1. Advanced Pacemaker Operations Module 7
Student Notes
It is possible that you may require additional supplemental materials to enhance your knowledge or provide more practice. If you feel this is necessary for you, ask your instructor for suggestions on books or other tools.
Instructor Notes
This module should take approximately 2 hours to cover.
To deliver this module, the following materials are recommended:
Printed participant guides for each participant
Overhead projector and screen
Optional: Whiteboard or flip chart
While delivering the module engage, the learners by asking questions and getting them to talk based on their previous subject knowledge.
Evaluate the learners by delivering the knowledge check at the end of this module. An acceptable score is 80%.
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Toll-free: 1 (800)
Medtronic USA, Inc.
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UC d EN
Medtronic, Inc.
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January 2008

2. Objectives Define: Blanking and refractory
Complete VVI and DDD timing diagrams
Correctly identifying PVARP, PVAB, PPAB, and TARP
Identify events in refractory and blanking, and their effect on timing
Correctly identify Marker Channel™ notations
Identify upper rate behaviors
Calculate 2:1 vs. Wenckebach rates
Student Notes
Instructor Notes

3. Marker Channel™
Very useful in helping you understand how the IPG is interpreting events
Each manufacturer has its own code
Medtronic’s code:
AS  Atrial Sense
AP  Atrial Pace
AR  Atrial Refractory
VS  Ventricular Sense
VP  Ventricular Pace
VR  Ventricular Refractory
Student Notes
A note on Marker Channel diagnostics. These were first introduced by Medtronic and greatly simplify the interpretation of pacemaker behavior – as you will see when we come to the troubleshooting module!
The Marker Channel notations are available once the pacemaker is interrogated, and they are displayed on both the Programmer ECG screen and print outs. Caution – each pacemaker manufacturer has its own codes for events. Medtronic’s are displayed on this slide.
Note: The Marker Channel is the devices interpretation of events. If sensing is appropriate, the following Marker Channels correspond to the listed physiologic event:
AS = P-wave
VS = R-wave
Instructor Notes
There are other Medtronic Marker Channel notations that we’ll cover later.

4. What Do You Think Would Happen Next If…
The QRS was sensed by the atrial channel? AS AP VP
Note: The Marker Channel tells you how the pacemaker is interpreting these events.
DDD 60
Click for Answer
Student Notes
Instructor Notes
Ask: Suppose we had a dual chamber pacemaker, and it suddenly started sensing a QRS on the atrial channel. What effect might this have on pacemaker behavior? Would the pacemaker operate as planned?
The QRS is sensed on the atrial channel, and it is interpreted by the pacemaker as a P-wave. We call the phenomena Far-field R-wave sensing (FFRW), and the effect might inhibit the pacemaker and restart the underlying lower-rate timer. It will also trigger an AV delay, and ventricular pacing will occur faster than desired. Thus, the pacemaker would not be operating as intended.
The next atrial pace would be inhibited because the pacemaker thinks the QRS is a P-wave.
Obviously, this is not how we want a DDD pacemaker to behave. This was a problem in early pacemakers.

5. What Do You Think Would Happen Next If…
These T-waves were sensed by the ventricular channel?
Actual Rate: 50 bpm or 1200 ms VP VS VP VS
Programmed: VVI 60
Student Notes
The next ventricular pace would be inhibited because the pacemaker thinks the T-wave is an R-wave.
Obviously, this also is not how we want a pacemaker to behave.
Instructor Notes
Here is another, and perhaps more common example of a pacemaker problem – T-wave oversensing.
Ask: In this VVI pacemaker, what happens if a T-wave is sensed by the ventricular channel?
It is interpreted as a QRS and the pacemaker inhibits and restarts
Ask: Is this how we want it to behave?
No, it is not desirable
Click for Answer

6. Blanking and Refractory Periods
Blanking Period
A period of time during which the sense amplifiers are off, and the pacemaker is “blind”
Some blanking periods are programmable, some are non-programmable
Refractory Period
A period of time during which sensed events are ignored for timing purposes, but included in diagnostic counters
Some refractory periods are programmable, some non-programmable
Student Notes
Blanking and Refractory periods were introduced as a way to help manage what the pacemaker is sensing, and when it uses the information.
Blanking periods are somewhat analogous to the Absolute Refractory Period we studied in an earlier module. In the case of a pacemaker, during Blanking it is unable to SENSE. The sense amplifier is OFF.
During Refractory the pacemaker is able to sense, but it ignores the event for the purposes of timing. For example, a refractory event may be noted in a diagnostic counter, but it will not alter or effect timing.
Instructor Notes

7. Why Do We Use Refractory and Blanking Periods?
Pacemaker sensing occurs when a signal is large enough to cross the sensing threshold
Sensing does not tells us anything about the origin or morphology of the sensed event, only its “size.”
5.0 mV
2.5 mV
1.25 mV
Student Notes
As we discussed earlier, a pacemaker only notes an event when it crosses the programmable sensing threshold, but when that occurs, the pacemaker is still unable to determine anything more about that signal. Nothing about its morphology, its origin, is looked at. Nothing but that it exceeded the sensing threshold.
Instructor Notes
The second waveform on this slide is a T-wave.
Ask: Why do we need these periods in pacemakers?
Since nothing about the waveforms morphology or its origin is know by the pacemaker, timing must be utilized to classify the event as something other than an R-wave
1.25 mV Sensitivity
Time

8. Why Do We Use Refractory and Blanking Periods?
By manipulating the sense amplifiers, we filter signals based on their relationship
5.0 mV
The potential for digitizing these signals may someday allow pacemakers to discriminate signals based on morphology rather than just on their relationship.
2.5 mV
SENSE!
1.25 mV
Student Notes
However, by applying blanking and refractory periods, it allows us to make some discrimination about the signal based on its relationships with other signals around it.
In the example above, immediately upon sensing the signal, the amplifier goes into blanking – it goes “dark” for a programmable period of time. Then the amplifier restarts, but it is in refractory – the pacemaker ignores signals for a programmable period of time. In other words, during the refractory period, the pacemaker sees the signal, but it does not affect pacemaker timing.
Instructor Notes
Sensing
Blanking
Refractory
Time

9. Let’s Look at the VVI Example Again…
Now, is the T-wave sensed by the ventricular channel? VP VR
VVI 60
Click for Answer
Student Notes
Instructor Notes
For review:
Ask: What do the following markers represent?
VS—ventricular sense
VP—ventricular pace
VR—ventricular refractory
Ask: This is the same ECG previously seen. What is the new effect on this VVI ECG?
The T-waves fall in a refractory period and ignored for timeing purposes
The T-wave falls in the ventricular refractory period (VR), and it is ignored for timing purposes.
The VVI pacemaker is operating normally.

10. VVI Timing Note the addition of the Blanking and Refractory periodsVP VR
1000 ms
Blanking
Refractory
VRP 320 ms
Student Notes
Blanking and refractory periods occur in every timing cycle, and in both dual and single chamber pacemakers.
The purpose of the ventricular blanking period is to avoid sensing the ventricular pace.
The purpose of the ventricular refractory period is to avoid sensing T-waves.
Instructor Notes
The pacemaker applies these periods to every timing cycle.

11. T-wave Sensing
Is there another way to program the pacemaker to ignore the T-waves?
Click for Answer VP VR
1000 ms
VRP 320 ms
Blanking
Refractory
Student Notes
Instructor Notes
We could program the pacemaker to be less sensitive (e.g., from 2.5mV to 5.0 mV). But then it might not sense every R-wave.

12. Dual Chamber Timing Refractory and Blanking Periods
ARP
PVARP
VRP
PVAB
Those affecting the atrial channel are indicated above the ECG baseline.
Those affecting the ventricular channel are indicated below the ECG baseline.
Student Notes
When drawing out timing diagrams, usually periods and notations referring to the atrial channel are drawn above the ECG baseline. Those referring to the ventricle are below the line.
Instructor Notes
Red: Blanking
Orange: Refractory period

13. Dual Chamber Timing Atrial Refractory and Blanking Periods
Post Ventricular Atrial Blanking
Atrial Refractory and Blanking Periods
PVAB
Atrial Blanking
ARP
PVARP
VRP
Student Notes
The atrial blanking and refractory periods are shown for DDD timing. The following is information on the purpose of each period:
Atrial Blanking—prevents the pacemaker from being “self-inhibited” by the atrial pacing output
Atrial Refractory Period—ignores sensed events on the atrial channel during the AV delay, so they do not restart the AV interval
Post Ventricular Atrial Blanking—prevents Far-field R-wave sensing of the ventricular pacing output, and the R-wave, on the atrial channel
Post Ventricular Atrial Refractory Period—prevents the AV interval from restarting due to sensed events (Far-field R-waves or retrograde conduction)
Keep in mind that the periods time out simultaneously. Look at PVARP and PVAB. They both begin with a ventricular pace (or sensed QRS). The PVAB is programmed to expire before PVARP does.
The atrial blanking that is shown, occurs only if there is an atrial pacing output. Had a P-wave occurred (an atrial sense), the AV delay would have been an atrial refractory period only.
Instructor Notes
Post Ventricular Atrial Refractory Period
Atrial Refractory Period

14. Post Atrial Ventricular Blanking Ventricular Refractory Period
Dual Chamber Timing
Ventricular Refractory and Blanking Periods
PVAB
ARP
PVARP
Post Atrial Ventricular Blanking
VRP
Ventricular Refractory Period
Student Notes
The ventricular blanking and refractory periods are shown here in typical DDD timing. The following is information on the purpose of each period:
Post Atrial Ventricular Blanking—prevents the ventricle from sensing the atrial pacing output
Ventricular Blanking—prevents “self-inhibition” from the ventricular pacing output
Ventricular Refractory Period—prevents oversensing of T-waves
The PAVB occurs only with an atrial pace.
Instructor Notes
Ventricular Blanking

15. Dual Chamber Timing Atrial Pace (AP) - Ventricular Pace (VP) example
A-A interval
VRP
ARP
PVARP
PVAB
PAV
V-A interval
DDD 60
Student Notes
Here we show the timing for A-V sequential pacing in the DDD mode. We’ve added the lower rate intervals and AV delays. These apply to every pacemaker cycle.
Instructor Notes
The pacemaker applies these periods every timing cycle.

16. Dual Chamber Timing Lower Rate (A-A) Interval
A-A interval indicates the minimum rate the device will pace under normal circumstances (“escape interval,” “lower rate interval”)
In dual chamber pacemakers we subdivide this into the A-V interval (PAV or SAV) and the V-A interval
Normally, the device is designed to always use A-A timing – to maintain a steady atrial rate
A-A interval
PAV
V-A interval
Student Notes
The lower rate interval (escape, or A-A interval) determines the devices minimum rate.
Thus, a Lower Rate of 60 bpm is an escape (or an A-A) interval of 1000 ms. Unless otherwise inhibited, the pacemaker will deliver an atrial pace every second, and in DDD, this atrial pace will start a PAV.
Instructor Notes
VRP
ARP
PVARP
PVAB

17. Dual Chamber Timing Upper Tracking Rate (UTR)
The maximum rate the ventricles will be paced 1:1 in response to atrial sensed events
VRP
ARP
PVARP
PVAB
A-A interval
SAV
V-A interval
UTR
Student Notes
The upper tracking rate (UTR) determines the maximum rate the pacemaker will continue to time out the programmed SAV. In other words, with a UTR of 120 bpm, the pacemaker will track the atrium (i.e., provide a ventricular pace for every P-wave) as long as the A-A interval is longer than 500 ms.
Why 500 ms? Because 500 ms = 120 bpm.
Instructor Notes

18. 1:1 tracking of any atrial sense
Dual Chamber Timing
Tracking
1:1 tracking (atrial sense – ventricular pace) occurs at rates above the Lower Rate, but below the Upper Tracking Rate
1:1 tracking of any atrial sense
A-A interval
A-A interval
UTR
VRP
ARP
PVARP
PVAB
Student Notes
So let’s assume DDD (lower rate – UTR). The pacemaker is tracking 1:1 (providing a VP for every AS) as long as:
The A-A is < 1000 ms, and
The A-A is > 500 ms
Instructor Notes
The dotted lines on this slide indicate the interval in which 1:1 tracking can occur.

19. Dual Chamber Timing The pacemaker’s response to high atrial rates
To a pacemaker, an increase in atrial rate means that V-A intervals are getting shorter
A-A interval
VRP
ARP
PVARP
PVAB
UTR
A-A interval
V-A interval
SAV
V-A interval
SAV
UTR
VRP
ARP
PVARP
PVAB
Student Notes
The reason the pacemaker responds this way is because each pacemaker cycle is evaluated in relation to the one previous. The pacemaker is measuring the A-A interval. If it is less than 500 ms (with a UTR of 120 bpm), it then must respond differently by delaying the ventricular pace.
Instructor Notes
The pacemaker’s response to high atrial rates is called upper rate behavior. This is covered in the “Dual Chamber Timing: Upper Rate Behavior” section of this module.
In other words, the next atrial sense is getting closer to the previous ventricular event.

20. Dual Chamber Timing Upper Rate Behavior
Student Notes
Instructor Notes
This section discusses pacemaker Wenckebach and 2:1 block.
These two upper rate behaviors interact with each other, but it is important to understand them individually first. Therefore, this section introduces them as separate concepts.

21. Upper Rate Behavior Pacemaker Wenckebach
Caused by the atrial rate exceeding the Upper Tracking Rate
Student Notes
Pacemaker Wenckebach has the characteristics of Wenckebach—the pattern of the PR (AV) interval gradually extending, beat-to-beat, until an atrial event falls into the PVARP and cannot restart an AV interval. In effect, a ventricular beat is “dropped.”
Instructor Notes
Use the Marker Channel to point out the atrial rate, since the P-waves on the surface ECG are difficult to see.

22. Upper Rate Behavior Pacemaker Wenckebach
Prolongs the SAV until upper rate limit expires
Produces gradual change in tracking rate ratio
A-A interval
A-A interval
A-A interval
UTR
UTR
UTR A S A S A R A P
Student Notes
Pacemaker Wenckebach mechansim:
The atrial rate increased to above the Upper Tracking Rate
The SAV times out, but a ventricular pace at that time would violate the UTR
The effective AV delay is prolonged until the end of the UTR
The delayed ventriclar pace delays the start of PVARP
Eventually, the next P-wave falls into the refractory period
Ventricular tracking is lost for one beat
Instructor Notes
ARP
PVARP
ARP
PVARP
ARP
PVARP
SAV
SAV
PAV V P V P V P

23. Wenckebach Example Pacemaker patient on an exercise test
4:3 Wenckebach operation
Each AS (P-wave) is followed by an increasing SAV, and then the VP
Eventually an atrial beat is not tracked, and a ventricular beat is dropped
Student Notes
On this slide we have an example of pacemaker Wenckebach obtained while a patient is having a graded exercise (stress) test. Note the increasing AV intervals and the 4 AS:3 VP (4:3) pattern.
Instructor Notes
Ask: Why is the atrial beat not tracked?
The P-wave fell into the PVARP of the previous ventricular event
The next slide illustrates this answer.

24. Wenckebach Example
This P-wave fell in the PVARP of the previous cycle.
It is refractory (AR), so it is ignored for timing.
It cannot start an SAV, so it is not followed by a ventricular pace.
This is normal upper rate pacemaker behavior.
Student Notes
Here we took the ECG and are zooming in.
By changing the beat-to-beat relationship and the relative relationship of the previous cycle’s PVARP to the next AS, eventually an AS falls in a PVARP – it is an AR.
Instructor Notes
Ask: What does this mean to pacemaker timing?
A refractory event is ignored for purposes of timing, so the pacemaker will not use it to start an SAV. Without an AV interval, there can be no VP. Thus, a beat is “dropped.”

25. Upper Rate Behavior 2:1 Block Occurs when P-waves are faster than TARP
TARP = SAV + PVARP
ARP
PVARP
ARP
PVARP
ARP
TARP
TARP
TARP A S A R A S A R A S
SAV
SAV
SAV
Student Notes
The total time that the atrial chamber of the pacemaker is in refractory, is during the AV interval and the PVARP. The Total Atrial Refractory Period (TARP) is equal to the SAV interval plus the PVARP. The TARP is important to understand as it defines the highest rate that the pacemaker will track atrial events before 2:1 block occurs.
Instructor Notes
TARP is an interval, so it must be converted to beats per minute in order to compare it to an atrial rate.
Ask: Given an SAV of 200 ms, and a PVARP of 300 ms, what is TARP?
TARP = 500 ms
Ask: Given the same parameters, what pacemaker rhythm will result from an atrial rate of 130 bpm?
2:1 block
Explanation:
TARP of 500 ms converts to 120 bpm (60,000 / 500 ms = 120 bpm)
The atrial rate (130 bpm) is faster than TARP, resulting in 2:1 block V P V P V P

26. Upper Rate Behavior 2:1 Block
Caused by the atrial rate exceeding the Total Atrial Refractory Period (TARP)
Student Notes
Pacemaker 2:1 block is characterized by two sensed P-waves per paced QRS complex. This pattern develops because every other P-wave falls into PVARP.
Instructor Notes

27. Knowledge Check
Given the following pacemaker parameters, what rhythm will result from an atrial rate of 130 bpm?
UTR = 120 bpm
SAV = 150 ms
PVARP = 250 ms
Pacemaker Wenckebach
Given the same pacemaker parameters, what atrial rate would result in 2:1 block?
An atrial rate above 150 bpm
Click for Answer
Click for Answer
Student Notes
Instructor Notes
Use this knowledge check to make sure that the learners understand Wenckeback and 2:1 block as independent concepts. It is important to understand them independently because the next several slides show how the two concepts interact with one another.

28. Upper Rate Behavior UTR 1:1 Atrial Tracking Wenckebach 2:1 Block
Ventricular Rate LR No
Ventricular
Pacing
Student Notes
When the intrinsic atrial rate approaches (and exceeds) the programmed upper rate (assuming the TARP is less than the upper rate interval), pacemaker operations will change from 1:1 tracking operations, to blocking operations, which are designed to prevent tracking atrial arrhythmias, which are too fast, and will likely cause patients to become symptomatic. The jagged line represents Wenckebach operation, characterized by a lengthening of the A-V interval, which occurs as the atrial rate exceeds the upper rate limit. If the atrial rate continues to increase, 2:1 block will occur, which means that every other P-wave will fall into refractory and will not be sensed. The ventricular paced rate will typically be half the atrial rate.
Instructor Notes
This slide illustrates the relationship between pacemaker Wenckeback and 2:1 block.
This slide builds from left to right, indicating a rise in atrial rate. As the atrial rate increases, illustrate to the learners the three responses to an increase in atrial rate:
1:1 atrial tracking
Wenckeback
2:1 block LR
UTR
TARP
Atrial Rate
= Ventricular Pacing

29. Upper Rate Behavior UTR Ventricular Rate LR 1:1 Atrial TrackingNo
Ventricular
Pacing
1:1 Atrial
Tracking
Wenckebach
2:1 Block
Student Notes
If the upper tracking rate interval is longer than the TARP, the pacemaker will exhibit Wenckebach behavior for some period of time before it goes into a 2:1 block pattern as the atrial rate increases.
If the upper rate interval is shorter than the TARP, the pacemaker will exhibit 2:1 block behavior first and will never be able to achieve the upper tracking rate as the atrial rate increases.
Instructor Notes
This slide illustrates the relationship between pacemaker Wenckeback and 2:1 block.
When animated, this slide shows what happens when TARP is too long:
Lower atrial rates create a 2:1 block
Essentially eliminating the Wenckebach window at the UTR
Ask: Is achieving 2:1 block immediately at the UTR a desirable situation?
No, this situation is not as desirable as the situation in which there is a period of Wenckebach before 2:1 block. Patients can tolerate the gradual ventricular rate drop of Wenckebach better than the precipitous ventricular rate drop caused by 2:1 block. LR
UTR
TARP
= Ventricular Pacing
Atrial Rate

30. Achieving a Higher UTR without Block
Decrease SAV
Decrease PVARP
PVARP
ARP
SAV A S R
TARP
PVARP
ARP
SAV A S R
TARP
PVARP
ARP
SAV A S
TARP
Increased Tracking
SAV A S
PVARP
ARP
TARP
Increased Tracking
Student Notes
There are 2 choices available to avoid 2:1 block at too slow of an atrial rate:
Decrease the AV interval. However, this may result in more ventricular pacing, which may have consequences for the patient. Rate-Adaptive AV will do this automatically for us.
Decrease PVARP. Typically this is the choice we might be inclined to make.
In both cases, the effect is to increase the 1:1 tracking window and to allow for Wenckebach at the UTR.
Instructor Notes
This slide builds on mouse clicks to show how TARP is decreased by decreasing SAV and then PVARP. In each instance, this slide shows how doing so improves tracking.
SAV A S
SAV A S

31. Achieving a Higher UTR without Block
SAV and PVARP managed automatically
Programming Rate-Adaptive AV to “On”
This will automatically decrease the SAV/PAV as the atrial rate increases
Programming PVARP to “Auto”
This will automatically decrease the PVARP as the atrial rate increases
Student Notes
As we mentioned earlier, TARP is the Total Atrial Refractory Period. When we manipulate either, or both, the AV or PVARP, we are manipulating TARP.
Rate-Adaptive AV (RAAV) is one way to allow the pacemaker to decrease the AV delay automatically, in response to faster atrial rates.
Automatic PVARP, or Auto PVARP, alters PVARP in response to increasing atrial rates. This permits long PVARP at slow rates to protect against the effects of retrograde conduction, but also permits a shorter TARP at faster atrial rates, so high UTR can be achieved without worrying about 2:1 block.
Instructor Notes

32. If Long TARP is the Problem…
Why not just program short AV Intervals or short PVARP?
Short AV intervals may force ventricular pacing
Short PVARP may allow retrograde conduction to be sensed
Consider this ECG:
The retrograde P-waves occur outside of PVARP.
The pacemaker tracks the retrograde P-waves.
This is called a Pacemaker Mediated Tachycardia (PMT).
Student Notes
PMT is covered in more detail in “CorePace Module 8: Troubleshooting.”
Instructor Notes

33. Status Check Can you identify the following Marker Channel notations?
Click for Answer AS VR AR AP VP VS
An Atrial Sense (P-wave)
Ventricular Refractory
Atrial Refractory
Atrial Pace
Ventricular Pace
A Ventricular Sense (QRS or R-wave)
Student Notes
Instructor Notes

34. Status Check Can you complete this timing diagram? Click for Answer VP
VRP VP
V. Blanking
Lower Rate Interval
Student Notes
Instructor Notes

35. Status Check Complete this timing diagram Show:
Atrial Refractory during the AV Interval
PVARP with PVAB
VRP
Atrial Refractory during the AV Interval
PVARP with PVAB
VRP
Student Notes
Instructor Notes
Click for Answer

36. Status Check You are called to evaluate this rhythm strip
Obtained while the patient is having an exercise test
Clinician thinks it is loss of capture
Patient’s underlying rhythm is CHB
What is going on?
Student Notes
Instructor Notes
Ask: What is going on?
Pacemaker 2:1 block
2:1 block. P-waves
Click for Answer

37. Status Check What mode do you think this is?
Calculate the Atrial and Ventricular rates
Propose a programming solution to resolve this
430 ms
860 ms
Student Notes
Instructor Notes
Ask: What mode do you think this is?
DDD
Ask: What are the atrial and ventricular rates?
Atrial rate: 430 ms or 140 bpm
Ventricular rate: 860 ms or 70 bpm
Ask: What are some programming solutions?
Increase UTR to above 140 bpm, if not already, and if it is appropriate for the patient
Turn on Rate Adapted AV
Turn on Auto PVARP
DDD Mode. Atrial rate: 430 ms or 140 bpm, Ventricular rate: 860 ms or 70 bpm.
Increase the UTR and program RA-AV on, or Increase UTR and decrease PVARP.
Click for Answer

38. Status Check
Given the following parameters, what will occur first as the patient’s atrial rate increases? Wenckebach or 2:1 block?
Upper Tracking Rate: 120 bpm
SAV = 200 ms
PVARP = 350 ms
2:1 block will occur first
Click for Answer
Student Notes
Instructor Notes
Ask: Given the following parameters, what will occur first as the patient’s atrial rate increases? Wenckebach or 2:1 block?
- Upper Tracking Rate = 120 bpm
- SAV = 200 ms
- PVARP = 350 ms
2:1 block will occur first
Explanation:
TARP = SAV + PVARP
TARP = 200 ms ms
TARP = 550 ms
550 ms corresponds to a rate of 109 bpm
Since 2:1 block occurs at a slower rate than the programmed UTR (109 bpm < 120 bpm), 2:1 block will occur first

39. Brief Statements Indications
Implantable Pulse Generators (IPGs) are indicated for rate adaptive pacing in patients who ay benefit from increased pacing rates concurrent with increases in activity and increases in activity and/or minute ventilation. Pacemakers are also indicated for dual chamber and atrial tracking modes in patients who may benefit from maintenance of AV synchrony. Dual chamber modes are specifically indicated for treatment of conduction disorders that require restoration of both rate and AV synchrony, which include various degrees of AV block to maintain the atrial contribution to cardiac output and VVI intolerance (e.g. pacemaker syndrome) in the presence of persistent sinus rhythm.
Implantable cardioverter defibrillators (ICDs) are indicated for ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias.
Cardiac Resynchronization Therapy (CRT) ICDs are indicated for ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias and for the reduction of the symptoms of moderate to severe heart failure (NYHA Functional Class III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy and have a left ventricular ejection fraction less than or equal to 35% and a QRS duration of ≥130 ms.
CRT IPGs are indicated for the reduction of the symptoms of moderate to severe heart failure (NYHA Functional Class III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy, and have a left ventricular ejection fraction less than or equal to 35% and a QRS duration of ≥130 ms.
Contraindications
IPGs and CRT IPGs are contraindicated for dual chamber atrial pacing in patients with chronic refractory atrial tachyarrhythmias; asynchronous pacing in the presence (or likelihood) of competitive paced and intrinsic rhythms; unipolar pacing for patients with an implanted cardioverter defibrillator because it may cause unwanted delivery or inhibition of ICD therapy; and certain IPGs are contraindicated for use with epicardial leads and with abdominal implantation.
ICDs and CRT ICDs are contraindicated in patients whose ventricular tachyarrhythmias may have transient or reversible causes, patients with incessant VT or VF, and for patients who have a unipolar pacemaker. ICDs are also contraindicated for patients whose primary disorder is bradyarrhythmia.

40. Brief Statements (continued)
Warnings/Precautions
Changes in a patient’s disease and/or medications may alter the efficacy of the device’s programmed parameters. Patients should avoid sources of magnetic and electromagnetic radiation to avoid possible underdetection, inappropriate sensing and/or therapy delivery, tissue damage, induction of an arrhythmia, device electrical reset or device damage. Do not place transthoracic defibrillation paddles directly over the device. Additionally, for CRT ICDs and CRT IPGs, certain programming and device operations may not provide cardiac resynchronization. Also for CRT IPGs, Elective Replacement Indicator (ERI) results in the device switching to VVI pacing at 65 ppm. In this mode, patients may experience loss of cardiac resynchronization therapy and / or loss of AV synchrony. For this reason, the device should be replaced prior to ERI being set.
Potential complications
Potential complications include, but are not limited to, rejection phenomena, erosion through the skin, muscle or nerve stimulation, oversensing, failure to detect and/or terminate arrhythmia episodes, and surgical complications such as hematoma, infection, inflammation, and thrombosis. An additional complication for ICDs and CRT ICDs is the acceleration of ventricular tachycardia.
See the device manual for detailed information regarding the implant procedure, indications, contraindications, warnings, precautions, and potential complications/adverse events. For further information, please call Medtronic at and/or consult Medtronic’s website at
Caution: Federal law (USA) restricts these devices to sale by or on the order of a physician.

41. Brief Statement: Medtronic Leads
Indications
Medtronic leads are used as part of a cardiac rhythm disease management system. Leads are intended for pacing and sensing and/or defibrillation. Defibrillation leads have application for patients for whom implantable cardioverter defibrillation is indicated
Contraindications
Medtronic leads are contraindicated for the following:
ventricular use in patients with tricuspid valvular disease or a tricuspid mechanical heart valve.
patients for whom a single dose of 1.0 mg of dexamethasone sodium phosphate or dexamethasone acetate may be contraindicated. (includes all leads which contain these steroids)
Epicardial leads should not be used on patients with a heavily infracted or fibrotic myocardium.
The SelectSecure Model 3830 Lead is also contraindicated for the following:
patients for whom a single dose of 40.µg of beclomethasone dipropionate may be contraindicated.
patients with obstructed or inadequate vasculature for intravenous catheterization.

42. Brief Statement: Medtronic Leads (continued)
Warnings/Precautions
People with metal implants such as pacemakers, implantable cardioverter defibrillators (ICDs), and accompanying leads should not receive diathermy treatment. The interaction between the implant and diathermy can cause tissue damage, fibrillation, or damage to the device components, which could result in serious injury, loss of therapy, or the need to reprogram or replace the device.
For the SelectSecure Model 3830 lead, total patient exposure to beclomethasone 17,21-dipropionate should be considered when implanting multiple leads. No drug interactions with inhaled beclomethasone 17,21-dipropionate have been described. Drug interactions of beclomethasone 17,21-dipropionate with the Model 3830 lead have not been studied.
Potential Complications
Potential complications include, but are not limited to, valve damage, fibrillation and other arrhythmias, thrombosis, thrombotic and air embolism, cardiac perforation, heart wall rupture, cardiac tamponade, muscle or nerve stimulation, pericardial rub, infection, myocardial irritability, and pneumothorax. Other potential complications related to the lead may include lead dislodgement, lead conductor fracture, insulation failure, threshold elevation or exit block.
See specific device manual for detailed information regarding the implant procedure, indications, contraindications, warnings, precautions, and potential complications/adverse events. For further information, please call Medtronic at and/or consult Medtronic’s website at
Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.

43. Disclosure
NOTE:
This presentation is provided for general educational purposes only and should not be considered the exclusive source for this type of information. At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in a particular situation.