Advanced ECG Caliper User Guide – Srinivasa Satti, MD

Upload Button: Allows you to upload an image of an ECG strip in JPEG or PNG format.

Click on the “Upload” button and select an image to load it into the app for analysis.

Zoom Slider: Use the slider to adjust the zoom level of the ECG image (between 100% and 400%). This is helpful for analyzing the ECG strip in greater detail.
Mode Selector: The “Mode” dropdown has three options:

Calibrate: Allows you to adjust the calipers to calibrate the measurement scale. To calibrate, adjust the red line to a known interval, typically 200 ms, which is represented by 5 small boxes or 1 large box on the ECG.
Caliper: Measure specific intervals on the ECG strip, like HR, PR, QRS, QT, and QTc. You can manually enter values or use the blue measurement line for measurements. Checking the “March” box repeats the interval across the entire strip.
Intervals: Place up to five points on the ECG to measure the PR, QRS, QT, and RR intervals.

Reset Button (available in Interval mode): Clears any measured points and resets the interval measurements.
Measurement Controls:

You have buttons and input fields for measuring various intervals like HR, RR, PR, QRS, QT, and QTc.
Clicking on the buttons will display measurements derived from the calipers.
You can also manually enter values in the input fields, and the app will auto-calculate related fields. For instance, entering RR will calculate the HR and vice versa.
Normal ranges for each measurement are displayed next to the input fields.

Click the “Upload” button and select an ECG image file. The app accepts JPEG and PNG formats.

Select “Calibrate” mode from the mode selector.
Adjust the red caliper line to match the known 200 ms interval on the ECG. Drag either end of the line until it spans the appropriate number of boxes (5 small boxes or 1 large box).

Switch to “Caliper” mode to begin measuring.
Use the blue line to measure between points of interest (e.g., R-R interval).
You can drag either end of the vertical line horizontally using the circle handles.
You can move the whole caliper in any direction using the center circle handle on the horizontal line.
The March option will extend the interval measurement across the strip, useful for identifying consistent patterns.
Values will be displayed above and below the line, indicating the interval in milliseconds and the corresponding heart rate (bpm).

In “Intervals” mode, you can place 5 points on the ECG to calculate the PR, QRS, QT, and RR intervals. Click on the following points: start of PR, start of QRS, end of QRS, end of T wave, and the start of the next QRS. You can click on these points in any order.
Click on the ECG strip to place the points, and the intervals will be automatically calculated and shown in the input fields. After all five points are clicked, you can adjust the position of any of the caliper lines.
If you make a mistake, click the red reset button to clear the caliper lines and start over again.

Adjust the zoom level with the Zoom Slider to get a closer view of the ECG details.
Click and drag to pan across the ECG image when zoomed in.

When uploading an ECG image file, use the phone’s edit feature to rotate, crop, and correct for any parallax before uploading into the app for accurate measurements.
Ensure you’ve calibrated correctly before measuring intervals to maintain accuracy.
Use the zoom function to get a closer look at key parts of the ECG strip for better accuracy when placing calipers.
Use the “Reset” button to clear measurements in the ‘Intervals’ mode and start again if needed.
If you cannot see the calipers, zoom out to the full view of the ECG strip.

If you have any further questions or need additional guidance, feel free to reach out!