Detection of incipient left ventricular hypertrophy in mild to moderate arterial hypertension with normal electrocardiogram and echocardiogram: a new use for signal-averaged electrocardiography.

OBJECTIVE: To assess signal-averaged electrocardiogram (SAECG) for diagnosing incipient left ventricular hypertrophy (LVH). METHODS: A 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. RESULTS: All 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). CONCLUSION: SAECG can be used in the early diagnosis of LVH in hypertensive patients with normal ECG and echocardiogram.

Detecção de hipertrofia ventricular esquerda incipiente na hipertensão arterial leve a moderada com eletrocardiograma e ecocardiograma normais. Um novo emprego do eletrocardiograma de alta resolução / Detection of incipient left ventricular hypertrophy in mild to moderate arterial hypertension with normal electrocardiogram and echocardiogram: a new use for signal-averaged electrocardiography

OBJECTIVE: To assess signal-averaged electrocardiogram (SAECG) for diagnosing incipient left ventricular hypertrophy (LVH). METHODS: A 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. RESULTS: All 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 percent, specificity of 81 percent). Positive values (> 8) were found in 56.5 percent of the G II patients and in 18.4 percent of the GI patients (p< 0.0005). CONCLUSION: SAECG can be used in the early diagnosis of LVH in hypertensive patients with normal ECG and echocardiogram

Cardiomiopatia arritimogênica do ventrículo direito. Valor preditivo da dispersäo do intervalo QT para avaliaçäo de risco arritmogênico e de morte súbita / Arrhythmogenic cardiomyopathy of the right ventricle. Predictive value of QT interval dispersion to assess arrhythmogenic risk and sudden death

OBJECTIVE: To 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. METHODS: We 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. RESULTS: (mean +/- SD). QT interval dispersion: patients = 53.8+/-14.1ms; control group = 35.0+/-10.6ms, p=0.001. Patients with induction of ventricular tachycardia: 52.5+/-13.8ms; without induction of ventricular tachycardia: 57.5+/-12.8ms, 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+/-12.8ms, p=0.852. Using a cutoff > or = 60ms 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 percent, a specificity of 57 percent, and positive and negative predictive values of 25 percent and 85 percent, respectively. CONCLUSION: Patients 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.

Síndrome de Brugada: observaçöes sobre a evoluçä de um caso / The Brugada syndrome: outcome of one case

The Brugada syndrome is a rare condition, and due to its mutating manner of presentation it may be difficult to diagnose. We report one case and discuss the diagnostic aspects and the clinical outcome of one patient with characteristic findings of this syndrome. These findings are especially defined by J-ST elevation in the right leads of serial electrocardiographic records, wide oscillations of J points and ST segments during 24-hour Holter monitoring, and nocturnal sudden death. We stress the importance of the Holter monitor findings for diagnostic complementation. Through this method it is possible to establish a correlation between vigil activities and sleep and the variability of the degree of impairment in ventricular repolarization.

Avaliaçäo de potenciais fragmentados em presença de bloqueio de ramo direito sem alteraçöes estruturais miocárdicas ventriculares. Estudo pelo eletrocardiograma de alta resoluçäo no domínio da frequência / Evaluation of fragmented potentials in the presence of right bundle branch block without structural myocardium abnormalities. Study made by signal-averaged electrocardiogram on time and frequency domain

Objetivo - Em ausência de alterações estruturais miocárdicas (AEM), avaliar se o bloqueio de ramo direito (BRD) gera potenciais fragmentados (PF) e turbulência espectral (TE) no eletrocardiograma de alta resolução (ECGAR). Métodos - Doze crianças com comunicação interatrial (CIA) e bloqueio incompleto do ramo direito (BIRD) sem AEM (Grupo I), foram comparadas com 17 crianças com tetralogia de Fallot (TF) operada, BCRD e AEN, 5 com extra sistoles ventriculares e 2 com taquicardia ventricular sustentada (Grupo II). Todas fizeram ECGAR nos domínios do tempo (DT) e da freqüência (DF), com cinco variáveis analisadas. Resultados - Os pacientes do grupo I tiveram as variáveis normais apesar do BIRD. No grupo II, 4 das cinco variáveis foram anormais, sugerindo a presença de PF e TE atribuíveis a AEM inerentes à malformação e ao ato cirúrgico. Conclusão - Na CIA o BIRD não complicado de AEM não gera PF e TE, não constituindo fator de risco para taquicardia ventricular sustentada.

O eletrocardiograma de alta resoluçäo durante taquicardia ventricular / The Signal-Averaged Electrocardiogram During Ventricular Tachycardia

PURPOSE--To evaluate by the signal averaged-ECG (SAECG) the initial portion of the activation of the sustained ventricular tachycardia (SVT) and monomorphic repetitive ventricular tachycardia (MRVT), correlating the findings with those obtained during sinus rhythm (SR). METHODS--Ten patients was studied; five with SVT and five with MRVT. Patients with SVT presented a positive SAECG while patients with MRVT the test was negative, during SR. The findings of this two populations were compared with those obtained in a group of ten patients with advanced bundle branch block (ABBB--five RBBB and five LBBB). We analyzed in the vector-magnitude obtained during VT and ABBB, the root mean square of the initial 40 ms portion of the activation (RMS40) and the duration of the low amplitude signals < 40 microV from the beginning of the filtered QRS (LAS). To define the positiveness of the test in SR, we analyzed the final RMS40 (normal > 20 microV), the duration of the LAS < 40 microV at the end of the activation (normal < 38 ms) and the total QRS duration (QRSD-normal < 114 ms). RESULTS--(mean)-SVT in SR: RMS40 = 11.2 +/- 6.2 microV; LAS = 47.4 +/- 5.8 ms; QRSD = 131.2 +/- 8.7 ms. SVT during VT: RMS40 = 6.9 +/- 4.5 microV; LAS = 54.5 +/- 9.1 ms. RMVT in SR: RMS40 = 59.7 +/- 49.0 microV; LAS = 28.3 +/- 8.5 ms; QRSD = 93.1 +/- 13.0 ms. MRVT during VT: RMS = 25.2 +/- 8.8 microV; LAS = 28.9 +/- 11.1 ms. RBBB: RMS = 53.3 +/- 34.2 microV; LAS = 22.6 +/- 9.8 ms. LBBB: RMS = 54.7 +/- 37.3 microV; LAS = 11.4 +/- 4.6 ms. The comparison between the data from SVT and MRVT/ABBB showed p < 0.01. CONCLUSION--In the studied population, the SAECG was able to identify abnormal LAS initiating SVT, that were not present in MRVT and ABBB. This signals probably represents intra-myocardial slow conduction, as a portion of a re-entry circuit. There was an excellent correlation between the findings during SVT and MRVT with those obtained in SR

Taquicardia ventricular monomórfica repetitiva / Repetitive Monomorphic Ventricular Tachycardia

PURPOSE--To evaluate retrospectively clinical features of repetitive monomorphic ventricular tachycardia (RMVT). METHODS--Files of 11 patients with RMVT were analyzed (9 females, mean-age 37 +/- 17 years). All patients were submitted to clinical evaluation, ECG, Holter monitoring stress test, high-resolution ECG and echocardiogram; they were treated with antiarrhythmic drugs. RESULTS--Patients were in NYHA class I or II, 9 asymptomatics and 2 with palpitations. The ECG was normal in all of them. Cardiac memory was observed in 3. A left bundle branch block with inferior axis deviation in the frontal plane was present during RMVT in all patients (right ventricular outflow tract focus). Holter monitoring revealed mean of 12031 +/- 8345 isolated PVC/24h; 2892 +/- 234 ventricular couplets/24h and 1367 +/- 890 VTs/24h (mainly nonsustained). In 6 patients RMVT was suppressed during maximal exercise treadmill. High-resolution ECG was negative in all group. Five patients had a normal echocardiogram while 5 showed mitral valve prolapse. One patient developed tachycardiomyopathy. The arrhythmia was controlled with 320mg of oral sotalol in 3 of 4 that used this drug and with 120mg oral propranolol in one of 6 that used this drug. Drug resistance was present in the others. The mean follow-up period was 38 +/- 16 months. CONCLUSION--The results demonstrate that RMVT is a benign form of VT with no detectable anatomic substract by the currently used methods. It is probably induced by nonreentrant mechanism and frequently drug resistance is observed. Among the antiarrhythmic drugs commonly used, sotalol showed to be the most effective

Objetivo - Avaliar, retrospectivamente, os dados clínicos mais relevantes da taquiarritmia ventricular monomórfica repetitiva (TVMR). Métodos - Foram analisados os registros de 11 pacientes, 9 femininos, idade média de 37±17 anos, portadores de TVMR, todos submetidos à avaliação clínica seqüencial, ECG, Holter, prova de esforço em esteira, ECG de alta resolução (ECGAR) e ecocardiograma, sendo tratados com drogas antiarrítmicas. Resultados - Os pacientes encontravam-se em classe funcional I/II da NYHA, sendo 9 assintomáticos e 2 com queixas de palpitações. O ECG, em ritmo sinusal, foi normal nos 11 pacientes, havendo em 3 o fenômeno de memória cardíaca. O ECG durante a taquicardia mostrou QRS com BRE e eixo inferior no plano frontal (foco em via de saída de VD) em todo o grupo. O Holter mostrou no total dos pacientes, média de 12031±8345 extra-sístoles nas 24h; pareadas de 2892±234 e surtos de TV de 1367±890, a maioria não-sustentados. A prova de esforço aboliu a taquiarritmia no esforço máximo em 6 pacientes. O ECGAR foi negativo em todo o grupo. Cinco pacientes apresentavam ecocardiogramas normais, havendo em 5, sinais de prolapso da válvula mitral. Um paciente evoluiu com sinais de taquicardiomiopatia. A arritmia foi controlada em 3 pacientes com 320mg de sotalol VO (4 fizeram uso desta droga) e em 1 com 120mg de propranolol VO (usado em 6 pacientes), havendo nos restantes resistência medicamentosa. O tempo de seguimento médio foi de 38±16 meses. Conclusão - Os resultados indicaram ser a TVMR arritmia de evolução benigna, sem um substrato anatômico detectável pelos meios diagnósticos de rotina, desencadeada muito provavelmente por mecanismo eletrofisiológico não reentrante e com freqüente resistência medicamentosa. Dos antiarrítmicos utilizados de rotina, este estudo sugere ser o sotalol o mais efetivo

Variabilidade de R-R no infarto agudo anterior após a terapêutica trombolítica / Heart Rate Variability in Patients with Acute Anterior Myocardial Infarction and Thrombolytic Therapy

Objetivo - Avaliar os efeitos da trombólise sobre a integridade do sistema nervoso autônomo , em pacientes com infarto agudo do miocárdio de parade anterior, através da determinação da variabilidade de R-R. Métodos - Em 31 pacientes com infarto agudo de parade anterior, submetidos a terapêutica trombolítica (25 masculinos; idade 59 ± 14 anos), determinou-se por gravações de Holter de 24 h, as variabilidades de R-R. Utilizou-se um sistema de medidas algorítmicas, acoplado a um micro 286, determinando-se as flutuações de R-R durante ritmo sinusal e por períodos sucessivos de 5 min. Os resultados foram expressos como a média global de todos os períodos determinados, o desvio padrão da média de todos os períodos computados e a média dos desvios padrões dos intervalos processados. Valores inferiores a 50 ms dos desvios padrões das médias e das médias dos desvios padrões foram considerados anormais. Utilizou-se como critério de reperfusão a associação de um pico enzimático precoce de CKMB (£ 12 h), com a redução em 50% ou mais no grau de supra desnível de segmento ST dentro da lª hora após o início da terapêutica trombolítica e o aparacimento de ritmo idioventricular acelerado dentro do mesmo período. Separaram-se os pacientes em reperfundidos (grupo 1; n: 16) e não reperfundidos (grupo 2; n: 15). Resultados - Média de R-R: grupo 1 = 716±84 ms (variações de 540 a 820 ms); grupo 2: 595±115 ms (variações de 390 a 870 ms - p < 0,01). Desvio padrão de R-R: grupo 1 = 67±19 ms (variações de 34 a 92 ms); grupo 2: 50±14 ms (variações de 23 a 67 ms - p < 0,01). Variações de R-R inferiores a 50 ms: grupo 1 = 2 pacientes; grupo 2 = 5 pacientes. Média dos desvios padrões de R-R: grupo 1 = 44±14 ms (variacões de 26 a 65 ms); grupo 2: 39±17 ms (variações de 19 a 69 ms - p: ns). Conclusão - Pacientes com infarto agudo anterior beneficiados por trombólise química, apresentam maior variabilidade de R-R; esses resultados sugerem uma resposta mais adequada do sistema nervoso autônomo frente a patência vascular, havendo possíveis efeitos sobre o prognóstic

Purpose - To analyse the effects of thrombolysis on the integrity of the autonomic nervous system, in patient with acute myocardial infarction (AMI) of the anterior wall, using the determination of the heart rate variability. Methods - We prospectively evaluated the R-R variability of the 31 consecutive pattents with anterior AMI submitted to coronary thrombolysis 625 males; mean age 59±14 years) from Holter tapes. An algorythm in a 286 computer program was used for heart rate variability (HRV). With this system, R-R variations during synus rhythm and for a five consecutive minutes periods was determined. The results were expressed as the mean of the total determined periods; the standard deviation of the mean of all determined periods and the mean of the standard deviation. The reperfusion criteria was the early enzymatic rise of the CKMB activity levels (£ 12 h) combined with a 50% or more reduction in the ST segment elevation within the first hour after thrombolytic therapy and the presence of an accelerated idioventricular rhythm at the same time. The repefused group (group 1 = 16 patients) andnon-reperfused group (group 2 = 15 patients) were comparad in terms of R-R variability. Results - Mean R-R: group 1 = 716 ± 84 ms (540 - 820 ms); group 2 = 595 ± 115 ms (390 - 870 ms) - p < 0.02. SD of the R-R: group 1 = 67±19 ms (34 - 92 ms); group 2 = 50 ±14 ms (23 - 77 ms) - p < 0.01. HRV 50 ms: group 1 = 2 patients; group 2 = 5 patients. Means SD of the R-R: group 1 = 44 ± 14 ms (26 - 65 ms); group 2 = 39 ± 1 7 ms (19 -69 ms) - p:ns. Conclusion - Patients with anterior AMI and thrombolytic therapy demonstrate greater HRV; this finding suggested better integrity of the autonomic nervous system, with possible effects on prognosis

Diagnóstico eletrocardiográfico e vetocardiográfico dos bloqueios divisionais direitos / Electrocardiographic and vectocardiographic diagnosis of right divisional blocks

Foram estudados 13 eletrocardiogramas (ECG) e vetocardiogramas (VCG) de 25 pacientes que tinham critérios para o diagnóstico de bloqueios divisionais direitos (BDD). Dez tinham 1 BDD superior e 3 BDD inferior e todos incluíam ondas S espessas e com retardos em várias derivaçöes. O VCG explica tais aspectos e os critérios hoje aceitos para o diagnóstico dos BDD em cardiopatas e em indivíduos normais submetidos a esforço