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MDT Algorhythms Flashcards

1
Q

What is the purpose of the Ventricular Safety Period (VSP)?

A

prevents cross talk or the inhibition of ventricular pacing d/t the sensing of an atrial event

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2
Q

How does the Ventricular Safety Pacing (VSP) algorithm prevent crosstalk?

A
  • prevents cross talk by sensing for a “ventricular event” within a 110ms window following an atrial sensed event
  • any “VS” in window will be ignored and VP will occur after 110ms
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3
Q

What is the Ventricular Safety Pacing window length?

A

110ms

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4
Q

Ventricular Safety Period (VSP) is available when device is operating in what modes?

A
  • DDDR
  • DDD
  • DDIR
  • DDI
  • DVIR
  • DVI
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5
Q

Sensing Assurance helps ensure the appropriate detection of which rhythm(s)?

A
  • Atrial Fibrillation
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6
Q

What does the Auto-Adjusting Sensitivity algorithm do?

A
  • in Ventricular channel, allows for programming low sensitivity levels (0.3mV) that will sense fine, variable VF signals while auto-adjusting to prevent T-wave sensing
  • in atrial channel, ensures proper P-wave and AF sensing
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7
Q

What does Atrial Capture Management (ACM) do?

A
  • automatically monitors atrial pacing thresholds at periodic intervals and determines output based on programmable safety margin and minimum amplitude
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8
Q

What does the Lead Monitor feature do?

A

measures the impedance of the connected lead(s)

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9
Q

What does Implant Detect do?

A

ensures that pacing and sensing polarities are set appropriately at the time of implant

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10
Q

What does the Sleep Function do?

A

suspends the programmed lower rate and replaces it with a sleep rate

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11
Q

What does the Single Chambr/Rate Hysteresis algorithm do?

A
  • promotes intrinsic activity below the programmed lower rate
  • prevents device from pacing/overriding slow but appropriate intrinsic rhythms (inactivity/sleep)
  • only for single chamber modes with RR off
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12
Q

How does the Auto-Adjusting Sensitivity algorithm work?

A
  • automatically decreases sensitivity beat-beat to the smaller of the following:
    • 10x programmed value
    • 75% of P-R interval
  • then sensitivity decays, gradually returning to programmed value
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13
Q

What does ACR stand for in relation to Atrial Capture Management?

A

Atrial Chamber Reset Method

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14
Q

What does AVC stand for in relation to Atrial Capture Management?

A

AV Conduction Method

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15
Q

What does Ventricular Capture Management (RA/RVCM) do?

A

automatically monitors ventricular pacing thresholds at periodic intervals and determines output based on programmable safety margin and minimum amplitude

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16
Q

What are the 2 Atrial Capture Management (ACM) methods to pacing thresholds?

A
  • Atrial Chamber Rest Method (ACR)
  • AV Conduction Method (AVR)
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17
Q

Which method is used to calculate pacing thresholds if ACM senses 8 consecutive VS events and stable 1:1 AV conduction?

A
  • AV Conduction Method - overdrives atria by 15 bpm but no faster than 101 bpm
  • no R-wave = loss of capture
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18
Q

When will ACM use the AV Conduction method to calculate the pacing thresholds?

A

if ACM senses 8 consecutive VS events and stable 1:1 AV conduction

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19
Q

When will ACM use the Atrial Chamber Reset method to calculate the pacing thresholds?

A

if ACM senses 8 consecutive AS events and a HR < 87bpm

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20
Q

How often does Atrial Capture Management check threshold measurements?

A

QD at 0100 or 1 am

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21
Q

How often does Atrial Capture Management check threshold measurements?

A

QD at 0100 or 1 am

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22
Q

Which algorithm measures lead impedances?

A

lead monitor

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23
Q

How does RV Capture Management (RVCM) work?

A
  • paces RV and decrements output until loss of capture
  • 3 support cycles -> test pace -> back up pace will occur after 90ms at programmed amplitude and pulse width of 1.0
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24
Q

How does Implant Detection work?

A

auto-polarity configuration delivers 3 asynchronous pulses at 85 bpm, 5 min after lead connection and again after 30 mins if first test is a failure

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25
Q

What happens if device fails Implant Detections 5 min post lead connection bipolar test?

A
  • polarity is permanently set to unipolar
  • if lead is bipolar, another test will be performed after 30 minutes
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26
Q

What features are suspended until the Implant Detection algorithm/feature is turned off?

A
  • rate response
  • managed ventricular pacing (MVP)
  • sensing assurance
  • capture management (CM)
  • diagnostic date collection
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27
Q

What happens if the device fails the Implant Detection polarity test done 5 mins after implant?

A

device is set to unipolar and another test is done after 30 mins

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28
Q

How does the sleep function work?

A

at a set bed time, the lower rate is reduced/changed to programmed sleep rate

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29
Q

Is the sleep function nominally on or off?

A

it is off, needs to be turned on and programmed

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30
Q

How does the Single Chamber/Rate Hysteresis algorithm work?

A
  • lower rate is temporarily suspended and the Hysteresis rate becomes the new escape rate
  • pacing is inhibited as long as the intrinsic beat stays above the hysteresis rate
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31
Q

What does the Managed Ventricular Pacing (MVP) algorithm do?

A
  • promotes intrinsic conduction by reducing unnecessary RV pacing
  • provides atrial based pacing with ventricular backup
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32
Q

What is considered persistent AV conduction loss by the Managed Ventricular Pacing (MVP) feature and what will the device do?

A
  • 2 of 4 most recent beats show loss of ventricular conduction
  • device switches to DDDR or DDD mode
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33
Q

MVP mode is an appropriate therapy for which type of patient?

A

pts with SND and good AV conduction

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34
Q

What is the goal of the Search AV+ algorithm?

A

Promotes intrinsic ventricular activity by reducing unnecessary RV pacing

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35
Q

How does Search AV+ work?

A
  • adjusts SAV/PAV intervals based on AV conduction time of 8/16 VS events to promote intrinsic activation of the ventricles
  • if 8 of 16 are paced, too long or too short program takes action.
  • AV conduction divided into 3 zones, then adjustments are made (time, too short, too long)
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36
Q

What are the zones used by the Search AV+ algorithm to determine how to adjust the SAV/PAV interval?

A
  • time
  • too short: ≥8 VS events occurred within > 55ms of scheduled VP
  • too long: ≥8 VS events occurred 15ms before scheduled VP or were paced events
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37
Q

What does the PM do if the Search AV+ algorithm determines that AV conduction is too long?

A

Lengthens the SAV and PAV intervals by 62ms to promote intrinsic conduction

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38
Q

What does the PM do if the Search AV+ algorithm determines that AV conduction is too short?

A

Shortens the SAV and PAV intervals by 8ms to promote intrinsic conduction

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39
Q

What is the purpose of the Mode Switch feature?

A

to prevent rapid ventricular pacing r/t the tracking of paroxysmal atrial tachyarrhythmias

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40
Q

What does the Mode Switch feature do?

A
  • switches to atrial non-tracking mode (DDIR or VDIR) when an atrial tachyarrhythmia is detected then switches back when episode ceases
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41
Q

What are the Mode Switch detection criteria for low power devices (Adapta, Versa, Sensia)?

A
  • if 4 of 7 consecutive A-A are faster then the mode switch rate
  • atrial rate is ≥ detection rate and duration criteria is satisfied
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42
Q

What is the Blanked flutter search feature in relation to the Mode Switch and how does it work?

A
  • monitors for 2:1 blanking of Atrial events
  • q90 secs, checks for 8 consecutive A-A intervals < TAB x 2 and an
    atrial rate > 1/2 the mode switch detect rate
  • extends PVARP to 300ms to uncover blanked AS events
  • will mode switch if 2 A events are seen (AR-AS-VP or AR-AS-VS)
  • if no AS is uncovered, an AP will occur 30ms after the 2nd AS was expected to happen
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43
Q

What are/is the criteria needed for the Mode Switch feature to return to atrial tracking mode?

A
  • 7 consecutive A-A intervals longer than UTR
    or
  • 5 consecutive AP occurs
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44
Q

Mode Switch and MVP modes adjust pacing according to what criteria?

A
  • pts atrial rhythm and AV conduction status
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45
Q

When should the feature Mode Switch be turned on?

A
  • is nominally on after leads are connected
  • important if pt has a hx of, or is suspected to have atrial arrhythmias
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46
Q

Which feature adapts the pacing rate to changes in the pts physical activity?

A

Rate Response

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47
Q

How does Auto PVARP protect against pacemaker mediated tachycardia (PMT)?

A
  • lengthens PVARP when HR is low and shortens PVARP as HR increases to maintain 1:1 tracking
  • allows 1:1 atrial tracking up to 30 bpm above the HR or up to 100 bpm, whichever is greater
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48
Q

In Advisa PM, ICD and CRT devices, Automatic PVARP makes adjustments based on what?

A
  • pts current HR as measured by the RR median interval
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49
Q

In Adapta, Versa, and Sensia PMs, Automatic PVARP makes adjustments based on what?

A
  • the mean atrial rate (MAR)
  • avg of all A-A intervals except thos starting with an AS or AR sense and ending with an AP
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50
Q

What is the purpose of the Auto PVARP feature?

A
  • to protect against pacemaker mediated tachycardia (PMT)
  • helps keep 2:1 block rate above the UTR
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51
Q

What does the Rate Adaptive AV (RAAV) feature do?

A
  • mimics normal physiologic response of shortening AV conduction times w/ increase HR and lengthening w/ decrease in HR
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52
Q

What is the purpose of the Rate Adaptive AV (RAAV) feature?

A

helps keep 2:1 block rate above UTR

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53
Q

How does the Rate Adaptive AV (RAAV) feature help keep the 2:1 block rate above the UTR?

A
  • shortens the AV interval for atrial rates within the programmed Start/Stop rate
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54
Q

What does the “Start Rate” determine in r/t the RAAV?

A

rate at which shortening of the SAV and PAV intervals begin

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55
Q

What does the “Stop Rate” determine in r/t the RAAV?

A

rate at which the shortest SAV and PAV interval occur

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56
Q

How does shortening the SAV interval increase atrial sensing?

A
  • shortening the total refractory period (TARP) and increasing the 2:1 block rate
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57
Q

How does shortening the PAV interval increase atrial sensing?

A
  • lengthen the atrial sensing window of the VA interval at higher sensor driven rates
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58
Q

What are the criteria for PMT?

A
  • 8 consecutive VA intervals < 400ms in duration
  • start with VP event
  • end with AS event
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59
Q

How does Pacemaker Mediated Tachycardia Intervention treat PMT?

A
  • increases PVARP to 400ms for one cycle after the 9th VP event
  • next atrial event should be an atrial refractory (AR) event
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60
Q

What is the cause of PMT?

A

the sensing and tracking of retrograde P-waves d/t loss of AV synchrony causing ventricular pacing at the UTR

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61
Q

Are atrial refractory events tracked by the ventricle?

A
  • no
  • atrial events falling with the PVARP do no start SAV timer, therefore are not tracked by the ventricles
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62
Q

How does the device confirm PMT prior to lengthening the PVARP by the PMT intervention feature?

A
  • device temporarily extends the SAV interval by 50ms for 1 beat and evals changes in the VP-AS interval
  • performed 3x if necessary
  • if VP-AS intervals remains consistent = PMT
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63
Q

Once PMT intervention occurs, the feature is automatically suspended for how long?

A

85-90 secs (based on device)

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64
Q

What is the purpose of PVC Response?

A

to prevent PMT

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65
Q

How does PVC Response prevent PMT?

A
  • extends PVARP 400ms after sensing a PVC
  • Atrial events falls within PVARP = not tracked
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66
Q

What is the purpose of Non-Competitive Atrial Pacing (NCAP) feature?

A
  • to prevent the triggering of atrial tachycardias
  • prevent “competitive pacing”
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67
Q

How does the Non-Competitive Atrial Pacing (NCAP) feature prevent atrial tachycardias?

A
  • stops delivery of AP during atrial refractory period
  • sense AR event starts 300ms NCAP period, device will not AP in this window
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68
Q

What are TDI/FDI?

A
  • programmable zones that identify VF and VT
  • Tachy detect interval
  • Fibrillation detect interval
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69
Q

What type of counter is used to detect VF?

A
  • probabilistic counter
  • 30/40 beats = 30 of last 40 beats must be VF for detection to occur
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70
Q

What type of counter is used to detect VT?

A
  • consecutive counter
  • a VS will reset counter to zero
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71
Q

When does the device us a combined count when analyzing a rhythm?

A

when tachyarrhythmias jump between the Vf and VT detection zones

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72
Q

When does the device detect VF using the combined count method?

A

if any of the last 8 invervals are in the VF zone (FS)

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73
Q

When does the device detect Vt using the combined count method?

A

if 8 of 8 last intervals are in VT zone

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74
Q

What are the types of Ventricular ATP?

A
  • burst
  • ramp
  • ramp+
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75
Q

ATP is used to treat?

A

VT and FVT, arrhythmias with single reentry circuit

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76
Q

Cardioversion (RV) is used to treat?

A

VT and FVT

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77
Q

What is the most important step to perform prior to cardioversion?

A

synchronize and deliver shock on the R-wave

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78
Q

What does the defibrillation feature do?

A

simultaneously depolarizes the heart tissue to restore NSR

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79
Q

Defibrillation is used to treat?

A

VF episodes

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80
Q

How do you program VSP in pacemakers?

A
  • is nominally on
  • params -> additional features
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81
Q

How do you program VSP in ICD?

A
  • is nominally on
  • pacing -> params -> additional features
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82
Q

In what modes are sensitivity adjustments by the Sensing Assurance feature allowed?

A
  • allowed in VDD and MVP(R)
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83
Q

In what modes are sensitivity adjustments by the Sensing Assurance feature not allowed?

A
  • not allowed in AAT/VVT modes
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84
Q

How do you turn Sensing Assurance on?

A
  • is nominally on
  • params -> atrial/ventricular sensitivity
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85
Q

What are the steps taken by the Sensing Assurance feature when adjusting sensitivity values?

A

1) calculates “Target Sensing Margin” based on the sensitivity setting, type of lead and its polarity
2) P- and R-wave compared to target margin and classified as low, adequate or high amplitude
3) adjust sensitivity
- if 17 consecutive beats are “Low”, sensitivity is adjusted to the next programmable value that is more sensitive
- if 36 consecutive beats are “High”, sensitivity is adjusted to the next programmable value that is less sensitive

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86
Q

When would the Sensing Assurance feature adjust the sensitivity to the next programmable value that is more sensitive (decrease sensitivity value)?

A
  • if 17 consecutive beats (P- or R- wave) are classified as “Low”
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87
Q

When would the Sensing Assurance feature adjust the sensitivity to the next programmable value that is less sensitive (increase sensitivity value)?

A
  • if 36 consecutive beats (P- and/or R-waves) are classified as “High”
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88
Q

Auto-adjusting Sensitivity is used to ensure detection of what rhythm(s)?

A
  • fine, variable V-Fib
  • A-Fib
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89
Q

How is Ventricular CM turned on in pacemakers?

A
  • automatically turned on after Implant Detection is complete
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90
Q

How is Ventricular CM turned on in ICDs’/CRT-Ds?

A

1) params
2) pacing
3) RV amplitude
4) capture management

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91
Q

Capture Management will not program ventricular outputs above what value?

A
  • 5.0V or 1.0ms
  • will need to be programmed manually
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92
Q

What are 3 programming options that promote intrinsic ventricular activaion?

A
  • program long AV delay (SAV/PAV)
  • turn on Search AV+
  • turn on MVP
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93
Q

What are the programming options to manage/prevent Cross-Talk?

A
  • reduce atrial output
  • increase vent sensing value (make less sensitive)
  • program to bipolar if possible
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94
Q

How does the Managed Ventricular Pacing feature know when to mode switch back to AAI-AAIR?

A
  • performs periodic checks, will switch back to AAIR or AAI mode if AV conduction has resumed
  • starts after 1 min, then doubles up to 16 hrs, then checks every 16hrs
  • ex: 1min, 2min, 4min, 8min ->16hrs, 16hrs….
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95
Q

What is considered transient AV conduction loss by the Managed Ventricular Pacing (MVP) feature and what will the device do?

A
  • if AV conduction is lost in 1 of last 4 beats
  • device remains in AAI(R) and gives a backup VP 80ms after the next scheduled AP of non-conducted beat
  • VS events within the 80ms window will not inhibit VP which will fall in the refractory period
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96
Q

What is the criteria for the Search AV+ feature to consider an AV interval to short?

A
  • 8/16 VS events occurred within >55ms of scheduled VP
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97
Q

What is the criteria for the Search AV+ feature to consider an AV interval to long?

A
  • 8/16 VS events occurred 15ms before scheduled VP or were paced events
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98
Q

What is the Search AV+ features response to an AV interval that is too short?

A

shortens the SAV and PAV by 8ms for 16 beats

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99
Q

What is the Search AV+ features response to an AV interval that is too long?

A

lengthens the SAV and PAV by 62ms for 16 beats

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100
Q

What is the Wenchebach safety margin to use when programming the 2:1 block rate (TARP)?

A

program 2:1 block rate 30bpms higher than the upper tracking rate

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101
Q

Why should the 2:1 block rate be programmed to 30bpms higher than the upper tracking rate

A

to provide a Wenchebach safety window

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102
Q

What is the next step if the programmed minimum PVARP value is reached and 2:1 block rate is still lower than the UTR?

A

shorten the SAV interval increase the 2:1 block rate

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103
Q

Which pts should have Auto-PVARP turned on?

A

pts with chronotropic incompetence, chronic or paroxysmal AF

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104
Q

How does the device calculate the mean atrial rate?

A

looks at a rolling window of 4 beats

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105
Q

How does the NCAP feature prevent R-R intervals that are to long following their 300ms window?

A

feature shortens the SAV following each NCAP window

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106
Q

What is the minimum value that the NCAP feature will shorten the SAV interval?

A

30ms

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107
Q

What is the safety margin to use when programming the VT zone?

A

add 40ms to the pts known VT cycle length

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108
Q

What do for the following refer to regarding vectors:
1) HVA
2) HVB
3) HVX

A

1) can
2) RV coil
3) extra, usually the SVC coil

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109
Q

What does TF with a dot next to the F (TF∙) mean when seen in the marker channel?

A
  • FVT via VF is programmed
  • beat falls in FVT via VF zone
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110
Q

What does TF with a vertical line next to the F mean when seen in the marker channel?

A
  • last 8 beats are in the FVT via VF zone
  • FVT is detected
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111
Q

What does TF with a vertical line next to the F mean when seen in the marker channel?

A
  • one of last 8 intervals is FVT
  • FVT detected
112
Q

What does TF with a dot next to the T (T∙F) mean when seen in the marker channel?

A
  • FVT via VT is programmed
  • beat falls in FVT via VT zone
113
Q

What is the purpose of the Wavelet feature?

A

to prevent the inappropriate detection and tx of ventricular arrhythmias

114
Q

How does the Wavelet feature work?

A
  • creates template of the pts intrinsic rhythm to use a comparison when suspected ventricular arrhythmias occur
115
Q

When does the wavelet feature consider withhold detection and tx?

A
  • when 3/8 of the last QRS waveforms meet the match threshold percentage
  • nominally 70%
116
Q

Is the wavelet feature nominally on/off?

A

On

117
Q

Does the wavelet feature work at initial detection (NID), redetection (RNID) or both?

A

only at initial detection

118
Q

What is the purpose of the PR Logic feature?

A

to differentiate between SVT and true VT/VF and to withhold inappropriate VT/VF therapies

119
Q

Does the PR Logic feature work at initial detection (NID), redetection (RNID) or both?

A

only at initial detection

120
Q

Is PR Logic nominally on/off?

A

On with SVT V. Limit at 260ms

121
Q

Does the RV Lead Noise Discrimination algorithm work at initial detection (NID), redetection (RNID) or both?

A

both; detect and redetect

122
Q

Does the T-Wave Discrimination algorithm work at initial detection (NID), redetection (RNID) or both?

A

both; detect and redetect

123
Q

The Onset feature applies to which zones?

A

VT and FVT via VT zones only

124
Q

When is the Onset algorithm applied when analyzing a rhythm?

A

applied at pre-counting

125
Q

What is the purpose of the Stability feature?

A

to increase VT detection specificity

126
Q

The Stability feature is applied in which zone(s)?

A

VT zone only at detection and redetection

127
Q

Which feature avoids long sinus pauses by pacing at a programmed minimum interval after a PAC, then slowly reduces the rate?

A

Atrial Rate Stabilization

128
Q

Which feature avoids long sinus pauses by pacing at a programmed minimum interval after a PVC, then slowly reduces the rate?

A

Ventricular Rate Stabilization

129
Q

What is the purpose of the Post Mode Switch Overdrive Pacing (PMOP) feature?

A
  • to prevent early recurrence of AF (ERAF)
130
Q

Which feature is meant to prevent early recurrence of AF (ERAF?)

A

Post Mode Switch Overdrive Pacing (PMOP)

131
Q

How does the Post Mode Switch Overdrive Pacing (PMOP) feature work?

A
  • extends Mode Switch to DDIR mode after termination of an AT/AF episode
  • gradually increases pacing rate to programmed overdrive rate
  • after period ends, the rate gradually lowers to the sensor or LR and mode switches to previously programmed dual chamber mode
132
Q

What is/are the criteria for mode switch to occur in high power devices?

A
  • uses AT/AF evidence counter method, looks for # of A events within V-V interval
  • counter gets to 3 AND median of last 12 A-A are shorter then switch rate = reaching onset = mode switch
  • nominal mode switch A-A interval = 350ms or appx 175 bpm
133
Q

What is the nominal switch interval for Mode Switch feature?

A

350ms or appx 175bpm

134
Q

How do you know that Mode Switch occurred when interrogating a device?

A

when reviewing episodes, “MS” will be seen in the channel marker

135
Q

What are the Mode Switch detection criteria for Advisa DR MRI™, Revo MRI™, EnRhythm™, Consulta™ CRT-P, Syncra™ CRT-P and Medtronic ICDs?

A
  • uses AT/AF counter
  • atrial rate > AT/AF detection interval and there are more atrial events than ventricular events in 3 V-V intervals
136
Q

What is the purpose of Atrial Preference Pacing?

A
  • to maximize atrial percentage to reduce the incidences of atrial arrhythmias
  • to suppress atrial ectopic beats that may lead to atrial arrhythmias by atrial pacing at rate slightly higher than sinus rate
137
Q

Up to how long will cardiac compass store data?

A

up to 14 months

138
Q

What is an electrical storm as it relates to a PM or ICD?

A

when the patient experiences 3 or more appropriate VT therapies in a 24hr period

139
Q

What is the term for when the patient experiences 3 or more appropriate VT therapies in a 24hr period?

A

electrical storm

140
Q

Which feature measures intrathoracic impedance changes over time?

A

OptiVol

141
Q

When does OptiVol begin collecting data?

A

34 days after implantation to allow for pocket maturation

142
Q

What is the nominal OptiVol threshold?

A

60

143
Q

How does the OptiVol feature collect data?

A

sends impulse from the RVcoil to the can at 20min intervals bewtween 1200-1700

144
Q

How do you turn on OptiVol?

A

is automatically turned on 34 days after implant

145
Q

What is the name for the programmable value that is the maximum duration PR Logic can withhold VT/VF detection and therapies?

A

high-rate timeout

146
Q

When does PR Logic determine if far-field R waves are present?

A
  • if 2 atrial events occur in an R-R interval
  • algorithm will then analyze P-R or R-P patterns
  • is a FFRW if
    • R-P or P-R intervals are consistent
    • device detects an A-A interval that exhibits a short-long pattern, AND either an AV interval < 60ms or a VA (R-P) interval < 160ms
  • if 4/12 are FFRW then all are
147
Q

Which feature suppresses atrial ectopic beats that may lead to atrial arrhythmias by pacing at rate slightly higher than sinus rate?

A

Atrial Preference Pacing

148
Q

How does the RV lead noise discrimination algorithm prevent delivery of therapy d/t noise?

A
  • VS event triggers feature to examine far field signals to see if depolarization actually occurred
  • no depolarization = noise
  • looks at 12 beats, if 3/12 are noise, than all are noise
149
Q

What will be seen if RV lead noise discrimination algorithm determines the signal is noise?

A
  • will see the following in the marker channel
    ) “N” = noise
    ) “NT” = noise timed out
150
Q

What vector does the RV Lead Noise Discrimination algorithm use to check for a far-field signal?

A

can to RVcoil

151
Q

How does the T-wave discrimination algorithm work?

A
  • when rhythm enters the VT/VF zones, it makes an R-wave threshold based on the largest sensed amplitude of the last 3/6 VS events
  • if sensing value is lower, VS events are tentatively labeled as T-waves, then they must meet rate and pattern criteria to be confirmed as true T-waves
152
Q

How do you know that T-wave discrimination is withholding therapy?

A

will see “TW” in marker channel

153
Q

Is the T-wave discrimination algorithm nominally on/off?

A

ON

154
Q

Is the T-wave discrimination algorithm nominally on/off?

A
  • ON in CRT devices
  • OFF in ICD’s
155
Q

What is the purpose of the T-wave discrimination algorithm?

A

to prevent oversensing of T-waves delivery of inappropriate therapy

156
Q

Which feature is used to increase VT detection specificity?

A

Stability

157
Q

Which feature is used to increase VT detection specificity?

A

Stability

158
Q

Is the Stability feature nominally on/off?

A

OFF

159
Q

Which feature avoids unnecessary shocks for rapidly conducted SVTs that enter into the VF zone?

A

SVT Discrimination

160
Q

What is the purpose of the SVT Discrimination?

A

to avoid unnecessary shocks for rapidly conducted SVTs that enter into the VF zone

161
Q

What is the nominal setting for SVT discrimination?

A

260ms for V-V interval

162
Q

What is the term for ATP target area of repolarized tissue between the reentry circuit and the end of the depolarized wavefront?

A

excitable gap

163
Q

Which ATP therapy delivers pulses at quickening rates in a single sequence with the addition of a pulse with each sequence?

A

Ramp

164
Q

Which ATP therapy delivers pulses at the same rate for a given sequence?

A

Burst

165
Q

How does antitachycardia pacing (ATP) work?

A
  • delivers pacing pulses that depolarize the tissue in the excitable gap so the signal from the reentry circuit will land in the depolarized tissue’s ERP (income wave from circuit crashes in to wave from lead).
  • pulses are continued until the lead wave reaches the reentry circuit origin to break it
166
Q

What is the purpose of the Ventricular Rate Stabilization Algorithm?

A
  • rate smoothing algorithm
  • adjusts pacing rate to prevent long pauses following a PVC that may lead to VT
167
Q

What is the purpose of the Atrial Rate Stabilization algorithm?

A
  • rate smoothing algorithm
  • prevents atrial tachycardias by adapting the pacing rate to avoid long sinus pauses following PACs
168
Q

How does the Atrial Rate Stabilization work?

A
  • paces at programmed minimum interval following a PAC
  • then slowly reduces rate based on programmed interval % decrement
169
Q

How does the Atrial Preference Pacing feature work?

A
  • device paces at rate slightly higher than the sinus rate up to a programmable max rate
  • pacing interval is increased by 20ms after a programmable number of “search beats” to look for an intrinsic rhythm
  • when found (AS), the pacing interval is decreased by the programmed “interval decrement” value to increase the pacing rate to slightly higher than sinus rate
  • if AS occurs during pacing, the pacing interval will decrease by the “interval decrement”
170
Q

What are the programmable values for the Atrial Preference Pacing feature?

A
  • search beats: # of beats to pace before APP looks for intrinsic rhythm
  • interval decrement: value by which the pacing interval is decreased when AS event occurs to ensure pacing rate is higher than the intrinsic
  • max rate
171
Q

What are the types of Atrial ATP therapies?

A
  • Burst+
  • Ramp
  • 50 Hz Burst
172
Q

What are the 3 main therapies of ATP?

A
  • Burst
  • Ramp
  • 50 Hz Burst
173
Q

What is Burst+ ATP therapy?

A
  • type of Atrial ATP
  • burst sequence, followed by 2 pulses of Ramp
174
Q

50 Hz Burst defaults to __1__ mode, with __2__ and __3__ backup pacing available.

A

1) AOO
2) VVI
3) VOO

175
Q

What will be seen in the marker channel if an ATP therapy was delivered?

A

“TP”

176
Q

Which feature allows for additional ATP therapies to be delivered if initial therapies were unsuccessful?

A

Reactive ATP

177
Q

What factors will prompt the Reactive ATP algorithm to provide additional ATP therapies?

A
  • change in rate or regularity of the arrhythmia
  • a programmable length of time (nominally q7hrs) has passed after unsuccessful attempts
178
Q

What is the purpose of the Reactive ATP feature?

A

to allow for the delivery of additional ATP therapies to if initial therapies were unsuccessful

179
Q

PR Logic applies to which zones/intervals?

A
  • applied to rhythms falling between SVT limit and slowest detection interval (FDI or TDI)
180
Q

In this example, in what range will PR Logic and Wavelet be applied?
- ex) rate is 375ms (160 bpm)
- SVT limit = 260ms (230 bpm)
- VT zone = 360ms (167 bpm)
- VF zone = 320 (188 bpm)

A
  • will apply to rates slower than 260ms or 230 bpm
181
Q

What are the 3 algorithms that determine if ATP is to be delivered Before or During charge?

A
  • Charge Saver
  • Switchback
  • Smart Mode
182
Q

After a programmed number of successful ATP therapies, which Before/During Charge ATP algorithm will switch from ATP During Charge to Before Charge at next episode?

A

Charge Saver

183
Q

What does the Charge Saver algorithm do?

A
  • after programmed number of successful therapies (nominal 1), switches from ATP During Charge to ATP Before Charge at the next episode
  • device delivers a single ATP sequence without charging at the next episode
184
Q

What does the Switchback algorithm do?

A
  • will switch to ATP During Charge if 2 consecutive ATP (before and after charging) attempts are unsuccessful
185
Q

What does the Smart Mode algorithm do?

A
  • turns off ATP if 4 consecutive ATP sequences (before and after charge) are unsuccessful and 4 shocks are given
  • ATP will not be delivered for further episodes
186
Q

Which algorithm determines the percentage of effective Cardiac Resynchronization Therapy (CRT)?

A

EffectivCRT Diagnostic

187
Q

What is the purpose of the EffectivCRT Diagnostic algorithm?

A

to determine the percentage of effective Cardiac Resynchronization Therapy (CRT)

188
Q

How does the EffectivCRT Diagnostic determine the percentage of effective Cardiac Resynchronization Therapy (CRT)?

A
  • switches EGM3 source to LV to RV coil and evaluates the morphology
  • analyzes 100 consecutive ventricular events every hour and determines the % of effective CRT pacing
  • feature ignores VSP and VSR
  • a ventricular event is considered effective if the LV cathode to RVcoil EGM starts with a negative deflection
189
Q

What criteria needs to be met for EffectivCRT Diagnostic data collection to occur?

A
  • at least one successful device check, since implant
  • LV Amplitude < 8.00 V
  • V. Pacing is LV->RV or LV, or AdaptivCRT is enabled
  • LV Amplitude was not increased and LV Pace Polarity or LV Pulse Width was not changed since the last successful EffectivCRT™ daily device check
190
Q

When is the EffectivCRT device check performed?

A
  • the device check is run 30 minutes after implant and then daily at 01:00
  • pacing is effective if:
    • 4/5 Bi-V paced beats and/or
    • 4/5 LV only paced beats are effective
191
Q

What are the phases of the EffectivCRT during AF feature?

A
  • Initial phase
  • 10 beat evaluation phase
  • 30 second maintenance phase
192
Q

Describe the initial phase of EffectivCRT during AF?

A
  • adjustments are made on a beat-to-beat basis for 30 beats
  • increases rate after each sensed or ineffective CRT pace beat
  • decreases rate after each effective CRT paced beat
193
Q

Describe the 10 beat evaluation phase of EffectivCRT during AF?

A
  • adjusts rates based on current pacing rate and # of effective CRT paces delivered during the phase
194
Q

Describe the 30 second maintenance phase of EffectivCRT during AF?

A
  • maintains current pacing rate and reenters 10 beat evaluation phase at end of 30 seconds
  • if a series of VS events occurs within this phase, immediately reenters the 10-beat evaluation phase
195
Q

When does the device suspend EffectiveCRT during AF feature and default/switch to the Conducted AF Response algorithm?

A
  • suspected LV loss of capture
  • failure of daily check or no successful tests in last 3 days
  • LV amplitude is < 0.5V greater than the last measured LVCM threshold
  • LV amplitude has increased since the last successful daily check
  • 5 or more beats are paced at the Max Rate, 4/5 beats indicate ineffective CRT pacing, and the sensor rate is at least 10 bpm below the max rate
196
Q

When will the device resume EffectivCRT during AF after switching to the Conducted AF Response algorithm?

A

after a successful daily device check

197
Q

When AdaptivBi-V and LV Pacing is programmed, when does the device use Adaptive LV pacing?

A

Need all three:
- HR < 100 and
- 3 consecutive PRI < 220/270 and
- LVCM confirms LV capture

198
Q

When AdaptivBi-V and LV Pacing is programmed, when would the device select Adaptive Bi-V pacing?

A

Only need one:
- HR > 100
- PRI > 220/270 (AV is long)
- LVCM confirms loss of capture

199
Q

What is the goal of Adaptive LV pacing?

A

for LV pacing to occur at the shorter of the below:
- 70% of the intrinsic AV interval
- intrinsic AV - 40ms

200
Q

What is the basic function of Adaptive LV pacing?

A

to pre-pace the LV to synchronize with RV activation

201
Q

What happens to Adaptive LV pacing when a tachyarrhythmia is present or threshold tests are being completed?

A

device switches to non-adaptive Bi-V pacing until the test is completed or the arrhythmia is terminated

202
Q

How does AdaptivCRT assess for intrinsic AV conduction when determining which pacing operation to use (Bi-V vs LV)?

A
  • extends AV delay to 300ms to allow for intrinsic conduction
  • PRI < 220/270 (Adaptive LV)
  • PRI > 220/270 (Bi-V)
203
Q

What is the goal of Adaptive Bi-V pacing?

A

for LV pacing to occur at the shorter of the below:
- end of P-wave + 30ms
- Intrinsic AV - 50ms

204
Q

What is the purpose of the Ventricular Sense Response feature?

A

to prevent CRT pacing inhibition by VS events

205
Q

What is the allowable Ventricular Sense Response pacing percentage?

A

< 10%

206
Q

Does VSR function in tracking or non-tracking modes, or both?

A

works in both

207
Q

What triggers a VSR pace when the feature is operating in the an atrial tracking mode?

A

only responds to VS events during the AV interval

208
Q

T/F: VSR takes precedence over VSP?

A

false; Ventricular Safety Period takes presedence over the Ventricular Sense Response feature

209
Q

What triggers a VSR pace when the feature is operating in the a non-atrial tracking mode?

A

any VS event below the VSR maximum rate triggers an immediate Bi-V or LV pace (VP)

210
Q

Ventricular sensing for VSR occurs thru which lead?

A

RV lead only

211
Q

What will be seen in the marker channel when a VSR pace is delivered?

A

will see VS with 2 pacing spikes (one short, one long)

212
Q

IS VSR nominally on/off?

A

On

213
Q

EffectivCRT during AF shares a maximum rate with which other feature?

A

Conducted AF Response

214
Q

What does CAFR stand for?

A

Conducted AF Response

215
Q

CAFR operates in which mode(s)?

A

non-tracking modes only

216
Q

What is the purpose of the Conducted AF Response algorithm?

A
  • promotes regular vent rate during AF to reduce effects of short-long intervals
  • results in higher ventricular percentage at an avg rate that closely matches the pt’s ventricular response to AT/AF episodes
217
Q

What does Conducted AF Response do?

A
  • adjusts the ventricular pacing rate based on the sensed ventricular activation sequence (VS-VS, VP-VS) and low, med, or high setting
218
Q

What is the maximum bpm CAFR will increase the heart and for what sequence?

A
  • adds max of 3 bpm for sequence of VS-VS
219
Q

What is the CAFR response to a VP-VP sequence:
- low
-medium
-high

A
  • subtracts 1 bpm for all settings with VP-VP sequence
220
Q

What is the CAFR response to a VS-VP sequence:
- low
-medium
-high

A
  • does not change the rate for either setting with VS-VP sequence
221
Q

What is the CAFR response to a VP-VS sequence:
- low
-medium
-high

A
  • adds 1 bpm for all the settings with VP-VS sequence
222
Q

What is the CAFR response to a VP-VP sequence:
- low
- medium
- high

A
  • Low: substracts 1 bpm
  • Med: substracts 1 bpm
  • High: substracts 1 bpm
223
Q

When a device is in an atrial tracking mode, what feature needs to be programmed on to be able to turn on the CAFR algorithm?

A
  • mode switch needs to be on because the CAFR feature will only work in atrial non-tracking modes
224
Q

What is the nominal programmable maximum rate for the Conducted AF Response algorithm?

A

110 bpm

225
Q

What is the CRT benefit of AdaptiveBi-V pacing?

A

optimizes ventricular filling and ejection and eliminate need for manual echo optimization

226
Q

When does the T-wave discrimination algorithm begin looking for T-wave oversensing?

A

When rhythm enters the VT or VF zones

227
Q

When does the Stability algorithm work?

A
  • works in the VT zone
  • begins on 3rd consecutive VT event
228
Q

When does the Stability algorithm determine if a rhythm is unstable and not true VT?

A
  • begins with 3 consecutive VT events
  • compares the 4th ventricular interval to the previous 3
  • if the difference between the 4th interval and any of the previous 3 is greater than the programmed Stability interval, the device classifies the rhythm as unstable
  • therapy is withheld and the VT counter is reset zero
229
Q

Describe how MVP 2.0 dynamic atrial refractory period works?

A
  • HR <75 -> ARP = 600ms
  • HR 75 or greater -> ARP = 75% of R-R cycle lenght
230
Q

What is the difference between MVP AAI timing and traditional AAI?

A

MVP
- PVC inhibits Ap and resets the V-A interval

Traditional AAI
- asynchronous Ap occurs following a PVC
- unneeded Ap since Ventricles have contracted

231
Q

When should MVP not be turned on?

A
  • symptomatic 1st deg AV block
  • suspected 3rd deg AV block
  • symptomatic rate dependent AV block
  • suspected pause-dependent VT
232
Q

How does the blanked flutter search (BFS) mode switch work?

A
  • extends PVARP to uncover blanked Atrial events when:
    • 8 consecutive A-A intervals < TAB (SAV + PVAB) and
    • atrial rate > 1/2 the Mode Switch Detect Rate
  • will mode switch if 2 A events are seen
    • wills see: AR then AS then MS
  • IF NO AS occurs, an AP will be deliverd 30ms after the expected AS and the algorithm will be suspended x 90secs
233
Q

When does Mode Switch determine that the Atrial arrhtymia has ended?

A

If one of the following occurs:
- 7 consecutive A-A intervals < UTR
- 5 consecutive AP events

234
Q

What values are used by the Auto-PVARP algorithm to adjust the PVARP?

A

MAR + 30 bpm (accounts for the wenchebach window)

235
Q

What are the two detection options for Rate Drop Response?

A

Low Rate Detect and Drop Detect

236
Q

What criteria needs to be met for the Rate Drop Response algorith to intervene using the Drop Detect option?

A

All the below is needed:
- Detection type needs to programmed to detect or both
- ventricular rate drops >/= to the programmed drop size for 2 consecutive beats
- vent rate drops to or below the drop rate x 2 consecutive beats
- the two above occur within the detection window

237
Q

What criteria needs to be met for the Rate Drop Response algorith to intervene using the Low Rate Detect option?

A

Ventricular rate falls to below the programmed drop rate for a programmed amount of time

238
Q

Explain the Combined Count “6,7,8 rule”?

A
  • when the combined VF count gets to 6
  • a new CC NID is calculated by (7/6 x original VF NID)
  • after new CC NID is met, device looks back 8 beats
  • if at least one of the 8 is VF, then VF is detected

Ex: VFNID = 12/16
- 7/6 x 12 = 14 -> new NID = 14/16

239
Q

What does the term “4 to abort, 8 to terminate” mean?

A

4 VS events slower than the TDI are need to abort VT/VF therapy and 8 VS events slower thant the TDI are need for the device to determine that a ventricular episode has terminated

240
Q

Explain the AT/AF detection process and therapy delivery?

A
  • onset or mode switch occurs (DDIR)
  • 32 or 40 V-V with 2 or more atrial events = counter is satisfied = detect
  • there is a short interval prior to Rx
  • Rx delivered = counter reset to zero
  • is rhtyhm terminated or redetected (>/= 32 V beats)
241
Q

What does the Sensing Integrity Counter Measure?

A
  • identifies sensing problems
  • short V-V intervals (< 130ms)
  • SIC > 300 will show an observation
242
Q

When does the confirmation window begin after charging for a shock and how long is it?

A
  • the confirmation window begins after the CE
  • window is 400ms
243
Q

How many beats and at what interval are need to abort a shock / VF therapy?

A
  • need 4 consecutive VS with intervals 60ms slower thant the slowest programmed zone
  • applies to VF rhtyhm as well, if VT zone is programmed and VF is detected, all four need to 60ms longer the TDI not the FDI
244
Q

What criteria needs to be met to abort VT therapy?

A

2 consecuting V-V intervals 60ms slower or longer than the TDI

245
Q

What is the difference between confirmation and confirmation+?

A

Confirmation occurs after CE, Confirmation+ occurs before CE

246
Q

What are the 6 criteria that PR Logics exams?

A
  • rate
  • pattern
  • regularity
  • AV dissociation
  • Far Field R-Wave oversensing
  • AT/AF evidence
247
Q

What does the maximum offset value in relation to the Rate Adaptive AV (RAAV) algorithm?

A
  • max amount of time in which the SAV and PAV can be shortened
  • SAV/PAV - max offset = min SAV/PAV at stop rate
248
Q

Which EGM does the RV Lead Noise feature use?

A

EGM2

249
Q

What EMG2 source does the RV Lead Noise Discrimination algorithm use?

A

Can to RVcoil
or
RVcoil to SVC

250
Q

How does the device define a PVC?

A
  • two consecutive ventricular events with no Atrial event in between
251
Q

How much does PVC response extend PVARP following a PVC?

A

PVARP is extended to 400ms to allow for any retrograde P waves to fall into the refractory period and not be tracked

252
Q

Is PMT intervention nominally on or off?

A

Off, need to turn on

253
Q

How do you confirm if PMT is happening?

A

Conduct a V-A conduction test

254
Q

How often does PMT intervention check to see if PMT is present?

A
  • q90 seconds
255
Q

What sequence is seen during a PMT?

A

8 consecutive VP-AS intervals < 400ms

256
Q

How do you diagnose a PMT?

A

Conduct a V-A conduction test by doing a threshold test in VVI mode and looking for retrograde conduction

257
Q

What are the 2 types of mode switch methods?

A
  • AT/AF Onset (counter)
  • 4 of 7 with blanked flutter search
258
Q

What is the criteria for the AT/AF Onset algorithm to mode switch?

A
  • when the AT/AF counter gets to 3 and the median of the 12 A-A intervals is faster than the detection interval
259
Q

Which 2 intervals make up the TAB period?

A

SAV and PVAB

260
Q

What calculation does the Auto-PVARP feature use when adjusting the PVARP value?

A
  • Mean Atrial Rate (MAR) + 30bpm
  • keeps the 2:1 block rate (TARP) 30bpm higher than the MAR
261
Q

How is the mean atrial rate calculated?

A

Use avg of rolling 4 atrial beats

262
Q

What triggers an NCAP window?

A
  • an atrial event (PAC) that falls into PVARP (AR)
263
Q

What is the nominal APP decrement value?

A

50ms

264
Q

What is the purpose of the Atrial Rate Stabilization algorithm?

A

To prevent long pauses or short-long sequences following a PAC known to precede atrial tachyarrhythmias

265
Q

What is the purpose of the rate drop response feature?

A

To prevent syncopal episodes r/t sudden drops in HR

266
Q

What are the 2 rate drop response detection methods?

A
  • low rate detect
  • drop detect
267
Q

How does the Low Rate Detect feature work?

A

Device will pace at the intervention rate for a programmable duration if the pts HR falls to and stays at the LR for a programmable number of confirmation beats

268
Q

Can both rate drop response and rate response be programmed on at the same time?

A

No, its one the other

269
Q

How is PVARP programmed when Rate Drop Response is programmed to On?

A
  • PVARP must be a fixed value and cannot be programmed to “auto”
  • run a retrograde test to determine the appropriate PVARP value
270
Q

Show Mode Switch be programmed On or Off when Rate Drop Response is ON and why?

A
  • program mode switch to OFF, because device will switch into a rate responsive rate and the device cannot look for drop beats while driving the rate at the same time
271
Q

What 3 programming options can be done if a syncopal episode occurs after turning Rate Drop Response on?

A
  • decrease the drop size (fewer drops needed for response)
  • increase the drop rate (response will occur at a higher rate)
  • increase the detection window (more time for the above to occur and generate a response)
272
Q

Sensor rate profile data is collected over what period of time?

A

30 days

273
Q

How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an AS?

A
  • increases the threshold to 75% of the EGM peak up to 8x the programmed value
274
Q

How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an AP?

A
  • the atrial sensitivity is NOT adjusted, only the ventricular sensitivity is increased to 0.45mv following the V event
275
Q

How does the Auto-Adjusting Sensitivity feature adjust the ventricular sensitivity threshold following an VS?

A
  • increases sensitivity threshold to 75% of EGM peak put to 10x the programmed value
276
Q

How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an VP?

A
  • atrial sensitivity threshold is increased to 4x the programmed value up to a max of 2.0mV

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