Increase atrial and ventricular mA 6. AAI: normal atrial pacing 7. VVI: normal ventricular pacing 8. DDD: failure to sense atria; increase atrial sensitivity 9. DDD: failure to capture ventricle; increase ventricular mA

1. Temporary Pacemakers
Dr. Rajab Ali
Assistant Professor-PCICU
1

2. Temporary pacemakers
Objectives
– Defination
– Explain the situations when temporary
pacemakers are indicated.
– Describe the principles of pacing.
– Illustrate normal and abnormal pacemaker
behavior.
– Discuss the steps to be taken in troubleshooting
a temporary pacemaker.
2

3. Definition
• Cardiac Pacemaker: is a medical device that
generates electrical impulses delivered by electrodes
to cause the heart muscle chambers to contract and
therefore pump blood.
• T-Triggered: The pacemaker will pace in response to
sensed event.
• I-Inhibited: The pacemaker will not pace if it senses
an intrinsic event.
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4. Indications for Temporary Pacing
• Bradyarrhythmias
• AV conduction block
– Congenital complete heart block (CHB)
• L-Transposition (corrected transposition)
• Surgical/ cardiac interventions
• Trauma
• Slow sinus or junctional rhythm
• Permanent pacer malfunction
• Drugs, electrolyte imbalances
• Sick Sinus Syndrome
– Secondary to pronounced atrial stretch
– Old TGA s/p Senning or Mustard procedure
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5. Method of Temporary Pacing
• Temporary pacing types
– Epicardial
– Transvenous
– Transcutaneous
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6. Epicardial Pacing
• The most common method of temporary pacing
in cardiac ICU via postoperative epicardial wires
• A pair of Wires sutured to right atrium & right
ventricle epicardium.
• Atrial wires exit on the right of the sternum
• Ventricular wires exit on the left of the
sternum.
• One wire from each pair serves as a cathode
and an othere as a anode, allowing bipolar
sensing and pacing of either or both chambers.
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7. 7

8. Temporary Epicardial
Pacemakers
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9. Transvenous Pacing
• Emergency use with external pacemaker
• Require central access and carries risk of
Bacteremia/infection.
• Appropriate placement should be guided by
fluoroscopy or echocardiography.
• Confirmation of position by plain film of
chest.
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10. Transvenous Pacing
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11. Transcutaneous Pacing
• Emergency use with external pacemaker
• Significant sedation is often required
due to the discomfort caused by this
method of pacing.
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12. Transcutaneous Pacing
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13. Pulse generator :
- Power source
- Electric circuitry
Lead
wire(s)
Basic Components of Pacemaker System
IPG
EPG
13

14. • Contains a battery that
provides the energy for
sending electrical
impulses to the heart
• Houses the circuitry that
controls pacemaker
operations
Circuitry
Battery
The Pulse Generator:
14

15. • Leads Are Insulated
Wires That:
• Deliver electrical
impulses from the
pulse generator to
the heart
• Sense cardiac
depolarization
Lead
Pacemaker Leads
15

16. Principles of Pacing
Wiring systems
• Unipolar
– One electrode on the heart (-)
– Signals return through body fluid
and tissue to the pacemaker (+)
• Bipolar
– Two electrodes on the heart (- & +)
– Signals return to the ring electrode
(+) above the lead (-) tip.
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17. Single-Chamber Pacing System
• The pacing lead is
implanted in the
atrium or ventricle,
depending on the
chamber to be paced
and sensed
17

18. Paced Rhythm Recognition
AAI / 60
18

19. Paced Rhythm Recognition
VVI / 60
19

20. • Dual-Chamber
Systems Have Two
Leads
• One lead implanted
in the atrium
• One lead implanted
in the ventricle
Dual-Chamber Pacing System
20

21. Paced Rhythm Recognition
DDD / 60 / 120
21

22. Paced Rhythm Recognition
DDD / 60 / 120
22

23. Paced Rhythm Recognition
DDD / 60 / 120
23

24. Paced Rhythm Recognition
DDD / 60 / 120
24

25. • Stimulate cardiac depolarization
• Sense intrinsic cardiac function
• Respond to increased metabolic demand
by providing rate responsive pacing
• Provide diagnostic information stored by
the pacemaker
Most Pacemakers Perform Four Functions:
25

26. Principles of Pacing
Modes of Pacing
 Atrial pacing
 Intact AV conduction system required
 Ventricular pacing
 Loss of atrial kick
 Discordant ventricular contractions
 Sustains cardiac output
 Atrial/Ventricular pacing
 Natural pacing
 Atrial-ventricular synchrony
26

27. 27

28. IN temporary pacemaker only the first three
letters of the code are used.
The fourth letter in common use to denote
presence or absence of rate responsiveness in
permanent pacemaker.
The fifth letter of code in not commonly used
except in cardiac resynchronization therapy
(CRT) devices.
28

29. Principles of Pacing
3-letter NBG Pacemaker Code
First letter: Chamber Paced
V- Ventricle
A- Atrium
D- Dual (A & V)
O- None
29

30. Principles of Pacing
3-letter NBG Pacemaker Code
Second letter: Chamber Sensed
V- Ventricle
A- Atrium
D- Dual (A & V)
O- None
30

31. Principles of Pacing
3-letter NBG Pacemaker Code
Third letter: Sensed Response
T- Triggers Pacing
I- Inhibits Pacing
D- Dual (trigger and inhibition)
O- None
31

32. Principles of Pacing
• Commonly used modes:
– AAI - atrial demand pacing
– VVI - ventricular demand pacing
– DDD – atrial/ventricular demand pacing,
senses & paces both chambers; trigger or
inhibit
32

33. Example of Pacemaker
 Medtronic 5388
Dual Chamber
(DDD)
33

34. Pacemaker Code
34

35. Pacemaker EKG Strips
• Assessing Paced EKG Strips
– Identify intrinsic rhythm and clinical condition
– Identify pacer spikes
– Identify activity following pacer spikes
– Failure to capture
– Failure to sense
• EVERY PACER SPIKE SHOULD HAVE A P-WAVE
OR QRS COMPLEX FOLLOWING IT.
35

36. Normal Pacing
 Atrial Pacing
 Atrial pacing spikes followed by P waves
36

37. Normal Pacing
• Ventricular pacing
– Ventricular pacing spikes followed by wide,
bizarre QRS complexes
37

38. Normal Pacing
• A-V Pacing
– Atrial & Ventricular pacing spikes followed by
atrial & ventricular complexes
38

39. Normal Pacing
• DDD mode of pacing
– Ventricle paced at atrial rate
39

40. Failure to capture:
• The pacemaker send
stimulus that is not
followed by
corresponding P or
QRS wave.
• You fixe it by adjusting
(Pacing) output and its
related connections
Failure to sense:
• The pacemaker did not
see the P or QRS wave
and send stimulus in
spite of that
• You fix it by adjusting
input (sensing
sensitivity) and its
related connections.
40
2 problem related to Pacemaker
functioning should be identified

41. 41

42. Abnormal Pacing
• Atrial non-capture
– Atrial pacing spikes are not followed by P waves
42
No P wave

43. Abnormal Pacing
• Ventricular non-capture
– Ventricular pacing spikes are not followed by
QRS complexes
43
No QRS complex

44. Failure to Capture:
the pacing stimulus was not followed by P or
QRS wave (no chamber contraction)
• Causes
– Insufficient energy delivered by pacer
– Low pacemaker battery
– Dislodged, loose, fibrotic, or fractured electrode
– Electrolyte abnormalities
• Acidosis
• Hypoxemia
• Hypokalemia
• Danger - poor cardiac output
44

45. • Solutions
– View rhythm in different leads
– Change electrodes
– Check connections
– Increase pacer output (↑mA)
– Change battery, cables, pacer
45
Failure to Capture

46. • Atrial under-sensing (failure to sense normal P wave)
– Atrial pacing spikes occur regardless of P waves
– Pacemaker is not “seeing” intrinsic activity
46
Abnormal Pacing: what is the problem?
There should be
no atrial pacing
after P wave

47. • Ventricular under-sensing (failure to sense normal QRS wave)
– Ventricular pacing spikes occur regardless of QRS
complexes
– Pacemaker is not “seeing” intrinsic activity
47
Abnormal Pacing: what is the problem?

48. A basic principle
• The pacemaker works with this principle : If I see or receive (sense) stimulus (P/QRS) I
do not fire (Pace) , If I do not sense stimulus (P/QRS) I will fire (Pace). What makes the
pacemaker sees the intrinsic rhythm is pacemaker sensitivity (higher sensitivity
means less ability to see/hear intrinsic rhythm and that will result in more pacemaker
firing ). Less sensitivity means more ability to see intrinsic rhythm and less pacemaker
firing.
• Under-sensing means the pacemaker does not see intrinsic rhythm (P or QRS) so the
pacemaker will fire which will cause pacemaker impulse delivered in wrong time
(may lead to life threatening arrhythmia) or higher rate than needed due to frequent
pacing that is not needed
• The management of under-sensing by increasing pacemaker sensitivity (decrease
filtering so pacemaker sees and hears intrinsic rhythm) so the pacemaker does not
fire more than it should or fire during wrong timing.
• Over sensing, the pacemaker sees too many artifacts and interpret them as normal P
or QRS leading to not delivering the impulse where it should be delivered (that will
result in slow inadequate rhythm or low cardiac output)
• The management of over-sensing is decrease sensitivity (increase filtering ability so
pacemaker sees and hears less surrounding artifacts) so pace maker fire more
appropriately.
48

49. • Definition: Minimum level of intrinsic
electric activity generated by the heart
detectable by the pacemaker
4/07 49
Sensitivity Threshold

50. How to set sensitivity and output
50
Sensing
Threshold
The safe level
to set sensitivity
< 50%

51. Sensitivity – The Greater the Number, the Less
Sensitive the Device to Intra-cardiac Events

52. 
Amplitude
(mV)
Time
5.0
2.5
1.25
Sensitivity

53. 
Amplitude
(mV)
Time
5.0
2.5
1.25
Sensitivity (under-sensing)
Management: you need to increase sensitivity

54. 
Amplitude
(mV)
Time
5.0
2.5
1.25
Sensitivity (over-sensing)
Management: you need to increase sensitivity

55. 55
20%
Sensitivity Threshold Testing

56. Failure to Sense:
The heart own rhythm P or QRS /chamber
contraction was not recognized by pacemaker
• Causes
– Pacemaker not sensitive enough to patient’s
intrinsic electrical activity (mV)
– Insufficient myocardial voltage
– Dislodged, loose, fibrotic, or fractured
electrode
– Electrolyte abnormalities
– Low battery
– Malfunction of pacemaker or bridging cable
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57. • Abnormal Rate: Faster Rhythm than what is targeted
• Abnormal Timing of Rhythm : Danger – potential
(low) for paced ventricular beat to land on T wave
57
Failure to sense can lead to abnormal
Pacing: what is the problem? Failure to sense
R on T
Normal QRS

58. • Solution
– View rhythm in different leads
– Change electrodes
– Check connections
– Increase pacemaker’s sensitivity (↓mV)
– Change cables, battery, pacemaker
– Reverse polarity
– Check electrolytes
– Unipolar pacing with subcutaneous “ground wire”
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Failure to sense

59. Over-sensing
• Pacemaker inhibited due to sensing of “P” waves &
“QRS” complexes that do not exist
• Pacing does not occur when intrinsic rhythm is
inadequate
59

60. • Causes
– Pacemaker inhibited due to sensing of “P”
waves & “QRS” complexes that do not exist
– Pacemaker too sensitive
– Possible wire fracture, loose contact
– Pacemaker failure
• Danger - heart block, asystole
60
Over-sensing

61. • Solution
– View rhythm in different leads
– Change electrodes
– Check connections
– Decrease pacemaker sensitivity (↑mV)
– Change cables, battery, pacemaker
– Reverse polarity
– Check electrolytes
– Unipolar pacing with subcutaneous “ground wire”
61
Over-sensing

62. Advantages: Requires only a single lead. Simple. Has
the advantage of maintaining AV synchrony
Disadvantages: Slow ventricular rates may develop if
AV block occurs.
Clinical use: sinus node dysfunction without AV node
dysfunction.
Commonly Encountered Pacing Mode: AAI

63. Advantages: Requires only a single lead. Simple.
Probably most commonly used mode
Disadvantages: During pacing AV synchrony is not
preserved ( Asynchrony between atrium and ventricle)
Clinical uses: AV block. mode of choice in life
threatening brady-arrhythmias
Commonly Encountered Pacing Mode: VVI

64. Advantages:AV synchrony is maintained for
patients with sinus node and AV node disease
Disadvantages: Require two leads. More
complex
Clinical uses: Bradycardia caused by SND or
AV node disease
Commonly Encountered Pacing Mode: DDD

65. Advantages: AV synchrony is maintained during
atrial pacing. Useful in patients with SA node
dysfunction and episodes of atrial tachyarrhythmias.
During atrial tachyarrhythmias pacemaker paces
ventricle at back-up rate and will not track
tachyarrhythmia
Disadvantages: AV synchrony is not maintained
during atrial sensing
Clinical uses: For patients with bradycardia and
intermittent atrial tachycardia
Commonly Encountered Pacing Mode: DDI

66. Practice Strip#1:
Question what type of pacing do you see?
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67. Practice Strip #2: if you are told that patient is
connected to pacemaker with back up rate of 80
which mode could he have: ??
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68. Practice Strip #3
Patient on DDD mode what is the problem?
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QRS

69. Practice Strip #4
What type of pacing does the patient have?
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70. Practice Strip #5
Patient is on DDD mode, what is the problem?
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71. Practice Strip #6
What type of pacing is used in this patient?
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72. Practice Strip #7
What type of pacing?
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73. Practice Strip #8
Patient on DDD mode , what is the problem?
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74. Practice Strip #9
Patient on DDD mode, what is the problem?
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75. Answers
Mode of pacing, rhythm/problem, solution
1. AAI: normal atrial pacing
2. Sinus rhythm: no pacing; possible back-up setting AAI, VVI, DDD
3. DDD: failure to sense ventricle; increase ventricular mA
4. VVI: ventricular pacing
5. DDD: failure to capture atria or ventricle; increase atrial & ventricular
mA
6. DDD: normal atrial & ventricular pacing
7. DDD: normal atrial sensing, ventricular pacing
8. DDD: failure to capture atria; increase atrial mA
9. DDD: oversensing; decrease ventricular sensitivity
75