1. BY DR. YVONNE KINYANJUI RUGARAMA HOSPITAL
LEARNING THE EKG
BY DR. YVONNE KINYANJUI
RUGARAMA HOSPITAL

2. LEARNING SESSIONS - simplified
Introduction – Cardiac anatomy, understanding the EKG, Interpreting the rhythm strips.
Rhythm i.e. arrhythmias – Irregular rhythms, escape and premature beats, Rapid ectopic rhythms, heart blocks.
Axis and hypertrophy – Lt. & Rt. Atrial hypertrophy and Lt. & Rt. Ventricular hypertrophy
Myocardial infarction

3. INTRODUCTION TO EKG

4. OBJECTIVES Basic cardiac anatomy and physiology. What is an EKG?
Interpreting a rhythm strip.

5. BASIC CARDIAC ANATOMY AND PHYSIOLOGY
THE HEART IS LIKE A CONE THAT HAS FALLEN OVER.

6. BASIC CARDIAC ANATOMY AND PHYSIOLOGY

7. BASIC CARDIAC ANATOMY AND PHYSIOLOGY

8. BASIC CARDIAC ANATOMY AND PHYSIOLOGY

9. BASIC CARDIAC ANATOMY AND PHYSIOLOGY

10. WHAT IS AN EKG?
Electrocardiograph – is the instrument that records the electrical activity of the heart.
Electrocardiogram (ECG) is the record of that activity.

11. 12 lead EKG tracing

12. WHAT IS AN EKG? 2 types of EKGs: single and 12 lead.
Can also have ambulatory, resting and stress EKG.
The standard EKG is made up of 12 separate leads (chest and limb leads) which are found on 2 planes (horizontal and frontal).

13. LEADS AND PLANES
To understand the EKG, we must understand leads and planes.
An EKG records information about the waveforms from different views or perspectives. These perspectives are the leads and planes.

14. LEADS
Provide a view of the heart’s electrical activity between one positive pole and one negative pole.
An imaginary line lies between the two poles and forms the lead’s axis.
Limb leads: I, II, III, aVL, aVR, aVF.
Chest leads: V1 to V6.

15. LIMB LEADS

16. LIMB LEADS

17. CHEST LEADS

18. LEADS

19. PLANES
A cross-sectional perspective of the heart’s electrical activity.
2 planes: Frontal (ant to post view) and Horizontal(superior or inferior view).

20. PLANES

21. WHAT IS AN EKG?
The heart’s electrical activity produces currents that radiate through the surrounding tissue to the skin.
Electrodes attached to the skin sense those electrical currents and send them to an EKG monitor.
The currents are then transformed into waveforms that represent the heart’s depolarization-repolarization cycle.

22. INTERPRETING A RHYTHM STRIP
THE ECG GRID

23. INTERPRETING A RHYTHM STRIP

24. THE P WAVE 1st component of a normal EKG waveform.
Represents atrial depolarization.
Look especially at:
Location
Configuration
Deflection

25. THE P WAVE A normal P wave: Location: Precedes the QRS complex
Amplitude: 2 to 3 mm high
Duration: 0.06 to 0.12 seconds
Configuration: Usually rounded and upright
Deflection: +ve in I, II, aVF, V2. Usually +ve but may vary in III and aVL. –ve in aVR. Biphasic in V1.

26. THE PR INTERVAL
Tracks the atrial impulse from the atria through the AVN, Bundle of His and the bundle branches.
Look especially at the duration.
A normal PR interval:
Location: From beginning of the P wave to the beginning of the QRS complex.
Duration: 0.12 – 0.20 seconds.

27. THE QRS COMPLEX Follows the P wave.
Represents depolarization of the ventricles.
Look especially at:
Duration
Configuration

28. THE QRS COMPLEX A normal QRS complex:
Location: Follows the PR interval.
Amplitude: 5-30mm high.
Duration: seconds
Configuration: Consists of the Q wave (1st –ve deflection, R wave (+ve deflection) and the S wave (2nd –ve deflection).
Deflection:+ve in I, II, III, aVL, aVF, V4, V5, V6. –ve in aVR, V1, V2, V3.

29. THE ST SEGMENT
Represents the end of ventricular depolarization and the start of ventricular repolarization.
Look especially at:
Deflection

30. THE ST SEGMENT A normal ST segment has:
Location: Extends from the end of the S wave to the beginning of the T wave.
Deflection: Usually isoelectric.

31. THE T WAVE Represents ventricular relaxation. Look especially at:
Amplitude
Configuration
Deflection

32. THE T WAVE A normal T wave has: Location: follows the S wave.
0.5mm in I, II, III and up to 10mm in the chest leads.
Configuration: Typically rounded and smooth.
Deflection: Usually upright in I, II, V3, V4, V5, V6. Inverted in aVR. Variable in the others.

33. THE QT INTERVAL
Measures ventricular depolarization and repolarization.
Length varies with heart rate.
Look especially at:
Duration.
A normal QT interval has:
Location: from start of QRS to end of T.
Duration: Usually 0.36 – 0.44 seconds

34. THE U WAVE Recovery period of the purkinje tissues.
Not always present.
Look especially at:
Configuration
A normal U wave has:
Location: After the T wave.
Configuration: Typically upright and rounded.
Deflection: Upright

35. 8-STEP METHOD OF RHYTHM STRIP INTERPRETATION
Check the rhythm
Calculate the rate
Evaluate the P wave
Check out the P to R
Now check out the Q to R to S
Talk to the T wave
On to the QT ...
Oh, yes, and don’t forget...

36. ...IN DETAIL Check the rhythm Calculate the rate Evaluate the P wave
How irregular is the rhythm? Is it slightly or markedly irregular? Does the irregularity occur in a pattern?
Calculate the rate
Evaluate the P wave
Are P waves present? Do they all have a normal configuration? Are they all of similar size and shape? Does every P have a QRS?

37. ...IN DETAIL Check out the P to R Now check out the Q to R to S
Is the duration a normal 0.12 – 0.20 sec? Is the PR interval constant?
Now check out the Q to R to S
Is the duration a normal <0.12 sec? Are all QRS’s the same size and shape? Does a QRS appear after every P wave?

38. ...IN DETAIL Talk to the T wave On to the QT
Are T waves present? Do they all have a normal shape and normal amplitude?
On to the QT
Is the duration a normal 0.36 – 0.44 sec?
Oh yes, and don’t forget...
Check for ectopic beats and other abnormalities. Check the ST segment. Look for the presence of a U wave.

39. ...IN DETAIL
Finish by noting your findings, and then interpret them by naming the rhythm strip according to one or all of these findings:
Origin of the rhythm
Rate xtics
Rhythm abnormalities

40. RATE

41. CALCULATING THE RATE 4 methods
10 x method (uses a 6 second strip).
1,500 method
Sequence method
The rate calculator
Be mindful of the recording speed (calibration)

42. CALCULATING THE RATE THE 10 X METHOD
Easiest way. Not as accurate as other methods.
Best for irregular rhythms and bradycadias (<60b/m).
Ten 6 second strips = 1 min
Atrial rate: Number of P’s in 6 second strip multiplied by 10.
Ventricular rate: Number of R’s in 6 second strip multiplied by 10.

43. CALCULATING THE RATE 1,500 METHOD
Can’t be used if heart rate is irregular.
Needs MATHS CALCULATION 
1500 small squares = 1 min.
Count small squares between identical points on 2 consecutive P and R waves to get atrial and ventricular rates respectively by dividing 1500 by that number.

44. CALCULATING THE RATE SEQUENCE METHOD
Fastest and only used with Regular rythms.
Requires memorization of a sequence of numbers corresponding to the heavy black vertical lines on the EKG.

45. NOW ON TO THE PRACTICE RHYTHM STRIPS...

46. RHYTHM

47. OBJECTIVES Definition of arrhythmia
How to tell if a rhythm is regular or irregular
Review the heart’s conduction pathway.
Classification and discussion of arrhythmias.

48. DEFINITION OF ARRHYTHMIA
An abnormal or irregular rhythm of the heart.
A.K.A dysrhythmia

49. ASSESSING RHYTHM Use the For atrial rhythm: measure P-P interval
Caliper method
Paper and pencil method.
For atrial rhythm: measure P-P interval
For ventricular rhythm: measure R-R interval (Or can use Q or S waves)
Variations of up to 0.04sec considered normal.

50. RHYTHM

51. INHERENT RATES Sino-atrial node: 60 -100 b/m Atrial foci: 60 – 80 b/m
AV junctional foci: 40 – 60 b/m
Ventricular foci: 20 – 40 b/m

52. RECOGNIZING A NORMAL SINUS RHYTHM
A normal sinus rhythm is the standard against which all other rhythms are compared.
Xtics of a normal sinus rhythm (using 8-step method)
Atrial and Ventricular rhythms are regular
Atrial and Ventricular rates are between 60 – 100b/m and all impulses are conducted to the ventricles
P waves are rounded, smooth and upright. And for every P there is a QRS.

53. RECOGNIZING A NORMAL SINUS RHYTHM
PR interval is normal (0.12 – 0.20)
QRS is of normal duration (<0.12sec)
The T wave is upright.
The QT is within normal limits (0.36 – 0.44 seconds).
No ectopic or aberrant beats are occurring.

55. TYPES OF ARRHYTHMIAS Four Categories: 1. Irregular rhythms
2. Escape & Premature beats
3. Rapid ectopic rhythms
4. Heart Blocks

56. IRREGULAR RHYTHMS Sinus Arrhythmia Wandering Pacemaker
Atrial Fibrillation

57. SINUS ARRHYTHMIA Irregular Pacemaking is still from sinus node
All P waves are the same
QRS and T wave are normal appearing
Changes seen during inspiration and expiration

58. WANDERING PACEMAKER
Irregular due to pacing from a variety of atrial foci(pacemaking activity wanders from focus to focus)
P waves take different shapes
If rate is >100, it is called multifocal atrial tachycardia

59. ATRIAL FIBRILLATION Irregularly irregular
Rapid firing of multiple foci in the atria
No single impulse depolarizes the entire atria
Only the occasional impulse gets through to the AV node to stimulate the ventricles
Ventricular response may produce rapid or slow ventricular rate

60. ESCAPE & PREMATURE BEATS
ESCAPE BEAT
Response to a pause in cardiac activity
Atrial escape beat
Junctional escape beat
Ventricular escape beat
PREMATURE BEAT
A focus discharging earlier than expected
Premature atrial beat
Premature junctional beat
Premature ventricular contraction

61. ATRIAL ESCAPE BEAT Pause in the SA node Atrial ectopic focus “escapes”
Visible pause on ECG
P wave looks different
QRS the same

62. JUNCTIONAL ESCAPE BEAT
Escape beat originates in the AV junction
No P wave or inverted from retrograde atrial stimulation
QRS the same- ventricles still stimulated through ventricular conduction system

63. VENTRICULAR ESCAPE BEAT
Escape beat originates in a ventricular ectopic focus
No P wave
Get an enormous QRS complex (slower conduction)

64. NOTE!!!
SINUS ARREST – occurs when a sick SAN’s pacemaking activity is suddenly “arrested” and does not send out pacemaking stimuli.
After a pause of sinus arrest, a new pacemaking area assumes the pacing responsibility, and forms the escape rhythm.
If the junctional and ventricular escape rhythms accelerate above their inherent rates, they become accelerated idio-junctional and accelerated idio-ventricular rhythms.

65. ESCAPE & PREMATURE BEATS
ESCAPE BEAT
Response to a pause in cardiac activity
Atrial escape beat
Junctional escape beat
Ventricular escape beat
PREMATURE BEAT
A focus discharging earlier than expected
Premature atrial beat
Premature junctional beat
Premature ventricular contraction

66. PREMATURE ATRIAL BEAT From an ectopic focus in the atria
P wave looks different, not from the SA node

67. PREMATURE JUNCTIONAL BEAT
From an ectopic focus in the AV node
No P wave or inverted from retrograde atrial stimulation
QRS looks the same

68. PREMATURE VENTRICULAR CONTRACTION
From ectopic focus in the ventricles
Produces pulse beat earlier and usually weaker than normal.
Wide QRS (slower conduction)
No P wave
Usually followed by a
compensatory pause.

69. PREMATURE VENTRICULAR CONTRACTION...
Interpolated PVCs: sandwiched between the normal beats. Produce no compensatory pause and no disturbance in the rhythm

70. PREMATURE VENTRICULAR CONTRACTION...

71. PREMATURE VENTRICULAR CONTRACTION...
Unifocal: Identical PVCs originating from the same focus.

72. PREMATURE VENTRICULAR CONTRACTION...
Multifocal: PVCs from different ventricular foci. Appear different.

73. PREMATURE VENTRICULAR CONTRACTION...
Multifocal:
Considered a dangerous rhythm, especially in patients with recent myocardial infarction
Risk of developing ventricular tachycardia is high

74. PREMATURE VENTRICULAR CONTRACTION...
Can be numerous, but >6 per minute can be pathologic
Can indicate poor coronary blood flow or:
Stimulants, meds, hypoxia can set off PVC’s

75. PREMATURE VENTRICULAR CONTRACTION...
If coupled with 1 normal cycle, called Ventricular Bigeminy
If found in a 2:1 cycle, called Ventricular Trigeminy

76. PREMATURE VENTRICULAR CONTRACTION...
VENTRICULAR PARASYSTOLE
Dual rhythm caused by 2 pacemakers
One is the ventricular ectopic focus which produces PVC like QRS complexes at a generally slow rate.
The other is a supraventricular focus (SAN or AV junction).
Appear like PVCs coupled to a long series of normal beats.

77. PREMATURE VENTRICULAR CONTRACTION...
VENTRICULAR PARASYSTOLE

78. PREMATURE VENTRICULAR CONTRACTION...
A single ectopic focus may produce a run of 3-6 PVC’s
Considered more serious pathology
Is called a “run of ventricular tachycardia” (v. tach) if more than 3 beats

79. PREMATURE VENTRICULAR CONTRACTION...
PVC can occur during a T wave
Dangerous event
Called “R on T”

80. RAPID ECTOPIC RHYTHMS From ectopic focus pacing rapidly
Sometimes have more than 1 ectopic focus involved.

81. RAPID ECTOPIC RHYTHMS Paroxysmal Tachycardia - 150-250 beats/min
Flutter beats/min
Fibrillation beats/min
** Dx: If possible, mention rate and location of ectopic focus responsible.

82. PAROXYSMAL (SUDDEN) TACHYCARDIA
Rates of b/m.
Usually arises spontaneously from an ectopic focus.
Sinus tachycardia (caused by meds, exercise, excitement, shock) not a paroxysmal tachycardia.

83. PAROXYSMAL TACHYCARDIA
First confirm rate ( b/m)
Then determine location of ectopic focus

84. PAROXYSMAL ATRIAL TACHYCARDIA
Ectopic atrial focus
P wave looks different from those before the tachycardia.
QRS and T waves preserved

85. PAROXYSMAL ATRIAL TACHYCARDIA WITH BLOCK
More than 1 P wave before QRS
P waves small and spiked and upwards in leads II and III
Often seen in digitalis toxicity

86. PAROXYSMAL JUNCTIONAL TACHYCARDIA
Rate b/m
Ectopic focus from AV junction
No P wave or inverted P wave

87. SUPRAVENTRICULAR TACHYCARDIA
Paroxysmal atrial and junctional tachycardia together are called supraventricular tachycardia
Both can look alike on ECG as P wave can merge with T wave and be unidentifiable
Both are treated the same, so differentiating not critical

88. PAROXYSMAL VENTRICULAR TACHYCARDIA
Rate b/m
Ectopic ventricular focus
Atria are still depolarizing, but hard to see P waves (AV Dissociation)

89. PAROXYSMAL VENTRICULAR TACHYCARDIA
Presence of Capture and Fusion beats confirms the diagnosis of PVT.

90. PAROXYSMAL VENTRICULAR TACHYCARDIA
Runs of ventricular tachycardia often signify coronary artery disease or hypoxia

91. TORSADES DE POINTES Form of ventricular tachycardia
Quinidine toxicity is the most common cause

92. FLUTTER
Rate
Either atrial or ventricular ectopic focus

93. ATRIAL FLUTTER Rapid, identical P waves
Dx most often made based on appearance rather than rate. Saw tooth appearance of P waves.

94. VENTRICULAR FLUTTER Rate 250-350
Single ventricular ectopic focus firing at a rapid rate
Deteriorates into deadly arrhythmias
Ventricles contracting 5/sec
Blood unable to fill the ventricles, coronary arteries fail to get blood
Multiple ventricular ectopic foci try to compensate, turns into ventricular fibrillation

95. VENTRICULAR FLUTTER

96. FIBRILLATION Rate 350-450 b/m Multiple foci rapidly discharging
Chambers not contracting, only twitching
Waves not distinguishable
Can be either atrial or ventricular

97. ATRIAL FIBRILLATION No P waves discernable
Pebble in water vs rain in water
Ventricular rate – use 6 second strip to calculate

98. ATRIAL FIBRILLATION
NORMAL RHYTHM FROM SAN
ATRIAL FIBRILLATION

99. VENTRICULAR FIBRILLATION
Erratic, irregular ECG tracing
If you can recognize a pattern, probably not ventricular fibrillation
No cardiac pumping, dire emergency

100. HEART BLOCKS
SINUS BLOCK
AV BLOCK
BUNDLE BRANCH BLOCK
HEMIBLOCK

101. HEART BLOCKS Electrical block
Prevents or slows electrical stimuli and depolarization
One patient may have multiple types of block

102. SINUS BLOCK SA node fails to pace for at least one cycle, then resumes
All P waves look the same
May see an escape beat

103. SINUS BLOCK VERSUS SINUS ARREST

104. AV BLOCK AV node slows or stops depolarization of ventricles
Get a prolonged PR interval or a P wave without a QRS
Can be 1˚, 2˚, or 3˚

105. FIRST DEGREE AV BLOCK PR interval prolonged – greater than 0.2 seconds
Remains consistent with each heart cycle

106. SECOND DEGREE AV BLOCK TYPE 1 – WENCKEBACH
PR interval becomes progressively longer, until QRS is dropped (AV node not penetrated)

107. SECOND DEGREE AV BLOCK TYPE 2 – MOBITZ 2
PR interval does not become progressively longer, but still see a QRS dropped
PR intervals normal before and after dropped QRS. P waves at a normal rate.
Often signals a more serious conduction problems
Different from sinus block (which lacks a P wave)

108. SECOND DEGREE AV BLOCK
Can get a 2:1 AV Mobitz 2 block

109. SECOND DEGREE AV BLOCK
Or a 3:1 AV Mobitz 2 block

110. THIRD DEGREE AV BLOCK Complete block
No atrial impulse reaches the ventricles
Ventricles paced independently
QRS will either be junctional paced or ventricular
Junctional rhythm is 40-60, Ventricular 20-40
Ventricular rate can be so slow that brain does not receive enough blood and patient loses consciousness – Stokes-Adams syndrome

111. THIRD DEGREE AV BLOCK

112. BUNDLE BRANCH BLOCK
Right and left bundle branches normally depolarize at the same time
During a branch block, one branch depolarizes more slowly – causes 2 “joined QRSs” i.e. 2 out of sync QRSs superimposed.

113. BUNDLE BRANCH BLOCK
Get an R and R`
QRS is prolonged ≥ 0.12 sec

114. BUNDLE BRANCH BLOCK RIGHT LEFT Look at leads V1 and V2

115. BUNDLE BRANCH BLOCK Left BBB would block hide the presence of a Q wave
Cannot rely on ECG to diagnose infarction in the presence of left BBB

116. WOLFF – PARKINSON - WHITE
Accessory pathway around the AV node
Causes apparent shortening of PR interval and prolonged QRS
Can get paroxysmal tachycardia

117. NOW FOR MORE PRACTICE...