Abstract: A motion sensor for use within an implantable medical device provides a digital output signal that can be connected directly to the digital processing and control circuits of a pacemaker or other device. This signal may be used to adjust the basic pacing rate of the pacemaker as a function of the physical motion or activity that is sensed. The motion sensor includes an enclosed housing having conductive element therein that partially fills the space of a cavity within the enclosed housing. The conductive element is free to roll, flow or otherwise move around the inside of the housing in response to external forces. The external forces that cause the conductive element to move include the physical motion of the patient as well as the force of gravity. As the conductive element moves within the enclosed housing, it makes electrical contact with at least two of three electrodes that are selectively spaced around the inside periphery of the housing.

Abstract: An implantable pacemaker having a unipolar/bipolar lead interchangeability includes lead impedance measuring capability for automatically measuring lead impedance, initiated by the occurrence of predetermined events, such as whenever a programming change is made, whenever capture fails to occur in response to an applied stimulation pulse, whenever the leads are changed, and whenever a significant change of lead impedance is otherwise detected. If a proper impedance measurement is not sensed for a programmed configuration, additional impedance measurements for other possible configurations are made in an ordered sequence in order to determine if an improper lead has been implanted or if a electrode has broken. If an operable configuration is found, signified by a measurement of impedance as expected, the pacemaker continues operation in that configuration, thereby assuring that capture can continue to occur until such time as the problem which has been detected can be corrected.

Abstract: A non-programmable automatic implantable cardioverter/defibrillator (AICD) capable of providing programmable thresholds for triggering high energy stimulation pulse(s) from the AICD is coupled to an implantable programmable pacemaker which preferably includes bradycardia support and/or tachycardia support using low enery output pulses. When the low energy antitachycardia pulse(s) from the pacemaker fail to terminate a tachycardia, or whenever other various thresholds, as sensed by programmable sensing circuits of the pacemaker, are exceeded, the high enery pulses from the AICD may be selectively invoked by an AICD trigger circuit included within the pacemaker. Coupling between the AICD and pacemaker is by either a direct electrical connection, or by an indirect connection, such as through the use of narrow pulse sequences generated by the pacemaker which are of insufficient energy to invoke a cardiac response but are of sufficient energy to be sensed by the AICD sensing circuits.

Abstract: An automatically adjustable blanking circuit and method of generating an adjustable blanking interval for use with a dual channel implantable pacemaker includes means for generating a basic blanking interval for a first channel of the pacemaker each time a stimulation pulse is generated on a second channel. The basic blanking interval includes a first absolute refractory portion and a second relative refractory portion. During the absolute refractory portion, the sensing circuits of the first channel are disabled. During the relative refractory portion, the sensing circuits of the first channel are enabled and any activity sensed in the first channel is considered to be crosstalk or noise and the basic blanking interval is retriggered. Retriggering of the basic blanking interval continues for so long as activity is sensed in the first channel during the relative refractory portion of each retriggered basic blanking interval, up to a maximum blanking interval.

Abstract: An atrial rate based programmable pacemaker including means for preventing the heart from being paced at an upper rate limit for prolonged periods of time is disclosed which paces the heart at a rate that follows or tracks the atrial rate up to the upper rate limit of the pacemaker, at which point the pacemaker stimulates the heart at the upper rate limit, but also continues to monitor the atrial rate. If the monitored atrial rate exceeds a second upper rate limit, a fast atrial arrhythmia or tachycardia condition is deemed to exist, and the pacemaker automatically switches from its existing mode of operation to an alternate mode of operation in an attempt to break or terminate the fast atrial condition. Alternate embodiments include using an external activity or physiological sensor to control the pacing rate in the new pacing mode, and the inclusion of means for periodically verifying that atrial sensing is occurring, and means for automatically adjusting the sensitivity of the atrial channel as required.

Abstract: In a first embodiment, hysteresis is provided in a rate-responsive pacemaker to allow for natural AV synchrony when possible. In the absence of natural SA node signals, the heart is stimulated at a rate determined by the sensing of physiological need. When a natural heart signal is detected, the hysteresis is activated to extend the escape interval by a predetermined amount which is related to the sensed physiological need. The stimulating pulses are inhibited as long as normal heart activity is sensed. The extension of the escape interval under such conditions eliminates possible competition between normal activity and the paced stimulation. In a second embodiment automatic mode switching is provided in a dual chamber pacemaker to allow for more efficient operation at higher heart rates. When the heart rate (natural or paced) exceeds a prescribed level, such as 90 beats per minute, the pacemaker operates in a single chamber mode, such as VVI.

Abstract: A system for determining P-wave or R-wave capture in response to pacemaker supplied electrical stimuli. One embodiment includes a conventional bipolar atrial lead having a tip electrode, connected to an atrial pulse generator circuit within an implantable pacemaker, and a ring electrode, spaced apart from the tip electrode, connected to a P-wave sensing EGM amplifier within the pacemaker. The bandpass characteristics of the P-wave sensing EGM amplifier allow detection of all electrical frequencies in the atrium within the bandpass chosen. The output signal from this amplifier is selectively telemetered to an external receiver, as is a signal indicating the generation of an atrial stimulation pulse, where the occurrence of atrial stimulation pulses and P-waves can be monitored. In operation, if constant time intervals between the monitored atrial stimulation pulses and P-wave occurrences are present, P-wave capture has occurred.

Abstract: An apparatus for interpreting and displaying cardiac events of a heart connected to an implanted cardiac pacing means (2) is disclosed. The apparatus includes a telemetry head (4), at least one interpreting means (6), and a controller (14). Information telemetered from the implanted pacing means is separated into identifiable sets of data pertaining to prescribed functions, such as atrial events, ventricular events, pacemaker timed events, sensor events, and the like. Skin ECG information may also be received through another interpreting means (12) in addition to pacemaker telemetered data. Parallel processing channels are employed to process all the received data while maintaining synchronization therebetween. Memory means (16) allow the synchronized processed data to be stored for subsequent print out through a D/A converter (20) and printer (22), or to be displayed on a display monitor (26).

Abstract: A rate-responsive pacemaker includes a motion sensor mounted therein. The output signal from the motion sensor is a digital signal that can be connected directly to the digital processing and control circuits of the pacemaker in order to adjust its basic pacing rate as a function of the physical motion or activity that is sensed. The motion sensor includes an enclosed housing having a conductive element therein that partially fills the space of a cavity within the enclosed housing. The conductive element is free to roll, flow, or otherwise move around the inside of the housing in response to external forces. The external forces that cause the conductive element to move include the physical motion of the patient as well as the force of gravity. As the conductive element moves within the enclosed housing, it makes electrical contact with at least two of three electrodes that are selectively spaced around the inside periphery of the housing.

Abstract: A pacemaker and physiological sensor for use therewith that allows the rate at which the pacemaker delivers electrical stimulation pulses to the heart, or the escape interval during which a natural heart event must occur before an electrical stimulation pulse is delivered, to be adjusted as needed in order to satisfy the body's physiological needs. The sensor measures the depolarization time interval between an atrial stimulation pulse, A, and the responsive atrial or ventricle depolarization, P or R respectively, as an indication of the physiological demands placed on the heart. The time interval between a ventricular stimulation pulse, V, and the responsive ventricular depolarization, R, may also be measured and used as an indication of physiological need, and hence as an alternative criteria for rate control. Atrial depolarization is sensed by detecting a P-wave, and ventricular depolarization is preferably sensed by detecting an R-wave.

Abstract: A system for determining P-wave and R-wave capture in response to pacemaker supplied electrical stimuli. One embodiment includes a conventional bipolar atrial lead having a tip electrode, connected to a P-wave pace/sense amplifier and pulse output circuits within an implantable pacemaker, and a ring electrode, spaced apart from the tip electrode, connected to a P-wave sensing EGM amplifier within the pacemaker. The bandpass characteristics of the P-wave pace/sense amplifier allow detection of P-wave frequencies in the absence of atrial stimulation pulses. The bandpass characteristics of the P-wave sensing EGM amplifier allow detection of all electrical frequencies in the atrium within the bandpass chosen. Output signals from these two amplifiers are selectively telemetered to an external receiver, where the occurrence of atrial stimulation pulses and P-waves can be monitored.

Abstract: The present invention is an apparatus (1) for interpreting and displaying cardiac events of a heart connected to a cardiac pacing means (2) comprising a telemetry head (4), a first interpreting mean 6 with means connected to said telemetry head (4), a second interpreting means (12) with means connected to a plurality of ECG electrodes having paddles 8a at their digital end via electrical conduit (10), a control means (14) with means connected to said first and second interpreting means, (6) and (12) respectively, a multi-section memory means (16) with means connected to said control means (14), a D/A convertor (20) with means connected to said memory (16) a printing means (22) with means connected to said D/A convertor (20), logic means (24) with means connected to said memory means (16) and a display means (26) with means connected to said logic means (24).

Abstract: A cardiac stimulation apparatus capable of stimulation in the DDI modality having a first sensing system (46) for sensing electrical activity in the atrium, a second sensing system (48) for sensing electrical activity in the ventricle, a pulse generator logic (24) connected to the first (46) and second (48) sensing systems responsive to electrical activity sensed by the first (46) and second (48) sensing systems for determining the timing for supplying electrical pulses to the atrium and ventricle for their depolarization, a first circuit within the pulse generator logic (24) for preventing synchronization of timing within the pulse generator (24) for producing apparatus generated pulses to the ventricle when electrical activity is sensed in the atrium, a second circuit within the pulse generator logic (24) for inhibiting an apparatus generated pulse to the atrium when electrical activity is sensed resulting from natural depolarization of the atrium, and pulse generator logic timing means (32, 34, 44) for int

Abstract: An apparatus and method for displaying and controlling parameters for a programmable living tissue stimulator system. Visual indicators corresponding to control parameters or signals for the tissue stimulator system are divided into a predetermined number of groups. One of these groups containing a parameter to be selected for the tissue stimulator system is selected, the selected group being identified by a visually identifiable indication. A parameter within that group is then selected for transmission to an implanted memory means which controls an implanted tissue stimulator. In a specific embodiment, a matrix of visual indicators consisting of R rows and S columns is provided, each visual indicator corresponding to a specific control signal. A means is provided whereby at least one visual indicator contained in a selected R row will blink on and off, the blinking indicators identifying control signals to be selected for the implanted memory means.