Abstract: A cardiac pacemaker improves battery longevity by automatically providing optimized threshold amplitude and pulse width values. During capture verification and threshold searching, the pacemaker delivers a pacing pulse and a rapid, maximum amplitude backup pulse in case the pacing pulse fails to capture a patient's heart. Unlike the prior art, the backup pulse is delivered before a predefined Vulnerable Period (during which time pacing might lead to re-entrant tachycardia or fibrillation). This results in threshold searching which is quick, accurate and with smaller rate drops during loss of capture. In another aspect of the present invention, a diagnostic strength-duration curve is approximated by first setting the pulse width to a maximum value and determining the amplitude threshold (rheobase), and then by doubling the amplitude and determining the pulse width threshold (chronaxie).

Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.

Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.

Abstract: In order to terminate pacemaker-mediated tachycardia (PMT), a pacemaker (or "Pacer") capable of atrial synchronized ventricular pacing, defines a retrograde sensing window after a ventricular paced event. If a preset number of sequential retrograde sensed events occur within this window in consecutive pacing cycles the post ventricular atrial refractory period (PVARP) is extended for one pacing cycle (EXT PVARP) and the pacer will not attempt to interrupt a PMT for a relatively long preset interval thereafter.

Abstract: A dual chamber pacemaker is provided, preferably either DDDR or DDIR, having logic hardware and/or software for normally carrying out the DDIR or DDDR mode of operation, and further having means for carrying out a safe atrial pace method of operation in circumstances where normal atrial pacing could otherwise be competitive or result in loss of atrial capture. The pacemaker has means for detecting an atrial sense during PVARP, timing out a delay from the time of the early atrial sense, delivering a safe atrial pulse at the end of the delay, and controlling generation of a ventricular pace pulse in synchronous relation to the safe atrial pulse and with at least a minimum AV interval.

Abstract: A stimulation lead for electrically coupling an implantable pulse generator to an electrode in an apnea treatment system and method of making same. The lead employs a thin substrate of polyurethane or other highly flexible implantable material. Conductors are placed on the substrate by silk screening a conductive ink. The ends of the lead are electrically terminated using rivets which couple through the substrate. The substrate is folded to enclose the conductors, thereby insulating them and protecting them from bodily fluids. Suitable connectors may be attached to either end. The resulting lead is easily fabricated and is extremely thin and flexible.

Abstract: An apparatus for and method of preoperative and intraoperative screening of obstructive sleep apnea patients. The screening device employs a plurality of stimulation channels which may be individually controlled to terminate or prevent an apnea event. The apparatus also contains a plurality of sensor processing channels to permit selection of the optimal sensor configuration and the sensing parameters. The preoperative procedure determines the suitability of a patient for therapy using an automatic implantable system. The type and placement of sensors and stimulation electrodes is also determined. During the intraoperative procedure, the initial screening determinations are verified and the various sensing and stimulation parameters are optimized.

Abstract: An implantable system for the treatment of obstructive sleep apnea by electrical stimulation of the musculature of the upper airway. The system employs one or more sensors to determine the onset of an apnea event. Upon sensing of the onset of an apnea event, the stimulation generator provides a signal for stimulating the muscles of the upper airway at a varying intensity wherein the intensity is gradually increased during the course of the stimulation. The signal is coupled to the muscles to be stimulated by an electrode connected to the stimulation generator by an insulated lead.

Abstract: An improved apparatus for and method of providing feedback to an implantable pulse generator to treat obstructive sleep apnea. Sensors monitor the electrical activity associated with contractions of the diaphragm. The pressure within the thorax and the upper airway are also measured. Whenever electrical activity of the diaphragm suggests that an inspiration cycle is in progress and the pressure sensors show an abnormal pressure differential across the airway, the presence of obstructive sleep apenea is assumed and electrical stimulation is applied to the musculature of the upper airway.

Abstract: An apparatus and method for the control of both central and obstructive sleep apnea using electrical stimulation on a demand basis. Implantable sensors monitor the respiration cycle and determine the occurrence of apnea events. Central apnea is sensed by the passage of an escape interval of time without the sensing of an inspiratory event and a concurrent decrease in blood oxygen saturation. Obstructive sleep apnea is sensed as an abnormal pressure differential across the airway. The diaphragm is electrically stimulated upon sensing of central apnea. The musculature of the upper airway is electrically stimulated upon sensing of an occurrence of obstructive sleep apnea. Stimulation of the upper airway is provided whenever central apnea is sensed.

Abstract: An improved atrial synchronous, dual-chamber pacemaker provided with a variable refractory period during which the pacemaker is not responsive to sensed atrial contractions. The atrial refractory period is selected based upon whether the ventricular pacing pulse preceding the refractory period occurred as a result of time out of the interval corresponding to the basic ventricular pacing rate or due to the time out of the A-V delay interval initiated in response to sensing of a natural atrial contraction.

Abstract: An activity responsive, rate adaptive pacer, which senses and paces in both the atrium and ventricle is disclosed. The pacing rate displayed by the pacer is determined by the sensed activity of the patient, the programmed lower rate, and the patient's atrial or sinus rate.

Abstract: An activity responsive, rate adaptive pacer, which senses and paces in both the atrium and ventricle is disclosed. The pacing rate displayed by the pacer is determined by the sensed activity of the patient, the programmed lower rate, and the patient's atrial or sinus rate.

Abstract: A dual chamber heart pacemaker has atrial and ventricular pulse generators (21, 22) and sense amplifiers (25, 26) which connect respectively to an atrial terminal (11) and a ventricular terminal (12) for connection to the heart. In an atrial synchronous mode, the pacemaker provides ventricular stimulating pulses in response to detected spontaneous atrial contractions, and spaced from them by an A-V interval determined by a timer (31). In an atrial-ventricular sequential mode, a timer (40) causes the pacemaker to deliver sequential atrial and ventricular stimulation pulses which are separated in time by an A-V interval determined by another timer (30). The atrial-ventricular intervals for atrial synchronous mode and atrial-ventricular sequential mode are independent of each other, permitting selection of different A-V intervals for the two modes of operation.

Abstract: An evaluation system for use in conjunction with a body implantable body stimulator, the body stimulator including a stimulation delivering and depolarization sensing lead system. An input connects a digitizer to the lead system, the digitizer digitizing depolarization signals sensed by the lead system. A computing system identifies excursions in the digitized depolarization signals and evaluates identified excursions in accordance with preselected merit criteria. An output gives an indication of at least that excursion having the highest merit that satisfies said merit criteria.

Abstract: An improved atrial synchronous pacemaker and control circuit therefor having a minimum ventricular rate backup mode includes circuitry for preventing occurrence of a closely coupled ventricular pulse which might otherwise occur during the vulnerable repolarization period of the ventricles. A triggering coupling circuit includes a variable or programmable upper rate limit/minimum escape interval timer and switching means therefor for switching to a relatively low maximum rate/minimum escape interval condition while pacing in the ventricular backup mode, and for switching to a higher programmed maximum rate/minimum escape interval limit value while pacing in atrial synchronous mode.

Abstract: An artificial heart pacemaker and control circuit having an atrial synchronous pacing mode includes an output pulse generator for delivering stimulating pulses to the ventricle of the heart, and atrial and ventricular sensing amplifiers for detecting, respectively, atrial and ventricular contractions. The atrial sense amplifier starts an A-V delay timer which provides a delayed triggering pulse to the pulse generator to maintain A-V synchrony. Circuitry is provided for blanking or turning off the atrial sensing amplifier during the time that the ventricular sensing amplifier is refractory, and preferably for a short time interval thereafter, to prevent delivery of an output pulse in response to a premature ventricular contraction erroneously sensed as an atrial contraction.