3. WWhhaatt iiss tthhee EECCGG
An electrocardiogram
(ECG or EKG) is a
recording of the
electrical activity of the
heart over time
produced by an
electrocardiograph,
A noninvasive 11/03/14
machine
20. PPrriinncciipplleess ooff hheeaarrtt EECCGG rreeccoorrddiinngg
(1) An electrical
force directed
twoards the (+)
pole of a lead
results in an
upward
deflection on
the EKG
recording of
that lead
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24. (3) an elcterical forces directed
perpendicular to ECG lead does not
register any activity by that lead,
or it can be bi-phasic ( equi-phasic )
( a “ flat line on the recording )
11/03/14
26. (4) The magnitude of
the deflection either
upward or downward ,
reflects how parallel
the electrical forces
is to the axis of the
lead being examined .
The more parallel to
the lead the greater
the magnitude of the
deflection
11/03/14
33. EECCGG iinntteerrpprreettaattiioonn
1. Heart rhythm
2. Heart rate
3. Intervals ( PR , QT , ST )
4. Mean QRS axis
5. P wave abnormalities
6. Abnormalities of QRS
7. ST and T wave abnormalities
11/03/14
34. 11)) HHeeaarrtt rrhhyytthhmm
Sinus rhythm
every P wave is
followed by a QRS
every QRS is
preceded by a P
wave
P wave is upward in
lead I , II , III
if not Arrhythmia
11/03/14
38. 22)) HHeeaarrtt rraattee
Heart rate = 25mm/sec times 60sec/min
No of mm b/w beats
If the distances are regular, count the
number of "little boxes" from the beginning of
one QRS to the beginning of the next QRS
complex.
Divide the number of "little boxes" (which each
represent 0.04 seconds) into 1500 to obtain
the heart rate in beats per minute.
11/03/14
41. RRuullee ooff 330000
Take the number of “big boxes”
between neighboring QRS
complexes, and divide this into
300.
The result will be approximately
equal to the rate
11/03/14
51. MMeemmoorriizzee tthheessee pprriinncciipplleess
In right ventricular hypertrophy
there is always inversion of the
normal
In the left ventricular hypertrophy
there is exaggeration of the
normal
11/03/14
