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How to read ECG
ECG
• Representation of Electrical activity of
heart
ECG Leads
• 12 lead ECG
• 6 limb leads: Lead I, II, III
aVL, aVR, aVF
• 6 Chest Leads: V1, V2,V3, V4, V5, V6
ECG paper
Speed 25mm/s
• 1 large square= 5 small square [5mm]
Voltage
• 10mm =1mV
Appearance of waves
• Positive deflection [upward]
• If electrical impulses flowing towards
that lead
• Negative deflectio...
Origin of waves
P wave Atrial depolarization
PR interval Atrial depolarization to start of
ventricular depolarization
QRS complex Ventricu...
Systematic approach
• The following 14 points
should be analyzed
carefully in every ECG:
• Standardization
• Heart rate
• ...
Standardization
Heart Rate
• 1500/RR
•If HR is irregular
Count no. of QRS complexes in 30 large squares=
6 sec
Multiply it with 10
HR [per min]
Rate calculation
• Memorize the number sequence: 300,
150, 100, 75, 60, 50
• ECG machines: print out HR
• DO NOT RELY ON IT!!!!
• Always Calculate yourself.
• Bradycardia: <60/min
• Tachycardia: >1...
Rhythm
• Rhythm strip: prolonged recording of
Lead II
• Sinus rhythm ?
• Each QRS complex preceded by P wave
• Regular/ ir...
•Regular
Sinus rhythm
Irregular
QRS AXIS
• Indicator of overall direction that wave
of depolarization takes when passing
through ventricles
• Also called ...
• Photo
• Right axis deviation [RAD]
• Beyond +90°
• Left Axis Deviation [LAD]
• Beyond -30°
Method 1
• Most precise method
• Use of vectors
• Measure overall height of QRS in lead I
& aVF
• Plot in graph paper
• Me...
Method 2
• Quick method
• Identify limb lead in which QRS complex
is isoelectric
• [with equal positive & negative
deflect...
Method 3
• For quick assessment
• Look at QRS complexes in lead I & II
• Predominantly
positive QRS in
lead I
• Axis between
-90 to +90
• Excludes RAD
• Predominantly
positive QRS in
lead II 
• Axis between
-30 to +150
• Excludes LAD
Lead I Lead II Cardiac Axis
QRS Positive QRS Positive Normal Axis
QRS Positive QRS Negative Left Axis
Deviation
QRS Negati...
• LAD
• WPW syndrome
• LBBB
• Inferior wall MI
• RAD
• RVH
• WPW syndrome
• Anterolateral MI
• Dextrocardia
P wave
• Present or not?
• Sinus rhythm
• If completely absent
•Atrial Fibrillation
•Hyperkalemia
• If intermittently abse...
• Inverted P waves?
• Incorrect positioned electrodes
• Dextrocardia
• Abnormal atrial depolarization
• Height of P waves
• > 2.5 mm: tall
• Indicative of Right Atrial enlargement
• P Pulmonale
P PULMONALE
P MITRALE
• Width of P waves
• >2mm width: abnormal
• Bifid P wave
• Indicates Left Atrial enlargement
• P Mitrale
PR Interval
• From start of P wave to start of R wave
• Normally
• Not <3 small squares
• Not > 5 small squares
• Consiste...
Short PR Interval
• AV junctional rhythm
• WPW syndrome
• Lown –Ganong-Levine syndrome
Long PR Interval
• Denotes delay in conduction through AV
node
• First Degree Block
• PR prolonged, constant
Second degree Block
• Mobitz Type I
• PR progressively increase until one P
wave fails to produce QRS complex
• Mobitz Type II
• PR interval normal & fixed,
• But occasional P waves fail to produce
QRS
• Third Degree Block [Complete AV Block]
• No relationship between P waves & QRS
complex
• 2:1 Block
• Alternate P waves are not followed by
QRS complex
Q WAVE
• First negative deflection in QRS complex
• ? Pathological Q waves
• If
• >2 small squares deep
• >1 small square ...
QRS complex
• Appearance of QRS Complex vary from
lead to lead
• Width: Narrow/ wide
• Wide QRS:
• > 3 small squares
• Bundle branch block
• Ventricular arrhythmia
• Size of QRS complex
• Small:
• Pericardial effusion
• ?incorrect calibration
• Big QRS complex
• Ventricular hypertrophy: R/L
• WPW syndrome
Progression of R wave
• V1: small R wave , large S wave,
• Gradually R wave increases, S wave
decreases
• V6: small Q wave...
Progression of R wave
Left ventricular Hypertrophy
• R Wave in V5 or V6 >25mm
• S Wave in V1 or V2 > 25mm
• Sum of R wave in V5 Or V6 & S wave i...
LVH
Right Ventricular Hypertrophy
• Right axis deviation
• Deep S Waves in leads V5 & V6
• R>S in V1
• RBBB
RBBB
• Right Bundle Branch Block
• Broad QRS complex
• Small r wave in V1, small Q wave in V6
• S wave in V1, R wave in V6...
LBBB
• Left Bundle Branch Block
• Broad QRS
• Small Q wave in V1, Small r wave in V6
• R wave in V1, S wave in V6
• S wave...
• “WILLIAM MORROW”
• William: „W‟ in V1 & „M‟ in V6: LBBB
• Morrow: „M‟ in V1 & „W‟ in V6: RBBB
• LBBB
• Ischemic Heart
Disease
• Cardiomyopathy
• LVH
• Fibrosis
• RBBB
• Ischemic heart
disease
• Cardiomyopathy
• ASD
•...
ST Segment
• From end of S wave to start of T Wave
• Normally: Isoelectric
• ? Depressed/ elevated
• Elevated ST segment
• Acute MI
• Prinzmetal’s angina
• Pericarditis
• LV aneurysm
• High take off
• Depressed ST segment
• Myocardial ischemia
• Posterior MI
• Ventricular hypertrophy with ‘Strain’
• Drugs: Digoxin
Ventricular Hypertrophy with
“strain” pattern
• Tall R waves
• Deep S waves
• ST segment depression
• T wave inversion
T Wave
T wave
• Inverted?
• Normal in aVR
• V1,V2, III
• Size
• Normal: not > ½ size of preceeding
QRS complex
• Too small?
• Too...
Tall T waves
• Hyperkalemia
• Acute MI
Too small T Waves
• Hypokalemia
• Pericardial effusion
• hypothyroidism
Inverted T waves
• Normal in few leads: aVR, V1, V2, III
• MI
• Myocardial ischemia
• Ventricular hypertrophy with “strain...
QT Interval
• From start of QRS complex to end of T
wave
• Varies with HR
Corrected QT interval
• QTC
• QTC =QT/√RR
• Normal: 0.35-0.43 sec
Prolonged QTc
• If ≥0.44 sec
• Hypocalcemia
• Acute myocarditis
• Torsades de pointes
U waves
• Mostly in anterior chest leads
• Difficult to identify clearly
• Prominent U Waves
• Hypoklemia
• Hypercalcemia
• Hyperthyroidism
Common ECG Problems
ACUTE MI
Ischemia
HYPERKALEMIA
LVH WITH STRAIN
PERICARDITIS
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
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How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
How to read ECG
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How to read ECG
How to read ECG
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How to read ECG

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Transcript of "How to read ECG"

  1. 1. How to read ECG
  2. 2. ECG • Representation of Electrical activity of heart
  3. 3. ECG Leads • 12 lead ECG • 6 limb leads: Lead I, II, III aVL, aVR, aVF • 6 Chest Leads: V1, V2,V3, V4, V5, V6
  4. 4. ECG paper Speed 25mm/s • 1 large square= 5 small square [5mm] Voltage • 10mm =1mV
  5. 5. Appearance of waves • Positive deflection [upward] • If electrical impulses flowing towards that lead • Negative deflection [downward] • If electrical impulses flowing away from that lead
  6. 6. Origin of waves
  7. 7. P wave Atrial depolarization PR interval Atrial depolarization to start of ventricular depolarization QRS complex Ventricular depolarization T wave Ventricular repolarization QT interval Ventricular depolarization & repolarization U wave ? Interventricular septal repolarization
  8. 8. Systematic approach • The following 14 points should be analyzed carefully in every ECG: • Standardization • Heart rate • Rhythm • P waves • PR interval • QRS voltages • QRS interval • QT interval • Mean QRS axis • Precordial R-wave progression • Abnormal Q waves • ST segments • T waves • U waves
  9. 9. Standardization
  10. 10. Heart Rate • 1500/RR
  11. 11. •If HR is irregular Count no. of QRS complexes in 30 large squares= 6 sec Multiply it with 10 HR [per min]
  12. 12. Rate calculation • Memorize the number sequence: 300, 150, 100, 75, 60, 50
  13. 13. • ECG machines: print out HR • DO NOT RELY ON IT!!!! • Always Calculate yourself. • Bradycardia: <60/min • Tachycardia: >100/min
  14. 14. Rhythm • Rhythm strip: prolonged recording of Lead II • Sinus rhythm ? • Each QRS complex preceded by P wave • Regular/ irregular?
  15. 15. •Regular Sinus rhythm
  16. 16. Irregular
  17. 17. QRS AXIS • Indicator of overall direction that wave of depolarization takes when passing through ventricles • Also called ANGLE • Measured • in degrees
  18. 18. • Photo
  19. 19. • Right axis deviation [RAD] • Beyond +90° • Left Axis Deviation [LAD] • Beyond -30°
  20. 20. Method 1 • Most precise method • Use of vectors • Measure overall height of QRS in lead I & aVF • Plot in graph paper • Measure the ANGLE of vector
  21. 21. Method 2 • Quick method • Identify limb lead in which QRS complex is isoelectric • [with equal positive & negative deflection] • Implies: electric flow is at Right angle to this lead
  22. 22. Method 3 • For quick assessment • Look at QRS complexes in lead I & II
  23. 23. • Predominantly positive QRS in lead I • Axis between -90 to +90 • Excludes RAD
  24. 24. • Predominantly positive QRS in lead II  • Axis between -30 to +150 • Excludes LAD
  25. 25. Lead I Lead II Cardiac Axis QRS Positive QRS Positive Normal Axis QRS Positive QRS Negative Left Axis Deviation QRS Negative QRS Positive Right Axis Deviation
  26. 26. • LAD • WPW syndrome • LBBB • Inferior wall MI • RAD • RVH • WPW syndrome • Anterolateral MI • Dextrocardia
  27. 27. P wave • Present or not? • Sinus rhythm • If completely absent •Atrial Fibrillation •Hyperkalemia • If intermittently absent •Sinus arrest
  28. 28. • Inverted P waves? • Incorrect positioned electrodes • Dextrocardia • Abnormal atrial depolarization
  29. 29. • Height of P waves • > 2.5 mm: tall • Indicative of Right Atrial enlargement • P Pulmonale
  30. 30. P PULMONALE P MITRALE
  31. 31. • Width of P waves • >2mm width: abnormal • Bifid P wave • Indicates Left Atrial enlargement • P Mitrale
  32. 32. PR Interval • From start of P wave to start of R wave • Normally • Not <3 small squares • Not > 5 small squares • Consistent
  33. 33. Short PR Interval • AV junctional rhythm • WPW syndrome • Lown –Ganong-Levine syndrome
  34. 34. Long PR Interval • Denotes delay in conduction through AV node • First Degree Block • PR prolonged, constant
  35. 35. Second degree Block • Mobitz Type I • PR progressively increase until one P wave fails to produce QRS complex
  36. 36. • Mobitz Type II • PR interval normal & fixed, • But occasional P waves fail to produce QRS
  37. 37. • Third Degree Block [Complete AV Block] • No relationship between P waves & QRS complex
  38. 38. • 2:1 Block • Alternate P waves are not followed by QRS complex
  39. 39. Q WAVE • First negative deflection in QRS complex • ? Pathological Q waves • If • >2 small squares deep • >1 small square wide • >25% of height of the following R wave in depth
  40. 40. QRS complex • Appearance of QRS Complex vary from lead to lead
  41. 41. • Width: Narrow/ wide • Wide QRS: • > 3 small squares • Bundle branch block • Ventricular arrhythmia
  42. 42. • Size of QRS complex • Small: • Pericardial effusion • ?incorrect calibration
  43. 43. • Big QRS complex • Ventricular hypertrophy: R/L • WPW syndrome
  44. 44. Progression of R wave • V1: small R wave , large S wave, • Gradually R wave increases, S wave decreases • V6: small Q wave, large R wave • V3 and V4 : located midway between V1 and V6, QRS complex nearly isoelectric in one of these leads
  45. 45. Progression of R wave
  46. 46. Left ventricular Hypertrophy • R Wave in V5 or V6 >25mm • S Wave in V1 or V2 > 25mm • Sum of R wave in V5 Or V6 & S wave in V1 or V2 >35mm
  47. 47. LVH
  48. 48. Right Ventricular Hypertrophy • Right axis deviation • Deep S Waves in leads V5 & V6 • R>S in V1 • RBBB
  49. 49. RBBB • Right Bundle Branch Block • Broad QRS complex • Small r wave in V1, small Q wave in V6 • S wave in V1, R wave in V6 • R‟ wave in V1, S wave in V6
  50. 50. LBBB • Left Bundle Branch Block • Broad QRS • Small Q wave in V1, Small r wave in V6 • R wave in V1, S wave in V6 • S wave in V1, R‟ wave in V6
  51. 51. • “WILLIAM MORROW” • William: „W‟ in V1 & „M‟ in V6: LBBB • Morrow: „M‟ in V1 & „W‟ in V6: RBBB
  52. 52. • LBBB • Ischemic Heart Disease • Cardiomyopathy • LVH • Fibrosis • RBBB • Ischemic heart disease • Cardiomyopathy • ASD • Massive pulmonary embolism
  53. 53. ST Segment • From end of S wave to start of T Wave • Normally: Isoelectric • ? Depressed/ elevated
  54. 54. • Elevated ST segment • Acute MI • Prinzmetal’s angina • Pericarditis • LV aneurysm • High take off
  55. 55. • Depressed ST segment • Myocardial ischemia • Posterior MI • Ventricular hypertrophy with ‘Strain’ • Drugs: Digoxin
  56. 56. Ventricular Hypertrophy with “strain” pattern • Tall R waves • Deep S waves • ST segment depression • T wave inversion
  57. 57. T Wave
  58. 58. T wave • Inverted? • Normal in aVR • V1,V2, III • Size • Normal: not > ½ size of preceeding QRS complex • Too small? • Too large?
  59. 59. Tall T waves • Hyperkalemia • Acute MI
  60. 60. Too small T Waves • Hypokalemia • Pericardial effusion • hypothyroidism
  61. 61. Inverted T waves • Normal in few leads: aVR, V1, V2, III • MI • Myocardial ischemia • Ventricular hypertrophy with “strain” • Digoxin toxicity
  62. 62. QT Interval • From start of QRS complex to end of T wave • Varies with HR
  63. 63. Corrected QT interval • QTC • QTC =QT/√RR • Normal: 0.35-0.43 sec
  64. 64. Prolonged QTc • If ≥0.44 sec • Hypocalcemia • Acute myocarditis • Torsades de pointes
  65. 65. U waves • Mostly in anterior chest leads • Difficult to identify clearly
  66. 66. • Prominent U Waves • Hypoklemia • Hypercalcemia • Hyperthyroidism
  67. 67. Common ECG Problems
  68. 68. ACUTE MI
  69. 69. Ischemia
  70. 70. HYPERKALEMIA
  71. 71. LVH WITH STRAIN
  72. 72. PERICARDITIS
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