Troubleshooting Part I

Part I
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
Describe the causes of pacemaker system anomalies
and propose a potential solution
The Steps Used in Troubleshooting Are Simple and
Remain 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
Identifying the Cause
Potential Problems Identifiable on an ECG Can
Generally Be Assigned to Five Categories:
No output
An intrinsic depolarization that is present,
yet not seen or sensed by the pacemaker
not sensed
Atrial Undersensing
Undersensing May Be Caused By:
Inappropriately programmed sensitivity
Lead dislodgment
Lead failure:
– Insulation break; conductor fracture
Lead maturation
Change in the native signal
Marker channel shows
intrinsic activity...
...Though no
activity is present
Ventricular Oversensing
The sensing of an inappropriate signal
– Can be physiologic or nonphysiologic
Oversensing May Be Caused By:
Lead failure
Poor connection at connector block
Exposure to interference
Noncapture is Exhibited By:
 No evidence of depolarization after pacing artifact
Loss of capture
Noncapture May Be Caused By:
Lead dislodgment
Low output
Lead maturation
Poor connection at connector block
Lead failure
Less Common Causes of
Noncapture May Include:
Twiddler’s syndrome
Electrolyte abnormalities – e.g., hyperkalemia
Myocardial infarction
Drug therapy
Battery depletion
Exit block
No 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:
Poor connection at connector block
Lead failure
Battery depletion
Circuit failure
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
Under the Following Categories:
AV interval/refractory periods
Rate Changes May Occur Due to
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 Operation
Magnet application causes asynchronous
pacing at a designated “magnet” rate
A to A vs. V to V Timing
A to A = 1000 ms
AV = 200
V-A = 800
A to A = 1000 ms
AV = 150
V-A = 850
Atrial rate is held constant at 60 ppm
A to A = 1000 ms
AV = 200
V-A = 800
A to A = 950 ms
AV = 150
V-A = 800
Atrial rate varies with intrinsic ventricular conduction
Upper Rate Behavior
Pseudo-Wenckebach operation will cause a
fluctuation in rate
Upper Rate Behavior
 2:1 block operation will cause a drastic
drop in rate
Electrical 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 Intervention
Designed to interrupt a Pacemaker-Mediated
Rate Responsive Pacing
An accelerating or decelerating rate may be
perceived as anomalous pacemaker behavior
VVIR / 60 / 120
Rate Changes May Occur Due to
Therapy-Specific Device Operation
Rate drop response
Mode switching
Sleep function
Allows a lower rate between sensed events to
occur; paced rate is higher
Lower Rate 70 ppm
Hysteresis Rate 50 ppm
Rate Drop Response
Delivers pacing at high rate when episodic drop
in rate occurs
– Pacing therapy indicated for patients with
neurocardiogenic syncope
Mode Switching
Device switches from tracking (DDDR) to
nontracking (DDIR) mode
Sleep Function
Wake Time
Bed Time
AV Intervals/Refractory Periods May
Appear Anomalous Due to:
Safety pacing
Rate-adaptive AV delay
Sensor-varied PVARP
PVC response
Noncompetitive atrial pace (NCAP)
Safety Pacing
Designed to prevent inhibition due to “crosstalk”
– Delivers a ventricular pace 110 ms after an
atrial paced event
Ventricular Safety Pace
DDDR / 60 / 125 / 200 / 225
Rate-Adaptive AV Delay
AV interval shortens as rate increases
PAV delay with no activity: 150 ms
PAV with activity: 120 ms
Sensor-Varied PVARP
PVARP will shorten as rate increases
Long PVARP with little activity
Shorter PVARP with increased activity
PVC Response
PVARP will extend to 400 ms
DDD / 60 / 120 PVARP 310 ms
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
May Be Caused By:
Battery depletion indicators (ERI/EOL)
Electrical reset
Mode switching
Noise reversion
Noise 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 nonrate-responsive modes
Noise Reversion
Note: Adverse patient symptoms may occur as a
result of any of the previously mentioned
pacing system malfunctions and some
Management of Patient Symptoms
May Be Necessary as a Result of:
Muscle stimulation
Pacemaker syndrome
Shortness of breath due to inappropriate rate
response settings
Muscle Stimulation May Be Caused By:
Inappropriate electrode placement near
diaphragm or nerve plexus
Break in lead insulation
Unipolar pacing
Palpitations May Manifest From:
Pacemaker syndrome
Pacemaker-Mediated Tachycardia (PMT)
Pacemaker Syndrome
“An assortment of symptoms related
to the adverse hemodynamic impact
from the loss of AV synchrony.”
Pacemaker Syndrome
Symptoms include:
Chest tightness
Shortness of breath
Neck pulsations
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)
A rapid paced rhythm that can occur with
atrial tracking pacemakers
PMT is the Result of:
Retrograde conduction
Tracking fast atrial rates (physiologic or
Retrograde Conduction
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:
Supra-ventricular tachyarrhythmias
Atrial oversensing
General Medtronic Pacemaker Disclaimer
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.
The Model 9462 Remote Assistant™ is intended for use in combination with a Medtronic implantable pacemaker with Remote Assistant diagnostic capabilities.
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.
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.
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.
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
Continued in
Part II