The Relation of Precordial and Orthogonal Leads

A systematic search was made for the effective axes from an orthogonal lead system that best duplicated the diagnostically significant features of precordial leads. Only one of 240 precordial leads was not matched with a rotated orthogonal lead having the same features judged to be clinically significant. The average rotated lead axes corresponding to precordial leads V 1 through V 6 were systematically located from an axis directed upward and to the right corresponding to V 1 to one directed downward and to the left corresponding to V 6 . The location of these average rotated axes has been presented and the per cent contribution of XYZ leads to each of these axes has been calculated. These results provide a guide to the orthogonal lead location of diagnostic information now obtained from precordial leads.