True Z8.1e, Owner'S Manual

Page: 33 / 173

Understanding the ECG Signal
T
HE
D
ISPLAY
Z 8 . 1 e E l l i p t i c a l O w n e r ’ s G u i d e
33
The various shapes in an ECG are a side-
effect of the electrical control signals
the heart generates to fire its muscles in
the right sequence. The signals start in
the upper-right part of the heart known
as the sinoatrial node, then travel down
to the lower-left part of the heart known
as the Purkinje fibers. In between these
two points, the electrical signals are
received, paused, modified, or forwarded
by three other important control nodes:
Bachmann's bundle, the bundle of His,
and the left & right bundle branches.
This complex electrical signal causes the
atriums (small chambers) and ventricles
(large chambers) to contract in a
controlled rhythm to pump blood to the
body and lungs. This rhythm and the
repeating ECG waveform associated with
it are measured as the heart rate.
T
HE
D
ISPLA
Y
Why not E "K" G?
The electrocardiograph
(the device which pro-
duces the electrocardio-
gram) was invented by
Dutch physiologist Willem
Einthoven between 1895
and 1903, for which he
received the Nobel Prize
in Medicine in 1924.
Since all his scientific
papers were published in
German, the ECG concept
was introduced to the
world as the German
construct "electroKardio-
gramm," and thus the
abbreviation "EKG." The
correct English terms are
electrocardiograph
(graph is "diagramm" in
German) and ECG.
"EKG" was common in
English communication
for many decades after
the introduction of the
electrocardiograph, espe-
cially in informal use. It
appears that around the
early 1980s the correct
"ECG" became more com-
mon.
<www.ecglibrary.com/
ecghist.html>
U
NDERSTANDING
T
HE
ECG
S
IGNAL