Abstract: A processor fabricated in a semiconductor chip has on-chip program memory and access to off-chip program memory. Switching between the on-chip memory and the off-chip memory is effected in the course of program execution, without using a pin-out of the device package in which the processor is housed or encapsulated, by writing a system configuration bit stored in a memory location shared by the on-chip and off-chip memories to a "1" or a "0" according to whether the program instruction is to be executed from the on-chip memory or the off-chip memory.

Abstract: A semiconductor microcontroller includes the capability to perform analog to digital conversions of an analog signal representative of a variable parameter indicative of the need to exercise a control function. While the analog to digital conversions are being performed, the microcontroller processor can be powered down to eliminate noise arising from switching activities of the processor as a source of inaccuracy in the conversion process. At the end of the conversion, the analog to digital converter can either shut itself down or wake up the processor. The powering down is achieved by simply disabling the clock input to the microcontroller so that the processor is still activated but incapable of undergoing switching functions.

Abstract: An electrical lead has a cardioverting/defibrillating electrode composed of a multiplicity of tiny flexible elongate metallic fibers, for implantation in a patient. One embodiment of the lead is implanted by puncturing the chest/abdominal wall of the patient and inserting the lead, fiber electrode first, into the body through the puncture site followed by maneuvering the lead by endoscopy to position the electrode adjacent the epicardium of the heart for electrical interaction with the ventricles. The fibers may be interwoven to form a thin tube prestressed to assume a flat spiral shape to permit it to be straightened with a stiffening wire for maneuvering to return to its flat spiral shape after proper positioning and removal of the wire. In other embodiments, the lead has multiple conductors electrically connected to respective electrodes arranged on the lead for positioning transvenously relative to selected regions of the heart.

Abstract: An implantable medical interventional device for delivering electrical therapies to the heart of an implant patient to treat pathologic ventricular tachycardia. The device includes a first sensor for developing a signal indicative of the patient's ventricular ECG status, and a second sensor for developing a signal indicative of the patient's atrial ECG status. Criteria are established to distinguish physiologic tachycardia and pathologic tachycardia in the ventricles by an evaluation of the signal indicative of ventricular ECG status, and an appropriate is therapy is delivered if the evaluation indicates a pathologic tachycardia in progress. The therapy delivery is limited to an atrial response if the signal developed by the second sensor indicates atrial fibrillation or other atrial dysrhythmia, and is appropriate to that particular dysrhythmia.

Abstract: Power consumption of a serial EEPROM is reduced while simultaneously precluding data corruption during write operations. These results are achieved by operating a brownout detector in the device to sense EEPROM supply voltage below a predetermined level and thereupon to place the EEPROM in a reduced power mode, but only during an interval that a write sequence is taking place. Such an interval includes loading of data in a temporary storage cache and writing the loaded data into the EEPROM. At the same time that the low voltage level is detected during a write sequence, any load or write operation then in progress is aborted. The brownout detector is intentionally left disabled or in a sleep mode during any read mode or standby mode since there is no jeopardy of corrupting the EEPROM memory during those times.

Abstract: An implantable medical interventional device delivers electrical therapies to the heart of the implant patient to treat pathological tachycardia. A first sensor of the device generates a signal indicative of the patient's ECG, and a second sensor in the form of an activity sensor such as an accelerometer generates a signal representative of the current status of physical exercise by the patient. An evaluation system of the device establishes heart rate criteria for recognizing pathological tachycardias, to be applied against the ECG signal to recognize pathological tachycardia and distinguish it from physiological tachycardia experienced by the patient. A control system of the device modifies the criteria according to the nature of the exercise status signal, to enhance recognition and distinction. In an embodiment, the criteria of heart rate at the boundary between physiological and pathological tachycardia for the particular implant patient is modified by shifting it to a different rate.

Abstract: An erasable programmable memory device has a number of data storage blocks. Each block has an endurance characteristic that at least roughly defines the number of times data may be erased from and written to the block before it wears out in that data cannot then be further erased from and written to the block. A redundant data storage block of memory capacity and endurance similar to that of each of the other data storage blocks is disposed in parallel with a selected one of the latter for which higher endurance is desired. This enables identical data to be written simultaneously to the two blocks and thus considerably increases the endurance of the selected block by virtue of the fact that identical memory cells in both blocks must fail before the endurance of the selected block will be depleted. After the selected block has been designated for high endurance and placed in parallel with the redundant block, a fuse may be set to prevent alteration of that designation.

Abstract: A variable rate implantable pacemaker responsive to patient exercise senses and distinguishes between distinct and different types of physical activity by the patient, and is programmed to respond by generating different response functions to control the pacing rate according to the specific type of physical activity detected. The response functions are algorithms, taken from the behavior of a healthy person with normally functioning cardiovascular system, of heart rates versus an appropriate parameter of a signal produced by a sensor carried by the patient, for the different types of activity requiring different algorithms, in which the parameter value varies in a predetermined way with exercise.

Abstract: An implantable variable rate cardiac pacemaker adaptive to patient exercise has a sensor responsive to each of several preselected different static physical positions of the implant patient to produce electrical output signals uniquely representative of the different physical positions. The pulse generator of the pacemaker is responsive to each output signal of the sensor to generate pacing pulses at a rate different from the rates generated in response to each of the other output signals of the sensor, so that each preselected different physical position has its own representative pacing pulse rate for stimulation of the patient's heart. The generator includes a rate control section adapted to respond to a change by the implant patient from one preselected physical position to another by producing a predetermined pattern of transition from the rate representative of the old position to the rate representative of the new position.

Abstract: A method of making a nerve electrode is performed by forming an electrically insulative resilient array having an elongate backbone member with a plurality of spaced-apart substantially parallel bands, each spanning 360.degree., linked together by the backbone member and skewed from a direction normal to the backbone member; providing non-aligned single openings in the bands to render each of them incomplete with the remaining segments of each band linked by the backbone member and adapted to be spread apart to mount the array over the nerve and, when released, to resiliently close about the nerve; and securing an electrically conductive filament within at least one of the bands.

Abstract: A single chip, semiconductor microcontroller device is adapted to control an aspect of the operation of an external system. The device includes a CPU, program memory for storing instructions to be selectively executed by the CPU to perform the control functions, and peripheral EEPROM data memory adapted to be written to for storing selected data in selected ones of a multiplicity of addresses of the data memory and for selective retrieval of the stored dam by the CPU within its control function. Internal logic in the device is implemented to abort a write operation in progress on the EEPROM data memory upon occurrence of an asynchronous reset of the device. An error flag is set by the logic to indicate that the write operation is being aborted, and the data that was partially written to the EEPROM memory at the time the write operation was aborted is held intact.

Abstract: The usability of an electrically erasable programmable semiconductor memory device is assured after shipment from the factory despite implementing the device with a user option to selectively configure the security, endurance, organization, density or protocol of the memory array of the device. The user selected configuration is made permanent and inaccessible for change by programming associated normally reversible configuration fuses which are rendered incapable of being reprogrammed (reversed) thereafter by the automatic and simultaneous programming of a lockout fuse.

Abstract: An implantable medical interventional device responds to detection of cardiac activity of the patient indicative of ventricular tachycardia (VT) or fibrillation (VF) by successively applying to the patient's heart selected ones of different electrical waveforms for treatment to break the VT or VF, respectively, until the monitored cardiac activity indicates that the treatment has been successful. An accelerometer adapted to sense position and movement of the patient along three mutually orthogonal axes acts as an activity status sensor to detect physical activity and inactivity of the patient to complement the detection of the patient's cardiac activity for confirming that a detected VT is a pathologic tachycardia rather than a physiologic tachycardia, and in response to such confirmation the device selects an appropriate electrical waveform for the treatment.

Abstract: Method and apparatus for treating and controlling sleep disorders by detecting the presence of the sleep disorder under treatment, and, in response, selectively applying a predetermined electrical signal to the patient's vagus nerve for stimulation thereof to alleviate the sleep disorder under treatment. The method and apparatus includes several techniques for detecting the presence of the sleep disorder under treatment, such as sensing the patient's EEG activity in the case of insomniac and hypersomniac patients, or detecting a sudden nodding of the head in the case of narcoleptic patients, or sensing the cessation of respiration in the case of sleep apnea patients.

Abstract: Method and apparatus for treating severe chronic, persistent or recurring neuropathic or psychogenic pain, or pain which is nociceptive if the patient is suffering from terminal disease, by selectively applying a pulse waveform to a lead/electrode implanted on the patient's cervical vagus nerve or other site preferably above the location of the pain to stimulate afferent fibers for activating a descending anti-nociceptive pathway and thereby blocking incoming pain signals. The pulse waveform has programmable pulse width, current level and frequency, and pulse sequence on and off time durations. The programmed pulse sequences are applied to the implanted electrode either on a continuous basis, or only during the period the patient is normally awake, or is initiated by the patient or automatically in response to the onset of pain.

Abstract: A method of forming implantable low dose solid radioactive segments of desired lengths sealed against end leakage of radioactive particles, for use in brachytherapy of malignant tumors. The segments are separated from a single continuous elongate assembly of composite material which includes a continuous solid radioactive elongate core at least partly composed of iridium, sufficiently brittle to break cleanly when cut transverse to its longitudinal axis, encased along substantially its entire longitudinal surface in a sheath having a predetermined thickness and composed of substantially pure platinum or other metal which is malleable relative to the hardness of the core and, when irradiated, has a half-life much shorter than that of the core.

Abstract: Improvements are disclosed in apparatus and techniques for activating an implantable medical device, such as a neurostimulator adapted to treat and control a disorder of a patient where the disorder is susceptible to relief in response to predetermined modulation of the electrical activity of a selected nerve or group of nerves of the patient. The neurostimulator includes a stimulus generator responsive, when activated, to generate a programmable electrical waveform, and an electrode array electrically connected to the stimulus generator for delivering the waveform to a selected nerve of the patient, such as the vagus nerve. The neurostimulator is also adapted to be programmed to provide the waveform with parameter values selected to stimulate the selected nerve to produce the predetermined modulation of the nerve's electrical activity.

Abstract: Method and apparatus for treating and controlling neuropsychiatric disorders including schizophrenia, depression, and borderline personality disorder by selectively applying a predetermined electrical signal to the patient's vagus nerve for stimulation thereof to alleviate the symptoms of the disorder being treated. The electrical signal may be applied continuously, periodically, or intermittently to the vagus nerve depending, in part, on the nature of the disorder being treated. In certain instances, the electrical signal is applied upon detection of an event indicative of onset of the disorder. In other instances, the electrical signal is selectively applied at will to the vagus nerve, such as by patient activation of the signal generator. Parameter values of the electrical signal including pulse width, output current, frequency, on time and off time, are selectively programmable.

Abstract: A semiconductor microcontroller includes the capability to perform analog to digital conversions of an analog signal representative of a variable parameter indicative of the need to exercise a control function. While the analog to digital conversions are being performed, the microcontroller processor can be placed in a sleep mode which eliminates noise arising from switching activities of the processor as a source of inaccuracy in the conversion process. At the end of the conversion, the analog to digital converter can either shut itself down or wake up the processor. Alternatively, the converter may shut itself down in response to a different user selected control signal.

Abstract: A composite source wire for use in treating malignant tumors within a patient's body by localized in vivo radiation with a radioactive source, via a catheter providing a path from a point external to the body to the tumor site. The source wire includes a thin continuous cylindrical flexible elongate stainless steel tube having encased therein a backbone wire running from its proximal end to a point short of its distal end to strengthen and enhance its flexibility, a cylindrical radioactive core adjacent to the distal end in abutting relation to the backbone wire, and a cylindrical plug at the distal end in abutting relation to the other end of the core, with the backbone wire, core and plug being tightly secured within the tube and the tube being securely enclosed about the plug with a tapered tip portion formed at that point.