Abstract: A patient programmer for facilitating patient control over an implanted medical device, such as an implanted spinal cord stimulator or the like, is disclosed. A programmer in accordance with the present invention is a portable, light-weight, easy to use patient programmer. The programmer enables a patient to control the operation of his or her implanted device outside of a clinical setting. The programmer incorporates features which ensure that users of varying ages, education levels, dexterity levels, physical and mental health will be able to safely control the operation of their implanted devices, within predefined limits established by a physician or clinician. Circuitry is provided for avoiding battery depletion and/or undesired programmer/implanted device communication in the event that the programmer's key is accidentally depressed (for example, due to being jammed into a purse or pocket) or is depressed repeatedly or continuously over an extended period of time.

Abstract: Electrical tissue stimulator and method for limiting the programmability of stimulation pulse parameters. The tissue stimulator includes a plurality of electrodes and a memory for holding a stimulation pulse parameter limit value and a programmed parameter value of a stimulation pulse. A pulse generator applies electrical stimulation pulses to the electrodes in accordance with the programmed parameter value. Programming means is included for receiving remotely generated programming signals and altering the contents of the memory in accordance with the signals. Means is included for comparing the stimulation pulse parameter limit value and the programmed parameter value and for preventing an alteration of the programmed parameter value, unless it is within stimulation pulse parameter limits. The stimulation pulse parameters may include pulse amplitude, pulse width, and pulse rate and the programmed parameter limit values may be upper and lower limits.

Abstract: A fixture for testing a circumferentially compliant bioprosthetic valve. The fixture comprises a silicone rubber simulated aorta which approximates the geometry of a healthy human aorta and a cradle for the aorta. The compliance characteristics of the aorta can be selected by varying the proportions of ingredients in the silicone rubber, so that simulated aortas of different compliance but identical geometries can be provided. The compliant valve is disposed inside the aorta and held in place by suturing or the like. In one embodiment, the aorta and valve are supported by means of a cylindrical cradle, with the inflow and outflow ends of the aorta being folded over cylindrical rims on the respective inflow and outflow ends of the cradle. End caps are then fitted in place over the folded-over ends of the aorta, the end caps having holes therein to allow flow through the aorta and valve.

Abstract: A medical connector and method of using the connector to connect separate sections of medical tubing, especially tubing which is to be implanted in the human body. The connector includes generally cylindrical first and second end portions, the diameter of which are smaller than an enlarged middle portion. The end portions are sized to fit within the lumens of the tubing sections. The connection is made by grasping the enlarged middle portion and slipping each end portion into a respective tubing section until the tubing sections abut tubing stop surfaces located at each end of the enlarged middle portion. The enlarged middle portion makes the connector easy to handle and the tubing stop sections provide for accurate alignment of the connector between the tubing sections.

Abstract: A lead having a capture member for releasably engaging the enlarged distal tip of a stylet. The capture member is connected to the flexible tubular casing of the lead near the distal end and includes an aperture having a necked down portion and a socket portion. The socket portion is shaped to accommodate the enlarged distal tip of the stylet. As the stylet is advanced towards the distal end of the lead the enlarged tip enters the necked down portion and is directed towards the socket portion until it pops into and is engaged within the socket portion. Once engaged the lead can be advanced, partially withdrawn, or turned by manipulating the stylet handle.

Abstract: A connector for establishing an external connection with multiple-conductor implantable leads. The connector body is generally cylindrical in shape and includes a unique twist lock design. The cylindrical connector body has two sections which rotate axially with respect to one another, from an `open` position to a `closed` position. Each of the sections has a longitudinal slot therein extending along its surface parallel to the cylindrical axis of the connector. In the `open` position, the slots in the respective sections are in alignment, forming a single longitudinal opening. The opening is keyed to accept an elongated end piece from a lead stylet, the end piece being attached to the end of the implantable electrode. The end piece supports the end of the lead such that the multiple, spaced apart electrical contacts disposed on the lead are exposed on at least one side.

Abstract: A catheter with a retractable anchor mechanism for providing drugs and/or electrical stimulation to the human body. The catheter has a flexible tubular casing consisting of a outer member and an inner member which enclose at least one lumen. The retractable anchor mechanism is located near the distal end of the catheter and is moveable from a first extended position to a second retracted position. A capture member is connected to the anchor mechanism. The capture member has a socket portion and a necked down portion for guiding the enlarged tip of a stylet into the socket portion for releasable engagement therewith. The anchor mechanism is moved from the first extended position to the second retracted position by inserting a stylet and applying pressure in the distal direction and is moved from the second retracted position to the first extended position by partially withdrawing the stylet thereby applying pressure in the proximal direction.

Abstract: A system for disabling an oximetric device when radiation-carrying channels are exposed to excess ambient radiation is disclosed. It includes a transmitter channel adjacent the sample to be measured, means for isolating the channel from the sample so that it does not carry radiation reflected from or transmitted through the sample, a detector for receiving the transmitted signal, if any, and means for disabling the output in response to the transmitted signal. Preferably, the transmitter channel runs parallel to other transmitter channels in the device, and is isolated from undue ambient light. The system preferably includes means for determining when the second transmitted signal exceeds background noise and the output is disabled when the second transmitted signal exceeds background noise.

Abstract: An apparatus and technique for electrical stimulation of the central or peripheral nervous system based upon changes in position of the patient. A position sensor may be chronically implanted in the patient. One preferred mode uses a mercury switch position sensor which indicates whether a patient is erect or supine. This position information is used by a chronically implanted pulse generator to vary the stimulation intensity. The intensity may be controlled by changes in pulse amplitude, pulse width, number of pulses per second, burst frequency, number of pulses per burst, electrode polarity, or any other convenient parameter which accomplishes the particular medical purpose within an application. The output of the chronically implanted pulse generator is applied to the spinal cord, peripheral nerves, and/or targets in the brain with leads and electrodes in a manner consistent with the given medical need.

Abstract: A system for disabling an oximetric device when radiation-carrying channels are exposed to excess ambient radiation is disclosed. It includes a transmitter channel adjacent the sample to be measured, means for isolating the channel from the sample so that it does not carry radiation reflected from or transmitted through the sample, a detector for receiving the transmitted signal, if any, and means for disabling the output in response to the transmitted signal. Preferably, the transmitter channel runs parallel to other transmitter channels in the device, and is isolated from undue ambient light. The system preferably includes means for determining when the second transmitted signal exceeds background noise and the output is disabled when the second transmitted signal exceeds background noise.

Abstract: An apparatus and method for limiting access to a septum in a body implanted device. The apparatus includes a screen member which covers the septum. The screen member has a plurality of openings which are sized such that needles larger than a predetermined size will not pass through the openings. Needles of a size less than the predetermined size of the openings will pass through and be provided access to the septum.

Abstract: An electromagnetic flow meter for measuring the flow of blood through a conduit. Flow rate is measured by applying an electromagnetic field around the conduit, with the moving electrolytic blood inducing a current that is sensed by electrodes. The flow meter includes a substantially "E"-shaped magnetic core structure as well as an "E"-shaped hinged cover piece for defining a complete flux loop. In the circuitry, a floating ground arrangement is provided for enhancing the stability and sensitivity of the meter and to ensure appropriate patient isolation. A strong magnetic field, covering the sensing region and with little flux leakage, is alternately switched in polarity. The magnetic coil driver circuit employs an arrangement of switches for facilitating very fast polarity reversal. A two-level current source in the coil current driver greatly enhances the meter's efficiency and power dissipation characteristics.

Abstract: A system for disabling an oximetric device when radiation-carrying channels are exposed to excess ambient radiation is disclosed. It includes a transmitter channel adjacent the sample to be measured, means for isolating the channel from the sample so that it does not carry radiation reflected from or transmitted through the sample, a detector for receiving the transmitted signal, if any, and means for disabling the output in response to the transmitted signal. Preferably, the transmitter channel runs parallel to other transmitter channels in the device, and is isolated from undue ambient light. The system preferably includes means for determining when the second transmitted signal exceeds background noise and the output is disabled when the second transmitted signal exceeds background noise.

Abstract: An improved method and apparatus for introducing a flexible member into the epidural space of the spinal column of a patient employing an introducer assembly for achieving access to the epidural space. The introducer assembly includes an epidural needle assembly, including an elongated needle having a side opening at its distal tip, a hub at its proximal tip and a lumen extending therebetween, and a stylet removable insertable within the lumen of said needle through said hub and having a beveled tip and a hub. The distal tip may be curved in the direction of the side opening when unrestrained by the stylet. The introducer assembly has a locking mechanism which preferably includes a lug extending from the side of the needle hub and an L-shaped cut-out in the side of the stylet hub for receiving the lug therein and allowing its rotation 90.degree. to effect a bayonette-style locking of the two hubs.

Abstract: An apparatus for verifying the proper placement of a medical instrument, such as a needle, with respect to an implantable medical device, such as a drug dispensing port or pump. The apparatus includes an internal circuit which is implantable within the body tissue, and an external circuit for communicating with the internal circuit. The internal circuit includes an electrically conductive plate for sensing proper contact between the medical instrument and the medical device. A resonant circuit is coupled between the plate and the body tissue, and has a predetermined resonance frequency, such that an electrical path is established through the resonant circuit, the plate, the body tissue and the medical instrument when the medical instrument is in proper contact with the medical device. The external circuit includes a transmitter circuit for sending signals either pulsed or continuous to the resonant circuit.