dr shreetal rajan nair senior resident, department of cardiology mch, calicut
TRANSCRIPT
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Upper rate behaviour in dual chamber pacemaker
Dr Shreetal Rajan NairSenior resident , Department of Cardiology
MCH, Calicut.
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DDD pacemaker- 4 rhythm scenarios
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Dual Chamber Timing Cycle
• Lower rate interval (LRI)• Upper rate interval (URI) – Maximum tracking rate (MTR)
– Maximum sensor rate • AV and VA interval• Refractory period• Blanking period
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Dual-chamber Timing Intervals
AV Interval
TARPVA Interval
LRI
A-BlankingPVARPV-Blanking
URI/MTR
VRP
Ap Vp Ap Vp Ap Vp
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Upper rate behavior refers to how a dual-chamber pacemaker will behave when the atrial rate exceeds the programmed maximum tracking rate
There are three types of upper rate behavior
1:1 Tracking
Pacemaker Wenckebach
2:1 Block
The key to upper rate behavior is in the atrium
Observed only when the device is tracking intrinsic P waves (A sense/V pace)
Upper rate behavior
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Normal 1:1 tracking
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Pacemaker Wenckebach (PSEUDOWENCKEBACH)
W
As Vp As Vp
MAXIMUM TRACKING RATE
TARP
PVARP
AV
TARP
PVARP
AV
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Upper Rate Pacing CharacteristicsWenckebach (4:3 Block)
As Vp As Vp As Vp (As) As Vp As Vp As Vp
TARP
AV Delay
VA Interval
MTR
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Upper Rate Pacing Characteristics
As Vp (As) As Vp As Vp As Vp(As) (As) (As)
TARPAV DelayVA Interval
MTRLRI
2:1 Block
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2:1 Block
AV
PVARP
TARP
MAXIMUM TRACKING RATE
AV
PVARP
TARP
As Vp (As) As Vp
2:1 Rate = 60,000 / TARP
Upper Rate Pacing Characteristics
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Upper Rate Pacing Characteristics
1:1
Wenckebach
2:1 BlockTARP
MTR
LRI
SinusRate
Upper Rate Behavior is determined by TARP and MTR
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How to deal with this?
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Solution In young patients, the upper rate of the
pacemaker to be programmed to faster rates corrected for the patient's age to prevent Wenckebach behavior of the pacemaker during exercise.
Programming dynamic AV interval and dynamic PVARP allows the TARP to be shorter at higher pacing rates and avoid sudden slowing of ventricular pacing rates.
Sensor driven pacing : a separately programmable sensor rate allows the pacemaker to continue to pace at the sensor-driven rate during exercise
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Dynamic AVI and PVARP
Programmed AV Delay shortens with increasing rate
Allows programming a higher MTR for higher 1:1 P-synchronous tracking
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Dynamic AVI and PVARP
AV Delay + PVARP = TARP
65 ms
300 ms 365 ms (164 ppm)
130 ms
300 ms 430 ms (139 ppm)
200 ms
300 ms 500 ms (120 ppm)
Effects of Shorter AV Delay
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Dynamic AVI and PVARP
Rate = 65 ppm AV Delay ~ 180 ms Rate to 135 ppm
AV Delay
~ 80ms
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Rate-responsive PacingSensor driven (DDDR) pacing promotes a
more regular rhythm if the sinus rate exceeds the MTR. It is not dependent on the PVARP
DDD - Wenckebach
DDDR
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Thank you