Improving Device Safety Research Articles

RF-induced heating reduction by minimizing the external portion of the partially in and partially out medical devices under MRI at 1.5 T.

To address the issue of RF-induced heating for partially in and partially out (PIPO) medical devices during 1.5 T MRI scans by proposing a method of minimizing the external portion. A method of tightly winding the external segment of the PIPO device is proposed to minimize the overall device effective reception length during MRI scans to mitigate the RF-induced heating. Two commercially available PIPO medical devices and simplified solid wires were used to demonstrate the concept. RF heating results are compared between typical and minimized-length trajectories under the American Society for Testing and Materials (ASTM) testing procedure. In addition, 16 scaled and validated device models were used in conjuncture with human body numerical simulations within three virtual human models to estimate clinically relevant heating. The wound segments in PIPO devices functioned as a lumped element rather than a receiving antenna, reducing induced energy/heating as compared to the original PIPO devices under typical straight or loop configurations. Minimizing the lead's external portion can reduce the RF-induced heating by significant factors for all studied cases during ASTM phantom measurements and in human body simulations. Our findings show a significant reduction in RF heating by minimizing the external segment, thereby enhancing patient safety during 1.5 T MRI procedures. Although limited to four devices at 1.5 T across two applications, the extent of heating reduction may vary for others. Nonetheless, tightly winding the external segment of PIPO electrodes holds promise for improving device safety under MRI.

Nano-Structuring Strategies of Ti/Sn Oxides Produced from MAX Phases to Achieve Efficient Anodes for Alkaline Ion Batteries

One of the most promising technologies to support lithium-ion batteries (LIB) to follow the growing demand of electrochemical storage devices, particularly for stationary applications, are sodium-ion batteries (NIB). Despite both technologies sharing operating principles, first of all the ion rocking chair mechanism between cathode and anode, it is always difficult to find materials able to exchange ions between battery electrodes quickly and reversibly. While the use of graphite as an anode is a well-established application in LIB; for NIB, hard carbons are currently the most exploited solution, both in laboratory research and upcoming industrial products expected to hit the market in the coming years. The performance of these compounds is heavily reliant on fine control over the synthesis process and the nature of carbonaceous precursors.Over the years, as materials generations change, the anodic side of LIB has also been under study to increase volumetric capacity beyond that of graphite, as well as to improve device safety by reducing the flammability of constituents [1].Another way to develop high-performance LIB and NIB anodes is to exploit the conversion/alloying processes that some compounds/elements exhibit with lithium and sodium. This approach has always been less promising due to strong irreversible capacity lost cycle by cycle due to the poor stability of the materials and the strong volumetric expansions involved. To minimize these phenomena, it is essential to push the grain size of electro-chemically active compounds to the nanometer scale. The strategy used in this work to easily produce nano-structured oxides able to convert/alloy with Li/Na was based on a controlled thermal treatment in air of lamellar carbides known as MAX phases. Specifically, for the first time, powders of Ti3Al(1-x)SnxC2 MAXPhase (synthesized by Spark Plasma Sintering method) were oxidized treated at various temperatures at tested as NIB anode. Samples obtained by varying the Sn concentration and the thermal process parameters were characterized both at a chemical-physical and electrochemical level in half-cells. XRD, SEM, EDX, TEM and Raman (in operando) measurements were used to study the self-nano-structuration process of the oxides on the surface of the original MAX phase [2] and to deeply investigate the storage mechanisms involved. The structural analysis revealed the presence of mixed Ti/Sn oxides with variable composition and structure depending on the process parameters. The aim of the study was to correlate the properties of the oxidized powders with the electrochemical performances in order to maximize the final ion accumulation properties. Preliminary electrochemical tests led to current C/10 capacity values of ≈300 mAh/g (vs Li+/Li) and ≈170 mAh/g (vs Na+/Na) with both cases Coulombic Efficiency >99%.[1] X. Ding, Q. Zhou, X. Li, and X. Xiong, “Fast-charging anodes for lithium ion batteries: progress and challenges,” Chemical Communications, vol. 60, no. 18, pp. 2472–2488, 2024, doi: 10.1039/D4CC00110A.[2] I. Ostroman et al., “Highly Reversible Ti/Sn Oxide Nanocomposite Electrodes for Lithium Ion Batteries Obtained by Oxidation of Ti 3 Al (1‐x) Sn x C 2 Phases,” Small Methods, vol. 7, no. 10, pp. 1–15, Oct. 2023, doi: 10.1002/smtd.202300503.

Thermal performance investigation of latent heat-packed bed thermal energy storage system with axial gas injection

The latent heat-packed bed thermal energy storage system has a broad application prospect in industrial waste heat recovery and solar thermal energy collection. In this work, a novel design with axial gas injections is proposed with the examination for waste heat recovery from the spodumene calcination process. Part of the heat transfer fluid is diverted from the main inlet to the axial inlets, which leads to heat transfer enhancement due to flow rate drop and elevated temperature difference. Compared to the conventional design, axial gas injection leads to an immediate enhancement in temperature uniformity, with a maximum of 64 K decrease in temperature difference, which could reduce thermally induced damage and improve device safety. The axial design also leads to increased charging efficiency by up to 21 %, with the charging efficiency increasing with the number of axial inlets. Further investigation shows charging efficiency is inversely proportional to porosity, with porosity decreasing from 0.5 to 0.3, charging efficiency increases by 15 % at the end of charging, while the round-trip efficiency is on the contrary. Moreover, studies on heat transfer fluid show that elevated mass flow rate leads to decreased charging efficiency and improved round-trip efficiency, which is due to higher entropy generation and enhanced heat transfer rate. For a dedicated application, the packed bed needs to be optimized depending on the thermal performance, safety, and given requirements.

Medical Device Database: Scoping Lifecycle Review

Objectives: This study examines the utilization and lifecycle management of medical device databases in multiple regions including the United States, Europe, Japan, and Canada, and evaluates their public health impact. The objective is to identify best practices, gaps, and challenges in the current systems to inform future improvements and standardization efforts on a global scale.Methods: A comprehensive comparative analysis was conducted on databases in these regions. The analysis focused on the structure, operation, and application of these databases in lifecycle management. Key factors include data collection, integration, utilization throughout the product lifecycle, data accessibility, user interfaces, integration with other healthcare data, regulatory compliance, and public health impacts. Data were collected through literature reviews, policy documents, and expert interviews to provide a robust understanding of each system.Results: Results show reveal significant variations in how regions utilize medical device databases to enhance device safety and efficacy. While all regions aim to improve device safety and public health outcomes, there are notable differences in data accessibility, usage, and management practices. Comprehensive coverage of the medical device lifecycle from pre-market approval to post-market surveillance varies significantly. Integration with regulatory processes and support for public health interventions through detailed tracking and reporting mechanisms also differ widely. Data accessibility and integration with national databases remain challenging. Inconsistent data formats, varying levels of data granularity, and differences in regulatory requirements hinder effective global monitoring and comparison. Despite these challenges, the study highlights the potential for medical device databases to significantly enhance healthcare quality and patient safety.Conclusions: National medical device databases are crucial for improving healthcare quality and safety. They serve as vital tools for identifying issues and informing policy-making. Korea should consider developing a comprehensive database focused on user health protection and safety enhancement, aligned with global standards.

Creation and preclinical evaluation of a novel mussel-inspired, biomimetic, bioactive bone graft scaffold: direct comparison with Infuse bone graft using a rat model of spinal fusion.

Infuse bone graft is a widely used osteoinductive adjuvant; however, the simple collagen sponge scaffold used in the implant has minimal inherent osteoinductive properties and poorly controls the delivery of the adsorbed recombinant human bone morphogenetic protein-2 (rhBMP-2). In this study, the authors sought to create a novel bone graft substitute material that overcomes the limitations of Infuse and compare the ability of this material with that of Infuse to facilitate union following spine surgery in a clinically translatable rat model of spinal fusion. The authors created a polydopamine (PDA)-infused, porous, homogeneously dispersed solid mixture of extracellular matrix and calcium phosphates (BioMim-PDA) and then compared the efficacy of this material directly with Infuse in the setting of different concentrations of rhBMP-2 using a rat model of spinal fusion. Sixty male Sprague Dawley rats were randomly assigned to each of six equal groups: 1) collagen + 0.2 µg rhBMP-2/side, 2) BioMim-PDA + 0.2 µg rhBMP-2/side, 3) collagen + 2.0 µg rhBMP-2/side, 4) BioMim-PDA + 2.0 μg rhBMP-2/side, 5) collagen + 20 µg rhBMP-2/side, and 6) BioMim-PDA + 20 µg rhBMP-2/side. All animals underwent posterolateral intertransverse process fusion at L4-5 using the assigned bone graft. Animals were euthanized 8 weeks postoperatively, and their lumbar spines were analyzed via microcomputed tomography (µCT) and histology. Spinal fusion was defined as continuous bridging bone bilaterally across the fusion site evaluated via µCT. The fusion rate was 100% in all groups except group 1 (70%) and group 4 (90%). Use of BioMim-PDA with 0.2 µg rhBMP-2 led to significantly greater results for bone volume (BV), percentage BV, and trabecular number, as well as significantly smaller trabecular separation, compared with the use of the collagen sponge with 2.0 µg rhBMP-2. The same results were observed when the use of BioMim-PDA with 2.0 µg rhBMP-2 was compared with the use of the collagen sponge with 20 µg rhBMP-2. Implantation of rhBMP-2-adsorbed BioMim-PDA scaffolds resulted in BV and bone quality superior to that afforded by treatment with rhBMP-2 concentrations 10-fold higher implanted on a conventional collagen sponge. Using BioMim-PDA (vs a collagen sponge) for rhBMP-2 delivery could significantly lower the amount of rhBMP-2 required for successful bone grafting clinically, improving device safety and decreasing costs.

Artificial Intelligence in Health Care-Understanding Patient Information Needs and Designing Comprehensible Transparency: Qualitative Study.

Artificial intelligence (AI) is as a branch of computer science that uses advanced computational methods such as machine learning (ML), to calculate and/or predict health outcomes and address patient and provider health needs. While these technologies show great promise for improving healthcare, especially in diabetes management, there are usability and safety concerns for both patients and providers about the use of AI/ML in healthcare management. To support and ensure safe use of AI/ML technologies in healthcare, the team worked to better understand: 1) patient information and training needs, 2) the factors that influence patients' perceived value and trust in AI/ML healthcare applications; and 3) on how best to support safe and appropriate use of AI/ML enabled devices and applications among people living with diabetes. To understand general patient perspectives and information needs related to the use of AI/ML in healthcare, we conducted a series of focus groups (n=9) and interviews (n=3) with patients (n=40) and interviews with providers (n=6) in Alaska, Idaho, and Virginia. Grounded Theory guided data gathering, synthesis, and analysis. Thematic content and constant comparison analysis were used to identify relevant themes and sub-themes. Inductive approaches were used to link data to key concepts including preferred patient-provider-interactions, patient perceptions of trust, accuracy, value, assurances, and information transparency. Key summary themes and recommendations focused on: 1) patient preferences for AI/ML enabled device and/or application information; 2) patient and provider AI/ML-related device and/or application training needs; 3) factors contributing to patient and provider trust in AI/ML enabled devices and/or application; and 4) AI/ML-related device and/or application functionality and safety considerations. A number of participant (patients and providers) recommendations to improve device functionality to guide information and labeling mandates (e.g., links to online video resources, and access to 24/7 live in-person or virtual emergency support). Other patient recommendations include: 1) access to practice devices; 2) connection to local supports and reputable community resources; 3) simplified display and alert limits. Recommendations from both patients and providers could be used by Federal Oversight Agencies to improve utilization of AI/ML monitoring of technology use in diabetes, improving device safety and efficacy.

Frequency of Device-Related Interruptions Using a Scalable Assessment Tool.

Surgical devices are implicated in approximately 15% of intraoperative interruptions and 25% of errors. Device-related interruptions (DRIs) are therefore an important target for surgical quality improvement, but scalable measurement methodologies are lacking. The researchers therefore developed, pilot tested, and refined a simple tool for assessing intraoperative DRIs. Five DRI categories achieved face validity with frontline providers and surgical safety experts: improper/challenging assembly, device failure, loss of sterility, disconnection, and absent/wrong device. A data collection tool was created based on these categories as well as a free-text section to capture emergent DRI categories. After a brief training session, the tool was pilot tested by observers at a large academic referral center. In a sample of 210 operations, observers noted 66 DRIs across 39 cases. DRIs were most common in colorectal (38.0 per 100 cases), gynecologic (33.3 per 100 cases), and hepatopancreatobiliary surgery (32.1 per 100 cases). Device failure accounted for 30.3% of observed DRIs. Three emergent categories were identified: user unfamiliarity with the device (15.2%), video display malfunction (4.5%), and physical breakage of the device (1.5%). Measurement of DRIs by novice observers is a feasible and scalable approach to support quality improvement efforts focusing on surgical devices. This approach could provide actionable insights to improve device safety, such as informing educational and training programs, optimizing surgical tray composition, and improving the physical layout of the operating room.

Risk of Recall Among Medical Devices Undergoing US Food and Drug Administration 510(k) Clearance and Premarket Approval, 2008-2017

The US Food and Drug Administration (FDA) uses 510(k) clearance and premarket approval (PMA) pathways to ensure device safety before marketing. Premarket approval evaluates high-risk medical devices and requires clinical trials, whereas 510(k) clearance evaluates moderate-risk devices and relies on benchtop (nonclinical and biomechanical) and descriptive data. Existing literature suggests that the clinical trials required by PMA are associated with reduced risk of recall compared with devices granted 510(k) clearance. Several investigators have found weaknesses in pivotal PMA trials, raising safety concerns. Furthermore, methodological factors may have led to a previous underestimation of recall risk for devices with PMA. To compare risk of recall and high-risk recall between devices that received 510(k) clearance and those that received PMA and to compare the risk of recall between devices for medical specialties. This cohort study compared devices with 510(k) clearance vs those with PMA that reached the market between January 1, 2008, and December 31, 2017. Two- to 12-year follow-up was obtained from the FDA's 510(k) and PMA medical device database. Orthopedic surgery was chosen arbitrarily as the reference category for analysis between specialties because no baseline exists. Statistical analysis was performed from February 1 to November 1, 2020. The FDA issues recalls for safety concerns. These recalls are stratified into class I, II, and III, with class I representing high-risk issues for serious harm or death. The main outcome was the hazard ratio of any recall and class I recall between devices with PMA and those with 510(k) clearance. The secondary outcome was the recall hazard ratio between specialties with respect to the reference category. A single Cox proportional hazards regression model evaluating the association of medical specialty and FDA approval pathway with the risk of recall was performed. During the study period, 28 246 devices received 510(k) clearance and 310 devices (10.7%) received PMA; 3012 devices (10.7%) with 510(k) clearance and 84 devices (27.1%) with PMA were recalled. A total of 216 devices (0.8%) with 510(k) clearance and 16 devices (5.2%) with PMA had class I recalls. Devices with PMA compared with those with 510(k) clearance had a hazard ratio for recall of 2.74 (95% CI, 2.19-3.44; P < .001) and a hazard ratio for high-risk recall of 7.30 (95% CI, 4.39-12.13; P < .001). Only radiologic devices were associated with an increased risk of recall (hazard ratio, 1.57; 95% CI, 1.32-1.87; P < .001), whereas 6 specialties were assocated with a decreased risk compared with the orthopedic reference category: general and plastic surgery, otolaryngology, obstetrics and gynecology, physical medicine, hematology, and general hospital. This study suggests that high-risk medical devices approved via PMA are associated with a greater risk of recall than previously reported. Most recalls are for devices with 510(k) clearance, also raising safety concerns. Strengthening postmarketing surveillance strategies and pivotal trials may improve device safety.

Personal protective equipment related skin reactions in healthcare professionals during COVID-19.

Since the outbreak of COVID‐19 pandemic, clinicians have had to use personal protective equipment (PPE) for prolonged periods. This has been associated with detrimental effects, especially in relation to the skin health. The present study describes a comprehensive survey of healthcare workers (HCWs) to describe their experiences using PPE in managing COVID‐19 patients, with a particular focus on adverse skin reactions. A 24‐hour prevalence study and multi‐centre prospective survey were designed to capture the impact of PPE on skin health of hospital staff. Questionnaires incorporated demographics of participants, PPE type, usage time, and removal frequency. Participants reported the nature and location of any corresponding adverse skin reactions. The prevalence study included all staff in intensive care from a single centre, while the prospective study used a convenience sample of staff from three acute care providers in the United Kingdom. A total of 108 staff were recruited into the prevalence study, while 307 HCWs from a variety of professional backgrounds and demographics participated in the prospective study. Various skin adverse reactions were reported for the prevalence study, with the bridge of the nose (69%) and ears (30%) being the most affected. Of the six adverse skin reactions recorded for the prospective study, the most common were redness blanching (33%), itchiness (22%), and pressure damage (12%). These occurred predominantly at the bridge of the nose and the ears. There were significant associations (P < .05) between the adverse skin reactions with both the average daily time of PPE usage and the frequency of PPE relief. The comprehensive study revealed that the use of PPE leads to an array of skin reactions at various facial locations of HCWs. Improvements in guidelines are required for PPE usage to protect skin health. In addition, modifications to PPE designs are required to accommodate a range of face shapes and appropriate materials to improve device safety.

Multipronged Approach to Combat Catheter-Associated Infections and Thrombosis by Combining Nitric Oxide and a Polyzwitterion: a 7 Day In Vivo Study in a Rabbit Model.

The development of nonfouling and antimicrobial materials has shown great promise for reducing thrombosis and infection associated with medical devices with aims of improving device safety and decreasing the frequency of antibiotic administration. Here, the design of an antimicrobial, anti-inflammatory, and antithrombotic vascular catheter is assessed in vivo over 7 d in a rabbit model. Antimicrobial and antithrombotic activity is achieved through the integration of a nitric oxide donor, while the nonfouling surface is achieved using a covalently bound phosphorylcholine-based polyzwitterionic copolymer topcoat. The effect of sterilization on the nonfouling nature and nitric oxide release is presented. The catheters reduced viability of Staphylococcus aureus in long-term studies (7 d in a CDC bioreactor) and inflammation in the 7 d rabbit model. Overall, this approach provides a robust method for decreasing thrombosis, inflammation, and infections associated with vascular catheters.

Transmission of Mobile Colistin Resistance (mcr-1) by Duodenoscope.

Clinicians increasingly utilize polymyxins for treatment of serious infections caused by multidrug-resistant gram-negative bacteria. Emergence of plasmid-mediated, mobile colistin resistance genes creates potential for rapid spread of polymyxin resistance. We investigated the possible transmission of Klebsiella pneumoniae carrying mcr-1 via duodenoscope and report the first documented healthcare transmission of mcr-1-harboring bacteria in the United States. A field investigation, including screening targeted high-risk groups, evaluation of the duodenoscope, and genome sequencing of isolated organisms, was conducted. The study site included a tertiary care academic health center in Boston, Massachusetts, and extended to community locations in New England. Two patients had highly related mcr-1-positive K. pneumoniae isolated from clinical cultures; a duodenoscope was the only identified epidemiological link. Screening tests for mcr-1 in 20 healthcare contacts and 2 household contacts were negative. Klebsiella pneumoniae and Escherichia coli were recovered from the duodenoscope; neither carried mcr-1. Evaluation of the duodenoscope identified intrusion of biomaterial under the sealed distal cap; devices were recalled to repair this defect. We identified transmission of mcr-1 in a United States acute care hospital that likely occurred via duodenoscope despite no identifiable breaches in reprocessing or infection control practices. Duodenoscope design flaws leading to transmission of multidrug-resistant organsisms persist despite recent initiatives to improve device safety. Reliable detection of colistin resistance is currently challenging for clinical laboratories, particularly given the absence of a US Food and Drug Administration-cleared test; improved clinical laboratory capacity for colistin susceptibility testing is needed to prevent the spread of mcr-carrying bacteria in healthcare settings.

Advancing medical device innovation through collaboration and coordination of structured data capture pilots: Report from the Medical Device Epidemiology Network (MDEpiNet) Specific, Measurable, Achievable, Results-Oriented, Time Bound (SMART) Think Tank

The Medical Device Epidemiology Network (MDEpiNet) is a public private partnership (PPP) that provides a platform for collaboration on medical device evaluation and depth of expertise for supporting pilots to capture, exchange and use device information for improving device safety and protecting public health. The MDEpiNet SMART Think Tank, held in February, 2013, sought to engage expert stakeholders who were committed to improving the capture of device data, including Unique Device Identification (UDI), in key electronic health information. Prior to the Think Tank there was limited collaboration among stakeholders beyond a few single health care organizations engaged in electronic capture and exchange of device data. The Think Tank resulted in what has become two sustainable multi-stakeholder device data capture initiatives, BUILD and VANGUARD. These initiatives continue to mature within the MDEpiNet PPP structure and are well aligned with the goals outlined in recent FDA-initiated National Medical Device Planning Board and Medical Device Registry Task Force white papers as well as the vision for the National Evaluation System for health Technology.%.

Early fatigue fractures in the IS-1 connector leg of a small-diameter ICD lead: Value of returned product analysis for improving device safety

Conductor fractures may affect the performance of implantable cardioverter-defibrillator leads. During routine surveillance of returned product analyses (RPAs) in the Food and Drug Administration's Manufacturers and User Facility Device Experience database, we found a number of conductor fractures in small diameter implantable cardioverter-defibrillator leads manufactured by St Jude Medical, Inc (SJM, Sylmar, CA). To determine the location and cause of these fractures and to catalog their clinical signs and consequences. We searched the FDA's Manufacturers and User Facility Device Experience database on April 11, 2013. SJM provided information and data it collected independently. Our search found 59 leads with fractures in the IS-1 leg. Most fractures were in leads implanted in 2008-2009; no fractures were found in leads implanted after 2010. Outer coil conductor fractures accounted for the majority (51 of 59, 86%). Oversensing and noise were common signs, and 81% of the patients received inappropriate shocks. SJM's RPAs found that the fractures were due to inadequate strain relief and redesigned the IS-1 leg by shortening the crimp bore. Younger age and subpectoral implants appeared to be associated with these fractures. SJM stated the incidence is low (0.040%) and has not seen further fractures of this type in leads with the modified crimp. SJM's small diameter leads that were manufactured before 2011 are prone to early outer coil fatigue fractures in the IS-1 leg. The failure mechanism appears to have been mitigated by a design change. RPA is important for improving device safety.

Prevalence and nature of adverse medical device events in hospitalized children

Our objective was to describe the prevalence and nature of adverse medical device events (AMDEs) in tertiary care children's hospitals. In our retrospective cohort study of patients at 44 children's hospitals in the Pediatric Health Information System (PHIS), we included all inpatient stays with an AMDE-related diagnosis from January 1, 2004 to December 31, 2011. We identified AMDEs by diagnoses that specified a device in their definition. We included events present on admission as well as those complicating hospital stays. We described the characteristics of these admissions and patients, and stratified analysis by device category and presence of a complex chronic condition. Of 4,115,755 admissions in the PHIS database during the study period, 136,465 (3.3%) had at least 1 AMDE. Vascular access and nervous system devices together represented 44.4% of pediatric AMDE admissions. The majority (75.5%) of AMDE admissions were of children with complex chronic conditions. The most common age group was patients aged 2 years or less at the time of their first AMDE-related admission. AMDEs occur commonly in a population cared for in tertiary children's hospitals. Research to more specifically delineate AMDEs and their predictors are next steps to understand and improve device safety in children.

Reaching Higher…10 Ways to Improve Device Safety

safety? Recently, Biomedical Instrumentation & Technology (BI&T) reached out to clinical, industry, and academic experts for their patient safety guidance. They recommended 10 specific strategies that together convey a singular message: Push the boundaries on multiple fronts. Medical technology professionals could go deeper and broader, and act more aggressively and creatively, to improve policies and practices, according to the experts. Their rationale: realities in 21stcentury healthcare and beyond call for a different mindset today. The same forces that have transformed other major industries over the past decade are making an impact in the medical technology field as well, including globalization, rapid and constant change, increasing complexity and collaboration, and pervasive use of information technology and communications. Against this backdrop, several broad themes run through the experts’ recommendations for improving device safety. • Think globally. The device industry is global in scope, which requires operating on a worldwide playing field, from setting standards to research and development, design and manufacturing to reporting incidents. But thinking globally goes beyond geography. It also means breaking down silos that exist in healthcare, industry, government, and education to address issues holistically. • Work across disciplines. The increasing complexity of devices and the people who use them requires more collaboration among professionals who bring a diversity of expertise and perspectives to the table. • Be proactive. A defensive crouch isn’t the best position from which to improve device safety. Preventing problems before they occur is more effective than fixing them once they do. Medical technology professionals are often uniquely situated Reaching

A New Drug-Eluting Stent on the Horizon

Manufacturers of drug-eluting stents (DES) strive to improve device safety and efficacy. Three DES are now available in the U.S., and even more are