A fixture for immobilizing an arm of a patient for insertion of a catheter for heart investigation and intervention. The fixture comprises a first portion (41) intended to be arranged at the upper arm (3), a second portion (42, 44, 45) intended to be arranged along the forearm and a third portion (43) intended to be arranged at the wrist with the wrist in an opened and twisted position. The second portion is divided into a first part (44) connected to the first portion (41) at an angle of about 150 degrees and a second part (45) connected to the third portion (43) at an angle of about 210 degrees. The first part (44) and the second part (45) are interconnected by a semi-bracelet (46) or a flexible strap (63). In this way, the first portion may be arranged at the inside of the elbow and the third portion may be arranged at the hand back at the opposite side of the arm. The fixture is attached to the arm via several flexible straps. The fixture is adapted to immobilize the arm and the wrist in a position adjacent the navel, in which the radial artery of the arm is conveniently available for catheterization.
