Transcript ECG diagnosis - Emed

ECG diagnosis
Aims
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10 ECG rules
ECG signs of M.I.
Evolution of changes in M.I.
Classical Appearences
QRS waveform nomenclature
R
r
qR
qRs
Qrs
QS
Qr
Rs
rS
qs
rSr’
rSR’
The 10 rules for a normal ECG
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
.2
Rule 1
1.0
Millivolts
0.5
R
PR
interval
PR interval should be 120 to
200 milliseconds or 3 to 5 little
squares
T
P
Q
0
S
-0.5
0
200
400
Milliseconds
600
Rule 2
1.0
R
The width of the QRS complex
should not exceed 110 ms, less
than 3 little squares
Millivolts
0.5
T
P
Q
0
S
-0.5
QRS
0
200
400
Milliseconds
600
Rule 3
I II III
aVR aVL aVF
The QRS complex should be
dominantly upright in leads I and II
Rule 4
I II III
aVR aVL aVF
QRS and T waves tend to have the
same general direction in the limb
leads
Rule 5
All waves are negative in lead aVR
P
T
Q
S
Rule 6
V1
V2
V3
V4
V5
V6
The R wave in the precordial leads must grow from V1 to at least V4
Rule 7
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The ST segment should start isoelectric except in V1 and
V2 where it may be elevated
Rule 8
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The P waves should be upright in I, II, and V2 to V6
Rule 9
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
There should be no Q wave or only a small q less than
0.04 seconds in width in I, II, V2 to V6
Rule 10
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The T wave must be upright in I, II, V2 to V6
Characteristic changes in AMI
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ST segment elevation over area of damage
ST depression in leads opposite infarction
Pathological Q waves
Reduced R waves
Inverted T waves
ST elevation
• Occurs in the early stages
R
ST
P
Q
• Occurs in the leads facing the
infarction
• Slight ST elevation may be
normal in V1 or V2
Deep Q wave
• Only diagnostic change of
myocardial infarction
R
ST
• At least 0.04 seconds in duration
P
T
Q
• Depth of more than 25% of
ensuing R wave
T wave changes
• Late change
R
• Occurs as ST elevation is
returning to normal
ST
P
• Apparent in many leads
T
Q
Bundle branch block
Anterior wall MI
I II III
aVR aVL aVF
Left bundle branch block
V1 V2 V3
V4 V5 V6
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Sequence of changes in evolving AMI
R
R
R
ST
T
ST
P
P
Q S
P
T
Q
Q
1 minute after onset
1 hour or so after onset
A few hours after onset
R
ST
P
ST
P
T
Q
A day or so after onset
T
P
T
Q
Later changes
Q
A few months after AMI
Anterior infarction
Anterior infarction
I II III
Left
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Inferior infarction
Inferior infarction
I II III
Right
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Lateral infarction
Lateral infarction
I II III
Left
circumflex
coronary
artery
aVR aVL aVF
V1 V2 V3
V4 V5 V6
Location of infarct combinations
I
aVR
LATERAL
aVL
II
V1
ANT
POST
V2
V4
ANT
SEPTAL
V5
ANT
V3
III
INFERIOR
aVF
V6
LAT
Diagnostic criteria for AMI
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Q wave duration of more than 0.04
seconds
Q wave depth of more than 25% of
ensuing r wave
ST elevation in leads facing infarct (or
depression in opposite leads)
Deep T wave inversion overlying and
adjacent to infarct
Cardiac arrhythmias