2. ECG Interpretation Overview
1. ECG type &recording
2. Rate, Rhythm, Axis
3. P wave
4. PR interval + segment
5. Q Waves, R waves
6. QRS complex
7. ST segment
8. T wave
9. U wave
10. QT interval
3. ECG Interpretation Overview
11. Additional waves (D O E)
12. Chamber hypertrophy
13. Other
- T oxicology
- I schaemia
- E lectrolytes
- sudden death ECG
Q B R A D W H
- dextrocardia
- lead reversals
- artefacts
- pacing spikes
4. Putting it all together…
Diagnosis
Differential diagnoses
Life threats
12. Rate, Rhythm, Axis
RATE
Normal 60-100/min (tachy/bradycardia)
Method: 300/RR(large squares)
OR 1500/RR(small squares)
OR number of QRS x 6 (if 25mm/s)
RHYTHM
Pattern: regular or irregular (reg irreg or irreg irreg)
7 STEP APPROACH
22. PR Interval
Duration (N= 120-200ms)
Short (<120ms)
1. Preexcitation Syndrome
eg WPW, Lown - Ganong- Levine (LGL)
2. AV (nodal) junctional Rhythm
Long (>200ms)
1. 1 HB (alone or with other blocks)
Varying (blocks)
23. Short PR Interval - WPW
Short PR interval (<120ms)
Prolonged QRS (>110ms) + early slurred upstroke (delta wave)
Dominant R in V1-3
ST seg & T wave discordant changes
31. R waves
NORMAL
Transition point V3-V4
ABNORMAL
Dominant R wave in aVR
Dominant R wave in V1
Poor R wave progression (Ht ≤ 3 mm in V3)
32. Dominant R Wave in aVR
CAUSES
1. Poisoning with Na channel blocking medications
(Criteria: R wave height > 3 mm, R/S ratio > 0.7)
2. Dextrocardia
3. Incorrect lead placement (L & R arms reversed)
33. Dominant R Wave in V1
CAUSES
1. RVH (PE, L to R shunt)
2. RBBB
3. POSTERIOR MI (+ STE in leads V7,8,9)
4. WPW TYPE A
5. Hypertrophic Cardiomyopathy
6. Dextrocardia
7. Normal in children and young adults
34.
35. Poor R Wave Progression
CAUSES
1. Prior anteroseptal infarction
2. LVH
3. Dilated cardiomyopathy
4. Transpositioin of leads V1 & V3
5. May be normal
36.
37. ECG Interpretation Template
1. ECG type &recording
2. Rate, Rhythm, Axis
3. P wave
4. PR interval + segment
5. Q Waves, R waves
6. QRS complex
38. QRS Complex
Duration
N = 70-100ms
narrow (Supraventricular)
wide (ventricular or SVT
with aberrant
conduction)
Amplitude
High voltage eg LVH
Low voltage
Alternans eg
pericardial effusion
Morphology
Notched
RBBB
LBBB
Spot Diagnoses
Brugada Syndrome
WPW Syndrome (delta
waves)
Tricyclic poisoning (wide
QRS + dom R in aVR
39.
40. ECG Interpretation Template
1. ECG type &recording
2. Rate, Rhythm, Axis
3. P wave
4. PR interval + segment
5. Q Waves, R waves
6. QRS complex
7. ST segment
48. ECG Interpretation Template
1. ECG type &recording
2. Rate, Rhythm, Axis
3. P wave
4. PR interval + segment
5. Q Waves, R waves
6. QRS complex
7. ST segment
8. T wave
9. U wave
49. U Wave
Normal
= 0.5 mm (max 2mm)
= 10% TW (max 25% TW)
Prominent
Inverted
50. U Wave
Prominent
> 1-2mm or > 25% ht TW
CAUSES
Bradycardia
HypoK
HypoCa, HypoMg
Hypothermia
Increased ICP
LVH
Hypertrophic cardiomypy
Digoxin
Inverted
abnormal if in leads with upright
T waves
CAUSES
Heart disease
**HIGHLY SPECIFIC FOR HEART
DISEASE**
**Predicts >75% stenosis of
LAD/LMCA and suggests LV
dysfn**
51. ECG Interpretation Template
1. ECG type &recording
2. Rate, Rhythm, Axis
3. P wave
4. PR interval + segment
5. Q Waves, R waves
6. QRS complex
7. ST segment
8. T wave
9. U wave
10. QT interval
52. QT Interval
Normal QTc
= 390-440ms M/460 ms
F
< ½ preceding RR
inversely prop to HR
Measure in lead II or V5-6
Large U waves (>1 mm) fused
to T included in measurement
Small, separate U waves
excluded in measurement
Long (>440/460 ms)
Short (<350ms)
55. Additional Waves (D O E)
Delta Wave
WPW
= slurred upstroke to QRS
Additional Features:
Short PR interval (<120ms)
Broad QRS (>100ms)
56. Additional Waves (D O E)
Osborn Wave (J waves)
= positive deflection at J point
Most prominent in precordial leads
Causes
Hypothermia
Hyper Ca
Medications
Raised ICP
Normal varient
57. Additional Waves (D O E)
Epsilon Wave
Arrythmogenic RV dysplasia (in
30% patients)
= pos deflection buried in end of
QRS
Additional Features
TWI V1-3
Prolonged S Wave upstroke V1-3
58.
59. ECG Interpretation Template
11. Additional waves (D O E)
12. Chamber hypertrophy
13. Other
- T oxicology
- I schaemia
- E lectrolytes
- sudden death ECG
- dextrocardia
- lead reversals
- artefacts
- pacing spikes
62. References
What-When-How In Depth Tutorials and Information:
http://what-when-how.com/paramedic-care/diagnostic-
ecgthe-12-lead-clinical-essentials-paramedic-care-
part-5/
ECG Basics-Parts of the ECG:
http://www.emergsource.com/?page_id=90
Academic Life in Emergency Medicine:
http://www.aliem.com/posterior-myocardial-infarction-
how-accurate-is-the-flipped-ecg-trick/