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