Conductor Fracture Research Articles

Increasing hazard of Sprint Fidelis implantable cardioverter-defibrillator lead failure

The Medtronic Sprint Fidelis defibrillator lead is prone to fracture and was recalled in 2007 after 665 failures and five reported deaths. Approximately 150,000 patients at risk for sudden death in the United States have Sprint Fidelis leads. The rate of Sprint Fidelis lead failure may be increasing, and physicians are confronted with the decision to replace the lead prophylactically. The purpose of this study was to determine if the hazard of Sprint Fidelis lead failure is changing and to compare its performance to other contemporary implantable cardioverter-defibrillator (ICD) leads. Transvenous ICD leads implanted and followed at our two tertiary-care referral centers between January 2004 and December 2008 were included in the study. Lead failure data were entered prospectively by both centers via the Multicenter Registry. Clinical data were collected prospectively by each center and merged for the purpose of this study. During 5,700 implant years of follow-up (average 1.9 +/- 1.3 years), 94 of 3,037 defibrillator leads failed (1.65%/year), including 72 (8.5%) of 848 Sprint Fidelis leads. The cumulative hazard of Sprint Fidelis failure was significantly greater compared to 2,189 other defibrillator leads (P <.0001), and the hazard of Sprint Fidelis failure accelerated after the first year and continued to increase during the study. In contrast to other defibrillator leads, the Sprint Fidelis failure rate was significantly higher (3.75%/year vs 0.58%/year) and the 3-year estimated survival was significantly lower (87.9% [95% CI 84.8, 90.9] vs 98.5% [95% CI 97.8, 99.3]; P <.0001). The chance that a Sprint Fidelis lead would survive another year decreased progressively during the study. Most Sprint Fidelis failures were caused by pace-sense conductor fracture (n = 63 [87.5%]), which caused inappropriate shocks in 36 of 72 patients. The hazard of Sprint Fidelis lead failure is increasing, whereas the failure rates of other defibrillator leads are low and stable. Physicians should consider these data when managing patients who have Sprint Fidelis leads.

Remote monitoring for prevention of inappropriate implantable cardioverter defibrillator shocks: is there no place like home?

This editorial refers to ‘Potential role of home monitoring to reduce inappropriate shocks in implantable cardioverter-defibrillator patients due to lead failure’ by S. Spencker et al., on page 483 Although the implantable cardioverter defibrillator (ICD) has made a significant impact on prevention of sudden arrhythmic death, important limitations of this therapy remain. Chief among these is the risk of inappropriate shocks, which have been reported in 10‐25% of patients in randomized trials and case registries over 2‐4 years of follow-up. 1 Inappropriate shocks may cause pain, proarrhythmia, and even death in rare cases. Delivery of inappropriate shocks has also been associated with increased late mortality in several large ICD trials. Patients who experience multiple shocks may develop anxiety and other signs of psychological distress, and concern about this complication is commonly expressed by patients. The most common cause of inappropriate shocks is atrial fibrillation, followed by other supraventricular tachycardias, and leadsensing abnormalities. The latter category includes conductor fracture, insulation failure, T-wave oversensing, and myopotential oversensing. 2 A recent study examined 990 patients implanted with a variety of ICD lead models between 1992 and 2005 and found lead failure rates of 15% at 5 years and 40% at 8 years, with a pattern of accelerating annual failure rates over time. 3 One-third of ICD lead failures in this study presented with inappropriate shocks. In patients dependent upon ventricular pacing, ICD lead failure may also lead to symptoms from inhibition of pacing or failure to capture. Concern regarding ICD lead failure has increased recently with the recall of a widely used lead. 4 Manufacturers’ product performance reports suggest early annual lead failure rates of 0.5‐1% of latest generation of ICD leads, while the failure rate of the Sprint Fidelis family is approximately two- to three-fold higher. A 2007 review of the US Food and Drug Administration’s Manufacturer and User Facility Device Experience database found 679 reports of failed Sprint Fidelis leads, 33% of which were associated with inappropriate shocks. 4 Strategies to minimize the risk of inappropriate shocks include using high ventricular tachycardia/ventricular fibrillation rate cutoffs, multiple tachycardia detection zones, longer time to detection, anti-tachycardia pacing, supraventricular tachycardia discrimination algorithms, and medical therapies such as b-blockers and anti-arrhythmic drugs. 5 These strategies are less useful for the prevention of inappropriate shocks caused by ICD lead failure. For this purpose, algorithms have been devised to trigger device alert tones, device vibration, or automatic change in tachycardia detection criteria. 6 None of these algorithms, however, has been prospectively shown to reduce the risk of inappropriate shocks, and improved strategies to prevent inappropriate shocks are clearly needed. Spencker et al. report on their single-centre experience using an automatic wireless remote monitoring system for surveillance of ICD systems. 7 They retrospectively examined 54 patients who underwent ICD lead revision for the failure of the lead over a 6-year period. The 11 patients who had been undergoing daily remote wireless assessment were compared with the 43 patients who had been followed only with quarterly in-office visits. They found that fewer patients undergoing remote monitoring (27.3%) experienced ICD shocks for sensing failure prior to lead revision than those with standard in-office follow-up (46.5%). This trend reached statistical significance when symptomatic pacemaker inhibition was added to the endpoint (27.3% in remote monitoring group vs. 53.4% in the standard follow-up group, P ¼ 0.04). In addition, the authors found that in the standard follow-up patients, evidence of non-sustained oversensing was detected by the ICD a mean of 16 days prior to the onset of symptoms, suggesting that inappropriate shocks could have been avoided in most of these patients, had they been followed with remote monitoring and contacted in a timely fashion.

High sensing integrity counter in a patient with a Sprint Fidelis defibrillation lead: What is the cause?

The Medtronic Sprint Fidelis implantable cardioverter-defibrillator (ICD) lead has a higher than expected incidence of conductor fractures. Their identification is important to the prevention of inappropriate shocks.1,2 The sensing integrity counter, which stores the cumulative number of nonphysiologically short ventricular intervals ≤130 ms, is a diagnostic feature designed to enhance early identification of lead failures.3 Values greater than 300 are abnormal.

A Better Method for Preventing Adverse Clinical Events Caused by Implantable Cardioverter-Defibrillator Lead Fractures?

In October 2007, the Medtronic Sprint Fidelis implantable cardioverter-defibrillator (ICD) lead was voluntarily withdrawn from the market by the manufacturer because of a higher-than-expected fracture rate.1 Most Sprint Fidelis fractures involve the pace-sense component of the lead, which may cause oversensing of electrical artifacts, undersensing of ventricular depolarizations, and/or loss of ventricular capture. Approximately 10% to 20% of Sprint Fidelis fractures involve the high-voltage conductor, which may compromise defibrillation. The most common clinical consequence of pace-sense conductor fracture is inappropriate shocks, which often occur in painful clusters and without warning.2–4 Inappropriate shocks may be proarrhythmic and lethal,5,6 and patients who experience them may suffer psychological sequelae. ICD lead failures are more likely to result in oversensing than pacemakers because the ICD pulse generators use high-sensitivity amplifiers to effectively detect ventricular fibrillation (VF). In this issue of Circulation , Swerdlow et al7 describe a new algorithm that may avoid or reduce inappropriate shocks and other serious adverse events in patients with failed Sprint Fidelis and possibly other high-voltage leads. If this algorithm proves to be safe and effective, it will be an important advance in ICD therapy. Article p 2122 Fracture of a transvenous high-voltage ICD lead was first observed in the original CPI Endotak model in 1988.8 Patients who had this lead suffered multiple inappropriate shocks, and it was withdrawn from clinical trial. Since then, conductor fractures and insulation disruption have challenged engineers and physicians to develop improved designs and implant techniques. Progress has been made, but not without setbacks. The Medtronic Transvene lead, a coaxial polyurethane design introduced in 1993 and implanted in >24 000 patients, exhibited both insulation degradation and conductor fractures; these failures typically appeared ≥4 years after implant and most commonly presented as inappropriate shocks.9 A mismatch between the terminal …

Performance of the St. Jude Medical Riata Leads

Recent attention has been focused on the performance of high-voltage implantable cardioverter-defibrillator (ICD) leads. Lead-related adverse events can be caused by several factors, including patient characteristics, concomitant therapies, implantation technique, access site, and lead design. Few studies have included the number of patients and the follow-up duration necessary to characterize accurately the lead performance and the incidence of lead-related adverse events. This study sought to define the incidence of lead-related adverse events including conductor fracture, insulation damage, perforation, and dislodgement of St. Jude Medical Riata ICD leads. Data from the Advancements in ICD Therapy, OPTIM Lead InsUlation Material (OPTIMUM), Resynchronization HemodYnamic Treatment for Heart Failure Management (RHYTHM), and Post Approval Study (PAS) registries provided data from 7,497 patients with Riata leads. Patients were followed up for a median of 22 months. Adverse events, defined as those that required lead revision, extraction, or replacement, were recorded. Conductor fracture occurred in 0.09%, insulation damage in 0.13%, dislodgement in 0.88%, and perforation in 0.31% of patients, respectively. During more than 22 months of follow-up of over 7,000 Riata leads in 4 prospective registries and clinical trials, the incidence of lead-related adverse events including conductor fracture, insulation damage, dislodgement, and perforation necessitating lead revision, extraction, or replacement is rare.

Permanent Endovenous Pediatric Pacing: Absence of Lead Failure—20 Years Follow‐Up Study

The aim of the study was to analyze endovenous pacing lead survival in pediatric population implanted by cephalic cut down, or by axillary vein puncture. All implantations were performed in total endotracheal anesthesia, by the same surgeon. Implantations of ventricular leads were performed by cephalic vein cut down or by external jugular vein preparation. In dual-chamber pacing, atrial leads were implanted via cephalic vein (along with ventricular lead), by axillary vein puncture or via external jugular vein. All implanted leads were secured by resorbable suture. Over the 20-year follow-up period, 105 children of 5.7 years average age (range 1 day-15 years) were implanted with a permanent endovenous pacing system for congenital or postsurgical complete atrioventricular block or sinus node disease. Within the group, 27 patients (25.7%) weighed less than 10 kg on implantation. A total of 121 endovenous leads were implanted. All ventricular leads were with a passive fixation mechanism, and most of them unipolar (87.6%) and steroid eluting (94.2%). Leads implanted in atrial position were 82% bipolar, predominantly with active fixation (94%), and all steroid eluting. The most frequently used mode of stimulation was VVIR (66.6%). No acute or chronic lead displacement, exit block, sensing problem, lead conductor fracture, insulation defect or infections were observed during the total follow-up of 709 pacing years (average 6.9, range 0-20 years). Implantation of the endovenous leads by preparation of the cephalic or puncture of the axillary vein, with lead fixation by resorbable suture represents a method of choice.

Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead

The Medtronic Sprint Fidelis implantable cardioverter-defibrillator high-voltage lead is prone to fracture. The October 2007 safety advisory recommended lead impedance monitoring to aid in identifying lead fractures. The aim of this single-center study was to examine the effectiveness of impedance monitoring for detecting Sprint Fidelis lead failures before they caused adverse clinical events such as inappropriate shocks. Impedance and sensing information were acquired during routine clinic and CareLink follow-up and at the time of lead failure using the Patient Alert, sensing integrity counter, nonsustained episode, and electrogram features in Medtronic pulse generators. Between September 2004 and February 2008, 17 of 514 Sprint Fidelis leads (3.3%) followed up at our center failed between 11 and 35 months after implantation (mean 23.0 +/- 8.0 months). Fifteen of these failures (88%) were caused by pace-sense conductor fractures, and 2 (12%) were caused by high-voltage conductor defects. Twelve of 15 patients (80%) with pace-sense conductor fractures received inappropriate shocks; of these, 4 had no significant increase in lead impedance before they were shocked, 2 were shocked <3 hours after their lead impedances exceeded the 1,000 Omega audible alert threshold, and 2 patients did not hear the alarm. All pace-sense conductor failures whose sensing function could be evaluated (13 of 15) had oversensing based on stored data, and oversensing usually (11 of 13) preceded impedances changes. Impedance monitoring did not prevent inappropriate shocks in two-thirds of our patients. Thus, pace-sense conductor impedance monitoring as currently implemented does not reliably forewarn patients of a lead malfunction. Consequently, patients who have Sprint Fidelis leads remain at risk for adverse clinical events associated with pace-sense conductor fracture.

Early failure of a small-diameter high-voltage implantable cardioverter-defibrillator lead

We have observed a higher than expected rate of Sprint Fidelis model 6949 lead failures in our practice. The aim of this study was to assess the performance of small-diameter Sprint Fidelis high-voltage ICD leads. The actuarial survival of Sprint Fidelis model 6949 leads implanted at our center was compared with that of the Sprint Quattro Secure model 6947. The United States Food and Drug Administration Manufacturers and User Facility Device Experience (MAUDE) database was searched for Sprint Fidelis models. The survival of 583 Sprint Fidelis 6949 leads implanted at our center between September 2004 and February 2007 was significantly less than 285 Sprint Quattro Secure model 6947 leads implanted by us between November 2001 and February 2007 (P = .005). Six patients presented with Sprint Fidelis lead failure 4-23 months after implant. Five of the six patients experienced multiple inappropriate shocks associated with pace-sense conductor and coil fractures; the sixth patient had a fixation mechanism failure. The MAUDE search rendered reports for 679 Sprint Fidelis leads. The most frequent complaints or observations were inappropriate shocks (33%), high impedance (33%), and fracture (35%). Of 125 leads analyzed by the manufacturer, 62 involved fracture of the pace-sense conductor or coil and the high-voltage (defibrillation) conductor. The Sprint Fidelis high-voltage lead appears to be prone to early failure. Its use should be limited until the failure mechanism is identified and corrected. Patients should be evaluated quarterly, and automatic lead test features should be enabled. While more data are needed, routine prophylactic replacement of intact, normally functioning Sprint Fidelis leads does not appear justified.

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.

Incubation time criterion and the pulsed strength of continua: Fracture, cavitation, and electrical breakdown

Experiments on the dynamic fracture of solids, liquids, conductors, and insulators that is caused by fast intense actions of environment or directed energy fluxes reveal a number of effects indicating a fundamental difference between the fast dynamic rupture (breakdown) of materials and a similar process under slow quasistatic actions. For example, one of the basic problems in testing the dynamic-strength properties of materials is associated with the dependence of the limiting characteristics on the duration, amplitude, and growth rate of an external action, as well as on a number of other factors. Whereas a critical value is a constant for a material in the static case, experimentally determined critical characteristics in dynamics are strongly unstable, and as a result, their behavior becomes unpredictable. The indicated (and some other) features of the behavior of materials subjected to pulsed actions are common for a number of seemingly quite different physical processes, such as dynamic fracture (starting cracks and splitting), cavitation in liquids, and electrical breakdown in solids. In this paper, we analyze examples illustrating typical dynamic effects inherent in the these processes. We propose a unified interpretation for the fracture of solids and liquids and electrical breakdown in insulators using the structural-time approach [1, 2] based on the concept of the fracture incubation time.

Extraction of endocardial implantable cardioverter-defibrillator leads

Despite a growing number of implantable cardioverter-defibrillator (ICD) lead removal indications, there is no consensus about extraction techniques. We applied our experience of pacemaker lead removal to ICD leads using a superior approach with a standard extractor kit, and an inferior approach with a lasso, or a surgical extraction. Fifteen leads were removed in 11 patients during 12 procedures (1 patient was referred twice): 11 right ventricular defibrillation leads, 3 right atrial coils, and 1 atrial lead implanted with a DDD-ICD. The indication for lead extraction was insulation failure (n = 4), conductor fracture (n = 2), abdominal pocket infection (n = 4), lead endocarditis (n = 1), and replacement of an atrial coil by an atrial lead for DDD-R pacing (n = 1). One patient had surgical extraction of 2 leads because of an endocarditis with large vegetations on a DDD-ICD. In 11 other cases, 5 leads were removed using a superior approach with a standard extraction kit and 8 leads were removed by a femoral approach using a lasso alone or added to a pigtail catheter. There was no failure of explantation. One extraction attempt failed with the superior approach but was successful with a secondary inferior approach. The main difficulties encountered were due to tight adherence of the proximal coil to the venous wall and to dislodgment of passive fixation leads from their endocardial insertion. One patient had subclavian vein thrombosis after intervention; no major complication was noted. Ten patients immediately underwent reimplantation. Two patients (1 with an endocarditis and 1 free of ICD therapy for 5 years) did not have reimplantation. During a 4- to 44-month follow-up, no late complication appeared. Thus, ICD lead explantation can be performed with a good success rate, with extraction techniques similar to those used for pacemaker leads.

Study on fracture of silver thick film conductors by acoustic emission

Study on fracture of silver thick film conductors by acoustic emission

Radiological appearances of implantable defibrillator systems

Implantable defibrillator systems have been used in over 20,000 patients worldwide. Such systems use a variety of different electrodes and the identification of these and the recognition of associated problems with them presents a challenge to the radiologist. The appearance of currently available implantable defibrillation systems and the use of radiological examination in patient follow-up and system troubleshooting is discussed based on our experience with a large population of patients receiving these devices. Radiological examination is excellent for demonstrating displacement of distortion of defibrillation electrodes, but in our experience is ineffective for the identification of lead conductor fractures.

Long-term follow up of ventricular endocardial pacing leads. Complications, electrical performance, and longevity of 561 right ventricular leads.

Five hundred and sixty-one endocardial pacing leads implanted in the right ventricle of 502 patients between 1971 and 1990 were followed for up to 17 years regarding their complications, stimulation threshold behavior, and overall longevity. Lead tip dislodgment occurred in 16 leads (2.9%), in 14 of which dislodgement occurred within 2 months after implantation. The incidence of dislodgement was significantly smaller in tined leads than in nontined leads. Lead conductor fracture occurred in 19 leads (3.4%), in 15 of which fracture occurred within 5 years after implantation. Two particular sites of lead fracture were identified; i.e., one within the pacemaker pocket and the other at a particular point in the subclavian vein between the clavicle and the first rib. Fixation ligature in the former site and the venopuncture point for lead insertion in the latter site are thought to be related to lead fracture. Other complications included insulator break in 3 leads (0.5%), exit block in 7 leads (1.2%), and poor sensing in 2 leads (0.4%). The cumulative survival of leads was 94.1 +/- 2.7% (mean +/- 95% confidence interval) at 5 years, 86.3 +/- 6.3% at 10 years, and 74.2 +/- 14.0% at 15 years after implantation. The minimal stimulation threshold, lead impedance and R wave amplitude were all found to be stable for up to 10 years, and there were no tendencies toward higher stimulation threshold during the observation period of this study.

Pacing Lead Survival: Performance of Different Models

Recent reports have shown poor survival of some leads currently in use. Long-term survival analysis of 2,444 leads (1,059 atrial and 1,385 ventricular) implanted in this institution since January 1980, and having at least 1 month of follow-up was performed. The survival of 123 different models was compared with the average survival of all the leads implanted in the corresponding chamber. Failure was defined as inactivation of the lead (electrical abandonment, explant, or cap) due to insulator and/or conductor fracture. The mean follow-up was 33 +/- 32 months. The cumulative survival for different atrial lead models was consistent with the average performance in the atrium. No atrial lead showed better or worse survival compared to the others. In the ventricular group, the Medtronic 4012 lead showed statistically significant poorer survival (P = 0.01) compared with the average survival of the ventricular leads. The Cardiac Pacemakers, Inc. (CPI) 4010 lead showed a nonsignificant (P = 0.12) worse performance than the average for ventricular leads. (1) The Medtronic 4012 had a significantly poorer performance than the rest of the leads. A trend in similar direction was found for the CPI 4010, also in the ventricular group; (2) Atrial lead models showed a stable survival; and (3) Frequent follow-up is required for some leads, especially in pacemaker dependent patients.

Meßgerät zur Erfassung der elektrischen Impedanz des Herzens in der klinischen Anwendung - Device for Cardiac Impedance Measurement in Clinical Use

Changes in the electrical impedance of tissue can indicate structural changes. This suggests a technique for the noninvasive detection of allograft rejection after heart transplantation. The direct electrical connection to the heart and the application of a measuring current to the myocardium requires a high standard of safety. A device was developed for measuring cardiac impedance using a sinusoidal current of 20 microA at a frequency of 15 kHz. The control logic ensures a slow current onset and also an immediate cessation in case of conductor fracture or excessive voltage. Initial results in patients with normal recovery after heart transplantation revealed a rapid drop in impedance to about 70% of the initial value in the 1st 48 hours and then a stable course. In the sole rejection episode observed so far, the impedance increased again to 85% of the initial value. This paper discusses the technical safety requirements and the design of the device, and presents initial results of clinical examinations.

Management of complications associated with a first-generation endocardial defibrillation lead system for implantable cardioverter-defibrillators

An automatic cardioverter-defibrillator could be implanted using an endocardial defibrillation lead system (consisting of a tripolar defibrillation electrode catheter in conjunction with an epicostal patch electrode) in 9 of 10 patients with sustained ventricular tachycardia or ventricular fibrillation. Six lead system complications were observed during a follow-up period of 51 ± 36 weeks. Three catheter electrode conductor fractures occurred and manifested as oversensing and subsequent delivery of inappropriate shocks (1 patient), inability to defibrillate during electrophysiologic testing 3 months after implant (1 patient) and sudden cardiac death (1 patient). Asymptomatic patch electrode conductor fractures were detected on a routine chest roentgenogram in 2 patients. Endocardial defibrillation threshold testing performed at the time of implantation resulted in malfunction of a previously implanted permanent pacemaker pulse generator in 1 patient. Catheter and patch electrode replacement procedures were performed in 3 consenting patients under local anesthesia. Endocardial defibrillation thresholds after lead replacement were comparable to those obtained at time of initial implant. Serial clinical, roentgenographic and electrophysiologic evaluation should be included in follow-up procedures for endocardial defibrillation lead systems. Monitoring for deleterious effects of endocardial defibrillation threshold testing on previously implanted pacemaker systems should be performed at the time of implant and during follow-up. Improved lead designs are necessary for long-term use of endocardial defibrillation electrodes, but replacement procedures are feasible without thoracotomy.

A 20-year study of endocardial pacing lead EMT 588. Lead durability and nature of failure.

A report is presented of 1253 EMT 588 endocardial leads implanted in 1063 patients. The electrode surface area was large (47 mm2) in the 473 leads implanted during 1962-1973, and small (8-12 mm2) in the 780 leads implanted in 1974-1981. Replacement of 245 leads was necessary, in 187 cases due to lead failure and in 58 because of problems with normally functioning leads, such as infection. The highest lead failure rate occurred within the first 6 months after implantation, and was mostly caused by displacement and threshold increase. The dominating cause of late failure was lead lesion. The cumulative lead survival rates for the first and the second series were 88 and 94%, respectively after 1 year, 80 and 91% after 5 years, and 72 and 84% after 9 years. The polyethylene insulation proved to be the most vulnerable part of this lead. Insulation lesions could result in corrosion and/or fracture of the steel conductors. The chronic thresholds were largely stable.