1. ECG Interpretation Criteria Review

2. Axis Deviation RAD = If R wave in III > R wave in II
Left
Right
RAD = If R wave in III > R wave in II
LAD = If R wave in aVL > I; and deep S wave in III

3. Axis Deviation Criteria
LEAD I
LEAD II
(or Lead aVF or III)
Normal
Positive
LAD
Negative
RAD
Intermediate axis

4. Axis Deviation LAD = possible left anterior fasicular block
RAD = possible left posterior fasicular block

5. Right Atrial Abnormality Criteria
Tall P waves in lead II
(or III, aVF and sometimes V1)

6. Left Atrial Abnormality
Lead II (and I) show wide P waves
(second hump due to delayed depolarization of the left atrium)
(P mitrale: mitral valve disease)
V1 may show a bi-phasic P wave
1 box wide, 1 box deep
(biphasic since right atria is anterior to the left atria)

7. Right Ventricular Hypertrophy Criteria
In V1, R wave is greater than the S wave - or - R in V1 greater than 7 mm
Right axis deviation
In V1, T wave inversion (reason unknown)

8. Left Ventricular Hypertrophy Criteria
If S wave in V1 or V2 + R wave in V5 or V6 ≥ 35 mm...
...or, R wave > 11 (or 13) mm in aVL or I...
...or, R in I + S in III > 25 mm.
Also
LVH is more likely with a “strain pattern” or ST segment changes
Left axis deviation
Left atrial abnormality

9. Right Bundle Branch Block Criteria
V1 or V2 = rSR’ - “M” or rabbit ear shape
V5 or V6 = qRS
Large R waves
Right chest leads: T wave inversion (“secondary changes” since they reflect a delay in depolarization not an actual change in depolarization).
Complete RBBB: QRS > 0.12 sec.
Incomplete RBBB: QRS = 0.10 to 0.12 sec.

10. Left Bundle Branch Block Criteria
Wide QRS complex
V1 = QS (or rS) and may have a “W” shape to it.
V6 = R or notched R and may show a “M” shape or rabbit ears
Secondary T wave inversion
Secondary if in lead with tall R waves
Primary if in right precordial leads

11. Incomplete Bundle Branch Blocks
RBBB or LBBB where QRS is between .10 and .12 with same QRS features

12. Left Anterior Fascicular Block
Limb leads
QRS less width less than 0.12 sec.
QRS axis = Left axis deviation (-45° or more)
if S wave in aVF is greater than R wave in lead I
small Q wave in lead I, aVL, or V6

13. Left Posterior Fascicular Block
Right axis deviation (QRS axis +120° or more)
S wave in lead I and a Q wave in lead III (S1Q3)
Rare

14. Bifascicular Block Two of the three fascicles are blocked.
Most common is RBBB with left anterior fascicular block.

15. Subendocardial
Ischemia
Partial occlusion
Transmural
Infarction (MI)
Complete occlusion

16. A. Normal ECG prior to MI
B. Hyperacute T wave changes - increased T wave amplitude and width; may also see ST elevation
C. Marked ST elevation with hyperacute T wave changes (transmural injury)
D. Pathologic Q waves, less ST elevation, terminal T wave inversion (necrosis) 
E. Pathologic Q waves, T wave inversion (necrosis and fibrosis)
F. Pathologic Q waves, upright T waves (fibrosis)

17. Infarction

18. Anterior Infarctions Abnormal Q waves in chest leads
Anterior MI can show loss of R wave progression in the chest leads

19. Inferior Infarctions
Abnormal Q waves in leads II, III, and aVF

20. Lateral Lateral - V5 and V6
High lateral when ST elevation and Q waves localized to leads I and aVL

21. Posterior MI Tall R waves in V1,V2 R/S ratio > 1 in V1, V2
The tall, anterior R waves are mirror images of a pathological, posterior Q waves.
Absences of right axis deviation (found with RVH)
ST segment depression in V1-V3
Often seen with inferior MI

23. Infarctions or BBB RBBB & LBBB
T wave inversion and ST segment depression in V1 & V2 (RBBB) and V5 & V6 (LBBB) MI
T wave inversion and ST segment depression in additional leads
Likely loss of R wave progression

24. Infarctions and BBB RBBB and MI
usual ECG changes in leads other than V1 and V2
septal MI - upright T waves in V1 and V2
with just RBBB the T waves should be inverted so upright T waves w/ RBBB are “abnormal” and indicated septal MI

25. Infarctions and LBBB
Infarctions often damage the left bundle branch leading to a new or recent LBBB
expect to see upright T waves in left chest leads
septal MI are very difficult to assess with LBBB

26. Subendocardial Ischemia
ST Segment depression
Anterior leads (I, aVl and V1-V6)
Inferior leads (II, III, and aVf)
may see ST segment elevation in aVr
T wave inversion
Poor R wave progression

27. Subendocardial Infarction
No Q waves (non-Q wave infarction)
Persistent ST segment depression
T wave inversion

28. Sinus Bradycardia
HR less than 60 bpm

29. Sinus Tachycardia
HR > 100 bpm

30. Premature Atrial Complexes (PAC)
Normal conduction
Conducted with aberration
a fascicles or bundle branch is refractory
wide QRS
Non-conducted
the AV node was still refractory; P wave will be close to the T wave
no QRS complex

31. Atrial Tachycardia

32. AV Nodal Reentrant Tachycardia
Figure 14-6
Rapid recirculating impluse in the AV node area ( beats/min)
No P waves (hidden in QRS complex) or may be just before or after the QRS complex
Negative P waves in lead II

33. Atrial Flutter Sawtooth; F waves (easiest seen in II, III, & aVF)
Atrial rate of about 300 bpm
Ventricular rate150, 100 or 75 beats/min
2:1, 3:1 and 4:1

34. Atrial Fibrillation No organized depolarization in atria.
Irregular “f waves” can range from looking almost like P waves to a flat line.
Atrial rate is about 600 bpm
Normal QRS w/ ventricular rate ~ but random & irregular

35. Junctional Rhythm

36. Accelerated Junctional Rhythm

37. WPW

38. First Degree AV Block

39. 2nd Degree AV Block, Type 1

40. 2nd Degree AV Block, Type 2

41. 2rd Degree AV Block

42. Premature Ventricular Contractions
Characteristics
Premature and occur before the next normal beat
Wide (> 0.12 ms) and the T wave is usually opposite of the QRS
Bizarre looking
PVCs usually precede a P wave.
A nonsinus P wave may follow the PVC

43. PVC Unifocal (monomorphic) PVCs same appearance in the same lead
small focus
normal and diseased hearts

44. PVC Polymorphic (multifocal and multiform) PVCs
different appearance in the same lead
multiform = different coupling intervals
multifocal = same coupling intervals
usually diseased hearts
Multiform

45. Idioventricular Rhythm

46. Couplet

47. Triplet

48. Bigeminy and Trigeminy

49. Ventricular Tachycardia
...more than three PVCs

50. Torsades de Pointes

51. Ventricular Fibrillation
Note the course and fine waves