摘要:
Techniques are provided for tracking patient respiration based upon intracardiac electrogram (IEGM) signals or other electrical cardiac signals. Briefly, respiration patterns are detected based upon cycle-to-cycle changes in morphological features associated with individual electrical events with the IEGM signals. For example, slight changes in the peak amplitudes of QRS-complexes, P-waves or T-waves are tracked to identify cyclical variations representative of patient respiration. Alternatively, the integrals of the morphological features of the individual events may be calculated for use in tracking respiration. In any case, once respiration patterns have been identified, episodes of abnormal respiration, such as apnea, hyperpnea, nocturnal asthma, or the like, may be detected and therapy automatically delivered. In particular, techniques for detecting abnormal respiration based on various respiratory parameters derived from the IEGM—such as respiration depth and respiration power—are described.
摘要:
A test assembly for an implantable medical device, which includes a patient simulator capable of providing signals to the implantable medical device that are representative of the patient's organ function to thereby test whether the implantable medical device is capable of detecting circumstances requiring the deliver of therapy. The patient simulator further includes a plurality of loads that can be selected to correspond to the loads actually seen by the implantable medical device when delivering therapy to the patient.
摘要:
An implantable cardiac stimulation system and method provides an external display of a heart activity signal sensed internally by an implantable cardiac stimulation device which has the appearance of a surface EKG. The heart activity signal is sensed by the implanted device and is processed by the device or the external display to have frequency characteristics resembling that of a surface EKG. The heart activity signal to be displayed takes the form of an intracardiac electrogram signal with a low frequency roll-on of no greater than 0.4 Hz and a high frequency cutoff of no less than 20 Hz. This provides a heart activity signal for display which has the appearance and most attributes of a surface EKG.
摘要:
An implantable cardiac stimulation device applies pacing stimulation pulses to a heart and senses evoked responses to the pacing stimulation pulses. A pulse generator applies the stimulation pacing pulses to the heart in accordance with a pacing configuration. A sensor control selects an evoked response sensing electrode configuration from among a plurality of evoked response sensing electrode configurations in response to the pacing configuration. A sensor is then programmed to sense the evoked responses with the selected evoked response sensing electrode configuration. In accordance with a preferred embodiment, signal-to-noise ratios obtained with the various electrode configurations are used to select a best electrode configuration for sensing evoked responses.
摘要:
A system and method are provided for compensating for the drop in blood pressure upon standing. Upon transition from prolonged sitting, lying down, or standing position, the pacemaker abruptly increasing its pacing rate upon postural transition. This pacing rate is triggered when a patient stands after a prolonged reclined or supine/prone position.
摘要:
An implantable cardiac stimulation device comprises a physiologic sensor and one or more pulse generators. The physiologic sensor is capable of sensing a physiologic parameter. The pulse generators can generate cardiac pacing pulses with a timing based on the physiologic parameter. The timed cardiac pacing pulses can prevent a sleep apnea condition. In one example, a cardiac stimulation device has a physiologic sensor and can be configured to pace a patient's heart according to a rest mode of operation. The cardiac stimulation device uses measurements from the physiologic sensor to prevent and treat sleep apnea using a revised rest mode of operation. The revised rest mode operates under a presumption that sleep apnea is primary to a reduced heart rate, rather than secondary, so that pacing at a rate higher than the natural cardiac rate during sleep will prevent sleep apnea.
摘要:
A threshold sensing control for use in an implantable cardiac stimulation device controls the sensing of cardiac activity during a current cardiac cycle of a heart while avoiding sensing a T wave. The system includes a sensing circuit that senses cardiac activity of the heart during a cardiac cycle preceding the current cardiac cycle, a detector that measures selected T wave and R wave characteristics of the cardiac activity and a control circuit that varies the sensing threshold based upon the measured selected R wave and T wave characteristics. The sensing threshold control may be implemented for both intrinsic and paced beats.
摘要:
Time-varying spatial signals are detected by accelerometers mounted within the patient. The signals, representative of the actual 3-D trajectory of the patient, are compared with information representative of expected trajectories retrieved from memory to identify a current patient posture, which may be either a dynamic posture such as walking or running or a change in posture such as rising from a seated position to a standing position. In this manner, a change in posture of the patient is identified based upon a full 3-D trajectory, rather than merely the orientation of the patient at the beginning and the end of the change in posture. In an example described herein, the implantable device stores information representative of expected 3-D trajectories in the form of pre-calculated comparison matrices derived from orthonormal kernels employing Laguerre functions or Lagrange functions. A technique is also described for use by an external programmer for pre-calculating comparison matrices so as to reduce the processing burden within the implanted device during posture detection.
摘要:
An exemplary method includes providing an overdrive pacing rate, based at least in part on the overdrive pacing rate, determining an incidence limit for incidence of intrinsic atrial activity events, determining an incidence of intrinsic atrial activity events, comparing the incidence of intrinsic atrial activity events to the incidence limit and, based at least on the comparing, deciding whether to adjust the overdrive pacing rate. According to this exemplary method, the incidence limit is optionally a function of overdrive pacing rate. Another exemplary method includes determining a dwell limit wherein the dwell limit is optionally a function of overdrive pacing rate. Other exemplary methods, devices, systems, etc., are also disclosed.
摘要:
An exemplary method includes providing an overdrive pacing rate, based at least in part on the overdrive pacing rate, determining an incidence limit for incidence of intrinsic atrial activity events, determining an incidence of intrinsic atrial activity events, comparing the incidence of intrinsic atrial activity events to the incidence limit and, based at least on the comparing, deciding whether to adjust the overdrive pacing rate. According to this exemplary method, the incidence limit is optionally a function of overdrive pacing rate. Another exemplary method includes determining a dwell limit wherein the dwell limit is optionally a function of overdrive pacing rate. Other exemplary methods, devices, systems, etc., are also disclosed.