A prosthetic heart valve for replacing a native valve includes a collapsible and expandable stent having a proximal end and a distal end, and a valve assembly including a plurality of leaflets, the valve assembly being disposed within the stent. The heart valve further includes a plurality of elongated legs each with a first end coupled to the stent and a free end, the elongated legs being configured to transition from an extended configuration to a relaxed configuration. A sealing portion connected to the plurality of legs forms a sealing structure when the legs transition to the relaxed configuration to reduce perivalvular leakage between the implanted valve and surrounding tissue.