Upper Rate Behavior

1
Upper Rate Behavior
2
Why do we have Upper Rate Responses?

• Reduce incidence of tracking inappropriate rhythm
  and/or rate

3
Upper Rate Response Initiating Factors

• Exercise
• Sinus Tachycardia
• Atrial Arrhythmia
• Sensing of Myopotentials
• VA conduction exceeding PVARP

4
Upper Rate Response Limit

• Fastest Atrial rate at which consecutively paced
  ventricular complexes maintain 11 synchrony
• Also known as
• Ventricular Maximum Rate (VMR)
• Maximum Tracking Rate (MTR)

5
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 11 ratio.
• The Max Sensor Rate, is the fastest rate the
  atria and the Ventricles can be paced, based upon
  sensor input.

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DDD Timing
A
VI
PV
A
VI
PVARP
Atrial Channel
PVAB
VRP
BL
Ventricular Channel
URI
7
Max Track Rate

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

8
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

9
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?

10
Upper Rate Behaviors

• Fixed-Ratio block/Multiblock (21, 31, etc)
• Wenckebach behavior (Pseudo, Electronic)
• Auto Mode Switch (not in this presentation)

11
Upper Rate Behaviors

• Depends on programmed values
• Max Tracking Rate
• Sensed AV Delay
• PVARP

12
Upper Rate Behavior

• Fixed Ratio Block

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Fixed-Ratio Block (Multiblock)

• Fast Upper Rate Response
• Simplest way to control upper rate
• TARP MTR

14
Fixed-Ratio Block

• 21 Block (one v-paced event per two p-waves)

MTR 115bpm AVD 160ms PVARP 360 ms
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Fixed-Ratio Block

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

(21 block point)
160 ms 280 ms
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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 21 block
• The Ventricular rate will suddenly go to half the
  Atrial rate

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Fixed-Ratio Block
Fall Down Rate
18
21 blocking
Atrial rate
Stimulatedventricular rate
Ex. Shipped Settings PV Delay 150 ms PVARP 275
ms 21-blockpoint 142 min-1
160
140
120
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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Upper Rate Responses

• Wenckebach

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Upper Rate Behavior

• Wenckebach block

21
Do you remember?
AV Block 2nd degree Mobitz I
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Wenckebach

• Max Track (MTR) must be programmed slower than
  the TARP interval
• 21 fixed-ratio block will occur when the P-P
  intervals become faster than TARP

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Wenckebach
Base Rate Interval
PV
AV
AV
V-A Interval
PVARP
MTR
TARP
W-Period
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Wenckebach behaviour
Look at the VV and AV intervals
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Wenckebach

• Provides a smoother transition from 11 to 21
  block
• Avoids a sudden reduction of the ventricular
  pacing rate and maintains some degree of AV
  synchrony

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Wenckebach

• Wenckebach response to increasing Atrial rates

Wenckebach Plateau
31
Ventricular Rate (paced)
11
.
21
.
.
.
.
.
.
Lower Rate
MTR
TARP
ARRP
Atrial Rate (sensed)
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Wenckebach

• Example
• DDD
• MTR 100 bpm (600 ms)
• AV delay 150 ms
• PVARP 250 ms
• TARP 150 250 400 ms \150ppm
• Therefore, atrial rates gt100 bpm (600 ms) but lt
  150 bpm will result in Wenckebach behavior
• Max PV delay prolongation is 200 ms (600-400)
• PV intervals will vary from 150 - 350 ms

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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

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Atrial Rate Continuum
Base Rate 60 PPM MTR 130 PPM AV
delay 170 MS PVARP 250 MS
60 PPM
130 PPM
143 PPM
Base Rate
TARP
(MTR)
Device Response
11 Tracking
Wenckebach
21 Block
TARP PV Delay PVARP 170 250 420 ms 143
PPM (21 Block Point)
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Wenckebach
Base Rate Interval
150 ms
PV
AV
AV
V-A Interval
PVARP
600 ms
MTR
TARP
200 ms
W-Period
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Pseudo Wenckebach - Upper Rate Behaviour
A-A
AV Delay
PVARP
VRP
MTRI
Maximum Tracking Rate Interval
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Wenckebach
Base Rate 60 ppm MTR 120 ppm AV 200
ms PV 150 ms Min. PV 88 ms PVARP 250 ms
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Wenckebach
Base Rate 60 ppm MTR 120 ppm AV 200
ms PV 150 ms Min. PV 88 ms PVARP 250 ms
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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

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Wenckebach and MTR
Atrial rate
Stimulatedventricular rate
160
140
TARP
120
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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Upper Rate Responses
Wenckebach
Fixed-ratio Block
AMS
AV Delay constant until DDI(R) pacing occurs
at the AMS base rate
PV Delay constant
AV Delay progressively lengthens
Pauses in pacing operation may be seen
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21 blocking
Atrial rate
Stimulatedventricular rate
Ex. Shipped Settings PV Delay 150 ms PVARP 275
ms 21-blockpoint 142 min-1
160
140
120
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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Factors Limiting Upper Rate
P
V
Programmed PV Delay Rate Resp. AV/PV
Delay Shortest AV/PV Delay
Programmed PVARP Rate Resp. PVARP/VRP Shortest
PVARP/VRP
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Rate Responsive AV Delay
To mimic normal heart function
SpontaneousPR intervalreduction
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Rate Responsive AV/PV Delays and Shortest AV/PV
Delay
200
150
100
50
0
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
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Rate Responsive AV/PV Delays
and Shortest AV/PV Delay
200
150
100
50
0
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
42
21 blocking and RRAVD
Stimulatedventricular rate
Ex. Shipped Settings PV Delay 150 ms PVARP 275
ms With RRAVD(Low, Medium and High)
160
140
120
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
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Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
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Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
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Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
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Pseudo Wenckebach Upper Rate Behaviour
MTR Intervall
MTR Intervall
MTR Intervall
MTR Intervall
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21 blocking and MTR
Atrial rate
Stimulatedventricular rate
160
140
Programmed MTR, too high. Will not limit the
rate fall at 21 block rate.
120
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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21 blocking
Atrial rate
Stimulatedventricular rate
160
140
120
Use of a well tailored sensor will relieve the
problems of a high MTR
100
80
60
Sensed Atrial Rate
160
140
120
100
80
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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

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Summary

• When programming
• AV delay
• PVARP
• Max Tracking Rate
• Remember
• Wenckebach
• AVD PVARP lt MTR
• 2/1 block (mentioned on Merlin)
• AVD PVARP MTR

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Merlin
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Upper Rate Behavior

• Questions