By Andrew Metzger, Sr. Director of Corporate Strategy, Solesis, parent company of Secant Group
Implantable medical textiles, originally used as sewing skirts for suturing valves in the heart during open-heart surgery, have been evolving since the industry transitioned from open surgical valves to minimally invasive transcatheter devices. The ubiquity of minimally invasive heart procedures such as transcatheter aortic valve replacement (TAVR) has helped to demonstrate the versatility of implantable medical textiles.
The medical device industry has demanded thinner textile materials to ensure that implantable devices can better accommodate minimally invasive heart procedures. As such, raw materials have become more versatile to include smaller, finer denier yarns and new, texturized materials. This flexibility enables fabrics to be modified in countless ways to enhance the functionality of cardiovascular devices.
To ensure a cardiovascular medical device includes the right materials, device designers can work with an expert textile partner to understand how different fabrics work, including the functional differences between braided, knit, and woven textiles. An expert partner who is solely dedicated to designing and manufacturing textiles — and who understands the applications of those devices — can help organizations leverage the benefits of each textile-forming technology, whether applied to a novel device or modifying or improving a predicate device.
Medical Textile Use in Cardiovascular Devices
In cardiovascular devices, textiles are used in three ways: 1) as flexible scaffolds for tissue in-growth and implant integration; 2) as conduits or barriers for blood flow; 3) and to join materials and secure implants in the body. Device makers often integrate different types of textile structures within a single device, functionalizing each textile to fit the device requirements to provide the prescribed benefits.
Three key textile-forming technologies exist to serve these applications: braiding, knitting, and weaving. Each has its own benefits:
- Braiding is used to make sutures, tubular coverings, wire stents, or stent frames. Braided textiles are ideal for covering complex structures on frames (e.g., tubes or dynamic shapes). They can be used for foreshortening and expansion, to prevent metal exposure, and/or to hold a valve in place against native tissue. Like all textiles, braided structures help provide tissue in-growth activities due to their fibrous nature. Accordingly, braided structures are used in many structural heart devices, including clipping and heart valve solutions, devices for replacement or repair, and bypass grafts.
- Knitting provides robust flexibility, smooth conformability, and potential for 3D porosity, making this textile-forming technology ideal for materials that need to stretch over or cover something (e.g., 3D device designs). They also have thermoforming capabilities. The porosity of knit materials is controllable, which aids tissue integration. Thicker than woven fabrics, knit fabrics can add loft to a surface and can be applied for integration, blood wicking, and sealing. Knit materials have traditionally been used in surgical open-heart valve procedures. In tubular configurations, they’re used in left atrial appendage occlusion (LAAO) devices, leaflet clipping products, and patent foramen ovale (PFO)/atrial septal defect devices.
- Weaving creates thin, highly dense material that can be utilized to create complex, near-anatomical structures. The thinness of the material renders it packable within a catheter delivery system and, when unfurled, it retains the shape intended by the device manufacturer when built in conjunction with wire-frame forms—specifically nitinol, which has shape memory properties—and sutures. Thus, woven materials are not constrained to their original geometry when passing through a catheter for delivery to the heart, abdomen, or other locations within the body. Moreover, woven textiles exhibit high permeability resistance without the bulk or elasticity of knit or braided materials, making them ideal as blood conduits. Woven materials are considered the gold standard for heart valve skirts and AAA grafts.
Next-Gen Textile Creation and Use
While the base technology for creating braided, knit, or woven textiles hasn’t changed much over the years, the implantable medical device industry constantly pushes textile technology to be more efficient, automated, and precise to better serve next generation needs. Consider that, moving forward, composite or surface-modified structures could potentially address biological issues in the cardiovascular space such as thrombosis and durability in the following ways:
Composites
- Composite-based materials could replace biologics through biomimetic design capabilities.
Scaffolds and Tissue Engineering/Regeneration
- High-surface area nanofiber electrospinning can be used to make resorbable materials act as tissue scaffolds for endogenous tissue regeneration, potentially providing an improved nanofiber surface to facilitate tissue growth.
- Textiles can be used as scaffolding for tissue engineering or fully integrated heart valve structures.
Coatings
- Non-resorbable and resorbable polymers — including polyglycerol sebacate (PGS) and polyglycerol sebacate urethane (PGSU) leaflets, used in conjunction with textiles to optimize their mechanical properties — may represent the future of fully synthetic heart valve developments.
Conclusion
Demand for minimally invasive heart procedures has grown, especially as TAVR becomes an option for low-risk patient populations. This has directly impacted the need for device and material innovations. Issues associated with durability, thrombosis, and other biologically based complications must be considered when designing devices for these patient populations. Specifically, as these devices receive approval for lower-risk indications—especially in younger populations that expect to live longer post-op— device design durability must be addressed to avoid the need for additional TAVR procedures.
As medical devices evolve, medical textile technology must also evolve with industry demands. Therefore, new technologies and fabric modifications for skirts and frames, for example, should be developed to meet both well-understood and emerging needs in the cardiovascular device space.
Medical device manufacturers can meet those emerging needs and create new heart valve devices — and improve upon existing products — by leveraging the knowledge and expertise of a world-class textile designer. With an expert by their side from sketch to scale, device manufacturers can move quickly by using optimized raw materials that are chosen early in the design process, leveraging readily available fabric samples, and working closely with a team of textile engineers to guide the design and manufacture of custom fabrics for their next cardiovascular device innovation.
To learn more, contact the authors and visit us at https://secant.com.
About The Author
Andrew Metzger is Sr. Director of Corporate Strategy at Solesis. Andrew leads Solesis’ medical device component business strategy, developing long-term growth plans with a focus on solving unmet needs within cardiovascular, general surgery, neurovascular, and orthopedic markets. Andrew has a Bachelor of Science degree in biomedical engineering from Drexel University.
About Secant Group
Secant Group designs and develops custom-engineered, next-generation textiles and biomaterials solutions that enable repair, recovery, and regeneration of the human body.
With decades of experience in implantable medical component design, development, and manufacturing, Secant Group gives market leaders confidence to innovate more boldly across medical devices, cell therapy, tissue engineering, and drug delivery to make lifechanging breakthroughs more accessible to more patients with unmet needs.
From prototyping to commercialization, Secant Group is the collaborative, integrated partner of choice in the cardiovascular, neurovascular, orthopedic, surgical, and pharmaceutical spaces.
