CorePace Module 7 - Advanced Pacemaker Operations by dandanhuanghuang

VIEWS: 72 PAGES: 43

									Advanced Pacemaker Operations
           Module 7




                                1
Objectives

• Define: Blanking and refractory
• Complete VVI and DDD timing diagrams
  – Correctly identifying PVARP, PVAB, PPAB, and TARP
  – Identify events in refractory and blanking, and their effect on timing
  – Correctly identify Marker Channel™ notations
• Identify upper rate behaviors
  – Calculate 2:1 vs. Wenckebach rates




                                                                             2
                    ™
Marker Channel

• Very useful in helping you understand how the IPG is
  interpreting events
• Each manufacturer has its own code
• Medtronic’s code:
  – AS  Atrial Sense
  – AP  Atrial Pace
  – AR  Atrial Refractory
  – VS  Ventricular Sense
  – VP  Ventricular Pace
  – VR  Ventricular Refractory


                                                         3
What Do You Think Would Happen Next If…

• The QRS was sensed by the atrial channel?

     A    A
     P    S




DDD 60
         V              Note: The Marker Channel tells you how
         P
                        the pacemaker is interpreting these
                        events.
 Click for Answer
The next atrial pace would be inhibited because the pacemaker
thinks the QRS is a P-wave.
Obviously, this is not how we want a DDD pacemaker to behave.
This was a problem in early pacemakers.
                                                                 4
What Do You Think Would Happen Next If…

• These T-waves were sensed by the ventricular
  channel?
                         Actual Rate: 50 bpm or 1200 ms




Programmed: VVI 60
                     V         V                          V   V
                     P         S                          P   S
 Click for Answer




                                                                  5
Blanking and Refractory Periods

• Blanking Period
  – A period of time during which the sense amplifiers are off, and the
    pacemaker is “blind”
  – Some blanking periods are programmable, some are non-
    programmable


• Refractory Period
  – A period of time during which sensed events are ignored for timing
    purposes, but included in diagnostic counters
  – Some refractory periods are programmable, some non-
    programmable



                                                                          6
Why Do We Use Refractory and Blanking Periods?

• Pacemaker sensing occurs when a signal is large enough
  to cross the sensing threshold



  Sensing does not tells us                        5.0 mV
  anything about the origin or
  morphology of the sensed                         2.5 mV
  event, only its “size.”
                                                   1.25 mV
              1.25 mV Sensitivity

                                      Time




                                                             7
Why Do We Use Refractory and Blanking Periods?

• By manipulating the sense amplifiers, we filter signals
  based on their relationship



   The potential for digitizing                                      5.0 mV
   these signals may
   someday allow                                                     2.5 mV
                                  SENSE!
   pacemakers to discriminate
   signals based on                                                  1.25 mV
   morphology rather than just
   on their relationship.

                                  Sensing   Blanking    Refractory
                                                 Time

                                                                               8
Let’s Look at the VVI Example Again…

• Now, is the T-wave sensed by the ventricular channel?




VVI 60                     V      V
                                                       V      V
                           P      R                           R
                                                       P

Click for Answer

The T-wave falls in the ventricular refractory period (VR), and it is
ignored for timing purposes.

The VVI pacemaker is operating normally.

                                                                        9
VVI Timing

• Note the addition of the Blanking and Refractory periods


       1000 ms                        1000 ms


                         VRP 320 ms                  VRP 320 ms


                     V         V                     V     V
       Blanking
                     P         R                     P     R
                                        Refractory



  The pacemaker applies these
  periods to every timing cycle.


                                                                  10
T-wave Sensing

• Is there another way to program the pacemaker to ignore
  the T-waves?
  Click for Answer



        1000 ms                          1000 ms


                            VRP 320 ms                  VRP 320 ms


                        V        V                      V     V
           Blanking     P        R                      P     R
                                           Refractory

  We could program the pacemaker to be less sensitive (e.g., from
  2.5mV to 5.0 mV). But then it might not sense every R-wave.

                                                                     11
Dual Chamber Timing

Refractory and Blanking Periods

            PVAB
                PVARP
                              Those affecting the atrial
   ARP
                              channel are indicated above
                              the ECG baseline.


               VRP
                              Those affecting the ventricular
                              channel are indicated below
                              the ECG baseline.


                              Red: Blanking
                              Orange: Refractory period


                                                                12
Dual Chamber Timing
                                             Post Ventricular
• Atrial Refractory and                      Atrial Blanking
  Blanking Periods

                          PVAB
   Atrial
                   ARP      PVARP
  Blanking

                           VRP



                                    Post Ventricular Atrial
       Atrial                         Refractory Period
     Refractory
      Period


                                                                13
Dual Chamber Timing

• Ventricular Refractory and Blanking Periods

                             PVAB
                    ARP          PVARP


                               VRP
   Post Atrial
   Ventricular
    Blanking                         Ventricular Refractory
                                             Period


                                Ventricular
                                 Blanking



                                                              14
Dual Chamber Timing

 • Atrial Pace (AP) - Ventricular Pace (VP) example

                    A-A interval                A-A interval
DDD 60
                    V-A interval                    V-A interval
          PAV                          PAV


                PVAB                         PVAB
          ARP          PVARP          ARP           PVARP

                  VRP                          VRP




   The pacemaker applies these periods every timing cycle.

                                                                   15
Dual Chamber Timing

• Lower Rate (A-A) Interval
  – A-A interval indicates the minimum rate the device will pace under
    normal circumstances (“escape interval,” “lower rate interval”)
  – In dual chamber pacemakers we subdivide this into the A-V interval
    (PAV or SAV) and the V-A interval
     • Normally, the device is designed to always use A-A timing – to maintain
       a steady atrial rate

                          A-A interval                A-A interval

                              V-A interval                 V-A interval
                 PAV                         PAV


                       PVAB                        PVAB
                 ARP            PVARP        ARP           PVARP

                         VRP                         VRP




                                                                                 16
Dual Chamber Timing

• Upper Tracking Rate (UTR)
  – The maximum rate the ventricles will be paced 1:1 in response to
    atrial sensed events

                  A-A interval                A-A interval

                  V-A interval                V-A interval
        SAV                      SAV
                      UTR                        UTR


               PVAB                    PVAB
        ARP             PVARP    ARP           PVARP

                  VRP                    VRP




                                                                       17
Dual Chamber Timing

• Tracking
  – 1:1 tracking (atrial sense – ventricular pace) occurs at rates above
    the Lower Rate, but below the Upper Tracking Rate


                        A-A interval                      A-A interval

                        UTR


                PVAB
          ARP            PVARP

                  VRP



                                        1:1 tracking of
                                       any atrial sense




                                                                           18
Dual Chamber Timing

• The pacemaker’s response to high atrial rates
  – To a pacemaker, an increase in atrial rate means that V-A intervals
    are getting shorter

                        A-A interval                    A-A interval

                         V-A interval                    V-A interval
          SAV                             SAV

                        UTR                             UTR


                PVAB                            PVAB

                         PVARP            ARP           PVARP
          ARP

                  VRP                             VRP




 In other words, the next atrial sense is getting closer to the previous
 ventricular event.

                                                                           19
Dual Chamber Timing
  Upper Rate Behavior




                        20
Upper Rate Behavior

• Pacemaker Wenckebach
  – Caused by the atrial rate exceeding the Upper Tracking Rate




                                                                  21
Upper Rate Behavior

    • Pacemaker Wenckebach
      – Prolongs the SAV until upper rate limit expires
      – Produces gradual change in tracking rate ratio


          A-A interval
                                        A-A interval                A-A interval

                      UTR                   UTR                                 UTR

A                        A                     A          A
S                        S                     R          P
    ARP       PVARP          ARP       PVARP                  ARP       PVARP

    SAV                      SAV                              PAV
          V                        V                                V
          P                        P                                P

                                                                                      22
Wenckebach Example

• Pacemaker patient on an exercise test
  – 4:3 Wenckebach operation
    • Each AS (P-wave) is followed by an increasing SAV, and then the VP
    • Eventually an atrial beat is not tracked, and a ventricular beat is dropped




                                                                                    23
Wenckebach Example



                     This P-wave fell in the
                     PVARP of the previous
                     cycle.
                     It is refractory (AR), so it
                     is ignored for timing.
                     It cannot start an SAV, so
                     it is not followed by a
                     ventricular pace.
                     This is normal upper rate
                     pacemaker behavior.




                                                    24
Upper Rate Behavior

    • 2:1 Block
      – Occurs when P-waves are faster than TARP
      – TARP = SAV + PVARP


    ARP         PVARP               ARP         PVARP           ARP

              TARP                            TARP               TARP
A                       A       A                       A   A
S                       R       S                       R   S

    SAV                             SAV                         SAV
          V                               V                           V
          P                               P                           P




                                                                          25
Upper Rate Behavior

• 2:1 Block
  – Caused by the atrial rate exceeding the Total Atrial Refractory
    Period (TARP)




                                                                      26
Knowledge Check

• Given the following          • Given the same pacemaker
  pacemaker parameters, what     parameters, what atrial rate
  rhythm will result from an     would result in 2:1 block?
  atrial rate of 130 bpm?
  – UTR = 120 bpm                Click for Answer
  – SAV = 150 ms
                                  – An atrial rate above 150 bpm
  – PVARP = 250 ms

  Click for Answer

  – Pacemaker Wenckebach




                                                                   27
Upper Rate Behavior
                   UTR
Ventricular Rate




                    LR
                                             1:1 Atrial      Wenckebach    2:1 Block
                             No
                                             Tracking
                          Ventricular
                           Pacing


                                        LR                UTR           TARP
                                                          Atrial Rate
                    = Ventricular Pacing

                                                                                       28
Upper Rate Behavior
                   UTR
Ventricular Rate




                    LR
                                             1:1 Atrial      Wenckebach    2:1 Block
                             No
                                             Tracking
                          Ventricular
                           Pacing


                                        LR                UTR           TARP

                    = Ventricular Pacing                  Atrial Rate

                                                                                       29
Achieving a Higher UTR without Block

• Decrease SAV                      • Decrease PVARP
    ARP     PVARP                          ARP     PVARP

          TARP                                   TARP
A                   A                  A                   A
S                   R                  S                   R

    SAV                                    SAV



 ARP      PVARP         Increased          ARP    PVARP         Increased
       TARP              Tracking            TARP                Tracking
A                   A                  A                   A
S                   S                  S                   S

 SAV                SAV                    SAV                 SAV



                                                                            30
Achieving a Higher UTR without Block

• SAV and PVARP managed automatically
  – Programming Rate-Adaptive AV to “On”
    • This will automatically decrease the SAV/PAV as the atrial rate
      increases

  – Programming PVARP to “Auto”
    • This will automatically decrease the PVARP as the atrial rate increases




                                                                                31
If Long TARP is the Problem…
• Why not just program short AV Intervals or short PVARP?
  – Short AV intervals may force ventricular pacing
  – Short PVARP may allow retrograde conduction to be sensed
     • Consider this ECG:


                                                 • The retrograde P-waves
                                                   occur outside of PVARP.
                                                 • The pacemaker tracks
                                                   the retrograde P-waves.
                                                 • This is called a
                                                   Pacemaker Mediated
                                                   Tachycardia (PMT).




                                                                             32
Status Check
Can you identify the following
Marker Channel notations?

  Click for Answer

            AS            An Atrial Sense (P-wave)
            VR            Ventricular Refractory
            AR            Atrial Refractory
            AP            Atrial Pace
            VP            Ventricular Pace
            VS            A Ventricular Sense (QRS or
                           R-wave)
                                                        33
Status Check
Can you complete this timing diagram?



 Click for Answer


   Lower Rate Interval       Lower Rate Interval



                             VRP                       VRP
         V. Blanking                 V. Blanking
                         V                         V
                         P                         P




                                                             34
Status Check
 Complete this timing diagram
• Show:
    - Atrial Refractory during the AV Interval   Atrial Refractory during the AV Interval
    - PVARP with PVAB                            PVARP with PVAB
    - VRP                                        VRP




 Click for Answer

                                                                                        35
Status Check

• You are called to evaluate this rhythm strip
  – Obtained while the patient is having an exercise test
  – Clinician thinks it is loss of capture
  – Patient’s underlying rhythm is CHB
• What is going on?




                            2:1 block. P-waves
Click for Answer


                                                            36
Status Check

• What mode do you think this is?
• Calculate the Atrial and Ventricular rates
• Propose a programming solution to resolve this
                     430 ms                   860 ms




Click for Answer   DDD Mode. Atrial rate: 430 ms or 140 bpm, Ventricular
                   rate: 860 ms or 70 bpm.
                   Increase the UTR and program RA-AV on, or Increase
                   UTR and decrease PVARP.

                                                                           37
Status Check

• Given the following parameters, what will occur first as the
  patient’s atrial rate increases? Wenckebach or 2:1 block?
   – Upper Tracking Rate: 120 bpm
   – SAV = 200 ms
   – PVARP = 350 ms

Click for Answer



• 2:1 block will occur first




                                                                 38
Brief Statements
Indications
•   Implantable Pulse Generators (IPGs) are indicated for rate adaptive pacing in patients who ay benefit from increased
    pacing rates concurrent with increases in activity and increases in activity and/or minute ventilation. 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.
•   Implantable cardioverter defibrillators (ICDs) are indicated for ventricular antitachycardia pacing and ventricular
    defibrillation for automated treatment of life-threatening ventricular arrhythmias.
•   Cardiac Resynchronization Therapy (CRT) ICDs are indicated for ventricular antitachycardia pacing and ventricular
    defibrillation for automated treatment of life-threatening ventricular arrhythmias and for the reduction of the symptoms of
    moderate to severe heart failure (NYHA Functional Class III or IV) in those patients who remain symptomatic despite
    stable, optimal medical therapy and have a left ventricular ejection fraction less than or equal to 35% and a QRS
    duration of ≥130 ms.
•   CRT IPGs are indicated for the reduction of the symptoms of moderate to severe heart failure (NYHA Functional Class
    III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy, and have a left ventricular
    ejection fraction less than or equal to 35% and a QRS duration of ≥130 ms.
Contraindications
•   IPGs and CRT IPGs are contraindicated for 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; and certain IPGs are contraindicated for use with epicardial leads and with abdominal
    implantation.
•   ICDs and CRT ICDs are contraindicated in patients whose ventricular tachyarrhythmias may have transient or
    reversible causes, patients with incessant VT or VF, and for patients who have a unipolar pacemaker. ICDs are also
    contraindicated for patients whose primary disorder is bradyarrhythmia.




                                                                                                                                  39
Brief Statements (continued)
Warnings/Precautions
• Changes in a patient’s disease and/or medications may alter the efficacy of the device’s programmed
  parameters. Patients should avoid sources of magnetic and electromagnetic radiation to avoid
  possible underdetection, inappropriate sensing and/or therapy delivery, tissue damage, induction of an
  arrhythmia, device electrical reset or device damage. Do not place transthoracic defibrillation paddles
  directly over the device. Additionally, for CRT ICDs and CRT IPGs, certain programming and device
  operations may not provide cardiac resynchronization. Also for CRT IPGs, Elective Replacement
  Indicator (ERI) results in the device switching to VVI pacing at 65 ppm. In this mode, patients may
  experience loss of cardiac resynchronization therapy and / or loss of AV synchrony. For this reason,
  the device should be replaced prior to ERI being set.
Potential complications
• Potential complications include, but are not limited to, rejection phenomena, erosion through the skin,
  muscle or nerve stimulation, oversensing, failure to detect and/or terminate arrhythmia episodes, and
  surgical complications such as hematoma, infection, inflammation, and thrombosis. An additional
  complication for ICDs and CRT ICDs is the acceleration of ventricular tachycardia.
• See the device manual for detailed information regarding the implant procedure, indications,
  contraindications, warnings, precautions, and potential complications/adverse events. For further
  information, please call Medtronic at 1-800-328-2518 and/or consult Medtronic’s website at
  www.medtronic.com.
Caution: Federal law (USA) restricts these devices to sale by or on the order of a physician.




                                                                                                            40
Brief Statement: Medtronic Leads
Indications
• Medtronic leads are used as part of a cardiac rhythm disease management system. Leads are
  intended for pacing and sensing and/or defibrillation. Defibrillation leads have application for patients
  for whom implantable cardioverter defibrillation is indicated
Contraindications
• Medtronic leads are contraindicated for the following:
• ventricular use in patients with tricuspid valvular disease or a tricuspid mechanical heart valve.
• patients for whom a single dose of 1.0 mg of dexamethasone sodium phosphate or dexamethasone
  acetate may be contraindicated. (includes all leads which contain these steroids)
• Epicardial leads should not be used on patients with a heavily infracted or fibrotic myocardium.
• The SelectSecure Model 3830 Lead is also contraindicated for the following:
• patients for whom a single dose of 40.µg of beclomethasone dipropionate may be contraindicated.
• patients with obstructed or inadequate vasculature for intravenous catheterization.




                                                                                                              41
Brief Statement: Medtronic Leads (continued)
Warnings/Precautions
• People with metal implants such as pacemakers, implantable cardioverter defibrillators (ICDs), and
  accompanying leads should not receive diathermy treatment. The interaction between the implant and
  diathermy can cause tissue damage, fibrillation, or damage to the device components, which could
  result in serious injury, loss of therapy, or the need to reprogram or replace the device.
• For the SelectSecure Model 3830 lead, total patient exposure to beclomethasone 17,21-dipropionate
  should be considered when implanting multiple leads. No drug interactions with inhaled
  beclomethasone 17,21-dipropionate have been described. Drug interactions of beclomethasone
  17,21-dipropionate with the Model 3830 lead have not been studied.
Potential Complications
• Potential complications include, but are not limited to, valve damage, fibrillation and other arrhythmias,
  thrombosis, thrombotic and air embolism, cardiac perforation, heart wall rupture, cardiac tamponade,
  muscle or nerve stimulation, pericardial rub, infection, myocardial irritability, and pneumothorax.
  Other potential complications related to the lead may include lead dislodgement, lead conductor
  fracture, insulation failure, threshold elevation or exit block.
• See specific device manual for detailed information regarding the implant procedure, indications,
  contraindications, warnings, precautions, and potential complications/adverse events. For further
  information, please call Medtronic at 1-800-328-2518 and/or consult Medtronic’s website at
  www.medtronic.com.
Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.




                                                                                                               42
Disclosure

                               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.




                                                                      43

								
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