ICD leads: design and chronic dysfunctions

Implantable cardioverter defibrillators - the past, present and future

Since their formal introduction in 1980, implantable cardioverter defibrillators (ICDs) have undergone innumerable design modifications through several generations. They are indispensable today in successfully managing fatal ventricular arrhythmias. Their role in averting sudden cardiac death is recognized beyond doubt. Their applications and indications have continuously expanded over the last two decades. This article reviews the salient features in the evolution of ICDs, their current indications, recent advances and future directions. With more advanced detection algorithms, the potential integration with leadless pacing, and the possibility to serve as a remote monitoring device to recognize atrial fibrillation, acute ischemia, or electrolyte imbalance, the application of ICDs is rapidly evolving.

Sensing and Detection Functions in Implantable Cardioverter Defibrillators: The Good, the Bad and the Ugly

Implantable cardioverter defibrillators are small devices that have been proven to be beneficial by preventing sudden cardiac death, whether in primary or secondary prevention. Appropriate functioning of implantable cardioverter defibrillators is mainly dependent on the "good" sensing of ventricular electrogram waves, allowing for the adequate detection of ventricular arrhythmias in order to deliver appropriate therapy of either antitachycardia pacing or by delivering a shock according to the detected rhythm. Basic sensing function in defibrillators is based on detection rate and detection duration; additional parameters that are involved in the process of adequate detection include ventricular electrogram sensing, auto-adjusting sensitivity, supraventricular arrhythmia discrimination criteria, noise detection, and various dedicated algorithms. Defective sensing may result in the delivery of inappropriate therapy (oversensing) or inappropriate withholding of therapy (undersensing); the latter of which may lead to sudden cardiac death. This paper describes different clinical scenarios and programming tips to avoid abnormal or critical clinical situations.

Should Single-Coil Implantable Cardioverter Defibrillator Leads Be Used in all Patients?

The historical preference for dual-coil implantable cardioverter defibrillator leads stems from high defibrillation thresholds associated with old device platforms. The high safety margins generated by contemporary devices have rendered the modest difference in defibrillation efficacy between single- and dual-coil leads clinically insignificant. Cohort data demonstrating worse lead extraction outcomes and higher all-cause mortality have brought the incremental utility of an superior vena cava coil into question. This article summarizes the current literature and re-evaluates the utility of dual-coil leads in the context of modern device technology.

Polymeric Biomaterials for Medical Implants and Devices

In this review article, we focus on the various types of materials used in biomedical implantable devices, including the polymeric materials used as substrates and for the packaging of such devices. Polymeric materials are used because of the ease of fabrication, flexibility, and their biocompatible nature as well as their wide range of mechanical, electrical, chemical, and thermal behaviors when combined with different materials as composites. Biocompatible and biostable polymers are extensively used to package implanted devices, with the main criteria that include gas permeability and water permeability of the packaging polymer to protect the electronic circuit of the device from moisture and ions inside the human body. Polymeric materials must also have considerable tensile strength and should be able to contain the device over the envisioned lifetime of the implant. For substrates, structural properties and, at times, electrical properties would be of greater concern. Section 1 gives an introduction of some medical devices and implants along with the material requirements and properties needed. Different synthetic polymeric materials such as polyvinylidene fluoride, polyethylene, polypropylene, polydimethylsiloxane, parylene, polyamide, polytetrafluoroethylene, poly(methyl methacrylate), polyimide, and polyurethane have been examined, and liquid crystalline polymers and nanocomposites have been evaluated as biomaterials that are suitable for biomedical packaging (section 2). A summary and glimpse of the future trend in this area has also been given (section 3). Materials and information used in this manuscript are adapted from papers published between 2010 and 2015 representing the most updated information available on each material.

Capacity of dental equipment to interfere with cardiac implantable electrical devices

Patients with cardiac implantable electrical devices should take precautions when exposed to electromagnetic fields. Possible interference as a result of proximity to electromagnets or electricity flow from electronic tools employed in clinical odontology remains controversial. The objective of this study was to examine in vitro the capacity of dental equipment to provoke electromagnetic interference in pacemakers and implantable cardioverter defibrillators. Six electronic dental instruments were tested on three implantable cardioverter defibrillators and three pacemakers from different manufacturers. A simulator model, submerged in physiological saline, with elements that reproduced life-size anatomic structures was used. The instruments were analyzed at differing distances and for different time periods of application. The dental instruments studied displayed significant differences in their capacity to trigger electromagnetic interference. Significant differences in the quantity of registered interference were observed with respect to the variables manufacturer, type of cardiac implant, and application distance but not with the variable time of application. The electronic dental equipment tested at a clinical application distance (20 cm) provoked only slight interference in the pacemakers and implantable cardioverter defibrillators employed, irrespective of manufacturer.

Insight into the mechanism of failure of the Riata lead under advisory

BACKGROUND

Cable externalization and insulation abrasion are known to occur with the St Jude Medical Riata leads under advisory. The distribution of these abnormalities and how they relate to clinical presentation have not been well described.

OBJECTIVE

In this study, we sought to determine the relationship between structural lead failure and clinical presentation by using the analysis of returned Riata products in Canada.

METHODS

The analyses of returned Riata products in Canada were obtained from St Jude Medical, Sylmar, CA. These data were correlated with the clinical presentation of patients just before lead removal from service.

RESULTS

As of May 1, 2013, there were 263 returned Riata leads in Canada. Of these, 43 (16.8%) were found to have insulation abrasion that was due to either lead-can or lead-other device interaction (70%) or inside-out abrasion (27.9%). The predilection of lead-to-can abrasion was seen in the Riata 7-F leads (84.2% vs 58.4%; P = .07), while inside-out abrasion was more common in the Riata 8-F leads (37.5% vs 15.8%; P = .12). Electrical abnormalities were frequent (20 of 31 [65.4%]) and most often due to electrical noise (45.2%), although inappropriate shocks were present (25.8%). Death occurred in 1 of 43 (2.3%) of those patients with an insulation defect in the lead-can abrasion group.

CONCLUSION

Lead-can abrasion is the most common form of insulation defect in the Riata group of leads under advisory. Management of this group of leads under advisory should not neglect the issue of lead-can abrasion, in addition to detection of cable externalization.

Generator and lead-related complications of implantable cardioverter defibrillators

BACKGROUND

Increase in the number of patients treated with Implantable Cardioverter Defibrillator (ICD) requests more attention regarding its complications.

OBJECTIVES

This study aimed to assess the generator- and lead-related complications at implantation and during follow-up in the patients who were treated with ICD for primary and secondary prevention reasons.

METHODS

We retrospectively reviewed 255 consecutive patients who underwent transvenous ICD implantation for the first time in a 7-year period and were followed-up for 3 years at Tehran Heart Center. The personal and clinical data of the patients as well as specific data on the ICD implantation were retrieved. The frequency of each of the complications was reported and the study variables were compared between the patients with and without complications using Student's t-test and chi-square test where appropriate. P values less than 0.05 were considered as statistically significant.

RESULTS

Out of a total of 525 implanted leads and 255 implanted devices in 255 patients (mean age = 62.57 ± 13.50 years; male = 196 [76.9%]), complications leading to generator or lead replacement occurred in 32 patients (12.5%). The results revealed no significant difference between the patients with and without complications regarding gender and age (P = 0.206 and P = 0.824, respectively). Also, no significant difference was found between the two groups concerning the ejection fraction (P = 0.271). Lead fracture was the most frequent lead-related complication and was observed in 17 patients (6.6%). Besides, it was mainly observed in the RV leads. Generator-related complications leading to generator replacement were observed in 2 patients (0.7%).

CONCLUSIONS

Despite considerable improvements in the ICD technology, the rate of the ICD complications leading to device replacement and surgical revision, especially those related to the leads, is still clinically important.

Long-term performance of the St Jude Riata 1580-1582 ICD lead family

OBJECTIVE

Safety concerns about the Riata ICD shock lead were recently raised, with insulation failure due to conductor externalisation. Its incidence and presentation were assessed, and predictors of insulation failure and lead survival of the Riata 1580-1582 were studied, retrospectively, before the official recall.

METHODS

All 374 patients at the Erasmus Medical Center between July 2003 and December 2007 with a 1580, 1581 or 1582 shock lead.

RESULTS

The majority of the patients were male (78 %), with a median age of 60 years (IQR 52-70); primary prevention in 61 %. Median follow-up was 60.3 months (IQR 35.5-73.2), with 117 (31 %) patients dying. Electrical abnormalities (mainly noise, 65 %) were observed in 20/257 patients (7.8 %). Definite conductor externalisation was confirmed with fluoroscopy or chest X-ray in 16 patients, and in one after extraction. One patient presented with a drop in the high-voltage impedance trend with a short circuit of the ICD system during defibrillation testing, and needed to be shocked externally. In 8 more patients, conductor externalisation was found during an elective procedure. No predictors of externalisation could be found, except for the use of single coil (p = 0.02). Median time to conductor externalisation was 5 years (IQR 3.1-6.2). Lead externalisation was observed in 5.4 % (95 % CI 3.1-9.3) at 5 years and 22.7 % (95 % CI 13.6-36.6) at 8 years.

CONCLUSION

A high incidence of insulation defects associated with conductor externalisation in the Riata ICD lead family is observed. The mode of presentation is diverse. This type of insulation failure can lead to failure of therapy delivery.

Failure of a novel silicone-polyurethane copolymer (Optim™) to prevent implantable cardioverter-defibrillator lead insulation abrasions

AIM

The purpose of this study was to determine if Optim™, a unique copolymer of silicone and polyurethane, protects Riata ST Optim and Durata implantable cardioverter-defibrillator (ICD) leads (SJM, St Jude Medical Inc., Sylmar, CA, USA) from abrasions that cause lead failure.

METHODS AND RESULTS

We searched the US Food and Drug Administration's (FDA's) Manufacturers and User Device Experience (MAUDE) database on 13 April 2012 using the simple search terms 'Riata ST Optim™ abrasion analysis' and 'Durata abrasion analysis'. Lead implant time was estimated by subtracting 3 months from the reported lead age. The MAUDE search returned 15 reports for Riata ST Optim™ and 37 reports for Durata leads, which were submitted by SJM based on its analyses of returned leads for clinical events that occurred between December 2007 and January 2012. Riata ST Optim™ leads had been implanted 29.1 ± 11.7 months. Eight of 15 leads had can abrasions and three abrasions were caused by friction with another device, most likely another lead. Four of these abrasions resulted in high-voltage failures and one death. One failure was caused by an internal insulation defect. Durata leads had been implanted 22.2 ± 10.6 months. Twelve Durata leads had can abrasions, and six leads had abrasions caused by friction with another device. Of these 18 can and other device abrasions, 13 (72%) had electrical abnormalities. Low impedances identified three internal insulation abrasions.

CONCLUSIONS

Riata ST Optim™ and Durata ICD leads have failed due to insulation abrasions. Optim™ did not prevent these abrasions, which developed ≤ 4 years after implant. Studies are needed to determine the incidence of these failures and their clinical implications.

Improvements in 25 Years of Implantable Cardioverter Defibrillator Therapy

In 1980, Dr. Michel Mirowski and his team inserted the first implantable cardioverter defibrillator (ICD) in a patient. Initially, ICD therapy was not widely accepted, and many physicians actually considered this therapy unethical. Large secondary and primary prevention trials, demonstrating a beneficial effect of ICD therapy in selected patients not only on arrhythmic death but also on all-cause mortality, stimulated a rapid growth in the number of implants and increased patient’s and physician’s acceptance. Improvements in size and weight, arrhythmia discrimination capabilities, battery technology, shock waveform and output, monitoring capabilities and defibrillator electrode technology eventually resulted in the current large number of yearly implants. Today, almost 40 years after the conception of the ICD and 25 years after the first human implant, ICD therapy is the treatment of choice for patients at risk for life-threatening arrhythmias either as secondary or primary prevention. Furthermore, with the more recent addition of resynchronisation therapy to standard ICD therapy, it became possible to treat selected patients with advanced symptoms of heart failure and to lower the risk of sudden death.

Transvenous extraction performance of expanded polytetrafluoroethylene covered ICD leads in comparison to traditional ICD leads in humans

BACKGROUND

In the Endotak Reliance G defibrillating leads (Guidant Corporation, St. Paul, MN, USA), coils are covered with expanded polytetrafluoroethylene (ePTFE) to prevent tissue ingrowth. The aim of the study was to evaluate transvenous extraction performance, outcomes, and fibrotic adherences rate of ePTFE defibrillating leads in comparison to traditional non-ePTFE cardiac defibrillator (ICD) leads.

METHODS

Seventeen consecutive ICD recipients (ePTFE Group A, 16 men, mean age 66 ± 12 years) with 17 Endotak Reliance G dual-coil ICD leads (mean implantation time 23 ± 26 months) underwent a transvenous removal procedure. They were compared with two control groups, including 20 Sprint Quattro 6944 (non-ePTFE Group B; Medtronic Inc., Minneapolis, MN, USA) and 36 Riata 1570 ICD leads (non-ePTFE Group C; St. Jude Medical, St. Paul, USA). The indication for lead extraction was local infection in 35 patients (48%), sepsis in 24 patients (33%), and lead malfunction in 14 patients (19%).

RESULTS

In all groups, all leads were successfully and completely removed without major complications. Overall manual traction was effective in six patients (8%) and more effective in the ePTFE Group (29%) compared to Group B (0%) and Group C (3%) (P = 0.001). Sixty-seven leads (92%) required mechanical dilatation by the venous entry site approach, with a shorter extraction time in the ePTFE Group (5 ± 11 min) compared to Group B (21 ± 22 min) and Group C (16 ± 22 min) (P = 0.003). ePTFE leads showed a lower rate of fibrotic adherences at the superior vena cava level (P = 0.01) without statistically significant differences in the other sites.

CONCLUSIONS

ePTFE-covered leads may be removed more easily and quickly than non-ePTFE leads, requiring less frequently mechanical dilatation.

[ICD lead defects: diagnosis and therapeutical options]

The number of cardioverter/defibrillator (ICD) implantations has been steadily increasing; thus, ICD lead-associated complications are an important issue. No clear recommendations for the diagnosis and management are available. This article gives an overview of how to diagnose and manage an ICD lead defect. Possible therapeutic options are discussed by reviewing the literature.

Atrial and ventricular lead insulation defects with resulting inappropriate shocks and end-of-life of the ICD pulse generator in a young bodybuilder with congenital long-QT-syndrome

We report on a 19-year-old male with a congenital Long-QT syndrome who was admitted to our hospital because of insulation defects of both atrial and ventricular ICD leads resulting in inappropriate delivered shocks and a non-responding pulse generator during telemetrical evaluation. The insulation defects led to multiple arc marks within the ICD pocket and there was a short circuit between denuded leads and the electrically active pulse generator. The high current flow generated sufficient heat to damage several circuits of the generator. A new ICD system was implanted successfully and the postoperative course has been remained uneventful for almost 6 years.

Reducing Mortality With Device Therapy in Heart Failure Patients Without Ventricular Arrhythmias

Use of device therapy to prevent sudden cardiac death in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Three multicenter prospective clinical trials—Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)—were conducted to determine the effectiveness of devices in reducing mortality in patients with heart failure who did not have a history of ventricular arrhythmias. The 3 trials varied in the devices used, the population of patients included, and the study designs. In SCD-HeFT, implantable cardioverter defibrillators were more effective than pharmacological therapy in preventing mortality among patients with mild to moderate heart failure. In COMPANION, cardiac resynchronization therapy alone and cardiac resynchronization therapy plus an implantable cardioverter defibrillator were more effective than optimal drug treatment in reducing morbidity and all-cause mortality in patients with moderate to severe heart failure. In CARE-HF, cardiac resynchronization therapy alone was more effective than optimal drug treatment in reducing all-cause mortality in patients with moderate to severe heart failure. No direct comparison of the devices used has been done. These 3 clinical trials provide clear evidence that device therapy is beneficial for some patients with heart failure, even patients who do not have a history of ventricular arrhythmia.

Necessity for surgical revision of defibrillator leads implanted long-term: causes and management

BACKGROUND

Defibrillator lead malfunction is a potential long-term complication in patients with an implantable cardioverter-defibrillator (ICD). The aim of this study was to determine the incidence and causes of lead malfunction necessitating surgical revision and to evaluate 2 approaches to treat lead malfunction.

METHODS AND RESULTS

We included 1317 consecutive patients with an ICD implanted at 3 European centers between 1993 and 2004. The types and causes of lead malfunction were recorded. If the integrity of the high-voltage part of the lead could be ascertained, an additional pace/sense lead was implanted. Otherwise, the patients received a new ICD lead. Of the 1317 patients, 38 experienced lead malfunction requiring surgical revision and 315 died during a median follow-up of 6.4 years. At 5 years, the cumulative incidence was 2.5% (95% confidence interval, 1.5 to 3.6). Lead malfunction resulted in inappropriate ICD therapies in 76% of the cases. Implantation of a pace/sense lead was feasible in 63%. Both lead revision strategies were similar with regard to lead malfunction recurrence (P=0.8). However, the cumulative incidence of recurrence was high (20% at 5 years; 95% confidence interval, 1.7 to 37.7).

CONCLUSIONS

ICD lead malfunction necessitating surgical revision becomes a clinically relevant problem in 2.5% of ICD recipients within 5 years. In selected cases, simple implantation of an additional pace/sense lead is feasible. Regardless of the chosen approach, the incidence of recurrent ICD lead-related problems after lead revision is 8-fold higher in this population.

Two Different Therapeutic Strategies in ICD Lead Defects: Additional Combined LeadVersus Replacement of the Lead

OBJECTIVES

Implantation of an additional HV-P/S lead versus extraction of the defective HV-P/S lead and implantation of a new one is one possible therapeutic approach in cases of a defective high-voltage pace/sense lead (HV-P/S). No information is available on potential differences in clinical outcome in these different approaches.

METHODS

Between January 2000 and February 2006, 86 patients with HV-P/S lead defect received either an additional transvenous HV-P/S lead (n = 33, group 1) or the HV-P/S lead was replaced (n = 53, group 2). The duration of the initially implanted leads was significantly different in the two groups (7.4 +/- 2.9; group 1 and 4.1 +/- 3.4 years; group 2). The outcome of these two groups of patients was retrospectively analyzed.

RESULTS

Seventy-three patients [85%] survived until the end of follow-up of 29 +/- 15 (group 1) and 33 +/- 21 (group 2) months (P = ns), respectively. Thirteen patients died: six in group 1 and seven in group 2 (P = ns). Fourteen patients experienced perioperative complications (group 1: six; group 2: eight; P = ns). ICD system-related complications occurred in 22 patients (group 1: seven; group two: 15; P = ns). The event-free cumulative survival of patients with additional and replaced HV-P/S lead for postoperative events (including death) after 1, 2, and 3 years was 82%, 70%, 70%, and 86%, 81%, 66%, respectively (P = 0.93).

CONCLUSIONS

Implantation of an additional HV-P/S lead or replacement of the HV-P/S lead in case of HV-P/S lead failure is statistically not different concerning mortality and morbidity. There are no predictors for further lead defects. Implantation of an additional HV-P/S lead should not be recommended in young patients or patients with greater likelihood of living many years. Predictors for death were an age over 70 years and renal insufficiency.

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.

The body electric: a review of literature on implantable cardioverter defibrillators

The number of scientific research studies expounding the efficacy and effectiveness of the implantable cardioverter defibrillator (ICD) in the treatment of cardiac arrhythmias and the prevention of sudden cardiac death (SCD) is prolific. The results from clinical trials that have led to the acceptance of implanting the human heart with an ICD are not as convincing as medical science would have health-care consumers believe. There are many other scientific studies that deal with the hazards involved in heart implantation with an ICD. It is argued in this paper that the impact of heart implantation with an ICD is hazardous to a person's being in significant ways. Heart implantation with an ICD is hazardous to physiological wellbeing, to psychosocial wellbeing, and to quality-of-life wellbeing. It is also argued that although humanistic studies are beginning to filter through the maze of scientific studies, many gaps remain in ICD research. Scientific researchers agree that there remains much needed knowledge for cardiac patients, their family members, and for health professionals.

IEGM-online based evaluation of implantable cardioverter defibrillator therapy appropriateness

Appropriate and inappropriate therapies of implantable cardioverter defibrillators have a major impact on morbidity and quality of life in ICD recipients. Intracardiac electrograms (IEGMs) stored in the ICD have been shown to be essential for differentiating appropriate and inappropriate ICD therapies. The recently introduced third generation of ICD Home Monitoring offers remotely transmitted IEGMs (IEGM-online). Hence, the appropriateness of ICD therapies might be remotely assessed. Validation of these electrograms is currently being performed in the RIONI study. A total of 210 episodes will be collected by about 40 European clinical centers. The study primarily investigates whether the IEGM-online based evaluation of the appropriateness of the ICD's therapeutic decision following a tachyarrhythmia episode detection is equivalent to the evaluation based on the complete ICD episode holter. The evaluation is independently performed by an expert board of three experienced ICD investigators. The equivalence of the two methods is accepted if the conclusions deviate for less than 10% of all evaluated IEGMs. Secondary endpoints investigate the IEGM-online usefulness in more detail. The conclusion of the study is expected by mid of 2007. RIONI has successfully been started for proving the reliability of IEGM-online. The expected results will significantly influence the efficacy of Home Monitoring based patient management.

Development and testing of an algorithm to detect implantable cardioverter-defibrillator lead failure

BACKGROUND

Implantable cardioverter-defibrillator (ICD) lead failures often present as inappropriate shock therapy. An algorithm that can reliably discriminate between ventricular tachyarrhythmias and noise due to lead failure may prevent patient discomfort and anxiety and avoid device-induced proarrhythmia by preventing inappropriate ICD shocks.

OBJECTIVES

The goal of this analysis was to test an ICD tachycardia detection algorithm that differentiates noise due to lead failure from ventricular tachyarrhythmias.

METHODS

We tested an algorithm that uses a measure of the ventricular intracardiac electrogram baseline to discriminate the sinus rhythm isoelectric line from the right ventricular coil-can (i.e., far-field) electrogram during oversensing of noise caused by a lead failure. The baseline measure was defined as the product of the sum (mV) and standard deviation (mV) of the voltage samples for a 188-ms window centered on each sensed electrogram. If the minimum baseline measure of the last 12 beats was <0.35 mV-mV, then the detected rhythm was considered noise due to a lead failure. The first ICD-detected episode of lead failure and inappropriate detection from 24 ICD patients with a pace/sense lead failure and all ventricular arrhythmias from 56 ICD patients without a lead failure were selected. The stored data were analyzed to determine the sensitivity and specificity of the algorithm to detect lead failures.

RESULTS

The minimum baseline measure for the 24 lead failure episodes (0.28 +/- 0.34 mV-mV) was smaller than the 135 ventricular tachycardia (40.8 +/- 43.0 mV-mV, P <.0001) and 55 ventricular fibrillation episodes (19.1 +/- 22.8 mV-mV, P <.05). A minimum baseline <0.35 mV-mV threshold had a sensitivity of 83% (20/24) with a 100% (190/190) specificity.

CONCLUSION

A baseline measure of the far-field electrogram had a high sensitivity and specificity to detect lead failure noise compared with ventricular tachycardia or fibrillation.

Incidence of Complications in Patients with Implantable Cardioverter/Defibrillator Who Receive Additional Transvenous Pace/Sense Leads

BACKGROUND

Implantation of an additional pace/sense (P/S) lead is commonly used in patients with implantable cardioverter/defibrillators (ICDs) to overcome P/S defects of integrated defibrillation leads (HV-P/S leads). No information is available about the clinical outcome and the incidence of complications in these patients.

METHODS

Retrospective analysis was performed in 151 patients (125 male, age 54.9 +/- 13.6 years, LVEF 48.1 +/- 17.8%, CAD in 86 [57%], DCM in 24 [16%], ARVCM in 11 [7%]) who received an additional P/S lead between 1990 and 2002 (54 patients with abdominal and 97 patients with pectoral ICD system). Statistical analysis was done using Kaplan-Meier survival curves.

RESULTS

The average follow-up (FU) after implantation of the additional P/S lead was 43 +/- 27 months. In total 117 patients [77.5%] remain implanted; 22 patients died due to cardiac-related reasons. After a FU of 23 +/- 23 months, 43 patients [28.5%] experienced lead-related problems after implantation of the additional P/S lead: oversensing in 23 [53.5%], insulation defect in 3 [7.0%], fracture in 1 [2.3%], system infection in 4 [9.3%], and defect of the HV-P/S lead in 6 [14.0%] patients. The event-free cumulative survival of the additional P/S lead after 1, 2, and 5 years was 87.0%, 79.8%, and 59.4%, respectively (for pectoral leads: 89.6%, 82.0%, and 60.0%, respectively).

CONCLUSIONS

Implantation of an additional P/S lead in case of failure of an HV-P/S lead is safe. However, it is associated with a substantial rate of complications during FU. Therefore, extraction of damaged defibrillation leads instead of implantation of P/S leads should be favored.

Multiple appropriate and spurious defibrillator shocks in a patient with right ventricular cardiomyopathy

An implantable cardioverter defibrillator (ICD) has been implanted in a 69-year-old patient with arrhythmogenic right ventricular cardiomyopathy (ARVC) for treatment of syncopal ventricular tachycardia (VT). Two types of ICD-related emergencies complicated the clinical course within 15 months. The first arrhythmic event occurred 3 months after ICD implantation as electrical storm with repetitive fast VT, resulting in 87 consecutive shocks at maximal output. Intravenous administration of amiodarone and reprogramming of the device were the measures to control VT. A year later, the patient experienced a cluster of 97 inappropriate shocks. Lead insulation failure produced electrical noise on the ventricular sensing channel and was misidentified as ventricular fibrillation (VF). The depleted ICD and the dual-coil lead were explanted and replaced by a new system. Multiple ICD shocks constitute a medical emergency in ICD patients, which requires immediate device interrogation for differentiation of appropriate and spurious discharges.

Automatic Identification of Clinical Lead Dysfunctions

Implantable cardioverter defibrillators (ICD) lead dysfunctions can cause inappropriate shocks. Current ICDs store lead diagnostics and detected episodes. This stored information with intracardiac electrograms (EGM) and sensed RR interval patterns may characterize the ICD lead performance. The aim of this analysis was to determine the sensitivity and positive predictive value (PPV) of an automatic lead dysfunction identification algorithm. This algorithm uses RR and EGM data to distinguish noncardiac oversensing (OS), for example, due to conductor fracture, and cardiac OS, for example, T-wave OS, from detected episodes. The algorithm also uses lead diagnostics: sensing integrity counter trends (e.g., RR intervals <140 ms), nonsustained tachyarrhythmias episodes with a mean RR <200 ms and impedance trends to identify lead fractures. The PPV was determined using the stored memory from 1,756 ICD patients enrolled in a 13-center long-term lead study with an average follow-up of 18.3 patient-months. Sensitivity was determined in 35 patients who presented with OS or lead fracture-related adverse events confirmed by stored ICD diagnostics. The algorithm sensitivity was 97.1% (34/35). There were 43 additional patients identified by the algorithm without an adverse event. Stored ICD diagnostics confirmed lead dysfunctions in 32 of 43 patients corresponding with an 85.7% PPV (66/77). ICD memory diagnostics and episodes with intracardiac EGM may be used to identify ICD lead dysfunctions with high sensitivity and PPV. This algorithm may be implemented in postprocessing ICD environments (e.g., remote server, programmer) to rapidly identify lead dysfunction prior its clinical manifestation.

An algorithm to predict implantable cardioverter-defibrillator lead failure

OBJECTIVES

The goal of this analysis was to test an algorithm that identifies implantable cardioverter-defibrillator (ICD) lead problems before clinical failure and/or inappropriate therapy.

BACKGROUND

The ICD lead failures typically present as inappropriate shock therapy. Identifying lead failures before their clinical presentation may prevent patient discomfort, improve device longevity, and avoid device-induced proarrhythmia.

METHODS

We tested an algorithm that uses two measures of oversensing and one measure of abnormal impedance to detect a lead failure. The oversensing measures consisted of a counter for RR intervals <140 ms and nonsustained ventricular tachycardia episodes with mean RR interval <200 ms. The impedance measure tracked lead impedances every day and each week. Abnormal impedance was defined as a decrease in impedances or an outlier value compared with baseline. Lead failures were identified when both oversensing measures were met or abnormal impedance and one oversensing measure occurred. The stored data from 696 patients with an ICD were analyzed to determine the sensitivity and specificity of the algorithm to detect lead failures.

RESULTS

Twenty-nine patients demonstrated clinical lead failures with an average of 6 +/- 9 inappropriate shocks per patient. The two oversensing measures used in the algorithm predicted 72% (21 of 29) of the lead failures. Fulfilling at least two of the three impedance and oversensing measures, the sensitivity of our algorithm was 83% (24 of 29) with a 100% (667 of 667) specificity.

CONCLUSION

Oversensing combined with abnormal impedance trends may be used to identify ICD lead failures with high sensitivity and very high specificity.

An Unusual Obstacle in Lead Extraction

This case report deals with an unusual complication in the removal of an active fixation implantable cardioverter defibrillator (ICD) lead. We were not able to pass the stylet beyond the point of lead fracture and this was subsequently found to be due to the stylet passing between the electrode and the outer layer of the lead insulation. The lead was removed by rotation extraction of the entire lead.

Deaths associated with implantable cardioverter defibrillator failure and deactivation reported in the United States Food and Drug Administration Manufacturer and User Facility Device Experience Database

OBJECTIVES

The aim of this study was to understand the causes of implantable cardioverter defibrillator (ICD) failure and complications so that adverse events, including unnecessary death, can be prevented.

BACKGROUND

Sudden death may occur if an ICD fails to treat life-threatening ventricular arrhythmias.

METHODS

The United States Food and Drug Administration Manufacturer and User Facility Device Experience Database was searched for ICD devices and the search term "death." The search yielded 212 death events involving 100 ICD pulse generator and lead models from five manufacturers. These death events were associated with (A) ICD devices for which pulse generator interrogation data and/or the results of the manufacturers analysis of returned devices were available; (B) ICD devices for which neither interrogation data nor the results of the manufacturer's analysis were reported; and (C) normally functioning ICDs that had been deactivated.

RESULTS

(A) A total of 103 (69%) of 150 death events were associated with defective pulse generators or high-voltage leads. Most (34/42 [81%]) apparently sudden or arrhythmic death events were associated with high-voltage lead failure; other deaths were related to pulse generator failure (8/42 [19%]) caused by electronic component defects. (B) A total of 21 of 51 death events were related to a manufacturer's recall; all deaths were arrhythmic but without allegation of device failure. (C) Eleven death events occurred in patients whose pulse generators were found to be off or deactivated; these devices appeared to have been deactivated accidentally or by exposure to magnetic fields, or they were not reactivated after elective surgery.

CONCLUSIONS

ICD device failure and unintended pulse generator deactivation have resulted in unnecessary deaths. Although these deaths may be infrequent, improved devices and follow-up techniques are needed. The magnet deactivation feature probably is unsafe, and health professionals and patients should be cautioned.

Implantable cardioverter/defibrillator therapy in arrhythmogenic right ventricular cardiomyopathy: single-center experience of long-term follow-up and complications in 60 patients

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of ventricular tachycardia (VT) and cardiac arrest in young patients. We hypothesized that treatment with implantable cardioverter/defibrillators (ICDs) is safe and improves the long-term prognosis of ARVC patients at high risk of sudden death.

METHODS AND RESULTS

Sixty patients with ARVC (aged 43+/-16 years) were treated with transvenous ICD systems. Despite a higher number of right ventricular sites tested for adequate lead positions (P<0.05), lower R-wave amplitudes (P<0.001) were achieved in ARVC patients compared with other entities. During follow-up of 80+/-43 months (396 patient-years), event-free survival was 49%, 30%, 26%, and 26% for appropriate ICD therapies and 79%, 64%, 59%, and 56% for potentially fatal VT (>240 bpm) after 1, 3, 5, and 7 years, respectively. Multivariate analysis identified extensive right ventricular dysfunction as an independent predictor of appropriate ICD discharge. Fifty-three adverse events occurred in 37 patients during the perioperative (n=10) or follow-up (n=43) period, mainly related to the leads (n=31 in 21 patients). No lead perforation was observed. Freedom from adverse events was 90%, 78%, 56%, and 42% and freedom from lead-related complications was 95%, 85%, 74%, and 63% after 1, 3, 5, and 7 years, respectively.

CONCLUSIONS

These results strongly suggest an improvement in long-term prognosis by ICD therapy in high-risk patients with ARVC. However, meticulous placement and long-term observation of transvenous lead performance with focus on sensing function are required for the prevention and/or early recognition of disease progression and lead-related morbidity during long-term follow-up of ICD therapy in ARVC.