How to manage the visualization and modification of mean patterns? - Advanced ECG module (ECG Delineation Analyzer).
This article provides the key steps for visualizing, selecting, and adjusting cardiac mean patterns with the LASA software using the ADVANCED ECG module. The software interface, which displays the PQRST morphology and allows cycle editing (exclusion, moving, or adding events), can be used to refine automated detection or correct specific signal artifacts, ensuring the high quality of the calculated physiological intervals.
LASA software offers great flexibility for evaluating cardiac function through its multiple visualization modules. Among the tools available to analyze the electrocardiographic signal, the advanced delineation module (Advanced ECG) provides several graphical representations allowing the exploration of morphology and physiological signals from different angles.
The Conduction Interval view is a powerful tool for tracking the temporal evolution of ECG delineation parameters. These parameters are calculated from a mean pattern, generated by overlapping several ECG complexes (60 cycles by default) to smooth noise and eliminate abnormal detections.
To fully leverage this functionality, it is essential to know how to display this pattern and how to adjust it, either directly from the standard ECG trace (raw signal) or via the dedicated windows and modules for ECG delineation.
1. Displaying the Pattern in the Conduction Interval View
By default, the Conduction Interval view displays the evolution curves of cardiac intervals calculated over time. Like other views available in the LASA software, this view initially presents the averaged points of the calculated parameters and not the pattern-by-pattern cardiac values.
To display the pattern-by-pattern values in parallel as well as the mean ECG pattern, apply the following procedure:
Configuration Verification: Ensure beforehand that the advanced delineation module (Advanced ECG) is properly activated in the LASA software via the detection configuration window (Detect Config) of your study. If the Advanced ECG module is missing, it will not be visible. If it is present but was not activated, check it and restart the detection.
Pattern Display: Once detection is launched, click on MERGE. Click on the gear icon available at the top middle of the screen. In the graphical interface, uncheck the option "Displayed mean parameters". This action visually displays the averaged PQRST pattern (represented in a dedicated frame) next to the interval graphs. Finalize your choice by selecting the CONDUCTION INTERVALS view in the CARDIAC tab.
The PQRST delineation view also allows displaying the mean pattern, but only that, with no other associated parameter.
Data Consultation:
>Tracking and Inspection of All Patterns (First Line): Located at the very top of this view, this first line groups all patterns generated throughout the recording, ensuring continuous temporal and sequential tracking. In this zone, a dedicated frame visually presents the averaged morphology of the PQRST complex to precisely observe the positioning of physiological events (Ppeak, Rpeak, etc.). Click on one of the crosses representing an event on the graph to open the raw ECG data used to generate the pattern.
Display Tip: If the global ECG trace obstructs your targeting of a point and you can't click on an event (e.g., T peak), you can easily hide it temporarily by clicking on the ECG_pattern field in the legend located on the right of the screen.
> Graphical Representation of Intervals (Following Lines): Arranged just below, these graphs trace the temporal evolution of parameters and cardiac intervals. The displayed data corresponds to the values calculated pattern by pattern, in perfect correlation with the chronology of the upper line. Hovering over the desired point with the cursor dynamically displays detailed textual information. A simple click on this point then opens a popup displaying the associated mean pattern.
> Identification of Signal Interruptions: Any absence of a pattern on the upper line visually signals data interruptions or signal segments whose quality was insufficient to allow validation by the module.
2. Modification and Adjustment of Patterns.
If wave morphology or the presence of artifacts (movements, grooming) alters the relevance of the automatic mean pattern, the user can manually correct or refine the positioning of events or the inclusion of cycles. Two complementary software approaches allow access to editing mode.
Approach A: Modification via Dedicated Delineation Views (Advanced ECG)
This method is preferred for excluding specific cycles from the mean pattern calculation or for graphically adjusting a pattern from the module's delineation windows.
1- Opening the Adjustment Interface: From the CONDUCTION INTERVAL view (with the "Displayed mean parameters" option unchecked), click on one of the crosses representing an event on the graph or on a calculated parameter point. As explained in the previous data consultation section, this opens a targeted inspection popup displaying the raw ECG cycles that allowed the formation of the pattern (event) or the corresponding mean pattern (calculated parameter).
2- Activating Edit Mode: From this popup, click on the Pencil icon to activate the cycle editing mode (Edit Mode). The physiological cycles then appear with a color code.
3- Actions: You can exclude, modify, or add cycles one by one by clicking directly on the colored zone representing the cycles degraded by an artifact.
Need details on precise manipulations?
To know the advanced procedures within this delineation interface (such as global exclusion via the "EXCLUDE ALL DISPLAYED CYCLES" button or using the SAVE / DISCARD button to automatically recalculate physiological parameters), please refer to the step-by-step instructions in the technical article
Approach B: Modification via the Standard ECG View (Continuous Raw Signal)
This method allows intervening directly on the complete continuous ECG signal instead of going through the summary windows of the delineation module.
1- Accessing the Raw View: Open the gear icon located at the top of the MERGE visualization interface. Choose the SIGNAL view in the CARDIAC options.
2-Configuring the Time Window: For the SIGNAL view to become available and display on the interface, you must imperatively select and zoom in on an appropriate time window, whose time base is strictly less than 20 minutes.
3- Activating Edit Mode: Click on the EDIT MODE button located on the left side of the upper banner of the view. The view immediately adapts to allow graphical modifications.
Need details on precise manipulations?
Fine modification of markers on the continuous raw ECG signal (such as adding undetected cycles by marking the beginning and end of the complex, or precisely moving misplaced events like R peaks, Vmax, and Vmin using the arrow keys `←` `→` and the validation key `V`) requires strict methodological precision. All of these graphical configurations and keyboard shortcuts are detailed in the technical article