1 pacemaker troubleshooting module 9. 2 objectives list steps in performing troubleshooting...

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Pacemaker TroubleshootingModule 9

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Objectives

• List steps in performing troubleshooting

• Correctly identify the following on an ECG strip:

– Pacemaker ERI behavior

– Loss of Capture

– Over- and undersensing

– Magnet behavior

– Pseudo-malfunctions

• Make clinically appropriate suggestions based on interpretation

– Identify additional information or other resources useful to diagnosing pacemaker malfunction

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Some Good Advice

• Perform all troubleshooting and all pacemaker checks the same way

– Collect the data

– Ask questions

– Keep an open mind

– Analyze, form hypothesis, test

– Don’t make assumptions

• The simplest explanation that covers all the facts, is usually the correct explanation

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The Four Solutions to Pacemaker Problems

• Re-Program – the device

• Re-Place – the system or a component

• Re-Position – the lead(s), the device

• Retreat – do nothing, because nothing is wrong

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The Process

• Observe/collect data

– Measure the ECG (e.g., A-A, V-V, A-V, V-A)

• Form your hypothesis

• Test your “solution”

• Make a suggestion

– Ask the clinician questions

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Data Sources

• Programmed parameters

• Patient symptoms

• Medical history

• Indication for implant

• Implant date

• Rhythm strip

• Device model number

• Lead model numbers

• Telemetry data

– Impedances

– Battery voltage

– Marker Channel™

• Device diagnostics

• Device RRT and EOS behaviors

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Case 1

• Information you have:

– DDD 60-130

– PAV/SAV 150-120 ms

– PVARP 310 ms

• Question: Why is rhythm irregular, sometimes fast?

– Hypotheses:

• Tracking PAF

• Oversensing (tracking a “P-wave” that is not there)

• Are these grouped beats – upper tracking rate behavior?

Click for Hint

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Case 1First Hypothesis: Tracking Paroxysmal AF

• What is the evidence for AF?

– Irregular ventricular events

– Could be “fine” AF, not visible on baseline

• What is the evidence against AF?

– Some visible P-waves

– Evidence of atrial pacing

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Case 1 Second Hypothesis: Atrial Oversensing

• What is the evidence for atrial oversensing?

– Irregular ventricular tracking

– Evidence of ventricular tracking without visible P-waves

• What is evidence against atrial oversensing?

– There may be P-waves “hidden” in some T-waves

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Case 1 Third Hypothesis: Upper Rate Behavior

• What is the evidence for Wenckebach?

– Some evidence of “grouped” beats

– Evidence of P-waves “hidden” in some T-waves

• What is evidence against Wenckebach?

– The A-A intervals don’t march out

– Evidence of atrial pacing – no need if this is UTR behavior

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Case 1What Are Your Next Steps?

• To form a better hypothesis:

– Interrogate pacemaker

– Observe ECG and Marker Channel strip

• To test the hypothesis:

– Perform sensing test – observe rhythm/markers

– Check lead impedance for low impedance (insulation break), which often causes oversensing (< about 250 Ω)

• What is the normal impedance range (assume standard leads)?

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Case 1 Final Hypothesis: Arial Oversensing

• Confirmed by

– Marker Channel annotations showing AS markers without P-waves

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Case 1 Conclusion: Arial Oversensing

• What do you consider?

– The “service” you provide to the customer is not in just interpreting pacemaker behavior

– You are there to supplement the customer’s clinical knowledge and experience with your knowledge and experience regarding the pacing system

– If the customer asks, you have to be ready to make an appropriate suggestion

• Ask questions

• Find out the relevant concerns that the customer has for this patient

• If you are uncertain, call Technical Services

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Example Case 1 Conclusion: Arial Oversensing

• Cause

– Insulation breach

– Bipolar impedance: 190 Ω

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Example Case 1 Conclusion: Artial Oversensing

• Considerations:

– How easy is it to “fix”

• Unipolar lead in situ

– What are the risks to the patient to “fix”

• Elderly, debilitated patient

– What are the risks/implications if it is not “fixed”

• Loss of AV synchrony

• Possible that AF diagnostics are not accurate

• Risk of PMT

– Are there any alternatives?

• VVI?

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Example Case 1 Conclusion: Arial Oversensing

• Cause

– Unknown

• Other resources

– Medtronic Technical Services

• 1 800 505 4636 (within the U.S.)

– Medtronic Product Performance Report

• There may be an issue with a particular Medtronic product you are not aware of

• Other manufacturers do not necessarily produce these reports

– Your colleagues

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Case 2

• Programming information:

– DDD 60–130 bpm

– PAV: 150 ms

– SAV: 120 ms

– PVARP: 310 ms

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Case 2Hypothesis

Loss of Capture

– Idioventricular rate is masquerading as a “capture/pseudo-fusion”

Click for Answer

To test hypothesis: - Perform a threshold test

Click for Answer

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Case 2Considerations

• Causes

– If there were changes in medications, or an MI, or the patient had renal failure, etc. ?

– If chronic lead impedance is high?

– If lead impedance is ok?

– If acute lead impedance is high?

• Considerations

– Program a higher output for an increased safety margin, as conditions are changing

– Suspect fracture. Could try unipolar temporarily, but this will likely require a lead replacement.

– Suspect dislodgement. Can try a higher output, but permanent fix will likely be repositioning.

– Likely a loose set screw. Need to re-open the pocket and retighten it.

Click for Answers

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Case 3

• Programming information

– DDD 60–120 bpm

– PAV: 150 ms

– SAV: 120 ms

– PVARP: 380 ms

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Case 3Hypothesis: Pacemaker Wenckebach

• Upper rate behavior

– Is this evidence of “grouped beats?”

– Do we see regular atrial activity with increasing A-V intervals?

• Intermittent atrial undersensing

– Do the pauses occur because a P-wave is not sensed, and thus, not tracked?

Click for Answer

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Case 3Hypothesis: Pacemaker Wenckebach

• How do you test this hypothesis?

– Knowing what the patient was doing when this occurred is helpful. For example, this strip was collected while the patient was on a treadmill (exercising).

– Analyze the strip:

• The regularity of the increasing A-V intervals is obvious

• The regularity of the grouped beats is suggestive

– What other hypotheses are there? For example, intermittent atrial undersensing might look like this – test for these as well.

– If possible, recreate the conditions

– Finally, what is TARP? What are the atrial intervals? Is pacemaker Wenckebach possible?

Click for Answer

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Case 3Hypothesis: Pacemaker Wenckebach

• Considerations

– Is this really a problem?

• The pacemaker is behaving normally

– What to consider if the patient’s ADL’s are compromised?

• Pacer Wenckebach occurs when the atrial rate increases and approaches the 2:1 block point

• Recall from the Timing Modules that (SAV + PVARP) = TARP, so we:

– Can increase the UTR

– And decrease TARP by:

» Less PVARP

» Less AV – use Rate Adaptive AV

» Use Auto-PVARP options

Click for Answer

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Case 4

• Your information:

– DDD 60–130 bpm

– PAV: 150 ms

– SAV: 120 ms

– PVARP: 310 ms

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Case 4Hypothesis

• What explains this atrial pace?

– Intermittent atrial undersensing. The P-wave was not “seen” and the lower rate (LRL) timed out, resulting in an atrial pace

• Review question:

– Why did this atrial pace NOT capture? (Hint: Think of the ECG module.)

• Because the atrial pacing occurred in the absolute refractory period of the atrial muscle tissue

Click for Answer

Click for Answer

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Case 4Confirming Your Hypothesis

• What would you do?

• What would you expect to see?

• Interrogate and observe the rhythm

• P-waves without markers

Click for Answers

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Case 4Testing Your Hypothesis

• What would you do to test your hypothesis?

• Perform a sensing test

– Is the device programmed correctly?

– P/R- wave amplitudes can change

• Check Lead Impedances

– Undersensing can be a symptom of a lead fracture or lead insulation failure

– Undersensing can be a symptom of lead dislodgement

Click for Answers

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Case 4Considerations

• Suppose the device were programmed to 4.0 mV atrial sensitivity, and the P-waves measure 4.0- 5.0 mV. Would programming a sensing value of 2.0 mV make it more or less sensitive?

• Would you choose 2.0 mV or a value even more sensitive if the device operations remained normal? Why?

• 2.0 mV is more sensitive than 4.0 mV

• Program to a more sensitive value to make sure the device can sense AF, for example

Click for Answers

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One Consequence of Atrial Undersensing

• Programming information:

– DDD 60–120 bpm

– PAC: 150 ms

– SAV: 120 ms

– PVARP: 310 ms

• PMT (pacemaker mediated tachycardia) caused by atrial undersensing and retrograde conduction

• The abrupt onset is one hallmark of PMT

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PMTPacemaker Mediated Tachycardia

• Occurrence minimized with introduction of Auto-PVARP or dynamic TARP operations

– Which provide longer pacemaker atrial refractory periods at lower rates

• PMT is similar to a re-entrant tachycardia discussed in Module 1

– Except the pacemaker forms part of the re-entrant circuit

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PMT Mechanism

• A ventricular event occurs

– Paced or sensed – we show a PVC here

• Conducts retrograde through the AV node (typically)

• And results in an atrial sense

– Which starts an SAV, and results in a ventricular pace

• This is again conducted retrograde, and the sequence starts again

– VP, which goes retrograde V-A, resulting in an AS starting an SAV, resulting in a…VP which goes retrograde V-A resulting in an AS starting an SAV resulting in a… VP which goes retrograde V-A resulting in an AS starting an SAV resulting in a… VP which goes retrograde V-A resulting in an AS starting an SAV resulting in a…

– You get the idea

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PMT Requirements

• For the sequence to be maintained:

– The AV node and atrium must be able to conduct retrograde, i.e., not be depolarized

– The pacemaker must be able to sense this retrograde depolarization, i.e., not be in a refractory period

– This timing ‘ballet’ must persist

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Case 5Hypotheses

• Is this PMT?

• Is this simply the pacemaker tracking a sinus tachycardia?

– DDD 60-120 PAC/SAV 150-120 ms, PVARP 310 ms

• What was the patient doing when this occurred?

• If exercising, it may favor tracking

• If at rest, be suspicious of PMT

Click for Answers

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Case 5Confirming Your Hypotheses

• Place a magnet on the device during the tachycardia. What happens?

• If this is PMT, what would you expect to see?

• If this is tracking, what would you expect to see?

• A magnet makes the pacemaker DOO

• PMT requires atrial sensing

– DOO suspends the pacemaker’s sensing function, so the PMT breaks

• Evidence of atrial tachycardia during asynchronous operation

Click for Answers

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Case 5Confirming Your Hypotheses

• Place a magnet on the device

• DOO suspends sensing and the tachycardia terminates

• No evidence of atrial tachycardia during the asynchronous operation

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Case 5Considerations

• The AV node and atrium must be able to conduct retrograde (i.e., not be depolarized)

• The pacemaker must be able to sense this retrograde depolarization (i.e., atrial event falling outside of a refractory period)

• Typical causes

– Loss of atrial capture

– Loss of atrial sensing (atrial undersensing)

– Atrial oversensing

– PVC with retrograde conduction/accessory pathway

• Typical causes

– PVARP too short

– Auto-PVARP not in use

– PVC Response not in use

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Addressing PMT

• Test

– Atrial output threshold

– Atrial sensing test

– Retrograde conduction

• To fix

– Reprogram the pacemaker outputs as needed

– Increase PVARP to make the retrograde atrial event an AR

• Turn PMT Intervention “On”

• Turn PVC Response “On”

– Rarely, may need to reposition a lead or ablate a pathway

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Solution: PVC Response

• Designed to prevent sensing of retrograde P-waves, when they happen due to a PVC

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Solution: PMT Intervention

• Designed to interrupt a Pacemaker-Mediated Tachycardia

DDD / 60 / 120

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Case 6

• Programming information

– DDD 60–130 bpm

– PAV: 150 ms

– SAV: 120 ms

– PVARP: 320 ms

• Any hypotheses?

– Atrial undersensing

– Ventricular oversensing

Click for Hint

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Case 6Hypothesis: Atrial Undersensing

• If this P-wave is not sensed, and not tracked, then determine when the next atrial event should occur in the timing sequence

• DDD 60 (1000 ms) minus the SAV (120 ms) = 880 ms from the last QRS to the next atrial pace (the V-A interval). We should see an atrial pace at the X.

• Thus, this cannot be atrial undersensing

X

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Case 6Hypothesis: Ventricular Oversensing

• Remember the information

– A-A = 1000 ms

– A-V = 120 ms

– PVARP 320 ms

– Calculated the V-A = 880 ms

VS

AR

Measure the V-A interval from the atrial pace, and assume the pacemaker sensed a ventricular “event” here.

The atrial event then fell in the PVARP of this “event” – and can not be used for timing, thus it did not start an SAV.

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• What would you do?

• What would you expect to see?

• Interrogate and observe the rhythm

• VS/VR markers without QRS complexes

Click for Answers

Case 6Confirming the Hypothesis: Ventricular Oversensing

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Case 6Confirming the Hypothesis: Ventricular Oversensing

• But suppose you interrogate and consistently get this strip. What next?

– Run a sensing test anyway

– Try to provoke oversensing

– Program to non-RR mode

• Arm/shoulder movement

• Have patient reach across his/her body

• Observe Marker Channel for VS without a QRS

– More common with unipolar sensing

Click for Answers

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Review Questions

• What patient complaints might you suspect with this strip?

• What pacemaker telemetry data might indicate the cause?

• What long-term effect will this condition have on device diagnostics?

• C/O syncope, presyncope, vertigo, weakness…

• Ventricular lead impedance

• Ventricular rate diagnostics inaccurate because of this oversensing – may be interpreted as arrhythmia

Click for Answers

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A Little Advice…

• When you see evidence of “over pacing” i.e., pacing despite intrinsic activity

– Consider undersensing

– See Case 4

• When you see evidence of “under-pacing” i.e., pauses without pacing

– Consider oversensing

– See Case 6

• These rules are NOT absolute

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Case 7No Programmer Available

Questions to ask yourself:

• Is this a single chamber VVI pacemaker?

• If it is dual chamber, is it tracking?

– But if it is tracking what would cause AV intervals to change?

• If it is not tracking, e.g., because of atrial undersensing, what causes the V pacing?

• Can’t be VVI, see A-V pacing. Must be dual-chamber device

• Hard to believe this is tracking with these AV intervals, and it can’t be Wenckebach at this rate

• Good question!

Click for HintsClick for Answers

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Case 7No Programmer Available

Questions to ask yourself:

• What kind of pacemaker:

– Paces in the atrium and ventricle

– Senses in the atrium and ventricle

– But does NOT track?

• The simplest answer that explains all the facts, is likely the correct answer.

• How about DDI(R)

– The response to sensing is to inhibit

– No SAV can be initiated

– Without an AP, the ventricle is paced at the lower rate

– If after a V-A interval, there is no AS, then an AP and a PAV

Click for Hints

Click for Answers

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Case 7Review Questions

• What is the underlying rhythm?

• Is the pacing mode appropriate for this rhythm?

• What would be a better choice?

• Why?

• It appears to be Complete Heart Block

– No evidence of AV synchrony

• DDIR? No

• DDD or even VDD

• It looks like the atrium is reliable

Click for Answers

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Case 8No Programmer Available

• Patient is in the hospital on bed rest

• Admitted for non-cardiac problem

– Medical record indicates he has a dual chamber pacemaker

A physician hands you this and says, ”I think he is having PMT, what is your opinion?”

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Case 8No Programmer Available: Hypotheses

• Is this PMT?

• If not PMT, what would cause atrial pacing at this rate (which is…?)

• How can it be Rate Response – he is at rest?

• No, PMT requires tracking – this shows atrial pacing

• Atrial rate of about 100 bpm

– Could be Rate Reponse pacing

– Or a special pacemaker intervention

• Rate Response could be programmed too aggressively. It might be an MV sensor, and he is having a fever or an anxiety attack…

Click for Answers

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Case 8No Programmer Available: Confirming the Hypothesis

• What resources are available to you?

– Medical Record and Nurse

– Office pacemaker chart

– Technical Services

– Patient

• What information would you look for?

– Mode of pacemaker

• Patient vital signs/activity

– Model

– Last programmed values

– Indication

– Interpretation/Confirmation of the ECG strip

• Other explanations

– What were you doing?

Click for Answers

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Case 9

• Programming information

– DDDR 60-130 bpm

– PAV: 150 ms

– SAV 120 ms

– PVARP: Auto

– No other therapies or unusual programming options chosen

• How can there be pacing and sensing at less than the lower rate?

• Is this pacemaker malfunctioning?

Atrial Rate Histogram

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Case 9Hypotheses

• Phenomena:

– The device pace appears to be operating at less than the lower rate

• Hypotheses:

– There are special programming options that could affect the histogram producing these results

• Hysteresis

• Sleep Function

– The device is actually programmed to a lower rate of 40 bpm

– The programming information is correct, so the device is malfunctioning

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Case 9Why is the Pacemaker Altering the Lower Rate?

• Interrogation confirms:

– Programming information is correct

– DDDR 60-130 bpm, PAV/SAV 150/120 ms, PVARP-Auto

– Hysteresis and Sleep Function: Off

Click for Hint

Recall from Module 7:Normally, pacemakers use A-A timing to maintain a steady atrial rate. V-V timing is used only under some special circumstances. This is an example of the effect the change in fundamental timing has on the pacemaker.

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Case 9

• Basic IPG timing is A-A, but after a (pacemaker-defined) PVC, it switches to V-V timing

• This maintains a stable V-V interval (at the lower or sensor indicated rate, whichever is faster and depending on the mode)

• The resulting AS-AP interval may exceed LRL and is noted in the histogram

DDDR 60/1301600ms

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Case 9Considerations

• Is the pacemaker malfunctioning?

• Is the patient symptomatic with this pacemaker operation?

• What do you suggest?

• No, this is normal pacemaker behavior

• Unlikely, as the ventricular rate is relatively stable

• The pacemaker is implanted in order to address patient symptoms. Concentrate on the patient, not on the diagnostic.Click for Answers

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RecapThe Four Solutions to Pacemaker Problems

• Re-Program – the device

• Re-Place – the system or a component

• Re-Position – the lead(s), the device

• Retreat – do nothing, because nothing is wrong

So….

• Observe/Collect data

• Measure (e.g., A-A, V-V, A-V, V-A)

• Form your hypothesis

• Test your “solution”

• Make a suggestion

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Final Nugget

• Most pacemaker “malfunctions” can be explained by:

– Dislodged leads or failing leads

– Battery end-of-life

– Inappropriate programming due to

• Changing patient conditions

• An error

– Normal operations you do not fully understand

• Sudden changes in timing are almost always normal pacemaker (if advanced) operations

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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.

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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.

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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.

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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.

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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.

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.