1. ECG in Pacemaker Malfunction
Sriram Rajagopal,
Southern Railway Hospital,
Perambur,Chennai

2. ECG in “Pacemaker Malfunction” (ECGs in Pacemaker Function Assessment)
Sriram Rajagopal,
Southern Railway Hospital,
Perambur,Chennai

3. Implantable Pacemaker Systems Contain the Following Components:
Lead wire(s)
Implantable pulse generator (IPG)
A basic pacing system is made up of:
Implantable pulse generator that contains:
A power source—the battery within the pulse generator that generates the impulse
Circuitry—controls pacemaker operations
Leads—Insulated wires that deliver electrical impulses from the pulse generator to the heart. Leads also transmit electrical signals from the heart to the pulse generator.
Electrode—a conductor located at the end of the lead; delivers the impulse to the heart.

4. Pseudomalfunctions Pseudomalfunctions are defined as:
CorePace Module 4: Troubleshooting
Pseudomalfunctions
Pseudomalfunctions are defined as:
Unusual
Unexpected
Eccentric
ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function
Pseudomalfunctions should be ruled out as the cause(s) of an anomalous ECG strip before corrective measures are taken.

5. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

6. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

7. ECGs in Patients with Pacemakers
What do pacemakers do ?
Pace
Sense – ( what ? )
Respond – Inhibit , Trigger or Dual
Respond to increased metabolic demand by providing rate responsive pacing
Provide diagnostic information stored by the pacemaker

8. Timing Intervals Are Expressed in Milliseconds
One millisecond = 1 / 1,000 of a second
Part of understanding timing intervals requires an acquaintance with milliseconds. Many Healthcare professionals are accustomed to measuring intervals in seconds. Timing intervals in pacing, however, are always measured in milliseconds. The exception to this is lower and upper rates, which are usually expressed in beats per minute/bpm.
The graphic above shows intervals in milliseconds of a normal sinus beat. The entire graph represents 1000 milliseconds or one second of time.
The smallest box on the ECG represents 40 milliseconds or .04 seconds. The medium box represents 200 milliseconds or .2 seconds.

9. Rate Conversion Conversion Pacing rate in PPM divided by 60,000 = ms
60,000 / 60 PPM = 1000 ms
Interval in ms divided by 60,000 = PPM
60,000 / 1000 ms = 60 PPM
60,000 ms
BPM

10. Paced Rhythm Recognition
VVI / 60

11. Paced Rhythm Recognition
VVI / 60

12. Paced Rhythm Recognition
AAI / 60

13. Noncapture is Exhibited By:
CorePace Module 4: Troubleshooting
Noncapture is Exhibited By:
No evidence of depolarization after pacing artifact
This ECG strip shows loss of atrial capture, followed by a scheduled ventricular pace. Following the ventricular pulse, the marker channel recorded an intrinsic P-wave.
Loss of capture

14. CorePace Module 4: Troubleshooting
No Output
Pacemaker artifacts do not appear on the ECG; rate is less than the lower rate
When the pacemaker problem is no output, the marker channel shows pacing markers—AP or VP—although no artifact appears on the ECG.
No output is defined as the failure to pace. Impulses are generated from the IPG, but is not transferred to the lead.
Pacing output delivered; no evidence of pacing spike is seen

15. Fusion Beat
Definition: The combination of an intrinsic beat and a paced beat.
The morphology varies; in other words, a fusion beat doesn’t really look like a paced beat or an intrinsic beat.
The pacemaker and the patient contribute to depolarization in Fusion beats.

16. Fusion
Ventricular Fusion

17. Pseudofusion Beat
Definition: A pacing pulse falls on an intrinsic beat. The pacing pulse is ineffective and the intrinsic complex is not altered.
The pacemaker does NOT contribute to depolarization in Pseudofusion beats.

18. Pseudofusion
Ventricular Pseudofusion

19. Dual-Chamber Systems Have Two Leads:
One lead implanted in the atrium
One lead implanted in the ventricle

20. Paced Rhythm Recognition
The notation at the top refers to mode, lower rate, and upper rate parameters. This mode of operation can be described as atrial synchronous pacing or atrial tracking.
DDD / 60 / 120

21. Paced Rhythm Recognition
DDD / 60 / 120

22. Paced Rhythm Recognition
Pacing in the atrium and ventricle is often described as AV sequential pacing.
DDD / 60 / 120

23. Paced Rhythm Recognition
DDD / 60 / 120

24. Sensing
Sensing is the ability of the pacemaker to “see” when a natural (intrinsic) depolarization is occurring
Pacemakers sense cardiac depolarization by measuring changes in electrical potential of myocardial cells between the anode and cathode

25. Sensitivity – The Greater the Number, the Less Sensitive the Device to Intracardiac Events
Pacemakers have programmable sensitivity settings that can be thought of like a fence: with a lower fence more of the signal is seen; with a higher fence less of the signal is seen.

26. Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time
If the system is sensing myopotentials, then raise the fence or increase the number of the sensitivity setting. The pacemaker will "see less" of the incoming signal.
If the pacing system is not “seeing” intrinsic cardiac events, set the fence lower or decrease the number of the sensitivity setting. The pacemaker will then "see” more of the incoming signal.
Time

27. Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time
In this example, the sensitivity number is set higher than the signal. The pacemaker is unable to see any activity and undersensing will result.
Time

28. Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time
In this example, the sensitivity setting is set such that the pacemaker will likely sense the T wave. Oversensing will occur.
Time

29. Scheduled pace delivered Intrinsic beat not sensed
Undersensing . . .
Pacemaker does not “see” the intrinsic beat, and therefore does not respond appropriately
Scheduled pace delivered
Intrinsic beat not sensed
VVI / 60

30. Oversensing
VVI / 60
...though no activity is present
Marker channel shows intrinsic activity...
An electrical signal other than the intended P or R wave is detected
Oversensing will exhibit pauses in single chamber systems. In dual chamber systems, atrial oversensing may cause fast ventricular pacing without P waves preceding the paced ventricular events.

31. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

32. ECGs in Patients with Pacemakers
Basic Data :
Clinical details – age , indication for pacing, time since implant etc
Type of pacemaker
Programmed parameters
Magnet Behaviour
Special features

33. CorePace Module 4: Troubleshooting
Magnet Operation
Magnet application causes asynchronous pacing at a designated “magnet” rate
Magnet operation varies within different product lines and from manufacturer to manufacturer, but will usually involve a rate change when the magnet is applied. The Threshold Margin Test (TMT) is part magnet operation for most of Medtronic’s devices. The following operation describes magnet operation and TMT for most Medtronic devices:
Three beats at 100 bpm, followed by a magnet rate of 85
The third beat has an automatic pulse width decrement of 25% (loss of capture would indicate that the stimulation safety margin is inadequate)
Dual chamber devices will shorten the AV delay to 100 ms
Elective replacement indicators will change the rate from 85 to 65 and the mode from dual to single chamber pacing
It is important to remember that magnet modes vary from manufacturer to manufacturer, and from device to device. While recent Medtronic devices use the above rule of thumb, many older devices used the programmed lower rate as the magnet rate, or would decrease the rate by a certain percentage as a battery depletion indicator.
Kappa devices have a feature called Extended TMT. Extended TMT is a programmable feature and will operate as follows: TMT is performed at 100 ppm with the pulse width reduced by 25% on the third pulse, 50% on the fifth pulse, and 75% on the seventh pulse. This type of operation is extremely useful in assessing adequate safety margins, by simply using a magnet.

34. Rate Responsive Pacing
CorePace Module 4: Troubleshooting
Rate Responsive Pacing
An accelerating or decelerating rate may be perceived as anomalous pacemaker behavior
If a patient is active it is easy to equate rate increases with rate responsive pacing. Some patients may experience “false positive” increases in rate from their sensors. In the case of a piezoelectric crystal, the pacemaker may begin pacing at a faster rate if, for example, the patient is either lying on the side that the pacemaker is implanted on or experiencing a bumpy car ride.
Minute ventilation sensors measure the change in respiration rate and tidal volume. If a patient experiences rapid respiration resulting from a cause other than exercise (e.g., hyperventilation), the pacemaker may begin pacing at a faster rate.
VVIR / 60 / 120

35. CorePace Module 4: Troubleshooting
Hysteresis
Allows a lower rate between sensed events to occur; paced rate is higher
Hysteresis Rate 50 ppm
Lower Rate 70 ppm
Hysteresis provides the capability to maintain the patient’s intrinsic heart rhythm as long as possible, while providing back-up pacing if the intrinsic rhythm falls below the hysteresis rate. Because hysteresis exhibits longer intervals between sensed events, it may be perceived as oversensing.

36. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

37. ECGs in Patients with Pacemakers
Single chamber pacing :
Identify underlying intrinsic rhythm if any ( in each chamber)
Verify appropriate sensing ( if possible )
Verify capture
Measure base rate and check if appropriate
Identify any variations in intervals and interpret
Identify causes of inappropriate sensing or pacing

38. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

39. Single Chamber ECG Analysis
Programmed Parameters
Mode………………………………………….. VVI
Base Rate……………………………………… ppm
Magnet Response…………………….. Battery Test
Hysteresis Rate………………………………… Off ppm
T Temporary programmed value
1.0 Second
7 Mar :20 1

40. ECG #1
VVI
Normal Capture and Sensing 1

41. Single Chamber ECG Analysis
Programmed Parameters
Mode………………………………………….. VVI
Base Rate……………………………………… ppm
Magnet Response…………………….. Battery Test
Hysteresis Rate………………………………… Off ppm
T Temporary programmed value
1.0 Second
Jun :57 pm 2

42. ECG #2
VVI
Normal Sensing
Capture unknown 2

43. Single Chamber ECG Analysis3

44. ECG #3
VVI
Normal Capture and Sensing with initiation of Hysteresis 3

45. Single Chamber ECG Analysis4

46. ECG #4 VVI Loss of Ventricular Sensing
Ventricular Undersensing with Functional loss of capture on the second to last beat 4

47. Single Chamber ECG Analysis5

48. ECG #5 VVI Loss of Ventricular capture with functional loss of sensing

49. Single Chamber ECG Analysis6

50. ECG #6
VVI
Normal Capture
Ventricular Oversensing 6

51. Single Chamber ECG Analysis10

52. Single Chamber ECG Analysis10

53. ECG #10 VVI Capture Unknown Normal Sensing
Normal initiation of Hysteresis 10

54. Single Chamber ECG Analysis12

55. Single Chamber ECG Analysis12

56. ECG #12
VVI
Normal Capture
Ventricular Undersensing 12

57. Single Chamber ECG Analysis13

58. Single Chamber ECG Analysis13

59. ECG #13
VVI
Loss of Ventricular Capture
Normal Sensing 13

60. Single Chamber ECG Analysis15

61. ECG #15
VVIR
Normal Capture and Sensing under Sensor drive 15

62. Crosstalk

63. ECGs in Patients with Pacemakers
Overview :
Basic principles of pacing
Background information required
Systematic approach
Examples with single chamber pacing
Examples with dual chamber pacing

64. A Systematic Approach Measure Base Rate
Measure AV/PV (PAV/ SAV) Interval
Verify Atrial capture
Verify Atrial sensing
Verify Ventricular capture
Verify Ventricular sensing
Verify Underlying rhythm
Document

65. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AVD 200 ms
PVARP 250 ms
ECG # 3

66. Answer ECG #3 Loss of Atrial Capture Normal Atrial Sensing
Base Rate 60 ppm
MTR 120 ppm
AVD 200 ms
PVARP 250 ms
Loss of Atrial Capture
Normal Atrial Sensing
Normal Ventricular Capture
Ventricular Sensing Unknown

67. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 150 ms
PVARP 250 ms
ECG # 5

68. Answer ECG #5 Normal Atrial Capture Atrial Sensing Unknown
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 150 ms
PVARP 250 ms
Normal Atrial Capture
Possible Psuedofusion on 4th atrial output
Atrial Sensing Unknown
Loss of Ventricular Capture
Normal Ventricular Sensing
Functional Loss of Ventricular Sensing

69. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
ECG # 10

70. Answer ECG #10
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
Normal Atrial Capture with one beat showing functional loss of atrial capture
Atrial Undersensing
Normal Ventricular Capture
Ventricular Sensing Unknown

71. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
ECG # 12

72. Answer ECG #12 Normal Atrial Capture Normal Atrial Sensing
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
Normal Atrial Capture
Normal Atrial Sensing
Normal Ventricular Capture with two beats of functional loss of capture
Ventricular Undersensing

73. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
ECG # 20

74. Answer ECG #20 Initiation of 2:1 block upper rate response
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 200 ms
PVARP 250 ms
Initiation of 2:1 block upper rate response
Normal Upper Rate Behavior Operation

75. Dual Chamber ECG Analysis
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 150 ms
Min. PV ms
PVARP 250 ms
ECG # 24

76. Answer ECG #24 Normal Atrial Capture Normal Atrial Sensing
Base Rate 60 ppm
MTR 120 ppm
AV 200 ms
PV 150 ms
Min. PV ms
PVARP 250 ms
Normal Atrial Capture
Normal Atrial Sensing
Normal Ventricular Capture
Ventricular Sensing Unknown
Initiation of a Pacemaker Mediated Tachycardia (PMT) with following a PVC

77. ECGs in Patients with Pacemakers
Conclusions :
Familiarity with basics of pacemaker function
Knowledge of clinical background and details of pacing system
Programmed parameters – essential
Familiarity with special features
Systematic approach

78. Thank you for your kind attention !

79. ECGs in Patients with Pacemakers

80. ECGs in Patients with Pacemakers

81. ECGs in Patients with Pacemakers

82. ECGs in Patients with Pacemakers

83. ECGs in Patients with Pacemakers

84. ECGs in Patients with Pacemakers

85. ECGs in Patients with Pacemakers

86. ECGs in Patients with Pacemakers

87. ECGs in Patients with Pacemakers