ABC | Volume 113, Nº1, July 2019

Review Article Applicability of the Electro-Vectorcardiogram in Current Clinical Practice Carlos Alberto Pastore , Nelson Samesima, Horacio Gomes Pereira Filho, Nancy Maria Martins de Oliveira Tobias, Bruna Affonso Madaloso, Mirella Esmanhotto Facin Instituto do Coração (InCor) do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP – Brazil Mailing Address: Carlos Alberto Pastore • Av. Dr. Eneas de Carvalho Aguiar, 44 AB. Postal Code 05403-000, Cerqueira Cesar, São Paulo, SP – Brazil E-mail: ecg_pastore@incor.usp.br Manuscript received September 19, 2018, revised manuscript January 10, 2019, accepted February 13, 2019 Keywords Electrocardiography/methods; Vectocardiography/methods; Electrophysiological Phenomena; Internal Medicine/methods DOI: 10.5935/abc.20190095 Abstract The electrocardiogram (ECG) has been reinvigorated by the identification of electrical alterations that were not definitely clarified before. In this context, and mainly regarding the definition of arrhythmogenic substrates, the association of the ECG with the vectorcardiogram (VCG) has gathered much more information about the cardiac electrical phenomena, thus allowing us to differentiate potentially fatal cases from benign ones. Obtaining a VCG concomitantly with the performance of an ECG has led to a significant gain in the definition of extremely sophisticated pathologies, which function suffer some type of structural or dynamic alterations, involving either the reduction or enhancement of ionic channels and currents. The classic aspects of the ECG/VCG association in the differential diagnosis of myocardial infarctions, conduction disorders, atrial and ventricular hypertrophies, and the correlations between these electrical disorders are still valid and assertive. The association of these pathologies is further clarified when they are seen through the ECG/VCG dyad. The three-dimensional spatial orientation of both the atrial and the ventricular activity provides a far more complete observation tool than the ECG linear form. The modern analysis of the ECG and its respective VCG, simultaneously obtained by the recent technique called electro-vectorcardiogram (ECG/ VCG), brought a significant gain for the differential diagnosis of some pathologies. Therefore, we illustrate how this type of analysis can elucidate some of the most important diagnoses found in our daily clinical practice as cardiologists. Introduction The study of vectorcardiography began during the 1940’s and publications reached a peak between the 1960’s and 1970’s, correlating this method with the heart diseases best known at that time. The great difficulty then was linked to the fact that the VCG device could not be easily moved around. The images were thus not immediately obtained, and so the vectorcardiogram was a tool to be used a posteriori to resolve doubts about specific electrocardiograms in some special situations. Additionally, the advent of echocardiography and its later improvement, as well as the emergence of computed tomography and magnetic resonance imaging, led to a decreased use of both the electrocardiogram and, mainly, of the vectorcardiogram from the 1980’s until the end of the 1990’s. This temporal gap, associated to a diminished interest in electrovectorcardiography, resulted in a significant decrease in the number of cardiology centers capable of performing and interpreting a vectorcardiogram. However,with thedevelopment of invasiveelectrophysiology (electroanatomic mapping), genetics and molecular biology, many electrical conditions have been unveiled, resulting in the identification of their clinical/electrocardiographic patterns, since such conditions can lead to sudden death. 1-7 The technological developments seen during the 1990s also affected electrovectorcardiography. The sophistication brought by the use of computers, algorithmic systems and Fourier transforms allowed us to obtain vectorcardiographic information in a much simpler and quicker form, in color, and as three-dimensional images. The electrocardiogram (ECG) was therefore reinvigorated by the identification of electrical alterations that had not yet been definitely observed, so that from the year 2000 until the present decade an increasing number of publications related to electrovectorcardiography has been observed. In this context, and mainly regarding the definition of arrhythmogenic substrates, it was observed that the association of the ECG and the vectorcardiogram (VCG) methods could provide much more information about the cardiac electrical phenomena, thus increasing its employment and allowing us to differentiate potentially fatal cases from benign ones. 8-10 We now find ourselves in a moment where the performance and reading of the vectorcardiogram is carried out in just a few specific centers around theworld.Moreover, our team is involved with the teaching of electrocardiography to undergraduate and postgraduate students in the medical area. Therefore, we feel there is an urgent need to teach vectorcardiography, considering that its spatial visualization of the cardiac electrical activation makes it a lot easier to understand and memorize the basic and more complex electrocardiographic notions. 11 Obtaining a VCG concomitantly with the performance of an ECG has led to a significant gain in the definition of extremely sophisticated pathologies, of which genetic mutations cause their function to suffer some type of structural or dynamic alterations, involving either the reduction or enhancement of ionic channels and currents. 87