摘要:
A system includes a memory and a processing module. The memory includes a primary sensing vector and N alternate sensing vectors. The processing module determines a ranking value for each of the N alternate sensing vectors. Each ranking value is indicative of the integrity of a cardiac electrical signal acquired via the corresponding alternate sensing vector. The processing module senses cardiac events using the primary sensing vector, detects a reduction in the integrity of a cardiac electrical signal acquired via the primary sensing vector, and selects one of the N alternate sensing vectors in response to detecting a reduction in the integrity of the cardiac electrical signal acquired via the primary sensing vector. The selection is based on the ranking value associated with the one of the N alternate sensing vectors. The processing module then senses cardiac events using the selected one of the N alternate sensing vectors.
摘要:
A system and method for determining complex intercardiac impedance to detect various cardiac functions are disclosed involving a signal generator means for providing an adjustable direct current signal, a modulator for modulating the adjustable direct current signal to produce a modulated signal, at least one electrode for propagating the modulated signal across a myocardium, at least one sensor for detecting an outputted modulated signal from the myocardium, and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal. The at least one circuit comprises an amplifier, a demodulator, and an integrator. The amplitude and phase of the final outputted modulated signal indicate the complex impedance of the myocardium. Changes in the complex impedance patterns of the myocardium provide indication of reduced oxygen and blood flow to the myocardium. The apparatus can be employed in implantable devices, including cardiac pacemakers and implantable cardioverter defibrillators.
摘要:
A system for monitoring trends in lead impedance includes collecting data from various sources in an implantable medical device system. Lead impedance, non-physiologic sensed events percentage of time in mode switch, results of capture management operation, sensed events, adversion pace counts, refractory sense counts and similar data are used to determine the status of a lead. A set of weighted sum rules are implemented by a software system to process the data and provide displayable information to health care professionals via a programmer. The lead monitoring system includes a patient alert system for patients to seek help in the event a serious lead condition is identified.
摘要:
An implantable medical device is provided for isolating an elongated medical lead from internal device circuitry in the presence of a gradient magnetic or electrical field. The device includes an isolation circuit adapted to operatively connect an internal circuit to the medical lead in a first operative state and to electrically isolate the medical lead from the internal circuit in a second operative state.
摘要:
A system and method for acquiring and processing an EGM signal during a pacing event, wherein a unique converter code is generated upon digitizing of the EGM signal and encrypted in the EGM signal to demarcate a transient event. The system further provides dynamic filtering of the EGM signal and subsequent detection of an intrinsic event signal during the pacing event, from which rhythm events may be diagnosed and classified.
摘要:
An implanted medical device (IMD) conserves power by discriminating received radio frequency (RF) signals between noise and data based on frequency. Data is processed while noise is attenuated. The IMD operates in a first, relatively low, power mode while not receiving the RF signals, in a second, higher, power mode responsive to receiving RF signals, and operates in still higher power mode when the RF signals' average frequency over a selected period is within a predetermined range. A receiver circuit receives RF signals and discriminates a data signal from noise based on average frequency of the RF signals over selected time periods. The receiver circuit operates in a power-conserving mode unless it receives RF signals, or otherwise operates in a relatively higher-power mode. The receiver transfers signals to a telemetry circuit that operates in a power-conserving mode until it receives a valid data signal to operate in higher power mode.
摘要:
An implantable medical device is provided for isolating an elongated medical lead from internal device circuitry in the presence of a gradient magnetic or electrical field. The device includes an isolation circuit adapted to operatively connect an internal circuit to the medical lead in a first operative state and to electrically isolate the medical lead from the internal circuit in a second operative state.
摘要:
A method and an apparatus for performing rate responsive control in an implantable medical device using a scaling factor. Sensor data is acquired using a sensor operatively coupled with the implantable medical device. At least one setpoint for controlling a rate of therapy is generated, the setpoint being based upon the sensor data. A scaling factor adjustment process is performed for scaling the internal sensor data to correlate the sensor data to the setpoint. The rate of therapy is adjusted based upon the scaling factor adjustment.
摘要:
An impedance monitor for discerning edema through evaluation of respiratory rate. Preferred embodiment includes edema monitor and trigger to initiate diagnostic reporting or corrective action when activated. Recording of Long Term Average and Short Term Average values for secondary edema measure based on DC signal level are described as are methods and apparatus for removing unwanted recurring noise.
摘要:
An implantable medical device (IMD) coupled with leads extending to body tissue providing storage of lead related data, monitoring of lead functional status, and indication of lead integrity to the clinician. A lead status monitor (LSM) processes lead related data in a system self test mode and provides a lead status report that identifies and declares conductor/connector issues, insulation issues, and electrode/tissue interface issues indicative of suspected lead related condition mechanisms for each lead employed in the IMD. The LSM operates employing a set of LSM rules that process measured lead impedance values and loss of capture (LOC) values. In a pacing system, particular LSM rules are defined that process periodically determined, pacing pulse characteristic at LOC and bipolar and unipolar lead impedance values that are measured periodically. The lead impedance values are compared to upper and lower limits or trip points of a normal impedance range. Simultaneously, significant changes in lead impedance are detected, and the unipolar impedance value is compared to the bipolar lead impedance value of each lead. Counts of deviations in lead impedances satisfying each LSM rule are maintained. Certain of the lead related condition mechanisms are declared if a count of lead impedance deviations meets a programmed threshold number of such lead impedance deviations within a further programmed number of sequential impedance measurements. Preferably, the pacing pulse strength or voltage at LOC (characterized as LOC_RHEOBASE herein) is periodically determined and compared to a reference LOC_RHEOBASE.