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Pacemaker Timing Part I. Pacemaker Timing Objectives: zDescribe expected pacemaker function based on the NBG code zInterpret intervals comprising single.

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Presentation on theme: "Pacemaker Timing Part I. Pacemaker Timing Objectives: zDescribe expected pacemaker function based on the NBG code zInterpret intervals comprising single."— Presentation transcript:

1 Pacemaker Timing Part I

2 Pacemaker Timing

3 Objectives: zDescribe expected pacemaker function based on the NBG code zInterpret intervals comprising single and dual chamber timing zRecognize various modes of dual chamber device operation from lower to upper rate behaviors zCalculate upper rate behavior based on programmed parameters zIdentify therapy specific device operations when presented on patient ECG

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

5 Converting Rates to Intervals and Vice Versa zRate to interval (ms): –60,000/rate (in bpm) = interval (in milliseconds) –Example: 60,000/100 bpm = 600 milliseconds zInterval to rate (bpm): –60,000/interval (in milliseconds) = rate (bpm) –Example: 60,000/500 ms = 120 bpm

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

7 Single-Chamber Timing

8 Single Chamber Timing Terminology zLower rate zRefractory period zBlanking period zUpper rate

9 Lower Rate Interval VP VVI / 60 zDefines the lowest rate the pacemaker will pace

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

11 Blanking Period Lower Rate Interval VP VVI / 60 zThe first portion of the refractory period zPacemaker is “blind” to any activity zDesigned to prevent oversensing pacing stimulus Blanking Period Refractory Period

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

13 Single Chamber Mode Examples

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

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

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

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

18 Other Single Chamber Operations

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

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

21 Dual-Chamber Timing

22 Benefits of Dual Chamber Pacing zProvides AV synchrony zLower incidence of atrial fibrillation zLower risk of systemic embolism and stroke zLower incidence of new congestive heart failure zLower mortality and higher survival rates

23 Benefits of Dual-Chamber Pacing StudyResults Higano et al Gallik et al Santini et al Rosenqvist et al Sulke et al Improved cardiac index during low level exercise (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, especially in patients with poor LV function Decreased incidence of mitral and tricuspid valve regurgitation

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

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

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

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

28 Dual Chamber Timing Parameters zLower rate zAV and VA intervals zUpper rate intervals zRefractory periods zBlanking periods

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

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

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

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

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

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

35 Post Ventricular Atrial Refractory Period (PVARP) Refractory Periods zVRP 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 VP Ventricular Refractory Period (VRP) A-V Interval (Atrial Refractory)

36 Blanking Periods zFirst 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)

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 Programmer The Medtronic 9790 Programmers are portable, microprocessor based instruments used to program Medtronic implantable devices 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 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 in Pacemaker Timing Parts II and III


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