Abstract: A cardiac rhythm management device includes a dual chamber pacemaker, especially designed for treating congestive heart failure by pacing a plurality of sites. The device incorporates a program microcontroller which is operative to adjust the pacing mode and inter-site delay of the pacemaker so as to achieve optimum hemodynamic performance. Atrial cycle lengths measured during transient (immediate) time intervals following a change in the mode inter-site delay are signal processed and a determination can then be made as to which particular configuration yields the optimum performance. Performance is optimized when the patient is at rest and when the patient exercises so that a rate-adapted dynamic value of the optimum performance can be applied.

Abstract: A device and method for cardiac rhythm management in which a heart chamber is paced in accordance with a pacing mode that employs sense signals from the opposite chamber. A sensing refractory period is provided in order to prevent the pacing interval from being lengthened due to delays in conduction of excitation from the paced chamber to the sensed chamber.

Abstract: A cardiac rhythm management system acquires atrial heart rate variability data. The system provides a graphic or other indication of patient well-being based on the atrial heart rate variability data. Such atrial heart rate variability information provides an indication of the autonomic balance between the sympathetic and parasympathetic/vagal components of the autonomic nervous system. One example of the system also provides time-domain processing of frequency components of the atrial heart rate interval signal to obtain the indication of patient well-being.

Abstract: As a safety feature for a cardiac rhythm management device in which a runaway protection feature may be disabled to allow programmed electrical stimulation and/or burst pacing to evaluate the device's ability to rein in an induced episode of tachycardia, a circuit is provided to automatically re-enable the runaway protection feature not only upon a software fault being detected, but also upon the lapse of a predetermined time interval.

Abstract: A device and method for improving tachyarrhythmia detection when the ventricles are resynchronized by delivering paces to both ventricles separated by a specified offset interval. Timing of escape intervals and tachyarrhythmia detection is based upon senses from one of the ventricles designated as a rate ventricle. A reversion pacing mode is provided in order to prevent tachyarrhythmia detection from being compromised when the rate ventricle is paced after the other ventricle.

Abstract: A device and method for cardiac rhythm management in which a heart chamber is paced in accordance with a pacing mode that employs sense signals from the opposite chamber. A sensing refractory period is provided in order to prevent the pacing interval from being lengthened due to delays in conduction of excitation from the paced chamber to the sensed chamber.

Abstract: A cardiac rhythm management system acquires atrial heart rate variability data. The system provides a graphic or other indication of patient well-being based on the atrial heart rate variability data. Such atrial heart rate variability information provides an indication of the autonomic balance between the sympathetic and parasympathetic/vagal components of the autonomic nervous system. One example of the system also provides time-domain processing of frequency components of the atrial heart rate interval signal to obtain the indication of patient well-being.

Abstract: A hybrid cardiac pacemaker in which the operation of the device is controlled by hardware-based controller as supervised by a microprocessor-based controller. The hardware-based controller comprises a plurality of timers that expire when they reach timer limit values stored in registers updatable by the microprocessor, and a combinational logic array for causing the device to generate pace outputs in accordance with timer expirations and sense signals. The combinational logic array may operate the pacemaker in a number of programmed modes in accordance with a mode value stored in a mode control register by the microprocessor.

Abstract: A hybrid cardiac pacemaker in which the operation of the device is controlled by hardware-based controller as supervised by a microprocessor-based controller. The hardware-based controller comprises a plurality of timers that expire when they reach timer limit values stored in registers updatable by the microprocessor, and a combinational logic array for causing the device to generate pace outputs in accordance with timer expirations and sense signals. The combinational logic array may operate the pacemaker in a number of programmed modes in accordance with a mode value stored in a mode control register by the microprocessor.

Abstract: A cardiac rhythm management system includes techniques for computing an indicated pacing interval, AV delay, or other timing interval. In one embodiment, a variable indicated pacing interval is computed based at least in part on an underlying intrinsic heart rate. The indicated pacing interval is used to time the delivery of biventricular coordination therapy even when ventricular heart rates are irregular, such as in the presence of atrial fibrillation. In another embodiment, a variable filter indicated AV interval is computed based at least in part on an underlying intrinsic AV interval. The indicated AV interval is used to time the delivery of atrial tracking biventricular coordination therapy when atrial heart rhythms are not arrhythmic. Other indicated timing intervals may be similarly determined. The indicated pacing interval, AV delay, or other timing interval can also be used in combination with a sensor indicated rate indicator.

Abstract: A hybrid cardiac pacemaker in which the operation of the device is controlled by hardware-based controller as supervised by a microprocessor-based controller. The hardware-based controller comprises a plurality of timers that expire when they reach timer limit values stored in registers updatable by the microprocessor, and a combinational logic array for causing the device to generate pace outputs in accordance with timer expirations and sense signals. The combinational logic array may operate the pacemaker in a number of programmed modes in accordance with a mode value stored in a mode control register by the microprocessor.

Abstract: A cardiac rhythm management device includes a dual chamber pacemaker, especially designed for treating congestive heart failure by pacing a plurality of sites. The device incorporates a program microcontroller which is operative to adjust the pacing mode and inter-site delay of the pacemaker so as to achieve optimum hemodynamic performance. Atrial cycle lengths measured during transient (immediate) time intervals following a change in the mode inter-site delay are signal processed and a determination can then be made as to which particular configuration yields the optimum performance. Performance is optimized when the patient is at rest and when the patient exercises so that a rate-adapted dynamic value of the optimum performance can be applied.

Abstract: A cardiac rhythm management system includes techniques for computing an indicated pacing interval, AV delay, or other timing interval. In one embodiment, a variable indicated pacing interval is computed based at least in part on an underlying intrinsic heart rate. The indicated pacing interval is used to time the delivery of biventricular coordination therapy even when ventricular heart rates are irregular, such as in the presence of atrial fibrillation. In another embodiment, a variable filter indicated AV interval is computed based at least in part on an underlying intrinsic AV interval. The indicated AV interval is used to time the delivery of atrial tracking biventricular coordination therapy when atrial heart rhythms are not arrhythmic. Other indicated timing intervals may be similarly determined. The indicated pacing interval, AV delay, or other timing interval can also be used in combination with a sensor indicated rate indicator.

Abstract: A cardiac rhythm management system includes techniques for computing an indicated pacing interval, AV delay, or other timing interval. In one embodiment, a variable indicated pacing interval is computed based at least in part on an underlying intrinsic heart rate. The indicated pacing interval is used to time the delivery of biventricular coordination therapy even when ventricular heart rates are irregular, such as in the presence of atrial fibrillation. In another embodiment, a variable filter indicated AV interval is computed based at least in part on an underlying intrinsic AV interval. The indicated AV interval is used to time the delivery of atrial tracking biventricular coordination therapy when atrial heart rhythms are not arrhythmic. Other indicated timing intervals may be similarly determined. The indicated pacing interval, AV delay, or other timing interval can also be used in combination with a sensor indicated rate indicator.

Abstract: An apparatus and method of manufacturing a laser print head include the steps of mounting a laser array (70) on a print head block (80), measuring misalignment of the laser array (70) to determine a correction factor, mounting a cylinder lens (20) on a cylinder lens holder (25), inducing a predetermined bend into the cylinder lens (20) corresponding to the correction factor by allowing the cylinder lens (20) to sag on upright posts (26) of the cylinder lens holder (25), attaching the cylinder lens (20) to a sub-mount (30), attaching flexures (50) to the sub-mount (30), aligning the cylinder lens (20) to the laser array (70), and attaching the flexures (50) to the print head block (80). The bend in the cylinder lens corrects for misalignment in the laser array (70) so that the array of spots at the image plane is in an approximately straight line. In one embodiment, the sub-mount and cylinder lens have approximately the same thermal coefficient of expansion.

Abstract: A laser print head structure includes a laser diode array (14) coupled to a heat sink (10). A cylindrical lens element (20) is aligned with the laser diode array and bonded to the heat sink. A binary optical element (22) is then aligned with the cylindrical lens element and attached to the heat sink through the use of flexures (24). The use of the flexures permits the binary optical element to "float" in the plane of the laser diode array, thereby maintaining alignment even when the thermal expansion characteristics of the binary optical element are different from the thermal expansion characteristics of the heat sink. Anti-wicking slots (18) are provided in the heat sink at locations between the bonding points of the cylindrical lens element and the laser diode array. The anti-wicking slots, through capillary action, prevent excess adhesive from wicking along the cylindrical lens element and onto the facets of the lasers in the laser diode array.

Abstract: A method of making a heat shield for an exhaust system tailpipe which comprises the steps of positioning a blank of sheet metal between a die having a forming surface of generally arcuately concave cross-sectional configuration which extends in a generally arcuately convex direction and a straight cylindrical body of elastomeric material having a longitudinal axis extending generally tangentially with respect to the arcuately convex direction of extent of the die forming surface, effecting an initial relative movement between the die and the cylindrical elastomeric body in a direction toward one another so as to compress a central portion of the sheet metal blank to a central portion of the die forming surface by a central portion of the exterior surface of the cylindrical elastomeric body while the latter is in a straight condition, and progressively flexing opposite end portions of the cylindrical elastomeric body in directions toward the end portions of the die forming surface so as to progressively compre

Abstract: A method is disclosed for optimizing the bandwidth of a radio receiver cale of receiving widely varying input data rates. The method may be utilized with known superheterodyne receivers having certain modifications to allow for the ability to vary the intermediate frequency and the center frequency of the associated bandpass filters over a continuous range of values. The method includes the steps of determining the optimum intermediate frequency bandwidth for a given input data rate, adjusting a tunable bandwidth filter to a center frequency which is a predetermined multiple of the desired intermediate frequency bandwidth, and producing an intermediate frequency equal to the tuned frequency of the filter.

Abstract: The data stream input to the recovery logic is taken from a point at which its transitions are timecoincident with those of the data stream input to the phase comparator of the phase locked oscillator loop used to control the generation of the recovery windows. No delay is provided between the data stream take-off point and its input to the recovery logic. The PLO and the window generating circuits cooperate to maintain data and clock representative transitions in the data stream applied to the recovery logic centered in the respective windows.