The toolbar above 12-lead ECGs is used to access tools available for this type of ECG, such as calipers and zoom functions.

The first three buttons are use to access three caliper tools:

• Timing calipers measure time intervals.
• Voltage calipers measure voltages.
• Combined calipers measure both time intervals and voltages simultaneously.

Clicking on the Timing Button enables the Timing Calipers. To use the Timing Calipers:

1. Select on the toolbar.
2. Position the mouse at the starting point on the ECG using the left caliper arm as the starting point.
3. Click and hold down the left mouse button and drag the mouse left or right to the end point.
4. The interval in milliseconds is shown in the area under this toolbar.
5. If you release the mouse button and press it again over the highlighted area, you can slide the highlighted area left and right to see if complexes are regularly spaced or not.
6. If you release the mouse button and press it again over the shaded area, you will start a new measurement interval.
7. You can adjust the left and right positions by clicking and dragging on the vertical lines of the highlighted window. The cursor will change when it is over the line.
8. You can also interact with the Timing Caliper using the keyboard.

Clicking on the Voltage Button enables the Voltage Calipers. To use the Voltage Calipers:

1. Select on the toolbar.
2. Position the mouse at the starting point on the ECG using the left caliper arm as the starting point.
3. Click and hold down the left mouse button and drag the mouse up or down to the end point.
4. The voltage in millivolts is shown in the area under the toolbar.
5. If you release the mouse button and press it again over the highlighted area, you can slide the highlighted area up and down to compare the sizes of complexes.
6. If you release the mouse button and press it again over the shaded area, you will start a new measurement interval.
7. You can adjust the top and bottom positions by clicking and dragging on the horizontal lines of the highlighted window. The cursor will change when it is over the line.
8. You can also interact with the Voltage Caliper using the keyboard.

Clicking on the Combined Button enables the Combined Calipers. To use the Combined Calipers:

1. Select on the toolbar.
2. Position the mouse at the starting point on the ECG using the left caliper arm as the starting point.
3. Click and hold down the left mouse button and drag the mouse up, down, left or right to the end point.
4. The timing and voltage measurements are shown in the area under the toolbar.
5. If you release the mouse button and press it again over the highlighted area, you can move the measurement box around to compare the timing and sizes of complexes.
6. If you release the mouse button and press it again over the shaded area, you will start a new measurement box.
7. You can adjust the top, bottom, left and right positions by clicking and dragging on the horizontal and vertical lines of the highlighted window. The cursor will change when it is over the line.

The button turns off the calipers that you were using and clears the ECG display.

The button opens a new window that shows the entire enlarged ECG image. The new window may take a few seconds to appear, depending on the speed of your network connection. Please let us know if this feature does not work properly in your web browser.

The button displays patient demographics (age, sex, height, and weight) and clinical history in a popup window, if this information is available for the ECG. Just as with real clinical recordings, use your best clinical judgement when viewing this data. For example, if the height is given as 17 inches for a 56 year old person, the height measurement was probably transposed from 71 inches. The button will be disabled if demographics and clinical history are not available.

The button displays data about the ECG, such as Ventricular Rate, PR interval, QRS width, etc. These data, if available, are automatically extracted from the ECG and are not guaranteed to be verified. Just as with real clinical recordings, use your best clinical judgement when viewing this data. This button is only available on the Results page.

The Tour Button provides additional help on the individual controls on the page via popup windows attached to the individual controls on the page. To view this additional help:

1. Select from the toolbar.
2. Use the controls in the popups that appear to run through the tour.

The Help Button enables provides this help information in a popup window. To view help in a popup window:

1. Select from the toolbar.