I. Correlation of electrocardiographic and pathologic findings in anteroseptal infarction

Abstract The findings in the Wilson precordial leads and in the standard and Goldberger limb leads have been correlated with the pathologic findings in 161 cases in which myocardial infarction was definitely established and accurately localized at autopsy. The cases have been classified in accordance with the anatomic location of the infarct into the following seven groups: anteroseptal, large anterolateral, anteroposterior, septal, posterior, posterolateral, and lateral, When classification into more than one category was possible, because of the large size or multiplicity of the infarct found at autopsy, the lesion of principal electrocardiographic interest became the determining factor. This communication comprises a study of the electrocardiographic and pathologic findings in twenty cases of anteroseptal infarction. In the majority, the infarct was confined to a relatively narrow strip of the free anterior wall and the contiguous anterior portion of the interventricular septum. Serial electrocardiograms taken during the acute phase are presented in six cases and include a control tracing antedating the infarct in four cases, and one or more records after healing in four cases. Single electrocardiograms obtained during the stage of injury are presented in eight additional cases. The remaining six cases came under study after the infarct was completely healed. In fourteen cases, the infarct involved the apical one-third to two-thirds of the anteroseptal wall of the left ventricle. The electrocardiogram in eight of these cases was characterized by a normal initial R wave in Lead V 1 and an abnormal QR or QS complex in one or more of the next three leads (V 2 , V 3 , and V 4 ). The Q wave of a QR complex was considered abnormal when the time interval from its onset to nadir exceeded .02 second and when its amplitude was more than 25 per cent of the voltage of the succeeding R. The electrocardiogram in five of the fourteen cases displayed a QS complex in Leads V 1 and V 2 , as well as an abnormal initial downward deflection in Lead V 3 or V 3 and V 4 . In four of these five cases, the QS complexes in Leads V 1 and V 2 were accompanied by abnormal elevation of the RS-T segment and could be correlated with extension of the infarct into the septum. The electrocardiogram of the last case in the group displayed marked RS-T displacement in Leads V 2 , V 3 , and V 4 without significant abnormalities in the initial phase of the QRS complex. The registration of an R wave in place of a Q wave in these leads could be correlated with the patchy distribution of the infarct through the anteroseptal wall. In two cases, the infarct was centered in the middle one-third of the anteroseptal wall and did not reach either the apex or base. The tracing of one of these displayed a normal initial R wave in Lead V 1 and an abnormal QR or QS complex in the next three leads. Serial changes in the T waves of Leads V 2 and V 3 without significant QRS abnormalities were observed in the other case during the acute stage of an anteroseptal infarct, which subsequently proved to be small in size and intramural in location. The infarct was located in the basal one-third of the anteroseptal wall in the four remaining cases and was manifested by an abnormal QR or QS pattern together with abnormal RS-T displacement confined to the first two or three precordial leads. Extension of the infarct into the basal one-third of the interventricular septum was demonstrated in three of these cases and may have been partly or wholly responsible for the QRS-T abnormalities in Leads V 1 and V 2 . Definitely abnormal Q waves were not found in Leads V 5 or V 6 in any case where the infarct was confined to the anteroseptal wall, but borderline QR complexes were recorded in these leads in two cases and were attributed to reference of the potential variations of the anteroseptal infarct toward the axilla as a result of clockwise rotation of the heart on its longitudinal and anteroposterior axes. Diagnostic signs of anterior infarction were found in the standard limb leads in only two of the twenty cases. These three leads, together with a single precordial lead, would have been inadequate for diagnostic purposes in the majority of the cases in this series and would have been insufficient for localizing purposes in all cases. On the other hand, multiple precordial leads furnished adequate evidence in all cases for a positive or presumptive diagnosis of myocardial infarction and for a clinically satisfactory prediction of the position of the lesion.