Exponent’s multidisciplinary expertise provides superior technical and scientific support to assist our clients in addressing complex issues related to cardiovascular and pulmonary (CVNP) medical device technology and intellectual property. 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 modeling, corrosion and fatigue testing, embedded software and stored programmable logic development, tissue engineering and characterization, and assessment of cardiovascular and pulmonary injuries. Our engineers and scientists have extensive expertise in the medical device product development process, including biomaterial selection and characterization, preclinical test method development and strategy, 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.
CVNP Device Performance Evaluation
We perform mechanical and materials evaluation of CVNP implants and delivery instrumentation for clients with needs pertaining to patent evaluation/infringement issues, third-party design reviews, or in vitro testing for FDA regulatory submissions. Evaluations can also be conducted to assess novel CVNP implant performance characteristics, to answer specific questions related to materials (metal, polymers, and hybrids), biocontrol and biosignal software (failure analysis, reliability and testing, interaction with hardware), and functionality (fracture, electronic circuit/component failure, coating integrity, tissue interaction, battery depletion, drug elution). 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 microscopic evaluation [SEM] ), and structural integrity of CVNP 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 CVNP devices.
CVNP Implant Retrieval Analysis
We have established international retrieval programs to collect explanted devices, including pacemakers, implantable cardioverter defibrillators (ICD) and their leads, stents, filters, heart valves, orthopedic, spinal, and cosmetic devices. 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 CVNP 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.
CVNP Related Testing Capabilities
Corrosion
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
- Complete physiologic load range
- 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 CVNP 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)
- Biological fluid flow
- Drug delivery via convection/diffusion/aerosol
Additional Research ExperienceIn addition to the expertise described previously, our engineers and scientists have wide-ranging research knowledge and are extensively published in several specialized fields:
- Biologic tissue mechanics
- Acceptance criteria for medical device corrosion
- Electrosurgical equipment, electrostimulation, and electropathology
- Toxicity and biocompatibility of biomaterials
- Surface treatment effect on medical device corrosion
- Tissue, polymer, and trace-metal analysis
- Rheology and rheometry
- Powder design and characterization, and particle-size analysis and measurements
- Drug/device combination product design, development, optimization, testing, and characterization
- Drug delivery system development, optimization, testing, and characterization
- Injury to cardiovascular and pulmonary tissues
Animation of Coronary Stent Deployment: http://www.exponent.com/Coronary-Artery-Occlusion/
"Fourteen-Year Trends in Pacemaker Implantation in the United States," Presentation at Heart Rhythm 2009.