Ionic mechanisms and vectorial model of early repolarization pattern in the surface electrocardiogram of the athlete.

BACKGROUND: The electrocardiogram (ECG) of the athlete displays particular characteristics as a consequence of both electrophysiological and autonomic remodeling of the heart that follows continued physical training. However, doubts persist on how these changes directly interact during ventricular activation and repolarization ultimately affecting surface ECG waveforms in athletes. OBJECTIVE: This article considers an in deep rationale for the electrocardiographic pattern known as early repolarization based on both electrophysiological mechanisms at cellular level and the vectorial theory of the cardiac activation. METHODS: The mechanism by which the autonomic remodeling influences the cardiac electrical activation is reviewed and an insight model of the ventricular repolarization based on ionic models and the vectorial theory of the cardiac activation is proposed. RESULTS: Considering the underlying processes related to ventricular electrical remodeling, we propose that, in athletes' heart: 1) vagal modulation increases regional electrophysiological differences in action potential phases 1 and 2 amplitudes, thus enhancing a voltage gradient between epicardial and endocardial fibers; 2) this gradient affects depolarization and repolarization timing sequences; 3) repolarization wave front starts earlier on ventricular wall and partially overcomes the end of depolarization causing an upward displacement of the J-point, ST segment elevation, and inscription of magnified T-waves amplitudes leading to characteristic surface ECG waveform patterns. CONCLUSIONS: In athletes, the association between epicardial to endocardial electrophysiological differences and early repolarization ECG pattern can be demonstrated by the vectorial theory of the ventricular activation and repolarization.

Spectral turbulence analysis of the signal-averaged electrocardiogram of the atrial activation as predictor of recurrence of idiopathic and persistent atrial fibrillation.

The frequency domain analysis of the P-wave signal-averaged ECG (P-SAECG) is able to identify patients at risk for lone atrial fibrillation (AF) after cardioversion to sinus rhythm. The terminal portion of the P-wave of right precordial leads on 12-lead ECG is associated with electrical abnormalities in the atria. The aim of this study was to assess the spectral turbulence analysis (STA) of the P-SAECG as a predictor of recurrence of idiopathic AF. STA was performed in 41 patients with 2 or more symptomatic episodes of idiopathic and persistent AF after successful electrical cardioversion and drug-free state (Group A), and in 25 control individuals during sinus rhythm (Group B), matched by age, gender, and P-wave duration. The orientation of the terminal portion (positive or negative) of the Z-lead was assessed as representing right precordial leads potentials. After 6 months follow-up, Group A was divided into two groups according to recurrence: G-A1--at least one recurrence (21 patients), and G-A2--no recurrence (20 patients). Fragmented electrical activity (FEA) was observed in 19 patients of G-A1 and in 2 of G-A2 (odds ratio = 85.5; p<<0.001). STA showed 90.5% sensitivity and 90.0% specificity for early recurrence of AF. After 12 months, no patients of G-A2 and 15 of G-A1 developed >3 episodes of persistent AF, being FEA observed in 13 (odds ratio = 14.6, p = 0.002). No episodes of AF were observed in Group B. Average time for recurrence of FEA positive patients (4.3 +/- 0.7 months) was significantly shorter than of G-A2 (7.4+/-0.7 months), and log-rank analysis revealed significant difference of event-free rate over time (p = 0.004). In a logistic regression model FEA, use of amiodarone and a positive terminal portion of the Z-lead of the P-SAECG were independent predictors of recurrence of idiopathic and persistent AF.

Analysis of the prevalence of ventricular late potentials in the late phase of myocardial infarction based on the site of infarction.

OBJECTIVE: The initial site of myocardial infarction (MI) may influence the prevalence of ventricular late potentials (VLP), high-frequency signals, due to the time course of ventricular activation. The prevalence of VLP in a period of more than 2 years after acute MI was assessed focusing on the initially injured wall. METHODS: The prevalence of VLP in a late phase after MI (median of 924 days) in anterior/antero-septal and inferior/infero-dorsal wall lesion was analyzed using signal-averaged electrocardiogram in time domain. The diagnostic performance of the filters employed for analysis on was tested at high-pass cut-off frequencies of 25 Hz, 40 Hz and 80 Hz. RESULTS: The duration of the ventricular activation and its terminal portion were larger in inferior than anterior infarction, at high-pass cut-off frequencies of 40 Hz and 80 Hz. In patients with ventricular tachycardia, these differences were more remarked. The prevalence of ventricular late potentials was three times greater in inferior than anterior infarction. CONCLUSION: Late after myocardial infarction, the prevalence and the duration of ventricular late potentials are greater in lesions of inferior/infero-dorsal than anterior/antero-septal wall confirming their temporal process, reflecting their high-frequency content.

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.

Noninvasive cardiac assessment in children of women with systemic lupus erythematosus.

OBJECTIVE: Noninvasive cardiac assessment of newborns and infants of women with systemic lupus erythematosus. The children had no congenital total atrioventricular block and were compared with the children of healthy women. METHODS: We prospectively assessed 13 newborns and infants aged 1 to 60 days, children of women with systemic lupus erythematosus and without congenital total atrioventricular block. These children were compared with 30 children of women who had no lupus or anti-Ro/SSA antibodies, and no risk factors for congenital heart disease either. Their age groups matched. The following examinations were performed: cardiological physical examination, electrocardiography, echocardiography, and signal-averaged electrocardiography. RESULTS: The statistical analysis showed no significant difference in ventricular function or in the cardiac conduction system between the groups. CONCLUSION: In regard to the conduction system and ventricular function in the absence of total atrioventricular block, no statistically significant difference was observed between the children of women with systemic lupus erythematosus and children of healthy women.

Ritmo com complexos QRS pouco alargados e sem atividade atrial: qual é o mecanismo ? / Narrow QRS complex rhythm without atrial activity: what is the mechanism?

Paciente admitido em fase aguda de infarto do miocárdio apresentou registro eletrocardiográfico não usual. Os aspectos pertinentes do registro para a elucidação diagnóstica são discutidos.

A patient admitted with acute myocardial infarction presented an unusual electrocardiographic record. Therelevant aspects of the record for confirming the diagnosis are discussed.

O eletrocardiograma no ritmo de átrio esquerdo / Electrocardiogram - left atrial rhythm

O ritmo de átrio esquerdo foi descrito por Mirowski, em 1960, ao registrar no ECG ondas P negativas nas derivações D1 e V6 e positivas em V1. Posteriormente, novos estudos demonstraram ondas P negativas também em D2, aVL e V6, indicando que o vetor espácial de P orientava-se para a direita, de cima para baixo e para a frente. Também em 1960, Harris et al. reproduziram em humanos esse ritmo, empregando um pacing na junção da veia pulmonar direita inferior e o átrio esquerdo, obtendo ondas P negativas em D2, D3, aVFe de V4 a V6, confirmando o mecanismo dessa anomalia elétrica.

Efeito da sazonalidade tropical sobre os resultados do teste da mesa de inclinação / Seasonal fluctuation of tilt-test outcomes in the tropics

Fundamentos: Ambientes com temperatura elevada são considerados facilitadores para o desenvolvimento de síndrome neurocardiogênica. No entanto, existem poucas informações a respeito dos efeitos da sazonalidade nos resultados do teste da mesa de inclinação. Objetivo: Avaliar a influência da sazonalidade na taxa de positividade do teste de inclinação em uma cidade de clima tropival. Métodos: Foram analisados 501 testes consecutivos realizados em duas instituições na cidade do Rio de Janeiro, de junho de 2003 a agosto 2008, em uma população cuja idade variou de 6 anos a 90 anos, sendo 39 por cento homens. A resposta ao teste foi considerada positiva de acordo com os critérios do VASIS. O resultado do exame foi comparado no período de acordo com a taxa de positividade média mensal e sazonal. Após ter sido assumida a normalidade das distribuições e verificada a homocedasticidade através do teste de Bartlett, os achados foram comparados, utilizando-se os testes one-way ANOVA, para medidas não repetidas. Os resultados...

Background: High-temperature environments are rated as triggers for vaso-vagal orthostatic intolerance (VOI). However, there is little information on seasonal fluctuations of head-up tilt table test (HUT) outcomes.Objective: To evaluate seasonal fluctuation in HUT outcomes in a tropical city. Methods: We assessed 501 consecutive HUTs conducted at two institutions in the city of Rio de Janeiro, from June 2003 to August 2008 (6 y.o to 90.y.o, 39% males). The test response was defined as positive by the VASIS criteria. The VOI positive (+) outcome rate was compared during the period with the average monthly andseasonal rates. Having tested normality assumption and homocedasticity through the Bartlett test, the findingswere compared through one-way ANOVA tests for nonrepeatedmeasurements. The outcomes are presented as mean±DP. Results: The VOI was positive in 30.3%. Normality(Std Skewness: 1.5±0.4; Std Kurtosis: -0.4±0.8) and homocedasticity assumptions were accepted in all groups. No significant differences were observed in the monthly or seasonal average rates of VOI+ outcome in all comparisons (respectively, p=NS and p=NS). Conclusions: In the city of Rio de Janeiro, positive outcomes for HUT present uniform distribution throughout the year for months and seasons.

A evolução do eletrodo no registro dos potenciais elétricos cardíacos: um pouco de história / The development of the electrode for recording cardiac electrical potentials: a brief history

O presente artigo é uma história resumida sobre os primeiros empregos de eletrodos para o registro dasdiferenças de potenciais elétricos entre duas áreas do coração humano. Os eletrodos são usados desde meadosdo século XIX até a atualidade e, principalmente, após a construção do galvanômetro de corda original criadopor Willem Einthoven, em 1901, na Holanda. Após a definição matemática dos potenciais elétricos originadosdo coração, postulada por Einthoven durante a primeira década do século XX, outros autores como Sir Thomas Lewis (Inglaterra), Frank Wilson e E. Goldberger (EUA), Sodi-Pallares (México) e outros, aprimoraramos registros eletrocardiográficos e sua interpretação, baseados na teoria vetorial de Wilson, a qual é aindausada na prática médica. Atualmente, os eletrodos são usados largamente como uma simples e pequena placa de metal no ECG de repouso na prática diária,no ECG dinâmico, nos monitores, nos laboratórios de pesquisa, nos métodos invasivos e nos marca-passos. Esta é a grande importância de um simples eletrodo, que não chama muito a atenção por ser uma coisa tão simples, mas que é de grande importância para a vida profissional.

This paper offers a brief history of the electrode: a simple but very important instrument for recording the differences of potentials between two electrical areas of the human heart. Electrodes have been used since the mid-XIX century through to the present day, afterthe original string galvanometer was developed by Willem Einthoven in 1901 in the Netherlands. Based on the mathematical definition of the electrical potentials originating from the heart postulated by Einthoven during the first decade of the XX century with hisgalvanometer, other authors such as Sir Thomas Lewis (England), Frank Wilson and E. Goldberger (USA), and Sodi-Pallares (Mexico) improved electrocardiographic recordings and their interpretations, based on thevectorial theory of Wilson, which is still used in medical practice. Today, electrodes are widely used asa simple metal plates for recording the rest ECG in the clinical practice and for monitoring the ECG in research laboratories, in catheters for electrophysiological studies and as well as in pace-makers. This reflects the great importance of the simple electrode, which attracts little attention but is extremely important for medicalpractitioners.

Turbulência elétrica e risco de arritmia ventricular no infarto do miocárdio em paciente idoso / Electrical turbulence and risk of ventricular arrhythmia in myocardial infarction in an elderly patient

Idoso foi admitido no hospital com queixas de tonteiras, palpitações e história de infarto do miocárdio recente.Durante o exame clínico constataram-se várias extrassístoles. O eletrocardiograma de repouso (ECG)registrou infarto do miocárdio. Foram realizados ecocardiograma bidimensional, vetocardiograma eeletrocardiograma de alta de resolução (ECGAR) com o objetivo de estratificar o risco de arritmias ventriculares letais e morte súbita. O ECG registrou a presença de infarto do miocárdio da parede inferior recente e o ECGAR detectou a presença de potenciais ventriculares fragmentados e turbulência elétrica, mas não foramregistradas taquicardias ventriculares durante o estudo.

Relação entre as alterações eletrocardiográficas e a localização da massa muscular hipertrofiada na cardiomiopatia hipertrófica / Relationship between electrocardiographic changes and the localization of the hypertrophic muscular mass in hypertrophic cardiomyopathy

Foram estudadas as alteraçöes eletrocardiográficas em 33 pacientes portadores de cardiomiopatia hipertrófica da forma obstrutiva e näo obstrutiva. Baseado na localizaçäo da massa muscular hipertrófica, os pacientes divididos em 3 grupos: septal dominante, ântero-medial dominante e ântero-apical dominante. O eletrocardiograma anormal foi observado em 32 (93,9%). As alteraçöes eletrocardiográficas foram: inversäo da onda T (78,8%), sinais de hipertrofia ventricular esquerda (69,7%), sinais de aumento do átrio esquerdo (60,6%) e ondas Q patológicas (30,0%). As alteraçöes da onda T foram mais expressivas no grupo ântero-apical dominante, no qual 87,5% apresentaram ondas T com grau de inversäo superior a 5 mm. Os sinais eletrocardiográficos de hipertrofia ventricular esquerda foram mais observados (76,6%) nos casos que apresentaram a parede ântero-medial comprometida com um grau de hipertrofia maior que 1,5 cm independente do grupo. O aumento do átrio esquerdo, avaliado através do índice de Morris, esteve presente em 20 casos (60,6%). Embora esta alteraçäo eletrocardiográfica tenha sido mais freqüente nos pacientes com aumento do diâmetro diastólico desta cavidade, o aumento do índice de Morris foi encarado como dependente dos distúrbios da conduçäo intra-atrial. As ondas Q patológicas foram interpretadas como representativas de zonas de necrose, quando presentes em mais de uma regiäo. Nas demais eventualidades, elas poderiam estar relacionadas com os desvios dos vetores de despolarizaçäo ventricular

Hipocalcemia causando insuficiência cardíaca / Hypocalcemia causing myocardial failure

Paciente do sexo feminino, de 39 anos, com insuficiência cardíaca refratária. Em 2/82 havia sido submetida a tireiodectomia lobar direita por bócio difuso hiperplásico e, em 8/84, a nova cirurgia tireiodiana para remoção de nódulo no lobo esquerdo. Um dia após, apresentou sinais de hipocalcemia, sendo diagnosticado hipoparatireoidismo secundário à ablação acidental das paraitreóides. Iniciou descompensação cardíaca esquerda culminando, sete meses após, com edema pulmonar agu-do. Nessa ocasião, apresentava cardiomegalia de grau II (ICT = 0,58), com predominância de câmaras esquerdas, confirmada pelo ecocardiograma que mostrava importante diminuição da contratilidade. O eletrocardiograma revelava aumento de intervalo QT (QTc = 0,55 s). A calcemia era de 5,0 mg/dl com calciúria de 28 mg/dia, fosfatemia de 4,8 mg/dl e fosfatúria de 214 mg/dia. Os níveis de hormônios tiretodianos (T3 e T4) estavam nos limites da normalidade, embora o TSH estivesse no início com valores aumentados. Foi tratada, inicialmente, com digital, diurético, vasodilatador, hormônio tireoidiano e cálcio oral. Somente logrou progressiva melhora hemodinâmica, quando doses mais elevadas de cálcio foram administradas, além da associação com a vitamina D3, normalizando a área cardíaca, estando hoje assintomática, somente em uso de hormônio tireoidiano, cálcio e vitamina D3

A 39 years-old female patient with refractory hears failure has been studied. On February, 1982 she was submitted to right lobar thyreoidectomy for remotion of the left thyreoidean lobe. Follow-ing the surgery, she had signs of hypocalcemia and the diagnosis of secondary hypoparathyreoidism and heart failure had been made. Seven months after she had acute pulmonary edema, cardiomegaly III (cardiothoracic index = 0.58) with predominant left atrial and left ventricular hypertrophy, which were confirmed by echocardiogram (ECO). The ECO also demonstrated low contractility of the left ventricle. The QT interval was increased on the electrocardiogram (QTc = 0.50 s), the calcium was 5.0 mg/dl with calciuria of 28 mg/ day; phosphatemia was 4.8 mg/dl and phosphaturia of 214 mg/day. The level of thyreoidean hormones (T3 and T4) were in the normal ranges despite the TSH was increased in the beginning of the disease. She was first treated with digitalis, diuretic and vasodilator drugs, thyreoidean hormone and oral calcium. She had progressive hemodynamic improvement when higher doses of calcium were given with D3 vitamin. The most significant result of this treatment was reduction of the heart size that come back to normal. At the present time patient is treated with thyreoidean hormone, calcium and D3 vitamin only

Influência da fibrilação atrial na história natural da cardiomiopatia hipertrófica / The Influence of Atrial Fibrillation in the Natural History of Hypertrophic Cardiomyopathy

PURPOSE--To evaluate the influence of atrial fibrillation in the natural history of hypertrophic cardiomyopathy. METHODS--Eighty-eight patients under ambulatory treatment were studied. Most of them presented the asymmetric type of hypertrophic cardiomyopathy (87.5 per cent). Group I (77 cases) was formed by patients who had never had atrial fibrillation and group II (11 cases) by those who had this arrhythmia paroxysmal or established. RESULTS--In group I, with ages 48.02 +/- 14.82 years, left atrial dimensions 4.21 +/- 0.66 cm, there was one sudden death; 69 were treated by clinical means and 7 by surgery; no patient developed thromboembolism neither cardiac failure. In group II, with ages 58.02 +/- 11.04 years and left atrial dimension 5.32 +/- 0.45 cm, there were 4 deaths, 4 thromboembolisms and 3 with cardiac failure; all received only clinical treatment, having improved in clinical status in 71.42 per cent after amiodarone therapy. CONCLUSION--Atrial fibrillation was present in 12.5 per cent, mostly in the asymmetric type, and in patients after 5th decade, all of them with enlarged left atrium (> 4.7 cm), with highest morbidity (thromboembolism and cardiac failure) and mortality. Among the survivors, amiodarone therapy improved functional class in 71.42 per cent

O eletrocardiograma de alta resoluçäo no domínio da frequencia. Utilizaçäo de técnicas estatísticas de correlaçäo espectral para identificaçäo de pacientes com taquicardia ventricular monomórfica sustentada / Frequency domain analysis of the signal averaged electrocardiograma. Application of estatistical techniques of spectral correlation for identification of patients with sustained monomorphic ventricular tachycardia

Objetivo - Avaliar uma melhoria da acurácia diagnóstica da taquicardia ventricular monomórfica (TVM), através do eletrocardiograma de alta resolução (ECGAR), adicionando à análise no domínio do tempo (DT), técnicas estatísticas de correlação espectral no domínio da freqüência (DF). Métodos - Foram estudados pelo ECGAR 137 indivíduos sendo 27 com cardiopatia e TVM sustentada, 30 com cardiopatia e sem TVM e 80 sem evidências de cardiopatia. Os parâmetros analisados no ECGAR no DT foram: duranção do QRS filtrado, RMS40 e LAS40 e, no DF, as médias e os devios padrões da correlação espectral intersegmentar do sinal e da banda de freqúência delimitadora da concentração do sinal. Resultados - A sensibilidade (Sb) e o valor preditivo positivo (VPP) do ECGAR no DT, DF e análise combinada de ambos os domínios foram, na detecção de TVM, respectivamente: Sb = 59,3 por cento, 63 por cento e 81,5 por cento e VPP = 80,0 por cento, 81,0 por cento e 84,6 por cento. Conclusão - A análise combinada do ECGAR nos DT e DF aumenta a acurácia diagnóstica de pacientes com apresentação clínica de TVM sustentada.

Ativaçäo atrial durante ritmo sinusal em pacientes com fibrilaçäo atrial paroxística reumática e näo reumática. Análise pela eletrocardiografia de alta resoluçäo no domínio da frequência / Atrial activation during sinus rhythm in patients with rheumatic and non-rheumatic paroxysmal atrial fibrillation. Frequency-domain analysis using signal-averaged electrocardiography

OBJECTIVE: Using P-wave signal-averaged electrocardiography, we assessed the patterns of atrial electrical activation in patients with idiopathic atrial fibrillation as compared with patterns in patients with atrial fibrillation associated with structural heart disease. METHODS: Eighty patients with recurrent paroxysmal atrial fibrillation were divided into 3 groups as follows: group I - 40 patients with atrial fibrillation associated with non-rheumatic heart disease; group II - 25 patients with rheumatic atrial fibrillation; and group III - 15 patients with idiopathic atrial fibrillation. All patients underwent P-wave signal-averaged electrocardiography for frequency-domain analysis using spectrotemporal mapping and statistical techniques for detecting and quantifying intraatrial conduction disturbances. RESULTS: We observed an important fragmentation in atrial electrical conduction in 27 percent of the patients in group I, 64 percent of the patients in group II, and 67 percent of the patients in group III (p=0.003). CONCLUSION: Idiopathic atrial fibrillation has important intraatrial conduction disturbances. These alterations are similar to those observed in individuals with rheumatic atrial fibrillation, suggesting the existence of some degree of structural involvement of the atrial myocardium that cannot be detected with conventional electrocardiography and echocardiography

Bloqueio atrioventricular total familiar em pacientes com cardiomiopatia hipertrófica / Familial complete atrioventricular block in patients with hypertrophic cardiomyopathy

A associação entre bloqueio atrioventricular (BAV) total espontâneo e cardiomiopatia hipertrófica é rara. Relatamos a ocorrência de três pacientes da mesma família que tiveram o diagnóstico de cardiomiopatia hipertrófica firmados por estudos hemodinâmico e angiográfico, com idades entre 19 e 41 anos. Foram tratados com implante de marcapasso cardíaco, estando atualmente assintomáticos, com idades entre 33 e 55 anos e em acompanhamento ambulatorial após 157 a 176 meses do aparecimento do BAV

The association of spontaneous complete heart block and hypertrophic cardiomyopathy is rare. We have studied three patients of the same family, two brothers and one nephew, ages 19-41 years, with hyperthrophic cardyomyopathy confirmed by hemodynamic and angyographic studies. All patients were treated with permanent cardiac pacemaker implant. They are assymptomatic, aging 33 to 55 years, with follow-up of 157 to 176 months after the onset of the heart block