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Bioabsorbable Stents for Pediatric Pulmonary Artery Stenosis and Aortic Coarctation


Summary Mechanical stents to relieve obstructive cardiovascular lesions could have great utility in pediatric cardiology, but are unsuitable for small children. Commercially available stents limit vessel growth and require future surgical removal. Absorbable stents might revolutionize the treatment of congenital heart disease in children. Small children require small delivery systems for devices that are larger than adult coronary arteries. Specific target diseases include aortic coarctation and pulmonic stenosis, which currently require open surgical repair or multiple X-ray-guided catheter procedures in early childhood. Project Goals These are transcatheter stents to be delivered using conventional interventional cardiovascular techniques including guiding catheters or sheaths, translesional guidewires, and balloon-expandable or self-expanding delivery systems. Conventional and novel approaches are welcomed. Specific requirements of the stents include small delivery systems (5-6 French or smaller); sufficient radial force to resist elastic recoil for the two applications; sustained radial strength suited to the application for at least 6 months; controlled degradation within 6-12 months; inflammatory response that does not cause significant stenosis, restenosis, or aneurysm; resistance to downstream embolization or toxicity; and nominal calibers suitable for the most common lesions (pulmonary artery stenosis and aortic coarctation, see below) . Proposed stent nominal geometry should be diameter (6-10mm), length (range 10-25mm), delivery system (5-6 French or smaller). The radial hoop strength of the deployed device should approach that of commercial balloon-expandable stent such as the Cordis Palmaz Genesis. Percutaneous vascular access routes for the pulmonary artery application include femoral and jugular venous. Percutaneous vascular access routes for aortic coarctation application include transvenous-transeptal antegrade and retrograde transfemoral artery. The implant or the delivery system should be conspicuous under the intended image-guidance modality. Offerings should specifically provide the high radial force required to overcome immediate recoil of the intended applications, and should allow “direct stent” treatment technique for native and iatrogenic lesions. Phase I Activities and Expected Deliverables Phase I should focus on mechanical and biological performance of the proposed biodegradable stents in the intended use for pulmonary artery stenosis and aortic coarctation, taking into account mechanical strength required for the application; geometry of the access vessels and geometry and morphology of target vessels including tapering and branching; strategies to avoid inflammatory restenosis or constriction; and delivery, implantation, and visualization strategies. At the conclusion of phase I, a candidate device design should be selected for clinical development based on in vivo performance of a mature prototype resembling a final design. The sponsoring NHLBI laboratory is willing to perform a limited number in vivo proof-of-principal experiments in swine (by mutual agreement) to confirm mechanical performance. Phase II Activities and Expected Deliverables At the conclusion of phase II, the offeror should obtain an investigational device exemption (IDE), and a supply of devices provided, for a first-in-human research protocol, involving at least 10 subjects, to be performed by the sponsoring NHLBI laboratory. The sponsoring NHLBI laboratory is willing to perform a limited number of in vivo proof-of-principal experiments in swine (by mutual agreement). NHLBI offers to perform the clinical trial at no expense to the offeror, to participate in the development of the clinical protocol, and to provide clinical research services. The vendor is expected to perform or obtain safety-related in vivo experiments and data to support the IDE. The specific Phase II deliverables are as described under Phase I. • The phase II award would consist of the contractor obtaining an IDE based on the design finalized in phase I.
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