Silvia Helena Cardoso Boghossian

Electrical behavior of T-wave polarity alternans in patients with congenital long QT syndrome.

OBJECTIVESnThis study was designed to evaluate the incidence and characteristics of onset of T-wave polarity alternans (TWPA) in patients with long QT syndrome.nnnBACKGROUNDnThe T-wave alternans is a phenomenon that consists of beat-to-beat variability in the amplitude, morphology, and sometimes polarity of the T-wave, and it may trigger life-threatening arrhythmias.nnnMETHODSnThe 24-h Holter recordings of 11 patients with congenital long QT syndrome were studied. Episodes of TWPA with 10 or more consecutive cycles were selected and analyzed as follows: 1) mean cycle length (MCL) and QTc interval duration (QTcI) of the episodes of TWPA and the 10 cycles preceding and succeeding the TWPA; 2) MCL and QTcI of the third, second, and first minute before onset (Mn_3, Mn_2, Mn_1); 3) MCL and QTcI from the tenth to the first cycle immediately preceding the onset of TWPA (R_10 to R_1); 4) MCL and QTcI from the first to the fourteenth cycle during alternans (R0 to R14); 5) MCL and QTcI from the first to the tenth cycle immediately succeeding TWPA (R+1 to R+10); 6) linear correlation (Lnc) between QT interval and cycle length (CL) (LncQT/CL) during alternans and for the 10 preceding cycles; 7) Lnc between the first three alternans cycles and episode duration (Lnc 3CL/EpD); and 8) difference between the longest and shortest QTc interval. We also selected episodes consisting of four or more consecutive cycles in order to analyze daily rhythms of the phenomenon.nnnRESULTSnThe TWPA was observed in 5 (45%) out of the 11 patients studied. The alternans process is initiated by a sudden shortening of the first alternans cycle without previous heart rate changes and ends at the moment when prolongation of the cycle tends to occur. LncQT/ CL-alternans: r = 0.38 +/- 0.2 (p = 0.20); without alternans: r = 0.81 +/- 0.06 (p = 0.01). Lnc 3CL/EpD: r = 0.002 (p = 0.992). The QTc difference during alternans: 312.0 +/- 52.1 ms; without alternans: 86.0 +/- 36.4 ms (p = 0.001). Daily rhythm: 71% of the episodes occurred between 8 AM and 8 PM, with higher incidence during the morning.nnnCONCLUSIONSnThe TWPA was dependent on the cardiac CL; there was loss of the LncQT/CL and an increase in the QT interval variability. Like other biological variables, T-wave polarity alternans has a higher density during the morning.

Signal-averaged P wave in patients with wolff-parkinson-white syndrome after successful radiofrequency catheter ablation

OBJECTIVESnWe attempted to establish a relation between the atrial conduction time assessed by the signal-averaged P wave electrocardiogram and episodes of paroxysmal atrial fibrillation in patients with the Wolff-Parkinson-White syndrome.nnnBACKGROUNDnThe incidence of paroxysmal atrial fibrillation is higher in patients with the Wolff-Parkinson-White syndrome than in normal persons. However, the role of intraatrial conduction delay in precipitating the disorganization of atrial rhythm is not completely understood.nnnMETHODSnThe total duration of the signal-averaged P wave and the P wave in standard lead II was evaluated after successful radiofrequency catheter ablation in 28 patients with the Wolff-Parkinson-White syndrome. The data obtained from 17 patients (61%) with a documented history of prior paroxysmal atrial fibrillation (group I) were compared with those obtained from 11 patients (39%) without a history of atrial fibrillation (group 2). Both groups were further compared with a normal control population.nnnRESULTSnThe mean +/- SD signal-averaged P wave duration in group 1 was 141.94 +/- 9.47 ms (range 130.0 to 171.0). Fourteen patients (82%) in this group showed a P wave duration > 135.0 ms. In group 2, the signal-averaged P wave duration was 126.64 +/- 8.72 ms (range 111.0 to 136.0). Only one patient in this group (9%) showed a P wave duration > 135.0 ms (p < 0.000, group 1 vs. group 2). The signal-averaged P wave duration in the control group was 124.46 +/- 4.49 ms (range 115.0 to 129.5; p < 0.000, group 1 vs. the control group; p < 0.454, group 2 vs. the control group). The P wave duration in lead II was 92.06 +/- 8.85 ms in group 1 and 92.27 +/- 7.86 ms in group 2 (p < 0.949). Using a cutoff value of < 135.0 ms for a normal signal-averaged P wave duration, the method had a sensitivity and specificity and positive and negative predictive values of 82%, 91%, 93% and 77%, respectively, for identifying patients with clinical paroxysmal atrial fibrillation.nnnCONCLUSIONSnIn the current study, the signal-averaged P wave showed a prolonged intraatrial conduction time in patients with the Wolff-Parkinson-White syndrome and paroxysmal atrial fibrillation. These patients can be differentiated from those with the pre-excitation syndrome without clinical atrial fibrillation as well as from normal subjects. The prolonged intraatrial conduction time may serve as an atrial substratum for development and maintenance of the fibrillatory state.

Arrhythmogenic cardiomyopathy of the right ventricle. Predictive value of QT interval dispersion to assess arrhythmogenic risk and sudden death

OBJECTIVEnTo determine in arrhythmogenic right ventricular cardiomyopathy the value of QT interval dispersion for identifying the induction of sustained ventricular tachycardia in the electrophysiological study or the risk of sudden cardiac death.nnnMETHODSnWe assessed QT interval dispersion in the 12-lead electrocardiogram of 26 patients with arrhythmogenic right ventricular cardiomyopathy. We analyzed its association with sustained ventricular tachycardia and sudden cardiac death, and in 16 controls similar in age and sex.nnnRESULTSn(mean +/- SD). QT interval dispersion: patients = 53.8+/-14.1 ms; control group = 35.0+/-10.6 ms, p = 0.001. Patients with induction of ventricular tachycardia: 52.5+/-13.8 ms; without induction of ventricular tachycardia: 57.5+/-12.8 ms, p =0.420. In a mean follow-up period of 41+/-11 months, five sudden cardiac deaths occurred. QT interval dispersion in this group was 62.0+/-17.8, and in the others it was 51.9+/-12.8 ms, p = 0.852. Using a cutoff > or =60 ms to define an increase in the degree of the QT interval dispersion, we were able to identify patients at risk of sudden cardiac death with a sensitivity of 60%, a specificity of 57%, and positive and negative predictive values of 25% and 85%, respectively.nnnCONCLUSIONnPatients with arrhythmogenic right ventricular cardiomyopathy have a significant increase in the degree of QT interval dispersion when compared with the healthy population. However it, did not identify patients with induction of ventricular tachycardia in the electrophysiological study, showing a very low predictive value for defining the risk of sudden cardiac death in the population studied.

The Frequency Analysis of Signal‐Averaged ECG of P Wave as Predictor of Efficacy of Class III Antiarrhythmic Drugs to Maintain Sinus Rhythm in Recurrent Idiopathic Atrial Fibrillation

Background: The use of class III antiarrhythmic drugs (ADIII) has been considered a good predictor of sinus rhythm in patients post‐cardioversion from atrial fibrillation (AF). Several studies using frequency domain analysis of signal‐averaged ECG (FDSAECG) of the P wave were able to identify patients at risk for AF. The aim of this study was to assess the FDSAECG in predicting recurrence of idiopathic persistent AF (IPAF) in patients under ADIII therapy.

Reversal atrial electrical remodeling following cardioversion of long-standing lone atrial fibrillation

FUNDAMENTO: A fibrilacao atrial (FA) isolada promove mudancas eletrofisiologicas, chamadas de remodelamento eletrico, facilitando sua recorrencia e manutencao. Ha evidencia de que o processo de remodelamento seja reversivel apos a recuperacao do ritmo sinusal (RS). Entretanto, o momento para a recuperacao das propriedades eletrofisiologicas ainda nao foi definido. OBJETIVO: O objetivo desse estudo foi avaliar a ativacao eletrica atrial usando o eletrocardiograma de alta resolucao de onda P (P-ECGAR) pos-cardioversao da FA de longa duracao, concentrando-se no processo de remodelamento reverso para identificar o momento da estabilizacao do processo. METODOS: Individuos com FA isolada persistente, candidatos a cardioversao com conversao bem-sucedida ao RS, foram incluidos no estudo. A P-ECGAR foi realizada imediatamente apos a reversao ao ritmo sinusal e repetida apos 7 e 30 dias. RESULTADOS: Dentre os 31 individuos, 9 apresentaram recorrencia precoce da FA, todos nos primeiros 7 dias apos a cardioversao, e 22 permaneceram em RS por pelo menos um mes; o ECGAR foi obtido no setimo e no trigesimo dias apos a cardioversao. No 30o dia, a duracao da onda P progressivamente diminuiu do primeiro para o terceiro ECGAR (duracao da onda P: 185,5±41,9 m/s vs 171,7±40,5 m/s vs 156,7±34,9 m/s, respectivamente, 1o, 2o e 3o ECGAR; p<0,001 para todas as comparacoes). Na analise de dominio de frequencia, a turbulencia espectral nao foi aparente no ECGAR imediatamente apos a cardioversao, mas aumentou de forma aguda no 7o dia e permaneceu inalterada no 30o dia. CONCLUSAO: O presente estudo sugere que os primeiros sete dias pos-cardioversao, apos FA de longa duracao, sao criticos para o processo de remodelamento reverso e recorrencia da arritmia.BACKGROUNDnAtrial fibrillation (AF) itself promotes electrophysiological changes, termed electrical remodeling, facilitating its recurrence and maintenance. There is evidence that the remodeling process is reversible after restoration of the sinus rhythm (SR). However, the timing for the recovery of electrophysiological properties is still undefined.nnnOBJECTIVEnThe aim of this study was to assess the atrial electrical activation using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing AF, focusing on the reversal remodeling process to identify the timing of the process stabilization.nnnMETHODSnSubjects with lone persistent AF, eligible for cardioversion and successfully converted to SR, were enrolled at the study. SAECG was performed immediately after reversion to SR and repeated on days seven and thirty.nnnRESULTSnOf 31 subjects, nine presented early recurrence of atrial fibrillation, all of them in the first seven days post-cardioversion; 22 remained in SR for at last one month and SAECG was obtained on days seven and thirty after cardioversion. In the latter, P-wave duration progressively abated from the first to the third SAECG (P-wave duration: 185.5+/-41.9 ms vs 171.7+/-40.5 ms vs 156.7+/-34.9 ms, respectively, first, second and third SAECG; p<0.001 for all matches). In the frequency domain analysis, spectral turbulence was not apparent in SAECG immediately post-cardioversion, but sharply increased on day seven and remained unchanged on day thirty.nnnCONCLUSIONnThis study suggests that the first seven days post-cardioversion of long standing AF are critical for reversal remodeling process and arrhythmia recurrence.

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração

FUNDAMENTO: A fibrilacao atrial (FA) isolada promove mudancas eletrofisiologicas, chamadas de remodelamento eletrico, facilitando sua recorrencia e manutencao. Ha evidencia de que o processo de remodelamento seja reversivel apos a recuperacao do ritmo sinusal (RS). Entretanto, o momento para a recuperacao das propriedades eletrofisiologicas ainda nao foi definido. OBJETIVO: O objetivo desse estudo foi avaliar a ativacao eletrica atrial usando o eletrocardiograma de alta resolucao de onda P (P-ECGAR) pos-cardioversao da FA de longa duracao, concentrando-se no processo de remodelamento reverso para identificar o momento da estabilizacao do processo. METODOS: Individuos com FA isolada persistente, candidatos a cardioversao com conversao bem-sucedida ao RS, foram incluidos no estudo. A P-ECGAR foi realizada imediatamente apos a reversao ao ritmo sinusal e repetida apos 7 e 30 dias. RESULTADOS: Dentre os 31 individuos, 9 apresentaram recorrencia precoce da FA, todos nos primeiros 7 dias apos a cardioversao, e 22 permaneceram em RS por pelo menos um mes; o ECGAR foi obtido no setimo e no trigesimo dias apos a cardioversao. No 30o dia, a duracao da onda P progressivamente diminuiu do primeiro para o terceiro ECGAR (duracao da onda P: 185,5±41,9 m/s vs 171,7±40,5 m/s vs 156,7±34,9 m/s, respectivamente, 1o, 2o e 3o ECGAR; p<0,001 para todas as comparacoes). Na analise de dominio de frequencia, a turbulencia espectral nao foi aparente no ECGAR imediatamente apos a cardioversao, mas aumentou de forma aguda no 7o dia e permaneceu inalterada no 30o dia. CONCLUSAO: O presente estudo sugere que os primeiros sete dias pos-cardioversao, apos FA de longa duracao, sao criticos para o processo de remodelamento reverso e recorrencia da arritmia.BACKGROUNDnAtrial fibrillation (AF) itself promotes electrophysiological changes, termed electrical remodeling, facilitating its recurrence and maintenance. There is evidence that the remodeling process is reversible after restoration of the sinus rhythm (SR). However, the timing for the recovery of electrophysiological properties is still undefined.nnnOBJECTIVEnThe aim of this study was to assess the atrial electrical activation using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing AF, focusing on the reversal remodeling process to identify the timing of the process stabilization.nnnMETHODSnSubjects with lone persistent AF, eligible for cardioversion and successfully converted to SR, were enrolled at the study. SAECG was performed immediately after reversion to SR and repeated on days seven and thirty.nnnRESULTSnOf 31 subjects, nine presented early recurrence of atrial fibrillation, all of them in the first seven days post-cardioversion; 22 remained in SR for at last one month and SAECG was obtained on days seven and thirty after cardioversion. In the latter, P-wave duration progressively abated from the first to the third SAECG (P-wave duration: 185.5+/-41.9 ms vs 171.7+/-40.5 ms vs 156.7+/-34.9 ms, respectively, first, second and third SAECG; p<0.001 for all matches). In the frequency domain analysis, spectral turbulence was not apparent in SAECG immediately post-cardioversion, but sharply increased on day seven and remained unchanged on day thirty.nnnCONCLUSIONnThis study suggests that the first seven days post-cardioversion of long standing AF are critical for reversal remodeling process and arrhythmia recurrence.

Detection of Incipient Left Ventricular Hypertrophy in Mild to Moderate Arterial Hypertension with Normal Electrocardiogram and Echocardiogram. A New Use for Signal-Averaged Electrocardiography

OBJECTIVEnTo assess signal-averaged electrocardiogram (SAECG) for diagnosing incipient left ventricular hypertrophy (LVH).nnnMETHODSnA study with 115 individuals was carried out. The individuals were divided as follows: GI - 38 healthy individuals; GII - 47 individuals with mild to moderate hypertension and normal findings on echocardiogram and ECG; and GIII - 30 individuals with hypertension and documented LVH. The magnitude vector of the SAECG was analyzed with the high-pass cutoff frequency of 40 Hz through the bidirectional four-pole Butterworth high-pass digital filter. The mean quadratic root of the total QRS voltage (RMST) and the two-dimensional integral of the QRS area of the spectro-temporal map were analyzed between 0 and 30 Hz for the frequency domain (Int FD), and between 40 and 250 Hz for the time domain (Int TD). The electrocardiographic criterion for LVH was based on the Cornell Product. Left ventricular mass was calculated with the Devereux formula.nnnRESULTSnAll parameters analyzed increased from GI to GIII, except for Int FD (GII vs GIII) and RMST log (GII vs GIII). Int TD showed greater accuracy for detecting LVH with an appropriate cutoff > 8 (sensitivity of 55%, specificity of 81%). Positive values (> 8) were found in 56.5% of the G II patients and in 18.4% of the GI patients (p< 0.0005).nnnCONCLUSIONnSAECG can be used in the early diagnosis of LVH in hypertensive patients with normal ECG and echocardiogram.

Modificação do nódulo sinusal via cateter por energia de radiofreqüência em paciente com taquicardia sinusal inapropriada. Avaliação dos resultados imediatos e tardios

This article reports the early and late results of a patient in whom radiofrequency current was used to ablate an incessant inappropriate sinus tachycardia. During successful radiofrequency application there was a sudden change of rate and subsequent emergence of a stable rhythm with the same sinus node P wave characteristics. During follow-up, normal cardiac cycles were still present after six months of the procedure, although the patient still complained of palpitations, suggesting no correlation with the heart rate.

O significado da abstinência do álcool na cardiomiopatia alcoólica com disfunção ventricular moderada

OBJETIVO: Avaliar o papel da abstencao alcoolica, no periodo de 12 meses, na cardiomiopatia alcoolica (CMA) com disfuncao ventricular de grau moderado, em pacientes tratados com esquema anticongestivo. METODOS: Estudo observacional prospectivo com 20 pacientes com CMA, 9 (45%) na classe funcional (CF) II e 11(55%) na CF III, 16 (80%) homens, predominio de negros (55%), de 35 a 56 (x=45) anos, com consumo pesado de alcool (>80g etanol/dia), por periodo de 51 a 112 (x=85) meses, que concordaram, inicialmente, em participar de programa de apoio, com psicoterapia de grupo, alem do acompanhamento clinico com realizacao de exames nao invasivos, antes do inicio do programa e apos 12 meses da terapia, e foram divididos em dois grupos, o 1 (G-I) constituido pelos que atingiram a abstinencia e o 2 (G-II) pelos nao abstemios. RESULTADOS: Apos 12 meses, 11 (55%) pacientes permaneciam em terapia de apoio, 8 (72,72%) no G-I, enquanto os 9 (45%) que nao se mantiveram no programa, apenas 2 (22,22%) tinham logrado abstinencia (G-I). Ao fim da avaliacao, alcancamos numero igual de pacientes entre os grupos. Comparando os grupos observamos: a) menores valores medios dos diâmetros sistolico (DSVE) e diastolico (DDVE) do ventriculo esquerdo no G-I; b) maior numero de internacoes no G-II (3) em relacao ao G-I (1); c) na evolucao clinica, maior numero de pacientes do G-I, entre os que apresentaram melhoras (3 G-I e 1 G-II) e que permaneceram inalterados (6 G-I e 3 G-II), alem do maior numero de pioras entre o G-II (1 G-I e 5 G-II). CONCLUSAO: Apesar do desejo inicial favoravel, a abstinencia so foi obtida em 50% dos pacientes com CMA e disfuncao ventricular moderada, porem, quando alcancada, apresentou melhor evolucao (melhoras + inalterados = 90%), com maior reducao do DSVE e do DDVE (p<0,001), devendo sempre ser perseguida mesmo na presenca de moderada disfuncao ventricular.

Radiofrequency catheter ablation of an incessant supraventricular tachycardia initiated by a Hisian parasystole.

The coexistence of a pamsystolic focus, tachycardia dependent right bundle branch aberrancy, and an AV accessory pathway is reported here. This condition was present in a 40‐year‐old man, which led to an incessant AV reciprocating tachycardia. Further electrophysiological study revealed that the parasystolic focus was located somewhere in the His bundle; endocardial mapping disclosed a right posterior accessory pathway. Radiofrequency current was delivered at the atrial level of the right posterolateral AV groove and successfully ablated the accessory pathway, leading to a dramatic improvement in cardiac function. In conclusion, the recognition of the electrophysiological mechanism of incessant Supraventricular tachycardia was of crucial importance for the therapy decision. A definitive intervention using radiofrequency catheter ablation should be considered early and not postponed in patients with tachycardia‐induced cardiomyopathy.