Brady

Question 1

ALR

Answer 1

Goal:
Automatically detects lead insertion to exit storage mode, measure lead impedance and detect polarity

Algo:

• If RV lead is between 200-2000Ω and bipolar, bipolar configuration retained
• If RV lead is out of 200-2000Ω, out of range unipolar is retained and ALR keeps monitoring RV impedance for 2h until in-range bipolar lead is detected

Details:
Nominally ON
Programmable ON/OFF

Question 2

AGC

Pacemaker Sensing

Answer 2

Goal:
One of the two sensing methods (the other one is Fixed).
Dynamically adjusts the sensitivity in both the atrium and ventricle to detect intrinsic activity

Algo:

• If AGC FLOOR is NOMINAL A = 0.25mV & V = 0.6mV), EGM PEAK A = 2.4mV & V = 4.8mV
• Else if AGC FLOOR is A ≥ 0.3mV or V > 0.6mV, EGM PEAK = 8 x AGC FLOOR

Details:
Only with bipolar leads
- Slow AGC: calculates a search area, using average of previous peaks with MIN and MAX amplitude
- Fast AGC: Senses the peak, holds activity at MAX, stepsdown gradually and reaches MIN until next beat

Question 3

DNA

Pacemaker Sensing

Answer 3

Goal:
Helps filter myopotentials and EMI to keep AGC FLOOR above noise level

Algo:

Details:
Always ON when AGC ON

Question 4

Smart Blanking

Pacemaker Sensing

Answer 4

Goal:
Optimises sensing capability of the device to avoid crosstalk (far-field detection of the opposite chamber)

Algo:
Blanking after As, Vs & Vp (As signal is too weak to cause crosstalk):
- 15ms after sensed
- 37.5ms after paced

When blanking:
If AGC level > 3/8 EGM PEAK, AGC level decrease continues where it paused
Else if AGC level ≤ 3/8 EGM PEAK, AGC level decrease continues starting from 3/8 of EGM PEAK

Details:
Only with AGC

Question 5

Dynamic AV Delay

Answer 5

Goal:
Provides a more physiologic response to rate changes by mimicking the shortening of the PR interval with the increase in heart rate

Algo:

Details:
Sensed & Paced AV Delay have the same effective duration, sensed is usually shorter because of the time it takes the P-wave to reach minimum amplitude for detection
AV Delay is at its maximum at LRL, and at its minimum at MTR

Question 6

PMT Prevention & Termination

Pacemaker Mediated Tachycardia Management

Answer 6

Goal:
Avoid Infinite loops of PAC Vp

Algo:

• Prevention: PVARP extended to 400ms when AV synchrony might be lost
• Termination: PVARP extended to 500ms after 16 cycles of PAC Vp at MTR to force an As to appear during PVARP and break the loop

Details:
PMT can be induced by A LOC or undersensing, PVC, PAC, myopotential tracking…
Vp electrical impulse re-enters the atrium causing a PAC, followed again by Vp at MTR.

Question 7

ATR

Atrial Arrhythmia Management

Answer 7

Goal:
Limits the amount of time that the ventricle paces to follow A-arrhythmias, limits the MTR Vp in response to A-tach
For patients with A rate > V rate

Algo:
If 8 As > Atrial Rate Cutoff, Entry Count is met
Then if 8 Vp Duration is met, Fallback Mode (DDD to DDI or VDI) to avoid P-wave tracking
Then if 8 As < Atrial Rate Cutoff, Exit Count is met
Then mode switch back to programmed mode

Details:
Atrial Rate Cutoff = 220 - patient’s age

Question 8

AFR

Atrial Arrhythmia Management

Answer 8

Goal:
Limits the amount of time that the ventricle paces to follow A-arrhythmias
Provides immediate non-tracking of A rate > AFR rate
Maintain non-tracking behaviour as long as As exceed AFR trigger rate to prevent Vp during vulnerable periods following As

Algo:
When As occurs during PVARP, AFR Window opens
If As occurs happens during AFR Window, AFR window restarts and Vp at LRL until flutter eliminated
If AFR Window ends < 50ms before sheduled Vp LRL: no Ap
Else if AFR Window ends > 50 ms before scheduled Vp LRL: Ap

Details:

Question 9

APP

Atrial Fibrillation Prevention

Answer 9

Goal:
Promotes Ap by increasing Ap rate when non-PAC, non-refractory As events occur (so Ap rate > As rate)

Algo:
If As-Vs or As-Vp, decrease of VA interval on the next cycle (-10ms) until Ap

Details:
In DDD or DDI
Not compatible with ATR
The pacing rate gradually decreased back down to the LRL by lenghthening the VA interval by 10ms if 4 consecutive cycles of any of the following:
- As during refractory period
- Absence of A event
- PAC

Question 10

ProACt

Answer 10

Goal:
Increases the Ap rate in presence of PACs in order to increase the likelyhood of Ap

Algo:
If previous event was PAC, V-V interval reduced to 75% of previous cycle
After periods of Ap without PAC, pacing decreases back to LRL
If nAp or nAs: Search Interval (4 cycles), VA interval +10ms

Details:
- As classified as PAC if:
Previous AA interval was less than 75% of the average 4 previous intervals
- Is less than 600ms

Question 11

VRR

Rate Control

Answer 11

Goal:
Reduces V-V cycle length during partially conducted A-arrhythmias by modestly increasing Vp rate
Calculates a VRR indicated pacing interval based on a weighted sum of the current V-V cycle length and the previous VRR indicated pacing interval

Algo:

Details:
Calculation to average the R-R rate and the interval difference
When AF, it allows the RV to pace slightly faster to regularise rate and interval difference

Question 12

Rate Smoothing

Answer 12

Goal:
Smooth large cycle to cycle variations in rate by preventing paced intervals by changing more than a percentage from one cycle to another
- Rate Smoothing Up: controls the largest increase allowed in rate
- Rate Smoothing Down: controls the largest decrease allowed in rate

Algo:
Rate Smoothing Up / Down, nominally OFF, 3 - 25%
MPR 30 - 185 ppm, nominally 130 ppm
Based on the most recent R-R interval stored in memory and programmed Rate Smoothing Value, the PG sets up the two synchronisation windows for the next cycle, one for the atrium and one for the ventricle

Details:
Not available when:
- 8 cycles window of Rate Search Hysteresis
- During ATR Fallback
- If VRR active
- When PMT termination is triggered
- Right after reprogramming LRL
- If intrinsic rate is > MTR
- If APP/ProACt, Rate Smoothing Up is not applied

Not compatible with SBR

Question 13

SBR

Answer 13

Goal:
SBR activates when the atrial chamber has been continuously sensed for one minute (non-programmable), followed by a sudden decrease in atrial such that atrial pacing occurs at LRL or SIR for a programmable amount of cycles

Algo:
- Atrial Paces Before Therapy: 1 - 8 paces, nominally 3 paces
Amount of Ap at LRL or SIR to validate SBR
- SBR Atrial Pacing Rate Increase:
5 - 40 bpm, nominally 20 bpm
5 to 40 bpm + average atrial rate, never above MTR or SIR
- SBR therapy duration: 1 - 15 minutes nominally 2 minutes
Once SBR atrial pacing has been delivered for SBR therapy duration, Ap rate decreases by using a Rate Smoothing Down 12% until LRL or SIR

Details:
SBR Inhibit during rest nominally ON
Makes the difference between SB and rest, uses MV
SBR not available with APP/ProACt enabled
SBR does not activate during ATR Fallback

Question 14

Rate Hysteresis

Pacing Avoidance

Answer 14

Goal:
Extends the Escape interval to promote As below LRL
Hysteresis Search periodically searches for intrinsic rhythm below the LRL to promote intrinsic activity

Algo:
Search frequency programmable, extension for up to 8 cycles
If no As after 8 cycles, back to LRL or SIR pacing
Programmable Hysteresis Offset

Details:
In CRTs DDD and AAI
In PMs/ICDs DDD, DDI, VVI, AAI
Not available in Rate Response modes, VDD, ATR Fallback modes

Rate Smoothing remains active during Rate Hysteresis, but disabled dyring Hysteresis Search Interval

Question 15

AV Search +

Answer 15

Goal:
Promote intrinsic AV conduction by allowing AV conduction to occur beyond the programmed AV Delay, thus avoiding unnecessary Vp
For patients with exercise-dependent 1st degree or 2nd degree AV Block

Algo:
Lenghthens the AV Delay during AV Search +
Search occurs every 32 - 1024 cycles
Search AV Delay: 30 - 400ms
Lenghthened AV Delay remains until:
- 8 cycles search expires without any Vs
- Vp in a 10 cycles rolling window

Details:
In DDD(R), DDI(R), VDD(R)
Nominally ON
Not compatible with Dynamic AV Delay (Sensed and Paced)
Extendion is not taken into account for TARP calculation in order to avoid Wenckebach behaviour

Question 16

RYTHMIQ

Answer 16

Goal:
Promote intrinsic ventricular conduction by adapting the pacing mode to the patient’s pacing conditions, prevents unnecessary paces

Algo:
AAI(R) programmed at LRL with VVI backup at LRL - 15 bpm
Av conduction loss parameters:
Vp or Vs > 150ms slower than LRL or SIR
3/11 blocks in a rolling window
Then switch to DDD(R)

Sustained conduction: AV Search + active to search for intrinsic Vs, success if 25 consecutive Vs (switch back to AAI VVI, fail if 2/10 Vp in a rolling window (stays in DDD)

Details:
Not compatible with APP/ProACt
SBR not responding when RYTHMIQ on AAI(R)
ATR On & Rate Smoothing ON in RUTHMIQ DDDR

DO NOT FORGET TO TURN OFF AV SEARCH + WHEN TURNING OFF RYTHMIQ

Question 17

MV

Answer 17

Goal:
Adapt pacing according to patient’s activity checked through impedance measurements of the lungs and MV
MV = TV x RR
MV Respiratory Sensor Signal of 320µA at 20Hz to create an electric field that, once measured, provides impedance (high at inspiration, low at expiration)
Uses a long term and short term baseline to assess metabolic demand

Algo:

• If MV-short term > MV-long term: SIR increases (up to +/-2 ppm per cycle)
• Response Factor: Increase MV caused by increase in metabolic demand, detected by the PG causing increase in pacing rate
• Ventilatory Threshold: programmable, age and gender matter, anaerobic threshold (70 - 80% of max HR), if above, creation of CO2 and lactic acid
• Ventilatory Threshold Response: programmable, response to the point in exercise when RR > HR
• Ventilatory Threshold Response Factor: nominally 70%, % of MV response applied when SIR > Ventilatory Threshold Rate (low for young and active patients)
• Activity level: sedentary, active, athletic, endurance sports

Details:
ON in DDDR
PASSIVE in DDD
In addition to Automatic Calibration 2h after leads attach, the device will initiate an Automatic Calibration under the following circumstances:
- If MV is turned OFF and then back ON
- After an MV vector change
- After device reset

Manual programming:

• Successful: Rate Response will occur within 1 minute of completion
• Unsuccessful: Automatic Calibration initiated

Step 1: assess chronotropic incompetence (if HR score > 50, Rate Response might be good)
Step 2: prepare calibration and sensor baseline (ask for moderate activity for calibration)
Step 3: optimise sensor trnding data

MV Sensor Signal: 320µA every 50ms, possibility to be oversensed (but monitored by SAM) as ATR, VT, non-sustained VT

Question 18

XL

Answer 18

Goal:
Adapt pacing capabilities depending on the level of activity of the patient, pacing at MSR with a certain response factor between rest and physical activity, starting to adapt pacing at a defined activity threshold, with a defined reaction time, and then recovering at a set recovery time

Algo:
- MSR: determines the max sensor rate; indeependently programmable from MTR
MSR 50 - 185 bpm, nominally 130 bpm
- Response Factor: determines the pacing rate incresase that will occur above the LRL at various levels of activity of the patient activity
1 - 16, nominally 8
- Activity Threshold: represents the activity level that must be exceeded before the sensor-driven pacing rate will increase
Very low - very high, nominally medium
- Reaction time: determines how quickly the pacing rate will rise to a new level once an increase in activity is detected
10 - 50s, nominally 3s
- Recovery time: determines the time required for the paced rate to decrease back to the LRL in the absence of activity
2 - 16min, nominally 2 min

Details:
PASSIVE, cannot be turned OFF during calibration
In all permanent and ATR Fallback modes (all BSCI pacemakers)

Question 19

SAM

Answer 19

Goal:
Avoid MV Sensor Signal to be oversensed
Continuous surveillance of RA/RV EGM for MV Sensor Signal artifacts that may result in oversensing

Algo:
If an artifact is detected, within approx. 1s:
- MV Sensor Signal vector impedance(s) (ring to can, tip to can) and pacing lead(s) impedance(s) are measured
- A SAM episode is created with EGM and measured impedance values are reported
- And SAM will either switch MV vector or disable the MV Sensor Signal

Details:
To reduce the risk of pacing inhibition due to MV oversensing, BSCI recommends SAM to remain enabled whenever the MV Sensor Signal is enabled
In most cases when an artifact is detected, SAM will first try to switch the Sensor Signal vector, if not possible disable it

Question 20

RVAC

Answer 20

Goal:
Automatic Capture is designed to maintain adequate capture safety margins and also increase battery longevity
Automatically adjust the RVp output to ensure capture of the ventricle by optimising the output voltage to 0.5V above capture threshold

Algo:
Output between 0.7 - 3V
Pulse width fixed at 0.4ms

• Ambulatory Threshold test: RVAC determines a new Vp threshold after a LOC or every 21h
• Beat to beat: pacing output = ambulatory threshold + 0.5V at 0.4ms
  Capture verification at every pace, if LOC:
  Backup pace 70ms after LOC at ambulatory threshold + 1.5V
  Output of backup: 3.5 - 5V
  If 2 LOC in 4 cycles rolling window: ‘Confirmed LOC’
• Suspension mode:when Confirmed LOC or unsuccessful test
  output = previous threshold x 2
  3.5 - 5V
  PG stays in Suspension mode until next Ambulatory Threshold Test (3 tests per day, lead alert if 4 days without successful test)

Details:
DDD(R), DDI(R), VDD(R), VVI(R), VDI(R)
Measures every 21h the pacing threshold between 0.2V and 3V at 0.4ms
Functions with low or high impedance leads, uni or bipolar

Question 21

RAAT

Answer 21

Goal:
Designed to dynamically adjust the Ap output to ensure capture of the atrium by optimising the output voltage to 2x the capture threshold to provide an adequate safety margin (for thresholds ≤ 2.5V)

Algo:
- Ambulatory Threshold Test every 21h
If successful : normal operation, output = 2 x max of last 7 thresholds at 0.4ms
Esle up to 3 test a day, if no successful test after 4 days, Lead Alert and Suspension Mode 5V at 0.4ms

Details:
DDD(R), DDI(R), DDI(R) fallback
RA bipolar lead required with a functional RV lead

During measurements:

• mode remains unchanged (unless RYTHMIQ ON in AAIR, in which case switch to DDDR for the test)
• Starting test pacing amplitude is the current RAAT programmed output
• The pacing amplitude of the test decreases in 0.5V steps above 3.5V, and in 0.1V steps under 3.5V
• Paced AV Delay = 85ms
• Sensed AV Delay = 55ms
• Initial pacing rate is set to the average atrial rate, LRL or SIR, whichever is faster
• If insufficient Ap or fusion, +10 bpm but never above 110 bpm, MSR, MTR, MPR, SIR or 5 bpm below VT detection

To ensure that LOC during RAAT does not trigger PMT, the PG uses the PMT prevention algorithm by extending the PVARP to 500ms in order to prevent from tracking any subsequent P-wave