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Instructions for Measuring VHS

1. To begin VHS measurements, click the “Measure” button in the toolbar.
2. Measure VHS: Move your mouse to the base of the heart (intersection of the ventral tracheal shadow & pulmonary vessels) click and hold the button down while dragging the green line to the apex of the heart. Release to complete the line.
3. Move your mouse to the cranial aspect of the cardiac silhouette, at the mid-point. Click and hold while dragging the purple line to the caudal border at the level of the ventral border of the vena cava (if it can be identified) or the widest part and release to complete the line. Green and purple lines should be approximately 90 degrees to each other.
4. Move your mouse to the cranial aspect of the 4th thoracic vertebra. Click and hold while dragging to show the green (long-axis) line and drag the line to the right with your mouse, rotating as needed to align the line parallel to the spine. Release to complete the line. The new green line will automatically be the same length as the green line that you drew representing the long-axis of the heart.
5. Click again at the cranial aspect of the 4th thoracic vertebra and hold while dragging to show the purple (short-axis) line and drag the line to the right with your mouse, rotating as needed to align the line parallel to the spine. Release to complete the line. The new purple line will automatically be the same length as the purple line that you drew representing the short-axis of the heart.
6. Count the number of vertebral bodies covered by each line to the nearest 0.1 vertebral bodies. Type the numbers into the appropriate boxes in the bottom tool bar. The sum of these 2 numbers is the VHS. Click the submit button on bottom tool bar. This will bring up a text box that shows the VHS measured by the CEG. A general goal for repeatability among different examiners is +/- 0.25 vertebral bodies. However, studies have shown much greater differences occur between observers (about 0.5 VB is the typical difference). To view the CEG VHS measurements click on the Annotated Image button on the top tool bar.