A catheter device (1) is disclosed for transvascular delivery of a medical device to a cardiac valve region of a patient. The catheter device comprises an elongate sheath (2) with releasable locking members for controllably locking the elongate sheath in a shape at least partly along its length from a relaxed state to a locked state when positioned in relation to a cardiac valve. In one embodiment the device comprises an elongate member (4) with a distal end portion (9) comprising a plurality of expandable units (5). The elongate member is retractably insertable into the lumen of the elongate sheath.
