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ECG interpretation for beginners - 1

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ECG interpretation for beginners - 1 Paul Williams Cardiology Specialist Registrar Question 3 What is the rate, rhythm and axis? Any other abnormalities? – PowerPoint PPT presentation

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Title: ECG interpretation for beginners - 1


1
ECG interpretation for beginners - 1
  • Paul Williams
  • Cardiology Specialist Registrar

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How to read ECGs?
  • 1) Have a system!
  • 2) See lots pattern recognition

6
Absolute basics
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A system
  • Quality of ECG?
  • Rate
  • Rhythm
  • Axis
  • P wave
  • PR interval
  • QRS duration
  • QRS morphology
  • Abnormal Q waves
  • ST segment
  • T wave
  • QT interval

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The normal ECG
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Check quality of ECG
  • Patient name
  • Date of ECG
  • ? interference
  • 12 leads
  • Rhythm strip (II or V1) at bottom
  • Scale
  • 25mm/s horizontal
  • 10mm/mV vertical
  • Little square0.04s big square0.2s

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A system
  • Quality of ECG?
  • Rate
  • Rhythm
  • Axis
  • P wave
  • PR interval
  • QRS duration
  • QRS morphology
  • Abnormal Q waves
  • ST segment
  • T wave
  • QT interval

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Rate
  • Computer calculated rate usually correct
  • Still need to manually calculate!
  • 300/RR interval in big squares
  • If irregular average 5
  • Rate is either
  • Normal
  • Bradycardia
  • Tachycardia

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Rate
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Rhythm
  • Different to rate!
  • First thing to ask is there a clear P wave
    before each QRS? (lead II)
  • Regular vs irregular (paper trick.)
  • Tachyarrhythmias vs bradyarrhythmias (separate
    talk)
  • Commonest rhythm is SR (ie. normal)
  • Commonest arrhythmia is AF

14
Axis
Coronal/frontal plane Normal axis is about 60
degrees LAD axis lt -30 degrees RAD axis gt 90
degrees
15
Axis trick
Positive in I and II normal
Positive in I Negative in II LAD
Negative in I Positive in II RAD
16
A system
  • Quality of ECG?
  • Rate
  • Rhythm
  • Axis
  • P wave
  • PR interval
  • QRS duration
  • QRS morphology
  • Abnormal Q waves
  • ST segment
  • T wave
  • QT interval

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P wave
  • Are there P waves.?
  • Pointy P pulmonale (RA hypertrophy)
  • Bifid P mitrale (LA hypertrophy)
  • Not very accurate or useful.

18
PR interval
  • Start of P wave to start of QRS
  • Normal 0.12-0.2s
  • Too short can mean WPW syndrome (ie. an
    accessory pathway), or normal!
  • Too long means AV block (heart block) -
    1st/2nd/3rd degree

19
A system
  • Quality of ECG?
  • Rate
  • Rhythm
  • Axis
  • P wave
  • PR interval
  • QRS duration
  • QRS morphology
  • Abnormal Q waves
  • ST segment
  • T wave
  • QT interval

20
QRS complex
  • Should be lt0.12s duration
  • gt0.12s BBB (either LBBB or RBBB)
  • Pathological Q waves can mean a previous MI (?
    territory)
  • gt25 size of subsequent complex
  • Q waves are allowed in V1, aVR and III

21
BBB
Look at V1 and V6
W I LL ia M LBBB
M a RR o W RBBB
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QRS complex
  • Is there LVH?
  • Sum of the Q or S wave in V1 and the biggest R
    wave in V5 or V6 gt35mm
  • (R wave in aVL gt11mm)
  • Not actually very useful.

23
A system
  • Quality of ECG?
  • Rate
  • Rhythm
  • Axis
  • P wave
  • PR interval
  • QRS duration
  • QRS morphology
  • Abnormal Q waves
  • ST segment
  • T wave
  • QT interval

24
ST segment
  • ST depression
  • Downsloping or horizontal abnormal
  • Ischaemia (coronary stenosis)
  • If lateral (V4-V6), consider LVH with strain or
    digoxin (reverse tick sign)
  • ST elevation
  • Infarction (coronary occlusion)
  • Pericarditis (widespread)
  • These are usually in territories eg.
    anterior/lateral/inferior etc. and will be
    present in contiguous leads

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T wave
  • Peaked (hyperkalaemia or normal young man)
  • Inverted/biphasic (ischaemia, previous infarct)
  • Small (hypokalaemia)
  • No pot, no tea!

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QT interval
  • Dont worry about too much
  • Start of QRS to end of T wave
  • Needs to be corrected for HR
  • Various formulae
  • eg. Bazetts
  • Computer calculated often wrong
  • Long QT can be genetic (long QT sy.) or secondary
    eg. drugs (amiodarone, sotalol)
  • Associated with risk of sudden death due to
    Torsades de Pointes

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Question 1
  • What is the rate, rhythm and axis?
  • Any other abnormalities?

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Question 2
  • What is the rate, rhythm and axis?
  • Any other abnormalities?

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Question 3
  • What is the rate, rhythm and axis?
  • Any other abnormalities?

35
Question 4
  • What is the rate, rhythm and axis?
  • Any other abnormalities?
  • How would you manage this patient?

36
Question 5
  • What is the rate, rhythm and axis?
  • What is the main problem with the patient?

37
Take home messages
  • Remember your system!
  • See lots (pattern recognition)

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Further reading
ECG made easy, 7th ed Hampton ECG
Interpretation made Incredibly Easy, 4th ed
Springhouse (? nurses) www.Emedu.org/ecg
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