30 Jun Biomedical Textile Design for Cardiovascular and Endovascular Applications
By John Greco, Vice President, Sales
Biomedical textiles have been incorporated in to medical devices for cardiovascular and endovascular applications for more than 50 years. Initially, textiles were limited primarily to vascular grafts and heart valve sewing cuffs for use in traditional aortic valve repair. This eventually expanded to include products for repairs of the iliac artery and, later, textiles have proved to be viable options for use in thoracic surgery. As textile structures have become more innovative, with complex and fully customizable geometries, implantable fabrics are no longer limited to traditional applications and can actually support and promote the healing and even the regeneration of damaged cardiovascular tissue. Today, textiles are used to create biocompatible heart valve fabric, aortic arch reinforcement, stent graft covering, carotid artery repair fabric, tissue grafts, and more.
Implantable textiles can be formed via knitting, braiding or weaving of medical-grade fibers. Based on the woven or non-woven process used and the biomaterials selected (for example, ultra-high molecular weight polyethylene, polyester, polypropylene etc.), the characteristics of the fabric can be tailored by design engineers to the specific needs of the surgical application. Textiles can also be used for composite products combining polymeric and metallic filaments, for example a stent graft composite (mixing wire with polyester).
The nearly limitless combination of patterns and advanced geometries that can be created by today’s engineers through a combination of material selection and software programming allows characteristics such as porosity, flexibility, thickness, and stability to be completely controlled. This has created exciting opportunities to use textiles unlike ever before.
Early stents used for endovascular applications were very large, but have evolved to be much smaller – thanks in large part to the improved robustness of biomedical textiles. Today’s textiles have the flexibility and shape transformation capabilities to be engineered for insertion through a smaller catheter and to expand within the vessels, allowing for minimally invasive delivery methods without sacrificing any mechanical integrity. This is particularly beneficial for patients with small vessels, and for repairs in the three branches of the aortic arch, which has long been challenging. Even in thoracic surgery, where pressures are significantly higher than in abdominal areas, textiles have proven very successful due to the development of high-performance medical grade yarns and dense fabric constructions. The goal continues to be to make smaller, lower profile devices to facilitate less invasive procedures.
The next area likely to see increasing growth and innovation is Transcatheter Aortic Valve Replacement (TAVR). With a typical heart valve replacement, a patient is put on a bypass machine while the surgeon works quickly to excise the old valve, put the new valve in, and suture the patient up while hoping for the best outcome. Already fragile patients, such as the elderly, struggle to survive the intense nature of a bypass, and survival rates amongst these populations are low. Textiles can be incorporated in TAVR products to prevent abrasion and encourage tissue growth. For example, a braided sleeve can go over a stent so, in a failure mode, the stent will rub against the textile material rather than the patient’s tissue. Additionally, textiles can help develop a thrombus on the surface so blood doesn’t pass through, playing an integral role in the clotting cascade.
Warp knitting, in particular, is ideal for creating textile products for vascular applications (especially for mitral heart valve replacement) because it can produce very thin, dense textile structures that prevent blood leakage around the valve. Porosity can be tailored to recruit the desired cell by size, creating specialized regions of tissue regeneration. Densities can be rapidly changed so you can transition from dense to porous within a single fabric. For cardiovascular fabrics, this means blood leakage can be prevented inside the valve while native tissue ingrowth is encouraged outside. Knits are very compliant allowing the implant to stretch and move with the body, reducing patient discomfort and restoring natural mobility.
Cortland Biomedical has the expertise, capabilities and machinery to create textile designs unrivaled in their complexity, resulting in products that can be simultaneously low profile and mechanically robust. With state-of-the-art textile forming and post-processing capabilities, Cortland Biomedical’s engineers are fully equipped to partner with you in creating the most effective final product.
Contact us today to find out how Cortland Biomedical can work with you to develop innovative textile structures for your cardiovascular or endovascular medical device needs.