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.

Remodelagem atrial elétrica reversa após cardioversão de fibrilação atrial isolada de longa duração / Remodelación atrial eléctrica reversa tras cardioversión de fibrilación atrial aislada de larga duración / Reversal atrial electrical remodeling following cardioversion of long-standing lone atrial fibrillation

FUNDAMENTO: A fibrilação atrial (FA) isolada promove mudanças eletrofisiológicas, chamadas de "remodelamento elétrico", facilitando sua recorrência e manutenção. Há evidência de que o processo de remodelamento seja reversível após a recuperação do ritmo sinusal (RS). Entretanto, o momento para a recuperação das propriedades eletrofisiológicas ainda não foi definido. OBJETIVO: O objetivo desse estudo foi avaliar a ativação elétrica atrial usando o eletrocardiograma de alta resolução de onda P (P-ECGAR) pós-cardioversão da FA de longa duração, concentrando-se no processo de remodelamento reverso para identificar o momento da estabilização do processo. MÉTODOS: Indivíduos com FA isolada persistente, candidatos à cardioversão com conversão bem-sucedida ao RS, foram incluídos no estudo. A P-ECGAR foi realizada imediatamente após a reversão ao ritmo sinusal e repetida após 7 e 30 dias. RESULTADOS: Dentre os 31 indivíduos, 9 apresentaram recorrência precoce da FA, todos nos primeiros 7 dias após a cardioversão, e 22 permaneceram em RS por pelo menos um mês; o ECGAR foi obtido no sétimo e no trigésimo dias após a cardioversão. No 30º dia, a duração da onda P progressivamente diminuiu do primeiro para o terceiro ECGAR (duração 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 comparações). Na análise de domínio de frequência, a turbulência espectral não foi aparente no ECGAR imediatamente após a cardioversão, mas aumentou de forma aguda no 7º dia e permaneceu inalterada no 30º dia. CONCLUSÃO: O presente estudo sugere que os primeiros sete dias pós-cardioversão, após FA de longa duração, são críticos para o processo de remodelamento reverso e recorrência da arritmia.

BACKGROUND: Atrial 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. OBJECTIVE: The 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. METHODS: Subjects 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. RESULTS: Of 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. CONCLUSION: This study suggests that the first seven days post-cardioversion of long standing AF are critical for reversal remodeling process and arrhythmia recurrence.

FUNDAMENTO: La fibrilación atrial (FA) aislada promueve cambios electrofisiológicos llamados "remodelación eléctrica", que facilitan su recurrencia y mantenimiento. Hay evidencia de que el proceso de remodelación sea reversible tras la recuperación del ritmo sinusal (RS). Sin embargo, el momento para la recuperación de las propiedades electrofisiológicas no está definido todavía. OBJETIVO: El objetivo de ese estudio fue evaluar la activación eléctrica atrial con el empleo del electrocardiograma de alta resolución de onda P (P-ECGAR) postcardioversión de la FA de larga duración, concentrándose en el proceso de remodelación reversa para identificar el momento de la estabilización del proceso. MÉTODOS: Se incluyeron en el estudio a individuos con FA aislada persistente y a candidatos a la cardioversión con conversión exitosa al RS. La P-ECGAR se realizó inmediatamente tras la reversión al ritmo sinusal y se repitió después de 7 y 30 días. RESULTADOS: Entre los 31 individuos, 9 presentaron recurrencia precoz de la FA, todos en los primeros 7 días después de la cardioversión, y 22 siguieron en RS durante un mes como mínimo; el ECGAR se obtuvo en el séptimo y en el trigésimo días tras la cardioversión. En el 30º día, la duración de la onda P disminuyó progresivamente desde el primer hasta el tercer ECGAR (duración de la onda P: 185,5±41,9 m/s vs 171,7±40,5 m/s vs 156,7±34,9 m/s, respectivamente, 1er, 2º y 3er ECGAR; p<0,001 para todas las comparaciones). En los análisis de dominio de frecuencia, la turbulencia espectral no fue aparente en el ECGAR inmediatamente tras la cardioversión, pero aumentó de forma aguda en el 7º día y siguió inalterada en el 30º día. CONCLUSIÓN: El presente estudio sugiere que los primeros siete días post cardioversión, después FA de larga duración, son críticos para el proceso de remodelación reversa y recurrencia de la arritmia.

Distúrbios da condução intraventricular - parte 2 / Intraventricular conduction disturbance - part 2

Na primeira parte desta revisão foram estudados os distúrbios da condução intraventricular, enfocados os bloqueios isolados tronculares e os fasciculares ou divisionais dos ramos direito e esquerdo.Na presente comunicação, enfatiza-se a frequente associação dos bloqueios tronculares com os fascuculares e, ainda, as características especiais dos chamados bloqueios de ramo fases 3 e 4.Especial atenção foi dada para os aspectos eletrocardiográficos diferenciados dos bloqueios focais ou intramurais, baseados em recentes estudos com o emprego do eletrocardiograma de alta resolução (ECGAR) e estudos eletrofisiológicos para a estratificação de risco de taquiarritimias ventriculares graves

Enalapril altera a formação da matriz colágena do miocárdio de ratos espontaneamente hipertensos / Enalapril alters the formation of the collagen matrix in spontaneously hypertensive rats

OBJECTIVE: To assess the effect of the inhibition of the angiotensin-converting enzyme on the collagen matrix (CM) of the heart of newborn spontaneously hypertensive rats (SHR) during embryonic development. METHODS: The study comprised the 2 following groups of SHR (n=5 each): treated group - rats conceived from SHR females treated with enalapril maleate (15 mg. kg-1.day-1) during gestation; and nontreated group - offspring of nontreated females. The newborns were euthanized within the first 24 hours after birth and their hearts were removed and processed for histological study. Three fields per animal were considered for computer-assisted digital analysis and determination of the volume densities (Vv) of the nuclei and CM. The images were segmented with the aid of Image Pro Plus® 4.5.029 software (Media Cybernetics). RESULTS: No difference was observed between the treated and nontreated groups in regard to body mass, cardiac mass, and the relation between cardiac and body mass. A significant reduction in the Vv[matrix] and a concomitant increase in the Vv[nuclei] were observed in the treated group as compared with those in the nontreated group. CONCLUSION: The treatment with enalapril of hypertensive rats during pregnancy alters the collagen content and structure of the myocardium of newborns

Análise da prevalência dos potenciais tardios ventriculares na fase tardia pós-infarto do miocárdio baseada na localização do infarto / 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

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