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Pacemakers
Jonathan MacCabe
November 15, 2004
Pacemaker Indications

Acquired A/V block in Adults
– Class I: There is general agreement that permanent
pacemakers should be implanted.

Complete heart block, permanent or intermittent, at an
anatomic level associated with any on of the following
complications:
– Symptomatic bradycardia. In the presence of complete heart block
symptoms must be presumed to be due the heart block unless
proved otherwise
– Congestive heart failure
– Ectopic rhythms and other medical conditions that require drugs
that suppress the automaticity of escape rhythms and result in
symptomatic bradycardia.
– Documented periods of asystole >= 3.0 s or any escape rate
<40/min. in symptom free patients
– Confusional states that clear with temporary pacing
– Post A/V junctional ablation, myotonic dystrophy
Pacemaker Indications

Acquired A/V block in Adults
– Class I: There is general agreement that permanent
pacemakers should be implanted.


Second degree A/V block permanent or intermittent,
regardless of the type or the site of the block, with
symptomatic bradycardia.
Atrial fibrillation, Atrial flutter and rare cases of SVT
with complete or advanced A/V block, bradycardia and any of
the conditions in A1. The bradycardia must be unrelated to
digitalis or drugs known to impair A/V conduction.
Pacemaker Indications

Acquired A/V block in Adults
– Class II: Conditions in which permanent pacemakers are
frequently used but there is some divergence of opinion
about whether they are needed.



Asymptotic complete heart block, permanent or intermittent,
at any anatomic site, with ventricular rates of 40/min. or
faster
Asymptomatic type ll second degree block, permanent or
intermittent
Asymptomatic type I second degree block at intra-His or
infra-His levels.
– Class III: Conditions in which there is general agreement
that pacemakers are not necessary.


First degree A/V block
Asymptomatic type 1 second degree A/V block at the suprahis level.
Pacemaker Indications

AV Block Associated with Myocardial
Infarction:
– Class I: There is general agreement that permanent
pacemakers should be implanted.


Persistent advanced second degree A/V block or complete
heart block after acute myocardial infarction with block in he
His-Purkinje system
Patients with transient advanced A/V block and associated
bundle branch block
Pacemaker Indications

AV Block Associated with Myocardial
Infarction:
– Class II: Conditions in which permanent pacemakers are
frequently used but there is some divergence of opinion
about whether they are needed.

Patients with persistent advanced block in the A/V node
– Class III: Conditions in which there is general agreement
that pacemakers are not necessary.



Transient A/V conduction disturbances in the absence of
intraventricular conduction defects
Transient A/V block in the presence of isolated left anterior
hemiblock
Acquired left anterior hemiblock in the absence of A/V block.
Pacemaker Indications

Bifasicular and Trifasicular Block (chronic)
– Class I: There is general agreement that permanent
pacemakers should be implanted.
 Bifasicular block with intermittent complete heart block
associated with symptomatic bradycardia
 Bifasicular or Trifasicular block with intermittent type ll
second degree A/V block without symptoms
attributable to the heart block.
Pacemaker Indications

Bifasicular and Trifasicular Block (chronic)
– Class II: Conditions in which permanent pacemakers are
frequently used but there is some divergence of opinion
about whether they are needed.



Bifasicular or trifasicular block with syncope that is not
proved to be due to complete heart block, but other possible
causes for syncope are not identifiable
Markedly prolonged HV (>100ms)
Pacing-induced infra-His block
– Class III: Conditions in which there is general agreement
that pacemakers are not necessary.


Fasicular block without A/V block or symptoms
Fasicular block with first degree block without symptoms
Pacemaker Indications

Sinus Node Dysfunction:
– Class I: There is general agreement that permanent
pacemakers should be implanted.

Sinus node dysfunction with documented symptomatic
bradycardia. In some patients this will occur as a
consequence of long-term (essential) drug therapy of type
and dose for which there are no acceptable alternatives.
– Class II: Conditions in which permanent pacemakers are
frequently used but there is some divergence of opinion
about whether they are needed.

Sinus node dysfunction occurring spontaneously or as a
result of necessary drug therapy, with heart rates <40/min.
when a clear association between significant symptoms
consistent with bradycardia and the actual presence of
bradycardia has not been documented.
Pacemaker Indications

Sinus Node Dysfunction:
– Class III: Conditions in which there is general agreement
that pacemakers are not necessary.
 Sinus node dysfunction in asymptomatic patients
including those in whom substantial sinus bradycardia
(heart rate < 40/min.) is a consequence of long-term
drug treatment
 Sinus node dysfunction in patients in whom symptoms
suggestive of bradycardia are clearly documented not
to be associate with a slow heart rate.
Pacemaker Indications

Hypersensitive Carotid Sinus and
Neurovascular Syndromes
– Class I: There is general agreement that permanent
pacemakers should be implanted.

Recurrent syncope associates with clear, spontaneous events
provoked by carotid sinus stimulation; minimal carotid sinus
pressure induces asystole of >3 sec. duration in the absence
of a medication that depresses the sinus node or A/V node
– Class II: Conditions in which permanent pacemakers are
frequently used but there is some divergence of opinion
about whether they are needed.


Recurrent syncope without clear, provocative events and with
a hypersensitive cadrioinhibitory response.
Syncope with associated bradycardia reproduced by a headup tilt with or without isoproterenol or other forms of
provocative maneuvers and in which a temporary pacemaker
and second provocative test can establish the likely benefits
of a permanent pacemaker
Pacemaker Indications

Hypersensitive Carotid Sinus and
Neurovascular Syndromes
– Class III: Conditions in which there is general agreement
that pacemakers are not necessary.



A hyperactive cardioinhibitory response to carotid sinus
stimulation in the absence of symptoms.
Vague symptoms, such s dizziness or light-headedness or
both, with a hyperactive cardioinhibitory response to carotid
sinus stimulation.
Recurrent syncope, light-headedness or dizziness in the
absence of a cardioinhibitory response.
The
NASPE /
BPEG
Generic (I.C.H.D.)
The NASPE/BPEG Generic (NBG) Code
Position
I
II
III
IV
V
Category
Chamber(s)
Paced
Chamber(s)
Sensed
Response
to Sensing
Programmability,
rate modulation
Antitachyarrhythmia
Function(s)
Letters
Used
O-None
O-None
O-None
A-Atrium
A-Atrium
V-Ventricle
V-Ventricle
D-Dual
(A+V)
D-Dual
(A+V)
T-Triggered P-Simple
P-Pacing
Programmable
(antitachyI-Inhibited
arrhythmia)
M-MultiD-Dual
Programmable S-Shock
(T+I)
C-Communicating D-Dual
(P+S)
R-Rate
modulation
S- Single
(A or V)
S- Single
(A or V)
Manufacturer’s
Designation
Only
O-None
O-None
Codes Are Combined To
Describe:



The mode of pacing
The mode of sensing
How the pacemaker will respond to the
presence or absence of intrinsic beats
-
AOO
-
AAI
-
VOO
-
VVI
The NASPE/BPEG Generic (NBG) Code
Position
I
II
III
IV
V
Category
Chamber(s)
Paced
Chamber(s)
Sensed
Response
to Sensing
Programmability,
rate modulation
Antitachyarrhythmia
Function(s)
Letters
Used
O-None
O-None
O-None
A-Atrium
A-Atrium
V-Ventricle
V-Ventricle
D-Dual
(A+V)
D-Dual
(A+V)
T-Triggered P-Simple
P-Pacing
Programmable
(antitachyI-Inhibited
arrhythmia)
M-MultiD-Dual
Programmable S-Shock
(T+I)
C-Communicating D-Dual
(P+S)
R-Rate
modulation
S- Single
(A or V)
S- Single
(A or V)
Manufacturer’s
Designation
Only
O-None
O-None
The NASPE/BPEG Generic (NBG) Code
Position
I
II
III
IV
V
Category
Chamber(s)
Paced
Chamber(s)
Sensed
Response
to Sensing
Programmability,
rate modulation
Antitachyarrhythmia
Function(s)
Letters
Used
O-None
O-None
O-None
A-Atrium
A-Atrium
V-Ventricle
V-Ventricle
D-Dual
(A+V)
D-Dual
(A+V)
T-Triggered P-Simple
P-Pacing
Programmable
(antitachyI-Inhibited
arrhythmia)
M-MultiD-Dual
Programmable S-Shock
(T+I)
C-Communicating D-Dual
(P+S)
R-Rate
modulation
S- Single
(A or V)
S- Single
(A or V)
Manufacturer’s
Designation
Only
O-None
O-None
The NASPE/BPEG Generic (NBG) Code
Position
I
II
III
IV
V
Category
Chamber(s)
Paced
Chamber(s)
Sensed
Response
to Sensing
Programmability,
rate modulation
Antitachyarrhythmia
Function(s)
Letters
Used
O-None
O-None
O-None
A-Atrium
A-Atrium
V-Ventricle
V-Ventricle
D-Dual
(A+V)
D-Dual
(A+V)
T-Triggered P-Simple
P-Pacing
Programmable
(antitachyI-Inhibited
arrhythmia)
M-MultiD-Dual
Programmable S-Shock
(T+I)
C-Communicating D-Dual
(P+S)
R-Rate
modulation
S- Single
(A or V)
S- Single
(A or V)
Manufacturer’s
Designation
Only
O-None
O-None
The NASPE/BPEG Generic (NBG) Code
Position
I
II
III
IV
V
Category
Chamber(s)
Paced
Chamber(s)
Sensed
Response
to Sensing
Programmability,
rate modulation
Antitachyarrhythmia
Function(s)
Letters
Used
O-None
O-None
O-None
A-Atrium
A-Atrium
V-Ventricle
V-Ventricle
D-Dual
(A+V)
D-Dual
(A+V)
T-Triggered P-Simple
P-Pacing
Programmable
(antitachyI-Inhibited
arrhythmia)
M-MultiD-Dual
Programmable S-Shock
(T+I)
C-Communicating D-Dual
(P+S)
R-Rate
modulation
S- Single
(A or V)
S- Single
(A or V)
Manufacturer’s
Designation
Only
O-None
O-None
VOO
• Ventricular pacing
• No sensing
• Ventricular asynchronous pacing
at lower programmed pacing rate
Ventricular
lead
*
AOO
• Atrial pacing
Atrial lead
*
• No sensing
• Atrial asynchronous
pacing at lower
programmed pacing rate
VVI
• Ventricular pacing
• Ventricular sensing
• Sensed intrinsic QRS
inhibits ventricular pacing
Ventricular
lead
*
AAI
• Atrial pacing
• Atrial sensing
Atrial lead
*
• Intrinsic P wave inhibits
atrial pacing
Dual Chamber Pacing
DDD
• Pacing in both the atrium
and ventricle
Atrial
lead
Ventricular
Lead
T/I
I
• Sensing in both the atrium
and ventricle
*
• Intrinsic P wave and intrinsic
QRS can inhibit pacing
*
• Intrinsic P Wave can
“trigger” a paced QRS
DDD pacing


Dual-chamber pacing capable of pacing and
sensing in both the atrial and ventricular
chambers of the heart
4 distinct patterns can be observed with
DDD pacing
– Sensing in the atrium and sensing in the ventricle
– Pacing in the atrium and sensing in the ventricle
– Sensing in the atrium and pacing in the ventricle (“P wave
tracking”)
– Pacing in the atrium and pacing in the ventricle
DDD pacing

Example of sensing in both the atrium
and the ventricle (inhibiting in both
the atrium and the ventricle)
DDD pacing

Example of pacing in the atrium with
sensing (inhibition of pacing) in the
ventricle
DDD pacing


Example of sensing in the atrium (inhibition
of atrial pacing) and pacing in the ventricle
Also known as “P wave tracking”
DDD pacing

Example of atrial pacing and
ventricular pacing (no inhibition of
pacing)
DDD Pacing



Adapts to changes post-implant
May resemble AAI, VAT, VDD, DVI
modes
Will strive to maintain AV synchrony
with variable atrial rates and AV
conduction
AV Synchrony
Cardiac Output = Stroke Volume x Heart Rate



Facilitates venous return
Increases LVEDP
Maintains appropriate opening and
closing
of A-V valves
Pacemaker Syndrome
Loss of AV Synchrony






Shortness of breath
Fatigue
Headache
Syncope
Vertigo
CHF, Pulmonary
Edema






Dizziness
Palpitations
Pulsations in the
neck
Chest pain
Near Syncope
Confusion
Hemodynamic
Penalties From Loss
Of AV Synchrony





Loss of atrial
contribution
Decrease in stroke
volume
Decrease in cardiac
output
Decrease in cerebral
perfusion
Decrease in coronary
blood flow
Treatment of
Pacemaker
Syndrome



Dual-chamber pacing
Normal atrial sensing &
capture
Appropriate AV Delay
Goals of Choosing a
Pacing Mode

Desire to maintain AV synchrony
– DDD mode is best to provide AV
synchrony

Preservation of AV synchrony requires:
– Viable atrium and
– Patient must not have chronic/permanent
atrial tachyarrhythmias
Optimal Pacing Mode Decision Tree
Pacemaker is indicated
What is the condition of the SA Node?
Chronic atrial fibrillation
unexcitable atrium
Normal or sinus
bradycardia
Is the patient
chronotropically
incompetent?
Is the patient
chronotropically
incompetent?
Y
N
N
Y
DDDR
VVIR
Is AV conduction
adequate?
DDD
VVI
Is the patient
chronotropically
incompetent?
Y
DDDR
Ventricular
Pacing
AV Synchrony
Y
N
N
DDD
Is the patient
chronotropically
incompetent?
Y
AAIR
AV Synchrony
N
AAI
AV Synchrony - DDD(R)
Pacemaker is indicated
• Benefits
– AV synchrony
– Normal sinus response
• Risks
– Loss of AV conduction
What is the condition of the SA node??
Normal or sinus
bradycardia
Is AV conduction
adequate?
N
Is the patient
chronotropically
incompetent?
Y
DDDR
N
DDD
Ventricular Pacing
Pacemaker is indicated
Chronic atrial fibrillation
unexcitable atrium
Is the patient
chronotropically
incompetent?
Y
VVIR
N
VVI
What is the condition of the SA node?
• Benefits
– Maintain minimum cardiac output
– Single-lead implantation
• Risks
– Loss of AV synchrony
– Retrograde conduction
– Increased incidence of atria arrhythmias
Rate Modulation/Rate
Responsive Mode
Rate Responsiveness/AdaptiveRate Pacing


In Rate Responsive pacing (modes ending with
“R”), sensor(s) in pacemaker are used to detect
changes in physiologic needs and increase the
pacing rate accordingly
The sensor
– Sensors are used to detect changes in metabolic demand
– Sensors sense motion (piezoelectric crystal or
accelerometer) or use a physiologic indicator, e.g., minute
ventilation

The algorithm
– Within the software of the pacemaker
– Uses the input from the sensor to determine the
appropriate paced heart rate for the activity
DDDR Pacing

Example of Dual-Chamber RateResponsive pacing
DDDR
A DDDR pacemaker has two or more
indicators of a patient’s metabolic
need:
– Sinus node – the best indicator, as it is
physiologic
– Input from the sensor(s) within the
pacemaker
Pacemaker Timing and
Function
Lower Rate Limit
LRL
LRL
LRL
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
Ventricular Tachycardia
Limit (Upper Rate Limit)
VTL VTL VTL
LRL
60 ppm
VTL
120 ppm
AVD
150 ms
PVARP
250 ms
DDD-09
A-V Delay
AVD
AV
AV
AVD
AVD
AV
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
A-V Delay
AV p
AV s
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
Avs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
Atrial Refractory Periods
TARP
AVD PVARP
LRL
60 ppm
PVARP = Post Ventricular Activation Refractory Period
VTL
120 ppm
TARP = Total Atrial Refractory Period
AVD
200 ms
TARP = AVD + PVARP
PVARP
250 ms
TARP
450 ms
Atrial Refractory Periods
PVARP
Note: this P wave does not trigger
ventricular pacing because it falls
within the PVARP
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-16
Pacemaker Malfunctions
Failure to Capture
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
DDD-22
Failure to Capture
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
DDD-23
Failure to Sense
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
TARP
450 ms
DDD-02
Pacemaker Associated
Heart Block
LRL
60 ppm
VTL
120 ppm
AVD
150 ms
PVARP
350 ms
DDD-12
Pacemaker Associated
Heart Block
Note: AVD is extended to preserve
the upper rate limit
LRL
60 ppm
VTL
120 ppm
AVD
150 ms
PVARP
250 ms
DDD-14
“Pacemaker Wenkebach”
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-15
Pacemaker Associated
Tachycardia
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-17
Pacemaker Associated
Tachycardia
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-18
continuous
LRL
60 ppm
AVs
VTL
100 ppm
Min. Adap. A-V
AVp
200 ms
PVARP
150 ms
88 ms
250 ms
DDD-19
Oversensing
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-20
Oversensing with Safety
Pacing
LRL
60 ppm
VTL
120 ppm
AVp
200 ms
AVs
150 ms
Min. Adap. A-V
PVARP
88 ms
250 ms
DDD-21
Is This a Pacemaker
Malfunction?
Normal DDD Pacing
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
DDD-08
Normal DDD Pacing
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
TARP
450 ms
DDD-01
Normal DDD Pacing
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
DDD-07
Fusion
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
DDD-05
Safety Pacing
LRL
60 ppm
VTL
120 ppm
AVD
200 ms
PVARP
250 ms
TARP
450 MS
DDD-04
The End