pacemaker timing part i
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Pacemaker TimingPacemaker TimingPart IPart I
Pacemaker TimingPacemaker Timing
Objectives:Objectives:
Describe expected pacemaker function based on the NBG code
Interpret intervals comprising single and dual chamber timing
Recognize various modes of dual chamber device operation from lower to upper rate behaviors
Calculate upper rate behavior based on programmed parameters
Identify therapy specific device operations when presented on patient ECG
Timing Intervals Are Expressed Timing Intervals Are Expressed in Millisecondsin Milliseconds
One millisecond = 1 / 1,000 of a second
Converting Rates to Intervals Converting Rates to Intervals and Vice Versa and Vice Versa
Rate to interval (ms):
– 60,000/rate (in bpm) = interval (in milliseconds)
– Example: 60,000/100 bpm = 600 milliseconds
Interval to rate (bpm):
– 60,000/interval (in milliseconds) = rate (bpm)
– Example: 60,000/500 ms = 120 bpm
NBG Code ReviewNBG Code Review
IChamber
Paced
IIChamber
Sensed
IIIResponseto Sensing
IVProgrammableFunctions/Rate
Modulation
VAntitachy
Function(s)
V: Ventricle V: Ventricle T: Triggered P: Simpleprogrammable
P: Pace
A: Atrium A: Atrium I: Inhibited M: Multi-programmable
S: Shock
D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S)
O: None O: None O: None R: Rate modulating O: None
S: Single (A or V)
S: Single (A or V)
O: None
Single-Chamber TimingSingle-Chamber Timing
Single Chamber Timing TerminologySingle Chamber Timing Terminology
Lower rate
Refractory period
Blanking period
Upper rate
Lower Rate IntervalLower Rate Interval
Lower Rate Interval
VP VP VVI / 60
Defines the lowest rate the pacemaker will pace
Refractory PeriodRefractory Period
Lower Rate Interval
VP VP VVI / 60
Interval initiated by a paced or sensed event
Designed to prevent inhibition by cardiac or non-cardiac events
Refractory Period
Blanking PeriodBlanking Period
Lower Rate Interval
VP VP VVI / 60
The first portion of the refractory period
Pacemaker is “blind” to any activity
Designed to prevent oversensing pacing stimulus
Blanking PeriodRefractory Period
Upper Sensor Rate IntervalUpper Sensor Rate Interval
Lower Rate Interval
VP VP VVIR / 60 / 120
Defines the shortest interval (highest rate) the pacemaker can pace as dictated by the sensor (AAIR, VVIR modes)
Blanking PeriodRefractory Period
Upper Sensor Rate Interval
Single Chamber Mode ExamplesSingle Chamber Mode Examples
VOO ModeVOO Mode
Blanking Period
VP VP
Lower Rate Interval
VOO / 60
Asynchronous pacing delivers output regardless of intrinsic activity
VVI ModeVVI Mode
Lower Rate Interval
VP VSBlanking/Refractory
VP
{
VVI / 60
Pacing inhibited with intrinsic activity
VVIR VVIR
VP VP
Refractory/Blanking
Lower Rate
Upper Rate Interval(Maximum Sensor Rate)
VVIR / 60/120Rate Responsive Pacing at the Upper Sensor Rate
Pacing at the sensor-indicated rate
AAIRAAIR
Lower Rate Interval
AP APRefractory/Blanking
Upper Rate Interval(maximum sensor rate)
AAIR / 60 / 120(No Activity)
Atrial-based pacing allows the normal A-V activation sequence to occur
Other Single Chamber OperationsOther Single Chamber Operations
VP VP VS VP
Lower Rate Interval-60 ppm
HysteresisHysteresis
Allows the rate to fall below the programmed lower rate following an intrinsic beat
Hysteresis Rate-50 ppm
Noise ReversionNoise Reversion
VPVPSRSR SR SR
Noise Sensed
Lower Rate Interval
VVI/60
Continuous refractory sensing will cause pacing at the lower or sensor driven rate
Dual-Chamber TimingDual-Chamber Timing
Benefits of Dual Chamber PacingBenefits 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
Benefits of Dual-Chamber PacingBenefits of Dual-Chamber Pacing
Study Results
Higano et al. 1990
Gallik et al. 1994
Santini et al. 1991
Rosenqvist et al. 1991
Sulke et al. 1992
Improved cardiac index during low levelexercise (where most patient activity occurs)
Increase in LV filling
30% increase in resting cardiac output
Decrease in pulmonary wedge pressure
Increase in resting cardiac output
Increase in resting cardiac output, especiallyin patients with poor LV function
Decreased incidence of mitral and tricuspidvalve regurgitation
Rate = 60 bpm / 1000 msA-A = 1000 ms
APVP
APVP
V-AAV V-AAV
Atrial Pace, Ventricular Pace (AP/VP)
Four “Faces” of Dual Chamber PacingFour “Faces” of Dual Chamber Pacing
Rate = 60 ppm / 1000 msA-A = 1000 ms
AP VS
AP VS
V-AAV V-AAV
Atrial Pace, Ventricular Sense (AP/VS)
Four “Faces” of Dual Chamber PacingFour “Faces” of Dual Chamber Pacing
ASVP
ASVP
Rate (sinus driven) = 70 bpm / 857 msA-A = 857 ms
Atrial Sense, Ventricular Pace (AS/ VP)
V-AAV AV V-A
Four “Faces” of Dual Chamber PacingFour “Faces” of Dual Chamber Pacing
Rate (sinus driven) = 70 bpm / 857 msSpontaneous conduction at 150 msA-A = 857 ms
ASVS
ASVS
V-AAV AV V-A
Atrial Sense, Ventricular Sense (AS/VS)
Four “Faces” of Dual Chamber PacingFour “Faces” of Dual Chamber Pacing
Dual Chamber Timing ParametersDual Chamber Timing Parameters
Lower rate
AV and VA intervals
Upper rate intervals
Refractory periods
Blanking periods
Lower Rate Interval
APVP
APVP
Lower Rate Lower Rate
The lowest rate the pacemaker will pace the atrium in the absence of intrinsic atrial events
DDD 60 / 120
APVP
ASVP
PAV SAV
200 ms 170 ms
Lower Rate Interval
AV IntervalsAV Intervals
Initiated by a paced or non-refractory sensed atrial event
– Separately programmable AV intervals – SAV /PAV
DDD 60 / 120
Atrial Escape Interval (V-A Interval)Atrial Escape Interval (V-A Interval)
Lower rate interval– AV intervalV-A interval
Lower Rate Interval
APVP
APVP
AV Interval VA Interval
Atrial Escape Interval (V-A Interval)Atrial Escape Interval (V-A Interval)
The interval initiated by a paced or sensed ventricular event to the next atrial event
DDD 60 / 120PAV 200 ms; V-A 800 ms
200 ms 800 ms
DDDR 60 / 120A-A = 500 ms
APVP
APVP
Upper Activity Rate Limit
Lower Rate Limit
V-APAV V-APAV
Upper Activity (Sensor) RateUpper Activity (Sensor) Rate
In rate responsive modes, the Upper Activity Rate provides the limit for sensor-indicated pacing
ASVP
ASVP
DDDR 60 / 100 (upper tracking rate) Sinus rate: 100 bpm
Lower Rate Interval {
Upper Tracking Rate Limit
Upper Tracking RateUpper Tracking Rate
SAV SAVVA VA
The maximum rate the ventricle can be paced in response to sensed atrial events
Post Ventricular Atrial Refractory Period (PVARP)
Refractory PeriodsRefractory 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
AP
VPVentricular Refractory Period (VRP)
A-V Interval(Atrial Refractory)
Blanking PeriodsBlanking Periods
First portion of the refractory period-sensing is disabled
AP
VP
AP
Post Ventricular Atrial Blanking (PVAB)
Post Atrial Ventricular Blanking
Ventricular Blanking (Nonprogrammable)
Atrial Blanking (Nonprogrammable)
General Medtronic Pacemaker DisclaimerINDICATIONS
Medtronic pacemakers are indicated for rate adaptive pacing in patients who may benefit from increased pacing rates concurrent with increases in activity (Thera, Thera-i, Prodigy, Preva and Medtronic.Kappa 700 Series) or increases in activity and/or minute ventilation (Medtronic.Kappa 400 Series).
Medtronic pacemakers are also indicated for dual chamber and atrial tracking modes in patients who may benefit from maintenance of AV synchrony. Dual chamber modes are specifically indicated for treatment of conduction disorders that require restoration of both rate and AV synchrony, which include various degrees of AV block to maintain the atrial contribution to cardiac output and VVI intolerance (e.g., pacemaker syndrome) in the presence of persistent sinus rhythm.
9790 Programmer
The Medtronic 9790 Programmers are portable, microprocessor based instruments used to program Medtronic implantable devices.
9462
The Model 9462 Remote Assistant™ is intended for use in combination with a Medtronic implantable pacemaker with Remote Assistant diagnostic capabilities.
CONTRAINDICATIONS
Medtronic pacemakers are contraindicated for the following applications:
Dual chamber atrial pacing in patients with chronic refractory atrial tachyarrhythmias.
Asynchronous pacing in the presence (or likelihood) of competitive paced and intrinsic rhythms.
Unipolar pacing for patients with an implanted cardioverter-defibrillator because it may cause unwanted delivery or inhibition of ICD therapy.
Medtronic.Kappa 400 Series pacemakers are contraindicated for use with epicardial leads and with abdominal implantation.
WARNINGS/PRECAUTIONS
Pacemaker patients should avoid sources of magnetic resonance imaging, diathermy, high sources of radiation, electrosurgical cautery, external defibrillation, lithotripsy, and radiofrequency ablation to avoid electrical reset of the device, inappropriate sensing and/or therapy.
9462
Operation of the Model 9462 Remote Assistant™ Cardiac Monitor near sources of electromagnetic interference, such as cellular phones, computer monitors, etc. may adversely affect the performance of this device.
See the appropriate technical manual for detailed information regarding indications, contraindications, warnings, and precautions.
Caution: Federal law (U.S.A.) restricts this device to sale by or on the order of a physician.
Medtronic Leads
For Indications, Contraindications, Warnings, and Precautions for Medtronic Leads, please refer to the appropriate Leads Technical Manual or call your local Medtronic Representative.
Caution: Federal law restricts this device to sale by or on the order of a Physician.
Note:
This presentation is provided for general educational purposes only and should not be considered the exclusive source for this type of information. At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in a particular situation.
Continued inContinued in
Pacemaker Timing Pacemaker Timing Parts II and IIIParts II and III
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