This document provides an overview of electrocardiography (ECG), including basics of the cardiac conduction system, ECG leads and recording methodology, normal ECG waveforms and intervals, cardiac arrhythmias, and pacemakers. Key topics covered include the standard 12-lead ECG, techniques for interpreting rate, rhythm, intervals, and axis, common normal variants and abnormalities, types of arrhythmias including sinus, atrial, and ventricular rhythms, and basics of cardiac pacemaker function. The document serves as an educational guide for understanding ECGs and their clinical applications.

1. DR. PALLAB KANTI NATH
MBBS, MD (ANESTHESIOLOGY)
CONSULTANT PAIN MEDICINE, ANESTHESIOLOGIST,
INTENSIVIST
Basics of Electrocardiography,
Arrhythmia & Pacemaker

2. What will we learn?
1. Basics of the conduction system of heart
2. ECG leads and recording methodology
3. ECG waveforms and intervals
4. Normal ECG and its variants
5. Interpretation and reporting of an ECG
6. Cardiac Arrhythmia
7. Cardiac Pacemaker

4. What is an ECG?
Recording of the electrical activity heart.
Graph of voltage versus time

5. Recording an ECG

6. BasicsBasics
ECG graph:
1 mm Small squares
5 mm Large squares
Paper Speed:
25 mm/sec standard
Voltage Calibration:
10 mm/mV standard

7. ECG Paper: DimensionsECG Paper: Dimensions
5 mm
1 mm
0.1 mV
0.04 sec
0.2 sec
Speed = rate
Voltage
~Mass

8. ECG Leads
Leads are electrodes which measure the potential
difference between:
1. Two different points on the body (bipolar
leads)
2. One point on the body and a virtual reference
point with zero electrical potential, located in
the center of the heart (unipolar leads)

9. ECG Leads
The standard ECG has 12 leads: 3 Standard Limb Leads
3 Augmented Limb Leads
6 Precordial Leads

10. Einthoven's triangle

11. Precordial Leads

12. Electrode name Electrode placement
RA On the right arm, avoiding thick muscle.
LA On the left arm, avoiding thick muscle.
RL On the right leg, lateral calf muscle.
LL On the left leg, lateral calf muscle.
V1
In the fourth intercostal space (between ribs 4 and 5) just
to the right of the sternum (breastbone).
V2
In the fourth intercostal space (between ribs 4 and 5) just
to the left of the sternum.
V3 Between leads V2 and V4.
V4 5th Intercostal space at the midclavicular line
V5 Anterior axillary line at the same level as V4
V6 Midaxillary line at the same level as V4 and V5

13. Arrangement of Leads on the ECG

14. Arrangement on an ECG strip

15. Normal standardization
1 mV=10 mm
Will result in perfect right angles at each corner

16. Overdamping and Underdamping
Overdamping: When the pressure of the stylus is too firm
on the paper so that it’s movements are retarded –
deflection fractionally wider and diminished amplitude
Unerdamping: When the writing stylus is not pressed
firmly enough against the paper - sharp spikes at the
corners

17. Standard sites unavailableAmputation/
burns/
bandages
leads should
be placed as
closely as
possible to
the standard
sites

18. Specific cardiac abnormalities
dextrocardia right & left arm electrodes should be
reversed
pre-cordial leads should be recorded from V1R(V2)
to V6

19. Continuous monitoring
Bed side

20. Continuous monitoring
Holter monitoring

21. Continuous monitoring
TMT

22. Artefacts on ECG
Distorted signals caused by secondary internal or external
sources, such as muscle movement or interference from an
electrical device.

23. ECG Artefacts
ECG tracing is affected by patient’s motion.
rhythmic motions (shivering or tremors) can create
the illusion of arrhythmia.
May lead to:
Altered diagnosis, treatment, outcome of
therapy and legal liabilities

24. Reducing Artefacts during an ECG
Patient Positioning
Supine or semi-Fowler’s position.
 If patient can’t tolerate lying flat, do the ECG in a more upright
position.
Instruct patient to place arms down by his side and
to relax the shoulders.
Patient’s legs should be uncrossed.
Place electrical devices, such as cell phones, away
from the patient as they may interfere with the
machine.

25. Reducing Artefacts during an ECG
Skin Preparation
Dry the skin if it’s moist or diaphoretic.
Shave any hair that interferes with electrode
placement.
 ensures a better electrode contact with the skin.
Rub an alcohol prep pad or benzoin tincture on the
skin to remove any oils and help with electrode
adhesion.

26. Reducing Artefacts during an ECG
Electrode Application
Check the electrodes to make sure the gel is still
moist.
Do not place the electrodes over bones.
Do not place the electrodes over areas where there is
a lot of muscle movement.

27. Interpretation of an ECG
Heart Rate
Rhythm
Axis
Wave morphology
Intervals and segments analysis
Specific changes (If any)

29. Determining the Heart Rate
Rule of 300
10 Second Rule

30. Rule of 300
Divide 300 by the number of “big boxes” between
neighboring QRS complexes
The result will be approximately equal to the rate
Although fast, this method only works for regular
rhythms.

31. Rule of 300

32. The Rule of 300
It may be easiest to memorize the following table:
# of big# of big
boxesboxes
Rate (appx)Rate (appx)
11 300300
22 150150
33 100100
44 7575
55 6060
66 5050

33. 10 Second Rule
As most ECGs record 10 seconds of rhythm per
page, one can simply count the number of beats
present on the ECG and multiply by 6 to get the
number of beats per 60 seconds.
This method works well for irregular rhythms.

34. 10 Second Rule

35. QRS axis
The QRS axis represents the net overall direction of the
heart’s electrical activity.
Abnormalities of axis can hint at:
Ventricular enlargement
Conduction blocks (i.e. hemiblocks)

36. The QRS Axis
By near-consensus, the
normal QRS axis is defined
as ranging from -30° to +90°.
-30° to -90° is referred to as a
left axis deviation (LAD)
+90° to +180° is referred to as
a right axis deviation (RAD)

37. Determining the Axis
The Quadrant Approach
The Equiphasic Approach

38. Determining the Axis
Predominantly
Positive
Predominantly
Negative
Equiphasic

39. The Quadrant Approach
Examine the QRS complex in leads I and aVF to determine
if they are predominantly positive or predominantly
negative. The combination should place the axis into one
of the 4 quadrants below.

40. Using leads I, II, III
LEAD 1LEAD 1 LEAD 2LEAD 2 LEAD 3LEAD 3
NormalNormal UPRIGHTUPRIGHT UPRIGHTUPRIGHT UPRIGHTUPRIGHT
PhysiologicaPhysiologica
l Left Axisl Left Axis
UPRIGHTUPRIGHT
UPRIGHT /UPRIGHT /
BIPHASICBIPHASIC
NEGATIVENEGATIVE
PathologicalPathological
Left AxisLeft Axis
UPRIGHTUPRIGHT NEGATIVENEGATIVE NEGATIVENEGATIVE
Right AxisRight Axis NEGATIVENEGATIVE
UPRIGHTUPRIGHT
BIPHASICBIPHASIC
NEGATIVENEGATIVE
UPRIGHTUPRIGHT
ExtremeExtreme
Right AxisRight Axis
NEGATIVENEGATIVE NEGATIVENEGATIVE NEGATIVENEGATIVE

41. Common causes of LAD
May be normal in the elderly and very obese
High diaphragm during pregnancy, ascites, or Abdominal
tumors
Inferior wall MI
Left Anterior Hemiblock
Left Bundle Branch Block
WPW Syndrome
Emphysema

42. Common causes of RAD
Normal variant
Right Ventricular Hypertrophy
Anterior MI
Right Bundle Branch Block
Left Posterior Hemiblock
WPW Syndrome

43. The himalayan p wave
Combined tricuspid and pulmonic stenosis
 P waves are tall (> 5 mm) and peaked in lead II
Caused by reflected dilated right atrium resulting
from pressure overloading

44. Normal Sinus Rhythm
Originates in the SA node
Rate between 60 and 100 beats per min
Tallest p waves in Lead II
Monomorphic P waves
Normal PR interval of 120 to 200 msec
Normal relationship between P and QRS
Some sinus arrhythmia is normal

45. Normal QRS complex
Completely negative in lead aVR , maximum positivity in
lead II
rS in right oriented leads and qR in left oriented leads
(septal vector)
Transition zone commonly in V3-V4
RV5 > RV6 normally
Normal duration 50-110 msec, not more than 120 msec
Physiological q wave not > 0.03 sec

46. QRS Complex

47. Amplitude of QRS
Formed by electrical force generated by the
ventricular myocardium
Depends on:
 distance of the sensing electrode from the
ventricles
 Body build - a thin individual has larger
complexes when compared to obese individuals

48. Normal T wave
Same direction as the preceding QRS complex
Blunt apex with asymmetric limbs
Height < 5mm in limb leads and <10 mm in
precordial leads
Smooth contours
May be tall in athletes

49. QT interval
The beginning of the QRS complex is best determined in a
lead with an initial q wave
 leads I,II, avL ,V5 or V6
QT interval shortens with tachycardia and lengthens with
bradycardia
Normal 350 to 430 msec
With a normal heart rate (60 to 100), the QT interval
should not exceed half of the R-R interval roughly

50. QT Interval

51. Reporting an ECG

52. “ WHOSE ECG IS IT ?!”
1. Patient Details

53. “IS IT PROPERLY TAKEN ?”
2. Standardisation and lead
placement

55. NORMAL OR ABNORMAL?
4. Segment and wave form
analysis

56. “ DOES THE ECG CORRELATE WITH
THE CLINICAL SCENARIO ?”
Final Impression

57. Cardiac
Arrhythmias

58. SA Node
 The primary pacemaker of the
heart
 Each normal beat is initiated by
the SA node
 Inherent rate of 60-100 beats per
minute
 Represents the P-wave in the
QRS complex or atrial
depolarization (firing)

59. AV Node
– Located in the septum of
the heart
– Receives impulse from
inter-nodal pathways
and holds the signal
before sending on to the
Bundle of His
– Represents the PR
segment of the QRS
complex

60. AV Node
– Represents the PR segment of the cardiac
cycle
– Has an inherent rate of 40-60 beats per
minute
– Acts as a back up when the SA node fails
– Where all junctional rhythms originate

61. QRS Complex
• Represents the
ventricles
depolarizing (firing)
collectively. (Bundle
of His and Perkinje
fibers)
• Origin of all
ventricular rhythms
• Has an inherent rate
of 20-40 beats per
minute

62. – P wave = atrial depolarization
– PR interval = pause between atrial and
ventricular depolarization
– QRS = ventricular depolarization
– T wave = ventricular repolarization
Cardiac cycle

63. Normal Sinus Rhythm
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
60 -
100
Regular
Before each QRS,
Identical
.12 - .20 <.12
Sinus Rhythms

64. • Normal Sinus Rhythm
– Sinus Node is the primary pacemaker
– One upright uniform p-wave for every QRS
– Rhythm is regular
– Rate is between 60-100 beats per minute
Sinus Rhythms

65. Sinus Bradycardia
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
<60 Regular
Before each QRS,
Identical
.12 - .20 <.12
Sinus Rhythms

66. • Sinus Bradycardia
– One upright uniform p-wave for every QRS
– Rhythm is regular
– Rate less than 60 beats per minute
• SA node firing slower than normal
• Normal for many individuals
• Identify what is normal heart rate for patient
Sinus Rhythms

67. •
Sinus Tachycardia
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
>100 Regular
Before each QRS,
Identical
.12 - .20 <.12
Sinus Rhythms

68. • Sinus Tachycardia
– One upright uniform p-wave for every QRS
– Rhythm is regular
– Rate is greater than 100 beats per minute
• Usually between 100-160 (>160 SVT)
• Can be high due to anxiety, stress, fever,
medications (anything that increases oxygen
consumption)
Sinus Rhythms

69. Sinus Arrhythmia
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Var. Irregular
Before each QRS,
Identical
.12 - .20 <.12
Sinus Rhythms

70. • Sinus Arrhythmia
– One upright uniform p-wave for every QRS
– Rhythm is irregular
• Rate increases as the patient breathes in
• Rate decreases as the patient breathes out
– Rate is usually 60-100 (may be slower)
– Variation of normal, not life threatening
Sinus Rhythms

71. Sinus Arrest
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
NA Irregular
Before each QRS,
Identical
.12 - .20 <.12
Sinus Rhythms

72. Sinus Rhythms
Stop of sinus rhythm
New rhythm starts
One dropped beat is a sinus pause
Beats walk through
Sinus Pause

73. Premature Atrial Contraction (PAC)
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
NA Irregular
Premature &
abnormal or
hidden
.12 - .20 <.12
Atrial Rhythms

74. – Premature Atrial Contraction (PAC)
• One P-wave for every QRS
– P-wave may have different morphology on ectopic
beat, but it will be present
• Single ectopic beat will disrupt regularity of
underlying rhythm
• Rate will depend on underlying rhythm
• Underlying rhythm must be identified
• Classified as rare, occasional, or frequent
PAC’s based on frequency
Atrial Rhythms

75. Atrial Fibrillation
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Var. Irregular Wavy irregular NA <.12
Atrial Rhythms

76. • Atrial Fibrillation
– No discernable p-waves preceding the QRS
complex
• The atria are not depolarizing effectively, but fibrillating
– Rhythm is grossly irregular
– If the heart rate is <100 it is considered controlled
a-fib, if >100 it is considered to have a “rapid
ventricular response”
– AV node acts as a “filter”, blocking out most of the
impulses sent by the atria in an attempt to control
the heart rate
Atrial Rhythms

77. • Atrial Fibrillation (con’t)
– Often a chronic condition, medical
attention only necessary if patient becomes
symptomatic
– Patient will report history of atrial
fibrillation.
Atrial Rhythms

78. Atrial Flutter
Heart Rate Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Atrial=250
– 400
Ventricular
Var.
Irregular Sawtooth
Not
Measur-
able
<.12
Atrial Rhythms

79. • Atrial Flutter
– More than one p-wave for every QRS complex
• Demonstrate a “sawtooth” appearance
– Atrial rhythm is regular. Ventricular rhythm will be
regular if the AV node conducts consistently. If the
pattern varies, the ventricular rate will be irregular
– Rate will depend on the ratio of impulses
conducted through the ventricles
Atrial Rhythms

80. Atrial Rhythms
• Atrial Flutter
– Atrial flutter is classified as a ratio of p-
waves per QRS complexes (ex: 3:1 flutter
3 p-waves for each QRS)
– Not considered life threatening, consult
physician is patient symptomatic

81. • Rhythms that originate at the AV
junction
• Junctional rhythms do not have
characteristic p-waves.
Junctional Rhythms

82. Premature Junctional Contraction PJC
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Usually
normal
Irregular
Premature,
abnormal, may be
inverted or hidden
Short
<.12
Normal
<.12
Junctional Rhythms

83. • Premature Junctional Contraction (PJC)
– P-wave can come before or after the QRS complex,
or it may lost in the QRS complex
• If visible, the p-wave will be inverted
– Rhythm will be irregular due to single ectopic beat
– Heart rate will depend on underlying rhythm
– Underlying rhythm must be identified
– Classify as rare, occasional, or frequent PJC based
on frequency
– Atria are depolarized via retrograde conduction
Junctional Rhythms

84. Accelerated Junctional
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Var. Regular
Inverted, absent or
after QRS
<.12 <.12
Junctional Rhythms

85. • Accelerated Junctional Rhythm
– P-wave can come before or after the QRS
complex, or lost within the QRS complex
• If p-waves are seen they will be inverted
– Rhythm is regular
– Heart rate between 60-100 beats per minute
• Within the normal HR range
• Fast rate for the junction (normally 40-60 bpm)
Junctional Rhythms

86. Junctional Tachycardia
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
>100 Regular
May be inverted or
hidden
Short
<.12
Normal
<.12
Junctional Rhythms

87. • Junctional Tachycardia
– P-wave can come before or after the QRS complex or
lost within the QRS entirely
• If a p-wave is seen it will be inverted
– Rhythm is regular
– Rate is between 100-180 beats per minute
• In the tachycardia range, but not originating from SA node
– AV node has sped up to override the SA node for
control of the heart
Junctional Rhythms

88. Junctional Rhythms
Junctional Escape
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
40 –
60
Regular
Absent, inverted
or after QRS
Short
<.12
Normal
<.12

89. Junctional Rhythms
• Junctional Escape Rhythm
– P-wave may come before or after the QRS
or may be hidden in the QRS entirely
• If p-waves are seen, they will be inverted
– Rhythm is regular
– Rate 40-60 beats per minute
• The SA node has failed; the AV junction takes
over control of the heart

90. Ventricular Rhythms
Premature Ventricular Contraction (PVC)
Heart
Rate
Rhythm P Wave
PR
Interval
(sec.)
QRS
(Sec.)
Var. Irregular
No P waves
associated with
premature beat
NA
Wide
>.12

91. Ventricular Rhythms
• Premature Ventricular Contraction (PVC)
– The ectopic beat is not preceded by a p-wave
– Irregular rhythm due to ectopic beat
– Rate will be determined by the underlying rhythm
– QRS is wide and may be bizarre in appearance
– Caused by a irritable focus within the ventricle
which fires prematurely
– Must identify an underlying rhythm

92. Ventricular Rhythm
• Premature Ventricular Contraction
– Classify as rare, occasional, or frequent
– Classify as unifocal, or multifocal PVC’s
• Unifocal-originating from same area of the
ventricle; distinguished by same morphology

93. Ventricular Rhythm
• Premature Ventricular Contraction
– Classify as unifocal, or multifocal PVC’s
– Unifocal-originating from same area of the
ventricle; distinguished by same morphology
– Multifocal-originating from different areas of the
ventricle; distinguished by different morphology

94. Ventricular Rhythm
• Premature Ventricular Contraction
– Bigeminy
• A PVC occurring every other beat
– Also seen as Trigeminy, Quadrigeminy

95. Ventricular Rhythm
• Dangerous PVC’s
– R on T
– Runs of PVC’s
– 3 or more
considered Vtach

96. Ventricular Rhythms
Ventricular Tachycardia
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
100 –
250
Regular
No P waves
corresponding to QRS,
a few may be seen
NA >.12

97. Ventricular Rhythms
• Ventricular Tachycardia
– No discernable p-waves with QRS
– Rhythm is regular
– Atrial rate cannot be determined,
ventricular rate is between 150-250 beats
per minute
– Must see 4 beats in a row to classify as v-
tach

98. Ventricular Rhythms
Ventricular Fibrillation
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
0 Chaotic None NA None

99. Ventricular Rhythms
• Ventricular Fibrillation
– No discernable p-waves
– No regularity
– Unable to determine rate
– Multiple irritable foci within the ventricles all
firing simultaneously
– May be coarse or fine
– This is a deadly rhythm
• Patient will have no pulse
• Call a code and begin CPR

100. Asystole
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
None None None None None

101. Asystole
• No p-waves
• No regularity
• No Rate
• This rhythm is associated with
death
– Check patient and leads
– No pulse
• Begin CPR

102. Heart Block
First Degree Heart Block
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.)
Norm. Regular
Before each QRS,
Identical
> .20 <.12

103. Heart Block
– First Degree Heart Block
• P-wave for every QRS
• Rhythm is regular
• Rate may vary
• Av Node hold each impulse longer than normal
before conducting normally through the
ventricles
• Prolonged PR interval
– Looks just like normal sinus rhythm

104. Heart Block
Second Degree Heart Block
Mobitz Type I (Wenckebach)
Heart
Rate
Rhythm P Wave
PR Interval
(sec.)
QRS
(Sec.
)
Norm.
can be
slow
Irregular
Present but some
not followed by
QRS
Progressively
longer
<.12

105. Heart Block
• Second Degree Heart Block
• Mobitz Type I (Wenckebach)
– Some p-waves are not followed by QRS
complexes
– Rhythm is irregular
• R-R interval is in a pattern of grouped beating
– Rate 60-100 bpm
– Intermittent Block at the AV Node
• Progressively prolonged p-r interval until a QRS is
blocked completely

106. Heart Block
Second Degree Heart Block
Mobitz Type II (Classical)
Heart
Rate
Rhythm P Wave
PR
Interval
(sec.)
QRS
(Sec.)
Usually
slow
Regular
or
irregular
2 3 or 4 before each
QRS, Identical
.12 - .20
<.12
depends

107. Heart Block
• Second Degree Heart Block
• Mobitz Type II (Classical)
– More p-waves than QRS complexes
– Rhythm is irregular
– Atrial rate 60-100 bpm; Ventricular rate 30-100
bpm (depending on the ratio on conduction)
– Intermittent block at the AV node
• AV node normally conducts some beats while blocking
others

108. Heart Block
Third Degree Heart Block
(Complete)
Heart
Rate
Rhythm P Wave
PR
Interval
(sec.)
QRS
(Sec.)
30 –
60
Regular
Present but no
correlation to QRS
may be hidden
Varies
<.12
depends

109. Heart Block
• Third Degree Heart Block (Complete)
– There are more p-waves than QRS
complexes
– Both P-P and R-R intervals are regular
– Atrial rate within normal range; Ventricular
rate between 20-60 bpm
– The block at the AV node is complete
• There is no relationship between the p-waves
and QRS complexes

110. Pacemaker

111. 113
Pacemakers Today
• Single or dual chamber.
• Multiple programmable features,
• Adaptive rate pacing.
• Programmable lead configuration.
Internal Cardiac Defibrillators (ICD)
• Trans-venous leads.
• Multi-programmable
• Incorporate all capabilities of contemporary
pacemakers.
• Storage capacity.

112. 114
Permanent Pacing Indications
• Complete heart block
• Chronic Bifascicular and Trifascicular Block.
• AV Block after Acute MI.
• 2nd
degree heart block / Mobiz type 2
• Hypersensitive Carotid Sinus and Neurally Mediated
Syndromes.
• Sick sinus syndrome( Sinus Node Dysfunction)
• Stroke Adams syndrome.
Indications for ICDs
• Cardiac arrest due to VT/VF not due to a transient or
reversible cause.
• Spontaneous sustained VT.
• Syncope with hemodynamically significant sustained
VT or VF

115. Pacer malfunction symptoms
1. Vertigo/Syncope
*Worsens with exercise
2. Unusual fatigue
3. Low B/P/ ↓ peripheral pulses
4. Cyanosis
5. Jugular vein distention
6. Oliguria
7. Dyspnea/Orthopnea
8. Altered mental status

116. Evaluation and preparation for Sx
• Indication for implanted pacemaker/ICD
– Sustained /intermittent tachyarrhythmia or bradyarrhythmias.
– Heart failure
• Type of device:
• Clinical indication of the device
• Appraisal of patient’s degree of dependence on the devices(for patient
requiring pacing for bradyarrhythmias)
• Assessment of device function,
– A preoperative history of vertigo, pre syncope, or syncope in a patient
with a pacemaker could reflect pacemaker dysfunction.
– A 10% decrease in heart rate from the initial heart rate setting may
reflect battery depletion.
– An irregular heart rate could indicate competition of the pulse generator
with the patient's intrinsic heart rate or failure of the pulse generator to
sense R waves.
• Continue antiarrythmic drug and other cardiac drugs as mandated
• Consider Electromagnetic and Mechanical Interference (EMI)

117. Monitoring
• Manual pulse palpation
• Pulse oximetry
• Continuous ECG monitoring
• Auscultation of heart sounds
• Intra-arterial blood pressure
Investigation:
• Routine investigation along with s. electrolytes/acid –
base analysis.
• Chest x-ray:
– Location and external condition of pacemaker electrodes.
– If bi-ventricular pace maker(position of coronary sinus lead
when insertion of central line or PA catheter planned ).

118. Management of a Patient --Intra Operatively
• Application of magnet over pulse generator of pace maker…
no longer an acceptable practice.
• Results in asynchronous fixed rate (chance of R on T
phenomenon)
• But Difficult to assess the effect of magnet on cardioverter-
defibrilator.
• Transcutaneous pacing is always kept ready.
• Rate responsive pacemakers should have
rate responsive mode disabled before
surgery.
• Central venous catheterisation: chance of pacing leads
dislodgement.

120. Factors affecting the pacing
threshold
Increase threshold
• 1-4 wks after implantation
• MI
• Hypothermia/Hypothyroid
ism
• Hyperkalaemia/acidosis/al
kalosis
• Antiarrhythmics(class
1a,1b,1c)
• Severe
hypoxia/hyperglycemia
• Inhalational –local
anaesthesia
Decrease threshold
• Increases catecholamines
• Stress, anxiety
• Sympathomimetic drugs
• Anticholinergics
• Glucocorticoids
• Hyperthyroidism
• Hypermetabolic status

121. Effects of Anesthetic Drugs
• Drugs t hat causes hyperkalemia (increases
t he pacemaker t hreshold) like sch which
also may inhibit a normally f unct ioning
cardiac pace maker by causing cont ract ion
of skelet al ms groups (myo pot ent ials)t hat
t he pulse generat or could int erpret as
int rinsic R wave.
• I f SCH t o be used def asiculat ing dose of
non depolarizing ms relaxant s should be
given prior t o t his.
• Et omidat e and ket amine should be avoided

122. Factors affecting CIED
FUNCTION
---Electro cautery/ MRI /Radio frequency ablation
Effect of MRI on pacemaker
• Inhibition of pacing
• Asynchronous pacing
• Inappropriate defibrillation /complete device
failure
• Shielding reduces problems now a days.

125. • If emergency defibrillation is needed ,keep the
defibrillator away( 12 cm) from the pulse
generator & lead system(antero-posterior
direction pads).

126. Post Operative Management
• Interrogating the device & restoring
baseline settings( like anti tachycardia
therapy).
• Cardiac rate ,rhythm monitoring
continuously, Hypothermia prevention.
• Reprogramming.

127. Pace maker failure
1. Failure to pace
2. Failure to capture
3. Undersensing / failure to sense
4. Oversensing
Pacemaker failure
BP stable
Hypotension
Asystole
Observe
O2
Atropine
Dopamine
Adrenaline
Isoprenaline
Temporary pacing
CPR
Pace maker failure

128. Thank you !