Abstract: An implantable medical device for optically sensing action potential signals in excitable body tissue. The device includes an elongated tubular lead body carrying an optical fiber extending from a proximal lead end to a distal lead end to position the optical fiber at a target site. The lead body additionally carries a conduit for dispensing a voltage-sensitive fluorescent dye into tissue surrounding the target site. The optical fiber transmits excitation light to the fluorescent dye to cause the dye to fluoresce with varying intensity as the transmembrane potentials of local tissue cells vary due to passing depolarization wavefronts. The optical fiber transmits the fluorescence signal to the device to generate an action potential signal or fiducial points of an action potential signal for use in accurately measuring and characterizing electrical activity of excitable tissue.

Abstract: A non-sheath based medical device delivery system is provided including an elongated tubular guide body having a distal end fixedly attached to a resilient collet with a longitudinal opening to receive a medical lead or other device. The collet may be opened by actuating a retraction member to cause the closing member to slide proximally along the collet shaft, allowing the collet to maintain a normally open position. With the collet closed, the device may be advanced to a desired internal body location by advancing the guide body. The majority of the device body will be exposed, running alongside the guide body, allowing any sensors or electrodes located on the device body to be fully operational during the implantation procedure. The delivery system may be removed by opening the collet, to slidably disengage from the device body.