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Synopsis
Previous research demonstrated the presence of a range of varying low frequency potentials
on the surface of the human body covering a range of 10 to 2000 c/s. It was shown
that a large part of these varying potentials originated from the activating wave
of potential. Normally this wave of potential is recorded as an electrocardiogram.
The QRS part of the electrocardiogram may be triangular, diphasic, M shape, etc.,
and has for many years been chiefly recorded by the Einthoven String Oscillograph
of comparatively high inertia. Of recent years attention has been drawn to improved
recording by C.R.O. or moving coil oscillograph. The usual custom with C.R.O. recording
is to suppress higher frequencies in order to produce a smoother recording. This research
demonstrated that the QRS wave contains a large range of higher frequencies of a variable
nature which cannot be normally observed in detail in the ordinary recording, but
which can be selected and observed by methods of electronic wave analysis. It is shown
that undistorted recording necessitates careful attention to technical details and
requires special amplifier circuits of which one developed for this research is given.
Examples of clinical recordings are given, including the oscilloscope recording of
the frog's heart with the changes in the anlaysis form during the action of a drug.
The application of a mechanical photo-electric source for an artificial patient as
suggested by Robertson is made use of and elaborated, while the value of this method
for other electronic tests is shown.
