Low voltage of the QRS waves in the electrocardiogram, with especial reference to lead IV

Abstract

Analysis was made of 300 cases showing low voltage of the QRS complexes of the elecrtrocardiogram. Three groups of 100 cases each were compared with one another; Group 1 having low voltage of QRS in the classical leads but normal voltage in the precordial (fourth) lead, Group 2 having low voltage of QRS in the fourth lead alone, and Group 3 having low QRS complexes in all four leads. Evidence of heart disease was found in only 57 per cent of the entire series, and only 47 per cent of the group with low voltage in the chest lead alone had evidence of heart disease. Generalized debilitating diseases, changes in the position of the heart, series, and only 47 per cent of the group with low voltage in the chest lead alone had evidence of heart disease. Generalized debilitating diseases, changes in the position of the heart, and changes in the conductivity of adjacent tissues seemed to be important factors in the production of low voltage of the QRS complexes. Furthermore, the thickness of the chest wall and the position of the precordial electrode influenced the voltage of QRS in Lead IV. Heart disease was of no greater relative importance than extracardiac factors in cases showing extreme reduction in ARS voltage (for instance, 0.3 mv. or less). However, in such cases the responsible factor was likely to be more obvious than in cases with moderate degrees of low voltage. Analysis of the literature likewise indicates the importance of the factors mentioned above. Even in the patients with considerable heart disease, fluctuations in the voltage, with changes in the state of compensation, suggested that the heart lesions were of less importance than the secondary manifestations of heart failure in the production of lowered potential. Ten per cent of the entire series showed no evident explanation of any sort for the occurrence of low voltage, being apparently healthy normal persons in every respect. Our study indicates that the solitary finding of low voltage of the QRS complexes is of little or no diagnostic value regarding the presence or absence of heart disease or of any other trouble. The wider use of electrocardiograms on normal people outside of hospitals will probably show a higher incidence of low voltage than the literature suggests at present.