Electrocardiographic Lead-Tensor Measuring System

An instrument for automatic measurement of the electrocardiographic lead tensors in a human torso model has been developed. Potential is measured and recorded at 427 points on a sphere within the model and from these data the spherical harmonics of the potential function and the components of the lead tensors are computed. The system can also be used for general purpose potential measurement in small electrolytic tanks. A stepping motor drives a radial arm in elevation and azimuth and a probe suspended vertically from the arm dips into the neck of the model. The potential is measured by two servo-driven bridge circuits and is simultaneously recorded on a strip chart and entered in numerical form on punched cards. Scale expansion is available when measuring fields of low gradient.