Troubleshooting Part I 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 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: Undersensing Oversensing Noncapture No output Pseudomalfunction Undersensing An intrinsic depolarization that is present, yet not seen or sensed by the pacemaker P-wave 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 Oversensing 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 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: Rate AV interval/refractory periods Mode 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 A-A Timing 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 V-V Timing 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 Tachycardia 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 Hysteresis Rate drop response Mode switching Sleep function Hysteresis 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 30 mins. 30 mins. Rate Lower Rate Sleep Rate Wake Time Bed Time Time AV Intervals/Refractory Periods May Appear Anomalous Due to: Safety pacing Blanking 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 Blanking 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 pseudomalfunctions. Management of Patient Symptoms 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: 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: Dizziness Presyncope Chest tightness Shortness of breath Neck pulsations Apprehension/malaise Fatigue 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 non-physiologic) 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 INDICATIONS 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. Continued in Troubleshooting Part II