Cardiovascular Implantable Devices
Exponent’s multidisciplinary expertise provides superior technical and scientific support to assist our clients in addressing complex issues related to cardiovascular, neurovascular, and peripheral endovascular implantable medical device technology. We provide rapid, focused, market-sensitive solutions to solve a variety of challenges associated with device design, device performance, and interaction with their environment, using our competency in device performance test evaluation, implant retrieval analysis, finite-element analysis (FEA), computational fluid dynamics (CFD), corrosion and fatigue testing, materials characterization, particle analysis, and assessment of cardiovascular injuries. Our engineers and scientists have extensive expertise in the medical device product development process, risk management, including biomaterial selection and characterization, preclinical test method development and strategy, regulatory submissions, experimental and analytical performance evaluations using either custom test methods or standard tests defined by the International Organization for Standardization (ISO) and the American Society for Testing and Materials (ASTM), as well as manufacturability, regulatory, quality assurance, and post-market surveillance.
Cardiovascular Device Performance Evaluation
We perform mechanical and materials evaluation of cardiovascular implants and delivery instrumentation for clients with needs pertaining to third-party design reviews, or in vitro testing for CE or FDA regulatory submissions. Evaluations can also be conducted to assess novel cardiovascular implant performance characteristics, to answer specific questions related to materials (metal, polymers, and hybrids), and functionality (fracture, electronic circuit/component failure, coating integrity, tissue interaction, battery depletion, drug elution, fluid flow). The team project portfolio also includes evaluation, trouble shooting, and verification of catheter-based systems. We are knowledgeable on design constraints, requirements, common materials, failure modes, manufacturing methods, and custom anatomically relevant test-method development and validation. We also have extensive experience conducting biomechanical evaluations using cadaveric models and validated finite-element (FE) models.
Our experience with in vivo animal models also can provide insight into mechanisms of metal ion release, tissue interaction (histology, scanning electron microscopic evaluation [SEM]), and structural integrity of cardiovascular devices. Exponent’s scientists and engineers assist clients with materials selection, accelerated testing, adhesion characterization, and failure analysis of protective and functional coatings used for biocompatibility, passivation, and drug delivery in cardiovascular devices.
Implant Retrieval Analysis
We have established international retrieval programs to collect explanted devices, including pacemakers, implantable cardioverter defibrillators (ICD), and their leads, stents, IVC filters, heart valves, abdominal aortic aneurism (AAA) stent grafts, and embolization coils and plugs. As part of this program, we have developed custom-made implant retrieval kits and device-specific forms. Our international repository has provided us with the opportunity to examine retrieved cardiovascular implants for wear and degradation, failure mechanisms, corrosion, fracture, and deformation. We also have the expertise to assist our clients with evaluations of fluid and tissue surrounding the implant, including histology, trace metal, and particle analysis.
Cardiovascular Device Related Testing Capabilities
- Able to perform tests in accordance with ISO and ASTM standards and adaptable to accommodate special requirements
- Tests address metal ion release (metal leaching), pitting corrosion, crevice corrosion, galvanic corrosion, fretting corrosion, corrosion-fatigue
- Elemental analysis of materials and corrosion products
- Mechanical (Fatigue and Fracture) and Environmental Testing
- Life prediction and fitness-for-service determination based on design inputs
- Durability testing of coronary and peripheral stents
- Durability testing of tissue and mechanical surgical heart valves, and TAVI/TAVR heart valves and annuloplasty rings
- Durability testing of IVC filters, abdominal aortic aneurism (AAA) stent grafts, and embolization coils and plugs
- Environmentally controlled testing environments
- Standard ASTM/ISO tests, as well as custom test methods and fixtures
- Soft and calcified tissue testing applications
- Cadaveric Testing
- Established relationships with donor foundations
- Development of experimental protocols with institutional review board (IRB) approval
- Dissection and specimen preparation facilities on site
- Imaging Capabilities
- Optical light-stereo, confocal, epifluorescent, and scanning electron microscopy
- High-resolution imaging for bone, soft tissues, and implants
- Access to computed tomography (CT), magnetic resonance imaging (MRI), and dual energy x-ray absorptiometry (DEXA)
- Metallographic facilities for sectioning, mounting, polishing, and etching materials
- Optical metallography
- Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR)
Finite-Element and Computational Fluid Dynamics Modeling
Our group has extensive experience developing and using detailed, validated FE models of biological tissues and medical devices for evaluation of surgical procedures and specific cardiovascular applications. Specifically, we can incorporate the following:
- Subject-specific model geometry based on medical images (x-ray, CT, MRI, intravascular ultrasound [IVUS], microCT, optical microscopy, cryosections)
- Nonlinear, validated material models for polymers, superelastic (Nitinol), and other alloys
- State-of-the-art hyperelastic anisotropic tissue modeling capabilities
- Robust contact algorithms for device/device and device/tissue interactions
- Modeling interaction between solid structures (vessels, airways, devices) and fluids (air, blood)
- Simulation of device deployment
- Simulation of blood flow, hemolysis, and blood trauma
- Finite-element models of coronary and peripheral stents
- Finite-element models of tissue and mechanical heart valves
- Finite-element models of Transcatheter Aortic Valve Replacement (TAVR / TAVI).
Animation of Coronary Stent Deployment: /Coronary-Artery-Occlusion/
"Fourteen-Year Trends in Pacemaker Implantation in the United States," Presentation at Heart Rhythm 2009.