ECG Level 3 Tutorial: Axis
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Tutorial: Axis
This will teach a basic approach to determining the axis of an ECG.
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Tutorial: Axis Shading the QRS
Lessons
42
Times Practiced
1284
Cases Completed
1h 24m
Total Time spent
1m 24s
Average Time
Progress
Accuracy
Efficiency
Accuracy
Efficiency
1 Remember the Vector Remember the Vector
2 Quadrants Quadrants
3 Defining the Normal axis Defining the Normal axis
4 The Isoelectric lead The Isoelectric lead
Current lesson 5 Shading the QRS Shading the QRS
Shading the QRS
Sometimes, the QRS complex is difficult to determine if it is mostly upgoing or mostly downgoing. The most accurate way to determine if the ECG is mostly up-going vs. down-going is to look at the area under/above the curve. The 2 images below will help to illustrate this concept.

In the first image, we can see that the blue shaded region is greater than the red shaded region and therefore this QRS is mostly upgoing:
ECG axis determination

In the image below, again, the blue region is greater than the red region, and so this QRS is mostly downgoing:
ECG axis determination

If you really cannot tell which shaded region is greater, then the lead would be isoelectric. The second image above actually looks like the upgoing R wave is taller than the downgoing S wave (especially the 1st and 4th QRS), and if you said "hey man, those are pretty equal", then I would have to agree with you. This example is included to show how it can be difficult to determine up vs. down going portions in some examples.