STENT FEATURES TO AID WITH APPOSITION AND ALIGNMENT TO NATIVE ANATOMY MITIGATION OF PARAVALVULAR LEAK

A collapsible and expandable stent is described that is adapted to treat blood flow regurgitation in a mitral valve or a tricuspid valve of a heart by allowing downstream blood flow and preventing upstream blood flow. The stent comprises an outer section comprising a first stent cell pattern, and an inner valve support section extending radially upward into the outer section and comprising a second stent cell pattern. The inner valve support section supports prosthetic valve leaflets attached therein. The stent further comprises a transition section between the outer section and the inner valve support section comprising a third stent cell pattern that is different from the first stent cell pattern and the second stent cell pattern. The transition section turns radially inward to give rise to a radially upward extension of the inner valve support section within the outer section. The transition section further comprises a plurality of curvilinear struts comprising a degree of curvature and/or twist. A spacing between adjacent curvilinear struts defines the third stent cell pattern of the transition section. Adjacent curvilinear struts are configured to nest together when the stent is collapsed.