A Novel Vectorcardiogram System
  This paper presents the proof-of-concept investigation for a miniaturized vectorcardiogram [VCG] system for ambulatory on-body applications that continuously monitors the electrical activity of the heart in three dimensions. We investigate the minimum distance between a pair of leads in the X, Y and Z axes such that the signals are distinguishable from the noise. The target dimensions for our VCG are 3x3x2 cm and, based on our preliminary results, it is possible to achieve these dimensions. The next step in our research is to build the miniaturized VCG system that includes processing, learning and communication capabilities. 
Gabriel E. Arrobo, Calvin A. Perumalla, Yang Liu, Thomas P. Ketterl,   Richard D. Gitlin, Peter J. Fabri
physics.med-ph