The Normal Apex Cardiogram

T HE apex cardiogram was described in 1878 by Marey.' With the exception of its utilization in the timing of the opening snap of the mitral valve 2 3 and in the identification of the third and fourth heart sounds,4-6 it has been used only infrequently as an aid in timing cardiac phenomena. Technical difficulties in its recording have obstructed its more universal application and, more particularly, its use in timing systolic events of the cardiac cycle. There is no general agreement about the meaning of the apex cardiogram. It is still argued whether the tracing represents the recording of lowfrequency vibrations of the precordium or of the actual movements of the heart.3 7-9 Furthermore, the normal configuration of the systolic wave of the apex cardiogram has not been determined with certainty. If a normal "systolic pattern" were established, deviation from this might be helpful in assessing certain pathophysiologic states. It is the purpose of this report to analyze the normal configuration of the systolic wave of the apex cardiogram by comparing the apex cardiogram with the simultaneous