In the preceding paper1 the use of multiple points over the precordium in obtaining lead IV was discussed. In that paper the findings for patients with normal hearts and for those with various pathologic conditions of the heart and lungs other than myocardial infarction were reported.
A similar study has been made of patients suffering from, or suspected of having, myocardial infarction. The technic was the same as that used in our previous study; i. e., nine designated points over the precordium were employed (see figure 1 in the first paper). If the apex was outside the ninth position an additional tracing was made with the electrode placed directly over the apex of the heart. The positions will be referred to in the future as leads IV1, IV2, IV3, etc. The customary German silver electrodes (11/2 by 2 inches [3.8 by 5 cm.]) were used. The