Comparison of spatial temporal representations of the vectorcardiogram using digital image processing

INTRODUCTION: The vectorcardiography (VCG) is a method of representing the heart's electrical activity in three dimensions that is not frequently used in clinical practice due to the higher complexity compared to electrocardiography (ECG). A way around this problem was the development of regression techniques to obtain the VCG from the 12 lead ECG and the evaluation of these techniques is done by comparing the parameters obtained by the gold standard method and by the VCG obtained by the alternative methods. In this paper it is proposed instead a comparison between the images of the VCG planes using the values returned by digital image processing metrics such as PSNR, SSIM and PW-SSIM. METHODS: The signals used were obtained from the Physikalisch-Technische Bundesanstalt Diagnostic ECG Database, which contains both the VCGs obtained by the gold standard method and the 12 lead ECG signals. They were divided into five groups that contained a control group and according to the region of the wall infarction. The ECG signals were then filtered using a Butterworth Finite Impulse Response bandpass filter, with cutoff frequencies of 3 Hz and 45 Hz and then the VCGs were by a computer application using the Kors inverse matrix method, the Kors quasi-orthogonal method and the Dower Inverse Matrix method. The reconstructed signals were then compared using the PSNR, SSIM and PW-SSIM methods. The returned values were presented in tables for each group containing the average value and standard deviance for each method in each VCG plane. RESULTS: Using image processing techniques, it was possible to perceive that the alternative methods to obtain the VCG have a high confiability that could be compared to the gold standard in signals from healthy subjects. However, signals from pathological subjects present variations that could be caused by a deficit of these alternative methods to represent the pathology in these cases. Considering the PW-SSIM, the frontal plane by the reconstructions was considered the most similar to the gold standard, having PW-SSIM values higher than 0.93 and for the horizontal plane two groups had PW-SSIM values lower than 0.90 and for the Sagittal plane all groups had values lower than this value. DISCUSSION: The values yielded by the PSNR and SSIM had low variance, worsening the perception of the effect of the reconstruction method used or the infarction effect over the reconstruction. The values lower than 0.90 could indicate that these planes have their generation most affected by the infarction. CONCLUSION: The three methods of obtaining the VCG Frank leads, the Kors Quasi-Orthogonal method, the Kors Linear Regression method and the Dower Inverse Matrix, presented differences in the metrics: PSNR, SSIM and PW-SSIM in normal subjects according to the planes frontal, horizontal and sagittal and in subjects with Myocardial Infarction according to its topography: anterior, inferolateral, inferior or multiarterials. Considering only the PW-SSIM, the QO method had the best performance in different signals, followed by the Dower method. (AU)

Advanced ECG in 2016: is there more than just a tracing?

The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology. It is critical for evidence-based management of patients with most cardiovascular conditions, including patients with acute myocardial infarction, suspected chronic cardiac ischaemia, cardiac arrhythmias, heart failure and implantable cardiac devices. In contrast to many other techniques in cardiology, the ECG is simple, small, mobile, universally available and cheap, and therefore particularly attractive. Standard ECG interpretation mainly relies on direct visual assessment. The progress in biomedical computing and signal processing, and the available computational power offer fascinating new options for ECG analysis relevant to all fields of cardiology. Several digital ECG markers and advanced ECG technologies have shown promise in preliminary studies. This article reviews promising novel surface ECG technologies in three different fields. (1) For the detection of myocardial ischaemia and infarction, QRS morphology feature analysis, the analysis of high frequency QRS components (HF-QRS) and methods using vectorcardiography as well as ECG imaging are discussed. (2) For the identification and management of patients with cardiac arrhythmias, methods of advanced P-wave analysis are discussed and the concept of ECG imaging for noninvasive localisation of cardiac arrhythmias is presented. (3) For risk stratification of sudden cardiac death and the selection of patients for medical device therapy, several novel markers including an automated QRS-score for scar quantification, the QRS-T angle or the T-wave peak-to-end-interval are discussed. Despite the existing preliminary data, none of the advanced ECG markers and technologies has yet accomplished the transition into clinical practice. Further refinement of these technologies and broader validation in large unselected patient cohorts are the critical next step needed to facilitate translation of advanced ECG technologies into clinical cardiology.

Vectorcardiographic diagnostic & prognostic information derived from the 12-lead electrocardiogram: Historical review and clinical perspective.

In the course of time, electrocardiography has assumed several modalities with varying electrode numbers, electrode positions and lead systems. 12-lead electrocardiography and 3-lead vectorcardiography have become particularly popular. These modalities developed in parallel through the mid-twentieth century. In the same time interval, the physical concepts underlying electrocardiography were defined and worked out. In particular, the vector concept (heart vector, lead vector, volume conductor) appeared to be essential to understanding the manifestations of electrical heart activity, both in the 12-lead electrocardiogram (ECG) and in the 3-lead vectorcardiogram (VCG). Not universally appreciated in the clinic, the vectorcardiogram, and with it the vector concept, went out of use. A revival of vectorcardiography started in the 90's, when VCGs were mathematically synthesized from standard 12-lead ECGs. This facilitated combined electrocardiography and vectorcardiography without the need for a special recording system. This paper gives an overview of these historical developments, elaborates on the vector concept and seeks to define where VCG analysis/interpretation can add diagnostic/prognostic value to conventional 12-lead ECG analysis.

12-lead Holter electrocardiography. Review of the literature and clinical application update.

This brief review is focused on 12-lead Holter electrocardiogram (ECG) recording including a review of the literature and the description of the advantages of its application. The standard 12-lead ECG provides a bedside snapshot of the electrical activity of the heart including vector information, but a snapshot of a few beats for some seconds might miss the whole story. Traditional Holter ECG displaying two or three leads may record all heart beats during a prolonged period, but the limited vector information might be a cause of shortcomings in the ECG diagnosis. The 12-lead Holter ECG overcomes these disadvantages and should be preferred for detecting episodes of arrhythmias, localize their origin or the localization of myocardial ischemia. The 12-lead Holter ECG monitoring is efficient in the evaluation of the effect of drugs or interventional therapeutic procedures, i.e., efficiency of biventricular pacing in patients with heart failure and permanent atrial fibrillation (AF). The automatic analysis of parameters in 12-lead Holter ECG is also providing information for risk stratification. In order to obtain a precise diagnosis based on the criteria established on standard ECG, the "real" 12-lead ECG with ten electrodes is advocated.

Significance of vectorcardiogram in the cardiological diagnosis of the 21st century.

Until the mid-1980s, it was believed that the vectorcardiogram presented a greater specificity, sensitivity and accuracy in comparison to the conventional electrocardiogram, in the diagnosis of the different heart diseases. Recent studies revealed that the vectorcardiogram still is superior to the electrocardiogram in very specific situations, such as in the evaluation of electrically inactive areas, in intraventricular conduction disorders combined and/or in association to inactive areas, in the identification and location of ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, and in the estimation of the severity of some enlargements, among others. With the advent of computerized vectorcardiography, a technology that improves the processing and recording method; a future still promising is expected for this methodology. In the fields of education and research, vectorcardiography provided a better and more rational insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography. Although a few medical centers still use the method as a routine, we hope that the use of this resource will not get lost over time, since vectorcardiography still represents a source to enrich science by enabling a better morphological interpretation of the electrical phenomena of the heart.

[Spatial vector electrocardiography: technique, perspectives of use]. / Prostranstvennaia vektorélektrokardiografiia.

Potentials of the use of computer synthesis of integral electrical vector of the heart D0 are described. Calculation of spatial angular vector velocity and linear velocity of its movement along trajectory can be carried out in a framework of biophysical dipole model. Spatial presentation of vector is realized and its behavior in accordance with established pathologies discussed. Possible diagnostic value of obtained results and utility of their introduction into clinical practice are stressed.

Historia y perspectivas de la exploración electrovectocardiográfica / History and perspectives of electro-vectocardiography examination

Se presenta una panorámica del desarrollo de la electrovectocardiogragía desde la construcción del primer electrocardiógrafo con galvanómetro de cuerda por Einthoven a principios de este siglo, hasta nuestros días. Se hace hincapié en la esencia funcional de este tipo de exploración cardíaca y se subrayan las etapas fundamentales de su evolución: las derivaciones bipolares en sus comienzos,, las unipolares alejadas y el inicio de la vectocardiografía en la década de los 30, las unipolares próximas en la década de los 40, los electrogramas hisianos y las cartografías intracavitarias y de superficie en la década de los 60 y, despúes, las grabaciones continuas en cinta magnética. Se describe asimismo la evolución desde el eletrocardiógrafo primitivo de Einthoven hasta los modernos de inscripción directa y los oscilógrafos de rayos catódicos. Se relatan, en fin, las contribuciones de la Escuela Mexicana a la interpretación racional de los registros electrovectocardiográficos y al esclarecimiento de algunos aspectos de la eletrofisiopatología del miocardio

Historia y perspectivas de la exploración electrovectocardiográfica / History and perspectives of electro-vectocardiography examination

Se presenta una panorámica del desarrollo de la electrovectocardiogragía desde la construcción del primer electrocardiógrafo con galvanómetro de cuerda por Einthoven a principios de este siglo, hasta nuestros días. Se hace hincapié en la esencia funcional de este tipo de exploración cardíaca y se subrayan las etapas fundamentales de su evolución: las derivaciones bipolares en sus comienzos,, las unipolares alejadas y el inicio de la vectocardiografía en la década de los 30, las unipolares próximas en la década de los 40, los electrogramas hisianos y las cartografías intracavitarias y de superficie en la década de los 60 y, despúes, las grabaciones continuas en cinta magnética. Se describe asimismo la evolución desde el eletrocardiógrafo primitivo de Einthoven hasta los modernos de inscripción directa y los oscilógrafos de rayos catódicos. Se relatan, en fin, las contribuciones de la Escuela Mexicana a la interpretación racional de los registros electrovectocardiográficos y al esclarecimiento de algunos aspectos de la eletrofisiopatología del miocardio (AU)