Introduction to Cardiac Strain for the ACUSON Redwood™ Ultrasound System USA

Welcome to the Introduction to Cardiac Strain for the ACUSON Redwood™ Ultrasound System.  The ACUSON Redwood ultrasound system uses syngo­® Velocity Vector Imaging (VVI) technology to assess myocardial motion, deformation, and mechanics non-invasively. In this course you will be introduced to a high-level overview of two-dimensional (2D) speckle-tracking methods used clinically to assess cardiac strain on the VVI workflow on the ACUSON Redwood ultrasound system.     Upon successful completion of this course you will be able to:   Understand speckle-tracking echocardiography (STE) and speckle-tracking methods  Examine STE deformation, timing, and mechanics Congratulations. You have just completed the course Introduction to Cardiac Strain for the ACUSON Redwood™ Ultrasound System. Thank you for your interest in ultrasound! Listed below are the key points. Take time now to review the material here before proceeding to the final assessment. Course Review Understand speckle-tracking echocardiography (STE) methods  Examine STE deformation, timing, and mechanics Doppler Tissue Imaging (DTI) and Pulse Wave (PW) spectral DTI is a relatively fast way to compare regional wall motion changes.   Learn more below.   Doppler Tissue Imaging Learn more about Doppler Tissue Imaging. Tab TitleTextColor DTIOn the Redwood Ultrasound system DTI and PW Doppler are avaliable using the cardiac preset on all of the 5V1, 8V3, and the 10V4 transducers. First, activate Color from the control panel and then select DTI from the touch screen.    PW DTIPW DTI provide regional information about timing and relative velocities of individual wall motion segments. To initiate the spectral PW DTI signal first, activate the PW/CW from the control panel and then select the DTI option on the touch screen.     Angle DependencyTDI is used for regional wall-motion analysis but it is not well suited for global functional assessment due to the angle dependency of Doppler imaging. In this example the PW spectral Doppler is being sampled from the septum of the heart. In the image on the left, the Doppler cursor and sample volume are in line with the septum and will yield an accurate velocity. In the image on the right, the Doppler cursor and sample volume are at an angle which will underestimate the velocity. Unlike Doppler imaging, speckle-tracking echocardiography (STE) is not affected by the angle of intercept. STE is an image-based method that is used to track, or follow the same group of tissue speckles in an image from frame to frame during the cardiac cycle. The software analyzes the deformation, tissue velocity and other parameters related to movement of the 2D image. In this example, the software output shows STE parametric waveforms and values along with volume, LVEF, heart rate, cardiac output, and regional velocities.    The strain is the deformation between two points measured as the change in length divided by the original length.   The strain is the deformation or change in length from one point to another. Strain Introduction Learn more about how strain is calculated here. Instructions:Flash File:HTML5 File:/content/generator/Course_90022828/3.strain_intro_800x600/index.htmlPDF File: Cardiac strain is the measurement of change in the positive or negative direction. Select the exercise below for more information. Negative and Positive Strain Learn more about negative and positive strain. Instructions:Flash File:HTML5 File:/content/generator/Course_90022828/2.neg_pos_800x600/index.htmlPDF File: 2D speckle tracking methods used clinically include global longitudinal strain (GLS), global circumferential strain (GCS), and radial strain. Each strain method utilizes a region of interest or ROI.  The ROI is a contour along the endocardium at the blood interface and is further expanded across to the myocardium and divided into segments. Speckle tracking analyzes and references the changes in movement within the contour.   Review each of the speckle tracking methods in this exercises below.     GCS Learn more about global circumferential strain here. Slide NumberText BlocksCalloutsAudio ScriptImage File1Global Circumferential Strain or GCS is measured perpendicular to longitudinal strain in the cross sections of the heart from the parasternal short axis (PSAX) views.  The strain contour for GCS is typically added at three PSAX views: mitral valve level, papillary muscle level, and at the PSAX  apex. As discussed earlier, strain is the deformation (change in length) divided by the original length, multiplied by 100. In this example L1 is the original length, this deforms / shortens circumferentially to a the length L2.   Let's assign values to L1 and to L2.  The original length of L1 is equal to 12 cm and L2 shortens to 8 cm. This yields a -4 cm change in length. -4 is divided by 12 and then multiplied by 100. The product is a deformation of -33%.  Circumferential strain is the relative shortening perpendicular to the wall segment resulting in shortening so the strain value is negative.  CalloutsOriginal Length = 12 cmShortened length = 8 cmGlobal Circumferential Strain or GCS is measured perpendicular to longitudinal strain in the cross-sections of the heart from the parasternal short axis (PSAX) views. The strain contour for GCS is typically added at three PSAX views: mitral valve level, papillary muscle level, and at the PSAX apex. As discussed earlier, strain is the deformation (change in length) divided by the original length, multiplied by 100. In this example L1 is the original length; this deforms/ shortens circumferentially to length L2. (pause) Let's assign values to L1 and L2. The original length of L1 is equal to 12 cm, and L2 shortens to 8cm. This yields a -4 cm change in length. -4 is divided by 12 and then multiplied by 100. The product is a deformation of -33%. The circumferential strain is the relative shortening perpendicular to the wall segment, resulting in shortening, so the strain value is negative. 2The GCS width can include the three muscle layers the endocardium, myocardium, and epicardium taking care to avoid the pericardial layer. Circumferential strain from the endocardial interface is the most reproducible method.  Circumferential strain from the endocardial interface is the most reproducible method. CalloutsAortic Valve Closes (End-Systole)Mitral Valve Closes (End-Diastole)The GCS width can include the three muscle layers (endocardium, myocardium, and epicardium taking care to avoid the pericardial layer. Circumferential strain from the endocardial interface is the most reproducible method. 3Clinically, longitudinal and circumferential strain methods should align.  Both depict relative shortening. Let’s review some ways to improve reproducibility and avoid variability in global circumferential strain.  Visually assess the tracking contour and modify the contour as often as necessary to achieve maximum contour tracking. Avoid the pericardial layer, the GCS width can include the endocardium and mid-wall at the myocardium. Ignore the papillary muscles when creating the ROI. ​Avoid translation motion as much as possible by collecting clips from end expiration. Do not include regions that do not track well and document any variation in the methods used to calculate GCS. Clinically, longitudinal and circumferential strain methods should align. Both depict relative shortening. Let’s review some ways to improve reproducibility and avoid variability in global circumferential strain. • Visually assess the tracking contour and modify the contour as often as necessary to achieve maximum contour tracking. • Avoid the pericardial layer; the GCS width can include the endocardium and mid-wall at the myocardium. • Ignore the papillary muscles when creating the ROI. • Avoid translation motion as much as possible by collecting clips from end-expiration. • Do not include regions that do not track well and document any variation in the methods used to calculate GCS. 4A comparison of longitudinal or circumferential strain is a useful clinical companion to LVEF. There are clinical circumstances where the longitudinal strain is not specific and circumferential strain may be a useful ‘tie-breaker’. A circumferential strain may be useful to include along with other biomarkers to monitor cardiac function when comparing serial studies and there are disagreements in LVEF and longitudinal strain results. In this graphic representation, circumferential is in red and is compared to longitudinal strain is represented by the orange curve.  A comparison of longitudinal or circumferential strain is a useful clinical companion to LVEF. There are clinical circumstances where the longitudinal strain is not specific and circumferential strain may be a useful ‘tie-breaker.’ A circumferential strain may be useful to include along with other biomarkers to monitor cardiac function when comparing serial studies and there are disagreements in LVEF and longitudinal strain results. In this graphic representation, circumferential is in red and is compared to and longitudinal strain represented by the orange curve. Radial Strain Learn about radial strain here. Tab TitleTextRadial Strain The radial strain contour is assessed at the PSAX views and radial is deformation that is tracked perpendicular to the long axis of the heart and is also perpendicular to the myocardium.  Radial speckle patterns are moving away, lengthening, so the strain results are positive. Clinically, radial strain methods lack wide acceptance compared to circumferential and longitudinal methods, and radial strain remains the least consistent between operators, vendors, and software. Global Longitudinal Strain Learn more about global longitudinal strain here. Slide NumberText BlocksCalloutsAudio ScriptImage File1Speckles track movement for longitudinal strain along the length or the long axis of the heart. Longitudinal strain is the change in the length of a line that is drawn along the myocardium and mid or epicardial wall. The deformation in length is divided by the original length and longitudinal strain results are a negative values. Let's assign values to L1 and L2.  L1, the original length is 10 cm and L2 shortens to 8 cm.  This yelds a -2 cm change in length.  The negative strain result may seem confusing because functionally, the walls are thickening but the difference is from the reduction in length not the thickness.  Next, divide -2 by the original length of 10 cm, multiply by 100 and the product is a deformation of -20%.   The global longitudinal strain (GLS) is measured at Apical 4-chamber (A4), Apical 3-chamber (A3), and Apical 2-chamber (A2) views.CalloutsL1L2Speckles track movement for longitudinal strain along the length of the long axis of the heart. Longitudinal strain is the change in the length of a line that is drawn along the myocardium and mid or epicardial wall. The deformation in length is divided by the original length, and longitudinal strain results are displayed as negative values. (pause) Let's assign values to L1 and L2. L1, the original length is 10 cm, and L2 shortens to 8 cm. This result yields a -2 cm change in length. The negative strain result may seem confusing because functionally, the walls are thickening but the difference is from the reduction in length, not the thickness. Next, divide -2 by the original length of 10 cm, multiply by 100 and the product is a deformation of -20%. The global longitudinal strain (GLS) is measured at Apical 4-chamber (A4), Apical 3-chamber (A3), and Apical 2-chamber (A2) views. 2The thickness of the segments can be expanded perpendicularly and manually or automatically adjusted to span across the entire thickness of the endocardium, myocardium, and epicardium. This increases the speckles tracked; however, the most common and most reproducible GLS is just sampled at the endocardium.Global Strain from the endocardial interface is considered the most reproducable method. CalloutsAortic Valve Closes (End-Systole)Mitral Valve Closes (End-Diastole)The thickness of the segments can be expanded perpendicularly and manually or automatically adjusted to span across the entire thickness of the endocardium, myocardium, and epicardium. This increases the speckles tracked; however, the most common and most reproducible GLS is just sampled at the endocardium. 3Let's review some ways to improve reproducibility and avoid variability in GLS. Visually assess the tracking contour and modify the contour as often as necessary to achieve maximum contour tracking. Avoid the pericardial layer this will reduce the GLS value. GLS width can include the endocardium and mid-wall at the myocardium. Ignore the papillary muscles when creating the ROI. Avoid translation motion artifact as much as possible by collecting the clip from end expiration. Do not include regions that do not track well and document any variations in the methods used to calculate GLS for future exams. Let's review some ways to improve reproducibility and avoid variability in GLS. (pause) • Visually assess the tracking contour and modify the contour as often as necessary to achieve maximum contour tracking. • Avoid the pericardial layer this will reduce the GLS value. • GLS width can include the endocardium and mid-wall at the myocardium. • Ignore the papillary muscles when creating the ROI. • Avoid translation motion artifact as much as possible by collecting the clip from end-expiration. • Do not include regions that do not track well and document any variations in the methods used to calculate GLS for future exams. With muscle contraction the wall shortens from the original length and the tangential arrangement of the heart muscle layers (endocardium, myocardium, and epicardium) combined to create the twisting action of the muscle layers in cross section. Learn more about cardiac dynamics below.   Cardiac Dynamics LV Review basic left ventricular cardiac dynamics here. Slide NumberText BlocksCalloutsAudio ScriptImage File1 The subendocardial and epicardial fiber alignment creates a wringing effect and moves the base of the heart toward the apex. The base of the heart rotates clockwise against the counterclockwise twist at the apex.   The subendocardial and epicardial fiber alignment creates a wringing effect and moves the base of the heart toward the apex. The base of the heart rotates clockwise against the counterclockwise twist at the apex.2 The myocardium contracts and the muscle shortens, reducing the left ventricular (LV) cavity size. The LV pressure then rises, note the white arrow, this causes the aortic valve to open, note the orange arrow.   CalloutsAortic Pressure wave at the orange arrow.Left Ventricular Pressure at the white arrow.The myocardium contracts and the muscle shortens, reducing the left ventricular (LV) cavity size. The LV pressure then rises, note the white arrow, this causes the aortic valve to open, note the orange arrow.3 In diastole, the reverse occurs when the concentration of calcium falls, and the myocardial muscle relaxes, lengthening the heart from base to apex. This draws blood into the ventricle, and the aortic valve closes, note the green arrow. CalloutsAortic PressureLeft Ventricular PressureIn diastole, the reverse occurs when the concentration of calcium falls, and the myocardial muscle relaxes, lengthening the heart from base to apex. This cardiac action draws blood into the ventricle, and the aortic valve closes, note the green arrow.4Review this graphic representation of normal waveforms. The R-wave is from the electrocardiographic (ECG) tracing. The aortic and left ventricular pressure curves are from the two previous slides. Note that peak strain occurs after the aortic valve closes.  CalloutsR-wave ECGR-wave ECGAortic Valve DopplerMitral Valve DopplerAortic Valve OpensAortic Valve Closes (End-Systole)Mitral Valve Closes (End-Diastole)Negative Strain CurvePeak Strain Review this graphic representation of normal waveforms. The R-wave is from the electrocardiographic (ECG) tracing. The aortic and left ventricular pressure curves are from the two previous slides. Note that peak strain occurs after the aortic valve closes. Timing Learn more about deformation across the cardiac cycle. Slide NumberText BlocksCalloutsAudio ScriptImage File1The deformation of the LV occurs across the cardiac cycle. Maximim LV length occurs at end-diastole and can be timed using the R-peak from the ECG tracing.  The syngo® Velocity Vector Imaging™ (syngo VVI) software will use the ECG to automate timing of end-systole and end-diastole. CalloutsR-wave peak from ECG tracing.R-wave peak from ECG tracing.The deformation of the LV occurs across the cardiac cycle. Maximum LV length occurs at end-diastole and can be timed using the R-peak from the ECG tracing. The syngo® Velocity Vector ImagingTM (syngo VVI) software will use the ECG to automate timing of end-systole and end-diastole. 2LV end-systole occurs when the aortic valve (AV) closes. Normal strain peaks just after the aortic valve close. The timing of events is estimated by the STE software using the ECG and deformation of the speckles to create the approximation of the volume curves. In this example, the AV and LV pressure wave is superimposed next to the ECG to demonstrate timing events.   CalloutsAortic Pressure Aortic Valve Closes (End-Systole)Left Ventricular PressureLV end-systole occurs when the aortic valve (AV) closes.Normal strain peaks just after the aortic valve closes. The timing of events is estimated by the STE software usig the ECG and deformation of the speckles to create the approximation of the volume curves. In this example, the AV and LV pressure wave is superimposed next to the ECG to demonstrate timing events.3However, if there is not a precise match of end-diastole on the ECG due to a conduction delay, or the ECG is unreliable, end-diastole can be affiliated on the VVI software using M-mode of the LV (M-mode from the LV seen in this example). In this example, the AV and LV pressure wave is superimposed onto an M-mode from the LV to demonstrate timing events. Syngo VVI software uses a derived M-mode as a supplement for absent or deficient ECG signals  CalloutsLV (End-Systole) LV (End-Diastole)However, if there is not a precise match of end-diastole on the ECG due to a conduction delay, or the ECG is just unreliable, end-diastole can be affiliated on the VVI software using M-mode of the LV (M-mode from the LV seen in this example). In this example, the AV and LV pressure wave is superimposed onto an M-mode from the LV to demonstrate timing events. The syngo Velocity Vector Imaging (syngo VVI) software uses a derived M-mode as a supplement for absent or deficient ECG signals. 4Additionally, timing can be done by using pulse wave (PW) Doppler of the MV mitral valve.  AV closure using PW Doppler may also be necessary to accurately define AV closure and end-systole. In this example, the AV and LV pressure wave is superimposed over the Doppler signals from the Aortic Valve outflow and Mitral Valve inflow  to demonstrate timing events. Doppler described above is supplementary information for consideration of timing events. The syngo VVI software uses a derived M-mode as a supplement for absent or inadequate ECG signals.   CalloutsAortic Valve OpensAortic Valve ClosesMitral Valve OpensMitral Valve ClosesAdditionally, timing can also be done by using pulse wave (PW) Doppler of the MV mitral valve. AV closure using PW Doppler may also be necessary to accurately define AV closure and end-systole. In this example, the AV and LV pressure wave is superimposed over the Doppler signals from the Aortic Valve outflow and Mitral Valve inflow to demonstrate timing events. Doppler described above is supplementary information for consideration of timing events. The syngo VVI software uses a derived M-mode as a supplement for absent or inadequate ECG signals. Global lngitudinal strain is a valuable complement to traditional measurements for monitoring patients at risk of heart failure because strain provides mechanical deformation and contraction information to support clinical diagnostic capabilities.  Learn more below. Clinical Strain Review some clinical parameters from STE. Tab TitleTextGLSGLS is as a valuable complement to traditional echocardiographic parameters for monitoring patients at risk of heart failure because both support clinical diagnostic capabilities by providing mechanical deformation and contraction information.  Speckle-tracking analysis extracts contour-fitting curves and parametric information from the tracking software with an output of LV volumes, wall velocity, displacement, LVEF, strain and strain rate across the cardiac cycle.                                        This is a graphic representing normal GLS.  On the y-axis (vertical axis) is the strain percentage and the x-axis (horizontal axis) is the displacement curve shown as a percentage of the entire cardiac cycle.  The vertical axis line intersects where the AV closes. Normal and Reduced GLSIn this example the blue GLS shape is reduced as compared to the normal GLS shape in red.  However, the normal GLS and the reduced GLS track synchronously with each other across the heart cycle.                               As seen in the previous example, the y-axis is the strain percentage and the x-axis is the displacement curve shown as a percentage of the entire cardiac cycle. Again, the black line represents the AV closure.  Timing and STE In this example, the normal GLS is in red and mildly reduced GLS shape is in blue.  Premature shortening is shown in the orange curve and dyssynchrony is shown in the aquamarine GLS shape.                             In populations without structural heart disease, the peak systolic strain correlates to the closure of the AV. Cardiac dyssynchrony, coronary artery disease (CAD), and ischemic heart disease have peak strains that are out of phase with aortic valve closure. Speckle-trsacking analysis extracts contour-fitting curves that demonstrate the dispersion in timing from peak systolic strain (and volume) to AV closure.  These changes can be measured accurately, and the waveforms provide a visual display of mechanical dispersion in patients with dyssynchrony and structural heart disease. LVEF and GLS Speckle-tracking analysis extracts contour-fitting curves and parametric information from the tracking software with an output of LV volumes, wall velocity, displacement, LVEF, strain and strain rate across the cardiac cycle. In patients with subclinical ventricular dysfunction, compensatory mechanisms may preserve the LVEF or there may be non-significant changes in LVEF.  Combining GLS and LVEF helps to stratify risk factors in cardiac pathologies that do not cause a significant change to the LVEF. Also, adding circumferential strain will help provide additional information.   GLS and GCS Chronic reduction in perfusion over time and subclinical fibrotic damage to the myocardium changes the tone of the subendocardial tissue along the longitudinal axis of the heart. Endocardial and myocardial fibers aligned circumferentially are additive and circumferential tone will increase, compensating for weakening longitudinal tone. Circumferential strain may help unmask preclinical heart failure and early subclinical myocardial fibrosis.  GLS and GCS methods cannot be compared one-to-one; however, trends between the two methods may be useful. For example, if there are multiple GLS results on a single exam, GCS will trend a result that helps provide a clinical ‘tie-breaker’.  In the VVI software, there is a shape function curve that may be used to can help identify LV remodeling as a result of maintaining systolic function to preserve LVEF.   If the shape function identifies remodeling, and a reduced GLS, this may indicate to the clinician that additional circumferential strain analysis could be used in collaboration with GLS and other biomarkers to monitor cardiac function.   Cancer Therapeutic Related Cardiac Dysfunction Long-term echocardiographic monitoring is recommended for cancer therapeutics-related cardiac dysfunction (CTRCD). CTRCD is defined as a ≥5% drop in LVEF in symptomatic patients and a decrease of ≥10% to an LVEF of 53%. The diminishing LVEF may be related to patient-loading conditions or related to early cardiac dysfunction. When the longitudinal shortening diminishes, circumferential mechanics may compensate for LVEF, and adding GCS to GLS may provide additional information as an early predictor of cardiotoxicity. Beyond the methods used, variability in STE is multi-factorial. Next, we will discuss some basic considerations that may help minimize STE variability for GLS. Managing Variability Review some components of variability in STE. Tab TitleTextSerial GLS Clinicians should maintain the same system type and software level when performing serial GLS measurements as software algorithm differences will impact the results. Note any variations in apical views or omitted regions  used for a particular GLS analysis. These differences can be taken into consideration for future follow-up exams. The ASE Strain Task Force recommends using the same ultrasound platform and software for serial evaluation.   Image Quality Consider that variation in image quality affects all 2D imaging analysis. However, variation in image quality and less distinct endocardial borders will cause uncertainty in the analysis of 2D strain because the tracking algorithm cannot differentiate between noise and structural speckle.   Foreshortening Care must be taken not to foreshorten the apical views as malalignment of the primary axis will introduce inaccuracies. The entire myocardium—mid to epicardium—should be seen. The pericardium border also should be in view as the pericardium should be the external boundary for strain analysis and not be included in the analysis of GLS. Translation Motion This is a lateral movement of the heart within the chest, typically caused by breathing, and will introduce uncertainties in tracking results. Clinicians should reduce translation motion as much as possible by collecting cini-loop image data from the end expiration. Frame Rate Learn more about frame rate and frames per cycle. Instructions:Flash File:HTML5 File:/content/generator/Course_90022828/2.frame_rate_frames_redwood800x600/index.htmlPDF File: The reproduction, transmission or distribution of this training or its contents is not permitted without express written authority. Offenders will be liable for damages. All names and data of patients, parameters, and configuration-dependent designations are fictional and examples only. All rights, including rights created by patent grant or registration of a utility model or design, are reserved. Copyright © Siemens Healthcare GmbH, 2020 Please note that the learning material is for training purposes only! For proper use of the software or hardware, always use the Operator Manual or Instructions for Use (hereafter collectively called “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute for the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of software and hardware available at the time of the training. The Operator Manual shall be used as the main reference, in particular for relevant safety information like warnings and cautions. Note: Some functions shown in this material are optional and might not be part of the learner’s system. The information in this material contains general technical descriptions of specifications and options as well as standard and optional features that do not always have to be present in individual cases. Certain products, product-related claims or functionalities described in the material (hereafter collectively called “Functionality”) may not (yet) be commercially available in the learner’s country. Due to regulatory requirements, the future availability of Functionalities in any specific country is not guaranteed. Please contact your local Siemens Healthineers sales representative for the most current information. Quantification methods must be consistent for meaningful value comparisons of serial exams and monitoring. A clinician must be aware of the differences in methods and calculated values for LVEF and quantification of strain.   Standardization LV STE Review Strain Task Force recommendations here. Tab TitleTextASE and EACVI The American Society of Echocardiography (ASE) and the European Association of Cardiovascular Imaging (EACVI) combined to create a consensus and standardize deformation imaging.  The ASE and EACVI created a Strain Task Force with the ongoing goal of standardizing the clinical use of STE for functional evaluation of the heart. The Strain Task Force has recommended that GLS is the most reproducible 2D STE method. Furthermore, the Strain Task Force has recommended that GLS from the endocardial interface is a sensitive indicator of dysfunction and considered the most reproducible of the 2D strain methods. Endocardial GLS Of the three common STE methods, the Strain Task Force recommends GLS, specifically endocardial GLS, because it is a sensitive indicator of dysfunction and considered the most reproducible of strain methods. The most consistent methods for GLS are from the endocardial interface GLS. The width of the contour across the endocardium, myocardium, and epicardium will affect the GLS values, standards, and guidelines at specific myocardial, sub-myocardial, subepicardial or epicardial layers, and a combination of layers is of unknown clinical value. Additionally, the Strain Task Force has recommended that LVEF and GLS values become part of standardized reporting.   GLS Values Guidelines from many subject expert authors and Strain Task Force suggest a normal baseline GLS value of -20% with a standard deviation of ~± 2%. However, depending on the ultrasound platform and STE software used, normal GLS has been reported in the range of -15.9% to -22.1%. The GLS values can vary and are multifactorial.   syngo® Velocity Vector Imaging™ technology (syngo VVI) is a clinical software application avaliable on the Redwood ultrasound system and is used to visualize, measure and assess myocardial motion and mechanics from 2D clips. syngo VVI utilizes the user-defined contour and tracks the tissue and estimates the tissue velocity and other motion mechanics and deformation parameters. Quantitative data is derived from the syngo VVI software that is represented as curve plots, parametric M-mode graphs, and parametric segmental diagrams. The results are dependent on the views selected and used to draw the contour and the selected parameters such as velocity, displacement, strain, and or strain rate.   The References used are avaliable in the popup below. References References 1 F H Sheehan, et al., Advantages and applications of the centerline method for characterizing regional ventricular function. Circulation  1986. 74: p. 293 - 303. 2 Klein, P.C.D.P.A., A Test in Context: Myocardial Strain Measured by Speckl-Tracking Echocardiography. Journal of the American College of Cardiology, 2017. 69: p. 1043 - 1054. 3 Chung, C.S., How myofilament strain and strain rate lead the dance of the cardiac cycle. Archives of Biochemistry and Biophysics, 2019. 664: p. 62-67. 4 Janssen, P.M.L., Myocardial contraction-relaxation coupling. 2010: p. H1741 - H1749. 5 Potter, E. and T.H. Marwick, Assessment of left ventricular function by echocardiography: the case for routinely adding global longitudinal strain to ejection fraction. 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