THE SUBSTITUTION OF A TETRAHEDRON FOR THE EINTHOVEN TRIANGLE

T HE early studies of the electrical phenomena associated with the human heartbeat carried out by Waller and by Einthoven and his associates led to the adoption of the leads from the two arms and the left leg which are still in universal use. For a great many years little thought was given to the possi-bility that these leads might be entirely inadequate in certain respects and that great progress in electro~rdiographic diagnosis might be achieved by supple.. menting them with leads of other kinds. Some fifteen years ago, however, it became evident that leads in which one electrode is placed on the precordium and the other on some part of the body much farther from the heart are, to some extent, similar to unipolar leads from the ventricular surface, such as were used by Lewis and Rothschild, ’ and are capable of yielding information which limb leads cannot give. In the last decade, precordial leads have become indispensable. This sequence of events raises the question as to whether further important advances in electrocardiography are likely to result from the development of still other new leads. If, like our predecessors, we may be overlooking oppor-tunities in this direction, it is worth while to examine our present situation in th