A prosthetic apparatus comprising: a polymeric valve; and a tubular stent disposed about a longitudinal axis and extending from a proximal end to a distal end, the stent defining a tubular passage between the ends; wherein the tubular stent has a proximal portion, a distal portion, and a middle portion located between the proximal and distal portions; wherein the proximal and distal portions each comprise a mesh of support struts forming at least one ring of open elements disposed about the longitudinal axis; wherein the middle portion comprises: a plurality of elongated posts extending along a direction substantially parallel the longitudinal axis between the proximal and distal portions; a crown shaped mounting ring attached to the posts and configured to mount the polymeric valve within the tubular passage; and a plurality of open regions (104, 207) distal to the mounting ring that are free of elongated posts, support struts, or other structures; wherein: the apparatus further comprises: a tubular, polymeric sheath extending along the outer surface of the tubular stent from the proximal portion to the distal portion, but not substantially covering the open regions (104, 207) in the middle portion, wherein the sheath is heat-shrunk onto the stent, characterized in that the sheath is molded by disposing a heat shrink tube about the polymer material and the stent and applying heat to soften the polymer material and cause the heat shrink tube to shrink and apply force to mold the polymer material to cause the sheath to flow around and encapsulate at least a portion of the stent to form the sheath and the polymeric valve is formed by dip molding. a polymeric valve; and a tubular stent disposed about a longitudinal axis and extending from a proximal end to a distal end, the stent defining a tubular passage between the ends; wherein the tubular stent has a proximal portion, a distal portion, and a middle portion located between the proximal and distal portions; wherein the proximal and distal portions each comprise a mesh of support struts forming at least one ring of open elements disposed about the longitudinal axis; wherein the middle portion comprises: a plurality of elongated posts extending along a direction substantially parallel the longitudinal axis between the proximal and distal portions; a crown shaped mounting ring attached to the posts and configured to mount the polymeric valve within the tubular passage; and a plurality of open regions (104, 207) distal to the mounting ring that are free of elongated posts, support struts, or other structures; a plurality of elongated posts extending along a direction substantially parallel the longitudinal axis between the proximal and distal portions; a crown shaped mounting ring attached to the posts and configured to mount the polymeric valve within the tubular passage; and a plurality of open regions (104, 207) distal to the mounting ring that are free of elongated posts, support struts, or other structures; wherein: the apparatus further comprises: a tubular, polymeric sheath extending along the outer surface of the tubular stent from the proximal portion to the distal portion, but not substantially covering the open regions (104, 207) in the middle portion, wherein the sheath is heat-shrunk onto the stent, characterized in that the sheath is molded by disposing a heat shrink tube about the polymer material and the stent and applying heat to soften the polymer material and cause the heat shrink tube to shrink and apply force to mold the polymer material to cause the sheath to flow around and encapsulate at least a portion of the stent to form the sheath and the polymeric valve is formed by dip molding.