New Stent on the Block Features Novel Braided-Wire Design

At the Vascular InterVentional Advances (VIVA) 2012 Conference held in Las Vegas October 9-12, IDEV Technologies Inc. (Webster, TX) presented data on its Supera stent. Based on a novel braided-wire manufacturing technique, the new technology differs from standard tube-based stents by combining both strength and flexibility, according to the company.

The data presented at the conference were derived from a study of 264 patients, some with lesions with a mean length of 8 cm and others with de novo or restenotic lesions in the superficial femoral and proximal popliteal arteries measuring 40-140 mm in length. The trial achieved one-year vessel patency rates not previously achieved in a pivotal trial for any stent placed in the superficial femoral artery (SFA) or proximal popliteal artery, the company says.

Because the SFA and proximal popliteal arteries are exposed to significant mechanical stress as a result of the bending and rotation of the knee, stents used to treat these areas should offer a significant range of motion without interrupting the anatomical function of the arteries. The Supera stent's design and its combination of flexibility and radial strength may account for its ability to restore durable patency in the SFA or proximal popliteal artery, the company suggests.

Data from the trial will be utilized as the basis of an FDA premarket approval application that the company expects to file in the fourth quarter of 2012. In the following Q&A, Christopher Owens, IDEV's president and CEO, discusses his company's new method for designing and manufacturing stents to treat peripheral vascular disease.

MPMN: Please say a few words about your company and your unique stent design. How does this design differ from that of standard stents on the market?

Owens: IDEV is an emerging medical device company, and we're developing technologies that protect and restore anatomical function. The focus of our efforts is to redefine endovascular treatment paradigms using new technologies or new stent designs. The first product that we have developed for restoring anatomical function is a highly differentiated stent technology called Supera. A proprietary design, it is completely different from standard nitinol stents because it is designed with high radial strength to provide maximal blood flow to affected areas from the time of stent deployment while maintaining good flexibility and high kink and fracture resistance. This design represents a new class of stents, known as vascular mimetic stents (VMS).

Supera is designed from six wires that are woven around a mandrel to create a stent structure. This stent structure exhibits both strength and flexibility. Because of this feature, it has the ability to adapt to and mimic vessel anatomy. In contrast, nearly all other stents in the marketplace start from a stiff hollow tube. Those stents are laser cut from the tube, and the final design does not enable the device to exhibit a high level of both strength and flexibility. Thus, if you want more strength, you have to leave metal in, but you then lose flexibility. And if you want more flexibility, you have to take metal out, but you then lose strength.

As a result of their design, standard laser-cut tubular stents do not work fluidly with the human anatomy, and they may be prone to a variety of deficiencies, such as kinking and increased fracture rates. They also may produce an insufficient lumen, since they may not have sufficient radial strength. These characteristics can result in undesirable outcomes for patients.

MPMN: Could you describe the material and design of your stent?

Owens: The stent is made from nitinol, which does not differ from the material used to manufacture other stents. What is different about our stent is the design. Instead of using a tube, we start with six nitinol wires and braid them around a mandrel in a tubular design to form a closed-cell structure. Then, the device is shape-set at high temperatures and subjected to multiple proprietary heat-treating processes that permanently force the wire braid to conform to a certain geometry. Then, the stent is finished by removing the heavier nitinol oxide, leaving behind a uniform passivated titanium-rich oxide that exhibits excellent biocompatibility and corrosion resistance.

Thus, our technology is essentially a combination of a superelastic nitinol product and a unique, highly differentiated design.

MPMN: How does your stent design promote better blood flow than stents that begin from a tubular construction?

Owens: Improved blood flow is inherent in the radial strength of our stent, which is designed to maintain a maximum lumen. The greater the lumen diameter, the greater the blood flow. Our technology also resists crushing. In independent mechanical tests comparing our stent with a competitive standard nitinol tubular stent, ours had at least four times greater radial strength. It also had 360% greater crush resistance, significantly improved flexion characteristics, kink resistance, and higher fracture resistance.

Basically you put a stent in the artery to increase the blood flow in the area that is affected by disease states. The higher radial strength and all of the other properties allow the stent to maintain a very circular lumen. And because of the radial strength of our stent, it maintains a nicer lumen over time, which promotes improved blood flow.

The other part of our design that is important is that the design actually mimics the vessel into which it is inserted. This brand-new 'vascular mimetic stent' adapts to and restores anatomical function. Thus, it moves in a very fluidlike way in the vessel as a result of its shape-memory material and the more-flexible wire construction. Because of this design, it also has great longitudinal flexibility.

MPMN: What is the status of your stent technology in the United States at present?

Owens: Totaling $1.4 billion, today's peripheral vascular disease stent market is very large. It's one of the fastest-growing cardiovascular market segments. And the superficial femoral artery segment, which develops technologies for treating the arteries in the legs, is growing at approximately 15% per year. Driven by obesity, diabetes, an aging population, sedentary lifestyles, and also improved detection capabilities, the market will continue to grow.

Supera is already on the market in key European countries, including Germany and France, where it is indicated for palliative treatment of biliary strictures produced by malignant neoplasms and for peripheral vascular use following failed percutaneous transluminal angioplasty. In the United States, on the other hand, the technology has achieved FDA 510(k) clearance for use in patients that have a biliary duct obstruction. In these applications, the stent is implanted to hold the duct open to allow fluid to pass through and to help prevent tumor ingrowth.

At this time, we are finishing a premarket approval Investigational Device Exemption trial for an SFA indication to achieve approval in the United States. We will file our PMA submission to the FDA for the Supera stent in the fourth quarter of 2012. There is a growing and consistent body of evidence indicating that our stent may be providing greater resistance to fracture, greater durability, and superior outcomes over standard stents on the market today.