Effect of VCG sensitivity to dipole content in detecting infarctional changes

Abstract

The axial, the Frank, and the cube vectorcardiographic (VCG) lead systems have been examined for fidelity of reporting the dipolar component while excluding the non-dipolar component of surface potential records. Recordings were made from 142 sites on the chest of 28 normal young men, 19 men one month after an acute inferior infarction and 22 men one month after an acute anteroseptal infarction. The authors capitalized on the fact that the VCG is the dipole moment loop which has been altered by the particular recording system used in 3 distinct fashions: attenuation, dipolar distortion, and nondipolar inclusion. If an arbitrary value of 1 is assigned to the actual loop of dipole moment, the magnitude after attenuation by the clinical VCG falls into this range: axial.71, Frank.57, and cube .35. Dipolar distortion is greates in the cube system, causing the loop shape to move toward diagnosis in the case of inferior infarction, but away from it in anterior infarction. Non-dipolar addition is relatively greatest in the cube, but absolutely greater in the Frank and the axial system. Such inclusion alters the cube appearance toward diagnosis in inferior myocardial infarction, and away from it in anterior infarction. It significantly alters the appearance toward diagnosis in anterior infarction when recording with Frank system. This means of assay capitalizes on the extremely low incidence of false positives characteristic of the loop of dipole moment. It identifies for each instant in each VCG system the biases introduced by the respective system's dipolar distortion and nondipolar inclusion. With this approach it may be possible to specify those biases which increase the level of true positive diagnoses, and those which mainly increase false positivity and should perhaps be discarded.