Everyone is familiar these days with the electrocardiogram, known by the acronym
ECG or EKG (US style, which comes from the German spelling). This is an
invaluable medical test to show the electrical conductivity of the heart, which
in turn can give the doctor an idea of the health of the heart muscle itself.
Many think of this as one of the newer developments in medical science, but it
is not, having a history dating back to the mid 1600s.
In 1664, Jan Swammerdam, a Dutchman, disproved Descartes’
previous mechanical theory of animal motion by removing the heart of a living
frog and showing that it was still able to swim. On removing the brain all
movement stopped. (This reminded me of the professor who proved that fleas heard
through their legs. When he told intact fleas to jump they did - but after he
removed the legs they no longer moved, proving they must have previously heard
through their legs.)
Almost 200 years later, in 1856, researchers Kolliker and
Muller accidentally discovered the electrical activity of the heart when a frog
sciatic nerve and leg muscle preparation fell onto an isolated frog heart and
both muscles contracted synchronously.
The investigation into the electrical stimulation of muscles
continued, with the main stumbling block being the difficulty in measuring such
small voltages. However, in 1887, Augustus Waller, working in St Mary’s Medical
School, London, published the first human electrocardiogram, having recorded the
electrical activity of the heart of a Thomas Goswell, a technician in the
laboratory. This required not only wires, but the subject sitting with his hands
in glass jars of salt solution. Waller’s electrocardiograph machine consisted of
an electrometer fixed to a projector. The trace from the heartbeat was enlarged
by projecting it on to a photographic plate which in turn was fixed to a toy
train, to produce a graphical, moving record! Unfortunately Waller did not see
the clinical application of his EKG.
Two years later, in 1889, Dutch physiologist Willem Einthoven
saw Waller demonstrate his technique at the First International Congress of
Physiologists in Bale. Waller often demonstrated by using his dog “Jimmy”
patiently standing with his paws in glass jars of saline, and began to develop
the technique further.
What Einthoven, who was working in Leiden, did was to throw
away the toy train and use a different and much more sensitive string
galvanometer that he had invented himself in 1901. The different wave formations
could be more easily identified, and it was Einthoven who assigned the letters
P, Q, R, S and T to the various deflections, and described the
electrocardiographic features of a number of cardiovascular disorders, such as
atrial fibrillation.
In 1909, Thomas Lewis of University College Hospital, London
bought an Einthoven string galvanometer and published a paper in the BMJ
detailing his careful clinical and electrocardiographic observations of atrial
fibrillation. Lewis identified a fibrillating horse using the string
galvanometer’s electrocardiogram recording, and then followed the horse to the
slaughterhouse where he could visually confirm the fibrillating atrium.
By 1924, the EKG, in a form close to that we know today was
developed by Einthoven, who that year was awarded the Nobel Prize in Medicine
for his discoveries.
Since then, the EKG has become even more sophisticated, and
the equipment much smaller in size. However, it was not until 1963 that we began
to carry out EKGs while making the heart work. This exercise ECG concept was
promoted by Robert Bruce and colleagues to describe their multistage treadmill
exercise test later known as the Bruce Protocol. “You would never buy a used car
without taking it out for a drive and seeing how the engine performed while it
was running, and the same is true for evaluating the function of the heart,” he
is rumored to have said.
So where does the famous spy Mata Hari come in? Well,
somewhat tenuous I know, but Mata (1876-1917) lived in Leiden as a young girl
when Einthoven (1860-1927) was doing his experiments there. Who knows, she might
have electrically stimulated young Willem as well as her other later exploits
which led her to the firing squad!
