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 types of electrocardiograms of limb lead misplacement not involving the right leg (ground) lead. We have developed a 3-step algorithm for such differential diagnosis that can be applied without having re, rely on the comparison with a reference electrocardiogram. It is based on the observation that the frontal plane sinus P vector loop is almost invariably inscribed counterclockwise. The 5 types of electrocardiograms of limb lead misplacement can be differentiated according to the P wave axis, the location of the lead aVR in the electrocardiogram, and specifically any apparent reversal of the direction of inscription of the frontal plane P vector loop due to lead misplacement. 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%.