Medtronic, Inc.

Other

Ray S McDonald

Martin A Rossing

Jerome T Hartlaub

David L Thompson

Lawrence W Shearon

Marc T Stein

Kenneth M Riff

Barouh V Berkovits

Yan S Lee

Lawrence C Hudziak

Michael J German

A method and apparatus for morphologic analysis of an electrical signal, implementable in an implantable device such as a pacemaker, cardioverter, defibrillator or the like. The morphologic analysis uses a phase plane representation of the signal, where the signal and its first derivative are plotted along orthogonal axes. A magnitude signal corresponding to the magnitude component of the trajectory of the phase plane representation is generated and applied to a comparator. The comparator produces an activation signal when the magnitude signal exceeds a predetermined threshold. In response to the activation signal, a quadrant detector selectively applies the magnitude signal to one of four integrators, the selection of one integrator over the others being based at all times upon which quadrant of the phase plane the trajectory is in. When the magnitude decreases below a predetermined threshold, the activation signal is deasserted, whereupon the respective outputs from the four integrators may be interpreted as reflecting of the trajectory of the phase plane representation of the signal. In operation, a particular cardiac event to be detected is induced in a patient, and the resultant phase plane signals are examined to determine particular aspects of the phase plane signals which can be used as an indication that the particular event has occurred. The apparatus is then conditioned to recognize such aspects in subsequent phase plane signals, in order to provide an indication when such aspects are again present in the signals.

Method and apparatus for intracardiac electrogram morphologic analysis

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. The transmitted signals have a frequency equal to the resonance frequency, for causing the resonance circuit to resonate when the medical instrument is not properly placed with the respect to the implantable medical device. A receiver circuit detects the resonance signals generated by the resonant circuit, and an alarm circuit responds to the receiver circuit for generating an appropriate alarm signal.

Apparatus for medical instrument placement verification

The present invention includes an implantable medical device with needle sensing means. The sensing means employs the casing of the device, the body of the patient, and the needle in a circuit which activates electrical means for notifying the physician of needle placement. Contact of the hypodermic needle with the desired location in the reservoir completes a circuit which is activated by power means to provide preferably audible feedback.

Needle placement verifier

An implantable medical device having a main body, and a port in the main body for receiving a medical instrument percutaneously. A resilient dome is mounted in the device for communicating with the medical instrument, and for flexing from a first rest position to a second position after contact with the medical instrument. The dome provides an extra corporeal response signal resulting from the flexion of the dome from the first position to the second position.

Needle placement sensor

A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals. The program signal acceptance circuit performs several different checks on the detected programming signal including a parity check, an access code check and determining if the proper number of signals were transmitted within a given time. The timing circuit of the pulse generator includes a crystal clock oscillator and counter means for counting the clock pulses therefrom to determine the rate of the pacemaker. The pulse width of each pacemaker pulse is determined by using a voltage controlled oscillator in place of the crystal oscillator to obtain energy compensation due to the battery voltage decreasing with time.

Digital cardiac pacemaker with rate limit means

Treatment of re-entry tachycardias through the use of a pacemaker which includes sequentially timed oscillators for delivering stimulating pulses to an atrium and ventricle, preferably on a demand basis, and a circuit for detecting a tachycardia condition and switching to an asynchronous mode of operation. The detector does not respond to a single extraneous or premature beat, but after a predetermined number of beats occurring above a predetermined normal beat rate the detector switches the pacemaker to an asynchronous mode. Relative variation in the phase of the asynchronous pacing and the tachycardia beats results within a short time in occurrence of a pulse in the critical time period to stop the tachycardia. The use of sequential stimulation in both chambers overcomes some of the problems in selecting the proper site for stimulation. Hysteresis is provided in the heartbeat rate detecting circuit for preventing premature discontinuance of the asynchronous mode due to masking of pulses by the refractory period of the QRS-wave amplifying circuits.

Tachycardia treatment

Digital cardiac pacemaker with program acceptance indicator

A body implantable stimulator for providing stimulation signals having selectable energy levels. The stimulator provides a series of one of a predetermined plurality of independent output initiate signals and responds to those signals to provide stimulation signals having an amplitude, duration and repetition rate established by the series of output initiate signals that is provided.

Body stimulator having selectable stimulation energy levels

A pacer having an upper and lower rate limit system for preventing pacer malfunction from producing pacer output pulses above or below preset maximum and minimum rates.

Rate limited pacer

Memory control circuitry for use in a pacemaker or other medical device for setting volatile memory to a known configuration if the battery voltage and/or current drops below the level required for reliable operation of the memory devices.

Memory control circuitry for implantable medical devices

Battery monitor for digital cardiac pacemaker

Digital cardiac pacemaker clocking means

There is disclosed herein a programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, accomplished by threshold safety margin means responsive to a programmed test signal for causing a series of stimulating pulses to be provided a rate different than the previously programmed rate with at least one of the stimulating signals having its energy reduced a predetermined amount. Capture at the reduced energy can be monitored by external equipment.

Growing community of inventors

Saint Paul, MN, United States of America

Ray S McDonald