Absorbable Metal Stents Research Articles

Biocompatibility and performance testing of absorbable metal stents in vitro and in vivo

Aims: Metallic implants are the most applied treatment options in angioplastic interventions. Here we report important in vitro and in vivo characteristics of our newly developed absorbable metal stent (AMS) in comparison to the clinically applied steel stent 316L.

Bioabsorbable Stenting for Peripheral Arterial Occlusive Disease

Bioabsorbable stents offer an unproven but theoretically appealing means to address the deficiencies of current stent designs. Ideally, these stents would provide early postprocedural scaffolding support yet undergo a predictable process of reabsorption, thus removing the persistent stimulus for neointimal hyperplasia. Prototypes include polymeric formulations and magnesium-based absorbable metal stents. Current and future human trials will ascertain if bioabsorbable stents truly deliver a physiologic advantage in the treatment of peripheral occlusive disease.

Mechanical Properties of a Biodegradable Balloon-expandable Stent From Poly(L-lactide) for Peripheral Vascular Applications

Background: Biodegradable polymeric stents represent a competitive approach to permanent and absorbable metallic stents for vascular applications. Despite major challenges resulting from the mechanical properties of polymeric biomaterials, these stent concepts gain their attraction from their intrinsic potential for controlled biodegradation and facile drug incorporation. This study demonstrates the mechanical properties of a novel balloon-expandable slotted tube stent from PLLA. Method of Approach: Polymeric balloon-expandable slotted tube stents (nominal dimensions: 6.0×25mm) were manufactured by laser machining of solution cast tubes (I.D.=2.8mm, d=270±20μm) from biodegradable (1) PLLA and (2) PLLA/PCL/TEC. The stents were tested in vitro for their mechanical properties: deployment, recoil, shortening, collapse, and creep behavior under a static load of 100mmHg. In vitro degradation was performed in Sørensen buffer solution at 37°C. After 0∕2∕4∕8∕12∕24 weeks the remaining collapse stability and molecular weight were assessed. Results: All stents could be deployed by balloon inflation to 8bar at 1bar∕min (PLLA) and 3bar∕min (PLLA/PCL/TEC). Recoil, shortening, and collapse pressure were: 2.4%∕3.4%∕0.67bar (PLLA), and 8.8%∕2.3%∕0.23bar (PLLA/PCL/TEC). A static load of 100mmHg induced pronounced creep processes in the PLLA/PCL/TEC stent. The PLLA stent remained patent and exhibited no creep propensity. During in vitro degradation an increase in collapse pressure was observed (maxima at 12w: 1.3bar (PLLA), 0.7bar (PLLA/PCL/TEC)). At 24 weeks, molecular weight was decreased by 28% (PLLA), and 52% (PLLA/PCL/TEC). Conclusions: Stents fabricated from pure PLLA exhibited adequate mechanical properties. The slow permissible deployment rate, however, limits their potential application range and demands further development.

Preliminary Results After Application of Absorbable Metal Stents in Patients With Critical Limb Ischemia

To report the preliminary 3-month follow-up of a recently developed absorbable metal stent (AMS) for treatment of infrapopliteal lesions in patients with critical limb ischemia (CLI). Between December 2003 and January 2004, 20 patients (10 men; mean age 76 years, range 59-96) with symptomatic critical limb ischemia (CLI) due to high-grade (80% to 100%) infrapopliteal stenoses received 1 or 2 AMS devices for suboptimal angioplasty. Clinical examination and color-flow duplex imaging were performed in all patients at discharge and at 1 and 3 months. Angiographic procedural success was achieved in all 20 patients. One patient died (non-procedure-related) during the periprocedural period. Three months after the procedure, primary clinical patency was 89.5% (17/19). No major or minor amputation was necessary in any of the patients, yielding a limb salvage rate of 100%. The average improvement in Rutherford class was 2.3 at the 3-month assessment. A comparison of postprocedural and 1-month color-flow duplex ultrasound and magnetic resonance images clearly indicated the ongoing absorption process of the AMS. After 3 months, the primary clinical patency and limb salvage rates suggest a potentially promising performance of these AMS devices in the treatment of below-knee lesions in CLI patients.