The Recognition of Strictly Posterior Myocardial Infarction by Conventional Scalar Electrocardiography

Abstract

This study was undertaken in order to determine whether the standard scalar electrocardiogram contains sufficient information to permit the recognition of strictly posterior myocardial infarction. Sixteen patients were selected on the basis of vectorcardiographic evidence and four on the basis of autopsy evidence. One hundred normal adult electrocardiograms served as controls. The data indicate that strictly posterior infarction causes (1) R waves of 0.04 second in V 1 and in contiguous right anterior chest leads with upright T waves and, in the acute phase, ST-segment depressions, (2) Q waves of 0.04 second in an area posteriorly between the spine and the left scapula, (3) R/S ratios equal to or greater than one in V 1 and V 2 , (4) slurring of the descending limb of the R wave in lead V 1 due to abrupt change in QRS direction, and (5) no pathologic Q waves in the standard 12 leads unless diaphragmatic or lateral infarction coexists. Extra chest leads derived from the right anterior and left posterior thorax serve principally to corroborate the diagnoses. R waves of 0.04 second or R/S ratios equal to or greater than one in lead V 1 were also found in the normal child, complete right bundle-branch block, the Wolff-Parkinson-White syndrome with an anteriorly directed delta wave, right ventricular hypertrophy, and an occasional normal adult especially with vertical frontal plane electrical axis. Attention to these differential diagnoses and to the foregoing manifestations of strictly posterior infarction facilitate its recognition by conventional scalar electrocardiography.