Electrocardiographic patterns resulting from improper connections of the right leg (ground) cable

The patterns resulting from improper connections of the right leg (ground) cable to the right arm, left arm, and left leg electrodes (hardly ever discussed in books dealing with electrocardiography) are presented and their genesis is explained. Knowledge about this technical error is important because it: (1) may be misinterpreted as resulting from switching the right arm and left arm cables; and, worse, (2) may not be recognized, which, in patients with abnormal electrocardiograms, can lead to clinically significant errors in interpretation.