Transcript Document

Upper Rate Behavior
Why do we have Upper Rate Responses?
Reduce incidence of tracking inappropriate
rhythm and/or rate
for internal use only
Upper Rate Response Initiating Factors
Exercise
Sinus Tachycardia
Atrial Arrhythmia
Sensing of Myopotentials
VA conduction exceeding PVARP
for internal use only
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)
for internal use only
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.
for internal use only
DDD Timing
AVI
PV
PVARP
Atrial Channel
PVAB
Ventricular Channel
BL
VRP
URI
for internal use only
Max Track Rate
• The fastest rate the Ventricular channel can
pace when tracking intrinsic P-waves.
for internal use only
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
for internal use only
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?
for internal use only
Upper Rate Behaviors
Fixed-Ratio block/Multiblock (2:1, 3:1, etc)
Wenckebach behavior (Pseudo, Electronic)
Auto Mode Switch (not in this presentation)
for internal use only
Upper Rate Behaviors
Depends on programmed values:
• Max Tracking Rate
• Sensed AV Delay
• PVARP
for internal use only
Upper Rate Behavior
Fixed Ratio Block
Fixed-Ratio Block (Multiblock)
Fast Upper Rate Response
Simplest way to control upper rate
• TARP = MTR
AV
PVARP
TARP (Total Atrial Refractory Period)
for internal use only
Fixed-Ratio Block
2:1 Block (one v-paced event per two p-waves)
MTR = 115bpm AVD = 160ms PVARP = 360 ms
for internal use only
Fixed-Ratio Block
Calculation
• 60,000 / TARP: e.g. 60,000 / 440 ms
(2:1 block point)
= 136 BPM
PV
PVARP
160 ms + 280 ms
TARP = 440 ms
for internal use only
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
for internal use only
Fixed-Ratio Block
Fall Down Rate
for internal use only
2:1 blocking
Stimulated
ventricular rate
Ex.: Shipped Settings
PV Delay 150 ms
PVARP 275 ms
2:1-blockpoint
142 min-1
160
140
120
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
Upper Rate Responses
Wenckebach
Upper Rate Behavior
Wenckebach block
Do you remember?
AV Block 2nd degree Mobitz I
for internal use only
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
for internal use only
Wenckebach
Ap
Vp
Ap
Vp
Vp
P
P
P
P
Base Rate Interval
AV
AV
PV
V-A Interval
PVARP
MTR
TARP
W-Period
for internal use only
Wenckebach behaviour
Look at the VV and AV intervals
for internal use only
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
for internal use only
Wenckebach
Wenckebach response to increasing Atrial rates
Wenckebach
Plateau
Ventricular
Rate
(paced)
2:1
Lower
Rate
MTR
Atrial Rate (sensed)
for internal use only
3:1
1:1
TARP
..
.....
ARRP
Wenckebach
Example
• DDD
• MTR
100 bpm (600 ms)
• AV delay
150 ms
• PVARP
250 ms
• TARP150 + 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
for internal use only
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
for internal use only
Atrial Rate Continuum
Base Rate
MTR
AV delay
PVARP
60
130
170
250
PPM
PPM
MS
MS
60 PPM
Base Rate
Device
Response
130 PPM
(MTR)
1:1 Tracking
143 PPM
TARP
Wenckebach
TARP = PV Delay + PVARP
= 170 + 250
= 420 ms
143 PPM (2:1 Block Point)
for internal use only
2:1 Block
Wenckebach
Ap
Vp
Ap
Vp
Vp
P
P
P
P
Base Rate Interval
AV
AV
PV
150 ms
V-A Interval
PVARP
MTR
600 ms
TARP
W-Period
for internal use only
200 ms
Pseudo Wenckebach - Upper Rate Behaviour
A-A
AV Delay
PVARP
VRP
MTRI
Maximum Tracking Rate Interval
for internal use only
Wenckebach
Base Rate
MTR
AV
PV
Min. PV
PVARP
for internal use only
60 ppm
120 ppm
200 ms
150 ms
88 ms
250 ms
Wenckebach
P-wave in alert and sensed
AVPVARP
PVARP
MTR
MTR
PVARP
MTR
PVARP
MTR
PVARP
MTR
PVARP
MTR
PVARP
MTR
AV PVARP
MTR
PVARP
PVARP
MTR
Ventricular pacing at Max Tracking Rate
Base Rate
MTR
AV
PV
Min. PV
PVARP
for internal use only
60 ppm
120 ppm
200 ms
150 ms
88 ms
250 ms
MTR
AV PVARP
MTR
PVARP
MTR
AV PVARP
Wenckebach
Identification
• Variable PV delays
• Sustained high rate pacing
• Occasional change in the beat to beat
ventricular rate
• Long PV intervals may initiate an endlessloop Tachycardia
for internal use only
Wenckebach and MTR
Stimulated
ventricular rate
160
140
TARP
120
= Max. Tracking Rate
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
Upper Rate Responses
Fixed-ratio
Block
Wenckebach
PV Delay
constant
AV Delay progressively lengthens
Pauses in pacing operation may be seen
for internal use only
AMS
AV Delay
constant
until DDI(R)
pacing
occurs at
the AMS
base rate
2:1 blocking
Stimulated
ventricular rate
Ex.: Shipped Settings
PV Delay 150 ms
PVARP 275 ms
2:1-blockpoint
142 min-1
160
140
120
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
Factors Limiting Upper Rate
P
V
PV Delay
Programmed PV Delay
Rate Resp. AV/PV Delay
Shortest AV/PV Delay
for internal use only
PVARP
Programmed PVARP
Rate Resp. PVARP/VRP
Shortest PVARP/VRP
Rate Responsive AV Delay
To mimic normal heart function
70 min-1
Spontaneous
PR interval
reduction
Tracking
with RRAVD
enabled
for internal use only
110 min-1
130 min-1
Rate Responsive AV/PV Delays and Shortest AV/PV
Delay
200
150
100
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
95
0
90
50
Rate Responsive AV/PV Delays…
… and Shortest AV/PV Delay
200
150
100
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
195
190
185
180
175
170
165
160
155
150
145
140
135
130
125
120
115
110
105
100
95
0
90
50
2:1 blocking and RRAVD
Stimulated
ventricular rate
Ex.: Shipped Settings
PV Delay 150 ms
PVARP 275 ms
With RRAVD
160
140
120
(Low, Medium and High)
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
Rate Responsive Refractory Periods
PVARP
VRP
Low, 1 ms min-1
Medium, 2 ms min-1
High, 3 ms min-1
for internal use only
Pseudo Wenckebach Upper Rate Behaviour
MTR Intervall
for internal use only
MTR Intervall MTR Intervall
MTR Intervall
2:1 blocking and MTR
Stimulated
ventricular rate
160
140
= Max. Tracking Rate
Programmed MTR,
too high. Will not
limit the rate fall
at 2:1 block rate.
120
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
2:1 blocking
Stimulated
ventricular rate
160
140
= Max. Tracking Rate
= Max. Sensor Rate
120
= Sensor Indicated Rate
Use of a well tailored
sensor will relieve
the problems of a
high MTR
100
80
60
Sensed
Atrial Rate
80
for internal use only
100
120
140
160
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
for internal use only
Summary
When programming
• AV delay
• PVARP
• Max Tracking Rate
Remember
• Wenckebach
AVD + PVARP < MTR
• 2/1 block (mentioned on Merlin)
AVD + PVARP = MTR
for internal use only
Merlin
for internal use only
Upper Rate Behavior
Questions