Presentation on theme: "Advanced Pacemaker Operations Module 7"— Presentation transcript:
1 Advanced Pacemaker Operations Module 7 Student NotesIt is possible that you may require additional supplemental materials to enhance your knowledge or provide more practice. If you feel this is necessary for you, ask your instructor for suggestions on books or other tools.Instructor NotesThis module should take approximately 2 hours to cover.To deliver this module, the following materials are recommended:Printed participant guides for each participantOverhead projector and screenOptional: Whiteboard or flip chartWhile delivering the module engage, the learners by asking questions and getting them to talk based on their previous subject knowledge.Evaluate the learners by delivering the knowledge check at the end of this module. An acceptable score is 80%.World HeadquartersMedtronic, Inc.710 Medtronic ParkwayMinneapolis, MNUSAInternet:Tel: (763)EuropeMedtronic International Trading SàrlRoute du MolliauCh TolochenazSwitzerlandTel: (41 21)Asia-PacificMedtronic International, Ltd.16/F Manulife PlazaThe Lee Gardens, 33 Hysan AvenueCauseway BayHong KongTel: (852)CanadaMedtronic of Canada Ltd.6733 Kitimat RoadMississauga, Ontario L5N 1W3Tel: (905)Toll-free: 1 (800)Medtronic USA, Inc.Toll-free: 1 (800)(24-hour technical support for physicians and medical professionals)Latin AmericaMedtronic USA, Inc.Doral Corporate Center II3750 NW 87th Avenue Suite 700Miami, FL 33178USATel: (305)UC d ENMedtronic, Inc.Minneapolis, MNJanuary 2008
2 Objectives Define: Blanking and refractory Complete VVI and DDD timing diagramsCorrectly identifying PVARP, PVAB, PPAB, and TARPIdentify events in refractory and blanking, and their effect on timingCorrectly identify Marker Channel™ notationsIdentify upper rate behaviorsCalculate 2:1 vs. Wenckebach ratesStudent NotesInstructor Notes
3 Marker Channel™Very useful in helping you understand how the IPG is interpreting eventsEach manufacturer has its own codeMedtronic’s code:AS Atrial SenseAP Atrial PaceAR Atrial RefractoryVS Ventricular SenseVP Ventricular PaceVR Ventricular RefractoryStudent NotesA note on Marker Channel diagnostics. These were first introduced by Medtronic and greatly simplify the interpretation of pacemaker behavior – as you will see when we come to the troubleshooting module!The Marker Channel notations are available once the pacemaker is interrogated, and they are displayed on both the Programmer ECG screen and print outs. Caution – each pacemaker manufacturer has its own codes for events. Medtronic’s are displayed on this slide.Note: The Marker Channel is the devices interpretation of events. If sensing is appropriate, the following Marker Channels correspond to the listed physiologic event:AS = P-waveVS = R-waveInstructor NotesThere are other Medtronic Marker Channel notations that we’ll cover later.
4 What Do You Think Would Happen Next If… The QRS was sensed by the atrial channel?ASAPVPNote: The Marker Channel tells you how the pacemaker is interpreting these events.DDD 60Click for AnswerStudent NotesInstructor NotesAsk: Suppose we had a dual chamber pacemaker, and it suddenly started sensing a QRS on the atrial channel. What effect might this have on pacemaker behavior? Would the pacemaker operate as planned?The QRS is sensed on the atrial channel, and it is interpreted by the pacemaker as a P-wave. We call the phenomena Far-field R-wave sensing (FFRW), and the effect might inhibit the pacemaker and restart the underlying lower-rate timer. It will also trigger an AV delay, and ventricular pacing will occur faster than desired. Thus, the pacemaker would not be operating as intended.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.
5 What Do You Think Would Happen Next If… These T-waves were sensed by the ventricular channel?Actual Rate: 50 bpm or 1200 msVPVSVPVSProgrammed: VVI 60Student NotesThe next ventricular pace would be inhibited because the pacemaker thinks the T-wave is an R-wave.Obviously, this also is not how we want a pacemaker to behave.Instructor NotesHere is another, and perhaps more common example of a pacemaker problem – T-wave oversensing.Ask: In this VVI pacemaker, what happens if a T-wave is sensed by the ventricular channel?It is interpreted as a QRS and the pacemaker inhibits and restartsAsk: Is this how we want it to behave?No, it is not desirableClick for Answer
6 Blanking and Refractory Periods Blanking PeriodA period of time during which the sense amplifiers are off, and the pacemaker is “blind”Some blanking periods are programmable, some are non-programmableRefractory PeriodA period of time during which sensed events are ignored for timing purposes, but included in diagnostic countersSome refractory periods are programmable, some non-programmableStudent NotesBlanking and Refractory periods were introduced as a way to help manage what the pacemaker is sensing, and when it uses the information.Blanking periods are somewhat analogous to the Absolute Refractory Period we studied in an earlier module. In the case of a pacemaker, during Blanking it is unable to SENSE. The sense amplifier is OFF.During Refractory the pacemaker is able to sense, but it ignores the event for the purposes of timing. For example, a refractory event may be noted in a diagnostic counter, but it will not alter or effect timing.Instructor Notes
7 Why Do We Use Refractory and Blanking Periods? Pacemaker sensing occurs when a signal is large enough to cross the sensing thresholdSensing does not tells us anything about the origin or morphology of the sensed event, only its “size.”5.0 mV2.5 mV1.25 mVStudent NotesAs we discussed earlier, a pacemaker only notes an event when it crosses the programmable sensing threshold, but when that occurs, the pacemaker is still unable to determine anything more about that signal. Nothing about its morphology, its origin, is looked at. Nothing but that it exceeded the sensing threshold.Instructor NotesThe second waveform on this slide is a T-wave.Ask: Why do we need these periods in pacemakers?Since nothing about the waveforms morphology or its origin is know by the pacemaker, timing must be utilized to classify the event as something other than an R-wave1.25 mV SensitivityTime
8 Why Do We Use Refractory and Blanking Periods? By manipulating the sense amplifiers, we filter signals based on their relationship5.0 mVThe potential for digitizing these signals may someday allow pacemakers to discriminate signals based on morphology rather than just on their relationship.2.5 mVSENSE!1.25 mVStudent NotesHowever, by applying blanking and refractory periods, it allows us to make some discrimination about the signal based on its relationships with other signals around it.In the example above, immediately upon sensing the signal, the amplifier goes into blanking – it goes “dark” for a programmable period of time. Then the amplifier restarts, but it is in refractory – the pacemaker ignores signals for a programmable period of time. In other words, during the refractory period, the pacemaker sees the signal, but it does not affect pacemaker timing.Instructor NotesSensingBlankingRefractoryTime
9 Let’s Look at the VVI Example Again… Now, is the T-wave sensed by the ventricular channel?VPVRVVI 60Click for AnswerStudent NotesInstructor NotesFor review:Ask: What do the following markers represent?VS—ventricular senseVP—ventricular paceVR—ventricular refractoryAsk: This is the same ECG previously seen. What is the new effect on this VVI ECG?The T-waves fall in a refractory period and ignored for timeing purposesThe T-wave falls in the ventricular refractory period (VR), and it is ignored for timing purposes.The VVI pacemaker is operating normally.
10 VVI Timing Note the addition of the Blanking and Refractory periods VPVR1000 msBlankingRefractoryVRP 320 msStudent NotesBlanking and refractory periods occur in every timing cycle, and in both dual and single chamber pacemakers.The purpose of the ventricular blanking period is to avoid sensing the ventricular pace.The purpose of the ventricular refractory period is to avoid sensing T-waves.Instructor NotesThe pacemaker applies these periods to every timing cycle.
11 T-wave SensingIs there another way to program the pacemaker to ignore the T-waves?Click for AnswerVPVR1000 msVRP 320 msBlankingRefractoryStudent NotesInstructor NotesWe 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.
12 Dual Chamber Timing Refractory and Blanking Periods ARPPVARPVRPPVABThose affecting the atrial channel are indicated above the ECG baseline.Those affecting the ventricular channel are indicated below the ECG baseline.Student NotesWhen drawing out timing diagrams, usually periods and notations referring to the atrial channel are drawn above the ECG baseline. Those referring to the ventricle are below the line.Instructor NotesRed: BlankingOrange: Refractory period
13 Dual Chamber Timing Atrial Refractory and Blanking Periods Post Ventricular Atrial BlankingAtrial Refractory and Blanking PeriodsPVABAtrial BlankingARPPVARPVRPStudent NotesThe atrial blanking and refractory periods are shown for DDD timing. The following is information on the purpose of each period:Atrial Blanking—prevents the pacemaker from being “self-inhibited” by the atrial pacing outputAtrial Refractory Period—ignores sensed events on the atrial channel during the AV delay, so they do not restart the AV intervalPost Ventricular Atrial Blanking—prevents Far-field R-wave sensing of the ventricular pacing output, and the R-wave, on the atrial channelPost Ventricular Atrial Refractory Period—prevents the AV interval from restarting due to sensed events (Far-field R-waves or retrograde conduction)Keep in mind that the periods time out simultaneously. Look at PVARP and PVAB. They both begin with a ventricular pace (or sensed QRS). The PVAB is programmed to expire before PVARP does.The atrial blanking that is shown, occurs only if there is an atrial pacing output. Had a P-wave occurred (an atrial sense), the AV delay would have been an atrial refractory period only.Instructor NotesPost Ventricular Atrial Refractory PeriodAtrial Refractory Period
14 Post Atrial Ventricular Blanking Ventricular Refractory Period Dual Chamber TimingVentricular Refractory and Blanking PeriodsPVABARPPVARPPost Atrial Ventricular BlankingVRPVentricular Refractory PeriodStudent NotesThe ventricular blanking and refractory periods are shown here in typical DDD timing. The following is information on the purpose of each period:Post Atrial Ventricular Blanking—prevents the ventricle from sensing the atrial pacing outputVentricular Blanking—prevents “self-inhibition” from the ventricular pacing outputVentricular Refractory Period—prevents oversensing of T-wavesThe PAVB occurs only with an atrial pace.Instructor NotesVentricular Blanking
15 Dual Chamber Timing Atrial Pace (AP) - Ventricular Pace (VP) example A-A intervalVRPARPPVARPPVABPAVV-A intervalDDD 60Student NotesHere we show the timing for A-V sequential pacing in the DDD mode. We’ve added the lower rate intervals and AV delays. These apply to every pacemaker cycle.Instructor NotesThe pacemaker applies these periods every timing cycle.
16 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 intervalNormally, the device is designed to always use A-A timing – to maintain a steady atrial rateA-A intervalPAVV-A intervalStudent NotesThe lower rate interval (escape, or A-A interval) determines the devices minimum rate.Thus, a Lower Rate of 60 bpm is an escape (or an A-A) interval of 1000 ms. Unless otherwise inhibited, the pacemaker will deliver an atrial pace every second, and in DDD, this atrial pace will start a PAV.Instructor NotesVRPARPPVARPPVAB
17 Dual Chamber Timing Upper Tracking Rate (UTR) The maximum rate the ventricles will be paced 1:1 in response to atrial sensed eventsVRPARPPVARPPVABA-A intervalSAVV-A intervalUTRStudent NotesThe upper tracking rate (UTR) determines the maximum rate the pacemaker will continue to time out the programmed SAV. In other words, with a UTR of 120 bpm, the pacemaker will track the atrium (i.e., provide a ventricular pace for every P-wave) as long as the A-A interval is longer than 500 ms.Why 500 ms? Because 500 ms = 120 bpm.Instructor Notes
18 1:1 tracking of any atrial sense Dual Chamber TimingTracking1:1 tracking (atrial sense – ventricular pace) occurs at rates above the Lower Rate, but below the Upper Tracking Rate1:1 tracking of any atrial senseA-A intervalA-A intervalUTRVRPARPPVARPPVABStudent NotesSo let’s assume DDD (lower rate – UTR). The pacemaker is tracking 1:1 (providing a VP for every AS) as long as:The A-A is < 1000 ms, andThe A-A is > 500 msInstructor NotesThe dotted lines on this slide indicate the interval in which 1:1 tracking can occur.
19 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 shorterA-A intervalVRPARPPVARPPVABUTRA-A intervalV-A intervalSAVV-A intervalSAVUTRVRPARPPVARPPVABStudent NotesThe reason the pacemaker responds this way is because each pacemaker cycle is evaluated in relation to the one previous. The pacemaker is measuring the A-A interval. If it is less than 500 ms (with a UTR of 120 bpm), it then must respond differently by delaying the ventricular pace.Instructor NotesThe pacemaker’s response to high atrial rates is called upper rate behavior. This is covered in the “Dual Chamber Timing: Upper Rate Behavior” section of this module.In other words, the next atrial sense is getting closer to the previous ventricular event.
20 Dual Chamber Timing Upper Rate Behavior Student NotesInstructor NotesThis section discusses pacemaker Wenckebach and 2:1 block.These two upper rate behaviors interact with each other, but it is important to understand them individually first. Therefore, this section introduces them as separate concepts.
21 Upper Rate Behavior Pacemaker Wenckebach Caused by the atrial rate exceeding the Upper Tracking RateStudent NotesPacemaker Wenckebach has the characteristics of Wenckebach—the pattern of the PR (AV) interval gradually extending, beat-to-beat, until an atrial event falls into the PVARP and cannot restart an AV interval. In effect, a ventricular beat is “dropped.”Instructor NotesUse the Marker Channel to point out the atrial rate, since the P-waves on the surface ECG are difficult to see.
22 Upper Rate Behavior Pacemaker Wenckebach Prolongs the SAV until upper rate limit expiresProduces gradual change in tracking rate ratioA-A intervalA-A intervalA-A intervalUTRUTRUTRASASARAPStudent NotesPacemaker Wenckebach mechansim:The atrial rate increased to above the Upper Tracking RateThe SAV times out, but a ventricular pace at that time would violate the UTRThe effective AV delay is prolonged until the end of the UTRThe delayed ventriclar pace delays the start of PVARPEventually, the next P-wave falls into the refractory periodVentricular tracking is lost for one beatInstructor NotesARPPVARPARPPVARPARPPVARPSAVSAVPAVVPVPVP
23 Wenckebach Example Pacemaker patient on an exercise test 4:3 Wenckebach operationEach AS (P-wave) is followed by an increasing SAV, and then the VPEventually an atrial beat is not tracked, and a ventricular beat is droppedStudent NotesOn this slide we have an example of pacemaker Wenckebach obtained while a patient is having a graded exercise (stress) test. Note the increasing AV intervals and the 4 AS:3 VP (4:3) pattern.Instructor NotesAsk: Why is the atrial beat not tracked?The P-wave fell into the PVARP of the previous ventricular eventThe next slide illustrates this answer.
24 Wenckebach ExampleThis 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.Student NotesHere we took the ECG and are zooming in.By changing the beat-to-beat relationship and the relative relationship of the previous cycle’s PVARP to the next AS, eventually an AS falls in a PVARP – it is an AR.Instructor NotesAsk: What does this mean to pacemaker timing?A refractory event is ignored for purposes of timing, so the pacemaker will not use it to start an SAV. Without an AV interval, there can be no VP. Thus, a beat is “dropped.”
25 Upper Rate Behavior 2:1 Block Occurs when P-waves are faster than TARP TARP = SAV + PVARPARPPVARPARPPVARPARPTARPTARPTARPASARASARASSAVSAVSAVStudent NotesThe total time that the atrial chamber of the pacemaker is in refractory, is during the AV interval and the PVARP. The Total Atrial Refractory Period (TARP) is equal to the SAV interval plus the PVARP. The TARP is important to understand as it defines the highest rate that the pacemaker will track atrial events before 2:1 block occurs.Instructor NotesTARP is an interval, so it must be converted to beats per minute in order to compare it to an atrial rate.Ask: Given an SAV of 200 ms, and a PVARP of 300 ms, what is TARP?TARP = 500 msAsk: Given the same parameters, what pacemaker rhythm will result from an atrial rate of 130 bpm?2:1 blockExplanation:TARP of 500 ms converts to 120 bpm (60,000 / 500 ms = 120 bpm)The atrial rate (130 bpm) is faster than TARP, resulting in 2:1 blockVPVPVP
26 Upper Rate Behavior 2:1 Block Caused by the atrial rate exceeding the Total Atrial Refractory Period (TARP)Student NotesPacemaker 2:1 block is characterized by two sensed P-waves per paced QRS complex. This pattern develops because every other P-wave falls into PVARP.Instructor Notes
27 Knowledge CheckGiven the following pacemaker parameters, what rhythm will result from an atrial rate of 130 bpm?UTR = 120 bpmSAV = 150 msPVARP = 250 msPacemaker WenckebachGiven the same pacemaker parameters, what atrial rate would result in 2:1 block?An atrial rate above 150 bpmClick for AnswerClick for AnswerStudent NotesInstructor NotesUse this knowledge check to make sure that the learners understand Wenckeback and 2:1 block as independent concepts. It is important to understand them independently because the next several slides show how the two concepts interact with one another.
28 Upper Rate Behavior UTR 1:1 Atrial Tracking Wenckebach 2:1 Block Ventricular RateLRNoVentricularPacingStudent NotesWhen the intrinsic atrial rate approaches (and exceeds) the programmed upper rate (assuming the TARP is less than the upper rate interval), pacemaker operations will change from 1:1 tracking operations, to blocking operations, which are designed to prevent tracking atrial arrhythmias, which are too fast, and will likely cause patients to become symptomatic. The jagged line represents Wenckebach operation, characterized by a lengthening of the A-V interval, which occurs as the atrial rate exceeds the upper rate limit. If the atrial rate continues to increase, 2:1 block will occur, which means that every other P-wave will fall into refractory and will not be sensed. The ventricular paced rate will typically be half the atrial rate.Instructor NotesThis slide illustrates the relationship between pacemaker Wenckeback and 2:1 block.This slide builds from left to right, indicating a rise in atrial rate. As the atrial rate increases, illustrate to the learners the three responses to an increase in atrial rate:1:1 atrial trackingWenckeback2:1 blockLRUTRTARPAtrial Rate= Ventricular Pacing
29 Upper Rate Behavior UTR Ventricular Rate LR 1:1 Atrial Tracking NoVentricularPacing1:1 AtrialTrackingWenckebach2:1 BlockStudent NotesIf the upper tracking rate interval is longer than the TARP, the pacemaker will exhibit Wenckebach behavior for some period of time before it goes into a 2:1 block pattern as the atrial rate increases.If the upper rate interval is shorter than the TARP, the pacemaker will exhibit 2:1 block behavior first and will never be able to achieve the upper tracking rate as the atrial rate increases.Instructor NotesThis slide illustrates the relationship between pacemaker Wenckeback and 2:1 block.When animated, this slide shows what happens when TARP is too long:Lower atrial rates create a 2:1 blockEssentially eliminating the Wenckebach window at the UTRAsk: Is achieving 2:1 block immediately at the UTR a desirable situation?No, this situation is not as desirable as the situation in which there is a period of Wenckebach before 2:1 block. Patients can tolerate the gradual ventricular rate drop of Wenckebach better than the precipitous ventricular rate drop caused by 2:1 block.LRUTRTARP= Ventricular PacingAtrial Rate
30 Achieving a Higher UTR without Block Decrease SAVDecrease PVARPPVARPARPSAVASRTARPPVARPARPSAVASRTARPPVARPARPSAVASTARPIncreased TrackingSAVASPVARPARPTARPIncreased TrackingStudent NotesThere are 2 choices available to avoid 2:1 block at too slow of an atrial rate:Decrease the AV interval. However, this may result in more ventricular pacing, which may have consequences for the patient. Rate-Adaptive AV will do this automatically for us.Decrease PVARP. Typically this is the choice we might be inclined to make.In both cases, the effect is to increase the 1:1 tracking window and to allow for Wenckebach at the UTR.Instructor NotesThis slide builds on mouse clicks to show how TARP is decreased by decreasing SAV and then PVARP. In each instance, this slide shows how doing so improves tracking.SAVASSAVAS
31 Achieving a Higher UTR without Block SAV and PVARP managed automaticallyProgramming Rate-Adaptive AV to “On”This will automatically decrease the SAV/PAV as the atrial rate increasesProgramming PVARP to “Auto”This will automatically decrease the PVARP as the atrial rate increasesStudent NotesAs we mentioned earlier, TARP is the Total Atrial Refractory Period. When we manipulate either, or both, the AV or PVARP, we are manipulating TARP.Rate-Adaptive AV (RAAV) is one way to allow the pacemaker to decrease the AV delay automatically, in response to faster atrial rates.Automatic PVARP, or Auto PVARP, alters PVARP in response to increasing atrial rates. This permits long PVARP at slow rates to protect against the effects of retrograde conduction, but also permits a shorter TARP at faster atrial rates, so high UTR can be achieved without worrying about 2:1 block.Instructor Notes
32 If Long TARP is the Problem… Why not just program short AV Intervals or short PVARP?Short AV intervals may force ventricular pacingShort PVARP may allow retrograde conduction to be sensedConsider 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).Student NotesPMT is covered in more detail in “CorePace Module 8: Troubleshooting.”Instructor Notes
33 Status Check Can you identify the following Marker Channel notations? Click for AnswerASVRARAPVPVSAn Atrial Sense (P-wave)Ventricular RefractoryAtrial RefractoryAtrial PaceVentricular PaceA Ventricular Sense (QRS or R-wave)Student NotesInstructor Notes
34 Status Check Can you complete this timing diagram? Click for Answer VP VRPVPV. BlankingLower Rate IntervalStudent NotesInstructor Notes
35 Status Check Complete this timing diagram Show: Atrial Refractory during the AV IntervalPVARP with PVABVRPAtrial Refractory during the AV IntervalPVARP with PVABVRPStudent NotesInstructor NotesClick for Answer
36 Status Check You are called to evaluate this rhythm strip Obtained while the patient is having an exercise testClinician thinks it is loss of capturePatient’s underlying rhythm is CHBWhat is going on?Student NotesInstructor NotesAsk: What is going on?Pacemaker 2:1 block2:1 block. P-wavesClick for Answer
37 Status Check What mode do you think this is? Calculate the Atrial and Ventricular ratesPropose a programming solution to resolve this430 ms860 msStudent NotesInstructor NotesAsk: What mode do you think this is?DDDAsk: What are the atrial and ventricular rates?Atrial rate: 430 ms or 140 bpmVentricular rate: 860 ms or 70 bpmAsk: What are some programming solutions?Increase UTR to above 140 bpm, if not already, and if it is appropriate for the patientTurn on Rate Adapted AVTurn on Auto PVARPDDD 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.Click for Answer
38 Status CheckGiven the following parameters, what will occur first as the patient’s atrial rate increases? Wenckebach or 2:1 block?Upper Tracking Rate: 120 bpmSAV = 200 msPVARP = 350 ms2:1 block will occur firstClick for AnswerStudent NotesInstructor NotesAsk: 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 ms2:1 block will occur firstExplanation:TARP = SAV + PVARPTARP = 200 ms msTARP = 550 ms550 ms corresponds to a rate of 109 bpmSince 2:1 block occurs at a slower rate than the programmed UTR (109 bpm < 120 bpm), 2:1 block will occur first
39 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.ContraindicationsIPGs 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.
40 Brief Statements (continued) Warnings/PrecautionsChanges 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 complicationsPotential 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 and/or consult Medtronic’s website atCaution: Federal law (USA) restricts these devices to sale by or on the order of a physician.
41 Brief Statement: Medtronic Leads IndicationsMedtronic 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 indicatedContraindicationsMedtronic 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.
42 Brief Statement: Medtronic Leads (continued) Warnings/PrecautionsPeople 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 ComplicationsPotential 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 and/or consult Medtronic’s website atCaution: Federal law (USA) restricts this device to sale by or on the order of a physician.
43 DisclosureNOTE: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.
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