A prosthetic valve is provided that includes a tubular valve body and a plurality of prosthetic leaflets disposed within a lumen of the valve body. The valve body includes struts, has an upstream end and a downstream end, and defines a lumen. The valve body is shaped so as to define a circumferential row of four-sided closed cells. Each of the four-sided closed cells is defined by some of the struts, which are shaped so as to collectively define the following four sides: a left upstream side, a right upstream side, a left downstream side, and a right downstream side. Each of the four sides of each of the four-sided closed cells is double-strutted. Other embodiments are also described.