Eduardo Correa Barbosa

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.

Assessing autonomic function in hypertrophic cardiomyopathy

OBJECTIVE Assess the autonomic function in hypertrophic cardiomyopathy (HCM) through heart rate variability (HRV) and to correlate it to echocardiographic data. METHODS Two groups were studied, and compared for gender, age and HR: A) Ten (10) patients reporting septal HCM (70% non-obstructive); B) Ten (10) healthy volunteers. HRV was analyzed along four successive stages: at rest, under controlled breathing, while bending, and controlled breathing associated to bending. Variables means were compared between groups and intra-groups in the different stages; in Group A, variables means were correlated to echocardiographic measurements (interventricular septum and left atrial diameter). RESULTS No HRV difference was reported among groups in the first 3 stages. In the fourth stage vagal activity was shown to be higher in Group A [quadratic mean log between RR intervals (RMSSD) - 1.35+/-0.14 vs 1.17+/-0.16; p=0.019; high frequency component logarithm (LogHF)- 4.89+/-0.22 vs 4.62+/-0.26; p=0.032]. Along the stages, vagal measurements [rate of pairs of consecutive RR intervals whose difference is > or =50 ms (pNN50) and LogHF] also showed lower reduction in the third stage in Group A, while LogHF showed some increase in last stage (p=0.027), thus indicating marked parasympathetic activity in that group. Group A HRV analysis showed no difference among patients reporting larger hypertrophy or atrial diameter. CONCLUSION 1) Parasympathetic prevalence was shown during autonomic stimulation in HCM patients; 2) No correlation was found between HRV and echocardiographic measurements under analysis.

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

PURPOSE: To evaluate the diagnostic accuracy of monomorphic ventricular tachycardia (MVT), in patients with structural heart diseases and episodes of sustained MVT, using the signal-averaged ECG (SAECG) in the time (TD) and the frequency domain (FD) with statistical techniques of spectral correlation. METHODS: Twenty seven patients with at least one episode of sustained MVT, 30 patients with structural heart diseases and no evidence of ventricular arrhythmias and 80 subjects with no evidence of heart disease have been studied. SAECG was performed in all patients with the following parameters: duration of the filtered QRS, RMS 40 and LAS40 in TD and the mean and the standard deviation of both signal energy intersegmentar spectral correlation and energy frequency edge track in FD. RESULTS: The sensitivity(S) and positive predict value (PPV) of the SAECG in TD, in FD and combined analysis of both domains were: S = 59.3%, 63.0%, 81.5% and PPV = 80.0%, 81.0%, 84.6%, respectively. CONCLUSION: The combined analysis of SAECG in TD and in FD improves the diagnostic accuracy in patients with S sustained MVT.PURPOSE To evaluate the diagnostic accuracy of monomorphic ventricular tachycardia (MVT), in patients with structural heart diseases and episodes of sustained MVT, using the signal-averaged ECG (SAECG) in the time (TD) and the frequency domain (FD) with statistical techniques of spectral correlation. METHODS Twenty seven patients with at least one episode of sustained MVT, 30 patients with structural heart diseases and no evidence of ventricular arrhythmias and 80 subjects with no evidence of heart disease have been studied. SAECG was performed in all patients with the following parameters: duration of the filtered QRS, RMS 40 and LAS40 in TD and the mean and the standard deviation of both signal energy intersegmentar spectral correlation and energy frequency edge track in FD. RESULTS The sensitivity(S) and positive predict value (PPV) of the SAECG in TD, in FD and combined analysis of both domains were: S = 59.3%, 63.0%, 81.5% and PPV = 80.0%, 81.0%, 84.6%, respectively. CONCLUSION The combined analysis of SAECG in TD and in FD improves the diagnostic accuracy in patients with S sustained MVT.

Utility of a novel risk score for prediction of ventricular tachycardia and cardiac death in chronic Chagas disease - the SEARCH-RIO study

The SEARCH-RIO study prospectively investigated electrocardiogram (ECG)-derived variables in chronic Chagas disease (CCD) as predictors of cardiac death and new onset ventricular tachycardia (VT). Cardiac arrhythmia is a major cause of death in CCD, and electrical markers may play a significant role in risk stratification. One hundred clinically stable outpatients with CCD were enrolled in this study. They initially underwent a 12-lead resting ECG, signal-averaged ECG, and 24-h ambulatory ECG. Abnormal Q-waves, filtered QRS duration, intraventricular electrical transients (IVET), 24-h standard deviation of normal RR intervals (SDNN), and VT were assessed. Echocardiograms assessed left ventricular ejection fraction. Predictors of cardiac death and new onset VT were identified in a Cox proportional hazard model. During a mean follow-up of 95.3 months, 36 patients had adverse events: 22 new onset VT (mean±SD, 18.4±4‰/year) and 20 deaths (26.4±1.8‰/year). In multivariate analysis, only Q-wave (hazard ratio, HR=6.7; P<0.001), VT (HR=5.3; P<0.001), SDNN<100 ms (HR=4.0; P=0.006), and IVET+ (HR=3.0; P=0.04) were independent predictors of the composite endpoint of cardiac death and new onset VT. A prognostic score was developed by weighting points proportional to beta coefficients and summing-up: Q-wave=2; VT=2; SDNN<100 ms=1; IVET+=1. Receiver operating characteristic curve analysis optimized the cutoff value at >1. In 10,000 bootstraps, the C-statistic of this novel score was non-inferior to a previously validated (Rassi) score (0.89±0.03 and 0.80±0.05, respectively; test for non-inferiority: P<0.001). In CCD, surface ECG-derived variables are predictors of cardiac death and new onset VT.

I posicionamento brasileiro em hipertensão arterial e diabetes mellitus

The association between AH and DM was first described in the 70s, observed in both sexes and at any age range. The prevalence of hypertension is two to three-fold higher in diabetics than in the general population5, and about 70% of diabetics are hypertensive3,6. A meta-analysis of 102 prospective studies and 698,782 individuals showed that the presence of DM increases by two-fold the risk of coronary artery disease (CAD), cerebrovascular accident (CVA) and CV death. According to this meta-analysis, 10% of CV deaths in developed countries can be attributed to the presence of DM7.

Clinical assessment of the effect of digital filtering on the detection of ventricular late potentials

Ventricular late potentials are low-amplitude signals originating from damaged myocardium and detected on the body surface by ECG filtering and averaging. Digital filters present in commercial equipment may interfere with the ability of arrhythmia stratification. We compared 40-Hz BiSpec (BI) and classical 40- to 250-Hz band-pass Butterworth bidirectional (BD) filters in terms of impact on time domain variables and diagnostic properties. In a transverse retrospective age-adjusted case-control study, 221 subjects with sinus rhythm without bundle branch block were divided into three groups after signal-averaged ECG acquisition: GI (N = 40), clinically normal controls, GII (N = 158), subjects with coronary heart disease without sustained monomorphic ventricular tachycardia (SMVT), and GIII (N = 23), subjects with heart disease and documented SMVT. Conventional variables analyzed from vector magnitude data after averaging to 0.3 micro V final noise were obtained by application of each filter to the averaged signal, and evaluated in pairs by numerical comparison and by diagnostic agreement assessment, using conventional and optimized thresholds of normality. Significant differences were found between BI and BD variables in all groups, with diagnostic results showing significant disagreement between both filters [kappa value of 0.61 (P<0.05) for GII and 0.31 for GIII (P = NS)]. Sensitivity for SMVT was lower with BI than with BD (65.2 vs 91.3%, respectively, P<0.05). Filters provided significantly different numerical and diagnostic results and the BI filter showed only limited clinical application to risk stratification of ventricular arrhythmia.

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.

I Posicionamento Brasileiro sobre Pre-Hipertensao, Hipertensao do Avental Branco e Hipertensao Mascarada: Diagnostico e Conduta

Repeated BP measurement at the office allows the diagnosis of hypertension and normotension. To better assess BP behavior, there are methods that analyze BP by using a higher number of measurements, minimizing interferences of the environment, situation and observer. Those alternatives are as follows: 24-hour ambulatory BP monitoring (ABPM); and dwelling BP measurement [home BP monitoring (HBPM) and BP self-measurement (BPSM)]. Based on those methods, two other BP classifications were adopted: white coat hypertension (WCH) and masked hypertension (MH)1,3-5 (Figure 1).

Repolarização precoce no eletrocardiograma do atleta: bases iônicas e modelo vetorial

O padrao eletrocardiografico do atleta mimetiza variasalteracoes encontradas em diversas cardiopatias, fazendocom que, em um passado recente, tenham sido cometidascondutas equivocadas, como a pressuposicao da presencade cardiopatia e afastamento de esportistas de suas ativida-des. Esta revisao procura rever os mecanismos pelos quais oexercicio modifica a modulacao autonomica sobre o coracao epropoe explicacoes, baseadas em mecanismos eletrofisiolo-gicos e na teoria vetorial da ativacao cardiaca, para o padraoeletrocardiografico conhecido como repolarizacao precoce.

I Luso-Brazilian Positioning on Central Arterial Pressure

I Luso-Brazilian Positioning on Central Arterial Pressure Andréa A. Brandão,1 Celso Amodeo,1 Cristina Alcântara,2 Eduardo Barbosa,1 Fernando Nobre,1 Fernando Pinto,2 José Fernando Vilela-Martin,1 José Mesquita Bastos,2 Juan Carlos Yugar-Toledo,1 Marco Antônio Mota-Gomes, 1 Mario Fritsch Toros Neves, 1 Marcus Vinícius Bolívar Malachias,1 Manuel de Carvalho Rodrigues,2 Oswaldo Passarelli Junior,1 Paulo César B. Veiga Jardim,1 Pedro Guimarães Cunha,2 Rui Póvoa,1 Teresa Fonseca,2 Vitor Paixão Dias,2 Weimar Sebba Barroso,1 Wille Oigman1 Departamento de Hipertensão Arterial da Sociedade Brasileira de Cardiologia1, Rio de Janeiro, RJ – Brazil; Sociedade Portuguesa de HipertensãoPorto2 – Portugal