Tuesday, June 17, 2025
6/17/2025
Low Profile Transcatheter Aortic Valve Implant - ABSTRACT Transcatheter aortic valve replacement (TAVR) is gradually becoming an essential alternative to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis (AS) at high or prohibitive surgical risk. The published PARTNER 3 and EVOLUT LOW-RISK trials have recently demonstrated that TAVR can be considered in low-risk patients. However, the long-term durability of transcatheter prosthetic valves has become a major concern nowadays, especially for young patients with greater life expectancy. Although increased efficacy and safety of the current leading TAVR valves (e.g., Medtronic CoreValve and Edwards Sapien) have been reported lately, tissue valve dysfunction and failure remain the limiting factors for the long-term outcome of TAVR. Furthermore, the application of those TAVR valves is limited to certain patients due to the use of the relatively large delivery system (typically 14-16 Fr. Size). There is a substantial clinical desire for a lower-profile delivery system since it accommodates a greater population of patients with peripheral artery disease or small arteries and reduces the risk of vascular complications following transfemoral TAVR. It is well known that calcification plays a major role in the failure of bioprostheses and other tissue heart valve substitutes. Mechanical stress imposed on the leaflets contributes to the growth of calcium crystals and collagen fibers’ disruption, which induces thrombosis, calcification, and early valve failure. Therefore, a superior biomaterial with appropriate mechanical (low stress) and structural (thickness) properties may provide a solution for prolongation of transcatheter valve durability and size reduction of delivery system. Our group has previously verified that swine and bovine pulmonary visceral pleura (PVP) are highly elastic and much thinner (~1/3 of the thickness) than bovine pericardial tissue typically used for the current TAVR valves. The larger compliance and smaller thickness of PVP make it possible to become a more durable valve leaflet and to be delivered with a lower profile delivery system (<14 Fr.). Thus, we propose PVP as a potential disruptive biomaterial for constructing bioprosthetic heart valves. The objective of the SBIR Phase I proposal is to determine the feasibility of the bovine PVP to serve as the leaflets of TAVR in chronic animals. To accomplish this goal, we set the following two Specific Aims: 1) To create a transcatheter aortic valve (TAV) from PVP into a smaller delivery profile (12 Fr.), and 2) To assess chronic in vivo performance of PVP TAVR in juvenile sheep for up to 24 weeks. We have calculated and tested that bovine PVP leaflets with thickness ≤ 0.1 mm can be crimped in a 12 Fr. catheter without causing tissue damage. The juvenile sheep model is the gold standard animal model for prosthetic valve testing. Completion of this study may provide a new type of bioprosthetic material for transcatheter heart valves that have potential to enhance the valve durability and improve TAVR outcomes. The success of this program would also deliver significant benefits to patients ranging from adolescents to the elderly with the limited size of the access arteries.
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