2. Dual-Chamber Timing
Göran Mathson, 2005

3. NASPE/BPEG Generic Pacemaker Code
What is
stimulated? I
0=None
A=Atrium V=Ventricle D=Dual (A+V)
S=Single
(A or V)
What is
sensed? II
0=None
A=Atrium V=Ventricle D=Dual (A+V)
S=Single
(A or V)
Reaction to
sensing
III
0=None T=Triggered I=Inhibited D=Dual (T+I)
Rate Modulation IV
0=None R=Rate Modulation
Multisite Pacing V
0=None
A=Atrium V=Ventricle D=Dual (A+V)
The Revised NASPE/BPEG Generic Code for
Antibradycardia, Adaptive-Rate, and Multisite
Pacing,
PACE , Volume 25, No. 2, February 2002

4. Pacing systems AAI(R) VVI(R) DDD(R) VDD(R) = Sensing point
= Stimulation point
= Sensing and Stimulation point

5. A-A
This presentation is on atrial-based DDD timing. This is the timing system we have had since Affinity. Main timer is the A-A timer, generally corresponding to the basic rate. The timer starts with an atrial event whether paced or sensed. And if it times out, you will see an atrial stimulus on the ECG.

6. A-A
AV Delay
In parallell to the A-A timer, AV delay runs. Starting with an paced atrial event. And if it times out, you will see an ventricular stimulus on the ECG.

7. A-A
PV Delay
PV delay is like the AV delay but the starting point is the sensing of a P-wave.

8. AV and PV Delay...
To make haemodynamics equivalent whether the atrium is paced or sensed, the AV and PV delays are separately programmable. Per definition an AV delay starts the atrial depolarisation and the PV delay detects an already ongoing depolarisation. Hence, to get the same haemodynamics, PV delay is usually programmed slightly shorter than the AV delay.
170 ms
150 ms

9. AV and PV interval... Late atrial activation
In some cases, the atrial lead sits in a slow conducting part of the atrium, resulting in late atrial activation. To some extent, you can limit the haemodynamic consequences by programming AV and PV delays differently.
250 ms
150 ms
The AV Delay can be programmed max. 100 ms longer than the PV Delay

10. Late Atrial Activation
In this case: AV Delay should be 80 ms longer than PV Delay

11. A-A
AV Delay
Both the AV and PV delay can be terminated by sensing of a ventricular event.

12. A-A terminated by intrinsic P-wave
AV Delay
The A-A timer can be terminated by sensing of an atrial event, restarting a new A-A timer and a PV delay.
A-A terminated by intrinsic P-wave

13. A-A – AV delay timer starts on detection of a PVC
A-A terminated by a PVC
A-A – AV delay timer starts
on detection of a PVC
The A-A timer can also be terminated by a ventricular event. Per definition this would now be a PVC. This ventricular event restarts a modified A to A timer. It is reduced by the AV delay to avoid an extra long pause until the next ventricular paced event.

14. Post Ventricular Atrial Refractory Period
A-A
AV Delay
PVARP
Post Ventricular Atrial Refractory Period
Programmable refractory period on the atrial channel is called PVARP. It starts with a ventricular event paced or sensed.

15. AV/PV Delay + PVARP = Total Atrial Refractory Period, TARP
A-A
AV Delay
PVARP
In fact, the atrial channel is refractory also during the AV/PV delay. TARP is not directly programmable, but will play a significant role in upper rate behaviour.
AV/PV Delay + PVARP = Total Atrial Refractory Period, TARP

16. Example of programmability...
25,
30, 40, 50…170…350
150
200
250
300
350
400
450
500
175
225
275
325
375
425
475

17. Noise Mode, Atrial Channel
PVARP
The main refractory periods, in this case PVARP, consists of two parts, one absolute refractory and one relative refractory part. Noise mode appears when signals of a very high rate are picked up in the relative refractory period. The refractory period will be prolonged as long as these high rate signals keep coming in. The effect of this is basic rate pacing.
A-A Interval
Absolute
Relative
Programmable PVARP

18. Noise sampling window (NSW)
Sensed Event
NSW 150 ms
Example Identity ADx:
100 ms
175 ms
Relative
Absolute
Sensed Event
NSW 150 ms
Sensed Event
NSW 150 ms
Sensed Event
Sensed Event

19. Noise Mode, Atrial Channel
A-A Interval

20. Ventricular Refractory Period
A-A
AV Delay
PVARP
VRP
The ventricular refractory period starts with a ventricular event, paced or sensed.
Ventricular Refractory Period

21. Ventricular Blanking Period
A-A
AV Delay
PVARP
VRP
Ventricular blanking period appears on the ventricular channel after atrial stimulation only. Reason for this is to avoid cross talk, see next slide.
Ventricular Blanking Period

22. Far-field sensing Crosstalk Intrinsic activity is sensed in the
= Sensing point
= Stimulation point
= Sensing and Stimulation point
Far-field sensing
Intrinsic activity
is sensed in the
“wrong” chamber
Crosstalk
Pacemaker activity is
sensed in the “wrong” chamber
Note that cross talk can only appear on the ventricular channel. The atrial channel would be in PVARP when the ventricular stimulation appears.

23. Example of programmability...
12…51ms
125
175
225
275
325
375
425
475
150
200
250
300
350
400
450

24. Maximum Tracking Rate Interval
A-A
AV Delay
PVARP
VRP
Maximum tracking rate interval corresponds to the programmed maximum tracking rate. It starts with a ventricular event, paced or sensed.
MTRI
Maximum Tracking Rate Interval

25. A-A
AV Delay
PVARP
VRP
MTRI
Maximum Tracking Rate Interval

26. Pseudo Wenckebach Upper Rate Behaviour
MTR Interval
MTR Interval
MTR Interval
MTR Interval

27. A-A AV Delay PVARP VRP MTRI MSRI
Maximum sensor rate interval corresponds to the programmed maximum sensor rate. (Since this is an atrial based timing, it starts with the atrial event paced or sensed.)
MTRI
MSRI

28. V = Ventricular paced event R = Ventricular sensed event
Markers…
A = Atrial paced event
P = Atrial sensed event
V = Ventricular paced event
R = Ventricular sensed event

29. DDD(R) Pacing States
AV-Pacing
AR-Pacing
PV-Pacing
PR-Pacing

30. DDD(R) Pacing States AV-Pacing
AV pacing appears at basic rate or in a rate modulated system at sensor driven rate. In today’s devices, there are many more possibilities as well, for instance, AF suppression or rest rate.

31. DDD(R) Pacing States PV-Pacing
P-wave tracking. This would be the typical pacing state of an AV block patient.

32. DDD(R) Pacing States
PR-Pacing

33. DDD(R) Pacing States AR-Pacing
Atrial stimulation with intrinsic conduction. This would be the typical pacing state of an Sinus Node Disease patient.

34. Pacing States A V A R P V P R
It might facilitate interpretation to make the annotations on a Xerox copy…

35. Markers P R A V P R Atrial Refractory period
142
546
694
170
617
759
Atrial Refractory period P R
Ventricular Refractory period

36. DDI Timing
DDI(R) is active during mode switch… 2

37. NASPE/BPEG Generic Pacemaker Code
What is
stimulated? I
0=None
A=Atrium V=Ventricle D=Dual (A+V)
S=Single
(A or V)
What is
sensed? II
0=None
A=Atrium V=Ventricle D=Dual (A+V)
S=Single
(A or V)
Reaction to
sensing
III
0=None T=Triggered I=Inhibited D=Dual (T+I)
Rate Modulation IV
0=None R=Rate Modulation
Multisite Pacing V
0=None
A=Atrium V=Ventricle D=Dual (A+V)
The Revised NASPE/BPEG Generic Code for
Antibradycardia, Adaptive-Rate, and Multisite
Pacing,
PACE , Volume 25, No. 2, February 2002

38. AVI AEI VEI PVARP VRP MSRI
DDI could be programmed or appear as the mode during mode switch. DDI has ventricular based timing. At the ventricular event, both an atrial escape interval and a ventricular escape interval starts.
VRP
MSRI

39. AVI AEI VEI PVARP VRP MSRI
If a high atrial rate is detected, the ventricular rate will not be affected.
VRP
MSRI

40. P V
AVI
AEI
VEI
PVARP
VRP
MSRI

41. AVI
AEI
VEI
PVARP
VRP
MSRI

42. Lower Rate 2

43. Rest Rate, and it’s Sensor Driven!
Basic Rate
Rest Rate is sensor driven – patients can rest when they feel like it.
It is technically based on statistics long term (Activity Variance Histogram) compared to short time.
Rest Rate

44. Rate Hysteresis Classic single-chamber version Basic Rate
Hysteresis Rate
Classical single-chamber rate hysteresis. Today almost exclusively used in VVI(R) in conjunction with Autocapture. This is to avoid a series of (pseudo)fusion beats.

45. Advanced Hysteresis Response
Intervention Duration
Sensor
Recovery
Rate
Search Interval
Intervention- rate
Basic rate
Hysteresis rate
Advanced hysteresis response is mainly used together with DDI mode in patients with vasovagal syncope.
Cycle Count
Cycle Count

46. Crosstalk…
A V
P V A R
Crosstalk events marked by the arrows.

47. Decrease atrial output? Decrease ventricular sensitivity?
Crosstalk
Decrease atrial output?
Decrease ventricular sensitivity?
Prolong ventricular blanking?
Enable Ventricular Safety Standby!
The classical recommendations to avoid crosstalk. They are not easy to follow, except for the use of Ventricular Safety Standby.

48. Ventricular Safety Standby
Blanking Period
Crosstalk Detection Window

49. Ventricular Safety Standby
Crosstalk V. Safety Pacing after 120 ms

50. Is Ventricular Safety Pacing Present In This Panel?
Yes, in the last event! But it is due to a late cycle PVC (no crosstalk).

51. Vetricular Safety Pacing
Other tracing – same story.

52. Ventricular Safety Standby
Sensing in Crosstalk Detection Window
V. Safety Pacing after 120 ms

53. Ventricular Safety Standby
Blanking Period Undersensing V. Pacing after programmed AV Interval
We can enjoy the shortest Ventr. Blanking in the industry. This is important – look at the next slide!

54. Blanking period undersensing can be dangerous at long AV intervals
Blanking period under-sensing can be dangerous if AV delay is programmed long. Note that this will happen with AutoCapture as well when the backup pulse will come approximately 100 milliseconds after the initial stimulus. AICS can also produce a dangerous situation. This can be the case in competitors devices as well, of course. Again, we have the shortest ventr. Blanking!
Conclusion, it is preferable to have a very short blanking period if possible.
Blanking period undersensing can be dangerous at long AV intervals

55. AutoIntrinsic Conduction Search Neg. AV/PV Hysteresis AF Suppression
Special Features
AutoIntrinsic Conduction Search
Neg. AV/PV Hysteresis
AF Suppression

56. AutoIntrinsic Conduction Search
Programming Suggestions

57. AutoIntrinsic Conduction Search in Intermittent High Degree AV-BlockP V
150
788
938
Programme the optimal AV/PV Delay for time in high degree AV-block 1
Add an AutoIntrinsic Conduction Search of e.g ms to allow for intrinsic conduction within a hemodynamically acceptable
conduction time 2
Philosophy: High degree AV block will need relatively high percentage ventricular stimulation. Hemodynamically optimized AV delay is important.
150
Progr.
PV Interval
100
AICS

58. AutoIntrinsic Conduction Search in Intermittent High Degree AV-BlockP
232 R
The pacemaker will now allow
for intrinsic conduction within
the prolonged AV/PV Delay,
in this case 250 ms.
634
812
150
Progr.
PV Interval
100
AICS

59. AutoIntrinsic Conduction Search in Intermittent High Degree AV-Blockms ms ms
150 ms
150 ms
Programmed AV/PV Delay
AutoIntrinsic Conduction Search

60. AutoIntrinsic Conduction Search in Intermittent High Degree AV-Block
150 ms
Search ms ms ms
150 ms
Programmed AV/PV Delay
AutoIntrinsic Conduction Search

61. AutoIntrinsic Conduction Search in Sinus Node DiseaseP R
171
767
938
Let the pacemaker measure the PR- and AR-Interval at rest 1
Program PV- and AV Delay
slightly longer than
intrinsic conduction 2
Add an AutoIntrinsic Conduction Search of 120 ms 3
Philosophy: SND will need low percentage, if any, ventricular stimulation. Avoiding un-necessary ventricular stimulation is in focus.
200
Programmed
PV Interval
120
AICS

62. AutoIntrinsic Conduction Search in Sinus Node DiseaseP
268 R
The pacemaker will now allow
for intrinsic conduction within
the prolonged AV/PV Delay,
in this case 320 ms.
670
841
200
Programmed
PV Interval
120
AICS

63. AutoIntrinsic Conduction Search in Sinus Node Disease
Preference of intrinsic conduction... ms ms ms ms ms
Programmed AV/PV Delay
AutoIntrinsic Conduction Search

64. AutoIntrinsic Conduction Search in Sinus Node Disease
Back-up pacing if, against all odds, intrinsic conduction is lost... ms
200 ms
200 ms
200 ms
200 ms
Programmed AV/PV Delay
AutoIntrinsic Conduction Search

65. Neg. AV/PV Hysteresis
Programming in HOCM

66. HOCM
Hypertrophic Obstructive CardioMyopathy

67. Negative AV/PV-hysteresis
Measure, with the puls generator, the PR interval
Program, with the aid of Echo, the optimal PV- Delay. (Longest PV Delay with full capture)
To make this dynamic, program how much faster pacing should be, compared to a sensed R-wave (PRMeas – PVOpt). This is called Neg. AV/PV Delta.

68. Negative AV/PV-Hysteresis
(search)
81 ms
74 ms
74 ms
124 ms
124 -
124 -
50 ms
50 ms
Measured PR-interval
Neg. AV/PV-Delta (Programmable, -10 to -110 ms)
Resulting PV-interval

69. AF Suppression

70. AF Suppression, AFx
> 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

71. AF Suppression, AFx MSR AFx Intrinsic Rate Basic Rate
Searches will happen approximately 2-3 times a minute.
Basic Rate

72. AF Suppression, AFx
AFx
Overdrive: 10 min-1 at rate 60 min-1 and 5 min-1 at rate 150 min-1.

73. AF Suppression, AFx Search for intrinsic activity 67 66 65
Activity found (two P-waves) 64 65
Increase stimulation rate 74
To apply overdrive, two P-waves has to be sensed, the second within 16 cycles from the first.

74. AF Suppression, AFx !
… and to programme:
ON / OFF