Velocity tracking of cardiac vector loops to identify signs of stress-induced ischaemia.

Coronary artery disease (CAD) is among the leading causes of death worldwide. Initial studies require an electrocardiogram stress test often followed by cardiac imaging procedures. However, conventional indices still show insufficient diagnostic performance. We propose quaternion methods to evaluate abnormal alterations during ventricular depolarization and repolarization. Assessment was conducted during a Bruce protocol treadmill stress test and after the end of the exercise. We developed an algorithm to automatically determine the beginning and end of exercise and then, computed the angular and linear velocities. Statistical analysis for feature selection and classification between ischaemic and non-ischaemic patients was used. The most significant markers were maximum linear velocity during ventricular depolarization (p < 5E-9) and maximum angular velocity during the second half of the repolarization loop (p < 5E-16). The latter reached sensitivity / specificity pair of 78 / 92 (AUC 0.89). A linear classifier showed a trend of reduction in cardiac vector velocity in at-risk patients after the end of exercise. The sensitivity / specificity pair reached was 86 / 100. Trajectory deviations of depolarization / repolarization loops that result from ischaemia effects, could be responsible for the observed reduction in dynamic changes during exercise. Further studies could provide non-invasive complementary tools to detect CAD risk. Graphical abstract This data is mandatory, please provide.

Wearable technology for electrocardiogram and vectocardiogram using the Dower Transformation / Tecnologia vestível para exames de eletrocardiograma e vetocardiograma utilizando a transformada de Dower / Tecnología vestible para exámenes de electrocardiograma y vetocardiograma utilizando de la transformada de Dower

Objectives: Thousands of people suffer from cardiovascular diseases. Even though the electrocardiogram is an exam consolidated. The lack of methodological observation in the placement of sensors can compromise the results. This article proposes a wearable vest capable of conditioning cardiac signals from three simultaneous channels, reducing the chance of failures in the exam due to the smaller number of electrodes attached to the patient's body. Methods: It adds the vectorcardiogram technique to the electrocardiogram wearable, which consists of three orthonormal derivations Vx, Vy, and Vz, measuring dynamic components of the heart vector. Results: The display of the cardiac biopotential in the web-mobile application represents the visualization of the twelve derivations synthesized from the Dower transform and the spatial projections of the cardiac loop under a three-dimensional view. Conclusion: Feasibility of integrating the vectorcardiogram with the electrocardiogram exam.

Objetivos: Milhares de pessoas sofrem com doenças cardiovasculares, apesar do Eletrocardiograma ser um exame consolidado, a falta de observação metodológica na colocação dos sensores pode comprometer os resultados. O presente artigo propõe um colete vestível capaz de condicionar sinais cardíacos de três canais simultâneos, reduzindo a chance de falhas na execução do exame em função da menor quantidade de eletrodos fixados ao corpo do paciente. Métodos: Acrescenta a técnica do vetocardiograma ao vestível de eletrocardiograma, que consiste em três derivações ortonormais Vx, Vy e Vz, medindo componentes dinâmicos do vetor coração. Resultados: Exibição do biopotencial cardíaco na aplicação web-mobile representa de forma satisfatória a visualização das doze derivações sintetizadas a partir da transformada de Dower, bem como, as projeções espaciais do loop cardíaco sob uma visão tridimensional. Conclusão: Viabilidade de integração do vetocardiograma ao exame de eletrocardiograma.

Objetivos: Miles de personas padecen enfermedades cardiovasculares, a pesar de que el electrocardiograma es un examen consolidado, la falta de observación metodológica en la colocación de sensores puede comprometer los resultados. Este artículo propone una tecnología vestible capaz de acondicionar las señales cardíacas de tres canales simultáneos, reduciendo la posibilidad de fallas en el examen por la menor cantidad de electrodos adheridos al cuerpo del paciente. Métodos: Agrega la técnica del vetocardiograma al electrocardiograma vestible, que consta de tres derivaciones ortonormales Vx, Vy y Vz, midiendo los componentes dinámicos del vector cardíaco. Resultados: La visualización del biopotencial cardíaco en la aplicación web-móvil representa satisfactoriamente la visualización de las doce derivaciones sintetizadas a partir de la transformada de Dower, así como las proyecciones espaciales del bucle cardíaco bajo una vista tridimensional. Conclusión: Viabilidad de integrar el vetocardiograma con el examen electrocardiográfico.

The Vectorcardiogram and the Main Dromotropic Disturbances.

Until the mid-1980s, it was believed that the vectorcardiogram (VCG) presented a greater specificity, sensitivity and accuracy in comparison to the 12-lead electrocardiogram (ECG), in the cardiology diagnosis. Currently, the VCG still is superior to the ECG in specific situations, such as in the evaluation of myocardial infarctions when associated with intraventricular conduction disturbances, in the identification and location of accessory pathways in ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, Brugada phenocopies, concealed form of arrhythmogenic right ventricular cardiomyopathy and zonal or fascicular blocks of the right bundle branch on right ventricular free wall.VCG allows us to analyze the presence of left septal fascicular block more accurately than ECG and in the diagnosis of the interatrial blocks and severity of some chambers enlargements. The three-dimensional spatial orientation of both the atrial and the ventricular activity provides a far more complete observation tool than the linear ECG. We believe that the ECG/VCG binomial simultaneously obtained by the technique called electro-vectorcardiography (ECG/VCG) brought a significant gain for the differential diagnosis of several pathologies. Finally, in the field of education and research, VCG provided a better and more rational tridimensional insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography.

Electro-vectorcardiographic and electrophysiological aspects of Ebstein's anomaly.

Ebstein's anomaly is a congenital heart disease where the most important anatomic feature is the inferior displacement of the tricuspid valve leaflets. Vectorcardiographic features are mainly forgotten and electrocardiographic features may be unrecognized by cardiologists handling adult patients.

Value of electro-vectorcardiogram in hypertrophic cardiomyopathy.

The electrocardiogram is an important tool for the initial diagnostic suspicion of hypertrophic cardiomyopathy in any of its forms, both in symptomatic and in asymptomatic patients because it is altered in more than 90 percent of the cases. Electrocardiographic anomalies are more common in patients carriers of manifest hypertrophic cardiomyopathy and the electrocardiogram alterations are earlier and more sensitive than the increase in left ventricular wall thickness detected by the echocardiogram. Nevertheless, despite being the leading cause of sudden death among young competitive athletes there is no consensus over the need to include the method in the pre-participation screening. In apical hypertrophic cardiomyopathy the electrocardiographic hallmarks are the giant negative T waves in anterior precordial leads. In the vectorcardiogram, the QRS loop is located predominantly in the left anterior quadrant and T loop in the opposite right posterior quadrant, which justifies the deeply negative T waves recorded. The method allows estimating the left ventricular mass because it relates to the maximal spatial vector voltage of the left ventricle in the QRS loop. The recording on electrocardiogram or Holter monitoring of nonsustained monomorphic ventricular tachycardia in patients with syncope, recurrent syncope in young patient, hypotension induced by strain, bradyarrhythmia, or concealed conduction are markers of poor prognosis. The presence of rare sustained ventricular tachycardia is observed in mid-septal obstructive HCM with apical aneurysm. The presence of complete right bundle branch block pattern is frequent after the percutaneous treatment and complete left bundle branch block is the rule after myectomy.