A prosthetic heart valve adapted for post-implant expansion and having an inflow end and an outflow end, comprising: an upper wireform undulating around a central axis with three upstanding commissure posts extending in an outflow direction alternating with three arcuate inflow cusps, and a fabric covering around the entire upper wireform; a lower wireform undulating around the central axis with three truncated peaks extending in an outflow direction alternating with three arcuate inflow cusp sections, and a fabric covering around the entire lower wireform, the lower wireform being positioned axially below the upper wireform with the three truncated peaks being aligned under three upstanding commissure posts of the upper wireform, and wherein the truncated peaks have an axial height of between about 10-30% of the commissure posts; three flexible leaflets having outer arcuate cusp edges attached between the inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform and outer tabs that extend outward between the commissure posts of the upper wireform and the truncated peaks of the lower wireform and are secured to the fabric covering around the upper wireform, the flexible leaflets being configured to ensure one-way blood flow through the heart valve, and wherein the inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform together define an implant circumference having a first diameter, and wherein the upper and lower wireforms (26, 28) permit expansion of the heart valve from the first diameter to a second diameter no greater than 3 mm larger than the first diameter upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling, and wherein the lower wireform has a shallow undulating shape that flattens out and prevents expansion of the heart valve beyond the second diameter. an upper wireform undulating around a central axis with three upstanding commissure posts extending in an outflow direction alternating with three arcuate inflow cusps, and a fabric covering around the entire upper wireform; a lower wireform undulating around the central axis with three truncated peaks extending in an outflow direction alternating with three arcuate inflow cusp sections, and a fabric covering around the entire lower wireform, the lower wireform being positioned axially below the upper wireform with the three truncated peaks being aligned under three upstanding commissure posts of the upper wireform, and wherein the truncated peaks have an axial height of between about 10-30% of the commissure posts; three flexible leaflets having outer arcuate cusp edges attached between the inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform and outer tabs that extend outward between the commissure posts of the upper wireform and the truncated peaks of the lower wireform and are secured to the fabric covering around the upper wireform, the flexible leaflets being configured to ensure one-way blood flow through the heart valve, and wherein the inflow cusps of the upper wireform and the inflow cusp sections of the lower wireform together define an implant circumference having a first diameter, and wherein the upper and lower wireforms (26, 28) permit expansion of the heart valve from the first diameter to a second diameter no greater than 3 mm larger than the first diameter upon application of an outward dilatory force from within the heart valve substantially larger than forces associated with normal physiological cycling, and wherein the lower wireform has a shallow undulating shape that flattens out and prevents expansion of the heart valve beyond the second diameter.