Longitudinal Shortening of the Left Ventricle by Cine-CMR for Assessment of Diastolic Function in Patients with Aortic Valve Disease / Encurtamento Longitudinal do Ventrículo Esquerdo por Cine-RMC para Avaliação da Função Diastólica em Pacientes com Doença Valvar Aórtica

Abstract Background: Diastolic dysfunction, commonly evaluated by echocardiography, is an important early finding in many cardiomyopathies. Cardiac magnetic resonance (CMR) often requires specialized sequences that extends the test time. Recently, feature-tracking imaging has been made available, but still requires expensive software and lacks clinical validation. Objective: To assess diastolic function in patients with aortic valve disease (AVD) and compare it with normal controls by evaluating left ventricular (LV) longitudinal displacement by CMR. Methods: We compared 26 AVD patients with 19 normal controls. Diastolic function was evaluated as LV longitudinal displacement in 4-chamber view cine-CMR images using steady state free precession (SSFP) sequence during the entire cardiac cycle with temporal resolution < 50 ms. The resulting plot of atrioventricular junction (AVJ) position versus time generated variables of AVJ motion. Significance level of p < 0.05 was used. Results: Maximum longitudinal displacement (0.12 vs. 0.17 cm), maximum velocity during early diastole (MVED, 0.6 vs. 1.4s-1), slope of the best-fit line of displacement in diastasis (VDS, 0.22 vs. 0.03s-1), and VDS/MVED ratio (0.35 vs. 0.02) were significantly reduced in AVD patients compared with controls, respectively. Aortic regurgitation showed significantly worse longitudinal LV shortening compared with aortic stenosis. Higher LV mass indicated worse diastolic dysfunction. Conclusions: A simple linear measurement detected significant differences on LV diastolic function between AVD patients and controls. LV mass was the only independent predictor of diastolic dysfunction in these patients. This method can help in the evaluation of diastolic dysfunction, improving cardiomyopathy detection by CMR, without prolonging exam time or depending on expensive software.

Resumo Fundamentos: A disfunção diastólica, comumente avaliada por ecocardiografia, é um importante achado precoce na maioria das cardiomiopatias. A ressonância magnética cardíaca (RMC) frequentemente requer sequências específicas que prolongam o tempo de exame. Recentemente, métodos de imagens com monitoramento de dados (feature-tracking) foram desenvolvidos, mas ainda requerem softwares caros e carecem de validação clínica. Objetivos: Avaliar a função diastólica em pacientes com doença valvar aórtica (DVA) e compará-la a controles normais pela medida do deslocamento longitudinal do ventrículo esquerdo (VE) por RMC. Métodos: Nós comparamos 26 pacientes com DVA com 19 controles normais. A função diastólica foi avaliada como uma medida do deslocamento longitudinal do VE nas imagens de cine-RMC no plano quatro câmaras usando a sequência steady state free precession (SSFP) durante todo o ciclo cardíaco com resolução temporal < 50 ms. O gráfico resultante da posição da junção atrioventricular versus tempo gerou variáveis de movimento da junção atrioventricular. Utilizamos nível de significância de p < 0,005. Resultados: Deslocamento longitudinal máximo (0,12 vs. 0,17 cm), velocidade máxima em início de diástole (0,6 vs. 1,4s-1), velocidade máxima na diástase (0,22 vs. 0,03s-1) e a razão entre a velocidade máxima na diástase e a velocidade máxima em diástole inicial (0,35 vs. 0,02) foram significativamente menores nos pacientes com DVA em comparação aos controles normais, respectivamente. Pacientes com insuficiência aórtica apresentaram medidas de encurtamento longitudinal do VE significativamente piores em comparação aqueles com estenose aórtica. O aumento da massa ventricular esquerda indicou pior disfunção diastólica. Conclusões: Esta simples medida linear detectou diferenças significativas na função diastólica do VE entre pacientes com DVA e controles normais. A massa ventricular esquerda foi o único preditor independente de disfunção diastólica nesses pacientes. Este método pode auxiliar na avaliação da disfunção diastólica, melhorando a detecção de cardiomiopatias por RMC sem prolongar o tempo de exame ou depender de caros softwares.

Simultaneous antegrade dual AV node conduction initiates AV nodal re-entrant tachycardia [a rare initiation mechanism]

Typical atrioventricular nodal reentrant tachycardia [AVNRT] is the most common paroxysmal supraventricular tachycardia among adults. The concept of dual pathway physiology remains widely accepted, although this physiology likely results from the functional properties of anisotropic tissue within the triangle of Koch, rather than anatomically distinct tracts of conduction. AVNRT is typically induced with anterograde block over the fast pathway and conduction over the slow pathway, with subsequent retrograde conduction over the fast pathway. On rare occasions, anterograde AV node conduction occurs simultaneously through fast and slow pathways resulting in two ventricular beats in response to one atrial beat. We report a case of AVNRT where the tachycardia is always induced by the same mechanism described above. Successful ablation was achieved by slow pathway modification

Long-Term Outcome of Single-Chamber Atrial Pacing Compared with Dual-Chamber Pacing in Patients with Sinus-Node Dysfunction and Intact Atrioventricular Node Conduction

PURPOSE: The optimal pacing mode with either single chamber atrial pacemaker (AAI or AAIR) or dual chamber pacemaker (DDD or DDDR) is still not clear in sinus-node dysfunction (SND) and intact atrioventricular (AV) conduction. MATERIALS AND METHODS: Patients who were implanted with permanent pacemaker using AAI(R) (n = 73) or DDD(R) (n = 113) were compared. RESULTS: The baseline characteristics were comparable between the two groups, with a mean follow-up duration of 69 months. The incidence of death did not show statistical difference. However, the incidence of hospitalization for congestive heart failure (CHF) was significantly lower in the AAI(R) group (0%) than the DDD(R) group (8.8%, p = 0.03). Also, atrial fibrillation (AF) was found in 2.8% in the AAI(R) group, which was statistically different from 15.2% of patients in the DDD(R) group (p = 0.01). Four patients (5.5%) with AAI(R) developed AV block, and subsequently switched to DDD(R) pacing. The risk of AF was lower in the patients implanted with AAI(R) than those with DDD(R) [hazard ratio (HR), 0.84; 95% confidence interval, 0.72 to 0.97, p = 0.02]. CONCLUSION: In patients with SND and intact AV conduction, AAI(R) pacing can achieve a better clinical outcome in terms of occurrence of CHF and AF than DDD(R) pacing. These findings support AAI(R) pacing as the preferred pacing mode in patients with SND and intact AV conduction.

Discordancia atrioventricular: experiencia clínico-quirúrgica 1990-2000 / Atrioventricular discordance: then years experience

Objetivo: Conocer la frecuencia de las conexiones ventriculoarteriales combinadas con la discordancia atrioventricularial, las lesiones asociadas y los resultados quirúrgicos, incluyendo el primer caso con corrección anatómica. Material y métodos: Se analizaron todos los enfermos con discordancia atrioventricular por ecocardiografía de 1990 a marzo de 2000. Resultados: Se encontraron 36 enfermos con discordancia atrioventricular. El rango de edad 0.1 a 47 años, media 9.2. El situs atrial fue solitus en 88.9 por ciento, inversus en 11.1 por ciento. Las conexiones ventriculoarteriales fueron discordantes en 28 (77.7 por ciento); había doble vía de salida ventricular derecha en 4 (11.1 por ciento) (uno con corazón en "crisis cross"), salida única por atresia pulmonar en 4 (11.1 por ciento) y doble salida del ventrículo izquierdo en 1 (2.7 por ciento). Lesiones asociadas; comunicación interventricular con estenosis o atresia pulmonar en 21 (58 por ciento), comunicación interventricular sin obstrucción pulmonar en 10 (28 por ciento). Cinco tuvieron regurgitación tricuspídea, dos de ellos adultos. Resultados quirúrgicos: En 22 (61 por ciento) enfermos se hicieron 28 procedimientos quirúrgicos; 8 (36 por ciento) fueron paliativos y 19 (86 por ciento) correctivos, uno de éstos fue la primera corrección anatómica. La mortalidad operatoria global fue del 40.1 por ciento. Conclusiones: La disfunción ventricular derecha no es rara. Los resultados quirúrgicos revelan elevada mortalidad y la necesidad de marcapaso por bloqueo auriculoventricular posoperatorio.

Experiencia en 1.500 pacientes sometidos a ablación con radiofrecuencia en el tratamiento de las taquicardias / Treatment of tachycardias with radiofrequency ablation

Reportamos los resultados de la ablación con Radiofrecuencia (RF) en 1500 pacientes pacientes. Se realizó ablación exitosa en 5/13 (38.4 por ciento) pacientes con taquicardia auricular ectópica y en 3/7 (46 por ciento) pacientes de una taquicardia por reentrada intrauricular. Finalmente obtuvimos éxito en 28/37 (75.6 por ciento) de pacientes con taquicardia ventricular. El éxito total de la serie fue de ablación exitosa mediante radiofrecuencia en l375 pacientes (91.6 por ciento), con 142 recurrencias (9.4 por ciento) y 15 complicaciones (1 por ciento), sin mortalidadcon taquicardias, tratadas en el Instituto Nacional de Cardiología "Ignacio Chávez" desde abril de 1992 a diciembre de 1999. La taquicardia era debida a la presencia de una vía accesoria en 987 pacientes (65.8 por ciento), con un total de 1,012 vías accesorias; sólo 24 pacientes tuvieron dos o tres vías accesorias. El mecanismo de la arritmia fue reentrada intranodal (REIN) en 321 (21.4 por ciento) pacientes. Se realizó ablación del circuito de reentrada en 109 (7.2 por ciento) pacientes con flutter auricular (FLA) y, en 26 (1.7 por ciento), se realizó ablación del nodo aurículo-ventricular (A-V) por fibrilación o flutter auricular recurrente a pesar del tratamiento médico. En 13 pacientes (0.8 por ciento) se realizó ablación de una taquicardia auricular por foco ectópico (TAE), en 7 (0.4 por ciento) con taquicardia por reentrada intrauricular (TRIA) y en 37 (2.4 por ciento) se realizó ablación con radiofrecuencia de una taquicardia ventricular (TV). La ablación con radiofrecuencia fue exitosa en 908/1012 (89.7 por ciento) vías accesorias, con recurrencia en 92 casos (9 por ciento) y complicaciones en 10 (0.98 por ciento). La reentrada intranodal fue tratada con éxito en 3l9/32l pacientes con ablación selectiva de la vía lenta en 297/32l (92.5 por ciento) y de la vía rápida en 22/24 (92 por ciento). El porcentaje de complicaciones en este grupo fue de 2.4 por ciento, = 8 pacientes: 4 con bloqueo aurículo-ventricular completo (1.1 por ciento) requiriendo la implantación de marcapaso en 3. En el caso del flutter auricular, se obtuvo éxito en 86/109 pacientes (76.8 por ciento). Se realizó bloqueo AV completo por ablación de la unión aurículo-ventricular en 26/26 (100 por ciento).

Conduction disturbances in acute myocardial infarction: incidence, site-wise relationship and the influence on in-hospital prognosis.

The study was designed to assess the incidence of conduction disturbances, the relationship of the site of infarction with the type of conduction disturbances and the influence of conduction disturbances on the in-hospital prognosis. One hundred consecutive patients (M:F = 89:11) with a age range of 35-60 years with the history of first attack of acute myocardial infarction were included in the study. There were 45 anterior, 43 inferior and 12 combined anterior and inferior myocardial infarction patients. 44 of the patients had some type of conduction disturbances (Group A) and 56 had none (Group B). Inferior myocardial infarction patients showed higher incidence of conduction disturbances than anterior myocardial infarction (56.8% and 31.8% respectively) (Odd's ratio 2.98, 95% ci 1.14 to 7.9). Conduction disturbances were mostly (92%) atrio-ventricular in inferior myocardial infarction and mostly (72%) intraventricular in anterior myocardial infarction. Of the 13 cases of complete atrioventricular block, 8 had inferior, 2 anterior and 3 combined anterior and inferior infarction. In inferior infarction, complete atrioventricular block developed gradually through 1 degree and 2 degrees atrioventricular block but in the anterior infarction it developed suddenly. Patients with conduction disturbances developed more complications (84%) than those without conduction disturbances (54%). Mortality rate was higher in Group A (25%) than in Group B (3.6%) (Odd's ratio 9.0, 95% ci 1.76 to 86.73) with a overall rate of 13%. Mortality rate was higher in anterior myocardial infarction (50%) than in inferior myocardial infarction (25%) when complicated by complete atrioventricular block. It was concluded that conduction disturbances are predominantly atrioventricular in inferior and intra-ventricular in anterior MI; conduction disturbances are associated with increased risk of complications and death. Anterior location of MI may have an independent risk attribute.

Análise das características do ritmo juncional em pacientes com taquicardia por reentrada nodal submetidos a ablação da via lenta por radiofreqüência / Characteristics of Junctional Rhythm During Radiofrequency Catheter Ablation of Slow Pathway in Atrioventricular Nodal Reentrant Tachycardia

PURPOSE--To study the quantitative and qualitative aspects of junctional rhythm (JR) during radiofrequency (RF) catheter ablation of slow pathway in atrioventricular nodal reentrant tachycardia. METHODS--Twenty five patients, 5 males, ages ranging from 15 to 76 years, with recurrent atrioventricular nodal reentrant tachycardia, underwent to RF catheter ablation of slow pathway. During RF applications (40V, duration 60s) electrocardiographic was continuously recorded. The recordings were posteriorly used to study the presence and characteristics of JR (number of episodes, frequency and time of onset) at the effective and ineffective RF sessions. All variables were expressed as median and mean +/- SD. Univariate analysis of the effects of each variable on success or failure of ablation were performed using x2 test. A p value < 0.05 was considered significant. RESULTS--One hundred forty nine RF sessions were performed, 25 effective and 124 ineffective (mean per patient 6, range 1 to 22). JR was present in 18 of 25 effective and 44 of 124 ineffective sessions (p < 0.05). Mean time of appearance was 12s, occurring later this time in 9 of 18 effective and in 10 of 44 ineffective sessions (p < 0.05). Mean number of episodes was 3, occurring higher number in 7 of 18 effective and in 4 of 44 ineffective sessions (p < 0.05). Median of frequency of JR was 100bpm; 11 of 18 effective and 15 of 44 ineffective sessions presented higher frequencies (p < 0.05). CONCLUSION--JR during slow pathway ablation is a sensitive marker of ablation success. JR predictor of success has higher number of episodes, higher frequency and later time of appearance than that one of ineffective sessions.

Objetivo - Estudar quantitativa e qualitativamente as características do ritmo juncional (RJ) ocorrido durante o procedimento de ablação por cateter da via lenta, em pacientes com taquicardia por reentrada nodal. Métodos - Vinte e cinco pacientes (5 homens, 15 a 76 anos) foram submetidos a ablação por cateter da via lenta, utilizando radiofreqüência (RF). Durante as sessões de RF de 40V, com 1min de duração, foi realizado o registro eletrocardiográfico contínuo, na velocidade de 25mm/s. Os registros serviram, posteriormente, para análise da presença e das características do RJ (número de episódios, freqüência e tempo de aparecimento após o início da RF), nas sessões eficazes e ineficazes. As variáveis estudadas foram expressas em mediana, média e desvio-padrão. A análise univariada do efeito das mesmas no sucesso da ablação foi realizada, utilizando-se o teste do qui-quadrado. Valor de p<0,05 foi considerado significante. Resultados - Foram realizadas 149 sessões de RF (média de 6/paciente, variando de 1 a 22), sendo 25 eficazes e 124 ineficazes. O RJ esteve presente em 18 de 25 sessões eficazes e em 44 de 124 ineficazes (p<0,05). A média do tempo de aparecimento do RJ após o início da RF foi de 12s, aparecendo em tempo superior à média em 9 de 18 sessões eficazes e em 10 de 44 ineficazes (p<0,05). A média do número de episódios de RJ foi 3, sendo maior que a média em 7 de 18 sessões eficazes e em 4 de 44 ineficazes (p<0,05). A mediana da freqüência do RJ foi de 100bpm, sendo maior que esse valor em 11 de 18 sessões eficazes e em 15 de 44 ineficazes (p<0,05). Conclusão - O RJ durante ablação com RF é um marcador sensível do sucesso do procedimento. O RJ preditor de sucesso apresenta número maior de episódios, freqüência cardíaca mais elevada e aparece mais tardiamente durante o pulso de RF, quando comparado ao que resulta ineficaz

Mecanismos e dinâmica da progressão dos episódios de bloqueio atrioventricular 2: 1 para bloqueio atrioventricular de alto grau / Mechanisms and dynamics of episades of progression of 2:1 A-V block to high degree A-V

PURPOSE--To evaluate the mechanisms and dynamics of episodes of progression to high degree (HD) atrioventricular (AV) block (B) analyzed during incremental atrial pacing (St), in patients with previous 2:1 His-Purkinje (HP) AVB. METHODS--Data from 4 patients were analyzed. All of them with history of syncope and ECG exhibiting 2:1 AVB with wide QRS pattern. The AVB was in the HP system (HPS) in all. Every patient was submitted to electrophysiologic study with incremental atrial pacing, by which the conduction sequences and the AV conduction ratios (AVR) were analyzed. The basal (B) cycle length (CL) was defined as the shortest interval between two conducted beats (spontaneous or pacing-induced). The incremental atrial stimulation was performed beginning with CL 10 msec shorter than BCL until reaching 250 msec. RESULTS--Nineteen episodes of progression to HD-AVB were seen. A) With StCL between 31 and 26 of BCL, AVR were 3:1, 4:1 and 5:1, with only one blocking zone (BZ) in the HPS; B) with StCL between 24 and 22 of BCL, AVR were 5:1, 7:2, 9:2e11:3. In this situation a 2nd BZ ensues-on proximal, site of a decremental conduction, situated in the AV node (AVN) or in the HPS, and the other (distal level) always in HPS; C) with StCL between 24 and 16 of BCL, AVR were 5:1, 6:1, 10:2, 11:2 and 12:3. Here, these AVR were explained by postulating 3 BZ where 2 were in AVN and 1 in HPS, or inversely with 1 in AVN and 2 in HPS. The decremental conduction occurred in 1 or 2 out 3 BZ and an integral conduction (like 2:1 or 3:1) in the others. CONCLUSION--The BCL is the determinant of the AVR observed. As the StCL is shortened (< 26 BCL) a 2nd or 3rd BZ in the AVN or in the HPS ensues. These observations suggest that the mechanisms and dynamics of progression to HD-AVB apply only during incremental atrial pacing and there is a clear difference with what has been observed with the progression occurring exclusively at AV node.

Conexão átrio-fascicular com condução lenta e dissociação longitudinal. Comprovação eletrofisiológica e implicaçoes clínicas / Atrio-Fascitular Connection with Slow Conduction and Longitudinal Dissociation. Electrophysiologic Evidence ond Clinical Implications

We report on a patient with paroxysmal left bundle branch block-like tachycardia with electrophysiologic findings suggestive of nodoventricular pathway (ventricular pre-excitation dependent on slowing of AV conduction, and accessory pathway with exclusive anterograde conduction). There was no pre-excitation during sinus rhythm but it was brought on by intravenous verapamil. Atrioventricular node conduction curves showed no signs of duality. Diagnosis of an atriofascicular pathway with decremental properties was based on the following findings: 1) absence of AV dissociation during reciprocating tachycardia; 2) absence of fusion beats or narrowing QRS complexes during tachycardia; 3) advancement of right ventricular activation with late atrial extrastimuli delivered during antidromic tachycardia at a time of low right atrium refractoriness; 4) observation that earliest ventricular endocardial electrogram during tachycardia (activation mapping) was simultaneous with the right bundle potential; 5) surgical ablation of the accessory pathway by endocardial incision at the right anterior aspect of the tricuspid ring, far away from the AV node region. Evidences showing anterograde longitudinal dissociation of the accessory pathway included cycle length alternation during tachycardia and duality of accessory pathway conduction times and refractory periods. We hypothesize that reentry occurring in such AV node-like structure could give to a pre-excited tachycardia with AV dissociation mimicking antidromic tachycardia associated with nodoventricular pathway.

Resultados tardios da fulguraçäo da junçäo atrioventricular em pacientes com taquicardias supraventriculares utilizando choques de alta energia / Long Term Follow -up After Direct Current Catheter Ablation (High Energy) of the Atrioventricular Junction in Patients with Supraventricular Tachycardias

Purpose - To evaluate the long term efficacy and safety at long term after atrioventricular junction fulguration (complete AV block induction, using high energy shocks, to control drug-resistant supraventricular tachyarrythmias. Methods - Twenty-eigth patients, 17 (60,7%) men, with mean age 48,1 years, were submitted to one up to six ablation sessions with high energy shocks. The total delivered energy per patient was 1304 ± 868 J. Each shock ranged from 100 to 400J. Results - After 12 months, at least, 60,6% of patients were in complete atrioventricular block; three (10,8%) were assymptomatics without complete AV block, and infive (17,8%) the ablation was unsuccessful. Conclusion - AV junction ablation with high energy shocks is safe and efficient in long term follow-up

Objetivo - Avaliar a eficácia a longo prazo da fulguração da junção AV (indução de BAVT), utilizando choques de alta energia, para controle de arritmias supraventriculares refratárias a drogas. Métodos - Vinte e oito pacientes, 17 (60,7%) do sexo masculino, com média etária de 48,1 anos, foram submetidos a uma até seis sessões de fulquração da junção AV, com choques de alta energia. Cada paciente recebeu em média de um a dez choques. A energia total aplicada por paciente variou de 100 a 3200 J (1304 ± 868 J); cada choque foi de 100 a 400J. Resultados - No mínimo após 12 meses, 60,6% dos pacientes permaneceram em BAVT; 3 (10,8%) pacientes apresentam-se assintomáticos, com alterações na condução AV, sem apresentar BAVT. Em 5 (17,8%) pacientes o procedimento foi ineficaz. Conclusão - A fulguração da junção AV (indução de BA VT) com choques de alta energia é procedimento seguro e eficaz a longo prazo

Taquicardiomiopatia induzida por fibrilaçäo atrial / Atrial fibrillation-induced tachycardiomyopathy

Mulher de 56 anos, com coraçäo anatomicamente normal, desenvolveu dilataçäo e hipocontratilidade difusa importantes do VE após algumas semanas em fibrilaçäo atrial refratária de alta resposta ventricular. Reduçäo da freqüência cardíaca com verapamil resultou em rápida normalizaçäo da contratilidade miocárdica

A 56 year old woman with a previously normal heart developed severe left ventricular dilation and hypocontratility after a few weeks of a refractory, high ventricular rate atrialfibrillation. Reduction of heart rate with verapamil resulted in a rapid normalization of myocardial contractility

Electrocardiographic features of atrial depolarization during pacing of right atrial appendage.

Identification of atrial capture during pacing from right atrial appendage is frequently difficult. Electrocardiograms of forty five patients implanted with AAI/DDD pacemakers (thirty unipolar, fifteen bipolar) were analysed to characterize the specific morphology of paced P waves. Compared to sinus P waves, atrial pacing resulted in atrial depolarization of lower amplitude (0.16 +/- 0.05 mv vs 0.11 +/- 0.032 mv, P less than 0.005) but increased duration (0.07 +/- 0.009 sec vs 0.08 +/- 0.017 sec, P less than 0.005). P wave morphology was similar in unipolar and bipolar pacing units. It was positive in lead I (80%), II (71.11%), III (80%) and aVF (75.55%). In lead aVL, paced P waves were usually diphasic with an initial negative deflection (35.55%). Precordial leads showed paced atrial depolarization of small amplitude and did not help in identification of atrial capture. In unipolar pacing P waves were best seen in lead III because of small pacing spike in this lead. Lead II was suitable for identification of paced P waves in bipolar pacing. Thus careful examination of standard ECG leads for paced P waves of low amplitude, prolonged duration and specific morphology can help in confirming atrial capture following pacing stimulus from right atrial appendage.

Nova técnica para tratamento da taquicardia por reentrada nodal: desconexäo posterior do nó atrioventricular / New technique for the treatment of nodal reentry tachycardia: dissection of the posterior part of atrioventricular node

No período de março de 1987 a novembro de 1989, 20 pacientes com idade variável entre 20 e 74 anos, 13 do sexo feminino, portadores de taquicardias por reentrada nodal (TRN) recorrentes e refratárias a terapêutica medicamentosa, foram submetidos atratamento cirúrgico. O estudo eietrofisiológico pré-operatório demonstrou intervalo VA durante TRN menor que 40 ms e a despolarizaçao atrial retrógrada se iniciava na porçao anterior ao nó AV. O mapeamento intra-operatório feito durante estimulaçao ventricular mostrou desplarizaçao atrial retrógrada posterior ao nó AV. Independentemente do local mais precoce de ativaçao atrial, anterior ou posterior ao nó AV, em todos os casos a abordagem foi posterior, sendo realizada a desconexao posterior do nó AV. Após cardioplegia, a incisao foi realizada no átrio direito, a 2 mm do anel tricúspide, e paralela ao mesmo, iniciando-a a 2 mm atrás do feixe de His, previamente localizado. A extensao posterior da incisao ultrapassou em 2 cm o óstio do seio coronário. Através dessa incisao, toda a regiao correspondente ao limite posterior do nó AV foi separada das estruturas vizinhas, seio coronário, parede atrial direita, porçao póstero-superior do ventrícuio esquerdo, septo interventricular e porçao subanular do ventrículo direito. Em profundidade, a dissecçao atingiu a parede do átrio esquerdo, na sua junçao com o anel correspondente. Todos os pacientes sobreviveram à intervençao e encontram-se assintomáticos. Antes da alta hospitalar, o teste eletrofisiológico pós-operatório realizado com estimulaçao atrial epicárdica e com l e 2 extra-estímulos, durante ritmo sinusal, em 600 e 400 ms e após bloqueio parasimpático completo com atropina O,01 mg/kg, nao induziu nenhuma forma de taquicardia nodal. A técnica proposta é simples e curativa; o mapeamento intra-operatório torna-se dispensável; as conexoes posteriores do nó AV sao indispensáveis no circuito de reentrada; a funçao do nó AV, o intervalo PR e a freqüência de Wenckeback nao se alteram no pós-operatório.