Troubleshooting pacemakers and implantable cardioverter-defibrillators

PURPOSE OF REVIEW: The purpose of this review is to provide an update on stored diagnostic information furnished by new model pacemakers and implantable cardioverter-defibrillators (ICDs). This information provides crucial information about both device function and arrhythmias discovered with device interrogation and is invaluable when troubleshooting problems with devices. RECENT FINDINGS: The most recent generation of pacemakers and ICDs provides extensive diagnostic data regarding both device and lead function. Regular measurements of lead impedance and pacing thresholds allow for early detection of lead insulation break, fracture, dislodgement, or other problems. Analysis of stored intracardiac electrograms (EGMs) alerts the physician to oversensing and undersensing problems, which may manifest as abnormal device function, inappropriate arrhythmia detection, or inappropriate therapy. Simultaneous dual-chamber EGMs help the clinician diagnose the electrophysiologic mechanism of atrial and ventricular tachyarrhythmias, whether they are sustained, nonsustained, symptomatic, or asymptomatic. Detection and specific diagnosis of arrhythmias with EGMs may determine the need for anticoagulation, institution or change of antiarrhythmic drug therapy, or reprogramming of device detection or therapy parameters. Some devices also have the ability to function as patient-activated monitors. SUMMARY: Better diagnostic data by current pacemakers and ICDs allow for earlier and more accurate identification of device and lead malfunctions as well as better arrhythmia management. In addition, detection of asymptomatic clinically relevant arrhythmias may prompt actions by the physician that can alter clinical outcome.     

Postmortem interrogation and retrieval of implantable pacemakers and defibrillators: a survey of morticians and patients

Introduction: Recent recalls of pacemakers and defibrillators cast a spotlight on product reliability. Universal postmortem device analysis could yield valuable information, but little data exist on the rate and feasibility of device examinations following death. This study investigated how morticians manage pacemakers and defibrillators and surveyed morticians and device patients regarding routine postmortem device interrogation and explantation.
Methods and Results: Seventy-one morticians were surveyed on device interrogation and explantation practices. One hundred fifty patients presenting for routine device interrogation were interviewed regarding preferences for what should be done with devices postmortem and willingness to execute "device advance directives" authorizing analysis and retrieval. The average number of devices annually explanted per mortician was 7 ± 10 (range = 1 to 50). The most common methods of disposal were placement in medical waste (44%) and donation for human reimplantation in developing nations (18%). Only 4% of morticians reported ever returning devices to manufacturers, but 87% agreed that routine explantation and return of devices to manufacturers would be feasible. Eighty-seven percent of device patients had no understanding of how their device would be handled after death. However, a majority (82%) indicated a willingness to have their device interrogated after death, and most (79%) were willing to have it returned to manufacturers. Willingness was not associated with age, sex, time since device implantation, or device type.
Conclusions: Implantable pacemakers and defibrillators are rarely analyzed after patients die. Systematic postmortem device retrieval appears feasible and acceptable to morticians and patients. Further efforts are needed to implement universal postmortem device evaluation.     

Performance of re-used pacemakers and implantable cardioverter defibrillators compared with new devices at Groote Schuur Hospital in Cape Town,South Africa

Objectives

Little is known about the performance of re-used pacemakers and implantable cardioverter defibrillators (ICDs) in Africa. We sought to compare the risk of infection and the rate of malfunction of re-used pacemakers and ICDs with new devices implanted at Groote Schuur Hospital in Cape Town, South Africa.

Methods

This was a retrospective case comparison study of the performance of re-used pacemakers and ICDs in comparison with new devices implanted at Groote Schuur Hospital over a 10-year period. The outcomes were incidence of device infection, device malfunction, early battery depletion, and device removal due to infection, malfunction, or early battery depletion.

Results

Data for 126 devices implanted in 126 patients between 2003 and 2013 were analysed, of which 102 (81%) were pacemakers (51 re-used and 51 new) and 24 (19%) were ICDs (12 re-used and 12 new). There was no device infection, malfunction, early battery depletion or device removal in either the re-used or new pacemaker groups over the median follow up of 15.1 months [interquartile range (IQR), 1.3–36.24 months] for the re-used pacemakers, and 55.8 months (IQR, 20.3–77.8 months) for the new pacemakers. In the ICD group, no device infection occurred over a median follow up of 35.9 months (IQR, 17.0–70.9 months) for the re-used ICDs and 45.7 months (IQR, 37.6–53.7 months) for the new ICDs. One device delivered inappropriate shocks, which resolved without intervention and with no harm to the patient. This re-used ICD subsequently needed generator replacement 14 months later. In both the pacemaker and ICD groups, there were no procedure-non-related infections documented for the respective follow-up periods.

Conclusion

No significant differences were found in performance between re-used and new pacemakers and ICDs with regard to infection rates, device malfunction, battery life and device removal for complications. Pacemaker and ICD re-use is feasible and safe and is a viable option for patients with bradyarrhythmias and tachyarrthythmias.     

Safety of Implantable Pacemakers and Cardioverter Defibrillators in the Magnetic Field of a Novel Remote Magnetic Navigation System

Safety of Pacemakers and ICDs . Introduction: Electromagnetic interference with pacemaker and implantable cardioverter defibrillator (ICD) systems may cause temporary or permanent system malfunction of implanted devices. The aim of this study was to evaluate potential interference of a novel magnetic navigation system with implantable rhythm devices. Methods: A total of 121 devices (77 pacemakers, 44 ICDs) were exposed to an activated NIOBE II® Magnetic Navigation System (Stereotaxis, St. Louis, MO, USA) at the maximal magnetic field strength of 0.1 Tesla and evaluated in vitro with respect to changes in parameter settings of the device, changes of the battery status/detection of elective replacement indication, or alterations of data stored in the device. Results: A total of 115 out of 121 (95%) devices were free of changes in parameter settings, battery status, and internally stored data after repeated exposition to the electromagnetic field of the remote magnetic navigation system. Interference with the magnetic navigation field was observed in 6 pacemakers, resulting in reprogramming to a power‐on‐reset mode with or without detection of the elective replacement indication in 5 devices and abnormal variance of battery status in one device. All pacemakers could be reprogrammed to the initial modes and the battery status proved to be normal some minutes after the pacemakers had been removed from the magnetic field. Conclusion: Interference of a remote magnetic navigation system (at maximal field strength) with pacemakers and ICDs not connected to leads with antitachycardic detection and therapies turned off is rare. Occurring functional abnormalities could be reprogrammed in our sample. An in vitro study will give information about interference of devices connected to leads. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1136‐1141)     

Pacemakers and implantable cardioverter-defibrillators in pediatric patients

The use of pacemakers and implantable cardioverter-defibrillators (ICDs) in infants, children, and patients with congenital heart disease presents unique challenges and considerations. They include uncommon indications for device implantation, innovative approaches to lead implantation and configuration, and age-dependent and disease-specific aspects of device programming. In this review, the current indications for pacemaker and ICD implantation in young patients are discussed, followed by consideration of the approaches to lead and device placement in very small patients and those with complex congenital heart disease, in whom unique problems may be encountered. The limitations of programmability of current pacemakers and ICDs when used in young patients are discussed, followed by an analysis of long-term device follow-up and potential late complications.     

Radiation therapy and cardiac pacemakers]

The number of patients with cardiac pacemakers submitted annually to radiation therapy is increasing. Radiation therapy causes interference in the normal functioning processes, directly by chemical changes in the structure of the device and also by electromagnetic disturbances generated in the process of treatment. The changes in the technology used in the manufacture of cardiac pacemakers after the 70's, with the introduction of complementary metal-oxide semi-conductors (CMOS) in the circuits, drastically increased the chance of dangerous interference in the normal function of cardiac pacemakers occurring when in contact with an ionizing radiation source. The authors briefly describe the mechanisms underlying the radio-induced damage usually observed. A review of the literature on this issue is made and solutions are pointed out to perform safe radiation therapy and minimize the risk of device malfunction.     

Not All Pacemakers Are Created Equal: MRI Conditional Pacemaker and Lead Technology

Due to expanding clinical indications and an aging society there has been an increase in the use of implantable pacemakers. At the same time, due to increased diagnostic yield over other imaging modalities and the absence of ionizing radiation, there has been a surge in demand for magnetic resonance imaging (MRI) assessment, of both cardiac and noncardiac conditions. Patients with an implantable device have a 50–75% chance of having a clinical indication for MRI during the lifetime of their device. The presence of an implantable cardiac device has been seen as a relative contraindication to MRI assessment, limiting the prognostic and diagnostic utility of MRI in many patients with these devices. The introduction of MRI conditional pacemakers will enable more patients to undergo routine MRI assessment without risk of morbidity or device malfunction. This review gives a general overview of the principles and current evidence for the use of MRI conditional implantable cardiac devices. Furthermore, we appraise the differences between those pacemakers currently released to market.     

Potential interference of small neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators

BACKGROUND: Magnetic fields may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets, which are small in size but produce strong magnetic fields, have become widely available in recent years. Therefore, NdFeB magnets may be associated with an emerging risk of device interference. OBJECTIVE: We conducted a clinical study to evaluate the potential of small NdFeB magnets to interfere with cardiac pacemakers and ICDs. METHODS: The effect of four NdFeB magnets (two spherical magnets 8 and 10 mm in diameter, a necklace made of 45 spherical magnets, and a magnetic name tag) was tested in forty-one ambulatory patients with a pacemaker and 29 patients with an ICD. The maximum distance at which the magnetic switch of a device was influenced was observed. RESULTS: Magnetic interference was observed in all patients. The maximum distance resulting in device interference was 3 cm. No significant differences were found with respect to device manufacturer and device types. CONCLUSION: Small NdFeB magnets may cause interference with cardiac pacemakers and ICDs. Patients should be cautioned about the interference risk associated with NdFeB magnets during daily life.     

Permanent pacemaker and implantable cardioverter defibrillator infection: a population-based study

BACKGROUND: The incidence of cardiac device infection is not well understood. Bloodstream infection (BSI) in patients with permanent pacemakers or implantable cardioverter-defibrillators (hereafter, defibrillators) may reflect device infection. METHODS: Retrospective, population-based cohort study of all adult patients with cardiac devices who resided in Olmsted County, Minnesota, from 1975 to 2004. The medical linkage-system of the Rochester Epidemiology Project and standardized criteria were used to identify all cases of BSI and device infection. The incidence of device infection was calculated with person-years of follow-up after device implantation. RESULTS: A total of 1524 patients with cardiac devices were included in the cohort. Total person-time of follow-up was 7578 years. The incidence of definite device infection was 1.9 per 1000 device-years (95% confidence interval [CI], 1.1-3.1). The incidence of pocket infection without BSI was 1.37 per 1000 device-years (95% CI, 0.62-3.05), and pocket infection with BSI or device-related endocarditis 1.14 per 1000 device years (95% CI, 0.47-2.74). The cumulative probability of device infection was higher among patients with defibrillators compared with those with pacemakers, P<.001. Twelve (54.6%) of 22 cases of Staphylococcus aureus BSI had definite or possible cardiac device infection vs 3 (12.0%) of 25 cases of bloodstream infection due to gram-negative bacilli (P = .004). CONCLUSIONS: To our knowledge, this is the first population-based study to describe the incidence of cardiac device infection. Device infection was common during episodes of S aureus BSI. The rate of cardiac device infection was higher in patients with defibrillators than in those with pacemakers.     

Upward bias in estimates of pacemaker reliability: Effect of unreported patient mortality

Objectives. This study attempted to determine the effect of unreported on estimates of pacemaker reliability.Background. The reliability of pacemakers is usualty reported with reference to implant registration data and returned product without censoring when follow-up data are missing.Methods. We studied 73 patients (mean [±SD] age 77 ± 8 years) undergoing implantation of a ventricular-inhibited (VVI) pacemaker who were subsequently found to be at increased risk of experiencing premature pacemaker failure. Survival curves for patients and pacemakers were constructed by the Kaplan-Meier method with appropriate censoring at the time of unrelated death or elective explantation of a normal device. To examine the effect of unreported loss of follow-up data, patient mortality was then ignored, and follow-up for pacemakers without known failure was assumed to continue to the date of analysis.Results. There were 13 device failures, with a median pacemaker survival time of 37 months. Twenty-three patients died, all of causes unrelated to the pacemaker system; median patient survival time was only 44 months. Ignoring this attrition inflated follow-up time from 122 to 188 patient-years and reduced the apparent pacemaker failures at 30 months by almost half, from 37% to only 20%. Modeling the process shows that when the patient mortality rate is more than half the pacemaker failure rate, ignoring censoring inflates the device survival estimate by ≥10% from the median survival onward.Conclusions. When medical device survival curves are generated by implant registration data and returned product analysis, they should be adjusted for unreported loss of follow-up.     

Cardiac device infections complicated by erosion

Background Implantation of pacemakers and implantable cardioverter-defibrillators (ICDs) can be complicated by infection and device erosion. It is unclear if the clinical features of patients who have device erosion differ from those without erosion. Methods We retrospectively examined the records of all patients referred for explantation of a pacemaker or defibrillator from January 2000 to May 2005. We examined demographic variables including age, gender, and body mass index (BMI) as well as clinical variables related to erosion and procedural variables. Results Seventy-two patients with infected pacemakers or ICDs were identified. Of these cases, 30 (42%) developed infection complicated by erosion, of which 8/28 (29%) were related to ICDs, and 22/44 (50%) were related to pacemakers. Conclusions Device erosion was significantly associated with the presence of a non-systemic infection as opposed to cases without erosion. This finding may have implications in the timing of device re-implantation.     

Accuracy of the pacemaker event recorder versus Holter‐ECG to detect both symptomatic and asymptomatic ventricular arrhythmias

1 Background

Although new pacemakers can register cardiac rhythm, few studies were performed evaluating their accuracy in diagnosing ventricular arrhythmias (VA). This study aimed to assess the correlation and agreement between the pacemaker's monitor and the ambulatory Holter in detecting VA.

2 Methods and results

We studied 129 patients with pacemakers, mean age 68.6 ± 19.1 years, 54.8% female. Once Holter monitoring was connected, the pacemakers’ event counters were reset and clocks of both systems were synchronized to register electrocardiograms (ECG) simultaneously. Pacemakers were programmed to detect the lowest ventricular rate and lowest number of sequential beats allowed in their event monitors. After 72 hours, Holter and pacemakers records were analyzed. VA was defined in Holter and event monitor, respectively, as: isolated premature ventricular complexes: “PVC”; pairs: “couplets”; nonsustained ventricular tachycardia (NSVT): “triplets”—3 beats; “runs”—4–8 or > 8 beats, and high ventricular rates (“HVR”)—3–4 beats. Spearman correlations evaluated whether pacemaker and Holter identified the same parameters. Intraclass correlation coefficients (ICCs) and respective 95% confidence intervals were calculated to assess the concordance between methods. The agreement between both systems was low, except for “triplet” and three beats NSVT (ICC = 0.984). The correlation for more than 10 PVC/h was moderate (Kappa = 0.483). When the pacemaker was programmed to detect HVR sequences of three beats lower than 140 bpm (< 140/3), the correlation with NSVT was perfect (r = 1) and agreement was also quite high (ICC = 0.800).

3 Conclusions

Pacemakers' event monitors underestimate the occurrence of ventricular arrhythmias detected by Holter. Standardization of pacemakers’ algorithms is required before using this function for patients' clinical follow‐up.     

Original Article--Outcomes of Pacing in Egyptian Pediatric Population

ObjectivesPermanent pacemakers are widely used in the pediatric population due to congenital and surgically acquired rhythm disturbances. The diversity and complexity of congenital heart diseases make device management a highly individualized procedure in pediatric pacing. We are also faced with special problems in pediatric age group as growth, children’s activity and infection susceptibility. This study aimed to present our institute’s experience in pediatric and adolescent pacemaker implantation and long-term outcomes.MethodsThis cross-sectional observational study included 100 pediatric patients who visited our outpatient clinics at Ain Shams University Hospitals for regular follow up of their previously implanted permanent pacemakers. All patients were subjected to history taking, clinical examination, ECG recording, echocardiography and elaborate device programming. Data about device types, device components’ longevity, subsequent procedures, complications were collected, with comparison between epicardial and endocardial pacemakers.ResultsOur study population ranged in age from 8 months to 18 years (mean 13.12 ± 5.04 years), 51 were males and 53 patients had congenital heart disease. Epicardial pacing represented 26% of our total population using only VVIR pacemakers, while endocardial pacing represented 74% of our population with 58.1% of them being VVIR pacemakers. First battery longevity was higher in endocardial batteries (108 months vs. 60 months, p value: 0.007). First lead longevity was also higher in endocardial leads (105 moths vs. 58 months, p value: 0.006). Complication rate was 25%; 8 patients had early complications (one insulation break in endocardial group). Late complications occurred in 17 patients (10 patients had lead fracture; 9 of them were endocardial, 2 insulation breaks in endocardial leads, 3 patients from epicardial group had lead failure of capture). In total, 16 patients had lead-related complications. There was no statistically significant difference between different lead models regarding lead-related complications.ConclusionPacemakers in children are generally safe, but still having high rates of lead-related complications. Lead failure of capture was more common in epicardial leads. These complications had no relation to the model of the leads. Endocardial pacemakers showed higher first lead and first battery longevity compared to epicardial pacemakers.     

Preventricular Far-Field Sensing in the Atrial Channel of Dual Chamber Pacemakers—An Occasional Cause of Inappropriate Mode Switch

INTRODUCTION AND AIMS OF THE STUDY: Atrial oversensing may trigger false positive mode switch to an asynchronous mode in dual chamber pacemakers. While myopotential oversensing and far-field R wave sensing within the postventricular atrial refractory period are well characterized, data about oversensing (near-field P wave or far-field R wave) within the atrioventricular delay is limited. Aim of the study was to determine the incidence of preventricular oversensing in the atrial channel of current dual chamber pacemakers. METHODS: Consecutive patients with dual chamber pacemakers who were in sinus rhythm and who showed no myopotential oversensing were included in the study. Atrial sensitivity was programmed to the maximal available value and atrioventricular delay was prolonged when necessary for intrinsic atrioventricular conduction. RESULTS: Ten out of 100 (10%) patients showed oversensing within the atrioventricular delay at highest levels of atrial sensitivity, median sensing threshold for the signals was 0.35 mV, and the median coupling interval between preventricular atrial oversensing and the ventricular sensed event was 20 ms. CONCLUSION: The incidence of inappropriate mode switch caused by atrial preventricular oversensing related to near-field P wave or far-field R wave oversensing in dual chamber pacemakers is up to 10%. Interpretation of pacemaker Holters should consider oversensing within the atrioventricular delay as a differential diagnosis to true episodes of atrial tachyarrhythmias.     

Implanted devices and electromagnetic interference: case presentations and review

Electromagnetic interference can cause implanted devices (pacemakers and defibrillators) to malfunction. This article reviews four cases of device interference and provides a review of the literature, and our recommendations for managing these problems.     

Alternating capture of the ventricle and an unusual pacing rate

The recent improvements in technology of cardiac pacing are often responsible for difficult electrocardiograms at follow-up (Gladstone et al., 1987). Therefore, it seems an advantage that most modern pacemakers include diagnostic software functions to explain the pacing behaviour (event markers, intracardiac electrograms...). In this case report an electrocardiogram, showing pacing dysfunction of a physiologic pacemaker with rate response is presented. It was possible to understand what was happening without electrograms, but confirmation of our interpretation of the pacing behaviour was only possible with telemetric data.     

The pacemaker and implantable cardioverter defibrillator recall issue - a Canadian perspective

In 2005, an unprecedented number of recalls were issued on pacemakers and implantable cardioverter defibrillators. While recalls in the cardiac rhythm device industry are not new, the sheer magnitude of potentially affected patients in 2005 led to a great deal of concern, frustration, and even anger. Physicians have, in many instances, been uncertain when (or if) to recommend device replacement in an environment where the magnitude of the risk and the potential consequences of device failure have not been well defined in a timely way. Doctors and patients are now calling for reform of postmarket analysis and reporting mechanisms. The present article provides a uniquely Canadian perspective on this international issue. Potential solutions include the development of a set of realistic and common expectations, a restoration of confidence in postmarket analysis and reporting mechanisms, increased data transparency, and an increased role for patient and physician groups.     

Activity-based rate-adaptive pacemakers under hyperbaric conditions

Objectives The aim of this study was to test a variety of currently available activity-based rate-adaptive pacemakers under hyperbaric conditions.Background Sports divers with pacemakers can dive under certain circumstances. The rate response of activity-sensing pacing under hyperbaric conditions has rarely been evaluated.Materials and methods We manufactured a miniaturized hyperbaric chamber. A pacemaker inside was kept close to the corresponding telemetry wand placed on top of the chamber. An inflation device for coronary balloon angioplasty was used to create hydraulic pressure. Group I pacemakers were exposed to a 30 msw/98 fsw/4 ATA and after a 1-month waiting period to 60 msw/197 fsw-depth/7 ATA. Group II was exposed to only one dive to 60 msw. The electrogram and event marker telemetry were used to monitor the pacing stimuli and measurements were made for case distortion.Results The baseline pacing rate did not change in 27 tests. Return to baseline was shown during 18 tests after transient sensor-driven rate. There was a sensor rate response to manual brief shaking during and following testing. A case distortion was shown in 15 of 29 tests at 60 m.Conclusions Modern accelerometers showed no sensitivity to pressure on the pacemaker can at 30 msw/98 fsw and 60 msw/197 fsw but in some devices responded to pressure changes. There was no pacing dysfunction or suppression of the sensor response despite the high incidence of case distortion at 60 msw/197 fsw. As a general rule, diving should not be allowed at depths greater than 20 msw/65 fsw.     

Periprocedural management of anticoagulation and antiplatelet therapies in patients undergoing electrophysiologic procedures

Electrophysiologic studies, radiofrequency ablation, and device implantations including pacemakers and defibrillators have become essential tools in the armamentarium of electrophysiologists. These procedures are being performed in patients with complex comorbidities, many of whom chronically take anticoagulation or antiplatelet agents. Careful management of anticoagulation before, during, and after electrophysiologic procedures including device implantations is critical to minimize bleeding and thrombotic complications and to optimize patient outcomes.