Summary of algorithms
Medtronic
•Rate Drop response (RDR)
Boston
•Sudden brady response (SBR)
Microport
•Dplus mode
Biotronik
•Rate Fading
•Closed loop stimulation (CLS)
Abbott
•Advanced hysteresis
Any
•Hysteresis
Medtronic - rate drop response
Rate Drop Response (RDR) is intended to provide backup pacing and prevent associated symptoms in patients who experience occasional episodes of significant drop in heart rate (e.g., syncope from cardioinhibitory and mixed forms of carotid sinus syndrome)
There are two types of rate drop detection:
•Drop Detect occurs when there is a Sudden Rate Drop below the Drop Size and inside the Detection Window
•Low Rate Detect occurs when there is a Sudden Rate Drop to the lower rate.
Drop detect
Drop Detect occurs when there is a Sudden Rate Drop below the Drop Size &inside the Detection Window
Low rate detect
Low Rate Detect occurs when there is a Sudden Rate Drop to the lower rate.
Medtronic programming
Accessed from parameters; additional features; Rate therapies
•Detection Type: low rate, drop, both, off
•Intervention Rate: 60, 70, 75, ...100, ...180 bpm (not 65 or 85 (magnet rates)
•Intervention Duration: 1, 2, 3, ...15 minutes
•(LR)Detection beats: 1, 2, 3 beats
•(D)Drop Rate: 30, 40, 50, ...100 bpm
•(D)Drop Size: 10, 15, 20, 25, ...50 bpm
•(D)Detection Window: 10, 15, 20, 25, ...30 s; 1, 1.5, 2, 2.5 minutes
Boston - Sudden brady response
SBR is designed to respond to sudden decreases in intrinsic atrial rates by applying dual-chamber pacing at an elevated rate (DDD(R) modes).
SBR is declared when the atrial chamber has been continuously sensed for a programmable time, followed by a sudden decrease in atrial rate such that atrial pacing occurs at the lower rate limit or the sensor indicated rate for a programmable number of cycles.
The decrease in atrial rate preceding the paced events must exceed 10 bpm.
The SBR algorithm continually monitors the average of the atrial rate and this average is updated each cardiac cycle.
SBR Detect Time: the programmable time interval during which the atrium must be 100% sensed.
SBR Number of Beats: criteria are applied once the decrease in atrial rate has been detected and pacing occurs (either LRL or sensor indicated rate).
Atrial pacing must occur for the programmable number of consecutive intervals before the SBR criteria are met.
SBR Therapy Rate Offset: calculated by using the patients average atrial rate before the bradycardia and adding a programmable positive offset.
SBR therapy duration: is the programmable time interval during which SBR pacing therapy will be used.
Once pacing therapy has been delivered, the atrial pacing rate will be decreased using a 12% rate smoothing down factor until the lower rate or sensor indicated rate is reached.
Boston Programming
Accessed from brady parameters; rate enhancements
•Sudden Brady Response: off, on
•SBR Detect Time: 1-5 minutes (1 min increments) (5 min)
•SBR number of beats: 1-8 cycles (1 increments) (4 cycles)
•SBR therapy rate offset: 5-40 bpm (5 bpm increments) (5 bpm)
•SBR therapy duration: 1-15 minutes (1 min increments) (10 mins)
Microport D Plus mode
Dplus is an automatic AV delay histeresis algorithm that extends the AV delay (pseudo AAI) to encourage intrinsic rhythm but shortens the AV delay when AV delay worsens (DDD).
A switch fom DDD to pseudo AAI occurs after 8 consecutive cycles of AV conduction
Accessed from basic parameters; mode
•Mode: Dplus, Dplus-R, Dplus/DDIR
•Activation of Dplus results is automatic AV delay calculation
DPlus pacing mode with acceleration algorithm
•in order to access to acceleration function, program rate hysteresis with a value differnt from 0%
DPlus pacing mode with AV delay shortening
•in order to access AV delay shortening function, program acceleration with a value different from 0%
Biotronik - Rate fading
Prevent a sudden drop in heart rate when the pulse generator detects an abrupt decrease in the intrinsic rate.
Rate fading can be used to prevent potential reactions such as dizziness, light headedness, lack of energy and fainting.
Calculates the fading rate, which is a 4 beat average of the intrinsic rate reduced by 10 ppm.
When the intrinsic rate drops considerably (below the fading rate), the pacing rate begins at the rate fading rate and then decreases gradually by the programmable decay rate to the sensor or base rate.
•Rate increase: the maximum rate of change in the pacing rate if the sensor signal indicates increasing exertion.
•Rate decrease: the maximum rate of change in the pacing rate if the sensor signal indicates decreasing exertion.
Biotronik programming
Accessed from bradycardia; sensor/rate fading
•Rate Fading: off, on
•Rate Increase: 1-10 bpm (1 bpm increments) (4)
•Rate decrease: 0.1, 0.2, 0.5, 1.0 bpm
Hysteresis
Hysteresis may be set up in a way to mimic behavior of rate drop algorithms
This can be done by programming a
•high base rate, e.g., 100 ppm
•with a low hysteresis rate e.g., 50 ppm
Therefore, when the sensed rate drops to the hysteresis rate, fast pacing at the lower rate will occur
Abbott - advanced hysteresis
Advanced hysteresis may be set up in a way to mimic behavior of rate drop algorithms using the hysteresis rate as the drop rate, and an intervention rate with intervention duration and recovery time to aid the process.
Abbott programming
Accessed from bradycardia; rate/timing
•Hysteresis rate (bpm): off; 30-150 in steps of 5
•Cycle Count: 1-16 (in steps of 1)
•Intervention rate (bpm): off, 80-120 in steps of 10; intrinsic +0, intrinsic +10; intrinsic +20; intrinsic +30; same as base rate
•Intervention duration (bpm): 1-10 bpm (1 bpm increments)
•Recovery time: fast; medium; slow; very slow
Limitations of rate drop algorithms
The drop in the heart rate response for a vasovagal episode occurs in the 3rd stage of the episode and usually when the blood pressure response has already begun to dip.
Thus having algorithms that respond to the change in heart rate may not be effective in preventing the episode of syncope.
CLS measures the intracardiac impedance throughout EACH ventricular contraction.
During the “resting state” (monitored by accelerometer) the impedance values will establish a continuously updated reference curve, which reflects the contraction dynamics at rest.
Biotronik - Programming
