A multi-leaflet valve, which includes at least two leaflets, an outer tube, and a seam protector for each seam. Each seam protector is positioned to be in contact with a portion of the outer tube, with tube portions and leaflet ends being positioned between adjacent seam protection pieces. The seam protectors provide a lower stress surface about which the leaflets can bend or flex during their opening and closing. The seam protectors may include an enlarged end portion with an extending straight surface, an inverted U-shaped structure, or a sinusoidal-shaped structure, for example. The valve can further be provided with a seam cover or protector that is stitched onto the seam allowance of the layers of one or more of the seams. The seams can be provided with one or more inserts to fill spaces between adjacent tissue layers and create tension in certain material sheets.