Test/Observation

Possible Insulation Failure

Possible Conductor Failure

Possible Other System Failure

Effect on Test/ Observation

Pacing Impedance
(Telemetered or Measured Invasively)

Sudden and Significant
Decrease

Sudden and Significant Increase

Pacing Thresholds
(Telemetered/ Programmed or Measured Invasively)

Sudden and Significant Increase, Especially in Bipolar System

Sudden and Significant Increase

Electrograms
(Telemetered or Measured Invasively)

Sudden and Significant Decrease in Amplitudes and/or Slew Rates for P and/or R Waves

Sudden and Significant Decrease or Disappearance of Amplitudes and/or Slew Rates for P and/or R Waves

Waveform Analysis
(Oscillographs of Pacer Artifact from ECG Electrodes)

Sudden Increase in Ratios of Leading-Edge Voltages to Trailing-Edge Voltages (i.e., over 25% increase)

Intermittent or No Pacer Artifacts (Even in Asynchronous Mode)

Improper IPG/Lead Connection

Intermittent or No Pacer Artifacts
(Even in Asynchronous Mode)

Radiographs
(Post-Implant, Recent, Current)

Not Discernible

Visual Observation of Conductor/Connector/ Electrode Fracture (Sometimes Discernible)

Dislodgement or Perforation.
Improper IPG/Lead Connection.

Sometimes Discernible

Visual Inspection
(Invasive)

Insulation Breach and/or Degradation, or Ligature Cut-Through

Not Easily Discernible

Connector Defect or Connector Pulled Apart. Improper IPG/Lead Connection.

Sometimes Discernible

Pectoral Muscle Stimulation

Sudden Onset, Especially in Bipolar System

Connector Defect in Bipolar or Unipolar. Hypersensitivity to Unipolar Pulse Generator Can. Anti-Stim Coating or Protection Deficient.

Phrenic Nerve/
Diaphragmatic Stimulation

Sudden Onset in Bipolar or Unipolar Systems

Perforation or Displacement of Atrial Lead (Phrenic Nerve)

Pacemaker ECG Stimulus
Artifact Size and Morphology Change (May Not Be Possible with Digital ECG)

Sudden Onset and Significant Change, Especially in Bipolar System (Increase in Size)

Sudden Changes, Usually a Decrease in Size

Perforation or Dislodgement. Connector Defect. Improper
IPG/Lead Connection.

Sometimes Discernible

Oversensing
(Intermittent or Continuous)

Sudden Onset, Especially in Bipolar Systems

Physical Contact between the Electrode(s) on the Lead and that of Another Lead. Inappropriate IPG Parameter Setting. Improper IPG/Lead Connection.

Sometimes Discernible

Undersensing
(Intermittent or Continuous)

Sudden Onset in Either Unipolar or Bipolar Systems

Sudden Onset in Either Unipolar or Bipolar Systems

Dislodgement or Perforation. Infarct at Electrode Site. Electrolyte Imbalance. Inappropriate IPG Parameter Setting. Improper IPG/Lead Connection.

Sometimes Discernible

Loss of Capture

See “Pacing Thresholds" Above

See “Pacing Thresholds” Above

See “Pacing Thresholds” Above