Normal Variants (cont.)

Another way or representing lead III (remember your algebra?) is:
III = aVF + (-aVL) Putting it visually:

So an initial R wave in aVL which is quite common will translate into a Q wave in lead III. This Q wave can be very prominent at times but should not be misinterpreted as due to an inferior infarct. The same is true of the negative T wave in lead III. Notice in this case that a normal positive T wave in aVL is responsible for a negative T wave in lead III.