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Pacemaker Timing Part I

Pacemaker Timing Part I. Pacemaker Timing. 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

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Pacemaker Timing Part I

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  1. Pacemaker TimingPart I

  2. Pacemaker Timing

  3. 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

  4. Timing Intervals Are Expressed in Milliseconds • One millisecond = 1 / 1,000 of a second

  5. Converting Rates to Intervals 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

  6. NBG Code Review I II III IV V Programmable Antitachy Chamber Chamber Response Paced Sensed to Sensing Functions/Rate Function(s) Modulation P: Simple programmable V: Ventricle V: Ventricle T: Triggered P: Pace M: Multi- programmable A: Atrium A: Atrium I: Inhibited S: Shock D: Dual (A+V) D: Dual (T+I) D: Dual (P+S) D: Dual (A+V) C: Communicating O: None O: None O: None O: None R: Rate modulating S: Single (A or V) S: Single (A or V) O: None

  7. Single-Chamber Timing

  8. Single Chamber Timing Terminology • Lower rate • Refractory period • Blanking period • Upper rate

  9. VP VP Lower Rate Interval • Defines the lowest rate the pacemaker will pace Lower Rate Interval VVI / 60

  10. VP VP Refractory Period Refractory Period • Interval initiated by a paced or sensed event • Designed to prevent inhibition by cardiac or non-cardiac events Lower Rate Interval VVI / 60

  11. VP VP Blanking Period • The first portion of the refractory period • Pacemaker is “blind” to any activity • Designed to prevent oversensing pacing stimulus Lower Rate Interval VVI / 60 Blanking Period Refractory Period

  12. VP VP Upper Sensor Rate Interval • Defines the shortest interval (highest rate) the pacemaker can pace as dictated by the sensor (AAIR, VVIR modes) Lower Rate Interval Upper Sensor Rate Interval VVIR / 60 / 120 Blanking Period Refractory Period

  13. Single Chamber Mode Examples

  14. VP VP Blanking Period VOO Mode • Asynchronous pacing delivers output regardless of intrinsic activity Lower Rate Interval VOO / 60

  15. VP VS VVI Mode • Pacing inhibited with intrinsic activity { Lower Rate Interval VP Blanking/Refractory VVI / 60

  16. VP VP VVIR • Pacing at the sensor-indicated rate Lower Rate Upper Rate Interval (Maximum Sensor Rate) Refractory/Blanking VVIR / 60/120 Rate Responsive Pacing at the Upper Sensor Rate

  17. AP AP AAIR • Atrial-based pacing allows the normal A-V activation sequence to occur Lower Rate Interval Upper Rate Interval (maximum sensor rate) Refractory/Blanking AAIR / 60 / 120 (No Activity)

  18. Other Single Chamber Operations

  19. Hysteresis • Allows the rate to fall below the programmed lower rate following an intrinsic beat Lower Rate Interval-60 ppm Hysteresis Rate-50 ppm VP VP VP VS

  20. Noise Reversion • Continuous refractory sensing will cause pacing at the lower or sensor driven rate Lower Rate Interval Noise Sensed SR SR SR SR VP VP VVI/60

  21. Dual-Chamber Timing

  22. 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

  23. Benefits 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

  24. AP AP VP VP Four “Faces” of Dual Chamber Pacing • Atrial Pace, Ventricular Pace (AP/VP) AV V-A AV V-A Rate = 60 bpm / 1000 ms A-A = 1000 ms

  25. AV V-A AV V-A AP AP VS VS Four “Faces” of Dual Chamber Pacing • Atrial Pace, Ventricular Sense (AP/VS) Rate = 60 ppm / 1000 ms A-A = 1000 ms

  26. V-A AV V-A AV Four “Faces” of Dual Chamber Pacing • Atrial Sense, Ventricular Pace (AS/ VP) AS AS VP VP Rate (sinus driven) = 70 bpm / 857 ms A-A = 857 ms

  27. AV V-A AV V-A AS AS VS VS Four “Faces” of Dual Chamber Pacing • Atrial Sense, Ventricular Sense (AS/VS) Rate (sinus driven) = 70 bpm / 857 ms Spontaneous conduction at 150 ms A-A = 857 ms

  28. Dual Chamber Timing Parameters • Lower rate • AV and VA intervals • Upper rate intervals • Refractory periods • Blanking periods

  29. Lower Rate • The lowest rate the pacemaker will pace the atrium in the absence of intrinsic atrial events Lower Rate Interval AP AP VP VP DDD 60 / 120

  30. SAV PAV 200 ms 170 ms AP AS VP VP AV Intervals • Initiated by a paced or non-refractory sensed atrial event • Separately programmable AV intervals – SAV /PAV Lower Rate Interval DDD 60 / 120

  31. Atrial Escape Interval (V-A Interval) Lower rate interval – AV interval V-A interval

  32. AP AP VP VP Atrial Escape Interval (V-A Interval) • The interval initiated by a paced or sensed ventricular event to the next atrial event Lower Rate Interval 800 ms 200 ms VA Interval AV Interval DDD 60 / 120 PAV 200 ms; V-A 800 ms

  33. AP AP VP VP Upper Activity (Sensor) Rate • In rate responsive modes, the Upper Activity Rate provides the limit for sensor-indicated pacing Lower Rate Limit Upper Activity Rate Limit PAV V-A PAV V-A DDDR 60 / 120 A-A = 500 ms

  34. AS AS VP VP Upper Tracking Rate • The maximum rate the ventricle can be paced in response to sensed atrial events { Lower Rate Interval Upper Tracking Rate Limit SAV SAV VA VA DDDR 60 / 100 (upper tracking rate) Sinus rate: 100 bpm

  35. 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 AP A-V Interval (Atrial Refractory) Post Ventricular Atrial Refractory Period (PVARP) VP Ventricular Refractory Period (VRP)

  36. Blanking Periods • First portion of the refractory period-sensing is disabled AP AP VP Atrial Blanking (Nonprogrammable) Post Ventricular Atrial Blanking (PVAB) Ventricular Blanking (Nonprogrammable) Post Atrial Ventricular Blanking

  37. General Medtronic Pacemaker Disclaimer INDICATIONS 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.

  38. 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.

  39. Continued inPacemaker Timing Parts II and III

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