Shape memory polymer foams to seal space around valves
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Publication Number
US-11219520-B2
Publication Date
2022-01-11
Expiration Date
Abstract
An embodiment includes individual SMP foams that radially expand and fill gaps around a heart valve that may be improperly seated, in an unusual cross section, or has poor apposition against a calcified lesion. Other embodiments are described herein.
Core Innovation
The invention relates to a stent that includes windows and a valve included within the stent, together with an open-cell polyurethane thermoset shape memory polymer foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus. The SMP foam substantially covers at least 80% of a first face of a selected window.
A key aspect is selective coupling of the SMP foam to only some of the stent struts. In a first orientation, the SMP foam is in the compressed secondary state and the fixedly coupled struts constrain the foam movement, while other struts do not fixedly couple to the SMP foam; in a second orientation, the SMP foam moves dependent upon the fixedly coupled struts and independent of the struts that do not fixedly couple.
The invention further specifies geometric and spatial constraints for foam behavior during orientation change, including first and second planes orthogonal to the long axis that intersect distinct sets of struts. In an additional configuration, a membrane contacts first and second struts, and an upper portion of the SMP foam is adhesively adhered to the membrane while a lower portion is not adhesively adhered and slides over the membrane as the apparatus transitions between orientations.
Claims Coverage
The document includes three independent claims. Across these claims, the coverage centers on a valve-in-stent apparatus using an open-cell polyurethane thermoset SMP foam that thermally expands between compressed and expanded states, selective fixed coupling of the foam to some struts while decoupling from others, and optional structural constraints via plane intersection rules and a membrane with an upper adhered and lower sliding foam portion.
Valve included within stent with open-cell polyurethane thermoset SMP foam expansion
A stent with windows and a valve included within the stent, and an open-cell polyurethane thermoset SMP foam configured to expand from a compressed secondary state to an expanded primary state in response to a thermal stimulus.
Substantially covering at least 80% of a window face
The SMP foam substantially covers at least 80% of a first face of a third window, the third window having a first face and a second face that oppose one another.
Selective fixed coupling of SMP foam to selected struts
The first and second struts fixedly couple to the SMP foam, while the third and fourth struts do not fixedly couple to the SMP foam, such that the SMP foam moves dependent upon the fixedly coupled struts and independent of the non-fixedly coupled struts during transition from a first orientation to a second orientation.
Orientation-dependent dimensions with compressed-to-expanded SMP state
A first orientation defines a first maximum stent outer diameter and associated third-window length and width while the SMP foam is in the compressed secondary state; a second orientation defines a second maximum stent outer diameter greater than the first and associated third-window length and width with length less and width greater while the SMP foam is in the expanded primary state.
Plane intersection constraints relative to coupled versus non-coupled struts
First and second planes orthogonal to the long axis intersect the SMP foam and different sets of struts, with the first plane not intersecting the third and fourth struts and the second plane not intersecting the first and second struts.
Membrane adhesion on upper foam portion with lower foam sliding
A membrane contacts the first and second struts, where a location within an upper half of the SMP foam directly adheres to the membrane via an adhesive that directly contacts both the membrane and the SMP foam, and a lower half does not directly adhere via any adhesive and is configured to slide over the membrane as the apparatus transitions between orientations.
Overall, the independent claims cover a valve-in-stent apparatus using an open-cell polyurethane thermoset SMP foam that thermally expands between compressed and expanded states, combined with selective fixed coupling of the foam to some struts and decoupling from others to control foam movement during orientation change. Additional limitations include orientation-dependent geometric relationships, plane intersection and avoidance constraints, and a membrane arrangement where an upper foam portion is adhesively adhered while a lower foam portion slides.
Stated Advantages
Documented Applications
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