植入性心臟電子儀器(CIEDs)
的基本原理及設定

高雄長庚醫院 心臟內科 陳煌中 醫師
2013.10.19 (W6) 蓮潭會館
Outlines
• Introduction of CIEDs (cardiovascular
implantable electronic devices)
• General Setting of PPM
– Pacing, sensing, capture
– Low rate, upper rate
– Pacing mode
– Refractory and blanking period
– Other setting
Reference
Cardiac Conduction Review

Atria
SA node
Ventricles
AV node

Bundle
branches
Implantable Pacemaker System
Lead wire(s)

Implantable pulse
generator (IPG)
• Battery
• Circuitry
• Connector(s)

Connector
Block
Circuitry
Battery

Myocardial tissue
Lead Characterization
Passive Fixation Leads

Active Fixation Leads

Epicardial Leads

Bipolar coaxial lead
Characteristics of an Electrical Circuit
• Voltage (V)
– Voltage is the force, or “push,” that
causes electrons to move through a
circuit
– Provided by the pacemaker battery

• Current (I)
– Determined by the amount of
electrons that move through a circuit
– Cause myocardial cells to depolarize

• Impedance (R or W)
– The opposition to current flow
– All resistance: conductor, electrode,
myocardium

V
I R
Battery Capacity and Longevity
Battery Capacity and Longevity
Voltage and Current Flow
Electrical Analogies

Spigot (voltage) turned up, lots of
water flows (high current drain)
Water pressure in system is
analogous to voltage – providing
the force to move the current

Spigot (voltage) turned low, little flow
(low current drain)
Lead Impedance, 300~1500 Ohm
High impedance

Conductor failure, impedance >2500 Ohm

Low impedance

Insulation defect, Impedance <300 Ohm
The Revised NASPE/BPEG Generic (NBG)
Code for Antibradycardia Pacing
I

II

III

IV

V

Chamber(s)
Paced

Chamber(s)
Sensed

Response to
Sensing

Rate
Modulation

Multisite
Pacing

O = None

O = None

O = None

O = None

O = None

A = Atrium

A = Atrium

T = Triggered

R = Rate

A = Atrium

V = Ventricle

V = Ventricle

I = Inhibited

D = Dual (A + V)

D = Dual (A + V)

D = Dual (T + I)

modulation

V = Ventricle
D = Dual (A + V)

S = Single (A or V) S = Single (A or V)
NASPE is the North American Society of Pacing and Electrophysiology
BPEG is the British Pacing and Electrophysiology Group
BERNSTEIN, et al.; PACE 2002; 25:260–264
Which mode is appropriate?
Indication
• DDD(R)
• complete AV block
• sinus nodal dysfunction
• paroxysmal atrial fibrillation
• AAI(R)
• sinus nodal dysfunction
• VVI(R)
• permanent atrial fibrillation

AAI/AAIR

DDD/DDDR
VVI/VVIR
Optimal Pacing Mode in
Sinus Node Disease and AV Block

2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy
Programmability
General Setting of Pacemaker
Parameter
Base Rate

Description
Pacing timing cycle

Maximum Sensor
Rate (MSR) is the
Max.
highest pacing rate
Sensor rate
allowed by ratemodulated pacing

Max
Tracking
Rate

upper limit of the
ventricular pacing
rate in response to
the patient’s intrinsic
atrial activity

Setting

Recommendation

•Depends on patient’s need Hysteresis
•Nominal setting 60-70 bpm Rest rate
•Depends on patient’s age
and activity (220-Age)X0.85

•Depends on patient’s age
and activity (220-Age)X0.85
•Also has to consider the
other cardiac disease
General Setting of Pacemaker
Parameter

Description

Setting
• AVB : 200-150
• SSS : depends on
the AV conductivity,
nominal less than
300ms

Recommendation

Reduce unnecessary
ventricular pacing
 VIP/AICS/AV
hysteresis /MVP

AV/PV delay

AV : internal of Ap to Vp
PV : interval of As to Vp

Rate
responsive
AV/PV delay

shorten AV/PV Delay when
the atrial rate is higer then 90
bpm, to mimic physical
Off, slow, mid, high
demand, also allows setting
higher MTR

Pulse
Amplitude,
Pulse width
(A, V)

determines how much
electrical potential is
applied to the myocardium
during the pacing stimulus

Nominal setting
2.5V@0.4ms

• 2-3 times of
threshold to
secure capture
• AutoCapture

A/V
sensitivity

This parameter determines
the amplitude of signals to
which the device’s sense
amplifiers will respond

• A : 0.5~1.0 mV
• V : 2~3 mV

Higher level indicate
less sensitive to P/R
wave
Pacemaker Code
• Very useful in helping you understand how
the IPG is interpreting events
• Code:
– AS  Atrial Sense
– AP  Atrial Pace
– AR  Atrial Refractory
– VS  Ventricular Sense
– VP  Ventricular Pace
– VR  Ventricular Refractory
Sensing, Pacing, Capture
Pacemaker Sensing
Sensing Threshold
Output Pulse of Pacemaker
Pacing Threshold
Pulse Amplitude and Width (Duration)

No Capture!

No Capture!
Strength – Duration Curve
Safety Ratio for Capture
Safety Ratio for Capture
Automatic Stimulation Threshold Search
Lower rate, Rest rate, Upper rate
Lower Rate Interval (LRI) - VVI
• The lowest rate the pacemaker will pace the heart
in the absence of intrinsic events
LRI

LRI
Hysteresis
• Allows the rate to fall below the programmed
lower rate following an intrinsic beat

60 bpm

50 bpm
Rest Rate
• Allows the pacemaker to decrease the base rate to
•
•

the programmed auto rest rate during periods of
inactivity.
People spend about 7 hours, out of a 24 hour day,
sleeping, therefore 29% of the time is spent
sleeping.
The pacemaker calculates where this 29% would
occur based on the Activity Variance Histogram and
establishes this point as threshold.
“R” = Rate Response
• When the need for oxygenated blood increases, the
pacemaker ensures that the heart rate increases to
provide additional cardiac output.
Rate-Adaptive Pacing
Rate-Adaptive Pacing: Accelerometer
Accelerometer

•
•
•
•
•
•

Low current drain
Easy to manufacture
Rapid response to onset of activity
Compatible with standard pacing leads
Not responsive to pressure applied to can
Used in all current St. Jude Medical
pacemakers (began with Trilogy DR+)

Circuit Board
Rate-Adaptive Pacing
• The Sensors—Physiology
– Evoked response
• The QRS depolarization decreases
in area with exercise
• Works only when the device is
pacing

– QT interval
• QT interval shortens with exercise
• Works only when the device is
pacing
Rate-Adaptive Pacing: St. Jude
• Reactive time and recovery time
Upper Rate Response
• Dual-chambers pacemakers try to maintain 1:1 AV
synchrony but this is not always possible
• In the presence of high intrinsic atrial rates,
pacemakers may revert to upper rate responses
Upper Sensor Rate
• Defines the shortest interval (highest rate) the
pacemaker can pace as dictated by the sensor (AAIR,
VVIR modes)
Tracking
Upper Tracking Rate (UTR)
• The maximum rate the ventricle can be paced in
response to sensed atrial events
Lower Rate Interval

{

Upper Tracking Rate Limit
SAV

AS

VP

VA

SAV

AS

VA

VP

DDDR 60 / 100 (upper tracking rate)
Sinus rate: 100 bpm
Upper Rate Behavior

Ventricular Rate

UTR

LR

1:1 Atrial
Tracking

No
Ventricular
Pacing

LR

= Ventricular Pacing

Wenckebach

UTR

Atrial Rate

TARP

2:1 Block
Wenckebach Operation

DDD / 60 / 120 / 310
2:1 Block

DDD / 60 / 120 / 310
Upper Rate Behavior – 2:1 Block
Wenckebach vs. 2:1 Block
• If the upper tracking rate interval is longer
than the TARP, the pacemaker will exhibit
Wenckebach behavior first.
• If the TARP (total atrial refractory period) is
longer than the upper tracking rate interval,
then 2:1 block will occur.
Pacing Mode
AAI Mode
VVI Mode
DDD Mode
Benefits of Dual Chamber Pacing
• Provides AV synchrony
– Lower incidence of atrial fibrillation
– Lower risk of systemic embolism and stroke
– Lower incidence of new congestive heart failure
– Lower mortality and higher survival rates
The Magnet Test (VOO Mode)
Magnet ECG – St. Jude
Magnet ECG – Medtronic
Refractory & Blanking Period
Blanking and Refractory Periods
• Blanking Period
– A period of time during which the sense amplifiers
are off, and the pacemaker is “blind”.
– Designed to prevent oversensing pacing stimulus

• Refractory Period
– A period of time during which sensed events are
ignored for timing purposes, but included in
diagnostic counters
– Designed to prevent inhibition by cardiac or noncardiac events
Why Do We Use Refractory and
Blanking Periods?
• Pacemaker sensing occurs when a signal is large
enough to cross the sensing threshold
5.0 mV

Sensing does not tells us
anything about the origin or
morphology of the sensed
event, only its “size.”

2.5 mV
1.25 mV

1.25 mV Sensitivity

Time
Why Do We Use Refractory and
Blanking Periods?
• By manipulating the sense amplifiers, we filter
signals based on their relationship
The potential for digitizing
these signals may someday
allow pacemakers to
discriminate signals based
on morphology rather than
just on their relationship.

5.0 mV

2.5 mV

SENSE!

1.25 mV

Sensing

Blanking

Time

Refractory
Blanking Periods
• Atrial Blanking (AB)
– A non-programmable atrial blanking period (50-100 ms) from
atrial paces or senses.
– Avoid the atrial lead sensing its own pacing pulse or P wave
(intrinsic or captured).

• Ventricular blanking (VB)
– 50-100 ms in duration and is dynamic, based on signal strength.
– After a ventricular paced or sensed event to avoid sensing the
ventricular pacing pulse or the R wave (intrinsic or captured).

• Post ventricular atrial blanking (PVAB)
– Initiated by a ventricular pace or sensed event (220 ms)
– Avoid the atrial lead sensing the far-field ventricular output
pulse or R wave.
Ventricular Blanking
• The first portion of the refractory period
• Pacemaker is “blind” to any activity
• Designed to prevent oversensing pacing stimulus
Lower Rate Interval

VP
Blanking Period
Refractory Period

VP

VVI / 60
Blanking Periods
Ventricular Refractory and Blanking Periods
PVAB
ARP

Post Atrial
Ventricular
Blanking

PVARP
VRP

Ventricular Refractory
Period

Ventricular
Blanking
AV Crosstalk
• Atrial pacing spike will be detected in the ventricle.
• Will inhibit ventricular pacing
Add PAVB to Prevent AV Crosstalk
Blanking Periods
Atrial Refractory and Blanking Periods
Post Ventricular Atrial
Blanking

Atrial Blanking

PVAB
ARP

PVARP

VRP

Atrial Refractory Period

Post Ventricular Atrial
Refractory Period
Refractory Periods
• VRP and PVARP are initiated by sensed or paced
ventricular events.
– The VRP is intended to prevent self-inhibition such as
sensing of T-waves.
– The PVARP is intended primarily to prevent sensing of
retrograde P waves, far-field R wave, or premature atrial
contractions.
Ventricular Refractory Period
1000 ms

1000 ms

VRP 320 ms

Blanking

V
P

VRP 320 ms

V
R

V
P

Refractory

• Pacemaker VRP avoids the sensing of :
–
–
–
–
–

Its own stimulus
The paced QRS complex
The T wave
(Excessive) afterpotential
The combination of T wave and afterpotential

V
R
Pacemaker Mediated Tachycardia (PMT)
Evaluation of Retrograde VA Conduction

PVARP
Prevention of PMT
• Prevention
– Extend PVARP (Post Ventricular Atrial Refractory
Period)
– Program PVARP 50 ms longer than measured
retrograde VA conduction (RVAC)
• Use VVIR mode to determine the RVAC
Algorithms for automatic
Termination of PMT
AV Delays
The 4 Fundamental Timing Cycle of a
DDD Pacemaker
AV Delay or AV Interval (AVI)
• AVI is the interval between an atrial event (either sensed or
paced) and the scheduled delivery of a ventricular stimulus.
• Typical sAVI is 30-50 ms shorter than pAVI (sAVI < pAVI).
• The AV intervals may be programmed to fixed values or
rate-adaptive (i.e. shortening with increasing atrial rates).
The Rate-Adaptive Interval
• The rate-adaptive AV interval mimics the physiologic
response of the heart.
The 4 Fundamental Timing Cycle of a
DDD Pacemaker
Other Setting
Automatic Mode Switching (AMS)
• AMS turns off atrial tracking in the presence of
intrinsic atrial activity above a programmable atrial
rate cutoff.
• Mode will switch from tracking mode (DDDR, DDD)
to DDIR (non-tracking mode) when atrial
arrhythmia is detected.
• AMS can cause a sudden rate decrease as atrial
tracking.
• Ventricular pacing is decoupled from atrial events,
but rate responsive pacing is matched to metabolic
needs.
Mode Switch
• The device detects an atrial arrhythmia by constantly
comparing intervals with the programmed mode
switch detection rate.
MS

DDD / 60 / 120 Mode Switch ON
減少右心室電刺激 = 減少心衰竭住院
及心房顫動

Risk of AF Relative to
DDDR Patient With
Cum%VP=0

MOST study

Every incremental 1% of unnecessary VP increases the
risk for Heart Failure Hospitalizations by 5.4%

There is a 1% increase in the risk of AF for each 1%
increase in cumulative right ventricular pacing.
Within 95%
Confidence

Risk of AF
Cumulative % Ventricular Pacing
Ventricular Intrinsic Preference (VIP)
• VIP activation
– Device extends AV delays by 160 ms searching for Rwaves for up to 3 cycles in our example
– R-waves found within 1 cycle, therefore, AV delay
remains at lengthened value
Ventricular Intrinsic Preference (VIP)
• VIP deactivation
– Device extends AV delays by 160 ms searching for Rwaves for up to 3 cycles in our example
– No R-waves found within 3 cycle, therefore, AV delays
returns to programmed values.

1

2

3
Ventricular Intrinsic Preference (VIP)
• VIP most beneficial
–
–

Intermittent AV block
Mild prolongation of AV conduction

• VIP not beneficial
–
–
–

Complete permanent AV block
Marked 1st degree AV block
If CRT therapy is indicated

• VIP clinical benefits
– Less risk of heart failure progression
– Less risk of developing AF
– Better QoL trough improved hemodynamics
MVP AAI (R) to DDD(R)Pacing (MVP)
Managed Ventricular
Operation
Switch from AAI(R) to Temporary DDD(R) Mode
Ventricular support if loss of A-V conduction is persistent.
2 out of 4 Most Recent A-A Intervals with No Conducted VS Event

No VS
Conduction

Ventricular Back-Up
Pace at 80 ms Post
the Scheduled AP

Switch to DDD(R) occurs after
back-up VP; programmed PAV/SAV are
used during this mode of operation
Intracardiac Defibrillator (ICD)
Dual Coil Lead

Single Coil Lead
Cold Can

Proximal
Shock
Electrode

Hot Can
Distal
Shock
Electrode
Cardiac Resynchronization Therapy
Goal: Mitigate dyssynchrony
through atrial synchronous
biventricular pacing

Right Atrial
Lead

Left Ventricular
Lead

Right Ventricular
Lead

• LV lead site: lateral = posterior > apical
• OptiVol thoracic impedance (MID-HeFT study): 和PCWP成反比
Thank You for Your Attention!
Have a Nice Weekend~

心臟植入性電子儀器(CIED)的基本原理及設定

  • 1.
  • 2.
    Outlines • Introduction ofCIEDs (cardiovascular implantable electronic devices) • General Setting of PPM – Pacing, sensing, capture – Low rate, upper rate – Pacing mode – Refractory and blanking period – Other setting
  • 3.
  • 4.
    Cardiac Conduction Review Atria SAnode Ventricles AV node Bundle branches
  • 5.
    Implantable Pacemaker System Leadwire(s) Implantable pulse generator (IPG) • Battery • Circuitry • Connector(s) Connector Block Circuitry Battery Myocardial tissue
  • 6.
    Lead Characterization Passive FixationLeads Active Fixation Leads Epicardial Leads Bipolar coaxial lead
  • 7.
    Characteristics of anElectrical Circuit • Voltage (V) – Voltage is the force, or “push,” that causes electrons to move through a circuit – Provided by the pacemaker battery • Current (I) – Determined by the amount of electrons that move through a circuit – Cause myocardial cells to depolarize • Impedance (R or W) – The opposition to current flow – All resistance: conductor, electrode, myocardium V I R
  • 8.
  • 9.
  • 10.
    Voltage and CurrentFlow Electrical Analogies Spigot (voltage) turned up, lots of water flows (high current drain) Water pressure in system is analogous to voltage – providing the force to move the current Spigot (voltage) turned low, little flow (low current drain)
  • 11.
    Lead Impedance, 300~1500Ohm High impedance Conductor failure, impedance >2500 Ohm Low impedance Insulation defect, Impedance <300 Ohm
  • 12.
    The Revised NASPE/BPEGGeneric (NBG) Code for Antibradycardia Pacing I II III IV V Chamber(s) Paced Chamber(s) Sensed Response to Sensing Rate Modulation Multisite Pacing O = None O = None O = None O = None O = None A = Atrium A = Atrium T = Triggered R = Rate A = Atrium V = Ventricle V = Ventricle I = Inhibited D = Dual (A + V) D = Dual (A + V) D = Dual (T + I) modulation V = Ventricle D = Dual (A + V) S = Single (A or V) S = Single (A or V) NASPE is the North American Society of Pacing and Electrophysiology BPEG is the British Pacing and Electrophysiology Group BERNSTEIN, et al.; PACE 2002; 25:260–264
  • 13.
    Which mode isappropriate? Indication • DDD(R) • complete AV block • sinus nodal dysfunction • paroxysmal atrial fibrillation • AAI(R) • sinus nodal dysfunction • VVI(R) • permanent atrial fibrillation AAI/AAIR DDD/DDDR VVI/VVIR
  • 14.
    Optimal Pacing Modein Sinus Node Disease and AV Block 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy
  • 15.
  • 16.
    General Setting ofPacemaker Parameter Base Rate Description Pacing timing cycle Maximum Sensor Rate (MSR) is the Max. highest pacing rate Sensor rate allowed by ratemodulated pacing Max Tracking Rate upper limit of the ventricular pacing rate in response to the patient’s intrinsic atrial activity Setting Recommendation •Depends on patient’s need Hysteresis •Nominal setting 60-70 bpm Rest rate •Depends on patient’s age and activity (220-Age)X0.85 •Depends on patient’s age and activity (220-Age)X0.85 •Also has to consider the other cardiac disease
  • 17.
    General Setting ofPacemaker Parameter Description Setting • AVB : 200-150 • SSS : depends on the AV conductivity, nominal less than 300ms Recommendation Reduce unnecessary ventricular pacing  VIP/AICS/AV hysteresis /MVP AV/PV delay AV : internal of Ap to Vp PV : interval of As to Vp Rate responsive AV/PV delay shorten AV/PV Delay when the atrial rate is higer then 90 bpm, to mimic physical Off, slow, mid, high demand, also allows setting higher MTR Pulse Amplitude, Pulse width (A, V) determines how much electrical potential is applied to the myocardium during the pacing stimulus Nominal setting [email protected] • 2-3 times of threshold to secure capture • AutoCapture A/V sensitivity This parameter determines the amplitude of signals to which the device’s sense amplifiers will respond • A : 0.5~1.0 mV • V : 2~3 mV Higher level indicate less sensitive to P/R wave
  • 18.
    Pacemaker Code • Veryuseful in helping you understand how the IPG is interpreting events • Code: – AS  Atrial Sense – AP  Atrial Pace – AR  Atrial Refractory – VS  Ventricular Sense – VP  Ventricular Pace – VR  Ventricular Refractory
  • 19.
  • 20.
  • 21.
  • 22.
    Output Pulse ofPacemaker
  • 23.
    Pacing Threshold Pulse Amplitudeand Width (Duration) No Capture! No Capture!
  • 24.
  • 25.
  • 26.
  • 27.
  • 28.
    Lower rate, Restrate, Upper rate
  • 29.
    Lower Rate Interval(LRI) - VVI • The lowest rate the pacemaker will pace the heart in the absence of intrinsic events LRI LRI
  • 30.
    Hysteresis • Allows therate to fall below the programmed lower rate following an intrinsic beat 60 bpm 50 bpm
  • 31.
    Rest Rate • Allowsthe pacemaker to decrease the base rate to • • the programmed auto rest rate during periods of inactivity. People spend about 7 hours, out of a 24 hour day, sleeping, therefore 29% of the time is spent sleeping. The pacemaker calculates where this 29% would occur based on the Activity Variance Histogram and establishes this point as threshold.
  • 32.
    “R” = RateResponse • When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output.
  • 33.
  • 34.
    Rate-Adaptive Pacing: Accelerometer Accelerometer • • • • • • Lowcurrent drain Easy to manufacture Rapid response to onset of activity Compatible with standard pacing leads Not responsive to pressure applied to can Used in all current St. Jude Medical pacemakers (began with Trilogy DR+) Circuit Board
  • 35.
    Rate-Adaptive Pacing • TheSensors—Physiology – Evoked response • The QRS depolarization decreases in area with exercise • Works only when the device is pacing – QT interval • QT interval shortens with exercise • Works only when the device is pacing
  • 36.
    Rate-Adaptive Pacing: St.Jude • Reactive time and recovery time
  • 37.
    Upper Rate Response •Dual-chambers pacemakers try to maintain 1:1 AV synchrony but this is not always possible • In the presence of high intrinsic atrial rates, pacemakers may revert to upper rate responses
  • 38.
    Upper Sensor Rate •Defines the shortest interval (highest rate) the pacemaker can pace as dictated by the sensor (AAIR, VVIR modes)
  • 39.
  • 40.
    Upper Tracking Rate(UTR) • The maximum rate the ventricle can be paced in response to sensed atrial events Lower Rate Interval { Upper Tracking Rate Limit SAV AS VP VA SAV AS VA VP DDDR 60 / 100 (upper tracking rate) Sinus rate: 100 bpm
  • 41.
    Upper Rate Behavior VentricularRate UTR LR 1:1 Atrial Tracking No Ventricular Pacing LR = Ventricular Pacing Wenckebach UTR Atrial Rate TARP 2:1 Block
  • 42.
  • 43.
    2:1 Block DDD /60 / 120 / 310
  • 44.
    Upper Rate Behavior– 2:1 Block
  • 45.
    Wenckebach vs. 2:1Block • If the upper tracking rate interval is longer than the TARP, the pacemaker will exhibit Wenckebach behavior first. • If the TARP (total atrial refractory period) is longer than the upper tracking rate interval, then 2:1 block will occur.
  • 46.
  • 47.
  • 48.
  • 49.
  • 50.
    Benefits of DualChamber Pacing • Provides AV synchrony – Lower incidence of atrial fibrillation – Lower risk of systemic embolism and stroke – Lower incidence of new congestive heart failure – Lower mortality and higher survival rates
  • 51.
    The Magnet Test(VOO Mode)
  • 53.
  • 54.
    Magnet ECG –Medtronic
  • 55.
  • 56.
    Blanking and RefractoryPeriods • Blanking Period – A period of time during which the sense amplifiers are off, and the pacemaker is “blind”. – Designed to prevent oversensing pacing stimulus • Refractory Period – A period of time during which sensed events are ignored for timing purposes, but included in diagnostic counters – Designed to prevent inhibition by cardiac or noncardiac events
  • 57.
    Why Do WeUse Refractory and Blanking Periods? • Pacemaker sensing occurs when a signal is large enough to cross the sensing threshold 5.0 mV Sensing does not tells us anything about the origin or morphology of the sensed event, only its “size.” 2.5 mV 1.25 mV 1.25 mV Sensitivity Time
  • 58.
    Why Do WeUse Refractory and Blanking Periods? • By manipulating the sense amplifiers, we filter signals based on their relationship The potential for digitizing these signals may someday allow pacemakers to discriminate signals based on morphology rather than just on their relationship. 5.0 mV 2.5 mV SENSE! 1.25 mV Sensing Blanking Time Refractory
  • 59.
    Blanking Periods • AtrialBlanking (AB) – A non-programmable atrial blanking period (50-100 ms) from atrial paces or senses. – Avoid the atrial lead sensing its own pacing pulse or P wave (intrinsic or captured). • Ventricular blanking (VB) – 50-100 ms in duration and is dynamic, based on signal strength. – After a ventricular paced or sensed event to avoid sensing the ventricular pacing pulse or the R wave (intrinsic or captured). • Post ventricular atrial blanking (PVAB) – Initiated by a ventricular pace or sensed event (220 ms) – Avoid the atrial lead sensing the far-field ventricular output pulse or R wave.
  • 60.
    Ventricular Blanking • Thefirst portion of the refractory period • Pacemaker is “blind” to any activity • Designed to prevent oversensing pacing stimulus Lower Rate Interval VP Blanking Period Refractory Period VP VVI / 60
  • 61.
    Blanking Periods Ventricular Refractoryand Blanking Periods PVAB ARP Post Atrial Ventricular Blanking PVARP VRP Ventricular Refractory Period Ventricular Blanking
  • 62.
    AV Crosstalk • Atrialpacing spike will be detected in the ventricle. • Will inhibit ventricular pacing
  • 63.
    Add PAVB toPrevent AV Crosstalk
  • 64.
    Blanking Periods Atrial Refractoryand Blanking Periods Post Ventricular Atrial Blanking Atrial Blanking PVAB ARP PVARP VRP Atrial Refractory Period Post Ventricular Atrial Refractory Period
  • 65.
    Refractory Periods • VRPand PVARP are initiated by sensed or paced ventricular events. – The VRP is intended to prevent self-inhibition such as sensing of T-waves. – The PVARP is intended primarily to prevent sensing of retrograde P waves, far-field R wave, or premature atrial contractions.
  • 66.
    Ventricular Refractory Period 1000ms 1000 ms VRP 320 ms Blanking V P VRP 320 ms V R V P Refractory • Pacemaker VRP avoids the sensing of : – – – – – Its own stimulus The paced QRS complex The T wave (Excessive) afterpotential The combination of T wave and afterpotential V R
  • 67.
  • 68.
    Evaluation of RetrogradeVA Conduction PVARP
  • 69.
    Prevention of PMT •Prevention – Extend PVARP (Post Ventricular Atrial Refractory Period) – Program PVARP 50 ms longer than measured retrograde VA conduction (RVAC) • Use VVIR mode to determine the RVAC
  • 70.
  • 71.
  • 72.
    The 4 FundamentalTiming Cycle of a DDD Pacemaker
  • 73.
    AV Delay orAV Interval (AVI) • AVI is the interval between an atrial event (either sensed or paced) and the scheduled delivery of a ventricular stimulus. • Typical sAVI is 30-50 ms shorter than pAVI (sAVI < pAVI). • The AV intervals may be programmed to fixed values or rate-adaptive (i.e. shortening with increasing atrial rates).
  • 74.
    The Rate-Adaptive Interval •The rate-adaptive AV interval mimics the physiologic response of the heart.
  • 75.
    The 4 FundamentalTiming Cycle of a DDD Pacemaker
  • 76.
  • 77.
    Automatic Mode Switching(AMS) • AMS turns off atrial tracking in the presence of intrinsic atrial activity above a programmable atrial rate cutoff. • Mode will switch from tracking mode (DDDR, DDD) to DDIR (non-tracking mode) when atrial arrhythmia is detected. • AMS can cause a sudden rate decrease as atrial tracking. • Ventricular pacing is decoupled from atrial events, but rate responsive pacing is matched to metabolic needs.
  • 78.
    Mode Switch • Thedevice detects an atrial arrhythmia by constantly comparing intervals with the programmed mode switch detection rate. MS DDD / 60 / 120 Mode Switch ON
  • 79.
    減少右心室電刺激 = 減少心衰竭住院 及心房顫動 Riskof AF Relative to DDDR Patient With Cum%VP=0 MOST study Every incremental 1% of unnecessary VP increases the risk for Heart Failure Hospitalizations by 5.4% There is a 1% increase in the risk of AF for each 1% increase in cumulative right ventricular pacing. Within 95% Confidence Risk of AF Cumulative % Ventricular Pacing
  • 80.
    Ventricular Intrinsic Preference(VIP) • VIP activation – Device extends AV delays by 160 ms searching for Rwaves for up to 3 cycles in our example – R-waves found within 1 cycle, therefore, AV delay remains at lengthened value
  • 81.
    Ventricular Intrinsic Preference(VIP) • VIP deactivation – Device extends AV delays by 160 ms searching for Rwaves for up to 3 cycles in our example – No R-waves found within 3 cycle, therefore, AV delays returns to programmed values. 1 2 3
  • 82.
    Ventricular Intrinsic Preference(VIP) • VIP most beneficial – – Intermittent AV block Mild prolongation of AV conduction • VIP not beneficial – – – Complete permanent AV block Marked 1st degree AV block If CRT therapy is indicated • VIP clinical benefits – Less risk of heart failure progression – Less risk of developing AF – Better QoL trough improved hemodynamics
  • 83.
    MVP AAI (R)to DDD(R)Pacing (MVP) Managed Ventricular Operation Switch from AAI(R) to Temporary DDD(R) Mode Ventricular support if loss of A-V conduction is persistent. 2 out of 4 Most Recent A-A Intervals with No Conducted VS Event No VS Conduction Ventricular Back-Up Pace at 80 ms Post the Scheduled AP Switch to DDD(R) occurs after back-up VP; programmed PAV/SAV are used during this mode of operation
  • 84.
    Intracardiac Defibrillator (ICD) DualCoil Lead Single Coil Lead Cold Can Proximal Shock Electrode Hot Can Distal Shock Electrode
  • 85.
    Cardiac Resynchronization Therapy Goal:Mitigate dyssynchrony through atrial synchronous biventricular pacing Right Atrial Lead Left Ventricular Lead Right Ventricular Lead • LV lead site: lateral = posterior > apical • OptiVol thoracic impedance (MID-HeFT study): 和PCWP成反比
  • 86.
    Thank You forYour Attention! Have a Nice Weekend~