ABC | Volume 113, Nº1, July 2019

Statement Position Statement on Indications of Echocardiography in Adults – 2019 Arq Bras Cardiol. 2019; 113(1):135-181 Thus, it was agreed that all the tables with recommendations for the use of echocardiography in the different clinical scenarios include columns with class of recommendation and level of evidence. 2. Evaluation of Heart Function and Structure 2.1. Left Ventricular Systolic Function The analysis of left ventricular (LV) systolic function is a primary indication of the use of echocardiography. Echocardiographic analysis of LV systolic function can be performed using older techniques such as M-mode, 2D echocardiography, and even more modern techniques, such as three-dimensional (3D) echocardiography or research of myocardial deformation (strain). The M-mode has been used since the 1950s for cardiac structural analysis and provides widely standardized measurements 1,2 of the dimensions of the cavity and the thickness of the LV. Thus, parameters of ventricular systole analysis are derived as: (1) percentage of systolic shortening of the left ventricular dimension, represented by the difference between the final diastolic and the final systolic dimensions, divided by the final diastolic one; (2) mean corrected circumferential shortening velocity, corresponding to the ratio between the percentage of systolic shortening of the left ventricular dimension divided by the ejection time corrected by the preceding R-R interval (ejection time divided by the square root of the R-R interval); (3) ventricular volumes at the end of systole and diastole, calculated from the method by Teichholz et al.; 3 and (4) LV ejection fraction (LVEF), obtained from the difference between the diastolic and systolic ventricular volumes (volume ejected by systole), divided by the diastolic volume. The M-mode analysis is highly reproducible and presents high temporal resolution for the analysis of ventricles without spatial deformation. 4 However, M-mode measurements, in general, adequately determine global systolic function only when there are no segmental changes, remodeling and/ or geometric alterations of the LV. 4 With the advent of 2D echocardiography, a greater amplitude of the LV spatial observation was acquired, allowing better analysis of the left ventricular systolic function, when compared to the one- dimensional analysis. This occurs in situations where there are changes in left ventricular geometry, such as apical aneurysm and other segmental changes resulting from coronary artery disease. The analysis of 2D left ventricular systolic function can be performed qualitatively (visual estimation) or quantitatively of LVEF. Visual estimation is highly dependent on the training of the operator, which can result in inaccuracy of reproduction of results. The quantitative method for volume and systolic function analysis of the most widespread and widely valid 2D-LV is the biplanar disc technique (modified Simpson’s rule), in which the total volume is calculated based on the sum of the volumes of small cylindrical discs in apical cuts 4 and 2 LV chambers, with the intention of minimizing the effects of modifying the ventricular geometry in LVEF calculation. 4 Normal volume ​and LVEF values, calculated using 2D echocardiography, show different values depending on gender. Thus, for men, the final LV diastolic volume is between 34 and 74 mL/m 2 , the final LV systolic volume is between 11 and 31 mL/m 2 and LVEF is between 52 and 72%; LV final diastolic volume is between 29 and 61 mL/m 2 , LV final systolic volume is between 8 and 24 mL/m 2 and LVEF is between 54 and 74%. 4 The 2D LVEF analysis may present inaccuracies during the shortening of LV (foreshortening) or inadequate acoustic window, and when there are coexistent geometric changes in the apical 4 and 2 LV chambers. 4 The analysis of LV segmental contractility by 2D echocardiography represents a semiquantitative technique to assess regional systolic function, which has shown good application in clinical practice, especially for stress echocardiography (calculus of parietal motility index, which integrates analysis of ventricular wall thickening and ventricular segment contractility). Tissue Doppler, a technique used in the analysis of diastolic function, can also be used to assess global and segmental LV systolic function. The systolic velocity of the ventricular myocardium (s-wave), when measured in the region of the mitral annulus, reflects the longitudinal myocardial systolic shortening and may be reduced early in patients with diastolic dysfunction and normal ejection fraction. 5 This method may also be useful for ventricular synchrony analysis and as a complement in stress echocardiography, although it does not allow adequate evaluation of systolic function in the apical LV segments and depends on the angle of incidence of the ultrasound beam. 3D echocardiography represented an improvement over 2D echocardiographic observation of LV function, once it does not present the limitations of the 2D analysis in ventricles with altered geometry, in addition to being more reproducible and better correlated with the gold standard provided by nuclear magnetic resonance. 4,6-11 Most recent algorithms allow the calculation of LVEF and LV volumes in a semi- automatic way, with great correspondence with the analysis performed by nuclear magnetic resonance. 12 However, 3D echocardiography presents difficulties in relation to low temporal resolution and to the dependence on transthoracic echocardiographic image quality. 4 The understanding and analysis of LV mechanics and systolic function can also be determined by the measurement of ventricular strain. Strain is defined as the modification of length of the myocardial segment (in %), considering the different spatial arrangements of the myocardial fibers. In this way, the longitudinal, circumferential and radial strain (for the respective longitudinal, circumferential and radial myocardial fibers) is calculated. The strain can be calculated for each of the LV segments or for all segments (global LV strain). 13,14 The analysis of the cardiac mechanics can be performed from parameters derived from myocardial deformation, such as twist, torsion and LV rotation. In order to obtain ventricular strain, the most commonly used technique takes into account the movement of gray points in the myocardium during the cardiac cycle (speckle tracking technique). 13,14 Global 2D strain has the advantages of not depending on the angle of the ultrasound beam (as in tissue Doppler) and of presenting an independent prognostic LVEF value. 4 However, it does not yet present a standardized value of normality among the different manufacturers of echocardiography equipment. 4 The LV global longitudinal strain (GLS) has been the one most 139