An implantable medical system comprising: an intravascular device comprising an electronic controller, a hermetically sealed housing containing the controller, a pacing electrode electrically coupled to the controller and mounted in proximity to a distal end of the housing, and a fixation member mounted to the distal end of the housing, the fixation member comprising a plurality of fingers spaced apart from one another around a perimeter of the distal end of the housing, and each finger comprising: a first segment extending from a fixed end of the corresponding finger and being elastically deformable between a relaxed condition and an extended condition, and between the relaxed condition and a compressed condition, and each first segment including a peripheral portion and a central cut-out portion, the peripheral portion framing the central cut-out portion and having an inside edge spaced apart from an outside edge of the central cut-out portion, and the central cut-out portion extending from a fixed end thereof to a free tip thereof, the fixed end of the central cut-out portion being integral with the peripheral portion in proximity to the fixed end of the corresponding finger, and the central cut-out portion being configured to prevent penetration thereof within tissue at the implant site; and a second segment extending from the corresponding first segment to a free end of the corresponding finger, the second segment being configured to prevent penetration thereof within tissue at an implant site, the second segment extending from the corresponding first segment in a proximal direction and outward from the device housing, when the first segment is in the relaxed condition, and the second segment extending distally from the distal end of the device housing, when the first segment is in the extended condition an intravascular device comprising an electronic controller, a hermetically sealed housing containing the controller, a pacing electrode electrically coupled to the controller and mounted in proximity to a distal end of the housing, and a fixation member mounted to the distal end of the housing, the fixation member comprising a plurality of fingers spaced apart from one another around a perimeter of the distal end of the housing, and each finger comprising: a first segment extending from a fixed end of the corresponding finger and being elastically deformable between a relaxed condition and an extended condition, and between the relaxed condition and a compressed condition, and each first segment including a peripheral portion and a central cut-out portion, the peripheral portion framing the central cut-out portion and having an inside edge spaced apart from an outside edge of the central cut-out portion, and the central cut-out portion extending from a fixed end thereof to a free tip thereof, the fixed end of the central cut-out portion being integral with the peripheral portion in proximity to the fixed end of the corresponding finger, and the central cut-out portion being configured to prevent penetration thereof within tissue at the implant site; and a second segment extending from the corresponding first segment to a free end of the corresponding finger, the second segment being configured to prevent penetration thereof within tissue at an implant site, the second segment extending from the corresponding first segment in a proximal direction and outward from the device housing, when the first segment is in the relaxed condition, and the second segment extending distally from the distal end of the device housing, when the first segment is in the extended condition a first segment extending from a fixed end of the corresponding finger and being elastically deformable between a relaxed condition and an extended condition, and between the relaxed condition and a compressed condition, and each first segment including a peripheral portion and a central cut-out portion, the peripheral portion framing the central cut-out portion and having an inside edge spaced apart from an outside edge of the central cut-out portion, and the central cut-out portion extending from a fixed end thereof to a free tip thereof, the fixed end of the central cut-out portion being integral with the peripheral portion in proximity to the fixed end of the corresponding finger, and the central cut-out portion being configured to prevent penetration thereof within tissue at the implant site; and a second segment extending from the corresponding first segment to a free end of the corresponding finger, the second segment being configured to prevent penetration thereof within tissue at an implant site, the second segment extending from the corresponding first segment in a proximal direction and outward from the device housing, when the first segment is in the relaxed condition, and the second segment extending distally from the distal end of the device housing, when the first segment is in the extended condition