Although the electrocardiograph has been much used in the diagnosis of the arrhythmias and of myocardial disease, yet the use of the information which it gives in regard to the hypertrophy of the various chambers of the heart has been considerably neglected. It is my present aim to call attention to this information and to show how it can be made use of in the examination of the heart, and especially to show of what value it may be as an aid in the diagnosis of valvular lesions.
Each valvular lesion leads to the hypertrophy of one or more of the chambers of the heart, and this hypertrophy has an effect on the electrocardiogram of the individual. Hypertrophy of the auricle is shown by an increase in the height of the wave P, over 2 mm., as seen in Figure 1, being abnormal. Hypertrophy of the right ventricle is also