The three bipolar leads (I, II, and III) of the 12-lead electrocardiogram are subject to technical errors that not only confound interpretation but may lead to faulty clinical actions. And while some errors are readily recognized, even experienced electrocardiographers overlook others. Of the 24 permutations of the four limb cables, only 12 are recognizable: 1 normal and 11 lead misplacements, consisting of 3 lead reversals, 2 rotation errors, and 6 ground lead misplacements. These 11 lead errors can be differentiated by combining four critical features: (1) the relationship of lead aVR withV6, (2) recognition of “true” aVR, (3) the morphology and orientation of the P wave, (4) the atrial activation sequence.
Conclusion From these four, an algorithm can be constructed which is a generally useful method to deduce erroneous lead configurations.