ECG

1. ECG
1
Dr Majid Shojaee
Assisstant Professor of Emergency Medicine
 Shahid Beheshti university of medical sciences
Dr Majid Shojaee

2. Leads 1,2,3,aVR,aVL,aVF
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3. Limb leads & colours
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4. Euro & Iran
Rt Lt
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5. Dr Majid Shojaee 5

6. Precordial Leads= V1-V6
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7. Precordial Leads
 Measure potentials close to the heart, V1-V6
 Unipolar leads
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8. ECG Chest Leads
Precardial (chest) Lead Position
 V1 = 4th ICS, right sternal border
 V2 = 4th ICS, left sternal border
 V3 = between V2 and V4
 V4 = 5th ICS, left Mid clavicular Line
 V5 = 5th ICS Left anterior axillary line
 V6 = 5th ICS Left mid axillary line
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9. Calibration, or standardization
 refers to the amplitude of the waveforms on the
tracing. It is usually set at a default value of 10
mm/mV
Increasing the calibration to 20 mm/mV is helpful
when trying to decipher P wave morphology.
 Decreasing the calibration to 5 mm/mV is helpful
in cases wherein the amplitude of the QRS
complex (usually in the precordial leads) is so
large
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10. Paper speed
 usually is set at a default of 25 mm/sec. It may
be manipulated for purposes of deciphering a
dysrhythmia,
 It is important that the clinician examine all
ECG tracings for standardization and speed
parameters before attempting clinical
interpretation.
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11. ADDITIONAL lEADS
 15 lead ECG
 Posterior leads
 Right leads
 Invasive procedural leads
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12. 15 leads: V7-V8-V9
V7: post. Axillary line
v8: tip of Lt scapula
v9: near the border of
paraspinal m.
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13. Posterior leads
 V8-V9
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14. Right side leads; V4R (Rt 5th intercostal
space mid-clavicular line) is the most useful lead for
detecting STE in RV MI
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15. Lewis leads RA &LL
Vertical sternal (Barker) leads RA &LL
Modified bipolar chest leads (MCL)
MCL1: RA & LA
MCL6: RA & LL
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Alternative leads
Dr Majid Shojaee

16. WHY?
 Rhythm assessment often requires ECGmonitoring
over continuous periods of time,
 making the standard 12-lead ECG (requiring 10
electrodes), and
 even unipolar precordial V1 monitoring (requiring
5 electrodes), not feasible.
 A number of alternative lead systems requiring
fewer electrodes have been described.
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17. &
 vertical sternal leads produce a
larger P wave than other
systems
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18. Einthoven’s triangle
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19. Lewis, Barker & MCL6 : lead 2
MCL1: lead 1
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23. Einthoven’s triangle
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24. Lead misplacement
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25. Normal ECG Signal
 P – atrial
depolarization
 QRS complex –
ventricular
depolarization
 T – ventricular
repolarization
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26. Reading 12-Lead ECGs
The best way to read 12-lead ECGs is : 6-step approach:
1. Calculate RATE
2. Determine RHYTHM
3. Determine QRS AXIS
4. Calculate INTERVALS
5. Assess for HYPERTROPHY
6. Look for evidence of INFARCTION
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27. Rate Determination
300/RR(large square)
40
Next
QRS
QRS
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28. Rhythm
 Sinus?
 Each P followed by QRS, R-R constant
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30. Rate Rhythm Axis Intervals Hypertrophy
Infarct
We can quickly determine whether the QRS axis is normal by
looking at leads I and II.
If the QRS complex is
overall positive (R > Q+S)
in leads I and II, the QRS
axis is normal.
QRS negative (R < Q+S)
QRS equivocal (R = Q+S)

31. Rate Rhythm Axis Intervals Hypertrophy
Infarct
Now using what you just learned fill in the following table. For example, if the
QRS is positive in lead I and negative in lead II what is the QRS axis? (normal,
left, right or right superior axis deviation)
44
120o
-150o
90 120 o o
-30o
0o
30o
-60o
60o
-90o
-120o
90o 120o
180o
150o
QRS Complexes
I
I II Axis
+ + normal
II
Dr Majid Shojaee

32. Rate Rhythm Axis Intervals Hypertrophy
Infarct
Now using what you just learned fill in the following table. For example, if the
QRS is positive in lead I and negative in lead II what is the QRS axis? (normal,
left, right or right superior axis deviation)
45
120o
-150o
90 120 o o
-30o
0o
30o
-60o
60o
-90o
-120o
90o 120o
180o
150o
QRS Complexes
I
I II Axis
+ +
+ -
normal
left axis deviation
II
Dr Majid Shojaee

33. Rate Rhythm Axis Intervals Hypertrophy
Infarct
… if the QRS is negative in lead I and positive in lead II what is the QRS axis?
(normal, left, right or right superior axis deviation)
46
120o
-150o
90 120 o o
-30o
0o
30o
-60o
60o
-90o
-120o
90o 120o
180o
150o
QRS Complexes
I
I II Axis
+ +
+ -
- +
normal
left axis deviation
right axis deviation
II
Dr Majid Shojaee

34. … if the QRS is negative in lead I and negative in lead II what is the QRS axis?
(normal, left, right or right superior axis deviation)
-30o
0o
30o
-60o
60o
Rate Rhythm Axis Intervals Hypertrophy
Infarct
-90o
-120o
-150o
90 120 o o
180o
150o
47
QRS Complexes
I
I II Axis
+ +
+ -
- +
- -
normal
left axis deviation
right axis deviation
right superior
axis deviation
120o
90o 120o
II
Dr Majid Shojaee

35. Rate Rhythm Axis Intervals Hypertrophy
Infarct
Is the QRS axis normal in this ECG? No, there is left axis
deviation.
The QRS is
positive in I
and negative
in II.

36. Axis Determination
49
ALL UPRIGHT
NORMAL RIGHT LEFT
Dr Majid Shojaee

37. Intervals
 QT= 0.33”-0.42” (<0.47”) QTc=QT/√RR
 QRS <0.12”
 PR =0.10”-0.20”
 P duration < 0.12 sec
P amplitude < 2.5 mm
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38. Hyperthrophy / Enlargement
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39. Right Atrial Enlargement
 Always examine Lead 2 for RAE
 Tall Peaked P Waves, Arrow head P waves
 Amplitude is 4 mm ( 0.4 mV) - abnormal
 Pulmonary Hypertension, Mitral Stenosis
 Tricuspid Stenosis, Regurgitation
 Pulmonary Valvular Stenosis
 Pulmonary Embolism
 Atrial Septal Defect with L to R shunt
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40. Right Atrial Enlargement
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P wave voltage is 4 boxes or 4 mm
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41. Left Atrial Enlargement
 Always examine V 1 and Lead 1 for LAE
 Biphasic PWaves, Prolonged P waves
 P wave 0.16 sec, ↑ Downward component
 Systemic Hypertension, MS and or MR
 Aortic Stenosis and Regurgitation
 Left ventricular hypertrophy with dysfunction
 Atrial Septal Defect with R to L shunt
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42. Left Atrial Enlargement
55
P wave duration is 4 boxes-0.04 x 4 =
0.16
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43. Atrial Hypertrophy: Enlarged Atria
RIGHT ATRIAL HYPERTROPHY
Tall, peaked P wave in leads I and II
LEFT ATRIAL HYPERTROPHY
Wide, notched P wave in lead II
Diphasic P wave in V1
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44. Ventricular Hypertrophy
 Ventricular Muscle
Hypertrophy
 QRS voltages in V1 and
V6, L1 and aVL
 We may have to record to
½ standardization
 T wave changes opposite
to QRS direction
 Associated Axis shifts
 Associated Atrial
hypertrophy
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45. Marriott's Practical Electrocardiography:
Galen S. Wagner
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46. Normal Variations in ECG
 May have slight left axis due to rotation of heart
 May have high voltage QRS – simulating LVH
 Mild slurring of QRS but duration < 0.09
 J point depression, early repolarization
 T inversions in V2, V3 and V4 – Juvenile T ↓
 Similarly in women also T↓
 Low voltages in obese women and men
 Non cardiac causes of ECG changes may occur
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47. S.A.H. ECG changes
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48. ?
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49. Pediatric ECG
 This is the ECG of a 6 year old child
 -Heart rate is 100 – Normal for the age
 -See )V1 + V5( R >> 35 – Not LVH – Normal
 -T↓ in V1, V2, V3 – Normal in child
 -Base line disturbances in V5, V6 due to
movement by child
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