Electrocardiogram

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2. ECG
• Interpretation of
the electrical activity of
the heart over a period of time
• Electrical manifestation of the
activity of the heart. Recorded
with surface electrodes on the
limbs or chest.
• ECG is used to measure the rate
and regularity of heartbeats, the
presence of any damage to the
heart.
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5. ECG is detected by Einthoven's triangle
method
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6. THE HEART
• It is a 4 chambered muscular
organ consist of 2 atriums
and 2 ventricles.
• It function in a regular
fashion to pump blood
thought the body.
• Average heart rate of a
human being is 72beats/min
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7. • SA node- sinoartial
node- acts like a
function generator,
called pacemaker of
heart
• AV node-
artioventricular node-
acts like a delay device
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9. HEART WAVES
QRS
P wave- SA
wave- cumulati
node
Time ve
genetrated, du Amplitude- 0.1 Amplitude- Time duration-
duration- 60-8 repolarization
e to to 0.2 mV 1mV 80ms
0ms of atria &
contraction of
depolarization
atria.
of ventricle.
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10. T wave-
repolarization of
ventricle
Amplitude- Amplitude-
0.01mV 0.3mV
U wave- after
Time duration-
potential in
120-160ms
ventricle
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12. DETECTION OF QRS EVENT
Using PAN tompkins Recognises QRS on
the bases of
algorithm
slope, width, amplitude
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13. Band-pass filter
In order to
attenuate noise Attenuates low
the signal is frequency of P &
passed through a T waves, baseline
bandpass filter, drift, high
composed of a frequencies of
high pass filter EMG and power
and a low pass line interference
filter.
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15. High pass It has a DC
filter gain of 32
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16. Differentiation
In differentiation, technique
for finding slopes that
distinguish QRS wave from
other ECG wave.
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18. Squaring
Makes all data
Point-by-point
positive and
squaring of the
accentuates higher
signal samples
frequencies (QRS)
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20. Adaptive thresholding
Adaptive thresholding
It updates the peak
is done on the basis
level & noise level
of BPF waveforms &
and determine if it is a
moving-window
QRS event or not
integral
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21. Artifacts in ECG
High
frequency
noise
Wandering
base line
Power line
interference
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22. High frequency noise
Maybe formed by instrumentation
amplifier, recording device or
electrodes may pickup ambient EM
signals by cables
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23. Power line interface
Odd harmonics are
Maybe formed if ECG
generated which would be
signal is not properly
represented as spikes on
sinusoidal
ECG waveform
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24. Wandering Base line
Isoelectric line is not fixed,
noise in the signal
Patient needs to be
Also known as motion
static, electrodes should
artifact
be clean
Maybe arise due to patient
movement, movement of
external source, patient
body’s (inside) movement.
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