Transcript The Evolution of ICD Therapy:

Dual Chamber
Temporary Pacing
Operations & Troubleshooting
Indications for Dual Chamber
Temporary Pacing
 Complete heart block
 Sinus bradycardia
 Bradycardia with congestive heart failure
 Atrial and/or ventricular ectopic arrhythmia
 Reentrant tachycardias
 During pulse generator replacement
Indications for Dual Chamber
Temporary Pacing
 Prior to the implant of a permanent
pacemaker
Temporary support of a patient after heart
surgery
 Acute myocardial infarction complicated
by heart block
 High rate burst stimuli for the treatment of
some tachyarrhythmias
The NASPE/BPEG Generic (NBG) Code
Position
I
Category Chamber(s)
Paced
II
III
IV
V
Chamber(s)
Sensed
Response to
Sensing
Programmability
Rate Modulation
Antitachyarrhythmia
Function(s)
O = None
O = None
O = None
O = None
O = None
A = Atrium
A = Atrium
T = Triggered
P = Simple Programmable
P = Pacing
V = Ventricle
V = Ventricle
I = Inhibited
M = Multiprogrammable
S = Shock
D = Dual (A+V)
D = Dual (A+V)
D = Dual (T+I)
C = Communicating
D = Dual (P+S)
R = Rate Modulation
Manufacturer’sS = Single
Designation
(A or V)
Only
S = Single
(A or V)
Note: Positions I through III are used exclusively for antibradyarrhythmia function
Asynchronous Modes
AOO
VOO
DOO
DVI
1
2
3
Ap
*
Ap
*
*
Vp

Vs
4
Ap
*
*
Vp
= AV interval (140 ms)
= PVARP (250 ms)
= indicates cycle restarted
by sensed or paced event
*
Vp
5
Ap
*
6
Ap
*
*
Vp
Lower rate = 60 ppm
V-A interval = 860 ms
*
Vp
DDD Pacing
Chamber Paced
Chamber Sensed
Action or Response
to a Sensed Event
D
D
D
DDD Pacemaker
Provides:
 AV Synchrony
 Rate Variability
Results in:
 Changes in cardiac output
 Management of rhythm
 Improved quality of life
Parameter Adjustments of the
Temporary DDD Pacemaker
 Lower Rate
 A–V Interval
 Upper Rate
 Output
 Sensitivity
 Refractory Period
(PVARP)
ECG Function DDD Mode
Timing Intervals in milliseconds (ms)
V–A
A–V
750 ms 250 ms
V–V
1000 ms
DDD / 60 / 250 / 125 / 155
Calculation of Atrial Escape Interval
Atrial Escape
Interval
Lower Rate
–
A–V Interval
=
V–V
(ms)
–
A–V
(ms)
=
V–A
(ms)
(60 ppm)
1000
–
250
=
750
(60 ppm)
1000
–
150
=
850
(70 ppm)
850
–
200
=
650
Proper Atrial Sensing
is the “Heart” of
Physiologic Pacing
A Pace / V Pace
A–V Sequential Pacing
V–A
A–V
750 ms 250 ms
V–V
1000 ms
DDD / 60 / 250 / 150
A Pace / V Sense
Atrial Pacing with Normal A–V Conduction
DDD / 60 / 200 / 150
Programmed Lower Rate
1000 ms
Actual V–V
960 ms
A Sense / V Pace
Atrial Synchronous Pacing
Spontaneous Atrial Rate = 55 ppm
DDD / 50 / 150 / 150
Spontaneous Atrial Rate = 110 ppm
A Sense / V Sense
Spontaneous P-Wave with Normal A–V Conduction
Spontaneous Atrial Rate = 65 ppm
Spontaneous P-R Interval = 160 ms
DDD / 60 / 200 / 150
Timing Operations of DDD Pacing
Ventricular
Rate
Upper
Rate
Atrial
Tracking
Lower
Rate
Atrial Rate
Definitions
PVARP – Post Ventricular Atrial Refractory Period
Time after Vs or Vp when
atrial rates are ignored
A–V
– Time from As or Ap to Vp in ms
TARP
– Total Atrial Refractory Period in ms
Refractory Period

Increase to prevent:
– T-wave sensing
– P-wave sensing

Decrease to permit tachy pacing
Wenckebach Operation
Wenckebach Operation
AV
AV W
PVARP
AV W
PVARP
Upper Rate
As
AV
PVARP
Upper Rate
As
W
AV
PVARP
Upper Rate
As
PVARP
Upper Rate
As
Upper Rate
As
As
Vp
Vp
W = Wenckebach Interval
Vp
Vp
Vp
2 : 1 Block
2 : 1 Block
AV
AV
AV
AV
PVARP
PVARP
PVARP
PVARP
Upper Rate
Upper Rate
Upper Rate
Upper Rate
As
As
Vp
As
As
Vp
As
As
Vp
As
As
Vp
Physiology of Retrograde Conduction
1. Loss of A-V synchrony due
to a PVC
2. Sensed retrograde activation
3. A-V interval initiated
PVC4.
Prolongation of A-V interval
5. Ventricular pacing
synchrononized to retrograde
P-waves
Pacemaker Mediated Tachycardia
(PMT)

Fast ventricular paced rhythm
 Synchronized to retrograde-
conducted P-waves
 Not normal sinus tachycardia
Thresholds
Feature of the Temporary DDD Pacemaker
Output Control
Atrial
Ventricular
Pulse Amplitude
(ma)
Pulse Width
(ms)
Feature of the Temporary DDD Pacemaker
Sensitivity
2.5
1.25
0.5
Troubleshooting
Undersensing
Failure of the pacemaker to sense
intrinsic R-waves or intrinsic P-waves
Undersensing
 Battery depletion
 Decreased QRS voltage
 Fusion beat
 Dislodged/fractured lead
 Inappropriate sensitivity setting
Oversensing
Inhibition of the pacemaker by events the
pacemaker should ignore, e.g. EMI, T-waves,
and myopotential
Oversensing
 Myopotential inhibition
 EMI
 T-waves outside of refractory period
 Dislodged/fractured lead
 Inappropriate sensitivity setting
No Output
Pacemaker fails to emit stimuli
at the programmed intervals
No Output
1
AP
VP
2
AS
VP
3
AP
VP
4
AP
VP
5
AP
VP
No atrial output (on ECG)
 Battery depletion/pacemaker off
 Faulty cable connection
 Oversensing
 Dislodged/fractured lead
Loss of Capture
Electrical stimuli delivered by
the pacemaker does not initiate
depolarization of the atria or ventricle
Loss of Capture
Atrial
Noncapture
Ventricular
Noncapture Fusion
 Inappropriate output setting
 Dislodged/fractured lead
 Increased resistance to conduction
 Tissue is refractory
 QRS complex not visible
 Faulty cable connection
Ventricular Safety Pacing
Ap
Ap = Atrial Pace
Vp = Ventricular Pace
Ventricular Blanking
at Atrial Rate
Vp
Programmed
A-V Interval
12 ms
Ventricular Safety
Pace Interval
110 ms
Programmed
A-V Interval
Ventricular Sensing within this
period triggers a ventricular output
at an A-V interval of 110 ms instead
of programmed A-V interval.
Ventricular Sensing during the remainder
of the programmed A-V interval inhibits
the ventricular output. If there is no
sensed event, a ventricular output occurs
at the programmed A-V interval.
Ventricular Safety Pacing (VSP)
1
Ap
*
*
Vs Vp
2
Ap
*
3
4
Ap
*
Ap
*
Ap
*
*
Vs Vp
*
Vs Vp
*
Vp
*
Vp
= AV interval (160 ms)
= PVARP (250 ms)
= indicates cycle restarted
by sensed or paced event
Lower rate = 54 ppm
Upper rate = 180 ppm
V-A interval = 860 ms
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