TroubleshootingTroubleshootingPart IPart I

Objectives:Objectives:

Understand the four basic steps used to solve troubleshooting problems

Identify ECG abnormalities that result from pacing system malfunction and pseudomalfunction

Recognize data and resources available to aid in troubleshooting pacing system anomalies

Discern pacemaker functions that can affect patient hemodynamics

Describe the causes of pacemaker system anomalies and propose a potential solution

The Steps Used in Troubleshooting Are Simple and The Steps Used in Troubleshooting Are Simple and Remain the Same for Each Type of ProblemRemain the Same for Each Type of Problem

Define the problem

Identify the cause of the problem

Correct the problem

Verify the solution

Defining the Problem and Defining the Problem and Identifying the CauseIdentifying the Cause

Potential Problems Identifiable on an ECG Can Potential Problems Identifiable on an ECG Can Generally Be Assigned to Five Categories:Generally Be Assigned to Five Categories:

Undersensing

Oversensing

Noncapture

No output

Pseudomalfunction

UndersensingUndersensing

An intrinsic depolarization that is present, yet not seen or sensed by the pacemaker

P-wavenot sensed

Atrial UndersensingAtrial Undersensing

Undersensing May Be Caused By:Undersensing May Be Caused By:

Inappropriately programmed sensitivity

Lead dislodgment

Lead failure:

– Insulation break; conductor fracture

Lead maturation

Change in the native signal

OversensingOversensing

Ventricular OversensingVentricular Oversensing

Marker channel shows intrinsic activity...

...Though no activity is present

The sensing of an inappropriate signal

– Can be physiologic or nonphysiologic

Oversensing May Be Caused By:Oversensing May Be Caused By:

Lead failure

Poor connection at connector block

Exposure to interference

Noncapture is Exhibited By:Noncapture is Exhibited By:

No evidence of depolarization after pacing artifact

Loss of capture

Noncapture May Be Caused By:Noncapture May Be Caused By:

Lead dislodgment

Low output

Lead maturation

Poor connection at connector block

Lead failure

Less Common Causes of Less Common Causes of Noncapture May Include:Noncapture May Include:

Twiddler’s syndrome

Electrolyte abnormalities – e.g., hyperkalemia

Myocardial infarction

Drug therapy

Battery depletion

Exit block

No OutputNo Output

Pacemaker artifacts do not appear on the ECG; rate is less than the lower rate

Pacing output delivered; no evidence of pacing spike is seen

No Output May Be Caused By:No Output May Be Caused By:

Poor connection at connector block

Lead failure

Battery depletion

Circuit failure

PseudomalfunctionsPseudomalfunctions

Pseudomalfunctions are defined as:

Unusual

Unexpected

Eccentric

ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function

Pseudomalfunctions May Be Classified Pseudomalfunctions May Be Classified Under the Following Categories:Under the Following Categories:

Rate

AV interval/refractory periods

Mode

Rate Changes May Occur Due to Rate Changes May Occur Due to Normal Device Operation:Normal Device Operation:

Magnet operation

Timing variations

– A-A versus V-V timing

Upper rate behavior

– Pseudo-Wenckebach; 2:1 block

Electrical reset

Battery depletion

PMT intervention

Rate response

Magnet OperationMagnet Operation

Magnet application causes asynchronous pacing at a designated “magnet” rate

A to A vs. V to V TimingA to A vs. V to V Timing

V-A = 800 AV = 200 AV = 150 V-A = 850

A to A = 1000 ms A to A = 1000 ms

V-A = 800 AV = 200 AV = 150 V-A = 800

A to A = 1000 ms A to A = 950 ms

Atrial rate is held constant at 60 ppm

Atrial rate varies with intrinsic ventricular conduction

A-A Timing

V-V Timing

Upper Rate BehaviorUpper Rate Behavior

Pseudo-Wenckebach operation will cause a fluctuation in rate

Upper Rate BehaviorUpper Rate Behavior

2:1 block operation will cause a drastic drop in rate

Electrical Reset and Battery DepletionElectrical Reset and Battery Depletion

Reset may occur due to exposure to electromagnetic interference (EMI) – e.g., electrocautery, defibrillation, causing reversion to a “back-up” mode

– Rate and mode changes will occur

– Device can usually be reprogrammed to former parameters

Elective replacement indicators (ERI) can resemble back-up mode

– Interrogating device will indicate ERI (“Replace Pacer”)

PMT InterventionPMT Intervention

Designed to interrupt a Pacemaker-Mediated Tachycardia

Rate Responsive PacingRate Responsive Pacing

An accelerating or decelerating rate may be perceived as anomalous pacemaker behavior

VVIR / 60 / 120VVIR / 60 / 120

Rate Changes May Occur Due to Rate Changes May Occur Due to Therapy-Specific Device Operation Therapy-Specific Device Operation

Hysteresis

Rate drop response

Mode switching

Sleep function

HysteresisHysteresis

Allows a lower rate between sensed events to occur; paced rate is higher

Lower Rate 70 ppm Hysteresis Rate 50 ppm

Rate Drop ResponseRate Drop Response

Delivers pacing at high rate when episodic drop in rate occurs

– Pacing therapy indicated for patients with neurocardiogenic syncope

Mode SwitchingMode Switching

Device switches from tracking (DDDR) to nontracking (DDIR) mode

Sleep FunctionSleep Function

LowerRate

SleepRate

Rat

e

30mins.

30mins.

Bed Time Wake TimeTime

AV Intervals/Refractory Periods May AV Intervals/Refractory Periods May Appear Anomalous Due to:Appear Anomalous Due to:

Safety pacing

Blanking

Rate-adaptive AV delay

Sensor-varied PVARP

PVC response

Noncompetitive atrial pace (NCAP)

Safety PacingSafety Pacing

Designed to prevent inhibition due to “crosstalk”

– Delivers a ventricular pace 110 ms after an atrial paced event

Ventricular Safety Pace

BlankingBlanking

DDDR / 60 / 125 / 200 / 225

Rate-Adaptive AV DelayRate-Adaptive AV Delay

AV interval shortens as rate increases

PAV delay with no activity: 150 ms PAV with activity: 120 ms

Sensor-Varied PVARPSensor-Varied PVARP

PVARP will shorten as rate increases

Long PVARP with little activityLong PVARP with little activity Shorter PVARP with increased activityShorter PVARP with increased activity

PVC ResponsePVC Response

PVARP will extend to 400 ms

DDD / 60 / 120 PVARP 310 ms

Noncompetitive Atrial Pace (NCAP)Noncompetitive Atrial Pace (NCAP)

Prevents atrial pacing from occurring too close to relative refractory period, which may trigger atrial arrhythmias

A Change in Pacing Modes A Change in Pacing Modes May Be Caused By:May Be Caused By:

Battery depletion indicators (ERI/EOL)

Electrical reset

Mode switching

Noise reversion

Noise ReversionNoise Reversion

Sensing occurring during atrial or ventricular refractory periods will restart the refractory period. Continuous refractory sensing is called noise reversion and will:

– Cause pacing to occur at the sensor-indicated rate for rate-responsive modes

– Cause pacing to occur at the lower rate for non- rate-responsive modes

Noise ReversionNoise Reversion

Note: Adverse patient symptoms may occur as a result of any of the previously mentioned pacing system malfunctions and some pseudomalfunctions.

Management of Patient Symptoms Management of Patient Symptoms May Be Necessary as a Result of:May Be Necessary as a Result of:

Muscle stimulation

Palpitations

Pacemaker syndrome

Shortness of breath due to inappropriate rate response settings

Muscle Stimulation May Be Caused By:Muscle Stimulation May Be Caused By:

Inappropriate electrode placement near diaphragm or nerve plexus

Break in lead insulation

Unipolar pacing

Palpitations May Manifest From:Palpitations May Manifest From:

Pacemaker syndrome

Pacemaker-Mediated Tachycardia (PMT)

Pacemaker SyndromePacemaker Syndrome

“An assortment of symptoms related to the adverse hemodynamic impact

from the loss of AV synchrony.”

Pacemaker SyndromePacemaker Syndrome

Symptoms include:

Dizziness

Presyncope

Chest tightness

Shortness of breath

Neck pulsations

Apprehension/malaise

Fatigue

Pacemaker Syndrome May Be Caused By:Pacemaker Syndrome May Be Caused By:

Loss of capture, sensing

A-V intervals of long duration

Onset of 2:1 block

Single chamber system

Absence of rate increase with exercise

Pacemaker-Mediated Tachycardia (PMT)Pacemaker-Mediated Tachycardia (PMT)

A rapid paced rhythm that can occur with atrial tracking pacemakers

PMT is the Result of:PMT is the Result of:

Retrograde conduction

Tracking fast atrial rates (physiologic or non-physiologic)

Retrograde ConductionRetrograde Conduction

Retrograde Conduction May Be Caused By:Retrograde Conduction May Be Caused By:

Loss of A-V synchrony due to:

– Loss of sensing/capture

– Myopotential sensing

– Premature ventricular contraction (PVC)

– Magnet application

High Rate Atrial Tracking is Caused By:High Rate Atrial Tracking is Caused By:

Supra-ventricular tachyarrhythmias

Atrial oversensing

General Medtronic Pacemaker DisclaimerINDICATIONS

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.

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.

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TroubleshootingTroubleshootingPart IIPart II