It is, of course, a requirement for interventionalists to see exactly where catheters are going during their often-delicate surgical procedures — in other words, the catheters must be radiopaque (visible on X-ray). This is typically accomplished by using steel marker bands in the catheter tubing — although the steel shows up fine on X-ray, it creates an undesirable stiffness that even the best physicians can find frustrating.
To solve this problem, Teleflex Medical OEM developed a novel multilayer technology that uniformly embeds a tungsten layer in the catheter. Tungsten is radiopaque yet highly flexible in powder form. This allows the catheter to be seen easily under fluoroscopy, without the stiff metal marker bands that can limit flexibility — a perfect option for those procedures that require highly flexible and radiopaque catheters.
The biggest challenge with tungsten encapsulation or other radiopaque fillers is that they must be evenly distributed and not contribute to increased wall thickness or increased outer diameter beyond the agreed specification; the inner profile/inner lumen must also not be narrowed. It is essential that the extrusion process is precisely controlled so the tungsten powder is properly embedded in the correct concentration and dense enough to be visible under X-ray, without being “lumpy.”
Physicians, hospitals, and health-care systems seek out devices that increase patient outcomes and reduce hospital stays, ultimately reducing the cost of health care. This has created intense interest in antimicrobial coatings on medical devices and certain instruments to reduce the possibility of post-surgical infections.
Medical industry suppliers are now producing resins that are “doped” with antimicrobial agents that then become a permanent part of the final plastic product. Silver is a popular antimicrobial agent that is incorporated into medical products today — silver ions are highly effective in killing bacteria and do not damage human tissue. Antimicrobial resins have been engineered that can kill deadly micro-organisms such as MRSA, a dangerous bacteria that is often found in hospitals.
Antimicrobial agents do not typically affect the physical or chemical behavior of their host polymers or thermoset materials during the molding process. Antimicrobial agents are “carried” by another compound that is mixed with the resin prior to extrusion; the agent, carrier, and plastic selected depend on the usage of the product. A key step in the process is calculating the amount of agent needed; the plastic is formulated to release silver ions at a pre-determined rate over the expected life of the product.
Although device companies don’t necessarily know all about these new technologies and advanced materials, they fully expect their key suppliers and design, development, and production partners to be expert advisors on these topics.
The best way for a medical device company to assure performance, quality, speed to market, and the lowest possible costs is to involve a single-source vertically integrated extrusion/ catheter vendor at the very earliest stages of product design and development. This is where the companies exchange information and share their knowledge about the latest technologies, materials, and processes. It’s a little like seeing a physician — the best results happen when the device company opens up candidly to the vendor’s questions about expectations, concerns, product usage, deadlines, markets, costs, or other barriers. Acceptance by the medical device company of this upfront “value engineering” from the outsource partner is what often leads to beneficial design modifications that streamline design, reduce prototyping and extrusion/manufacturing charges, accelerate throughput, improve quality, and speed up time to market.