1. ECG Interpretation

2. What is an ECG Electrocardiogram
Traces the electrical activity of the heart
12 lead, 15 lead

3. Uses of ECG Tracing Ischemia/infarct Arrhythmias
Ventricular and atrial enlargements
Conduction defects
Pericarditis
Effects of some drugs and electrolytes

4. ECG

5. How to Conduct an ECG Patient lies flat on back
Electrodes are placed on the body
Sites may need to be shaved or cleaned to ensure the leads will stick properly.
Patient will lie as still as possible, hold breath, or put hands under bottom to keep from moving.
The results are then printed out on paper for MD to review.

6. ECG Strip

7. Lead Placements V1 - Junction of the 4th ICS, Right sternal border
V2 - Junction of the 4th ICS, Left sternal border
V3 - Midway between V2 and V4
V4 - Junction of 5th ICS, Mid clavicle
V5 - Anterior aspect of axilla, same line as V4
V6 - Mid axilla, same line a V4
4 limb leads (for grounding etc)

8. Lead Placements Cont’

10. Normal Conduction Pattern

11. Understanding the Waves

12. Each wave P Q R S T

14. ECG Strip r/t heart

15. Understanding the Waves
One small box = 0.04 seconds
One large box = 0.2 seconds
5 large boxes = 1 second

17. Understanding the Waves
Baseline (what is it?)
P wave
Length of time it takes the impulse to pass from the SA node to the AV node
Should precede every QRS wave
PR interval
Should be no longer than 0.12 – 0.2

18. Understanding the Waves
QRS
Should be no longer than 0.12
If energy is going towards a positive electrode (camera), the picture will show a positive QRS complex
If energy is going away from positive electrode, the picture will show a negative QRS complex
If energy is toward the positive electrode and then passes by it, the QRS will be biphasic
Ventricle contracting

19. Understanding the Waves
T wave
Should always start from baseline
Will indicate ischemia

20. Understanding an ECG Is as easy as… 1. 2. 3. = rate = intervals
= rhythm

21. Step 1 = Rate Different ways to calculate a rate:
a) ECG usually tells you
b) Locate a QRS that is close to a big line and count to next big line: 300, 150, 100, 75, 60, 50
c) take a 6 second strip, count QRS and multiply by 10 (hint: the middle of V3 on the lead II strip is 6 seconds)
One small box = 0.04 sec.
One large box = 0.2 sec.
5 large boxes = 1 sec.
300, 150, 100, 75, 60, 50, 45, 37…

22. Step 1 = Rate (cont’)
Checking the regularity:
map out QRS’s

23. Step 2 = Intervals
We assess intervals to see where the impulse is coming from (pacemaker beat)
Remember:
PR interval: normal is
QRS interval: normal is less than or equal to 0.12
One small box = 0.04 sec.
One large box = 0.2 sec.
5 large boxes = 1 sec.

24. Step 3 = Rhythm
The biggest question in relation to rhythm is…

25. Is this rhythm affecting my patient?

26. (Normal) Sinus Rhythm 60-80 bpm P preceding each QRS Normal intervals
What do we want to do for this patient?

27. Normal ECG

28. Other Sinus Rhythms Sinus bradycardia
a sinus rhythm with a rate <60 bpm
What do we want to do for this patient?

29. Other Sinus Rhythms Sinus tachycardia
a sinus rhythm with a rate >80 bpm
What do we want to do for this patient?

30. Atrial Arrhythmias Atrial fibrillation (A-fib) irregular rate
no discernable P waves
increased risk of strokes due to clots that might form due to fibrillation (patients are usually on anticoagulation therapy)
What do we want to do for this patient?

31. Atrial fibrillation

32. Atrial Arrhythmias Cont’
Atrial flutter
saw tooth in appearance
irregular rate

33. Atrial flutter
What do we want to do for this patient?

34. Blocks 1st degree AV block a PR interval that exceeds 0.20 sec
What do we want to do for this patient?

35. Blocks Cont’ 2nd degree AV block (Mobitz) a) type I (Wenckebach)
longer and longer PR intervals until a QRS is dropped
What do we want to do for this patient?

36. Blocks Cont’ b) type II P waves and then suddenly a QRS is dropped
P’s are regular
What do we want to do for this patient?

37. Blocks Cont’ 3rd degree AV block HR <40 bpm
a complete block of electrical activity from atria to ventricle
P’s are regular
What do we want to do for this patient?

38. Ventricular Rhythms Ventricular fibrillation
complete breakdown of all rhythm
a) course
b) fine
What do we want to do for this patient?

39. V-fib
What’s the first thing to do when coming up on a patient with this rhythm?

40. Ventricular Rhythms Cont’
Ventricular tachycardia (V-tach)
impulse originates in the ventricle
always has a wide QRS complex
What do we want to do for this patient?

41. V-tach What’s the first thing to do when coming up on a patient with this rhythm?

42. Asystole
Pulseless
What do we want to do for this patient?

43. Coronary Arteries

44. MI’s

45. MI’s

46. MI’s
How can you tell on an ECG that your patient is having a heart attack?
T waves
Different views of heart will show different injured areas of heart

47. MI’s
T wave shouldering is classic

48. MI’s How else can you tell that your patient has had an MI?
Cardiac Markers
CK will show in 4-6 hours (starts to come back down after 1 day)
Troponin will show in 4-6 hours (may stay elevated for weeks)
Others are: LDH, CK-MB, myoglobin, AST

49. Locating an MI

50. I Lateral (circumflex) aVR V1 Anterior (Lt ant desc) V4 Anterior
II Inferior (Rt coronary)
aVL Lateral
V2 Anterior
V5 Lateral
III Inferior
aVF Inferior
V3 Anterior
V6 Lateral
Your paper should look like this now…

51. ECG Tissue Damage Locations

53. Where is this MI?