When determining the axis of the heart in the transverse (horizontal) plane, the point in which the QRS complex becomes isoelectric (transitions from negative to positive) occurs after lead V4.

•If you were looking up at the heart from beneath, the heart appears to be rotated clockwise, making the transition point in lead V5 or V6 instead of V3 or V4, which would be normal.

•ECG finding:

•QRS complex is isoelectric in lead V5 or V6.