Abstract: An active fixation lead assembly including a dual-pitch screw mechanism and a free spinning mechanism, which provides an improved capability for firmly engaging a lead tip upon heart tissue while avoiding damage to the tissue due to overtorquing of the lead. The dual-pitch screw mechanism employs an extendable coupling screw, firmly attached to a helical fixation coil. The thread pitch of the extendable coupling screw is greater than the thread pitch of the helical fixation coil so that the coil portion will move through tissue faster per revolution than the coupling screw, thereby embracing the tissue more tightly against the lead and improving the electrical connection between the tissue and the electrode. Generally, the free spinning mechanism allows the fixation coil to rotate freely after the fixation coil has been fully extended.

Abstract: An active fixation lead assembly including a dual-pitch screw mechanism and a free spinning mechanism, which provides an improved capability for firmly engaging a lead tip upon heart tissue while avoiding damage to the tissue due to overtorquing of the lead. The dual-pitch screw mechanism employs an extendable coupling screw, firmly attached to a helical fixation coil. The thread pitch of the extendable coupling screw is greater than the thread pitch of the helical fixation coil so that the coil portion will move through tissue faster per revolution than the coupling screw, thereby embracing the tissue more tightly against the lead and improving the electrical connection between the tissue and the electrode. Generally, the free spinning mechanism allows the fixation coil to rotate freely after the fixation coil has been fully extended.

Abstract: The cardiac lead comprises a tubular body having a proximal end and a distal end, a coiled conductor within the tubular body defining a lumen therein and having a distal end and a proximal end, a tip electrode mounted at the distal end of the tubular body, and an elongate stiffener wire comprising an elongate member made of a wire having a preset shape, a distal end and a proximal end positioned within the tubular body. The stiffener wire includes an electrical insulative material covering the elongate member for the length thereof to prevent short circuiting of the coils of the coiled conductor which may come in contact with the elongate member. A sleeve is provided for connecting a portion of the distal end of the coiled conductor to the tip electrode and for fixing the distal end of the elongate member at the distal end of the tubular body.