Internal insulation breaches in an implantable cardioverter-defibrillator lead with redundant conductors

Assessing the Reproducibility of Research Based on the Food and Drug Administration Manufacturer and User Facility Device Experience Data

OBJECTIVE

This article aims to assess the reproducibility of Manufacturer and User Facility Device Experience (MAUDE) data-driven studies by analyzing the data queries used in their research processes.

METHODS

Studies using MAUDE data were sourced from PubMed by searching for "MAUDE" or "Manufacturer and User Facility Device Experience" in titles or abstracts. We manually chose articles with executable queries. The reproducibility of each query was assessed by replicating it in the MAUDE Application Programming Interface. The reproducibility of a query is determined by a reproducibility coefficient that ranges from 0.95 to 1.05. This coefficient is calculated by comparing the number of medical device reports (MDRs) returned by the reproduced queries to the number of reported MDRs in the original studies. We also computed the reproducibility ratio, which is the fraction of reproducible queries in subgroups divided by the query complexity, the device category, and the presence of a data processing flow.

RESULTS

As of August 8, 2022, we identified 523 articles from which 336 contained queries, and 60 of these were executable. Among these, 14 queries were reproducible. Queries using a single field like product code, product class, or brand name showed higher reproducibility (50%, 33.3%, 31.3%) compared with other fields (8.3%, P = 0.037). Single-category device queries exhibited a higher reproducibility ratio than multicategory ones, but without statistical significance (27.1% versus 8.3%, P = 0.321). Studies including a data processing flow had a higher reproducibility ratio than those without, although this difference was not statistically significant (42.9% versus 17.4%, P = 0.107).

CONCLUSIONS

Our findings indicate that the reproducibility of queries in MAUDE data-driven studies is limited. Enhancing this requires the development of more effective MAUDE data query strategies and improved application programming interfaces.

In Vivo Durability of Polyurethane Insulated Implantable Cardioverter Defibrillator (ICD) Leads

The 6935M Sprint Quattro Secure S and 6947M Sprint Quattro Secure are high voltage leads designed to administer a maximum of 40 joules of energy for terminating ventricular tachycardia or ventricular fibrillation. Both leads utilize silicone insulation and a polyurethane outer coating. The inner coil is shielded with polytetrafluoroethylene (PTFE) tubing, while other conductors are enveloped in ethylene tetrafluoroethylene (ETFE), contributing to the structural integrity and functionality of these leads. Polyurethane is a preferred material for the outer insulation of cardiac leads due to its flexibility and biocompatibility, while silicone rubber ensures chemical stability within the body, minimizing inflammatory or rejection responses. Thirteen implantable cardioverter defibrillator (ICD) leads were obtained from the Wright State University Anatomical Gift Program. The as-received devices exhibited varied in vivo implantation durations ranging from less than a month to 89 months, with an average in vivo duration of 41 ± 27 months. Tests were conducted using the Test Resources Q series system, ensuring compliance with ASTM Standard D 1708-02a and ASTM Standard D 412-06a. During testing, a load was applied to the intact lead, with careful inspection for surface defects before each test. Results of load to failure, percentage elongation, percentage elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. The findings revealed no significant differences in these parameters across all in vivo exposure durations. The residual properties of these ICD leads demonstrated remarkable stability and performance over a wide range of in vivo exposure durations, with no statistically significant degradation or performance changes observed.

Accurate detection of lead malfunction from ECG-derived bipolar pacing stimulus amplitude

BACKGROUND

One common mode of lead failure is insulation breach, which may result in myopotential noise and device malfunction. "Pseudo-unipolarization" of bipolar pacing stimuli, as observed from a routine 12-lead electrocardiogram (ECG) due to stimulus current leak, has been observed with insulation breaches.

OBJECTIVE

We sought to characterize this electrocardiographic finding to detect this type of lead malfunction.

METHODS

A total of 138 transvenous leads were analyzed, including 88 with known malfunction and 50 normal leads. The amplitude of a bipolar pacing stimulus on the ECG was recorded and compared with a control data set of newly implanted leads with bipolar stimuli normalized for output.

RESULTS

The malfunction group consisted of 61% right atrium and 39% right ventricle leads with mean pacing output of 2.74 V at 0.5 ms. There was a significant difference in ECG bipolar stimulus amplitudes at time of identification of failure (7.89 ± 7.56 mm/V; P < .001) compared with those of normal leads (0.86 ± 0.41 mm/V). Receiver operating characteristic curve for the prediction of lead malfunction based on absolute ECG amplitude displayed an area under the curve of 0.93 (95% CI, 0.891-0.969). When normalized for programmed stimulus output, a cutoff of 5 mm/V demonstrated a sensitivity of 91% and a specificity of 92% (area under the curve, 0.967; 95% CI, 0.938-0.996).

CONCLUSION

The maximum amplitude of a bipolar pacing stimulus on the ECG is significantly lower in normal functioning leads compared with those with known malfunction. This simply derived variable demonstrated good accuracy at identifying lead failure due to insulation breach.

Clinical performance of implantable cardioverter-defibrillator lead monitoring diagnostics

BACKGROUND

Implantable cardioverter-defibrillator (ICD) lead monitoring diagnostic alerts facilitate the diagnosis of structural lead failure.

OBJECTIVE

The purpose of this study was to prospectively study the performance of Medtronic ICD lead monitoring alerts.

METHODS

A prespecified ancillary substudy, World-Wide Randomized Antibiotic Envelope Infection Prevention Trial, was conducted in patients with an ICD with all available alerts enabled. The investigators reported possible lead system events (LSEs), with or without an alert. An independent committee reviewed all data and classified events as lead failure, other LSE, or nonlead system events (NLEs).

RESULTS

In 4942 patients who were followed for 19.4 ± 8.7 months, there were 124 alerts (65 LSEs, 59 NLEs) and 19 LSEs without an alert. Lead monitoring alerts had 100% sensitivity for the 48 adjudicated lead failures (95% confidence interval 92.6%-100%) and for 10 events adjudicated as either lead failure or connection issue. The positive predictive value of alerts for lead failure was 38.7% (48 of 124). For 34 pace-sense lead failures, an alert that incorporated oversensing was more sensitive than the pacing impedance threshold alert (33 patients [97.1%] vs 9 patients [26.5%]; P < .0001). However, the sensitivity was only 13.6% for lead dislodgments or perforations. Inappropriate shocks occurred in 2 patients with pace-sense lead failure (5.9%). No patient had unnecessary lead replacement for any of the NLEs.

CONCLUSION

In this first real-world prospective study, lead monitoring alerts had 100% sensitivity for identifying lead failures. Although their positive predictive value was modest, no false-positive alerts resulted in an unnecessary lead replacement. For the diagnosis of pace-sense lead failure, an alert for oversensing was more sensitive than a pacing impedance threshold alert.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02277990.

Interpreting device diagnostics for lead failure

Implantable cardioverter-defibrillators (ICDs) incorporate automated, lead-monitoring alerts (alerts) and other diagnostics to detect defibrillation lead failure (LF) and minimize its adverse clinical consequences. Partial conductor fractures cause oversensing, but pacing or high-voltage alerts for high impedance detect only complete conductor fracture. In both pacing and high-voltage insulation breaches, low-impedance alerts require complete breach with metal-to-metal contact. Oversensing alerts for pace-sense LF also require complete breach, but not metal-to metal contact. Electrograms (EGMs) from leads with confirmed fractures have characteristics findings. In insulation breach, however, oversensed EGMs reflect characteristics of the source signal. Oversensing alerts that operate on the sensing channel analyze R-R intervals for 2 patterns typical of LF but uncommon in other conditions: a rapidly increasing count of "nonphysiological" short intervals and rapid "nonsustained tachycardias." These alerts are sensitive but nonspecific. Alerts that compare sensing and shock channels define oversensing as sensed events that do not correlate temporally with EGMs on the shock channel. Their performance depends on implementation. Specific advantages and limitations are reviewed. Most ICDs measure impedance using subthreshold pulses. Patterns in impedance trends provide diagnostic information, whether or not an alert is triggered. Gradual increases in impedance do not indicate structural LF, but they may cause failed defibrillation if shock impedance is high enough. Because impedance-threshold alerts are insensitive, normal impedance trends never exclude LF, but an abrupt increase that triggers an alert almost always indicates a header connection issue or LF. Methods for discriminating connection issues from LF are reviewed.

Improved in vivo stability of silicon-containing polyurethane by fluorocarbon side chain modulation of the surface structure

As a class of widely used biomedical materials, polyurethanes suffer from their insufficient stability in vivo. Although the commercialized silicone-polyetherurethanes (SiPEUs) have demonstrated excellent biostability compared with polyetherurethanes (PEUs) for long-term implantation, the usage of polydimethylsiloxane (PDMS) inevitably decreased the mechanical properties and unexpected breaches were observed. In this study, we introduced a fluorinated diol (FDO) into SiPEU to modulate the molecular interactions and micro-separated morphology. The fluorinated silicon-containing polyurethane (FSiPEU) was achieved with desirable silicone- and fluorine-enriched surfaces and mechanical properties at a low silicon content. As evidenced by in vitro culture of macrophages and in vivo hematoxylin-eosin (H&E) staining, FSiPEU demonstrated a minimized inflammatory response. After implantation in mice for 6 months, the material was devoid of significant surface degradation and had the least chain cleavage of soft segments. The results indicate that FSiPEU could be promising candidates for long-term implantation considering the combination of biostability, biocompatibility and mechanical performances.

A systematic review of the quality of cardiovascular surgery studies that extracted data from the MAUDE database

OBJECTIVE

To investigate opportunities and limitations of using the Manufacturer and User Facility Device Experience (MAUDE) database for cardiovascular surgery research, we analyzed the quality of studies having ever used MAUDE, in the field of cardiovascular surgery.

METHODS

We systematically searched the Cochrane Library, PubMed, EMBASE, and Google Scholar for randomized and nonrandomized studies, from inception to July 2019. Two authors evaluated the quality of the retrieved observational studies, according to the National Institutes of Health quality assessment tool for either case series or cross-sectional studies. These tools quantify the quality of case series and cohorts/cross-sectional studies, respectively, with nine and 14 queries.

RESULTS

Fifty-eight studies were included in the final qualitative review. Of 58 identified studies, 32 were case series, 8 were abstracts of case series, and 13 were reviews or case discussion with an included series from MAUDE. Also, five articles were cross-sectional studies. Of the 32 formal case series, 26 (81%) were found to have poor quality. The most common reasons for a poor quality designation included a lack of consecutive participants, undetermined comparability of participants, and undetermined follow-up adequacy. Only one out of five cross-sectional studies had fair quality; four others were evaluated as poor quality studies.

CONCLUSIONS

Cardiovascular surgery studies using the MAUDE database, whether case series or cross-sectional design, are mostly of poor quality. Their low quality is partly caused by poor study design, but mainly by intrinsic limitations to the MAUDE database: cases recruited are not consecutive; patient characteristics are not detailed enough to allow a meaningful comparison of patient characteristics between different patient entries; outcome measures are unclear; there is a limited follow-up; and time-to-event data are lacking. We conclude that the quality of cardiovascular surgery publications that rely on data from MAUDE could be improved if investigators were to extract all relevant data points from MAUDE entries, then apply standard quality assessment tools in compiling and reporting the data. MAUDE might be improved if it used medical case report standards during the process of reporting and indexing adverse events. To calculate the incidence rate of any adverse event, all event-free cases, as well as all adverse events in patients using a device, are required. Neither of these two variables is available in the MAUDE at the time of writing.

Low-voltage shock impedance measurements: A false sense of security

BACKGROUND

Implantable cardioverter defibrillators use low-voltage shock impedance measurements to monitor the lead integrity. However, previous case reports suggest that low-voltage shock impedance measurements may fail to detect insulation breaches that can cause life-threatening electrical short circuits.

METHODS AND RESULTS

We report six cases of insulation breaches in transvenous defibrillation leads that were not obvious during standard interrogations and testing of the lead beforehand. In two cases, an electrical short circuit during commanded shock delivery for internal electrical cardioversion resulted in a total damage of the ICD generator. In one of these cases, commanded shock delivery induced ventricular fibrillation, which required external defibrillation. In two cases, a shock due to ventricular tachycardia was aborted as the shock impedance was less than 20 Ω. However, in both cases the tiny residual shock energy terminated the ventricular tachycardia. In contrast, in one case the residual energy of the aborted shock did not end ventricular fibrillation induced at defibrillator threshold testing. In one case, the ICD indicated an error code for a short circuit condition detected during an adequate shock delivery.

CONCLUSIONS

This case series illustrates that low-voltage shock impedance measurements can fail to detect insulation breaches. These data suggest that in patients without a contraindication, traditional defibrillator threshold testing or high voltage synchronized shock at the time of device replacement should be considered.

Active Surveillance of the Implantable Cardioverter-Defibrillator Registry for Defibrillator Lead Failures

BACKGROUND

Several defibrillator leads have been recalled due to early lead failure leading to significant patient harm. Confirming the safety of contemporary defibrillator leads is essential to optimizing treatment for patients receiving implantable cardioverter-defibrillators (ICDs). We therefore sought to assess the comparative long-term safety of the 4 most commonly implanted ICD leads within the National Cardiovascular Data Registry ICD Registry.

METHODS AND RESULTS

A propensity-matched survival analysis of the ICD Registry was performed evaluating 4 contemporary ICD leads in patients receiving an ICD system for the first time. All patients in the ICD Registry aged ≥18 years who underwent an implant of an ICD between April 1, 2011 and March 31, 2016 were included. Monitoring of safety began with ICD implant and continued up to 5 years. A meaningful difference in ICD failure rate was defined as twice (or more) the lead failure rate observed in the propensity-matched comparator patients. Among the 374 132 patients who received a new ICD implant, no safety alerts were triggered for the primary safety end point of lead failure for any of the high energy leads studied. Estimated rates of freedom from lead failure at 5 years ranged from 97.7% to 98.9% for the 4 high-energy leads of interest.

CONCLUSIONS

Though limited by incomplete long-term outcomes ascertainment, active surveillance of the ICD Registry suggests that there were no meaningful differences in the rate of ICD high-energy lead survival for the 4 most commonly used high-energy ICD leads.

Impedance in the Diagnosis of Lead Malfunction

Impedance is the ratio of voltage to current in an electrical circuit. Cardiovascular implantable electronic devices measure impedance to assess the structural integrity electrical performance of leads, typically using subthreshold pulses. We review determinants of impedance, how it is measured, variation in clinically measured pacing and high-voltage impedance and impedance trends as a diagnostic for lead failure and lead-device connection problems. We consider the differential diagnosis of abnormal impedance and the approach to the challenging problem of a single, abnormal impedance measurement. Present impedance provides a specific but insensitive diagnostic. For pacing circuits, we review the complementary roles of impedance and more sensitive oversensing diagnostics. Shock circuits lack a sensitive diagnostic. This deficiency is particularly important for insulation breaches, which may go undetected and present with short circuits during therapeutic shocks. We consider new methods for measuring impedance that may increase sensitivity for insulation breaches.

High shocking and pacing impedances due to defibrillation lead calcification

Purpose

We have reported the calcification of Endotak defibrillation leads that required replacement. The aim of this study was to assess calcified Endotak Reliance leads in the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) database and compare them to calcified Sprint Fidelis, Sprint Quattro Secure, Riata, and Durata leads in MAUDE.

Methods

We searched the MAUDE database from 2008 to 2019 for defibrillation lead calcification using the terms “calcium,” “calcification,” and “calcified”. Included were explanted leads whose manufacturers found calcium on the shocking and/or pacing electrode.

Results

The MAUDE search identified 113 calcified defibrillation leads that qualified for the study, including 109 Endotak Reliance leads, 1 Sprint Quattro Secure lead, 2 Durata leads, 1 Riata ST lead, and no Sprint Fidelis lead. The sign of calcification was a gradual increase in shocking or pacing impedance. Average implant time was 7.4 ± 3.1 (range: 1.3–16.5) years. Only Endotak Reliance leads had shocking coil calcification (n = 72; 66.0%) and five (6.9%) of these failed defibrillation threshold (DFT) testing. Distal pacing electrode calcification affected 55 (50.4%) Endotak Reliance leads. The four other leads had pacing ring electrode calcification only.

Conclusion

Endotak Reliance defibrillation leads appear prone to shocking coil and/or distal pacing electrode calcification. High impedances may compromise defibrillation and pacing therapy. Patients who have these leads should be monitored; those exhibiting high shocking impedances should be considered for DFT testing. Lead replacement should be considered for pacemaker-dependent patients whose leads exhibit progressively high impedances.