A device for reshaping a cardiac valve (26), which is elongate and has such dimensions as to be insertable into a cardiac vessel (24). The device has two states, in a first state (K) of which the device has a shape that is adaptable to the shape of the vessel (24), and to the second state (k′) of which the device is transferable from said first state (K). Further, the device comprises a fixing means (22,23;22a,23a) for fixing the ends of the device within the vessel (24), when the device is first positioned therein, a shape-changing member (20;20a) for transferring the device to the second state (K′) by reshaping it, and a delay means (21;21a) for delaying said reshaping until the fixing of the ends of the device has been reinforced by keeping said device in said first state (K) until the delay means (21;21a) is resorbed.