Heartbeat classification system based on neural networks and dimensionality reduction

Abstract Introduction This paper presents a complete approach for the automatic classification of heartbeats to assist experts in the diagnosis of typical arrhythmias, such as right bundle branch block, left bundle branch block, premature ventricular beats, premature atrial beats and paced beats. Methods A pre-processing step was performed on the electrocardiograms (ECG) for baseline removal. Next, a QRS complex detection algorithm was implemented to detect the heartbeats, which contain the primary information that is employed in the classification approach. Next, ECG segmentation was performed, by which a set of features based on the RR interval and the beat waveform morphology were extracted from the ECG signal. The size of the feature vector was reduced by principal component analysis. Finally, the reduced feature vector was employed as the input to an artificial neural network. Results Our approach was tested on the Massachusetts Institute of Technology arrhythmia database. The classification performance on a test set of 18 ECG records of 30 min each achieved an accuracy of 96.97%, a sensitivity of 95.05%, a specificity of 90.88%, a positive predictive value of 95.11%, and a negative predictive value of 92.7%. Conclusion The proposed approach achieved high accuracy for classifying ECG heartbeats and could be used to assist cardiologists in telecardiology services. The main contribution of our classification strategy is in the feature selection step, which reduced classification complexity without major changes in the performance.

ECG-based detection of left ventricle hypertrophy

Introduction Left ventricle hypertrophy (LVH) is an important risk factor for cardiovascular morbidity and mortality. It is characterized by a thickening of the walls of the left ventricle. The transthoracic echocardiogram is a very accurate method for LVH detection. However, the electrocardiogram (ECG) offers an alternative method in diagnosing LVH, besides being less expensive and easier to obtain. In this context, this study proposes an ECG based approach for left ventricle hypertrophy (LVH) classification. Methods According to the literature, several indexes have so far been proposed that suggest specific changes in cardiac structure, however, generally speaking there is no consensus about the best criteria. This way, instead of considering only one LVH criterion, a score derived from electrocardiographic traces was employed which explores the complementarity of the best criteria through a fusion strategy. The best criteria are those which discriminate normal and LVH ECGs. Results The experiments were performed in the Monica database with a group of fifty men. Half of the individuals had LVH diagnosed by calculating the left ventricular mass index measured by transthoracic echocardiography. The score fusion proposed achieved a sensitivity of 78.3% and specificity of 91.3%, outperforming all isolated LVH criteria. Discussion Unlike the other methods, our score must be estimated within a computer because of its high complexity. Even with this limitation it is much less expensive than using the echocardiography.

Remoção Precoce do Introdutor Arterial Após Intervenção Coronária Percutânea por Via Femoral: Estudo de Segurança e Eficácia / Early Removal of the Arterial Sheath After Percutaneous Coronary Intervention Using the Femoral Approach: Safety and Efficacy Study

Introdução: Avaliamos a segurança e eficácia do uso de protamina, guiada pelo tempo de coagulação ativado, para a remoção imediata do introdutor arterial femoral em pacientes submetidos à intervenção coronária percutânea com heparina não fracionada, com o objetivo de propor um algoritmo para a prática clínica. Métodos: Estudo prospectivo, com pacientes consecutivos, com angina estável ou com síndrome coronariana aguda de baixo ou moderado risco. Comparamos os pacientes com a retirada precoce do introdutor arterial àqueles nos quais o introdutor foi retirado de acordo com o protocolo convencional. A decisão pela remoção precoce ou convencional do introdutor foi deixada a critério do operador. Resultados: O grupo de remoção precoce (n = 149) apresentou menor tempo de manuseio do sítio de punção que o grupo de remoção convencional (58,3 ± 21,4 minutos vs. 355 ± 62,9 minutos; p < 0,01), principalmente devido à redução do tempo até a retirada do introdutor (42,3 ± 21,1 minutos vs. 338,6 ± 61,5 minutos; p < 0,01), sem impacto sobre a duração da compressão femoral (16,0 ± 3,6 minutos vs. 16,4 ± 5,1 minutos; p = 0,49). Não houve trombose hospitalar de stent e nem diferença significativa na incidência de eventos vasculares ou hemorrágicos. A incidência de outras hemorragias, que levaram à hospitalização prolongada, foi menor no grupo de remoção precoce (1,3% vs. 5,1%; p = 0,05). Conclusões: O uso seletivo de uma abordagem, para a remoção imediata do introdutor femoral guiada pelo tempo de coagulação ativado e a administração de protamina, é seguro e eficaz em pacientes submetidos à intervenção coronária...

Introduction: We evaluated the safety and efficacy of protamine administration, guided by activated clotting time, for the immediate femoral arterial sheath removal in patients undergoing percutaneous coronary intervention with unfractionated heparin in order to propose an algorithm for clinical practice. Methods: Prospective study with consecutive patients with stable angina or low-to-moderate risk acute coronary syndrome. We compared patients with an early removal of the arterial sheath to those whose sheath removal was based on a standard protocol. Results: The early removal group (n = 149) had lower access manipulation time than the conventional group (58.3 ± 21.4 minutes vs. 355.0 ± 62.9 minutes; p < 0.01), mainly due to a reduced time to sheath removal (42.3 ± 21.1 minutes vs. 338.6 ± 61.5 minutes; p < 0.01), with no impact on the duration of femoral compression (16.0 ± 3.6 minutes vs. 16.4 ± 5.1 minutes; p = 0.49). There was no stent thrombosis during hospitalization and no significant differences in the incidence of major vascular or bleeding events. The incidence of other bleeding events leading to a prolonged in-hospital length of stay was lower in the early removal group (1.3% vs. 5.1%; p = 0.05). Conclusions: The selective use of an approach for immediate femoral sheath removal, based on activated clotting time guidance and protamine administration, is a safe and effective option in patients undergoing percutaneous coronary intervention by femoral access...

Adequabilidade da transfusão de concentrado de hemácias em hospital terciário de Porto Alegre, RS / Adequacy of packed red blood cells transfusion in a tertiary hospital in Porto Alegre, RS

Introdução: A transfusão de concentrado de hemácias (CH) representa um dos possíveis tratamentos utilizados para restauração da oxigenação tecidual nas situações em que a demanda de oxigênio ultrapassa a oferta. Entretanto, o limiar a partir do qual a transfusão de CH estaria indicada é ainda controverso, resultando em parâmetro heterogêneo na prática médica. O presente trabalho objetiva verificar a adequabilidade da indicação de transfusão de CH em pacientes internados em um hospital terciário em Porto Alegre, RS. Métodos: Estudo transversal descritivo envolvendo pacientes adultos internados em enfermarias clínicas e cirúrgicas durante período de 30 dias. Resultados: No período proposto foram prescritas 190 unidades de CH para total de 109 pacientes elegíveis. Cinquenta porcento dos pacientes transfundidos possuíam Hb<7g/dL, 26,7% entre 7-10 g/dL sem sintomas, 18,8% entre 7-10 g/dL com sintomas, 0,9% Hb>10 g/dL e 3,6% apresentaram quadro de hemorragia maciça previamente à transfusão, totalizando 28,5% de transfusões inadequadas. Conclusão: transfusão de CH é uma opção terapêutica em diversas situações clínicas e cirúrgicas, porém, a revisão da literatura evidencia que ainda não dispomos de valores bem estabelecidos para indicar ou não a transfusão de hemácias. O uso racional de hemoderivados acarretaria redução de riscos relacionados à transfusão, manutenção de estoques para situações de real necessidade, bem como diminuição de custos para o sistema de saúde.

Introduction: The transfusion of red blood cells is one of the possible treatments for restoration of tissue oxygenation in situations in which oxygen demand outstrips supply. However, the threshold at which red blood cells transfusion is indicated is still controversial, resulting in a heterogeneous parameter in medical practice. This study aims to assess the adequacy of the indication for red blood cells transfusion in patients admitted to a tertiary hospital in Porto Alegre, Brazil. Methods: A cross sectional study involving adult inpatients in medical and surgical wards over a period of 30 days. Results: During the studied period 190 units of packed red blood cells were prescribed for a total of 109 eligible patients. Fifty percent of the transfused patients had Hb<7g/dl, 26.7% around 710 g/dL without symptoms, 18.8% around 710 g/dL with symptoms, 0.9% Hb>10 g/dL and 3.6% had massive hemorrhage prior to transfusion, totaling 28.5% of inappropriate transfusions. Conclusion: CH transfusion is a treatment option in many clinical and surgical situations, but a literature review shows that as yet we do not have well-established values whether to indicate erythrocyte transfusions or not. The rational use of blood products would result in reduction of risks related to transfusion, maintaining stocks for situations of real need, as well as decreasing costs to the health system.

Síndrome de Wellens / Wellens syndrome

A avaliação de dor torácica é prática de rotina em serviços de emergência. Embora seja queixa comum e com amplo diagnóstico diferencial. é na suspeita de síndrome coronariana aguda (SCA) que a preocupação é maior. Eletrocardiograma e dosagem de enzimas cardíacas são ferramentas importantes na investigação dos pacientes. mas. quando negativos. podem não identificar algumas doenças. Relatamos o caso de uma paciente com angina. cujos exames iniciais na emergência não apresentavam alterações sugestivas de cardiopatia isquêmica. Doença de conhecimento recente. a síndrome de Wellens consiste em uma variante da angina instável. que. quando não reconhecida. pode acarretar em significativa morbidade e mortalidade.

The assessment of chest pain is a routine in emergency health services. Although this is a common complaint with a broad differential diagnosis. the major concern is the possibility of acute coronary syndrome (ACS). Electrocardiography and cardiac enzyme levels are important tools in the investigation of these patients; however. negative results may actually be overlooking the identification of some conditions. We report the case of a female patient with angina. whose baseline tests in the emergency room were negative for changes suggestive of ischemic heart disease. The Wellens syndrome. a recently described disease. is a variant of unstable angina which. if not identified. may result in significant morbidity and mortality.

Hematoma de músculo iliopsoas na vigência de tratamento com varfarina / Iliopsoas muscle hematoma during treatment with warfarin / Hematoma de músculo iliopsoas en la vigencia de tratamiento con warfarina

A varfarina é droga amplamente utilizada na prevenção de fenômenos tromboembólicos e o conhecimento de seus efeitos adversos faz-se necessário para o acompanhamento dos pacientes. Embora o desenvolvimento de discrasias sanguíneas seja complicação potencial nesses pacientes, a ocorrência de sangramento retroperitoneal é rara. Este artigo discute o caso de um paciente que evoluiu com hematoma do músculo iliopsoas durante tratamento com a referida droga, pós-implante de prótese aórtica metálica, com quadro clínico envolvendo importantes diagnósticos diferenciais.

Warfarin is a widely used drug for the prevention of thromboembolic events. Knowledge of its adverse effects is necessary for patient follow-up. Although the development of blood dyscrasias is a potential complication in these patients, retroperitoneal bleeding is rare. This article reports the case of a patient who developed iliopsoas muscle hematoma during treatment with warfarin after implantation of a metallic prosthetic aortic valve. The clinical manifestations involved important differential diagnoses.

La warfarina es un fármaco ampliamente utilizado en la prevención de fenómenos tromboembólicos, y el conocimiento de sus efectos adversos se hace necesario para el seguimiento de los pacientes. Aunque el desarrollo de discrasias sanguíneas es la complicación potencial en estos pacientes, la ocurrencia de sangrado retroperitoneal es rara. Este artículo discute el caso de un paciente que evolucionó con hematoma del músculo ileopsoas durante tratamiento con el referido fármaco en el postimplante de prótesis mitral metálica, con cuadro clínico implicando importantes diagnósticos diferenciales.