Experimental studies on the effects of variable antero-posterior distance of the trunk upon ECG and VCG with torso models

The effects of variable antero-posterior distance of the trunk upon standard 12 lead systems and three different corrected orthogonal VCG lead systems were investigated with the reference to the lead vector. Human torso model of an average Japanese adult male and four elliptical cylinders, which had fixed height and left to right distance and variable antero-posterior distance were employed as a homogeneous volume conductor. Lead vectors were measured when the artificial current dipole was placed at each of 15 points in the heart area. The following results were made in the present study. 1) The presence of proximity effect in V1, V2, V3 and V4 leads were demonstrated. These proximity effects were greater value in the models with short antero-posterior distance of the trunk. 2) The normality and orthogonality of the Frank lead system were better than those of the modified Frank lead system in the models with long antero-posterior distance of the trunk. 3) The normality and orthogonality of the modified Frank lead system were better than those of the Frank lead system in the models with relatively short antero-posterior distance of the trunk. 4) The Mc Fee lead system had better orthogonality and worse normality. 5) The effects of variable dipole locations upon the lead vectors measured with each lead systems became considerably greater, according as the shortening of the antero-posterior distance of the trunk.