Carlos Roberto Martins Rodrigues Sobrinho

An innovative approach of QRS segmentation based on first-derivative, Hilbert and Wavelet Transforms

The QRS detection and segmentation processes constitute the first stages of a greater process, e.g., electrocardiogram (ECG) feature extraction. Their accuracy is a prerequisite to a satisfactory performance of the P and T wave segmentation, and also to the reliability of the heart rate variability analysis. This work presents an innovative approach of QRS detection and segmentation and the detailed results of the proposed algorithm based on First-Derivative, Hilbert and Wavelet Transforms, adaptive threshold and an approach of surface indicator. The method combines the adaptive threshold, Hilbert and Wavelet Transforms techniques, avoiding the whole ECG signal preprocessing. After each QRS detection, the computation of an indicator related to the area covered by the QRS complex envelope provides the detection of the QRS onset and offset. The QRS detection proposed technique is evaluated based on the well-known MIT-BIH Arrhythmia and QT databases, obtaining the average sensitivity of 99.15% and the positive predictability of 99.18% for the first database, and 99.75% and 99.65%, respectively, for the second one. The QRS segmentation approach is evaluated on the annotated QT database with the average segmentation errors of 2.85±9.90ms and 2.83±12.26ms for QRS onset and offset, respectively. Those results demonstrate the accuracy of the developed algorithm for a wide variety of QRS morphology and the adaptation of the algorithm parameters to the existing QRS morphological variations within a single record.

Endocardite infecciosa valvar submetida a tratamento cirúrgico: análise de 64 casos

OBJECTIVE: To identify some aspects of the infective valve endocarditis treated by heart surgery, as well as antibiotic therapy, in a public hospital, in the city of Fortaleza, Ceara state, Brazil, from1988 to 2003. METHOD: A retrospective and observational study of 64 patients with Infective Valve Endocarditis who required aortic and/or mitral valve replacement, tricuspid vegectomy and repair or pulmonary valve valvulectomy, as well as antibiotic therapy, during their in-hospital stay. They were analyzed in respect to gender, age, time elapsed from hospital admission to the surgery, time elapsed from hospital admission to hospital discharge, valve lesion, blood culture result, surgical treatment and mortality. RESULTS: Infective valve endocarditis treated with heart surgery was more frequent in the third decade of life. Most of patients (81.2%) were males. The patients who died spent a shorter time from hospital admission to the surgery than the patients who survived. The aortic valve was affected in 65% of cases. Positivity blood culture were seen in 42% and Staphylococcus aureus was isolated in 52.4% of these cases. Valve replacement was necessary in 93.7% of cases. The in-hospital mortality rate was 14.1% which was not influenced by the age of the patient or the blood culture result. CONCLUSION: Infective valve endocarditis treated by heart surgery was more frequent in men and in the third decade of life. It mostly affected the aortic valve. Staphylococcus aureus was the more common pathogen found. Almost all the patients needed replacement of the infected valve and the in-hospital mortality rate was 14.1%.

Long-Term Follow-Up of Patients with Chronic Chagas Disease and Implantable Cardioverter-Defibrillator

Chronic Chagas heart disease (ChHD) is associated with ventricular tachyarrhythmias and an increased risk of sudden cardiac death. Little is known about the effectiveness of implantable cardioverter‐defibrillator (ICD) therapy in this population. The objective of this study was to evaluate the efficacy of ICD in patients with ChHD and to identify predictors of mortality and appropriate ICD shocks.

Cardiac tumours: clinical, echocardiographic and pathological features

OBJETIVO: Caracterizacao clinica e ecocardiografica dos pacientes com tumores cardiacos, avaliacao da terapeutica cirurgica e da recidiva dos tumores. METODO: Na primeira parte da pesquisa, o delineamento metodologico foi do tipo retrospectivo, atraves da identificacao de tumores cardiacos e coleta de dados dos prontuarios do Hospital Universitario Walter Cantidio (UFCE) e Hospital de Messejana, no periodo de 1981 a 2001, onde foram encontrados 19 casos de tumores cardiacos. Os pacientes foram submetidos a uma reavaliacao clinica, eletro e ecocardiografica durante o periodo de marco a julho de 2002. RESULTADOS: Sintomas congestivos e dor toracica foram os sintomas mais frequentes em nossa serie. A localizacao preferencial dos tumores cardiacos em nossa serie foi no atrio esquerdo. Entre os pacientes submetidos a operacao, todos tiveram o tumor ressecado dos atrios, predominando a localizacao em atrio esquerdo (79%). O tipo histopatologico mais encontrado em nossa serie foi o mixoma (78%). A mortalidade cirurgica foi de 14%. Detectamos recidiva de tumor em um paciente. CONCLUSOES: Tumores cardiacos foram mais encontrados no atrio esquerdo. Os tumores benignos foram mais frequentes que os malignos. O tipo histopatologico mais encontrado foi o mixoma.

Programa de educação em reanimação cardiorrespiratória: ensinando a salvar vidas

Cardiac arrest is the biggest cause of death in the world. There is a lack of adequate training of the public in how to act effectively in these situations and thus increase the victims chances of survival. Therefore, the Cardiopulmonary Resuscitation Education Program (PERC) was created in 1996 with the principal aim of promoting knowledge about CPR by training laymen, health students and professionals in the Brazilian state of Ceara. Over the course of sixteen years, roughly 8,000 people have been trained directly by the PERC. However, it is hard to gauge the full extent of the benefits of this program due to the unlimited, chain diffusion of knowledge from person to person. Thanks to the experience acquired by PERC in CPR, it has been possible to confirm the level ignorance about the issue among the Ceara public. However, following the American Heart Association (AHA) guidelines released every five years, the program is raising awareness about the importance of resuscitation, training people to act satisfactorily when faced with a cardiac arrest situation.

Clinical Course After Cardioverter-Defibrillator Implantation: Chagasic Versus Ischemic Patients

Background: The outcome of Chagas disease patients after receiving implantable cardioverter defibrillator (ICD) is still controversial. Objective: To compare clinical outcomes after ICD implantation in patients with chronic Chagas cardiomyopathy (CCC) and ischemic heart disease (IHD). Methods: Prospective study of a population of 153 patients receiving ICD (65 with CCC and 88 with IHD). The devices were implanted between 2003 and 2011. Survival rates and event-free survival were compared. Results: The groups were similar regarding sex, functional class and ejection fraction. Ischemic patients were, on average, 10 years older than CCC patients (p < 0.05). Patients with CCC had lower schooling and monthly income than IHD patients (p < 0.05). The number of appropriate therapies was 2.07 higher in CCC patients, who had a greater incidence of appropriate shock (p < 0.05). Annual mortality rate and electrical storm incidence were similar in both groups. There was no sudden death in CCC patients, and only one in IHD patients. Neither survival time (p = 0.720) nor event-free survival (p = 0.143) significantly differed between the groups. Conclusion: CCC doubles the risk of receiving appropriate therapies as compared to IHD, showing the greater complexity of arrhythmias in Chagas patients.

Dosagem de microalbuminúria em hipertensos e em pacientes portadores de doença coronariana

BACKGROUND The normal 24-hour albumin excretion rate is of 20 mg. A persistent rate of 30 to 300 mg/day is called microalbuminuria and is related to a higher prevalence of cardiovascular disease. OBJECTIVE 1) To determine the prevalence of microalbuminuria in a group of hypertensive patients and in a group of patients with coronary artery disease; 2) To determine the relationship between the presence of microalbuminuria and hypertension, diabetes mellitus, dyslipidemia, smoking and obesity. METHODS The presence of microalbuminuria in a group of hypertensive patients (73 individuals) and in a group of patients with coronary artery disease (39 individuals) was determined and compared with a control group (43 individuals). Microalbuminuria was defined as an albumin/creatinine ratio higher than 30 and lower than 300 in a spot morning urine sample. The chi-square test and the Fishers exact test were used in the statistical analysis. RESULTS Microalbuminuria was present in 9.5% of the hypertensive individuals and in 33% of the patients with coronary artery disease, and was absent in individuals of the control group. When the occurrence of microalbuminuria was analyzed according to the different clinical parameters, regardless of the group involved, a statistically significant correlation was found with age, diabetes and dyslipidemia. CONCLUSION 1) The prevalence of microalbuminuria in hypertensive individuals is high, and is even higher in patients with coronary artery disease; 2) There is a correlation of the presence of microalbuminuria with age, diabetes and dyslipidemia.

Who Are the Super-Responders to Cardiac Resynchronization Therapy?

Fundamento: Pacientes submetidos a ressincronizacao cardiaca podem evoluir com padroes de resposta acima do esperado, com normalizacao dos parâmetros clinicos e ecocardiograficos. Objetivo: Analisar as caracteristicas clinicas e ecocardiograficas desta populacao de super-respondedores, comparando-as com os demais pacientes submetidos a terapia de ressincronizacao cardiaca. Metodos: Estudo de coorte observacional, prospectivo, envolvendo 146 pacientes, consecutivamente submetidos a implantes de ressincronizador cardiaco. Para comparacao das variaveis, foram realizados o teste exato de Fisher e o teste de Mann-Whitney. Foram considerados super-respondedores os pacientes com fracao de ejecao > 50 % e classe funcional I/II (New York Heart Association) apos 6 meses da terapia de ressincronizacao cardiaca. Resultados: A idade media foi de 64,8 ± 11,1 anos, sendo 69,8% do sexo masculino, com mediana da fracao de ejecao de 29%, sendo 71,5% com bloqueio de ramo esquerdo, 12% com bloqueio de ramo direito associado a bloqueios divisionais; 16,3% com marca-passo cardiaco definitivo, 29,3% com miocardiopatia isquemica, 59,4% com miocardiopatia dilatada e 11,2% com miocardiopatia chagasica. Foram observados 24 (16,4%) super-respondedores, sendo que 13 (8,9%) apresentaram normalizacao da fracao de ejecao, dos diâmetros diastolicos do ventriculo esquerdo e da classe funcional. Quando comparados com os pacientes nao super-respondedores, em relacao as caracteristicas pre-implante, os super-respondedores apresentaram-se mais no sexo feminino (58,3% vs. 22,8%; p = 0,002), maior indice de massa corporal (26,8 vs. 25,5; p = 0,013), maior fracao de ejecao basal (31,0 vs. 26,9; p = 0,0003) e menores diâmetros diastolicos do ventriculo esquerdo (65,9 mm vs. 72,6 mm; p = 0,0032). Dez pacientes (41,6% dos super-respondedores) com bloqueio de ramo direito e bloqueio divisional evoluiram como super-respondedores, entretanto apenas um paciente com doenca de Chagas e apenas na primeira avaliacao. Conclusoes: Os super-respondedores apresentaram cardiopatia de base menos avancada e sem diferencas em relacao ao tipo de disturbio de conducao basal. Pacientes com bloqueio de ramo direito e bloqueio divisional, mas sem cardiopatia chagasica podem tambem evoluir como super-respondedores.

Development and Validation of Predictive Models of Cardiac Mortality and Transplantation in Resynchronization Therapy

Background 30-40% of cardiac resynchronization therapy cases do not achieve favorable outcomes. Objective This study aimed to develop predictive models for the combined endpoint of cardiac death and transplantation (Tx) at different stages of cardiac resynchronization therapy (CRT). Methods Prospective observational study of 116 patients aged 64.8 ± 11.1 years, 68.1% of whom had functional class (FC) III and 31.9% had ambulatory class IV. Clinical, electrocardiographic and echocardiographic variables were assessed by using Cox regression and Kaplan-Meier curves. Results The cardiac mortality/Tx rate was 16.3% during the follow-up period of 34.0 ± 17.9 months. Prior to implantation, right ventricular dysfunction (RVD), ejection fraction < 25% and use of high doses of diuretics (HDD) increased the risk of cardiac death and Tx by 3.9-, 4.8-, and 5.9-fold, respectively. In the first year after CRT, RVD, HDD and hospitalization due to congestive heart failure increased the risk of death at hazard ratios of 3.5, 5.3, and 12.5, respectively. In the second year after CRT, RVD and FC III/IV were significant risk factors of mortality in the multivariate Cox model. The accuracy rates of the models were 84.6% at preimplantation, 93% in the first year after CRT, and 90.5% in the second year after CRT. The models were validated by bootstrapping. Conclusion We developed predictive models of cardiac death and Tx at different stages of CRT based on the analysis of simple and easily obtainable clinical and echocardiographic variables. The models showed good accuracy and adjustment, were validated internally, and are useful in the selection, monitoring and counseling of patients indicated for CRT.

Echocardiographic Predictors of Worse Outcome After Cardiac Resynchronization Therapy

Background Cardiac resynchronization therapy (CRT) is the recommended treatment by leading global guidelines. However, 30%-40% of selected patients are non-responders. Objective To develop an echocardiographic model to predict cardiac death or transplantation (Tx) 1 year after CRT. Method Observational, prospective study, with the inclusion of 116 patients, aged 64.89 ± 11.18 years, 69.8% male, 68,1% in NYHA FC III and 31,9% in FC IV, 71.55% with left bundle-branch block, and median ejection fraction (EF) of 29%. Evaluations were made in the pre-implantation period and 6-12 months after that, and correlated with cardiac mortality/Tx at the end of follow-up. Cox and logistic regression analyses were performed with ROC and Kaplan-Meier curves. The model was internally validated by bootstrapping. Results There were 29 (25%) deaths/Tx during follow-up of 34.09 ± 17.9 months. Cardiac mortality/Tx was 16.3%. In the multivariate Cox model, EF < 30%, grade III/IV diastolic dysfunction and grade III mitral regurgitation at 6-12 months were independently related to increased cardiac mortality or Tx, with hazard ratios of 3.1, 4.63 and 7.11, respectively. The area under the ROC curve was 0.78. Conclusion EF lower than 30%, severe diastolic dysfunction and severe mitral regurgitation indicate poor prognosis 1 year after CRT. The combination of two of those variables indicate the need for other treatment options.