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.

Recording of double atrial potentials as a marker for isthmus block during ablation of atrial flutter.

Radiofrequency ablation is an established method for treatment of type I atrial flutter. The assessment of creation of complete bidirectional isthmus block following linear ablation of the isthmus is an integral part of ablation procedure. Conventionally, bidirectional isthmus block is tested by pacing on either side of ablation line and looking for reversal of activation sequence in the right atrium. We looked at the feasibility of recording double potentials, separated by an isoelectric interval along the ablation line as an alternative method to demonstrate bidirectional isthmus block. An attempt was made to record the double potentials following linear ablation of the cavotricuspid isthmus. Following ablation, bidirectional isthmus block was also tested by pacing from the coronary sinus os and the low-lateral right atrium. We could demonstrate double potentials in 9 of the 11 patients in whom we attempted to record them following linear ablation of flutter. The presence of bidirectional block by pacing from coronary sinus os and low lateral right atrium could be demonstrated in 10 (91%) patients. Thus, double atrial potentials, separated by an isoelectric interval can be demonstrated following ablation of atrial flutter. Double potentials, if demonstrable on coronary sinus os and low lateral right atrium pacing, could serve as an alternative marker of isthmus block.

Quemaduras eléctricas en niños: reporte de tres casos relacionados con papalotes. Revisión de la literatura / Electric burns in children: report of three cases related with kites and a rewiew of the literature

Introducción: de todas las quemaduras las eléctricas constituyen una fracción pequeña pero devastadora.Presentación de los casos: se muestra la experiencia con tres niños que sufrieron quemaduras eléctricas asociadas a la práctica recreativa de volar un papalote (volantín, culebrina o cometa). Dos fueron masculinos (9 y 10 años) y un femenino (10 años). Los mecanismos de lesión fueron al intentar bajar el papalote de los cables en que se enredó y al tocar cables de alta tensión con hilo metalizado y con hilo de cobre. Dos casos sufrieron además lesiones por caída. Un paciente presentó un bloqueo transitorio de rama derecha del haz de His y otro requirió amputaciones múltiples e injerto autólogo. El periodo de hospitalización fue de 5 a 34 días, ninguno de los pacientes presentó insuficiencia renal aguda y no hubo defunciones. Conclusiones: se deben desarrollar programas preventivos para disminuir el número de quemaduras eléctricas relacionadas con papalotes y sus secuelas invalidantes.

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.

Ablación por radiofrecuencia de haces auriculoventriculares anómalos en niños con taquicardia paroxística supraventricular / Radiofrequency ablation of abnormal atrioventricular bundle in children with paroxysmal supraventricular tachycardia

En 21 pacientes (edad promedio 9,7, márgenes 4 a 16 años) con taquicardias paroxísticas supraventriculares por haces paraespecíficos, se realizaron estudios eslectrofisiológicos y ablación de los haces por radiofrecuencia. Dos pacientes tenían malformaciones congénitas del corazón. La ablación se consiguió en 12/15 haces anómalos izquierdos (80 por ciento) y en 4/6 derechos (67 por ciento), en 10/12 pacientes con preexitación (83//) y 6/9 haces ocultos (67 por ciento) (diferencias no significativas). El buen éxito se obtuvo en 76 por ciento (16/21) del total de pacientes, pero éste aumentó a 84 por ciento (p=0,048 Fisher) después de eliminar los pacientes con malformaciones congénitas. Las complicaciones observadas incluyeron obstrución arterial con síndrome de compartimiento y perforación con taponamiento (un caso de cada una). La ablación por radiofrecuencia es un tratamiento adecuado y definitivo en niños con taquicardia paroxística supraventricular,independientemente de la localización de la vía anómala y la presencia de preexitación, pero puede fracasar en casos de malformaciones cardíacas. Las complicaciones de importancia son poco frecuentes, pero pueden llegar a ser graves, lo que exige una rigurosa selección de los pacientes a estudiar

Trastornos de conducción a niveles múltiples durante la fase aguda del infarto del miocardio: estudio electrofisiológico / Multiple block sites during the acute phase of myocardialinfarction diagnosed by His bundle electrogram

Estudiamos 40 pacientes con infarto del miocardio (24 de la cara anterior y 16 de la inferior) en evolución, (IME): 37.5 por ciento con bloqueo AV de segundo y tercer graso, 30 por ciento con bloqueos de la rama derecha y de la subdivisión anterior izquierda, 12.5 por ciento con bloqueos de rama derecha y de l asubdivisión posterior izquierda y 20 por ciento con bloqueo troncular de la rama izquierda. Con el fin de precisar el nivel anatómico del bloqueo, a los enfermos se les practicó estudio electrofisiológico. En los pacientes con infarto del miocardio inferior y bloqueo AV, se encontró buena correlación entre el electrocardiograma y el electrograma de His, localizando el trastorno de conducción a nivel del nod AV (suprahisiano). En cambio en los pacientes con IME anteroseptal, en los que el ECG sólo mostraba bloqueo de rama troncular o en alguno de los fascículos distales, el electrograma de His registró bloqueos en múltiples niveles: el 70 por ciento con bloqueos a nivel intra e infrahisianos, que evolucionaron súbitamente hacia bloqueos AV avanzados. Puede ser que el mecanismo de estos bloqueos sea la disociación funcional longitudinal en la conducción, debida más a una lesión isquémica del tronco del haz de His, que a un bloqueo súbito y simultáneo de todos sus fascículos. Concluimos que el estudio eletrofisiológico es un procedimiento de gran utilidad para identificar a los pacientes con múltiples trastornos de conducción, cuyo pronóstico es menor favorable que para aquellos pacientes que sólo presentaron bloqueos suplrahisianos

Significado por intervalo PR prolongado em pacientes com bloqueio dos ramos do feixe de his do tipo bifascicular / Significance of prolonged PR interval in patients with bundle of his branch block type bifascicular

Purpose­Evaluation of the prolonged PR interval and its predictive value for trifascicular block in individuals with bifascicular His bundle branch block. Patients and Methods­55 patients, 36 male and 19 female aged 57 + 15,8 years with bifascicular bundle branch block type have been studied. 11 cases had complete left bundle branch block and 44 cases had complete right bundle branch block with left anterior ana superior division block. His bundle electrogram and atrial stimulation were performed in all patients. The atrial stimulation rate originating the Wenckebach phenomenon (SP) of the A-V conduction, and the A-H and H-V intervals were compared with the PR interval of the surface electrocardiogram. Patients were divided into three groups according to the PR interval: group 1, Pr < 200 ms, group II, PR between 190-280 ms and group III,PR 280 ms. Results­There was not linear correlation between the PR interval and WP in the three groups. There was a weak linear ascending correlation between the PR and A-H intervals in groups I and II (r + 0.59 and + + 0.43, respectively) and there was a descending correlation in the group III (r. - 0.64, P < 0.05). In relation to the H-V interval there was not linear correlation with the PR interval in groups I and II, but there was a good ascending linear correlation in the group III (r 0.84, P < 0.01). The incidence of prolonged A-H and H-V intervals increased as the PR interval was larger. Conclusion­ The prolonged PR interval with bifascicular bundle branch block means, in the majority of cases, diffuse damage of the conduction system envolving the A-V node and the infranodal region; starting from 280 ms, the delayed PR interval suggests envolvement predominantly below the A-V node: to a higher PR interval corresponds a higher H-V interval and also, to a relatively shortest A-H interval

Bloqueios de ramos intermitentes e transitórios / Intermittent and transient bundle-branch block

Säo estudados 17 casos de bloqueios intermitentes e transitórios de ramo, denominados fase-3 (taquicardia-dependentes), fase-4 (bradicardia-dependentes ou paradoxais) e näo-freqüência-dependentes, de acordo com a refratariedade das fibras de Purkinje do ramo e com o momento do estímulo no ciclo cardiaco. E estabelecida uma classificaçäo clínica de acordo com as diversas modalidades de bloqueios encontrados