Merit Medical's Wrapsody: First Cell-Impermeable Covered Stent Receives FDA Approval for Hemodialysis Access
Recently, Merit Medical announced that its cell-impermeable covered stent—Wrapsody—has received FDA approval for market launch. This marks the first cell-impermeable covered stent approved by the FDA for treating vascular access stenosis or thrombosis in hemodialysis patients.It is reported that Merit Medical plans to officially launch the commercialization of the Wrapsody stent in the U.S. market next year, providing hemodialysis patients with safer and more effective treatment options.
Founded in 1987, Merit Medical has been dedicated to the research, development, and manufacturing of devices for cardiac and radiological interventional procedures. Its product portfolio spans multiple fields, including inflation devices and accessories, diagnostic and therapeutic catheters and guidewires, non-vascular stents, and thrombolysis catheters. The successful market launch of the Wrapsody cell-impermeable covered stent will further enrich Merit Medical’s product lineup.
Patency rate exceeds 82%, 30% higher than traditional methods
For patients with renal failure, hemodialysis is undoubtedly the most effective means of sustaining life. The prerequisite for hemodialysis is the establishment of an autogenous or artificial arteriovenous fistula/graft (AVF/AVG). However, due to various factors such as the need for three puncture sessions per week, hemodynamic changes resulting from the arterial-venous connection, and anastomotic hyperplasia, AVFs/AVGs are highly susceptible to complications including stenosis, thrombosis, and infection, which significantly shorten their service life. To prolong the lifespan of AVFs/AVGs, patients are often required to undergo frequent surgical interventions.
In the United States alone, up to 687,000 procedures are performed annually to maintain patency of patients’ dialysis access. Of these, more than 10% involve stent placement. Although stents can improve long-term patency to some extent, restenosis often recurs after a period of time.
To this end, Merit Medical collaborated with Dr. Bart Dolmatch of the Palo Alto Medical Foundation to successfully develop Wrapsody, a cell-impermeable covered stent.
Key data from the WRAPSODY WAVE pivotal trial showed that cumulative patency rates at 6 months were as high as 89.8% and 82.0% in patients with arteriovenous fistulas (AVF) and arteriovenous grafts (AVG), respectively, treated with Wrapsody. Meanwhile, primary patency rates for the entire access circuit at 6 months reached 72.6% and 68.8% in AVF and AVG patients, respectively (compared to a 6-month patency rate of only 50–71% for conventional stents).
This is attributed to the unique three-layer structural design of Wrapsody. The outermost layer utilizes standard ePTFE material, which allows for necessary tissue ingrowth and effectively prevents stent migration. The middle layer employs a cell-impermeable fluoropolymer that blocks the pathway for transmural cell migration through the graft covering, thereby eliminating the need for drug coatings. The innermost layer is made of spun PTFE material, which significantly reduces fibrin deposition and subsequent thrombosis, achieving this goal without the need for additional coatings, chemicals, or drugs.
Furthermore, the Wrapsody stent features an ingeniously designed tapered end. It employs lower radial force to better conform to healthy tissue, thereby reducing vascular injury and improving long-term patency. Meanwhile, the nitinol alloy design allows for up to 25% foreshortening, ensuring superior conformity with the vessel. The introduction of this stent undoubtedly provides a new option for hemodialysis treatment in patients with renal failure.
Covered Stents: Diversified and Innovative Development
According to the “Industry Market Analysis Report on Vascular Interventional Medical Devices,” the global market size for covered stents is estimated to reach USD 1.13 billion in 2023, and is expected to continue expanding at a compound annual growth rate (CAGR) of 4.1% from 2024 to 2030. The market is undergoing significant innovation, with researchers and innovative companies continuously introducing technological and design advancements that drive upgrades in the performance, durability, and therapeutic efficacy of covered stents.
For example, in terms of material innovation, polytetrafluoroethylene (PTFE) has emerged as a preferred choice in the field of covered stents. This material not only effectively prevents tissue ingrowth, significantly reducing the risk of restenosis, but also helps inhibit neointimal hyperplasia. The iCast covered stent system, under Getinge, is specifically designed for the treatment of iliac artery occlusive disease. It is understood that the iCast covered stent features stent struts made of 316L stainless steel and an expanded polytetrafluoroethylene (ePTFE) encapsulating membrane.
Moreover, 3D printing technology is transforming the manufacturing of personalized covered stents. This technology enables covered stents to precisely match patients’ unique anatomical structures, allowing for customized dimensions and mechanical properties, thereby significantly enhancing their performance and integration within the vascular system. The latest generation of covered stents further incorporates drug-eluting capabilities, enabling precise local delivery of antiproliferative drugs and further reducing the risk of restenosis.
Furthermore, as a specialized type of covered stent, cell-impermeable covered stents offer superior biocompatibility and antithrombotic properties, attracting significant investment from numerous innovative enterprises. The Solaris SX covered stent, developed by Solaris Endoangio, utilizes an electrospun cell-impermeable membrane to effectively prevent tissue ingrowth, thereby enhancing vascular access patency and reducing restenosis. This stent also features excellent radial strength, crush resistance, high flexibility, and precise deployability, making it widely applicable in the treatment of dialysis access and peripheral artery disease.