US Patent 8034103 Annuloplasty prosthesis with an auxetic structure

An annuloplasty prosthesis including an inner tubular member having a lateral wall and exhibiting auxetic behavior when subject to a tensile stress along the longitudinal axis of at least one of its portions. The auxetic behavior may be obtained by perforating the tubular member with apertures of desired shape, thus obtaining, for instance, re-entrant honeycomb cell structures or cell structures with two-dimensional chiral symmetry.