A valve prosthesis comprises a valve fixation device that comprises a plurality of struts that run in a direction substantially parallel to the longitudinal axis; a first circumferential row of cells coupled to the plurality of struts; and a second circumferential row of cells coupled to the plurality of struts. The valve fixation device is compressible to a compressed state for delivery to an implantation site, and expandable to an expanded state for deployment at the implantation site. The plurality of struts are substantially rigid such that the plurality of struts do not change dimensions between the compressed state and the expanded state. The valve prosthesis also comprises a valve comprising a plurality of leaflets and a plurality of commissures. The valve is coupled to the valve fixation device such that the plurality of commissures are radially aligned with respective struts of the plurality of struts.