la ablación por catéter con radiofrecuencia. Esta se dirige habitualmente a eliminar la vía nodal lenta, procedimiento igualmente eficaz pero considerado más seguro que la ablación de la vía rápida. Existen situaciones clínicas sin embargo, donde puede existir indicación de realizar la ablación de la vía rápida. Presentamos el caso de un paciente con intervalo PR prolongado y con taquicardia supraventricular por reentrada nodal prácticamente incesante en el cual se realizó mapeo y ablación de la vía rápida

Analysis of local electrograms at successful and unsuccessful sites for slow pathway ablation of atrioventricular nodal reentrant tachycardia.

Anatomic and electrogram approaches have been described for ablation of slow pathway in patients with atrioventricular nodal tachycardia. The purpose of this study was to identify parameters to predict successful slow pathway ablation using the anatomic approach. Local electrograms at successful and unsuccessful sites were compared in 36 patients undergoing slow pathway ablation using anatomic approach. A total of 208 local electrograms were studied. Fragmented atrial electrogram was seen in 24/36 (67%) of successful and in 46/172 (26%) of unsuccessful sites (p < 0.001). The sensitivity, specificity and positive and negative predictive values of fragmented atrial electrogram were 67, 73, 34 and 91 percent respectively. A slow pathway potential was noted in three of successful sites. There was no difference in the atrial to ventricular amplitude ratio in these sites. In conclusion, fragmentation of atrial electrogram and presence of possible slow pathway potential are seen more often at successful than at unsuccessful sites. In our opinion, while using an anatomic approach for slow pathway ablation, an analysis of local electrogram may help in identifying the proper site and avoiding unnecessary radiofrequency energy delivery.

In-hospital results of radiofrequency ablation of supraventricular tachycardia.

Two hundred and one consecutive patients with symptomatic paroxysmal supraventricular tachycardia (PSVT) underwent a diagnostic electrophysiological test and catheter ablation with radiofrequency (RF) current. In 102 (51%) patients, the mechanism of PSVT was found to be atrioventricular nodal reentry (AVNRT, typical in 101, atypical in 1). Atrioventricular reentrant tachycardia (AVRT) involving accessory pathway was present in 94 (47%) and ectopic atrial tachycardia in 5 patients. A successful outcome was achieved in 100 of 102 patients (98%) with AVNRT and in 85 of 94 patients (90%) with AVRT. The anatomical approach was used for ablation in patients with AVNRT. The focus was ablated in 4 patients with ectopic atrial tachycardia whereas it was modified in the remaining one patient. Procedure-related complications occurred in 4 patients (2 AVNRT, 2 AVRT). One patient each developed haemothorax, pericardial effusion, mitral valve endocarditis and high-grade AV block requiring permanent pacemaker implantation. The electrode and ablation catheters were repeatedly used after ethylene oxide sterilisation to reduce the cost of the procedure. RF ablation is an effective, safe and curative modality of treatment for patients with symptomatic PSVT due to AVNRT and AVRT. The experience with this modality in patients with ectopic atrial tachycardia is limited.

Tratamento cirúrgico da taquicardia por reentrada nodal: resultados tardios / Long-term Results of Surgical Treatment of Atrioventricular Nodol Reentrant Tachycardia

Métodos - No período de março de 1987 a março de 1990, 20 portadores de TRN foram submetidos a tratamento cirúrgico, 14 do sexo feminino, com idades variando entre 12 e 70 (média 42,8 ± 17,1) anos. Apresentavam crises recorrentes de TRN de 6 meses a 60 anos (média de 18,4 15,9 anos ). Dez apresentaram síncopes ou présíncopes durante as crises e dois foram ressuscitados durante tentativa de reversão com drogas antiarrítmicas. Fizeram uso de 1 a 6 (média de 3,75 ± 1,45) drogas antiarrítmicas, sem sucesso. Todos foram submetidos a estudo eletrofisiológico que caracterizou a forma comum de TRN. O procedimento cirúrgico foi semelhante em todos os casos, com dissecção profunda da região perinodal posterior. Seis pacientes submeteram-se a procedimentos cirúrgicos associados. Dezoito pacientes foram submetidos a estimulação atrial programada antes da alta hospitalar. A avaliação tardia resultou de observação clínica ambulatorial e de EEF e Holter quando necessários. Resultados - A estimulação atrial programada realizada em 18 pacientes não reproduziu a TRN, mesmo após administração de atropina IV. A média do intervalo PR variou de 153 ± 50,36 ms no pré, para 152 ± 38 ms no pós-operatório (p>0,05). Nenhum paciente apresentou recorrência da TRN no seguimento de 26,3 ± 10 m. Dois pacientes evoluíram para FA crônica após 24 meses da cirurgia. Conclusão - A técnica de dissecção perinodal empregada foi eficaz e segura a longo prazo, preservando a condução AV

Purpose - To analyze the long term results of surgical treatment of atrioventricular nodal reentrant tachycardia (AVNT). Methods - From March 1987 to March 1990, 20 patients with AVNT were submitted to surgical therapy, 14 female, aged 12 to 70 (42.8 ± 17) years. All presented crisis of AVNT from 6 months to 60 (18.4 ± 15.9) years. Ten of them had syncope or near syncope and two with cardiac arrest during reversion of AVNT with antiarrythmic drugs. They used 1 to 6 (3.75 ± 1.45) antiarrythmic drays before surgery. The electrophysiologic study (EPS) showed the commom form of AVNT in all cases. The surgical procedure was anatomically directed to the posterior area of the AV node. Programmed atrial stimulation (PAS) were applied on 18 patients after surgery. The longterm results were analysed by clinical evaluation, EPS andHolter when they were necessary. Results - The pos-operative PAS was done in 18 patients and did not induce any AVNT, even after atropine IV. The PR interval was 153 ± 50 ms before and 152 ± 38 ms after surgery (p > 0.05). During follow up (26 ± 10 m) there were not AVNT reccurence. Two patients developed chronic atrial fibrillation after 24 months of surgery. Conclusion - The perinodal dissection technique used was safe and successful to treat AVNT, preserving AV nodal conduction

Reciprocal beats of atrial origin terminating atrioventricular nodal wenckebach periods with atrioventricular reentrant tachycardia in the Wollf Parkison White Syndrome

A Patient with the Wolf-Parkinson-White syndrome demonstrating reciprocal beat of atrial origin aborting atrioventricular nodal Wenckebach periods, and atrioventricular bypass reentrant tachycardia, is presented