Secondary R Waves in Right Chest Leads

The use of the electrocardiogram as an aid in the diagnosis of right ventricular hypertrophy is a comparatively recent advance. It has been suggested that an electrode placed in a similar position to V4 but to the right of the sternum (V4R) would be of additional value in that it would record right ventricular patterns more accurately than the present chest leads. We have been recording this lead (V4R) routinely for the last year and have frequently had difficulty in assessing the sig-nificance of the patterns found, mainly because complexes with secondary R waves often occurred in both normal and abnormal tracings. There is no agreed terminology for describing these patterns but the different terms used and the theories underlying them have been comprehensively reviewed by Katz et al. (1950). The complexes have been termed RSR1 or denoted as showing the presence of an " embryonic r wave " or " incomplete right bundle branch block. " A more recent suggestion is that the pattern occurs as the result of " defective intraventricular conduction " which may be " focal " or more widespread (Segers, 1949). The confusion in nomenclature is well illustrated by the term " physiological incomplete right bundle branch block " which aptly reflects the uncertainty as to the significance of this type of pattern. It was decided to record V4R in a series of normal subjects in order to determine the variations