af suppression algorithm overview for internal use only af suppression algorithm overview the goal...
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AF Suppression™
Algorithm Overview
for internal use only
AF Suppression™ Algorithm Overview
•The goal is to keep atrial arrhythmias from occurring
• Prevention of atrial fibrillation• A fib begets A fib!
•Solution: An algorithm designed to keep the atrial pacing rate just above the patient’s changing intrinsic atrial rate, resulting in constant atrial pacing
for internal use only
> 90% Atrial Pacing
AFx ensures a high percentage of atrial stimulation at a rate following the patients natural circadian variations, thereby maintaining control of the atrium, reducing ectopy, and suppressing atrial tachyarrhythmias
AF Suppression, AFx
for internal use only
MSR
Basic Rate
AFx
Intrinsic Rate
AF Suppression, AFx
for internal use only
AF Suppression, AFx
AFx
for internal use only
Search for intrinsic activity
67 66 65
Activity found(two P-waves)
64 65
Increase stimulation rate
74 74 7474
AF Suppression, AFx
ASAP AP ASAP APAP APVPVP VPVPVP VPVP VPVP
for internal use only
… and to programme:
ON / OFF !AF Suppression, AFx
for internal use only
AF Suppression™ Algorithm Overview
• Programmable: • ON• OFF (nominal)
• Screen: Parameters-Brady, AT/AF Detection & Response
• Only available in the following modes• DDD/R• AAI/R
for internal use only
AF Suppression™ Algorithm Overview
for internal use only
AF Suppression™ Algorithm Overview
for internal use only
AF Suppression™ Algorithm Overview
•When the algorithm is activated, the device looks for
• 2 P-waves within 16 cycles• Only P-waves in the alert period will be used
• If 2 P-waves within 16 cycles are seen, the device will increase the atrial pacing rate
for internal use only
AS AP AP AP AP AP AP AP AP AP AP AP AP AP AP AP AP0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Start 16-cycle counter
AS = P-waveAP = Atrial pacing
Only 1 P-wave was seen. Therefore, NO Overdrive occurs
End 16-cycle counter
Note: Notice how the algorithm starts with a “0” not a “1”
AF Suppression™ Algorithm Overview
for internal use only
AF Suppression™ Algorithm Overview
AS AP AP AP AP AP AP AP AP AP AP AP AP AP AP AS0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Start 16-cycle counter
2 P-waves were seen therefore, Overdrive occurs
Start Overdrive
AS = P-waveAP = Atrial pacing
for internal use only
AS AS
Overdrive Rate
Pacing Rate
2 P-waves were seen therefore, Overdrive occurs
AF Suppression™ Algorithm Overview
for internal use only
AF Suppression™ Algorithm Overview
• A look-up table within the device determines the Overdrive rate
• The current atrial pacing rate is used to determine the increase in atrial rate
• The Maximum AF Suppression rate is the maximum rate for atrial overdrive pacing when AF Suppression is programmed on
for internal use only
AF Suppression™ Algorithm Overview
• Once the atrial Overdrive rate is determined, the device will pace at this rate for a programmable number of cycles
• 15 (nominal), 20, 25, 30, 35 or 40 cycles
• When AF suppression is programmed ON, the Overdrive Pacing Cycles is the only programmable parameter
• Cycle count of 15 was programmed most often during the Adopt-A clinical trial
for internal use only
AF Suppression™ Algorithm Overview
• Once the number of Overdrive cycles has been completed the Rate Recovery phase will start
• If the Overdrive rate is 100 ppm - 12 ms will be added to each cycle, resulting in a lower rate
• If the Overdrive rate is >100 ppm - 8 ms will be added to each cycle, resulting in a lower rate
for internal use only
AS AS
Overdrive Rate
Pacing Rate
2 P-waves were seen therefore, Overdrive occurs followed by Rate Recovery
Pacing Rate
AF Suppression™ Algorithm Overview
Rate Recovery
for internal use only
AF Suppression™ Algorithm Overview
What if there are additional P-waves sensed during the Overdrive portion?
for internal use only
AF Suppression™ Algorithm Overview
• If 1 P-wave is sensed during the Overdrive portion, the 16 cycle counter will start
• If 2 P-waves are sensed within 16 cycles, the device will increase the atrial rate and Overdrive will start
for internal use only
AS AS
Overdrive Rate
Pacing Rate Pacing Rate
AS AS
Overdrive Rate
AF Suppression™ Algorithm Overview
Rate Recovery
for internal use only
AF Suppression™ Algorithm Overview
What if 1 P-wave is sensed in the Rate Recovery portion?
for internal use only
AF Suppression™ Algorithm Overview
• If 1 P-wave is sensed during the Rate Recovery portion, the 16 cycle counter will start
• If 2 P-waves are sensed within 16 cycles, the device will increase the atrial rate and Overdrive will start
for internal use only
AS AS
Overdrive Rate
Pacing Rate Pacing Rate
ASAS
Overdrive Rate
Rate Recovery
Rate Recovery
AF Suppression™ Algorithm Overview
