A medical device and method for facilitating selection of a shape and/or size of an annuloplasty implant for a patient are disclosed. The device comprises a catheter with a proximal end and a distal end, and an extension member at least partly arranged inside the catheter with an operator end and a measurement end. The measurement end is extendable relative from the distal end of the catheter for apposition with at least one commissure of a cardiac valve. The measurement end of the extension member comprises means for guiding the annuloplasty implant at at least one commissure.