Use of the sinus P wave in diagnosing electrocardiographic limb lead misplacement not involving the right leg (ground) lead

No general approach has been established for the diagnoses of the various t ypes of electrocardiograms of limb lead misplacement not involving the righ t leg (ground) lead. We have developed a 3-step algorithm for such differen tial diagnosis that can be applied without having re, rely on the compariso n with a reference electrocardiogram. It is based on the observation that t he frontal plane sinus P vector loop is almost invariably inscribed counter clockwise. The 5 types of electrocardiograms of limb lead misplacement can be differentiated according to the P wave axis, the location of the lead aV R in the electrocardiogram, and specifically any apparent reversal of the d irection of inscription of the frontal plane P vector loop due to lead misp lacement. Characteristic limb lead P wave patterns provide 6 signs capable of inferring from the electrocardiogram alone the direction of inscription about 94% of the time. P wave axis itself is diagnostic in an additional 4% .