A device for deploying a cardiac valve prosthesis (V) includes at least one constraint member (700, 800) for radially constraining radially expandable annular portions (V1, V2) of the valve (V). The constraint member (700, 800) is actuatable to release the annular portions (V1, V2) constrained thereby and permit radial expansion of these annular portions (V1, V2). The constraint member (700, 800) has associated a first, slow-acting actuating mechanism (3, 30, 40) and a second, fast-acting mechanism (2, 50), adapted to produce relatively slow and fast release of the annular portions (V1, V2) constrained thereby. The device may include a first constraint member (800) and second constraint member (700) in the form of telescoping sleeves. The slow-acting actuating mechanism (3, 30, 40) will thus act on the outer sleeve (4, 8, 800), while the fast-acting mechanism (2, 50) will act on the inner sleeve (5, 7, 700) to produce, respectively, slow and fast release of the annular portions (V1, V2).
