A fixture for immobilizing an arm of a patient for insertion of a catheter for coronary investigation and intervention has a fixture board for insertion under a mattress carrying a patient. The fixture board further has a link for attaching an arm holder to the fixture board. The arm holder is arranged adjacent an elbow of the patient and has an arm support and a belt for attaching the arm to the arm support. In addition, a wrist holder is attached to the arm holder for supporting the wrist. The wrist holder may be sterilized and disposable. An instrument table is connected to said fixture board via a link. The distance between the arm holder and the fixture board may be adjustable.