A catheter device for implanting a papillary anchor into the heart to attach an artificial chordae line to the heart, the catheter device comprising: a housing section extending from a distal end of the catheter device along the length of the catheter device toward the proximal end of the catheter device, the housing section comprising a distal part at the distal end of the catheter device and a proximal part located on the proximal side of the distal part; an anchor deployment mechanism at the distal part of the housing section for deployment of the papillary anchor for attachment of the papillary anchor to the papillary muscle, wherein the anchor deployment mechanism is arranged for deployment of the papillary anchor from a stowed position of the papillary anchor by moving it outward in the distal direction relative to the distal part; the papillary anchor, which is held in its stowed position by the anchor deployment mechanism in the distal part prior to deployment, wherein the papillary anchor is for implantation in the papillary muscle to hold the artificial chordae line, the papillary anchor comprising a number of hooks for engagement with the body tissue and having a folded position and an unfolded position, wherein the papillary anchor is made of an elastic material such that the hooks can be elastically deformed into the folded position by application of a constraining force, and will return to the unfolded position when no constraining force is applied, and wherein the hooks are held in the folded position whilst the papillary anchor is in the stowed position within the distal part; characterised in that: the distal part of the housing has a non-circular shape for engagement with a corresponding non-circular form of the papillary anchor and/or the anchor deployment mechanism, such that when the papillary anchor is held in the distal part movement of the papillary anchor is restrained with respect to rotation of the papillary anchor about a longitudinal axis of the distal part due to engagement between the non-circular shape and the non-circular form. a housing section extending from a distal end of the catheter device along the length of the catheter device toward the proximal end of the catheter device, the housing section comprising a distal part at the distal end of the catheter device and a proximal part located on the proximal side of the distal part; an anchor deployment mechanism at the distal part of the housing section for deployment of the papillary anchor for attachment of the papillary anchor to the papillary muscle, wherein the anchor deployment mechanism is arranged for deployment of the papillary anchor from a stowed position of the papillary anchor by moving it outward in the distal direction relative to the distal part; the papillary anchor, which is held in its stowed position by the anchor deployment mechanism in the distal part prior to deployment, wherein the papillary anchor is for implantation in the papillary muscle to hold the artificial chordae line, the papillary anchor comprising a number of hooks for engagement with the body tissue and having a folded position and an unfolded position, wherein the papillary anchor is made of an elastic material such that the hooks can be elastically deformed into the folded position by application of a constraining force, and will return to the unfolded position when no constraining force is applied, and wherein the hooks are held in the folded position whilst the papillary anchor is in the stowed position within the distal part; characterised in that: the distal part of the housing has a non-circular shape for engagement with a corresponding non-circular form of the papillary anchor and/or the anchor deployment mechanism, such that when the papillary anchor is held in the distal part movement of the papillary anchor is restrained with respect to rotation of the papillary anchor about a longitudinal axis of the distal part due to engagement between the non-circular shape and the non-circular form.