1. ECG
ELECTROCARDIOGRAM
V.S.RASHMI PRIYEM
ULTRA’S BEST Dental Science College,Madurai

2. HISTORY
 In 1895 -William Einthoven , invented the
ECG

3. Modern ECG

4. What is an ECG?
 The Electrocardiogram (ECG) is a Graphic
Representation of the Electrical Events of the
Cardiac Cycle
 Each Event has a DistinctiveWaveform

5. ECG
 Electrocardiography is the Method of
Recording of ECG
 Electrocardiograph is the Machine that
Records ECG, which Amplifies theVoltages
and gives a Plot ofVoltage as a Function of
Time

6. Concept behind ECG
 Body is aVolume Conductor, i.e. Body Fluids
are a Good Conductor Of Electricity
 Therefore, Electrical Changes occurring in the
Heart with Each Beat are Conducted all over
the Body and can be Picked Up from the Body
Surface
 The Record of these Electrical Fluctuations
during the Cardiac Cycle is called
Electrocardiogram.

7. ECG is Useful for Assessing:
 1. Anatomical Orientation of the Heart.
 2. Relative Size of the Chambers.
 3. Disturbances of Rhythm and Conduction.
 4. Ischemia of the Myocardium, if Present.
 5. Location, Extent and Progress of Myocardial
Infarction.
 6. Effects of Altered Electrolyte Concentration.
 7. Influence of Certain Drugs like Digitalis.
 8. Efficiency of Electronic Pacemaker Function.

8. With ECGs we can Identify
 Arrhythmias
 Myocardial Ischemia and Infarction
 Pericarditis
 Chamber Hypertrophy
 Electrolyte Disturbances (i.e. Hyperkalemia,
Hypokalemia)
 DrugToxicity (i.e. Digoxin and Drugs which
Prolong the QT Interval)

9. The Advancement
 In Modern Electrocardiography,TwoTypes of
ECG machines are used:
 (1) the String Galvanometer
 (2) the Radioamplifier

10. ECG paper
 ECG paper is a Strip of Graph Paper that containsVertical
and Horizontal Lines 1 mm apart.
 The Horizontal Axis representsTime whereas theVertical
Axis denotes Amplitude.
 There are Small Squares of 1 mm x 1 mm, and Big Squares
of 5 mm x 5 mm.
 After every 5 Big Squares, the HeavyVertical Line
overshoots the margin.
 The ECG paper is a Heat-Sensitive Plastic-Coated Paper.
 The ECG is inscribed on this paper by a Hot Stylus.
 Conventional ECG is taken at a Speed of 25 mm/s.
 One Small Square (1 mm) corresponds to 0.04 second,
while the Big Square (5 mm) is Equivalent to 0.20 second.

11. ECG Paper

12. Einthoven Triangle
 Einthoven's triangle is an Imaginary
Formation of Three Limb Leads in a Triangle
used in Electrocardiography, formed by the
Two Shoulders and the Pubis.
 The shape forms an Inverted Equilateral
Triangle with the Heart at the Center that
produces Zero Potential when theVoltages
are Summed.

13. ECG Leads
 An ECG Lead is a pair of Electrodes used to
detect the Potential Differences of the Heart.
 Two Categories -The Direct, and the Indirect
Leads.
 1.When a Lead is Directly Applied to the Surface
of the Heart, it is called Direct Lead - Used to
Record Cardiac Activities during Cardiac Surgery.
 2.When the Leads are Applied Away from the
Heart (Usually on the Body Surface) to Record
the Cardiac Activities, they are called Indirect
Leads.

14.  Conventionally, ECG is recorded using
Indirect Leads.
 Indirect Leads are Limb Leads, Chest Leads,
and Esophageal Leads.
 Usually, aTwelve-Lead Recording is
performed for Complete Analysis of the ECG -
Six Limb Leads and Six Chest Leads.

15. Limb Leads
 Limb Leads lie in the Frontal Plane.
 TwoTypes: Bipolar and Unipolar Limb Leads.
 1. A Bipolar Lead Records the Potential
Difference BetweenTwo Electrodes placed at
different sites.
 2. A Unipolar Lead is a pair of Electrode giving
the Potential Difference Between An Exploring
And An Indifferent Electrode
 3.The Reference Input comes from a
Combination Of Electrodes at different sites that
roughly gives a Zero Potential.

16. Bipolar Limb Leads
 Three Bipolar Standard Limb Leads (Leads I,
II, and III) are the Original Leads Selected By
Einthoven to Record Electrical Potential on
the Frontal Plane.
 The Electrodes are attached to the Right
Arm, Left Arm, and Left Foot.
 Another Electrode is applied to the Right Leg,
which Acts As A GroundWire to Prevent
External Disturbances during Recording.

17. Bipolar Limb Leads
 Lead I : Between the Right Arm (Negative
Electrode) and the Left Arm (Positive
Electrode).
 Lead II : Between the Right Arm (Negative
Electrode) and the Left Leg (Positive
Electrode).
 Lead III: Between the Left Arm (Negative
Electrode) and the Left Leg (Positive
Electrode).

18. Bipolar Limb Leads

19. Unipolar Limb Leads
 In the method of recording by Unipolar Leads, one
Electrode is the Active or Recording Electrode and
the other one is the Indifferent Electrode
 Three Unipolar Limb Leads: aVR, aVL, and aVF
 ‘a’ stands for Augmentation of the Leads
 ‘V’ stands for Unipolar
 R, L, and F indicate that the Exploring or Active
Electrode is on the Right Arm, LeftArm, and Left
Foot respectively
 The Indifferent Electrode is connected to the
remainingTwo Leads through a Resistance Coil

20. Positioning of Unipolar Limb
Leads
 aVR: Between the Right Arm (Positive
Electrode) and Left Arm + Left Leg (Negative
Electrode).
 aVL: Between the Left Arm (Positive
Electrode) and Right Arm + Left Leg
(Negative Electrode).
 aVF: Between the Left foot (Positive
Electrode) and Right Arm + Left Arm
(Negative Electrode).

21. Unipolar Limb Leads

22. Chest Leads
 Chest Leads or Precordial Leads lie in the
Transverse Plane.
 TwoTypes: Unipolar and Bipolar Chest Leads.

23. Unipolar Chest Leads
 There are Six Precordial Leads that are used
routinely
 These areV1 toV6
 ‘V’ stands for Unipolar
 These Leads employ an Exploring Electrode on the
Chest Surface.
 The reference or the Indifferent Electrode is
connected to the Right Arm, LeftArm and Left Leg
through the High Resistance, which is calledWilson’s
Terminal that is Maintained at Zero Potential.
 The Right Leg is connected with a Grounding
Electrode to Avoid Electrical Interference

24. Unipolar Chest Leads
 V1 : In the Right Fourth Intercostal Space at the
Right Border of the Sternum.
 V2 : In the Left Fourth Intercostal Space at the
Left Border of the Sternum.
 V3 : At the Midpoint BetweenV2 andV4.
 V4 : In the Left Fifth Intercostal Space on the
Midclavicular Line.
 V5 : In the Left Fifth Intercostal Space on the
Anterior Axillary Line.
 V6 : In the Left Fifth Intercostal Space on the
Midaxillary Line.

25. Unipolar Chest Leads

26. Bipolar Chest Leads
 Used Before the Discovery of Unipolar Chest
Leads.
 Lewis Lead is a Special Bipolar Chest Lead
used for Recording ECG in Atrial Arrhythmias.
 This Lead Amplifies theWaves of Atrial
Activity.

27. Esophageal Leads
 In these Leads, an Electrode is fixed on the tip
of the Esophageal Catheter, which is
Positioned in the Esophagus close to the
Heart Chambers.
 Here E stands for ‘Esophageal’ and the
Number indicates the Distance of the
Electrode from the IncisorTeeth expressed in
centimeter.

28. Esophageal Leads
 E15–25 : Used for Recording the Activity of
the Right Atrium.
 E25–35 : Used for Recording the Activity
from the AV Groove Region.
 E40–50 : Used for Recording the Activity
from the Posterior Surface of the Left
Ventricle.

29. NORMAL ECG

30. Waves are Positive or Negative deflections from Baseline.
There are FourWaveforms : PWave, QRS Complex,T and U
Waves.
ECG Waves

31. P Wave

32. P Wave
 PWave is the First Positive Deflection in the
ECG, produced by Atrial Depolarization.

33. P Wave - Waveform
 TheVoltage Change due to Atrial
Depolarization appears on the ECG as the P
Wave, which is Positive with Less Height and
Dome Shape.
 The Height of P wave is Less Because of Less
Atrial Muscle Mass and Dome Shape is due to
the Slow Nature of Depolarization of Atrial
Muscle.
 When Atria are Completely Depolarized, the
ECG tracing Returns to Zero.

34. P Wave - Abnormalities
 PWave may be Abnormal due to Atrial
Enlargement and Intra-Atrial Conduction
Abnormalities.
 Atrial Enlargement results inTall and Peaked
PWaves.

35. QRS Complex

36. QRS Complex
 This consists of Q, R, and SWaves.
 The QRS complex consists of Deflections
produced byVentricular Depolarization

37. QRS Complex - Waveform
 The Q, R, and SWavesTogether form the
QRS Complex, which RepresentsVentricular
Depolarization.
 The Duration, Magnitude and Sharpness of
the QRS Complex Indicate the Greater Muscle
Mass of theVentricles Depolarized and the
Rapidness ofVentricular Excitation.

38. QRS Complex - Abnormalities
 Low Amplitude:
 1. Marked Emphysema
 2. Myxedema
 3. Pericardial Effusion
 4. Cardiomyopathy
 High Amplitude: Seen inVentricular
Hypertrophy

39. Q Wave - Waveform
 TheWave of Depolarization Passes Along the
Bundle Branches, and Purkinje Fibers to First
Excite the Interventricular Septum, which
Depolarizes from Left to Right.
 The Net Dipole of Initial Depolarization is a
Small Downward SharpWave.
 The Small Wave is due to Less Quantity of
Septal Muscle and Less time of
Depolarization and Sharpness is Due to the
Rapidity of Depolarization.

40. Q Waves - Abnormalities
 When the Depth of QWave is more than 25%
of the Height or more than 0.04 s in Duration
is considered Pathological.
 1. Acute or Old Myocardial Infarction
 2. Unstable Angina
 3. Dilated Cardiomyopathy
 4. Hypertrophic Cardiomyopathy

41. R Wave - Waveform
 TheWave of Depolarization then Spreads
from the Subendocardial Muscle Layer to the
Subepicardial Muscle Layer.
 The Deflection in the ECG appears as RWave,
which is an Upward, Bigger and SharpWave.
 R is LargestWave in ECG because of the
Greater Muscle Mass ofVentricles.
 The Sharpness of theWave Represents the
Rapidity of Depolarization.

42. S Wave - Waveform
 The Last Parts to be Depolarized are the
Posterobasal Portion of the LeftVentricle and
the Pulmonary Conus.
 Appears in ECG as a Small Downward Wave.
 The SWave is a Small, Negative and Sharp
Wave.

43. T Wave

44. T Wave - Waveform
 TWave is the Positive Deflection Produced by
Ventricular Repolarization.

45. T Wave - Abnormalities
 TallT wave:
 1. Hyperkalemia
 2. Acute Myocardial Infarction
 InvertedT wave:
 A. Physiological
 1.Young Children
 2. Deep Inspiration (Sometimes)
 3. After Heavy meal (Sometimes)
 B. Pathological
 1.Ventricular Hypertrophy (Strain)
 2. Bundle Branch Block
 3. Digitalis Effect
 4. Myocardial Ischemia

46. U Wave

47. U Wave
 UWave is the Final Positive Deflection in the
ECG.
 Normally, UWave is Not Always Present.
 It Occurs Due to Slow Repolarization of
Papillary Muscle.

48. Segments are Isoelectric lines in ECGTracing.There
areTwo Segments: PR Segment and ST Segment.
ECG Segments

49. PR Segment
 This Lies Between the End of the PWave and
the Beginning of the QRS Complex.

50. ST Segment
 This Lies Between the End of the QRS
Complex and the Beginning of theTWave.
 The Point where the QRS Complex Ends and
the ST Segment Begins is the J Point.
 Elevation of J Point Suggests Myocardial
Ischemia or Infarction.

51. ST Segment - Abnormalities
 ST Elevation: Commonly seen in Acute
Myocardial Infarction and Sometimes in
Acute Pericarditis.
 ST Depression: Commonly seen in Myocardial
Ischemia

52. Intervals Usually includeWaves and Segments.
ECG Intervals

53. PR Interval
 This is the Interval Between the Beginning of
the PWave and the Beginning of the QRS
Complex.
 The Range of PR Interval is from 0.12 to 0.20
second (Average 0.18 s).
 Represents Atrial Depolarization and
Conduction through AV Node.

54. PR Interval - Waveform
 Represents Atrial Depolarization (P wave) and
Atrioventricular Conduction.
 The PR segment is an Isoelectric Line.
 During PR Segment, theWave of
Depolarization passes Slowly through the AV
Node, and then through the His Bundle.
 The Net Dipole isToo Small in Magnitude to
Produce any Deflection on the ECG
Recording.

55. PR Interval - Abnormalities
 Short PR Interval:
 1.WPW Syndrome
 2. Nodal Rhythm
 3. Atrial Premature Beats
 Long PR Interval: (First-DegreeAV block)
 1. Rheumatic Carditis
 2. Digitalis Effect
 3. Coronary Artery Disease

56. QRS Interval
 This is the Interval of the QRS Complex. It is
Measured from the Beginning of the QWave
(or RWave if QWave is Absent) to the J Point.
 The Normal Range is from 0.08 to 0.10
second.
 RepresentsVentricular Depolarization.The
Atrial Repolarization also Occurs inThis
Period.

57. QT Interval
 This is the Interval for QRS Complex, ST
Segment andTWave. It is Measured from the
Beginning of the QRS Complex to the End of
theTWave.
 The Normal Range is Between 0.40 and 0.43
second.
 RepresentsVentricular Depolarization and
Ventricular Repolarization. It Corresponds to
the Duration of Electrical Systole.

58. QT Interval - Abnormalities
 Prolonged QT interval:
 1. Hereditary
 2. Antiarrhythmic Drugs, e.g. Quinidine
 3. Hypokalemia
 4. Acute Myocardial Infarction
 Shortened QT interval:This is of Less Clinical
Significance and May be Seen in
Hypercalcemia.

59. ST Interval
 This is the Interval Between the J Point and
the End ofTWave. It is Calculated by
Deducting QRS Interval from QT interval.
 The Average Duration is 0.32 second.
 RepresentsVentricular Repolarization.

60. PP Interval
 This is the Interval Measured Between Either
the Peak or the Beginning ofTwo Successive
PWaves.
 PP Interval is Measured for Calculation of the
Atrial Rate.

61. RR Interval
 This is the Interval BetweenTwo Successive R
Waves.
 It is Measured Between the Peaks ofTwo
Successive RWaves.
 RR Interval is Measured for Calculating the
Heart Rate (Ventricular Rate).

62. Heart Rate

63. Heart Rate
 The Comment should be Made on Both Atrial
andVentricular Rates.
 The Heart Rate means theVentricular Rate.
 At a Paper Speed of 25 mm/s,
 Atrial Rate per minute is Calculated by dividing 1500
with PP interval (in mm).
 Ventricular Rate per minute is Calculated by dividing
1500 with RR interval (in mm).
 Normally, the RR Interval is equal to the PP
Interval.
 The Normal Heart Rate is 60 to 100 per minute

64. Abnormalities of Heart Rate

65. Bradycardia
 Heart Rate < 60/min
 Sinus Bradycardia
 Junctional (Nodal) Rhythm
 Complete Heart Block

66. Tachycardia
 Heart Rate > 100/min
 SinusTachycardia
 EctopicTachycardia
 Atrial Premature Beats
 Paroxysmal SupraventricularTachycardia
 Atrial Fibrillation
 Atrial Flutter
 Ventricular Premature Beats
 VentricularTachycardia

67. Cardiac Rhythm
 Normally the Rhythm is Regular
 Heart Normally Beats at Regular Intervals.
 Abnormalities of Cardiac Rhythm are called
Arrhythmia

68. The Common Disorders of SA node are Sinus
Arrhythmia, Sick Sinus Syndrome, SinusTachycardia
and Sinus Bradycardia
Disorders of SA Node

69. Sinus Arrhythmia
 A Sinus Arrhythmia is an Irregular Heartbeat
that's EitherToo Fast orToo Slow.

70. Sick Sinus Syndrome
 A Group of Heart Rhythm Problems due to
Problems with the Sinus Node

71. Sinus Tachycardia
 SinusTachycardia, which is a Faster Heart
Rate, Beating Breater than 100 Beats per
Minute

72. Sinus Bradycardia
 Sinus Bradycardia, which is when the Heart
Rate Beats Slower or Lesser than 60 Beats per
Minute

73. The Common Atrial Arrhythmias are Atrial
Premature Beats, Paroxysmal Supraventricular
Tachycardia,Atrial Flutter and Atrial Fibrillation
Atrial Arrhythmias

74. Atrial Premature Beat
 An Extra Heartbeat caused by Electrical
Activation of the Atria (Upper Chambers of
the Heart) from an Abnormal Site before a
Normal Heartbeat would occur

75. Paroxysmal Supraventricular
Tachycardia
 Due to an Abnormality in the Electrical
System of the Heart
 People with this Condition have Sudden and
Unexpected Episodes of Rapid Heart Rate
that Start and Stop withoutWarning

76. Atrial Flutter
 A condition in which the Heart's Upper
Chambers (Atria) BeatToo Quickly

77. Atrial Fibrillation
 An Irregular, often Rapid Heart Rate that
commonly Causes Poor Blood Flow