Upper Rate Behavior. for internal use only Why do we have Upper Rate Responses? Reduce incidence of tracking inappropriate rhythm and/or rate

Upper Rate Behavior

for internal use only

Why do we have Upper Rate Responses?

Reduce incidence of tracking inappropriate rhythm and/or rate


Upper Rate Response Initiating Factors

Exercise

Sinus Tachycardia

Atrial Arrhythmia

Sensing of Myopotentials

VA conduction exceeding PVARP


Upper Rate Response Limit

Fastest Atrial rate at which consecutively paced ventricular complexes maintain 1:1 synchrony

• Also known as:• Ventricular Maximum Rate (VMR)• Maximum Tracking Rate (MTR)


Max Track Rate / Max Sensor Rate

Definitions

• The Max Track Rate, or Maximum Tracking Rate, is the fastest rate that intrinsic P-waves can be tracked, or followed by paced Ventricular events with a 1:1 ratio.

• The Max Sensor Rate, is the fastest rate the atria and the Ventricles can be paced, based upon sensor input.


DDD Timing

URI

AVI PVAVI PVARP

VRPBL

PVAB

Atrial Channel

Ventricular Channel


Max Track Rate

• The fastest rate the Ventricular channel can pace when tracking intrinsic P-waves.


Max Track Rate

Programmed settings should be based on

• Patient activity levels

• Age (220 – age)

• LV function

• Chest pain

• Tolerance by the Patient if a PMT occurs


Max Track Rate

Questions to consider

• Can the programmed Max Track Rate be tolerated by the patient for prolonged periods?

• During sinus tachycardia, can a sudden drop in the pacing rate be tolerated?


Upper Rate Behaviors

Fixed-Ratio block/Multiblock (2:1, 3:1, etc)

Wenckebach behavior (Pseudo, Electronic)

Auto Mode Switch (not in this presentation)


Upper Rate Behaviors

Depends on programmed values:

• Max Tracking Rate

• Sensed AV Delay

• PVARP

Upper Rate Behavior

Fixed Ratio Block


AV PVARP

TARP (Total Atrial Refractory Period)

Fixed-Ratio Block (Multiblock)

Fast Upper Rate Response

Simplest way to control upper rate

• TARP = MTR


Fixed-Ratio Block

2:1 Block (one v-paced event per two p-waves)

MTR = 115bpm AVD = 160ms PVARP = 360 ms


PV PVARP

TARP = 440 ms

160 ms + 280 ms

(2:1 block point)

Fixed-Ratio Block

Calculation

• 60,000 / TARP: e.g. 60,000 / 440 ms = 136 BPM


Fixed-Ratio Block

PV interval always remains constant

May be inappropriate in young or physically active patients due to sudden rate drops

Patient tracks P-waves until the atrial rate gets to the 2:1 block

• The Ventricular rate will suddenly go to half the Atrial rate


Fixed-Ratio Block

Fall Down Rate


Atrial

rate

160

140

120

100

14012010080

Stimulatedventricular rate

Sensed Atrial Rate

Ex.: Shipped SettingsPV Delay 150 msPVARP 275 ms2:1-blockpoint 142 min-1

80

60

160

2:1 blocking

Upper Rate Responses

Wenckebach

Upper Rate Behavior

Wenckebach block


Do you remember?

AV Block 2nd degree Mobitz I


Wenckebach

Max Track (MTR) must be programmed slower than the TARP interval

2:1 fixed-ratio block will occur when the P-P intervals become faster than TARP


V-A Interval

Base Rate Interval

MTR

PVARP

PV

W-Period

P

P

P

TARP

Wenckebach

P

Ap Vp Ap Vp Vp

AVAV


Wenckebach behaviour

Look at the VV and AV intervals


Wenckebach

Provides a smoother transition from 1:1 to 2:1 block

Avoids a sudden reduction of the ventricular pacing rate and maintains some degree of AV synchrony


Ventricular Rate (paced)

LowerRate

1:1

Wenckebach Plateau

2:1

3:1

. . . ...

.

Atrial Rate (sensed)

MTR TARP ARRP

Wenckebach

Wenckebach response to increasing Atrial rates


Wenckebach

Example• DDD

• MTR 100 bpm (600 ms)

• AV delay 150 ms

• PVARP 250 ms

• TARP 150 + 250 = 400 ms \150ppm

• Therefore, atrial rates >100 bpm (600 ms) but < 150 bpm will result in Wenckebach behavior

• Max PV delay prolongation is 200 ms (600-400)• PV intervals will vary from 150 - 350 ms


Wenckebach

Calculation to determine if a Wenckebach is present:

• Programmed MTR minus TARP

• In our example: 600 ms - 400 ms = 200 ms

• We have a 200 ms Wenckebach window


60 PPM 130 PPM 143 PPM

Base Rate 60 PPMMTR 130 PPMAV delay 170 MSPVARP 250 MS

TARP = PV Delay + PVARP= 170 + 250= 420 ms 143 PPM (2:1 Block Point)

Atrial Rate Continuum

Base Rate (MTR) TARP

DeviceResponse

1:1 Tracking Wenckebach 2:1 Block


Wenckebach

V-A Interval

Base Rate Interval

MTR

PVARP

PV

W-Period

P

P

P

TARP

P

Ap Vp Ap Vp Vp

AVAV 150 ms

200 ms

600 ms


Maximum Tracking Rate Interval

A-A

PVARP

VRP

MTRI

AV Delay

Pseudo Wenckebach - Upper Rate Behaviour


Wenckebach

Base Rate 60 ppmMTR 120 ppmAV 200 msPV 150 msMin. PV 88 msPVARP 250 ms


Wenckebach

AV PVARP

MTR MTR MTR MTR MTR MTR MTR MTR MTR MTR MTR MTR

AV AV AVPVARP PVARP PVARP PVARP PVARP PVARP PVARP PVARP PVARP PVARP PVARP PVARP

P-wave in alert and sensed

Ventricular pacing at Max Tracking Rate

Base Rate 60 ppmMTR 120 ppmAV 200 msPV 150 msMin. PV 88 msPVARP 250 ms


Wenckebach

Identification

• Variable PV delays

• Sustained high rate pacing

• Occasional change in the beat to beat ventricular rate

• Long PV intervals may initiate an endless-loop Tachycardia


Atrial

rate

160

140

120

100

14012010080


Sensed Atrial Rate

80

60

160

Wenckebach and MTR

= Max. Tracking Rate

TARP


WenckebachFixed-ratioBlock

AMS

AV Delay progressively lengthens

Pauses in pacing operation may be seen

PV Delay constant

AV Delayconstant

until DDI(R)pacing

occurs atthe AMS base rate

Upper Rate Responses


Atrial

rate

160

140

120

100

14012010080


Sensed Atrial Rate

Ex.: Shipped SettingsPV Delay 150 msPVARP 275 ms2:1-blockpoint 142 min-1

80

60

160

2:1 blocking


P V

Factors Limiting Upper Rate

PVARPPV Delay

Programmed PV DelayRate Resp. AV/PV DelayShortest AV/PV Delay

Programmed PVARPRate Resp. PVARP/VRPShortest PVARP/VRP


To mimic normal heart function

SpontaneousPR intervalreduction

70 min-1 130 min-1110 min-1

Tracking with RRAVDenabled

Rate Responsive AV Delay


Rate Responsive AV/PV Delays and Shortest AV/PV Delay

0

50

100

150

90

95

10

0

11

0

10

5

11

5

12

0

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5

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0

14

5

15

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0

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5

18

0

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5

19

0

19

5

Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1

200


Rate Responsive AV/PV Delays… … and Shortest AV/PV Delay

0

50

100

150

90

95

10

0

11

0

10

5

11

5

12

0

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0

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0

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0

19

5

Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1

200


Atrial

rate

160

140

120

100

14012010080


Sensed Atrial Rate

80

60

160

2:1 blocking and RRAVD

Ex.: Shipped SettingsPV Delay 150 msPVARP 275 msWith RRAVD(Low, Medium and High)


PVARP

VRP

Rate Responsive Refractory Periods

Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1


PVARP

VRP


Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1


PVARP

VRP


Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1


PVARP

VRP


Low, 1 ms min-1

Medium, 2 ms min-1

High, 3 ms min-1


MTR Intervall MTR Intervall MTR Intervall MTR Intervall

Pseudo Wenckebach Upper Rate Behaviour


Atrial

rate

160

140

120

100

14012010080


Sensed Atrial Rate

Programmed MTR, too high. Will not limit the rate fall at 2:1 block rate.

80

60

160

2:1 blocking and MTR



Atrial

rate

160

140

120

100

14012010080


Sensed Atrial Rate

Use of a well tailoredsensor will relieve the problems of a high MTR

80

60

160

2:1 blocking


= Max. Sensor Rate

= Sensor Indicated Rate


Summary

One to One tracking is the best upper rate behavior

When tracking at this rate is inappropriate, the device may be programmed to exhibit:

• Fixed Ratio Block (Multiblock)

• Wenckebach

• RR AV delay – PVARP/VRP

• DDIR

• Auto Mode Switch


Summary

When programming

• AV delay

• PVARP

• Max Tracking Rate

Remember

• WenckebachAVD + PVARP < MTR

• 2/1 block (mentioned on Merlin)AVD + PVARP = MTR


Merlin

Upper Rate Behavior

Questions

Documents

Upper Rate Behavior. for internal use only Why do we have Upper Rate Responses? Reduce incidence of tracking inappropriate rhythm and/or rate