Spatial Magnitude Electrocardiogram in Normals and Myocardial Infarctions: Clinical Usefulness of Spatial Magnitude ECG in the Diagnosis of Old Myocardial Infarctions

QRS waves of the spatial magnitude ECG of 70 normal young men and 127 cases of old myocardial infarctions were examined quantitatively. QRS waves of the normal spatial magnitude ECG showed definite patterns and were classified in 5 groups, namely simple triangular configurations (Type A), small notch at the initial (Type B), at the terminal (Type C) or at the both portions (Type D) of the main QRS waves and with large terminal notch (Type E). Among them Type D was considered as the basic pattern of the normal spatial magnitude ECG. QRS waves of the spatial magnitude ECG changed characteristically in old myocardial infarctions. These abnormal findings consisted of increase of the amplitude and duration of initial notch, slow ascent of ascending limb, prolongation of peak time, decrease of peak magnitude, splitting of QRS waves and increase of the amplitude and duration of terminal notch. These abnormalities were seen in 79.5% of whole cases of infarctions. Abnormalities of QRS waves of infarction type of the spatial magnitude ECG were observed in 67.9% of old myocardial infarctions, whose conventional ECG became less prominent so as not to satisfy the criteria of abnormal Q wave described by Massie et al. with the advancement of recovery process. It was considered that the sequential curves of the changes of the spatial magnitudes of QRS vectors, which had not been taken as to be important previously, had very important diagnostic informations for myocardial infarctions and that the spatial magnitude ECG was very useful for the diagnosis of old myocardial infarctions or latent myocardial injuries whose conventional ECG showed only equivocal changes.