Troubleshooting Part I Welcome to Troubleshooting, a course module in CorePace. This module addresses the steps used in troubleshooting-defining the problem, identifying the cause, correcting the problem and verifying the solution.

CorePace Module 4: Troubleshooting 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

Identify the cause of the problem Correct the problem CorePace Module 4: Troubleshooting 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 Troubleshooting must be approached in a systematic manner. Identifying the cause(s) of pacemaker malfunction is essential to implementing an effective solution. Solutions must be verified to ensure that they have effectively resolved the original problem without introducing new concerns.

Defining the Problem and Identifying the Cause

CorePace Module 4: Troubleshooting Potential Problems Identifiable on an ECG Can Generally Be Assigned to Five Categories: Undersensing Oversensing Noncapture No output Pseudomalfunction The causes of undersensing, oversensing, noncapture, lack of output, and pseudomalfunctions vary. However, each of these anomalies compromises the pacemaker’s ability to supplement intrinsic conduction.

CorePace Module 4: Troubleshooting Undersensing An intrinsic depolarization that is present, yet not seen or sensed by the pacemaker P-wave not sensed An intrinsic depolarization occurs in the atrium, but this depolarization is not sensed by the pacemaker. Therefore, the pacemaker sends an inappropriate pacing pulse to that chamber. Undersensing can be thought of as “overpacing.” In this example, an AAI pacemaker is programmed to inhibit the atrial pacing pulse when a P-wave is sensed. Because the P-wave was not sensed, the pacemaker delivered an atrial pulse. If a pacemaker is undersensing, you will not see appropriate atrial sense markers on the marker channel. Atrial Undersensing

Undersensing May Be Caused By: CorePace Module 4: Troubleshooting Undersensing May Be Caused By: Inappropriately programmed sensitivity Lead dislodgment Lead failure: Insulation break; conductor fracture Lead maturation Change in the native signal Insulation breaks may cause undersensing if the insulation break results in the: Reduction of intrinsic beats at the sense amplifier Inability of the amplitude to meet the sensitivity requirement Conductor fracture may cause an open circuit. If intrinsic signals cannot cross the conductor fracture, undersensing will occur. The primary cause of conductor fracture is the chronic stress imposed on the lead as a result of its placement in the subclavian region, and may be reflected in increased impedance readings. During the first week following lead implantation, the amplitude and slew rate may abruptly decline; these values increase to approach implantation values after about 6-8 weeks as the lead matures.1 (Steroid-eluting leads may eliminate the reduction in sensitivity by minimizing the growth of fibrotic tissue near the electrode). Lead dislodgment usually occurs early in the life of the pacemaker before the lead has fibrosed to endocardial tissue. The primary causes of lead dislodgment are: Inadequate initial positioning Patient movement (bringing arms overhead, etc.) Secondary intervention rates for lead dislodgement should be below 2% for ventricular leads and 3% for atrial leads.2 One recent clinical trial reported a lead dislodgement rate of 2.2%.2 Changes in the native signal may be caused by: Myocardial infarction Change in medications (not common) Electrolyte imbalance Undersensing may be caused by an inappropriately programmed setting. 1Hayes DH. Cardiac Pacing and Defibrillation: A Clinical Approach. Armonk, NY: Futura Publishing Company; 2000. Page 453. 2Link MS et al. Complications of dual chamber pacemaker implantation in the elderly. Pacemaker Selection in the Elderly (PASE) Investigators. J Interv Card Electrophysiol. 2:175-179, 1998.

Oversensing The sensing of an inappropriate signal CorePace Module 4: Troubleshooting Oversensing ...Though no activity is present Marker channel shows intrinsic activity... Ventricular Oversensing If a pacemaker is oversensing, you will see signals on the marker channel that do not correspond to the ECG pattern. In this example, the pacemaker recorded a ventricular pulse on the marker channel. However, no activity was demonstrated on the ECG strip. Pauses or intervals longer than the programmed lower rate will occur in single chamber systems. Dual chamber systems may show tracking at the upper rate with atrial oversensing. This ECG exhibits oversensing that may be attributed to: Lead insulation failure (a decrease in lead impedance will be seen) Make-and-break fracture A lead connection problem (Note: The information below transitions into the next slide.) Insulation failure—a common cause of oversensing—occurs when myopotentials are detected at the site of the insulation break. Lead fracture is another common cause of oversensing. As the frayed ends of conductor wires “make and break” contact, the pacemaker senses these “make and break” signals, which results in oversensing. Oversensing may also occur if the lead is loose in the connector block. The sensing of an inappropriate signal Can be physiologic or nonphysiologic

Oversensing May Be Caused By: CorePace Module 4: Troubleshooting Oversensing May Be Caused By: Lead failure Poor connection at connector block Exposure to interference Interference falls under two categories: Electromagnetic interference (EMI) Skeletal myopotentials (noncardiac signals) Oversensing may occur when EMI signals are incorrectly interpreted as P- or R-waves. Sources of EMI are often found in hospitals and include surgical/therapeutic equipment, such as: Electrocautery Transthoracic defibrillation Lithotripsy RF ablation TENS units MRI is generally not recommended for pacemaker patients. Exposure to a magnetic field may produce high-rate pacing that results in ventricular fibrillation and may damage the circuitry of the device. Refer to the device manual for specific information on use of MRI and for additional information and possible contraindications. Concomitant devices, such as ICDs, should be tested to ensure that oversensing between the two devices does not occur. The most common type of myopotential interference is the inappropriate inhibition of pacing pulses as a result of the sensing of myopotentials. Myopotential oversensing is of greater concern with unipolar devices than bipolar devices.

Noncapture is Exhibited By: CorePace Module 4: Troubleshooting Noncapture is Exhibited By: No evidence of depolarization after pacing artifact This ECG strip shows loss of atrial capture, followed by a scheduled ventricular pace. Following the ventricular pulse, the marker channel recorded an intrinsic P-wave. Loss of capture

Noncapture May Be Caused By: CorePace Module 4: Troubleshooting Noncapture May Be Caused By: Lead dislodgment Low output Lead maturation Poor connection at connector block Lead failure In addition to lead dislodgment, lead perforation should be considered as a potential cause of noncapture with acute implants. A poor connection at the connector block usually occurs because the lead has been inadequately secured at implant. The poor connection may be viewed radiographically. As a lead matures and becomes surrounded by fibrotic tissue, the threshold of stimulation decreases, which may result in noncapture.

Less Common Causes of Noncapture May Include: CorePace Module 4: Troubleshooting Less Common Causes of Noncapture May Include: Twiddler’s syndrome Electrolyte abnormalities – e.g., hyperkalemia Myocardial infarction Drug therapy Battery depletion Exit block Twiddler’s syndrome can be identified radiographically. Hyperkalemia, an electrolyte abnormality, is defined by a high serum potassium level and is commonly caused by kidney disease. Hyperkalemia may affect the stimulation threshold. If a myocardial infarction occurs near the tip of the lead, an increase in the stimulation threshold and/or noncapture may occur. Drug therapy may affect capture thresholds and result in significant changes from the patient’s baseline. If the delivered voltage is significantly reduced, advanced stages of battery depletion may result in noncapture. Exit block occurs when the stimulation threshold exceeds the pacemaker’s maximum output.

CorePace Module 4: Troubleshooting No Output Pacemaker artifacts do not appear on the ECG; rate is less than the lower rate When the pacemaker problem is no output, the marker channel shows pacing markers—AP or VP—although no artifact appears on the ECG. No output is defined as the failure to pace. Impulses are generated from the IPG, but is not transferred to the lead. Pacing output delivered; no evidence of pacing spike is seen

No Output May Be Caused By: CorePace Module 4: Troubleshooting No Output May Be Caused By: Poor connection at connector block Lead failure Battery depletion Circuit failure A poor connection at the connector block can result in a lack of output, which can prevent the pacemaker from delivering a pacing pulse. In addition to lead dislodgment, lead perforation should be considered with acute implants as a potential cause of noncapture. Battery depletion can result in a lack of output, which can prevent the pacemaker from delivering a pacing pulse. At generator replacement procedures, (and sometimes at initial implants) the pacemaker pocket may be malformed or too large to accommodate the pacemaker. Air can get trapped in the pocket which, with unipolar devices, will not allow appropriate grounding. No output can result. Circuit failure—more commonly referred to as “pacemaker malfunction”—is very rare.

Pseudomalfunctions Pseudomalfunctions are defined as: Unusual CorePace Module 4: Troubleshooting Pseudomalfunctions Pseudomalfunctions are defined as: Unusual Unexpected Eccentric ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function Pseudomalfunctions should be ruled out as the cause(s) of an anomalous ECG strip before corrective measures are taken.

Pseudomalfunctions May Be Classified Under the Following Categories: CorePace Module 4: Troubleshooting Pseudomalfunctions May Be Classified Under the Following Categories: Rate AV interval/refractory periods Mode

Rate Changes May Occur Due to Normal Device Operation: CorePace Module 4: Troubleshooting 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 Each of these device features has an impact on pacing rates. These rate changes will appear on an ECG strip.

CorePace Module 4: Troubleshooting Magnet Operation Magnet application causes asynchronous pacing at a designated “magnet” rate Magnet operation varies within different product lines and from manufacturer to manufacturer, but will usually involve a rate change when the magnet is applied. The Threshold Margin Test (TMT) is part magnet operation for most of Medtronic’s devices. The following operation describes magnet operation and TMT for most Medtronic devices: Three beats at 100 bpm, followed by a magnet rate of 85 The third beat has an automatic pulse width decrement of 25% (loss of capture would indicate that the stimulation safety margin is inadequate) Dual chamber devices will shorten the AV delay to 100 ms Elective replacement indicators will change the rate from 85 to 65 and the mode from dual to single chamber pacing It is important to remember that magnet modes vary from manufacturer to manufacturer, and from device to device. While recent Medtronic devices use the above rule of thumb, many older devices used the programmed lower rate as the magnet rate, or would decrease the rate by a certain percentage as a battery depletion indicator. Kappa devices have a feature called Extended TMT. Extended TMT is a programmable feature and will operate as follows: TMT is performed at 100 ppm with the pulse width reduced by 25% on the third pulse, 50% on the fifth pulse, and 75% on the seventh pulse. This type of operation is extremely useful in assessing adequate safety margins, by simply using a magnet.

A to A vs. V to V Timing A-A Timing CorePace Module 4: Troubleshooting A to A vs. V to V Timing A to A = 1000 ms A-A Timing V-A = 800 AV = 200 AV = 150 V-A = 850 Atrial rate is held constant at 60 ppm A to A = 1000 ms A to A = 950 ms AV = 200 AV = 150 V-V Timing V-A = 800 V-A = 800 Whether a device employs A–A versus V–V timing is important to know when troubleshooting ECG strips. If a device algorithm uses an A–A timing scheme, it will maintain a stable atrial rate regardless of intrinsic conduction that occurs from the atrium to the ventricle. Ventricular- based timing maintains a stable V–A interval that will allow for paced rates greater than the lower rate limit, if intrinsic conduction occurs between the atrium and ventricle. Atrial rate varies with intrinsic ventricular conduction

CorePace Module 4: Troubleshooting Upper Rate Behavior Pseudo-Wenckebach operation will cause a fluctuation in rate Pseudo-Wenckebach has the characteristic Wenckebach pattern of the PR interval gradually extending beat-to-beat until a ventricular beat is dropped. Pseudo-Wenckebach occurs when the intrinsic atrial rate begins to exceed the upper rate limit. The ventricular response to the intrinsic atrial event cannot exceed the upper rate limit, so the AV interval is lengthened until the upper rate expires and a ventricular pace can be delivered. An atrial sensed event eventually falls into the refractory period and is not seen, and therefore not followed, by a ventricular pace. In this example, the atrial rate has exceeded the upper rate interval, and Wenckebach operation is in effect. Every third P-wave falls into a refractory period and thus is not tracked by the pacemaker.

CorePace Module 4: Troubleshooting Upper Rate Behavior 2:1 block operation will cause a drastic drop in rate 2:1 block is characterized by atrial rates that occur at intervals less than the total atrial refractory period (TARP). Every other P-wave falls into the refractory period and is therefore not proceeded by a paced ventricular event. Patients who experience 2:1 block, particularly those who are active at the time the event occurs, will feel the precipitous drop in rate, which is cut in half.

Electrical Reset and Battery Depletion CorePace Module 4: Troubleshooting 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”) Electrical reset, or “back-up,” modes are usually exhibited by a rate change and often by a mode change. Electrocautery uses radiofrequency current to cut or coagulate tissues. For example, a pacemaker may interpret the radiofrequency signal as an intrinsic event, which would result in inappropriate inhibition of a pacing pulse and could cause the pacemaker to revert to a back-up mode. Defibrillation may damage both the pulse generator and cardiac tissue because it delivers a large amount of electrical energy in the vicinity of the pacemaker. If the pacemaker’s protective mechanisms are overwhelmed by defibrillation, the back-up mode will be activated. Elective replacement indicators are often similar to back-up modes.

CorePace Module 4: Troubleshooting PMT Intervention Designed to interrupt a Pacemaker-Mediated Tachycardia PMT is tachycardia that is induced by pacemaker operation. If PMT occurs, it will affect rate changes as seen on the ECG strip. PMT intervention will extend the PVARP to 400 ms following 8 consecutive events.

Rate Responsive Pacing CorePace Module 4: Troubleshooting Rate Responsive Pacing An accelerating or decelerating rate may be perceived as anomalous pacemaker behavior VVIR / 60 / 120 If a patient is active it is easy to equate rate increases with rate responsive pacing. Some patients may experience “false positive” increases in rate from their sensors. In the case of a piezoelectric crystal, the pacemaker may begin pacing at a faster rate if, for example, the patient is either lying on the side that the pacemaker is implanted on or experiencing a bumpy car ride. Minute ventilation sensors measure the change in respiration rate and tidal volume. If a patient experiences rapid respiration resulting from a cause other than exercise (e.g., hyperventilation), the pacemaker may begin pacing at a faster rate.

Rate Changes May Occur Due to Therapy-Specific Device Operation CorePace Module 4: Troubleshooting Rate Changes May Occur Due to Therapy-Specific Device Operation Hysteresis Rate drop response Mode switching Sleep function Hysteresis, rate drop response, mode switching, and sleep function have varying degrees of impact on the rate.

CorePace Module 4: Troubleshooting Hysteresis Allows a lower rate between sensed events to occur; paced rate is higher Hysteresis Rate 50 ppm Lower Rate 70 ppm Hysteresis provides the capability to maintain the patient’s intrinsic heart rhythm as long as possible, while providing back-up pacing if the intrinsic rhythm falls below the hysteresis rate. Because hysteresis exhibits longer intervals between sensed events, it may be perceived as oversensing.

CorePace Module 4: Troubleshooting Rate Drop Response Delivers pacing at high rate when episodic drop in rate occurs Pacing therapy indicated for patients with neurocardiogenic syncope Rate drop response therapy will exhibit pacing at high rates if detection criteria are met. Rate drop response therapy prevents a precipitous decrease in the rate, which is essential for patients experiencing neurocardiogenic syncope.

CorePace Module 4: Troubleshooting Mode Switching Device switches from tracking (DDDR) to nontracking (DDIR) mode Mode switching is used to prevent the tracking of paroxysmal atrial tachycardias in the DDD/R and VDD modes. In this strip, an atrial arrhythmia is detected and mode switch occurs. After the “MS” designation (for mode switch) in the middle of the strip, a gradual rate decrease occurs as a result of the mode change and the rate smoothing operation.

Sleep Function 30 30 mins. mins. CorePace Module 4: Troubleshooting Lower Rate Sleep 30 mins. 30 mins. A gradual rate decrease to the sleep rate (below the lower rate) will be seen as a programmed bedtime approaches. Bed Time Wake Time Time

AV Intervals/Refractory Periods May Appear Anomalous Due to: CorePace Module 4: Troubleshooting 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) This section describes the impact of safety pacing, blanking, rate-adaptive AV delay, sensor-varied PVARP, PVC response, and NCAP on AV intervals and refractory periods.

Ventricular Safety Pace CorePace Module 4: Troubleshooting Safety Pacing Designed to prevent inhibition due to “crosstalk” Delivers a ventricular pace 110 ms after an atrial paced event Ventricular Safety Pace If atrial undersensing is occurring, ventricular safety pacing may be implemented. For example, if a P-wave is unsensed, the scheduled atrial pace is delivered shortly after the unsensed P-wave. The scheduled atrial pace initiates a PAV of which the first 110 msec is the ventricular safety pacing window.

CorePace Module 4: Troubleshooting Blanking Blanking is the first portion of the refractory period during which the pacemaker is “blind” to any activity. Blanking is designed to prevent multiple detection of a single paced or sensed event by the sense amplifier. However, if the blanking period is too long, it may not sense an event and cause inappropriate pacing. Programmed parameters for the above strip are as follows: DDDR mode, lower rate 60, upper rate 125 ppm, AV delay 200ms, PVARP 225 ms, PAVB period 44 ms. In the strip above, the first complex shows a paced atrial event followed by a conducted R wave. The V-A interval times out to produce an atrial paced event in the second complex, which falls very close to the intrinsic R wave. As the V-A interval times out again, the A pace falls coincident with the intrinsic R- wave. The R-wave is not sensed because it fell into the ventricular blanking period following the atrial paced event. The V-pace was delivered on the T-wave at 200 ms just as programmed. This lack of sensing is often termed “Functional Undersensing.” A change in the lower rate (up or down) or changing the A-V interval (in this example) will allow the R-waves to fall outside the blanking period. DDDR / 60 / 125 / 200 / 225

Rate-Adaptive AV Delay CorePace Module 4: Troubleshooting Rate-Adaptive AV Delay AV interval shortens as rate increases Rate-adaptive AV delay is designed to mimic the intrinsic response to increasing heart rate. In a normal heart, PR intervals decrease as the heart rate increases. Conversely, as the heart rate decreases, PR intervals increase. The rate-adaptive AV delay can be programmed to mimic the normal physiologic response of the PR interval to increasing heart rates. PAV delay with no activity: 150 ms PAV with activity: 120 ms

Long PVARP with little activity Shorter PVARP with increased activity CorePace Module 4: Troubleshooting Sensor-Varied PVARP PVARP will shorten as rate increases The duration of the PVARP will shorten during higher activity when sensor-varied PVARP is enabled. Long PVARP with little activity Shorter PVARP with increased activity

PVC Response PVARP will extend to 400 ms DDD / 60 / 120 PVARP 310 ms CorePace Module 4: Troubleshooting PVC Response PVARP will extend to 400 ms A pacemaker cannot distinguish a PVC from any other ventricular event. PVC response designates a PVC as a ventricular sensed event following a ventricular event with no intervening atrial event. When a PVC is detected, and PVC response is programmed on, the PVARP is extended in order to avoid sensing the retrograde P-wave that could occur as a result of the PVC. A pacemaker defined PVC will initiate a V-A interval. This extended PVARP (if PVC response is on) and subsequent resetting of the timing interval may appear anomalous on an ECG. DDD / 60 / 120 PVARP 310 ms

Noncompetitive Atrial Pace (NCAP) CorePace Module 4: Troubleshooting Noncompetitive Atrial Pace (NCAP) Prevents atrial pacing from occurring too close to relative refractory period, which may trigger atrial arrhythmias If NCAP is implemented, the scheduled atrial pace will be delayed until at least 300 msec have elapsed since the refractory-sensed P-wave occurred. To keep the ventricular rate from experiencing the same delay, the ensuing PAV can be shortened.

A Change in Pacing Modes May Be Caused By: CorePace Module 4: Troubleshooting A Change in Pacing Modes May Be Caused By: Battery depletion indicators (ERI/EOL) Electrical reset Mode switching Noise reversion The Elective replacement indicator (ERI) is designed to alert the clinician at least three months before the battery voltage drops to a level at which noncapture or inconsistent pacing would result. The end of life (EOL) indication is designed to give the patient and physician adequate time to replace the device. Battery depletion may necessitate a mode switch prior to battery failure. For example, the mode may be switched from DDD to VVI or from DOO to VOO.

CorePace Module 4: Troubleshooting 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 non- rate-responsive modes The portion of the refractory period after the blanking period ends is commonly called the “noise sampling period.” A sensed event in the noise sampling period will initiate a new refractory period and blanking period.

Noise Reversion CorePace Module 4: Troubleshooting This example involves a VVI device in a patient with VT. The SR events are occurring due to the rapid ventricular rate. Subsequently, pacing is occurring at the lower rate due to noise reversion.

CorePace Module 4: Troubleshooting Note: Adverse patient symptoms may occur as a result of any of the previously mentioned pacing system malfunctions and some pseudomalfunctions. Adverse symptoms should be recorded and investigated.

Management of Patient Symptoms May Be Necessary as a Result of: CorePace Module 4: Troubleshooting 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 Patient symptoms should be thoroughly investigated to determine the underlying cause.

Muscle Stimulation May Be Caused By: CorePace Module 4: Troubleshooting Muscle Stimulation May Be Caused By: Inappropriate electrode placement near diaphragm or nerve plexus Break in lead insulation Unipolar pacing Diaphragmatic stimulation may occur because of inappropriate lead placement (in the area of the right phrenic nerve) or because of pacing through a thin-walled ventricle resulting in a feeling that may be described as a “hiccup” by the patient. Programming to a lower output may eliminate the diaphragmatic stimulation. Testing the lead at implant by pacing at 10 V is a good indicator as to whether a patient will experience diaphragmatic stimulation post implant. If no diaphragmatic stimulation is experienced at 10 V pacing, it is unlikely that diaphragmatic stimulation will be experienced by the patient post-implant. A break in the lead insulation will allow current to escape and may be felt by the patient. Patients with unipolar systems may experience muscle stimulation near the device.

Palpitations May Manifest From: CorePace Module 4: Troubleshooting Palpitations May Manifest From: Pacemaker syndrome Pacemaker-Mediated Tachycardia (PMT)

CorePace Module 4: Troubleshooting Pacemaker Syndrome “An assortment of symptoms related to the adverse hemodynamic impact from the loss of AV synchrony.” Patients with pacemaker syndrome may experience a wide range of symptoms, ranging from mild to severe.

Pacemaker Syndrome Symptoms include: Dizziness Presyncope CorePace Module 4: Troubleshooting Pacemaker Syndrome Symptoms include: Dizziness Presyncope Chest tightness Shortness of breath Neck pulsations Apprehension/malaise Fatigue While these symptoms vary in severity, their consistent recurrence may indicate pacemaker syndrome.

Pacemaker Syndrome May Be Caused By: CorePace Module 4: Troubleshooting 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 Deleterious hemodynamic effects that occur from loss of AV synchrony or selection of suboptimal pacing parameters can most commonly be associated with pacemaker syndrome. Patients who lose AV synchrony may experience a drop in blood pressure and reduced cardiac output. Relief from pacemaker syndrome is usually achieved by the restoration of AV synchrony.

Pacemaker-Mediated Tachycardia (PMT) CorePace Module 4: Troubleshooting Pacemaker-Mediated Tachycardia (PMT) A rapid paced rhythm that can occur with atrial tracking pacemakers

PMT is the Result of: Retrograde conduction CorePace Module 4: Troubleshooting PMT is the Result of: Retrograde conduction Tracking fast atrial rates (physiologic or non-physiologic) There are two situations that can induce a pacemaker-mediated tachycardia (PMT): Retrograde conduction High rate atrial tracking, caused by atrial flutter or fibrillation or by atrial oversensing

Retrograde Conduction CorePace Module 4: Troubleshooting Retrograde Conduction Even patients who have complete antegrade block may have the ability to conduct retrograde. But having the ability to conduct retrograde is not enough. There must be a situation in which the conduction pathways have had a chance to recover when a ventricular contraction occurs. This diagram shows the initiation of a PMT by a PVC. A retrograde P-wave occurs as a result of the PVC. This retrograde P-wave is sensed outside of the PVARP and starts an SAV interval. When the SAV interval times out, the upper tracking rate has not yet expired so the SAV interval is extended. A ventricular pace is initiated at the end of the upper tracking rate. Because the SAV interval was extended, the AV conduction pathways have recovered and the ventricular pace causes another retrograde P-wave. The sequence continues, which results in a sustained PMT.

Retrograde Conduction May Be Caused By: CorePace Module 4: Troubleshooting 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: CorePace Module 4: Troubleshooting High Rate Atrial Tracking is Caused By: Supra-ventricular tachyarrhythmias Atrial oversensing Atrial fibrillation, atrial flutter, etc. can quickly drive the paced ventricular rate to the upper rate limit. Similarly, oversensing caused by myopotentials or extraneous noise will be tracked, as seen on the ECG above.

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. 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