Extendable/retractable screw-in tip design with an improved thread/screw mechanism

摘要

An implantable endocardial lead for use with a cardiac stimulation device includes an electrically active housing including a tubular end region extending to a terminal rim at the distal end of the lead and an electrical conductor within the lead extending between proximal and distal ends. An active fixation electrode within and spaced from the electrically active housing includes an electrically active helix coaxial with the endocardial lead coupled to the distal end of the electrical conductor and movable between a retracted position fully within the housing and an extended position advanced beyond the terminal rim of the housing for effecting penetration into the myocardial tissue. A guide system located proximally of the active fixation electrode serves to rotate the electrically active helix about the longitudinal axis as the helix is moved between the retracted and extended positions.