The usual leads employed for electrocardiogram and vectorcardiogram have been introduced not for clearcut relationship between the leads and the electromotive forces of the heart, but rather for their clinical easiness or for their so-called unipolarity. Hence the relationship obtained is so complex that there arose many different interpretations about it. Even vectorcardiogram, as Dr. Johnston and Dr. Prof. Maekawa pointed out, is not the true expression of the electromotive vector of the heart but is merely the vectorical representation of the obtained leads.
We employed the theory of lead field and lead vector and devised a new method to obtain the curves of the time-course of each of three components perpendicular to each other of the composite electromotive vector in the whole heart. We named it “the vectorical lead”. The method is as following: We lead between the nape and both feet with small electrodes, between the front and the back, and the right and the left of the chest with the large plate electrodes which cover the whole projections of the heart to each direction. The lead-fields between these electrodes are approximately homogeneous and parallel through the whole heart and hence each of the three spacial components are obtained correctly.
Comparing the curves by this method with that of the usual leads, we concluded that a VF lead was the head-to-feet component of the electromotive force of the heart, and that the right-angled isosceles triangle schema by Dr. Prof. Maekawa is more proper to the actual conditions than the equilateral triangle schema by Einthoven. The clinical applications of this method will be discussed in the future papers.
