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
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
3
Q
What is the Ventricular Safety Pacing window length?
A
110ms
4
Q
Ventricular Safety Period (VSP) is available when device is operating in what modes?
A
- DDDR
- DDD
- DDIR
- DDI
- DVIR
- DVI
5
Q
Sensing Assurance helps ensure the appropriate detection of which rhythm(s)?
A
- Atrial Fibrillation
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
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
8
Q
What does the Lead Monitor feature do?
A
measures the impedance of the connected lead(s)
9
Q
What does Implant Detect do?
A
ensures that pacing and sensing polarities are set appropriately at the time of implant
10
Q
What does the Sleep Function do?
A
suspends the programmed lower rate and replaces it with a sleep rate
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
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
13
Q
What does ACR stand for in relation to Atrial Capture Management?
A
Atrial Chamber Reset Method
14
Q
What does AVC stand for in relation to Atrial Capture Management?
A
AV Conduction Method
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
16
Q
What are the 2 Atrial Capture Management (ACM) methods to pacing thresholds?
A
- Atrial Chamber Rest Method (ACR)
- AV Conduction Method (AVR)
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
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
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
20
Q
How often does Atrial Capture Management check threshold measurements?
A
QD at 0100 or 1 am
21
Q
How often does Atrial Capture Management check threshold measurements?
A
QD at 0100 or 1 am
22
Q
Which algorithm measures lead impedances?
A
lead monitor
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
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
25
What happens if device fails Implant Detections 5 min post lead connection bipolar test?
- polarity is permanently set to unipolar
- if lead is bipolar, another test will be performed after 30 minutes
26
What features are suspended until the Implant Detection algorithm/feature is turned off?
- rate response
- managed ventricular pacing (MVP)
- sensing assurance
- capture management (CM)
- diagnostic date collection
27
What happens if the device fails the Implant Detection polarity test done 5 mins after implant?
device is set to unipolar and another test is done after 30 mins
28
How does the sleep function work?
at a set bed time, the lower rate is reduced/changed to programmed sleep rate
29
Is the sleep function nominally on or off?
it is off, needs to be turned on and programmed
30
How does the Single Chamber/Rate Hysteresis algorithm work?
- 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
31
What does the Managed Ventricular Pacing (MVP) algorithm do?
- promotes intrinsic conduction by reducing unnecessary RV pacing
- provides atrial based pacing with ventricular backup
32
What is considered persistent AV conduction loss by the Managed Ventricular Pacing (MVP) feature and what will the device do?
- 2 of 4 most recent beats show loss of ventricular conduction
- device switches to DDDR or DDD mode
33
MVP mode is an appropriate therapy for which type of patient?
pts with SND and good AV conduction
34
What is the goal of the Search AV+ algorithm?
Promotes intrinsic ventricular activity by reducing unnecessary RV pacing
35
How does Search AV+ work?
- 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)
36
What are the zones used by the Search AV+ algorithm to determine how to adjust the SAV/PAV interval?
- 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
37
What does the PM do if the Search AV+ algorithm determines that AV conduction is too long?
Lengthens the SAV and PAV intervals by 62ms to promote intrinsic conduction
38
What does the PM do if the Search AV+ algorithm determines that AV conduction is too short?
Shortens the SAV and PAV intervals by 8ms to promote intrinsic conduction
39
What is the purpose of the Mode Switch feature?
to prevent rapid ventricular pacing r/t the tracking of paroxysmal atrial tachyarrhythmias
40
What does the Mode Switch feature do?
- switches to atrial non-tracking mode (DDIR or VDIR) when an atrial tachyarrhythmia is detected then switches back when episode ceases
41
What are the Mode Switch detection criteria for low power devices (Adapta, Versa, Sensia)?
- if 4 of 7 consecutive A-A are faster then the mode switch rate
- atrial rate is ≥ detection rate and duration criteria is satisfied
42
What is the Blanked flutter search feature in relation to the Mode Switch and how does it work?
- 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
43
What are/is the criteria needed for the Mode Switch feature to return to atrial tracking mode?
- 7 consecutive A-A intervals longer than UTR
or
- 5 consecutive AP occurs
44
Mode Switch and MVP modes adjust pacing according to what criteria?
- pts atrial rhythm and AV conduction status
45
When should the feature Mode Switch be turned on?
- is nominally on after leads are connected
- important if pt has a hx of, or is suspected to have atrial arrhythmias
46
Which feature adapts the pacing rate to changes in the pts physical activity?
Rate Response
47
How does Auto PVARP protect against pacemaker mediated tachycardia (PMT)?
- 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
48
In Advisa PM, ICD and CRT devices, Automatic PVARP makes adjustments based on what?
- pts current HR as measured by the RR median interval
49
In Adapta, Versa, and Sensia PMs, Automatic PVARP makes adjustments based on what?
- 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
50
What is the purpose of the Auto PVARP feature?
- to protect against pacemaker mediated tachycardia (PMT)
- helps keep 2:1 block rate above the UTR
51
What does the Rate Adaptive AV (RAAV) feature do?
- mimics normal physiologic response of shortening AV conduction times w/ increase HR and lengthening w/ decrease in HR
52
What is the purpose of the Rate Adaptive AV (RAAV) feature?
helps keep 2:1 block rate above UTR
53
How does the Rate Adaptive AV (RAAV) feature help keep the 2:1 block rate above the UTR?
- shortens the AV interval for atrial rates within the programmed Start/Stop rate
54
What does the "Start Rate" determine in r/t the RAAV?
rate at which shortening of the SAV and PAV intervals begin
55
What does the "Stop Rate" determine in r/t the RAAV?
rate at which the shortest SAV and PAV interval occur
56
How does shortening the SAV interval increase atrial sensing?
- shortening the total refractory period (TARP) and increasing the 2:1 block rate
57
How does shortening the PAV interval increase atrial sensing?
- lengthen the atrial sensing window of the VA interval at higher sensor driven rates
58
What are the criteria for PMT?
- 8 consecutive VA intervals < 400ms in duration
- start with VP event
- end with AS event
59
How does Pacemaker Mediated Tachycardia Intervention treat PMT?
- increases PVARP to 400ms for one cycle after the 9th VP event
- next atrial event should be an atrial refractory (AR) event
60
What is the cause of PMT?
the sensing and tracking of retrograde P-waves d/t loss of AV synchrony causing ventricular pacing at the UTR
61
Are atrial refractory events tracked by the ventricle?
- no
- atrial events falling with the PVARP do no start SAV timer, therefore are not tracked by the ventricles
62
How does the device confirm PMT prior to lengthening the PVARP by the PMT intervention feature?
- 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
63
Once PMT intervention occurs, the feature is automatically suspended for how long?
85-90 secs (based on device)
64
What is the purpose of PVC Response?
to prevent PMT
65
How does PVC Response prevent PMT?
- extends PVARP 400ms after sensing a PVC
- Atrial events falls within PVARP = not tracked
66
What is the purpose of Non-Competitive Atrial Pacing (NCAP) feature?
- to prevent the triggering of atrial tachycardias
- prevent "competitive pacing"
67
How does the Non-Competitive Atrial Pacing (NCAP) feature prevent atrial tachycardias?
- stops delivery of AP during atrial refractory period
- sense AR event starts 300ms NCAP period, device will not AP in this window
68
What are TDI/FDI?
- programmable zones that identify VF and VT
- Tachy detect interval
- Fibrillation detect interval
69
What type of counter is used to detect VF?
- probabilistic counter
- 30/40 beats = 30 of last 40 beats must be VF for detection to occur
70
What type of counter is used to detect VT?
- consecutive counter
- a VS will reset counter to zero
71
When does the device us a combined count when analyzing a rhythm?
when tachyarrhythmias jump between the Vf and VT detection zones
72
When does the device detect VF using the combined count method?
if any of the last 8 invervals are in the VF zone (FS)
73
When does the device detect Vt using the combined count method?
if 8 of 8 last intervals are in VT zone
74
What are the types of Ventricular ATP?
- burst
- ramp
- ramp+
75
ATP is used to treat?
VT and FVT, arrhythmias with single reentry circuit
76
Cardioversion (RV) is used to treat?
VT and FVT
77
What is the most important step to perform prior to cardioversion?
synchronize and deliver shock on the R-wave
78
What does the defibrillation feature do?
simultaneously depolarizes the heart tissue to restore NSR
79
Defibrillation is used to treat?
VF episodes
80
How do you program VSP in pacemakers?
- is nominally on
- params -> additional features
81
How do you program VSP in ICD?
- is nominally on
- pacing -> params -> additional features
82
In what modes are sensitivity adjustments by the Sensing Assurance feature allowed?
- allowed in VDD and MVP(R)
83
In what modes are sensitivity adjustments by the Sensing Assurance feature not allowed?
- not allowed in AAT/VVT modes
84
How do you turn Sensing Assurance on?
- is nominally on
- params -> atrial/ventricular sensitivity
85
What are the steps taken by the Sensing Assurance feature when adjusting sensitivity values?
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
86
When would the Sensing Assurance feature adjust the sensitivity to the next programmable value that is more sensitive (decrease sensitivity value)?
- if 17 consecutive beats (P- or R- wave) are classified as "Low"
87
When would the Sensing Assurance feature adjust the sensitivity to the next programmable value that is less sensitive (increase sensitivity value)?
- if 36 consecutive beats (P- and/or R-waves) are classified as "High"
88
Auto-adjusting Sensitivity is used to ensure detection of what rhythm(s)?
- fine, variable V-Fib
- A-Fib
89
How is Ventricular CM turned on in pacemakers?
- automatically turned on after Implant Detection is complete
90
How is Ventricular CM turned on in ICDs'/CRT-Ds?
1) params
2) pacing
3) RV amplitude
4) capture management
91
Capture Management will not program ventricular outputs above what value?
- 5.0V or 1.0ms
- will need to be programmed manually
92
What are 3 programming options that promote intrinsic ventricular activaion?
- program long AV delay (SAV/PAV)
- turn on Search AV+
- turn on MVP
93
What are the programming options to manage/prevent Cross-Talk?
- reduce atrial output
- increase vent sensing value (make less sensitive)
- program to bipolar if possible
94
How does the Managed Ventricular Pacing feature know when to mode switch back to AAI-AAIR?
- 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....
95
What is considered transient AV conduction loss by the Managed Ventricular Pacing (MVP) feature and what will the device do?
- 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
96
What is the criteria for the Search AV+ feature to consider an AV interval to short?
- 8/16 VS events occurred within >55ms of scheduled VP
97
What is the criteria for the Search AV+ feature to consider an AV interval to long?
- 8/16 VS events occurred 15ms before scheduled VP or were paced events
98
What is the Search AV+ features response to an AV interval that is too short?
shortens the SAV and PAV by 8ms for 16 beats
99
What is the Search AV+ features response to an AV interval that is too long?
lengthens the SAV and PAV by 62ms for 16 beats
100
What is the Wenchebach safety margin to use when programming the 2:1 block rate (TARP)?
program 2:1 block rate 30bpms higher than the upper tracking rate
101
Why should the 2:1 block rate be programmed to 30bpms higher than the upper tracking rate
to provide a Wenchebach safety window
102
What is the next step if the programmed minimum PVARP value is reached and 2:1 block rate is still lower than the UTR?
shorten the SAV interval increase the 2:1 block rate
103
Which pts should have Auto-PVARP turned on?
pts with chronotropic incompetence, chronic or paroxysmal AF
104
How does the device calculate the mean atrial rate?
looks at a rolling window of 4 beats
105
How does the NCAP feature prevent R-R intervals that are to long following their 300ms window?
feature shortens the SAV following each NCAP window
106
What is the minimum value that the NCAP feature will shorten the SAV interval?
30ms
107
What is the safety margin to use when programming the VT zone?
add 40ms to the pts known VT cycle length
108
What do for the following refer to regarding vectors:
1) HVA
2) HVB
3) HVX
1) can
2) RV coil
3) extra, usually the SVC coil
109
What does TF with a dot next to the F (TF∙) mean when seen in the marker channel?
- FVT via VF is programmed
- beat falls in FVT via VF zone
110
What does TF with a vertical line next to the F mean when seen in the marker channel?
- last 8 beats are in the FVT via VF zone
- FVT is detected
111
What does TF with a vertical line next to the F mean when seen in the marker channel?
- one of last 8 intervals is FVT
- FVT detected
112
What does TF with a dot next to the T (T∙F) mean when seen in the marker channel?
- FVT via VT is programmed
- beat falls in FVT via VT zone
113
What is the purpose of the Wavelet feature?
to prevent the inappropriate detection and tx of ventricular arrhythmias
114
How does the Wavelet feature work?
- creates template of the pts intrinsic rhythm to use a comparison when suspected ventricular arrhythmias occur
115
When does the wavelet feature consider withhold detection and tx?
- when 3/8 of the last QRS waveforms meet the match threshold percentage
- nominally 70%
116
Is the wavelet feature nominally on/off?
On
117
Does the wavelet feature work at initial detection (NID), redetection (RNID) or both?
only at initial detection
118
What is the purpose of the PR Logic feature?
to differentiate between SVT and true VT/VF and to withhold inappropriate VT/VF therapies
119
Does the PR Logic feature work at initial detection (NID), redetection (RNID) or both?
only at initial detection
120
Is PR Logic nominally on/off?
On with SVT V. Limit at 260ms
121
Does the RV Lead Noise Discrimination algorithm work at initial detection (NID), redetection (RNID) or both?
both; detect and redetect
122
Does the T-Wave Discrimination algorithm work at initial detection (NID), redetection (RNID) or both?
both; detect and redetect
123
The Onset feature applies to which zones?
VT and FVT via VT zones only
124
When is the Onset algorithm applied when analyzing a rhythm?
applied at pre-counting
125
What is the purpose of the Stability feature?
to increase VT detection specificity
126
The Stability feature is applied in which zone(s)?
VT zone only at detection and redetection
127
Which feature avoids long sinus pauses by pacing at a programmed minimum interval after a PAC, then slowly reduces the rate?
Atrial Rate Stabilization
128
Which feature avoids long sinus pauses by pacing at a programmed minimum interval after a PVC, then slowly reduces the rate?
Ventricular Rate Stabilization
129
What is the purpose of the Post Mode Switch Overdrive Pacing (PMOP) feature?
- to prevent early recurrence of AF (ERAF)
130
Which feature is meant to prevent early recurrence of AF (ERAF?)
Post Mode Switch Overdrive Pacing (PMOP)
131
How does the Post Mode Switch Overdrive Pacing (PMOP) feature work?
- 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
What is/are the criteria for mode switch to occur in high power devices?
- 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
What is the nominal switch interval for Mode Switch feature?
350ms or appx 175bpm
134
How do you know that Mode Switch occurred when interrogating a device?
when reviewing episodes, "MS" will be seen in the channel marker
135
What are the Mode Switch detection criteria for Advisa DR MRI™, Revo MRI™, EnRhythm™, Consulta™ CRT-P, Syncra™ CRT-P and Medtronic ICDs?
- 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
What is the purpose of Atrial Preference Pacing?
- 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
Up to how long will cardiac compass store data?
up to 14 months
138
What is an electrical storm as it relates to a PM or ICD?
when the patient experiences 3 or more appropriate VT therapies in a 24hr period
139
What is the term for when the patient experiences 3 or more appropriate VT therapies in a 24hr period?
electrical storm
140
Which feature measures intrathoracic impedance changes over time?
OptiVol
141
When does OptiVol begin collecting data?
34 days after implantation to allow for pocket maturation
142
What is the nominal OptiVol threshold?
60
143
How does the OptiVol feature collect data?
sends impulse from the RVcoil to the can at 20min intervals bewtween 1200-1700
144
How do you turn on OptiVol?
is automatically turned on 34 days after implant
145
What is the name for the programmable value that is the maximum duration PR Logic can withhold VT/VF detection and therapies?
high-rate timeout
146
When does PR Logic determine if far-field R waves are present?
- 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
Which feature suppresses atrial ectopic beats that may lead to atrial arrhythmias by pacing at rate slightly higher than sinus rate?
Atrial Preference Pacing
148
How does the RV lead noise discrimination algorithm prevent delivery of therapy d/t noise?
- 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
What will be seen if RV lead noise discrimination algorithm determines the signal is noise?
- will see the following in the marker channel
) "N" = noise
) "NT" = noise timed out
150
What vector does the RV Lead Noise Discrimination algorithm use to check for a far-field signal?
can to RVcoil
151
How does the T-wave discrimination algorithm work?
- 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
How do you know that T-wave discrimination is withholding therapy?
will see "TW" in marker channel
153
Is the T-wave discrimination algorithm nominally on/off?
ON
154
Is the T-wave discrimination algorithm nominally on/off?
- ON in CRT devices
- OFF in ICD’s
155
What is the purpose of the T-wave discrimination algorithm?
to prevent oversensing of T-waves delivery of inappropriate therapy
156
Which feature is used to increase VT detection specificity?
Stability
157
Which feature is used to increase VT detection specificity?
Stability
158
Is the Stability feature nominally on/off?
OFF
159
Which feature avoids unnecessary shocks for rapidly conducted SVTs that enter into the VF zone?
SVT Discrimination
160
What is the purpose of the SVT Discrimination?
to avoid unnecessary shocks for rapidly conducted SVTs that enter into the VF zone
161
What is the nominal setting for SVT discrimination?
260ms for V-V interval
162
What is the term for ATP target area of repolarized tissue between the reentry circuit and the end of the depolarized wavefront?
excitable gap
163
Which ATP therapy delivers pulses at quickening rates in a single sequence with the addition of a pulse with each sequence?
Ramp
164
Which ATP therapy delivers pulses at the same rate for a given sequence?
Burst
165
How does antitachycardia pacing (ATP) work?
- 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
What is the purpose of the Ventricular Rate Stabilization Algorithm?
- rate smoothing algorithm
- adjusts pacing rate to prevent long pauses following a PVC that may lead to VT
167
What is the purpose of the Atrial Rate Stabilization algorithm?
- rate smoothing algorithm
- prevents atrial tachycardias by adapting the pacing rate to avoid long sinus pauses following PACs
168
How does the Atrial Rate Stabilization work?
- paces at programmed minimum interval following a PAC
- then slowly reduces rate based on programmed interval % decrement
169
How does the Atrial Preference Pacing feature work?
- 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
What are the programmable values for the Atrial Preference Pacing feature?
- 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
What are the types of Atrial ATP therapies?
- Burst+
- Ramp
- 50 Hz Burst
172
What are the 3 main therapies of ATP?
- Burst
- Ramp
- 50 Hz Burst
173
What is Burst+ ATP therapy?
- type of Atrial ATP
- burst sequence, followed by 2 pulses of Ramp
174
50 Hz Burst defaults to __1__ mode, with __2__ and __3__ backup pacing available.
1) AOO
2) VVI
3) VOO
175
What will be seen in the marker channel if an ATP therapy was delivered?
"TP"
176
Which feature allows for additional ATP therapies to be delivered if initial therapies were unsuccessful?
Reactive ATP
177
What factors will prompt the Reactive ATP algorithm to provide additional ATP therapies?
- change in rate or regularity of the arrhythmia
- a programmable length of time (nominally q7hrs) has passed after unsuccessful attempts
178
What is the purpose of the Reactive ATP feature?
to allow for the delivery of additional ATP therapies to if initial therapies were unsuccessful
179
PR Logic applies to which zones/intervals?
- applied to rhythms falling between SVT limit and slowest detection interval (FDI or TDI)
180
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)
- will apply to rates slower than 260ms or 230 bpm
181
What are the 3 algorithms that determine if ATP is to be delivered Before or During charge?
- Charge Saver
- Switchback
- Smart Mode
182
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?
Charge Saver
183
What does the Charge Saver algorithm do?
- 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
What does the Switchback algorithm do?
- will switch to ATP During Charge if 2 consecutive ATP (before and after charging) attempts are unsuccessful
185
What does the Smart Mode algorithm do?
- 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
Which algorithm determines the percentage of effective Cardiac Resynchronization Therapy (CRT)?
EffectivCRT Diagnostic
187
What is the purpose of the EffectivCRT Diagnostic algorithm?
to determine the percentage of effective Cardiac Resynchronization Therapy (CRT)
188
How does the EffectivCRT Diagnostic determine the percentage of effective Cardiac Resynchronization Therapy (CRT)?
- 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
What criteria needs to be met for EffectivCRT Diagnostic data collection to occur?
- 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
When is the EffectivCRT device check performed?
- 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
What are the phases of the EffectivCRT during AF feature?
- Initial phase
- 10 beat evaluation phase
- 30 second maintenance phase
192
Describe the initial phase of EffectivCRT during AF?
- 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
Describe the 10 beat evaluation phase of EffectivCRT during AF?
- adjusts rates based on current pacing rate and # of effective CRT paces delivered during the phase
194
Describe the 30 second maintenance phase of EffectivCRT during AF?
- 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
When does the device suspend EffectiveCRT during AF feature and default/switch to the Conducted AF Response algorithm?
- 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
When will the device resume EffectivCRT during AF after switching to the Conducted AF Response algorithm?
after a successful daily device check
197
When AdaptivBi-V and LV Pacing is programmed, when does the device use Adaptive LV pacing?
Need all three:
- HR < 100 and
- 3 consecutive PRI < 220/270 and
- LVCM confirms LV capture
198
When AdaptivBi-V and LV Pacing is programmed, when would the device select Adaptive Bi-V pacing?
Only need one:
- HR > 100
- PRI > 220/270 (AV is long)
- LVCM confirms loss of capture
199
What is the goal of Adaptive LV pacing?
for LV pacing to occur at the shorter of the below:
- 70% of the intrinsic AV interval
- intrinsic AV - 40ms
200
What is the basic function of Adaptive LV pacing?
to pre-pace the LV to synchronize with RV activation
201
What happens to Adaptive LV pacing when a tachyarrhythmia is present or threshold tests are being completed?
device switches to non-adaptive Bi-V pacing until the test is completed or the arrhythmia is terminated
202
How does AdaptivCRT assess for intrinsic AV conduction when determining which pacing operation to use (Bi-V vs LV)?
- extends AV delay to 300ms to allow for intrinsic conduction
- PRI < 220/270 (Adaptive LV)
- PRI > 220/270 (Bi-V)
203
What is the goal of Adaptive Bi-V pacing?
for LV pacing to occur at the shorter of the below:
- end of P-wave + 30ms
- Intrinsic AV - 50ms
204
What is the purpose of the Ventricular Sense Response feature?
to prevent CRT pacing inhibition by VS events
205
What is the allowable Ventricular Sense Response pacing percentage?
< 10%
206
Does VSR function in tracking or non-tracking modes, or both?
works in both
207
What triggers a VSR pace when the feature is operating in the an atrial tracking mode?
only responds to VS events during the AV interval
208
T/F: VSR takes precedence over VSP?
false; Ventricular Safety Period takes presedence over the Ventricular Sense Response feature
209
What triggers a VSR pace when the feature is operating in the a non-atrial tracking mode?
any VS event below the VSR maximum rate triggers an immediate Bi-V or LV pace (VP)
210
Ventricular sensing for VSR occurs thru which lead?
RV lead only
211
What will be seen in the marker channel when a VSR pace is delivered?
will see VS with 2 pacing spikes (one short, one long)
212
IS VSR nominally on/off?
On
213
EffectivCRT during AF shares a maximum rate with which other feature?
Conducted AF Response
214
What does CAFR stand for?
Conducted AF Response
215
CAFR operates in which mode(s)?
non-tracking modes only
216
What is the purpose of the Conducted AF Response algorithm?
- 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
What does Conducted AF Response do?
- adjusts the ventricular pacing rate based on the sensed ventricular activation sequence (VS-VS, VP-VS) and low, med, or high setting
218
What is the maximum bpm CAFR will increase the heart and for what sequence?
- adds max of 3 bpm for sequence of VS-VS
219
What is the CAFR response to a VP-VP sequence:
- low
-medium
-high
- subtracts 1 bpm for all settings with VP-VP sequence
220
What is the CAFR response to a VS-VP sequence:
- low
-medium
-high
- does not change the rate for either setting with VS-VP sequence
221
What is the CAFR response to a VP-VS sequence:
- low
-medium
-high
- adds 1 bpm for all the settings with VP-VS sequence
222
What is the CAFR response to a VP-VP sequence:
- low
- medium
- high
- Low: substracts 1 bpm
- Med: substracts 1 bpm
- High: substracts 1 bpm
223
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?
- mode switch needs to be on because the CAFR feature will only work in atrial non-tracking modes
224
What is the nominal programmable maximum rate for the Conducted AF Response algorithm?
110 bpm
225
What is the CRT benefit of AdaptiveBi-V pacing?
optimizes ventricular filling and ejection and eliminate need for manual echo optimization
226
When does the T-wave discrimination algorithm begin looking for T-wave oversensing?
When rhythm enters the VT or VF zones
227
When does the Stability algorithm work?
- works in the VT zone
- begins on 3rd consecutive VT event
228
When does the Stability algorithm determine if a rhythm is unstable and not true VT?
- 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
Describe how MVP 2.0 dynamic atrial refractory period works?
- HR <75 -> ARP = 600ms
- HR 75 or greater -> ARP = 75% of R-R cycle lenght
230
What is the difference between MVP AAI timing and traditional AAI?
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
When should MVP not be turned on?
- symptomatic 1st deg AV block
- suspected 3rd deg AV block
- symptomatic rate dependent AV block
- suspected pause-dependent VT
232
How does the blanked flutter search (BFS) mode switch work?
- 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
When does Mode Switch determine that the Atrial arrhtymia has ended?
If one of the following occurs:
- 7 consecutive A-A intervals < UTR
- 5 consecutive AP events
234
What values are used by the Auto-PVARP algorithm to adjust the PVARP?
MAR + 30 bpm (accounts for the wenchebach window)
235
What are the two detection options for Rate Drop Response?
Low Rate Detect and Drop Detect
236
What criteria needs to be met for the Rate Drop Response algorith to intervene using the Drop Detect option?
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
What criteria needs to be met for the Rate Drop Response algorith to intervene using the Low Rate Detect option?
Ventricular rate falls to below the programmed drop rate for a programmed amount of time
238
Explain the Combined Count “6,7,8 rule”?
- 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
What does the term “4 to abort, 8 to terminate” mean?
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
Explain the AT/AF detection process and therapy delivery?
- 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
What does the Sensing Integrity Counter Measure?
- identifies sensing problems
- short V-V intervals (< 130ms)
- SIC > 300 will show an observation
242
When does the confirmation window begin after charging for a shock and how long is it?
- the confirmation window begins after the CE
- window is 400ms
243
How many beats and at what interval are need to abort a shock / VF therapy?
- 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
What criteria needs to be met to abort VT therapy?
2 consecuting V-V intervals 60ms slower or longer than the TDI
245
What is the difference between confirmation and confirmation+?
Confirmation occurs after CE, Confirmation+ occurs before CE
246
What are the 6 criteria that PR Logics exams?
- rate
- pattern
- regularity
- AV dissociation
- Far Field R-Wave oversensing
- AT/AF evidence
247
What does the maximum offset value in relation to the Rate Adaptive AV (RAAV) algorithm?
- max amount of time in which the SAV and PAV can be shortened
- SAV/PAV - max offset = min SAV/PAV at stop rate
248
Which EGM does the RV Lead Noise feature use?
EGM2
249
What EMG2 source does the RV Lead Noise Discrimination algorithm use?
Can to RVcoil
or
RVcoil to SVC
250
How does the device define a PVC?
- two consecutive ventricular events with no Atrial event in between
251
How much does PVC response extend PVARP following a PVC?
PVARP is extended to 400ms to allow for any retrograde P waves to fall into the refractory period and not be tracked
252
Is PMT intervention nominally on or off?
Off, need to turn on
253
How do you confirm if PMT is happening?
Conduct a V-A conduction test
254
How often does PMT intervention check to see if PMT is present?
- q90 seconds
255
What sequence is seen during a PMT?
8 consecutive VP-AS intervals < 400ms
256
How do you diagnose a PMT?
Conduct a V-A conduction test by doing a threshold test in VVI mode and looking for retrograde conduction
257
What are the 2 types of mode switch methods?
- AT/AF Onset (counter)
- 4 of 7 with blanked flutter search
258
What is the criteria for the AT/AF Onset algorithm to mode switch?
- when the AT/AF counter gets to 3 and the median of the 12 A-A intervals is faster than the detection interval
259
Which 2 intervals make up the TAB period?
SAV and PVAB
260
What calculation does the Auto-PVARP feature use when adjusting the PVARP value?
- Mean Atrial Rate (MAR) + 30bpm
- keeps the 2:1 block rate (TARP) 30bpm higher than the MAR
261
How is the mean atrial rate calculated?
Use avg of rolling 4 atrial beats
262
What triggers an NCAP window?
- an atrial event (PAC) that falls into PVARP (AR)
263
What is the nominal APP decrement value?
50ms
264
What is the purpose of the Atrial Rate Stabilization algorithm?
To prevent long pauses or short-long sequences following a PAC known to precede atrial tachyarrhythmias
265
What is the purpose of the rate drop response feature?
To prevent syncopal episodes r/t sudden drops in HR
266
What are the 2 rate drop response detection methods?
- low rate detect
- drop detect
267
How does the Low Rate Detect feature work?
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
Can both rate drop response and rate response be programmed on at the same time?
No, its one the other
269
How is PVARP programmed when Rate Drop Response is programmed to On?
- PVARP must be a fixed value and cannot be programmed to “auto”
- run a retrograde test to determine the appropriate PVARP value
270
Show Mode Switch be programmed On or Off when Rate Drop Response is ON and why?
- 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
What 3 programming options can be done if a syncopal episode occurs after turning Rate Drop Response on?
- 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
Sensor rate profile data is collected over what period of time?
30 days
273
How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an AS?
- increases the threshold to 75% of the EGM peak up to 8x the programmed value
274
How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an AP?
- the atrial sensitivity is NOT adjusted, only the ventricular sensitivity is increased to 0.45mv following the V event
275
How does the Auto-Adjusting Sensitivity feature adjust the ventricular sensitivity threshold following an VS?
- increases sensitivity threshold to 75% of EGM peak put to 10x the programmed value
276
How does the Auto-Adjusting Sensitivity feature adjust the atrial sensitivity threshold following an VP?
- atrial sensitivity threshold is increased to 4x the programmed value up to a max of 2.0mV
