1. Pacemaker : overview Chennai: Feb2017
Title slide for this presentation.
This presentation is an up-to-date overview of cardiac pacing for physicians and clinical staff referring patients for pacemaker therapy.
For more about this presentation, see the companion binder Guidelines for Presenting Programs to Referring Physicians. This binder has guidelines and additional resources for presenting programs about cardiac pacing.
Chennai: Feb2017

2. The Implantable Pacemaker System
The Implantable Pulse Generator (IPG) : metal can (titanium) containing electronics/battery & an electrode or lead connector header
Lead : Electrical connection between the pacemaker & the heart

3. Unipolar & Bipolar Pacing
Anode (+)
Anode (+)
Cathode (-)
Cathode (-)

4. Indifferent electrode
A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In This System, the Impulse:
Flows through the tip electrode located at the end of the lead wire
Stimulates the heart
Returns to the ring electrode above the lead tip
Anode
Cathode
The impulse:
Travels down the lead wire to stimulate the heart at the tip electrode, which is the cathode (–)
Travels to the ring electrode, which is the anode (+), located several inches above the lead tip
Returns to the pulse generator by way of the lead wire
Tip electrode coil
Indifferent electrode
coil

5. Pacemaker Functions Stimulation of Cardiac Tissue
Sensing of natural (intrinsic) cardiac depolarization or contraction
Diagnostic information

6. Voltage, Current, and Impedance Are Interdependent
Voltage represents the force with which . . .
Current (water) is delivered through . . .
A hose, or lead, where each component represents the total impedance:
The nozzle, representing the electrode
The tubing, representing the lead wire
Speakers Notes
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What to Do:
What to Ask:
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Speakers Notes
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Ohm’s Law
Voltage = Current X Resistance (V=IR)
Current = Voltage/Resistance
As voltage increases, current increases
As resistance decreases, current increases

7. Pulse Duration (Width)
The Pacing Pulse t
V = Pulse Amplitude in Volts (V) (say 2.5 V)
t = Pulse Duration or Width in milliseconds (ms)
(say 0.5 ms)
R = Impedance of Pacing Circuit (ohms)
(say 500 ohms)
I = V/R = Current through pacing circuit (mA)
= 2.5 V/ 500 ohms = A = 5 mA
Pacing Pulse V
Output Voltage t
Pulse Duration (Width)

8. Stimulation Threshold
Pacing Voltage Threshold – The minimum pacing voltage at any given pulse width required to consistently stimulate the heart causing it to contract

9. Capture – Loss of Capture
Speakers Notes
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Capture
Non-Capture
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VVI / 60

10. NBG Code for Pacing P: Simple programmable V: Ventricle V: Ventricle
Chamber
Paced II
Sensed
III
Response
to Sensing IV
Programmable
Functions/Rate
Modulation V
Antitachy
Function(s)
P: Simple
programmable
V: Ventricle
V: Ventricle
T: Triggered
P: Pace
M: Multi-
programmable
A: Atrium
A: Atrium
I: Inhibited
S: Shock
D: Dual (A+V)
D: Dual (A+V)
D: Dual (T+I)
C: Communicating
D: Dual (P+S)
O: None
O: None
O: None
R: Rate modulating
O: None
S: Single
(A or V)
S: Single
(A or V)
O: None

11. Single Chamber Pacemakers
Most basic type of pacemaker
Works only on one chamber
of the heart – usually the RV
Paces the heart at a FIXED RATE
programmed
Inhibits pacing whenever a natural heartbeat is sensed by the pacemaker

12. Single Chamber Pacemakers
Ventricular Single Chamber Pacing or VVI pacing
Pacing Rate
Pacing Rate
Pace
Sense
Pace

13. Single-Chamber System
AAI
VVI
Speakers Notes
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14. Dual Chamber Pacemakers
DDD, DDDR – sense & pace both atrium and ventricle
VDD – Sense atrium, pace ventricle

15. The four faces of dual chamber pacing
AV SEQUENTIAL PACING Atrial Pacing Rate – 60, AV Interval – 200 ms
AV Synchronous Pacing :NATURAL ATRIAL CONTRACTION & VENTRICULAR PACING : VDD
AV Interval = 150 ms
Spontaneous Atrial Rate – 55
Spontaneous Atrial Rate – 110

16. The four faces of dual chamber pacing
Atrial Pacing Rate = 70, Natural AV conduction
NATURAL ATRIAL CONTRACTION WITH NORMAL AV CONDUCTION
Spontanoeus Atrial Rate = 65, Spontaneous PR interval = 160 ms

17. 72 M with symptomatic bifasicular block with prolonged PR interval #1
72 M with symptomatic bifasicular block with prolonged PR interval
s/p DDD pacemaker 2 week ago, UTR 100/min
Returns with history of atypical R sided chest pain and back pain
SBP 70 mm Hg BP improved promptly with IV fluid and pt felt better

18. Typical values LRL : 50-60/mt URL : 110-130/mt AV delay : 120-200/ms
PVARP : 250 ms
VRP : 200 ms
Blanking periods : < 50 ms

19. Sensing of intrinsic heartbeats
Sensing is the ability of the pacemaker to “see” when a natural (intrinsic) depolarization is occurring
Pacemakers record the Intracardiac Electrogram (EGM) by constantly recording the potential difference between the cathode and anode
Depolarization Wave
Processed by Device

20. Scheduled pace delivered Optional Information:
Undersensing
Pacemaker does not “see” the intrinsic beat, and therefore does not respond appropriately
Scheduled pace delivered
Speakers Notes
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Intrinsic beat
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VVI / 60

21. 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
Pacing is inhibited
Speakers Notes
What to say:
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.
What to Do:
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22. Amplitude Threshold Testing
Keeping pulse width stable, decrement voltage until loss of capture
@ 0.5ms
1.5V
1.0V
.5V

23. Intrinsic R wave Amplitude
Typical intrinsic R wave amplitude measured from pacing leads in the Right Ventricle are more than 5 mV in amplitude
Intrinsic R wave in EGM
Amplitude
The Intrinsic R wave amplitude is usually much greater than the T wave amplitude

24. Sensitivity Setting
This is a value specified to the pacemaker in millivolts through programming.
All ventricular electrogram deflections seen by the pacing lead that exceed the sensitivity setting will be identified by the pacemaker as intrinsic R waves
The typical sensitivity setting that is programmed for Ventricular sensing is 2.5 mV

25. Sensitivity Setting
5.0
5.0
2.5
2.5
Amplitude (mV)
Amplitude (mV)
1.25
1.25
Time
Time
Sensitivity settings less than 2.5 mv – High sensitivity – can lead to oversensing
Sensitivity settings greater than 2.5 mV – Low sensitivity – can lead to undersensing

26. { VVI Mode Pacing inhibited with intrinsic activity
Lower Rate Interval
In inhibited modes (VVI/AAI), intrinsic events that occur before the lower rate interval expires will reset the lower rate interval, as shown in the example above. As with paced events, sensed events will also initiate blanking and refractory periods. VP VS VP
Blanking/Refractory
VVI / 60

27. VVI TIMING V VP VP VP VS VP

28. VVI TIMING V VP VP VP VS VP

29. VVI TIMING V VP VP VP VS VP

30. VVI TIMING V VP VP VP VS VP

31. VVI TIMING V VP VP VP VS VP

32. VVI TIMING V VP VP VP VS VP

33. VVI TIMING V VP VP VP VS VP

34. VVI TIMING V VP VP VP VP

35. VVI TIMING V VP VP VP VS VP

36. VVI TIMING V VP VP VP VS VP

37. VVI TIMING V VP VP VP VS VP

38. Sensed native R waves reset VVI timing
65/mt
VVI
VVI
VVI
VVI
Fusion beat
Sensed native R waves reset VVI timing

39. Observation, Data, and Events Program
Presenting Rhythm and Rate
Battery Status
Lead Status
Sensing
Threshold
Observation, Data, and Events
Program
During this workshop we will cover the steps outlined by the PBL STOP acronym. These steps are discussed in detail in subsequent slides.

40. Diagnostic Information
With Medtronic ICDs and IPGs, important observations and diagnostic information is highlighted on the main Quick Look™ (initial interrogation) screen.
The screen on the left is from an EnPulse pacemaker. The screen on the right is from an EnTrust ICD.

41. Cardiac Compass® Management of atrial tachyarrhythmias
May help with assessment of:
Rate-control therapy
Rhythm-control therapy
Risk for stroke1
This Cardiac Compass report is from a Medtronic EnPulse pacemaker.
1Glotzer TV, Hellkamp AS, Zimmerman J. et al., Atrial high rate episodes detected by pacemaker diagnostics predict death and stroke: Report of the Atrial Diagnostics Ancillary Study of the Mode Selection Trial (MOST). Circulation 2003;107:

42. Potential Problems with Pacemakers
Battery Depletion
Lead displacement or perforation
Loss of capture and/or sensing
Lead fracture or insulation break
Increase in thresholds due to
Drugs
Electrolyte imbalance
Interference from external electromagnetic sources
Device malfunction

43. Pacemaker Follow-up All the Information for Routine Follow-ups
Operating Mode
Last Interrogation
Longevity
A&V Pacing Thresholds
Arrhtymia Summary
% Pace/Sense Histograms
All of the information provided by the Quick Look II screen is also made available (automatically) in printed format via the Initial Interrogation Report.
When Observations suggest that further investigation is warranted and/or troubleshooting is required, access to more detailed information can be found through the use of the QuickLink™ [>>] icon or via the Main Icons listed on the right-hand side of the display.
To potentially assist clinicians with assessing rhythm-control and/or rate-control therapies used during management of atrial tachyarrhythmias, the Adapta Pacing System offers two observations:
Number of days with > 4 hours of AT/AF.
Notification if number 1 above is satisfied AND the ventricular response (rate) during those AT/AF episodes exceeded 100 bpm at least 5% of the time.
Note: IF Rule #1 triggers (at least 1 day with > 4 hours AT/AF), then this is displayed instead of # of A. High Rate Episodes in Observations.
A&V Pacing Lead Impedance
Alert of situations that may require further investigation
P&R wave Amplitudes

44. Magnet Operation Varies across manufacturers and models
Medtronic Normal
VOO, DOO mode 85 ppm
No sensing, asynchronous pacing
Medtronic ERI – VOO, DOO mode 65 ppm

45. Special Precautions – EMI
General Principle
Avoid proximity to powerful electric or magnetic fields
Move away from the field if symptomatic
Keep safe distance – 6 inches for electrical appliances
Safe from Interference
Microwave, TV, Washing Machine, Fridge, Vacum cleaners etc.
Cordless phones
Computer, printer, scanner, photcopier
Possible interference
Items with large magnets, e.g. speakers, car ignition systems
Hand-held hair dryers
Radiotransmitters
Cellular Phones