The expansibility of the STJ was reduced in the double-ring group compared with the single-ring group. In contrast, our group has previously shown that expansibility in the aortic annulus is preserved after implantation of a subvalvular annuloplasty ring of 11% [15], which is within the normal range of aortic annulus expansion [6, 11]. The reduced expansibility with an annuloplasty ring at the STJ compared with the aortic annulus could be that the deformational capacity of the Dacron ring is exceeded by the hyperdynamic aortic tissue at the STJ.